TOMOYO Linux Cross Reference
Linux/kernel/events/core.c

   // SPDX-License-Identifier: GPL-2.0
   /*
    * Performance events core code:
    *
    *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
    *  Copyright (C) 2008-2011 Red Hat, Inc., Ingo Molnar
    *  Copyright (C) 2008-2011 Red Hat, Inc., Peter Zijlstra
    *  Copyright  ©  2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
    */
  
  #include <linux/fs.h>
  #include <linux/mm.h>
  #include <linux/cpu.h>
  #include <linux/smp.h>
  #include <linux/idr.h>
  #include <linux/file.h>
  #include <linux/poll.h>
  #include <linux/slab.h>
  #include <linux/hash.h>
  #include <linux/tick.h>
  #include <linux/sysfs.h>
  #include <linux/dcache.h>
  #include <linux/percpu.h>
  #include <linux/ptrace.h>
  #include <linux/reboot.h>
  #include <linux/vmstat.h>
  #include <linux/device.h>
  #include <linux/export.h>
  #include <linux/vmalloc.h>
  #include <linux/hardirq.h>
  #include <linux/hugetlb.h>
  #include <linux/rculist.h>
  #include <linux/uaccess.h>
  #include <linux/syscalls.h>
  #include <linux/anon_inodes.h>
  #include <linux/kernel_stat.h>
  #include <linux/cgroup.h>
  #include <linux/perf_event.h>
  #include <linux/trace_events.h>
  #include <linux/hw_breakpoint.h>
  #include <linux/mm_types.h>
  #include <linux/module.h>
  #include <linux/mman.h>
  #include <linux/compat.h>
  #include <linux/bpf.h>
  #include <linux/filter.h>
  #include <linux/namei.h>
  #include <linux/parser.h>
  #include <linux/sched/clock.h>
  #include <linux/sched/mm.h>
  #include <linux/proc_ns.h>
  #include <linux/mount.h>
  #include <linux/min_heap.h>
  #include <linux/highmem.h>
  #include <linux/pgtable.h>
  #include <linux/buildid.h>
  #include <linux/task_work.h>
  
  #include "internal.h"
  
  #include <asm/irq_regs.h>
  
  typedef int (*remote_function_f)(void *);
  
  struct remote_function_call {
          struct task_struct      *p;
          remote_function_f       func;
          void                    *info;
          int                     ret;
  };
  
  static void remote_function(void *data)
  {
          struct remote_function_call *tfc = data;
          struct task_struct *p = tfc->p;
  
          if (p) {
                  /* -EAGAIN */
                  if (task_cpu(p) != smp_processor_id())
                          return;
  
                  /*
                   * Now that we're on right CPU with IRQs disabled, we can test
                   * if we hit the right task without races.
                   */
  
                  tfc->ret = -ESRCH; /* No such (running) process */
                  if (p != current)
                          return;
          }
  
          tfc->ret = tfc->func(tfc->info);
  }
  
  /**
   * task_function_call - call a function on the cpu on which a task runs
   * @p:          the task to evaluate
   * @func:       the function to be called
   * @info:       the function call argument
  *
  * Calls the function @func when the task is currently running. This might
  * be on the current CPU, which just calls the function directly.  This will
  * retry due to any failures in smp_call_function_single(), such as if the
  * task_cpu() goes offline concurrently.
  *
  * returns @func return value or -ESRCH or -ENXIO when the process isn't running
  */
 static int
 task_function_call(struct task_struct *p, remote_function_f func, void *info)
 {
         struct remote_function_call data = {
                 .p      = p,
                 .func   = func,
                 .info   = info,
                 .ret    = -EAGAIN,
         };
         int ret;
 
         for (;;) {
                 ret = smp_call_function_single(task_cpu(p), remote_function,
                                                &data, 1);
                 if (!ret)
                         ret = data.ret;
 
                 if (ret != -EAGAIN)
                         break;
 
                 cond_resched();
         }
 
         return ret;
 }
 
 /**
  * cpu_function_call - call a function on the cpu
  * @cpu:        target cpu to queue this function
  * @func:       the function to be called
  * @info:       the function call argument
  *
  * Calls the function @func on the remote cpu.
  *
  * returns: @func return value or -ENXIO when the cpu is offline
  */
 static int cpu_function_call(int cpu, remote_function_f func, void *info)
 {
         struct remote_function_call data = {
                 .p      = NULL,
                 .func   = func,
                 .info   = info,
                 .ret    = -ENXIO, /* No such CPU */
         };
 
         smp_call_function_single(cpu, remote_function, &data, 1);
 
         return data.ret;
 }
 
 static void perf_ctx_lock(struct perf_cpu_context *cpuctx,
                           struct perf_event_context *ctx)
 {
         raw_spin_lock(&cpuctx->ctx.lock);
         if (ctx)
                 raw_spin_lock(&ctx->lock);
 }
 
 static void perf_ctx_unlock(struct perf_cpu_context *cpuctx,
                             struct perf_event_context *ctx)
 {
         if (ctx)
                 raw_spin_unlock(&ctx->lock);
         raw_spin_unlock(&cpuctx->ctx.lock);
 }
 
 #define TASK_TOMBSTONE ((void *)-1L)
 
 static bool is_kernel_event(struct perf_event *event)
 {
         return READ_ONCE(event->owner) == TASK_TOMBSTONE;
 }
 
 static DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);
 
 struct perf_event_context *perf_cpu_task_ctx(void)
 {
         lockdep_assert_irqs_disabled();
         return this_cpu_ptr(&perf_cpu_context)->task_ctx;
 }
 
 /*
  * On task ctx scheduling...
  *
  * When !ctx->nr_events a task context will not be scheduled. This means
  * we can disable the scheduler hooks (for performance) without leaving
  * pending task ctx state.
  *
  * This however results in two special cases:
  *
  *  - removing the last event from a task ctx; this is relatively straight
  *    forward and is done in __perf_remove_from_context.
  *
  *  - adding the first event to a task ctx; this is tricky because we cannot
  *    rely on ctx->is_active and therefore cannot use event_function_call().
  *    See perf_install_in_context().
  *
  * If ctx->nr_events, then ctx->is_active and cpuctx->task_ctx are set.
  */
 
 typedef void (*event_f)(struct perf_event *, struct perf_cpu_context *,
                         struct perf_event_context *, void *);
 
 struct event_function_struct {
         struct perf_event *event;
         event_f func;
         void *data;
 };
 
 static int event_function(void *info)
 {
         struct event_function_struct *efs = info;
         struct perf_event *event = efs->event;
         struct perf_event_context *ctx = event->ctx;
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_context *task_ctx = cpuctx->task_ctx;
         int ret = 0;
 
         lockdep_assert_irqs_disabled();
 
         perf_ctx_lock(cpuctx, task_ctx);
         /*
          * Since we do the IPI call without holding ctx->lock things can have
          * changed, double check we hit the task we set out to hit.
          */
         if (ctx->task) {
                 if (ctx->task != current) {
                         ret = -ESRCH;
                         goto unlock;
                 }
 
                 /*
                  * We only use event_function_call() on established contexts,
                  * and event_function() is only ever called when active (or
                  * rather, we'll have bailed in task_function_call() or the
                  * above ctx->task != current test), therefore we must have
                  * ctx->is_active here.
                  */
                 WARN_ON_ONCE(!ctx->is_active);
                 /*
                  * And since we have ctx->is_active, cpuctx->task_ctx must
                  * match.
                  */
                 WARN_ON_ONCE(task_ctx != ctx);
         } else {
                 WARN_ON_ONCE(&cpuctx->ctx != ctx);
         }
 
         efs->func(event, cpuctx, ctx, efs->data);
 unlock:
         perf_ctx_unlock(cpuctx, task_ctx);
 
         return ret;
 }
 
 static void event_function_call(struct perf_event *event, event_f func, void *data)
 {
         struct perf_event_context *ctx = event->ctx;
         struct task_struct *task = READ_ONCE(ctx->task); /* verified in event_function */
         struct perf_cpu_context *cpuctx;
         struct event_function_struct efs = {
                 .event = event,
                 .func = func,
                 .data = data,
         };
 
         if (!event->parent) {
                 /*
                  * If this is a !child event, we must hold ctx::mutex to
                  * stabilize the event->ctx relation. See
                  * perf_event_ctx_lock().
                  */
                 lockdep_assert_held(&ctx->mutex);
         }
 
         if (!task) {
                 cpu_function_call(event->cpu, event_function, &efs);
                 return;
         }
 
         if (task == TASK_TOMBSTONE)
                 return;
 
 again:
         if (!task_function_call(task, event_function, &efs))
                 return;
 
         local_irq_disable();
         cpuctx = this_cpu_ptr(&perf_cpu_context);
         perf_ctx_lock(cpuctx, ctx);
         /*
          * Reload the task pointer, it might have been changed by
          * a concurrent perf_event_context_sched_out().
          */
         task = ctx->task;
         if (task == TASK_TOMBSTONE)
                 goto unlock;
         if (ctx->is_active) {
                 perf_ctx_unlock(cpuctx, ctx);
                 local_irq_enable();
                 goto again;
         }
         func(event, NULL, ctx, data);
 unlock:
         perf_ctx_unlock(cpuctx, ctx);
         local_irq_enable();
 }
 
 /*
  * Similar to event_function_call() + event_function(), but hard assumes IRQs
  * are already disabled and we're on the right CPU.
  */
 static void event_function_local(struct perf_event *event, event_f func, void *data)
 {
         struct perf_event_context *ctx = event->ctx;
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct task_struct *task = READ_ONCE(ctx->task);
         struct perf_event_context *task_ctx = NULL;
 
         lockdep_assert_irqs_disabled();
 
         if (task) {
                 if (task == TASK_TOMBSTONE)
                         return;
 
                 task_ctx = ctx;
         }
 
         perf_ctx_lock(cpuctx, task_ctx);
 
         task = ctx->task;
         if (task == TASK_TOMBSTONE)
                 goto unlock;
 
         if (task) {
                 /*
                  * We must be either inactive or active and the right task,
                  * otherwise we're screwed, since we cannot IPI to somewhere
                  * else.
                  */
                 if (ctx->is_active) {
                         if (WARN_ON_ONCE(task != current))
                                 goto unlock;
 
                         if (WARN_ON_ONCE(cpuctx->task_ctx != ctx))
                                 goto unlock;
                 }
         } else {
                 WARN_ON_ONCE(&cpuctx->ctx != ctx);
         }
 
         func(event, cpuctx, ctx, data);
 unlock:
         perf_ctx_unlock(cpuctx, task_ctx);
 }
 
 #define PERF_FLAG_ALL (PERF_FLAG_FD_NO_GROUP |\
                        PERF_FLAG_FD_OUTPUT  |\
                        PERF_FLAG_PID_CGROUP |\
                        PERF_FLAG_FD_CLOEXEC)
 
 /*
  * branch priv levels that need permission checks
  */
 #define PERF_SAMPLE_BRANCH_PERM_PLM \
         (PERF_SAMPLE_BRANCH_KERNEL |\
          PERF_SAMPLE_BRANCH_HV)
 
 enum event_type_t {
         EVENT_FLEXIBLE = 0x1,
         EVENT_PINNED = 0x2,
         EVENT_TIME = 0x4,
         /* see ctx_resched() for details */
         EVENT_CPU = 0x8,
         EVENT_CGROUP = 0x10,
         EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
 };
 
 /*
  * perf_sched_events : >0 events exist
  */
 
 static void perf_sched_delayed(struct work_struct *work);
 DEFINE_STATIC_KEY_FALSE(perf_sched_events);
 static DECLARE_DELAYED_WORK(perf_sched_work, perf_sched_delayed);
 static DEFINE_MUTEX(perf_sched_mutex);
 static atomic_t perf_sched_count;
 
 static DEFINE_PER_CPU(struct pmu_event_list, pmu_sb_events);
 
 static atomic_t nr_mmap_events __read_mostly;
 static atomic_t nr_comm_events __read_mostly;
 static atomic_t nr_namespaces_events __read_mostly;
 static atomic_t nr_task_events __read_mostly;
 static atomic_t nr_freq_events __read_mostly;
 static atomic_t nr_switch_events __read_mostly;
 static atomic_t nr_ksymbol_events __read_mostly;
 static atomic_t nr_bpf_events __read_mostly;
 static atomic_t nr_cgroup_events __read_mostly;
 static atomic_t nr_text_poke_events __read_mostly;
 static atomic_t nr_build_id_events __read_mostly;
 
 static LIST_HEAD(pmus);
 static DEFINE_MUTEX(pmus_lock);
 static struct srcu_struct pmus_srcu;
 static cpumask_var_t perf_online_mask;
 static struct kmem_cache *perf_event_cache;
 
 /*
  * perf event paranoia level:
  *  -1 - not paranoid at all
  *   0 - disallow raw tracepoint access for unpriv
  *   1 - disallow cpu events for unpriv
  *   2 - disallow kernel profiling for unpriv
  */
 int sysctl_perf_event_paranoid __read_mostly = 2;
 
 /* Minimum for 512 kiB + 1 user control page */
 int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
 
 /*
  * max perf event sample rate
  */
 #define DEFAULT_MAX_SAMPLE_RATE         100000
 #define DEFAULT_SAMPLE_PERIOD_NS        (NSEC_PER_SEC / DEFAULT_MAX_SAMPLE_RATE)
 #define DEFAULT_CPU_TIME_MAX_PERCENT    25
 
 int sysctl_perf_event_sample_rate __read_mostly = DEFAULT_MAX_SAMPLE_RATE;
 
 static int max_samples_per_tick __read_mostly   = DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ);
 static int perf_sample_period_ns __read_mostly  = DEFAULT_SAMPLE_PERIOD_NS;
 
 static int perf_sample_allowed_ns __read_mostly =
         DEFAULT_SAMPLE_PERIOD_NS * DEFAULT_CPU_TIME_MAX_PERCENT / 100;
 
 static void update_perf_cpu_limits(void)
 {
         u64 tmp = perf_sample_period_ns;
 
         tmp *= sysctl_perf_cpu_time_max_percent;
         tmp = div_u64(tmp, 100);
         if (!tmp)
                 tmp = 1;
 
         WRITE_ONCE(perf_sample_allowed_ns, tmp);
 }
 
 static bool perf_rotate_context(struct perf_cpu_pmu_context *cpc);
 
 int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write,
                                        void *buffer, size_t *lenp, loff_t *ppos)
 {
         int ret;
         int perf_cpu = sysctl_perf_cpu_time_max_percent;
         /*
          * If throttling is disabled don't allow the write:
          */
         if (write && (perf_cpu == 100 || perf_cpu == 0))
                 return -EINVAL;
 
         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
         if (ret || !write)
                 return ret;
 
         max_samples_per_tick = DIV_ROUND_UP(sysctl_perf_event_sample_rate, HZ);
         perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
         update_perf_cpu_limits();
 
         return 0;
 }
 
 int sysctl_perf_cpu_time_max_percent __read_mostly = DEFAULT_CPU_TIME_MAX_PERCENT;
 
 int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write,
                 void *buffer, size_t *lenp, loff_t *ppos)
 {
         int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 
         if (ret || !write)
                 return ret;
 
         if (sysctl_perf_cpu_time_max_percent == 100 ||
             sysctl_perf_cpu_time_max_percent == 0) {
                 printk(KERN_WARNING
                        "perf: Dynamic interrupt throttling disabled, can hang your system!\n");
                 WRITE_ONCE(perf_sample_allowed_ns, 0);
         } else {
                 update_perf_cpu_limits();
         }
 
         return 0;
 }
 
 /*
  * perf samples are done in some very critical code paths (NMIs).
  * If they take too much CPU time, the system can lock up and not
  * get any real work done.  This will drop the sample rate when
  * we detect that events are taking too long.
  */
 #define NR_ACCUMULATED_SAMPLES 128
 static DEFINE_PER_CPU(u64, running_sample_length);
 
 static u64 __report_avg;
 static u64 __report_allowed;
 
 static void perf_duration_warn(struct irq_work *w)
 {
         printk_ratelimited(KERN_INFO
                 "perf: interrupt took too long (%lld > %lld), lowering "
                 "kernel.perf_event_max_sample_rate to %d\n",
                 __report_avg, __report_allowed,
                 sysctl_perf_event_sample_rate);
 }
 
 static DEFINE_IRQ_WORK(perf_duration_work, perf_duration_warn);
 
 void perf_sample_event_took(u64 sample_len_ns)
 {
         u64 max_len = READ_ONCE(perf_sample_allowed_ns);
         u64 running_len;
         u64 avg_len;
         u32 max;
 
         if (max_len == 0)
                 return;
 
         /* Decay the counter by 1 average sample. */
         running_len = __this_cpu_read(running_sample_length);
         running_len -= running_len/NR_ACCUMULATED_SAMPLES;
         running_len += sample_len_ns;
         __this_cpu_write(running_sample_length, running_len);
 
         /*
          * Note: this will be biased artificially low until we have
          * seen NR_ACCUMULATED_SAMPLES. Doing it this way keeps us
          * from having to maintain a count.
          */
         avg_len = running_len/NR_ACCUMULATED_SAMPLES;
         if (avg_len <= max_len)
                 return;
 
         __report_avg = avg_len;
         __report_allowed = max_len;
 
         /*
          * Compute a throttle threshold 25% below the current duration.
          */
         avg_len += avg_len / 4;
         max = (TICK_NSEC / 100) * sysctl_perf_cpu_time_max_percent;
         if (avg_len < max)
                 max /= (u32)avg_len;
         else
                 max = 1;
 
         WRITE_ONCE(perf_sample_allowed_ns, avg_len);
         WRITE_ONCE(max_samples_per_tick, max);
 
         sysctl_perf_event_sample_rate = max * HZ;
         perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
 
         if (!irq_work_queue(&perf_duration_work)) {
                 early_printk("perf: interrupt took too long (%lld > %lld), lowering "
                              "kernel.perf_event_max_sample_rate to %d\n",
                              __report_avg, __report_allowed,
                              sysctl_perf_event_sample_rate);
         }
 }
 
 static atomic64_t perf_event_id;
 
 static void update_context_time(struct perf_event_context *ctx);
 static u64 perf_event_time(struct perf_event *event);
 
 void __weak perf_event_print_debug(void)        { }
 
 static inline u64 perf_clock(void)
 {
         return local_clock();
 }
 
 static inline u64 perf_event_clock(struct perf_event *event)
 {
         return event->clock();
 }
 
 /*
  * State based event timekeeping...
  *
  * The basic idea is to use event->state to determine which (if any) time
  * fields to increment with the current delta. This means we only need to
  * update timestamps when we change state or when they are explicitly requested
  * (read).
  *
  * Event groups make things a little more complicated, but not terribly so. The
  * rules for a group are that if the group leader is OFF the entire group is
  * OFF, irrespective of what the group member states are. This results in
  * __perf_effective_state().
  *
  * A further ramification is that when a group leader flips between OFF and
  * !OFF, we need to update all group member times.
  *
  *
  * NOTE: perf_event_time() is based on the (cgroup) context time, and thus we
  * need to make sure the relevant context time is updated before we try and
  * update our timestamps.
  */
 
 static __always_inline enum perf_event_state
 __perf_effective_state(struct perf_event *event)
 {
         struct perf_event *leader = event->group_leader;
 
         if (leader->state <= PERF_EVENT_STATE_OFF)
                 return leader->state;
 
         return event->state;
 }
 
 static __always_inline void
 __perf_update_times(struct perf_event *event, u64 now, u64 *enabled, u64 *running)
 {
         enum perf_event_state state = __perf_effective_state(event);
         u64 delta = now - event->tstamp;
 
         *enabled = event->total_time_enabled;
         if (state >= PERF_EVENT_STATE_INACTIVE)
                 *enabled += delta;
 
         *running = event->total_time_running;
         if (state >= PERF_EVENT_STATE_ACTIVE)
                 *running += delta;
 }
 
 static void perf_event_update_time(struct perf_event *event)
 {
         u64 now = perf_event_time(event);
 
         __perf_update_times(event, now, &event->total_time_enabled,
                                         &event->total_time_running);
         event->tstamp = now;
 }
 
 static void perf_event_update_sibling_time(struct perf_event *leader)
 {
         struct perf_event *sibling;
 
         for_each_sibling_event(sibling, leader)
                 perf_event_update_time(sibling);
 }
 
 static void
 perf_event_set_state(struct perf_event *event, enum perf_event_state state)
 {
         if (event->state == state)
                 return;
 
         perf_event_update_time(event);
         /*
          * If a group leader gets enabled/disabled all its siblings
          * are affected too.
          */
         if ((event->state < 0) ^ (state < 0))
                 perf_event_update_sibling_time(event);
 
         WRITE_ONCE(event->state, state);
 }
 
 /*
  * UP store-release, load-acquire
  */
 
 #define __store_release(ptr, val)                                       \
 do {                                                                    \
         barrier();                                                      \
         WRITE_ONCE(*(ptr), (val));                                      \
 } while (0)
 
 #define __load_acquire(ptr)                                             \
 ({                                                                      \
         __unqual_scalar_typeof(*(ptr)) ___p = READ_ONCE(*(ptr));        \
         barrier();                                                      \
         ___p;                                                           \
 })
 
 static void perf_ctx_disable(struct perf_event_context *ctx, bool cgroup)
 {
         struct perf_event_pmu_context *pmu_ctx;
 
         list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
                 if (cgroup && !pmu_ctx->nr_cgroups)
                         continue;
                 perf_pmu_disable(pmu_ctx->pmu);
         }
 }
 
 static void perf_ctx_enable(struct perf_event_context *ctx, bool cgroup)
 {
         struct perf_event_pmu_context *pmu_ctx;
 
         list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
                 if (cgroup && !pmu_ctx->nr_cgroups)
                         continue;
                 perf_pmu_enable(pmu_ctx->pmu);
         }
 }
 
 static void ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type);
 static void ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type);
 
 #ifdef CONFIG_CGROUP_PERF
 
 static inline bool
 perf_cgroup_match(struct perf_event *event)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
 
         /* @event doesn't care about cgroup */
         if (!event->cgrp)
                 return true;
 
         /* wants specific cgroup scope but @cpuctx isn't associated with any */
         if (!cpuctx->cgrp)
                 return false;
 
         /*
          * Cgroup scoping is recursive.  An event enabled for a cgroup is
          * also enabled for all its descendant cgroups.  If @cpuctx's
          * cgroup is a descendant of @event's (the test covers identity
          * case), it's a match.
          */
         return cgroup_is_descendant(cpuctx->cgrp->css.cgroup,
                                     event->cgrp->css.cgroup);
 }
 
 static inline void perf_detach_cgroup(struct perf_event *event)
 {
         css_put(&event->cgrp->css);
         event->cgrp = NULL;
 }
 
 static inline int is_cgroup_event(struct perf_event *event)
 {
         return event->cgrp != NULL;
 }
 
 static inline u64 perf_cgroup_event_time(struct perf_event *event)
 {
         struct perf_cgroup_info *t;
 
         t = per_cpu_ptr(event->cgrp->info, event->cpu);
         return t->time;
 }
 
 static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
 {
         struct perf_cgroup_info *t;
 
         t = per_cpu_ptr(event->cgrp->info, event->cpu);
         if (!__load_acquire(&t->active))
                 return t->time;
         now += READ_ONCE(t->timeoffset);
         return now;
 }
 
 static inline void __update_cgrp_time(struct perf_cgroup_info *info, u64 now, bool adv)
 {
         if (adv)
                 info->time += now - info->timestamp;
         info->timestamp = now;
         /*
          * see update_context_time()
          */
         WRITE_ONCE(info->timeoffset, info->time - info->timestamp);
 }
 
 static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx, bool final)
 {
         struct perf_cgroup *cgrp = cpuctx->cgrp;
         struct cgroup_subsys_state *css;
         struct perf_cgroup_info *info;
 
         if (cgrp) {
                 u64 now = perf_clock();
 
                 for (css = &cgrp->css; css; css = css->parent) {
                         cgrp = container_of(css, struct perf_cgroup, css);
                         info = this_cpu_ptr(cgrp->info);
 
                         __update_cgrp_time(info, now, true);
                         if (final)
                                 __store_release(&info->active, 0);
                 }
         }
 }
 
 static inline void update_cgrp_time_from_event(struct perf_event *event)
 {
         struct perf_cgroup_info *info;
 
         /*
          * ensure we access cgroup data only when needed and
          * when we know the cgroup is pinned (css_get)
          */
         if (!is_cgroup_event(event))
                 return;
 
         info = this_cpu_ptr(event->cgrp->info);
         /*
          * Do not update time when cgroup is not active
          */
         if (info->active)
                 __update_cgrp_time(info, perf_clock(), true);
 }
 
 static inline void
 perf_cgroup_set_timestamp(struct perf_cpu_context *cpuctx)
 {
         struct perf_event_context *ctx = &cpuctx->ctx;
         struct perf_cgroup *cgrp = cpuctx->cgrp;
         struct perf_cgroup_info *info;
         struct cgroup_subsys_state *css;
 
         /*
          * ctx->lock held by caller
          * ensure we do not access cgroup data
          * unless we have the cgroup pinned (css_get)
          */
         if (!cgrp)
                 return;
 
         WARN_ON_ONCE(!ctx->nr_cgroups);
 
         for (css = &cgrp->css; css; css = css->parent) {
                 cgrp = container_of(css, struct perf_cgroup, css);
                 info = this_cpu_ptr(cgrp->info);
                 __update_cgrp_time(info, ctx->timestamp, false);
                 __store_release(&info->active, 1);
         }
 }
 
 /*
  * reschedule events based on the cgroup constraint of task.
  */
 static void perf_cgroup_switch(struct task_struct *task)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_cgroup *cgrp;
 
         /*
          * cpuctx->cgrp is set when the first cgroup event enabled,
          * and is cleared when the last cgroup event disabled.
          */
         if (READ_ONCE(cpuctx->cgrp) == NULL)
                 return;
 
         WARN_ON_ONCE(cpuctx->ctx.nr_cgroups == 0);
 
         cgrp = perf_cgroup_from_task(task, NULL);
         if (READ_ONCE(cpuctx->cgrp) == cgrp)
                 return;
 
         perf_ctx_lock(cpuctx, cpuctx->task_ctx);
         perf_ctx_disable(&cpuctx->ctx, true);
 
         ctx_sched_out(&cpuctx->ctx, EVENT_ALL|EVENT_CGROUP);
         /*
          * must not be done before ctxswout due
          * to update_cgrp_time_from_cpuctx() in
          * ctx_sched_out()
          */
         cpuctx->cgrp = cgrp;
         /*
          * set cgrp before ctxsw in to allow
          * perf_cgroup_set_timestamp() in ctx_sched_in()
          * to not have to pass task around
          */
         ctx_sched_in(&cpuctx->ctx, EVENT_ALL|EVENT_CGROUP);
 
         perf_ctx_enable(&cpuctx->ctx, true);
         perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
 }
 
 static int perf_cgroup_ensure_storage(struct perf_event *event,
                                 struct cgroup_subsys_state *css)
 {
         struct perf_cpu_context *cpuctx;
         struct perf_event **storage;
         int cpu, heap_size, ret = 0;
 
         /*
          * Allow storage to have sufficient space for an iterator for each
          * possibly nested cgroup plus an iterator for events with no cgroup.
          */
         for (heap_size = 1; css; css = css->parent)
                 heap_size++;
 
         for_each_possible_cpu(cpu) {
                 cpuctx = per_cpu_ptr(&perf_cpu_context, cpu);
                 if (heap_size <= cpuctx->heap_size)
                         continue;
 
                 storage = kmalloc_node(heap_size * sizeof(struct perf_event *),
                                        GFP_KERNEL, cpu_to_node(cpu));
                 if (!storage) {
                         ret = -ENOMEM;
                         break;
                 }
 
                 raw_spin_lock_irq(&cpuctx->ctx.lock);
                 if (cpuctx->heap_size < heap_size) {
                         swap(cpuctx->heap, storage);
                         if (storage == cpuctx->heap_default)
                                 storage = NULL;
                         cpuctx->heap_size = heap_size;
                 }
                 raw_spin_unlock_irq(&cpuctx->ctx.lock);
 
                 kfree(storage);
         }
 
         return ret;
 }
 
 static inline int perf_cgroup_connect(int fd, struct perf_event *event,
                                       struct perf_event_attr *attr,
                                       struct perf_event *group_leader)
 {
         struct perf_cgroup *cgrp;
         struct cgroup_subsys_state *css;
         struct fd f = fdget(fd);
         int ret = 0;
 
         if (!f.file)
                 return -EBADF;
 
         css = css_tryget_online_from_dir(f.file->f_path.dentry,
                                          &perf_event_cgrp_subsys);
         if (IS_ERR(css)) {
                 ret = PTR_ERR(css);
                 goto out;
         }
 
         ret = perf_cgroup_ensure_storage(event, css);
         if (ret)
                 goto out;
 
         cgrp = container_of(css, struct perf_cgroup, css);
         event->cgrp = cgrp;
 
         /*
          * all events in a group must monitor
          * the same cgroup because a task belongs
          * to only one perf cgroup at a time
          */
         if (group_leader && group_leader->cgrp != cgrp) {
                 perf_detach_cgroup(event);
                 ret = -EINVAL;
         }
 out:
         fdput(f);
         return ret;
 }
 
 static inline void
 perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ctx)
 {
         struct perf_cpu_context *cpuctx;
 
         if (!is_cgroup_event(event))
                 return;
 
         event->pmu_ctx->nr_cgroups++;
 
         /*
          * Because cgroup events are always per-cpu events,
          * @ctx == &cpuctx->ctx.
          */
         cpuctx = container_of(ctx, struct perf_cpu_context, ctx);
 
         if (ctx->nr_cgroups++)
                 return;
 
         cpuctx->cgrp = perf_cgroup_from_task(current, ctx);
 }
 
 static inline void
 perf_cgroup_event_disable(struct perf_event *event, struct perf_event_context *ctx)
 {
         struct perf_cpu_context *cpuctx;
 
         if (!is_cgroup_event(event))
                 return;
 
         event->pmu_ctx->nr_cgroups--;
 
         /*
          * Because cgroup events are always per-cpu events,
          * @ctx == &cpuctx->ctx.
          */
         cpuctx = container_of(ctx, struct perf_cpu_context, ctx);
 
         if (--ctx->nr_cgroups)
                 return;
 
         cpuctx->cgrp = NULL;
 }
 
 #else /* !CONFIG_CGROUP_PERF */
 
 static inline bool
 perf_cgroup_match(struct perf_event *event)
 {
         return true;
 }
 
 static inline void perf_detach_cgroup(struct perf_event *event)
 {}
 
 static inline int is_cgroup_event(struct perf_event *event)
 {
         return 0;
 }
 
 static inline void update_cgrp_time_from_event(struct perf_event *event)
 {
 }
 
 static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx,
                                                 bool final)
 {
 }
 
 static inline int perf_cgroup_connect(pid_t pid, struct perf_event *event,
                                       struct perf_event_attr *attr,
                                       struct perf_event *group_leader)
 {
         return -EINVAL;
 }
 
 static inline void
 perf_cgroup_set_timestamp(struct perf_cpu_context *cpuctx)
 {
 }
 
 static inline u64 perf_cgroup_event_time(struct perf_event *event)
 {
         return 0;
 }
 
 static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
 {
         return 0;
 }
 
 static inline void
 perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ctx)
 {
 }
 
 static inline void
 perf_cgroup_event_disable(struct perf_event *event, struct perf_event_context *ctx)
 {
 }
 
 static void perf_cgroup_switch(struct task_struct *task)
 {
 }
 #endif
 
 /*
  * set default to be dependent on timer tick just
  * like original code
  */
 #define PERF_CPU_HRTIMER (1000 / HZ)
 /*
  * function must be called with interrupts disabled
  */
 static enum hrtimer_restart perf_mux_hrtimer_handler(struct hrtimer *hr)
 {
         struct perf_cpu_pmu_context *cpc;
         bool rotations;
 
         lockdep_assert_irqs_disabled();
 
         cpc = container_of(hr, struct perf_cpu_pmu_context, hrtimer);
         rotations = perf_rotate_context(cpc);
 
         raw_spin_lock(&cpc->hrtimer_lock);
         if (rotations)
                 hrtimer_forward_now(hr, cpc->hrtimer_interval);
         else
                 cpc->hrtimer_active = 0;
         raw_spin_unlock(&cpc->hrtimer_lock);
 
         return rotations ? HRTIMER_RESTART : HRTIMER_NORESTART;
 }
 
 static void __perf_mux_hrtimer_init(struct perf_cpu_pmu_context *cpc, int cpu)
 {
         struct hrtimer *timer = &cpc->hrtimer;
         struct pmu *pmu = cpc->epc.pmu;
         u64 interval;
 
         /*
          * check default is sane, if not set then force to
          * default interval (1/tick)
          */
         interval = pmu->hrtimer_interval_ms;
         if (interval < 1)
                 interval = pmu->hrtimer_interval_ms = PERF_CPU_HRTIMER;
 
         cpc->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);
 
         raw_spin_lock_init(&cpc->hrtimer_lock);
         hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
         timer->function = perf_mux_hrtimer_handler;
 }
 
 static int perf_mux_hrtimer_restart(struct perf_cpu_pmu_context *cpc)
 {
         struct hrtimer *timer = &cpc->hrtimer;
         unsigned long flags;
 
         raw_spin_lock_irqsave(&cpc->hrtimer_lock, flags);
         if (!cpc->hrtimer_active) {
                 cpc->hrtimer_active = 1;
                 hrtimer_forward_now(timer, cpc->hrtimer_interval);
                 hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD);
         }
         raw_spin_unlock_irqrestore(&cpc->hrtimer_lock, flags);
 
         return 0;
 }
 
 static int perf_mux_hrtimer_restart_ipi(void *arg)
 {
         return perf_mux_hrtimer_restart(arg);
 }
 
 void perf_pmu_disable(struct pmu *pmu)
 {
         int *count = this_cpu_ptr(pmu->pmu_disable_count);
         if (!(*count)++)
                 pmu->pmu_disable(pmu);
 }
 
 void perf_pmu_enable(struct pmu *pmu)
 {
         int *count = this_cpu_ptr(pmu->pmu_disable_count);
         if (!--(*count))
                 pmu->pmu_enable(pmu);
 }
 
 static void perf_assert_pmu_disabled(struct pmu *pmu)
 {
         WARN_ON_ONCE(*this_cpu_ptr(pmu->pmu_disable_count) == 0);
 }
 
 static void get_ctx(struct perf_event_context *ctx)
 {
         refcount_inc(&ctx->refcount);
 }
 
 static void *alloc_task_ctx_data(struct pmu *pmu)
 {
         if (pmu->task_ctx_cache)
                 return kmem_cache_zalloc(pmu->task_ctx_cache, GFP_KERNEL);
 
         return NULL;
 }
 
 static void free_task_ctx_data(struct pmu *pmu, void *task_ctx_data)
 {
         if (pmu->task_ctx_cache && task_ctx_data)
                 kmem_cache_free(pmu->task_ctx_cache, task_ctx_data);
 }
 
 static void free_ctx(struct rcu_head *head)
 {
         struct perf_event_context *ctx;
 
         ctx = container_of(head, struct perf_event_context, rcu_head);
         kfree(ctx);
 }
 
 static void put_ctx(struct perf_event_context *ctx)
 {
         if (refcount_dec_and_test(&ctx->refcount)) {
                 if (ctx->parent_ctx)
                         put_ctx(ctx->parent_ctx);
                 if (ctx->task && ctx->task != TASK_TOMBSTONE)
                         put_task_struct(ctx->task);
                 call_rcu(&ctx->rcu_head, free_ctx);
         }
 }
 
 /*
  * Because of perf_event::ctx migration in sys_perf_event_open::move_group and
  * perf_pmu_migrate_context() we need some magic.
  *
  * Those places that change perf_event::ctx will hold both
  * perf_event_ctx::mutex of the 'old' and 'new' ctx value.
  *
  * Lock ordering is by mutex address. There are two other sites where
  * perf_event_context::mutex nests and those are:
  *
  *  - perf_event_exit_task_context()    [ child , 0 ]
  *      perf_event_exit_event()
  *        put_event()                   [ parent, 1 ]
  *
  *  - perf_event_init_context()         [ parent, 0 ]
  *      inherit_task_group()
  *        inherit_group()
  *          inherit_event()
  *            perf_event_alloc()
  *              perf_init_event()
  *                perf_try_init_event() [ child , 1 ]
  *
  * While it appears there is an obvious deadlock here -- the parent and child
  * nesting levels are inverted between the two. This is in fact safe because
  * life-time rules separate them. That is an exiting task cannot fork, and a
  * spawning task cannot (yet) exit.
  *
  * But remember that these are parent<->child context relations, and
  * migration does not affect children, therefore these two orderings should not
  * interact.
  *
  * The change in perf_event::ctx does not affect children (as claimed above)
  * because the sys_perf_event_open() case will install a new event and break
  * the ctx parent<->child relation, and perf_pmu_migrate_context() is only
  * concerned with cpuctx and that doesn't have children.
  *
  * The places that change perf_event::ctx will issue:
  *
  *   perf_remove_from_context();
  *   synchronize_rcu();
  *   perf_install_in_context();
  *
  * to affect the change. The remove_from_context() + synchronize_rcu() should
  * quiesce the event, after which we can install it in the new location. This
  * means that only external vectors (perf_fops, prctl) can perturb the event
  * while in transit. Therefore all such accessors should also acquire
  * perf_event_context::mutex to serialize against this.
  *
  * However; because event->ctx can change while we're waiting to acquire
  * ctx->mutex we must be careful and use the below perf_event_ctx_lock()
  * function.
  *
  * Lock order:
  *    exec_update_lock
  *      task_struct::perf_event_mutex
  *        perf_event_context::mutex
  *          perf_event::child_mutex;
  *            perf_event_context::lock
  *          mmap_lock
  *            perf_event::mmap_mutex
  *              perf_buffer::aux_mutex
  *            perf_addr_filters_head::lock
  *
  *    cpu_hotplug_lock
  *      pmus_lock
  *        cpuctx->mutex / perf_event_context::mutex
  */
 static struct perf_event_context *
 perf_event_ctx_lock_nested(struct perf_event *event, int nesting)
 {
         struct perf_event_context *ctx;
 
 again:
         rcu_read_lock();
         ctx = READ_ONCE(event->ctx);
         if (!refcount_inc_not_zero(&ctx->refcount)) {
                 rcu_read_unlock();
                 goto again;
         }
         rcu_read_unlock();
 
         mutex_lock_nested(&ctx->mutex, nesting);
         if (event->ctx != ctx) {
                 mutex_unlock(&ctx->mutex);
                 put_ctx(ctx);
                 goto again;
         }
 
         return ctx;
 }
 
 static inline struct perf_event_context *
 perf_event_ctx_lock(struct perf_event *event)
 {
         return perf_event_ctx_lock_nested(event, 0);
 }
 
 static void perf_event_ctx_unlock(struct perf_event *event,
                                   struct perf_event_context *ctx)
 {
         mutex_unlock(&ctx->mutex);
         put_ctx(ctx);
 }
 
 /*
  * This must be done under the ctx->lock, such as to serialize against
  * context_equiv(), therefore we cannot call put_ctx() since that might end up
  * calling scheduler related locks and ctx->lock nests inside those.
  */
 static __must_check struct perf_event_context *
 unclone_ctx(struct perf_event_context *ctx)
 {
         struct perf_event_context *parent_ctx = ctx->parent_ctx;
 
         lockdep_assert_held(&ctx->lock);
 
         if (parent_ctx)
                 ctx->parent_ctx = NULL;
         ctx->generation++;
 
         return parent_ctx;
 }
 
 static u32 perf_event_pid_type(struct perf_event *event, struct task_struct *p,
                                 enum pid_type type)
 {
         u32 nr;
         /*
          * only top level events have the pid namespace they were created in
          */
         if (event->parent)
                 event = event->parent;
 
         nr = __task_pid_nr_ns(p, type, event->ns);
         /* avoid -1 if it is idle thread or runs in another ns */
         if (!nr && !pid_alive(p))
                 nr = -1;
         return nr;
 }
 
 static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
 {
         return perf_event_pid_type(event, p, PIDTYPE_TGID);
 }
 
 static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
 {
         return perf_event_pid_type(event, p, PIDTYPE_PID);
 }
 
 /*
  * If we inherit events we want to return the parent event id
  * to userspace.
  */
 static u64 primary_event_id(struct perf_event *event)
 {
         u64 id = event->id;
 
         if (event->parent)
                 id = event->parent->id;
 
         return id;
 }
 
 /*
  * Get the perf_event_context for a task and lock it.
  *
  * This has to cope with the fact that until it is locked,
  * the context could get moved to another task.
  */
 static struct perf_event_context *
 perf_lock_task_context(struct task_struct *task, unsigned long *flags)
 {
         struct perf_event_context *ctx;
 
 retry:
         /*
          * One of the few rules of preemptible RCU is that one cannot do
          * rcu_read_unlock() while holding a scheduler (or nested) lock when
          * part of the read side critical section was irqs-enabled -- see
          * rcu_read_unlock_special().
          *
          * Since ctx->lock nests under rq->lock we must ensure the entire read
          * side critical section has interrupts disabled.
          */
         local_irq_save(*flags);
         rcu_read_lock();
         ctx = rcu_dereference(task->perf_event_ctxp);
         if (ctx) {
                 /*
                  * If this context is a clone of another, it might
                  * get swapped for another underneath us by
                  * perf_event_task_sched_out, though the
                  * rcu_read_lock() protects us from any context
                  * getting freed.  Lock the context and check if it
                  * got swapped before we could get the lock, and retry
                  * if so.  If we locked the right context, then it
                  * can't get swapped on us any more.
                  */
                 raw_spin_lock(&ctx->lock);
                 if (ctx != rcu_dereference(task->perf_event_ctxp)) {
                         raw_spin_unlock(&ctx->lock);
                         rcu_read_unlock();
                         local_irq_restore(*flags);
                         goto retry;
                 }
 
                 if (ctx->task == TASK_TOMBSTONE ||
                     !refcount_inc_not_zero(&ctx->refcount)) {
                         raw_spin_unlock(&ctx->lock);
                         ctx = NULL;
                 } else {
                         WARN_ON_ONCE(ctx->task != task);
                 }
         }
         rcu_read_unlock();
         if (!ctx)
                 local_irq_restore(*flags);
         return ctx;
 }
 
 /*
  * Get the context for a task and increment its pin_count so it
  * can't get swapped to another task.  This also increments its
  * reference count so that the context can't get freed.
  */
 static struct perf_event_context *
 perf_pin_task_context(struct task_struct *task)
 {
         struct perf_event_context *ctx;
         unsigned long flags;
 
         ctx = perf_lock_task_context(task, &flags);
         if (ctx) {
                 ++ctx->pin_count;
                 raw_spin_unlock_irqrestore(&ctx->lock, flags);
         }
         return ctx;
 }
 
 static void perf_unpin_context(struct perf_event_context *ctx)
 {
         unsigned long flags;
 
         raw_spin_lock_irqsave(&ctx->lock, flags);
         --ctx->pin_count;
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
 }
 
 /*
  * Update the record of the current time in a context.
  */
 static void __update_context_time(struct perf_event_context *ctx, bool adv)
 {
         u64 now = perf_clock();
 
         lockdep_assert_held(&ctx->lock);
 
         if (adv)
                 ctx->time += now - ctx->timestamp;
         ctx->timestamp = now;
 
         /*
          * The above: time' = time + (now - timestamp), can be re-arranged
          * into: time` = now + (time - timestamp), which gives a single value
          * offset to compute future time without locks on.
          *
          * See perf_event_time_now(), which can be used from NMI context where
          * it's (obviously) not possible to acquire ctx->lock in order to read
          * both the above values in a consistent manner.
          */
         WRITE_ONCE(ctx->timeoffset, ctx->time - ctx->timestamp);
 }
 
 static void update_context_time(struct perf_event_context *ctx)
 {
         __update_context_time(ctx, true);
 }
 
 static u64 perf_event_time(struct perf_event *event)
 {
         struct perf_event_context *ctx = event->ctx;
 
         if (unlikely(!ctx))
                 return 0;
 
         if (is_cgroup_event(event))
                 return perf_cgroup_event_time(event);
 
         return ctx->time;
 }
 
 static u64 perf_event_time_now(struct perf_event *event, u64 now)
 {
         struct perf_event_context *ctx = event->ctx;
 
         if (unlikely(!ctx))
                 return 0;
 
         if (is_cgroup_event(event))
                 return perf_cgroup_event_time_now(event, now);
 
         if (!(__load_acquire(&ctx->is_active) & EVENT_TIME))
                 return ctx->time;
 
         now += READ_ONCE(ctx->timeoffset);
         return now;
 }
 
 static enum event_type_t get_event_type(struct perf_event *event)
 {
         struct perf_event_context *ctx = event->ctx;
         enum event_type_t event_type;
 
         lockdep_assert_held(&ctx->lock);
 
         /*
          * It's 'group type', really, because if our group leader is
          * pinned, so are we.
          */
         if (event->group_leader != event)
                 event = event->group_leader;
 
         event_type = event->attr.pinned ? EVENT_PINNED : EVENT_FLEXIBLE;
         if (!ctx->task)
                 event_type |= EVENT_CPU;
 
         return event_type;
 }
 
 /*
  * Helper function to initialize event group nodes.
  */
 static void init_event_group(struct perf_event *event)
 {
         RB_CLEAR_NODE(&event->group_node);
         event->group_index = 0;
 }
 
 /*
  * Extract pinned or flexible groups from the context
  * based on event attrs bits.
  */
 static struct perf_event_groups *
 get_event_groups(struct perf_event *event, struct perf_event_context *ctx)
 {
         if (event->attr.pinned)
                 return &ctx->pinned_groups;
         else
                 return &ctx->flexible_groups;
 }
 
 /*
  * Helper function to initializes perf_event_group trees.
  */
 static void perf_event_groups_init(struct perf_event_groups *groups)
 {
         groups->tree = RB_ROOT;
         groups->index = 0;
 }
 
 static inline struct cgroup *event_cgroup(const struct perf_event *event)
 {
         struct cgroup *cgroup = NULL;
 
 #ifdef CONFIG_CGROUP_PERF
         if (event->cgrp)
                 cgroup = event->cgrp->css.cgroup;
 #endif
 
         return cgroup;
 }
 
 /*
  * Compare function for event groups;
  *
  * Implements complex key that first sorts by CPU and then by virtual index
  * which provides ordering when rotating groups for the same CPU.
  */
 static __always_inline int
 perf_event_groups_cmp(const int left_cpu, const struct pmu *left_pmu,
                       const struct cgroup *left_cgroup, const u64 left_group_index,
                       const struct perf_event *right)
 {
         if (left_cpu < right->cpu)
                 return -1;
         if (left_cpu > right->cpu)
                 return 1;
 
         if (left_pmu) {
                 if (left_pmu < right->pmu_ctx->pmu)
                         return -1;
                 if (left_pmu > right->pmu_ctx->pmu)
                         return 1;
         }
 
 #ifdef CONFIG_CGROUP_PERF
         {
                 const struct cgroup *right_cgroup = event_cgroup(right);
 
                 if (left_cgroup != right_cgroup) {
                         if (!left_cgroup) {
                                 /*
                                  * Left has no cgroup but right does, no
                                  * cgroups come first.
                                  */
                                 return -1;
                         }
                         if (!right_cgroup) {
                                 /*
                                  * Right has no cgroup but left does, no
                                  * cgroups come first.
                                  */
                                 return 1;
                         }
                         /* Two dissimilar cgroups, order by id. */
                         if (cgroup_id(left_cgroup) < cgroup_id(right_cgroup))
                                 return -1;
 
                         return 1;
                 }
         }
 #endif
 
         if (left_group_index < right->group_index)
                 return -1;
         if (left_group_index > right->group_index)
                 return 1;
 
         return 0;
 }
 
 #define __node_2_pe(node) \
         rb_entry((node), struct perf_event, group_node)
 
 static inline bool __group_less(struct rb_node *a, const struct rb_node *b)
 {
         struct perf_event *e = __node_2_pe(a);
         return perf_event_groups_cmp(e->cpu, e->pmu_ctx->pmu, event_cgroup(e),
                                      e->group_index, __node_2_pe(b)) < 0;
 }
 
 struct __group_key {
         int cpu;
         struct pmu *pmu;
         struct cgroup *cgroup;
 };
 
 static inline int __group_cmp(const void *key, const struct rb_node *node)
 {
         const struct __group_key *a = key;
         const struct perf_event *b = __node_2_pe(node);
 
         /* partial/subtree match: @cpu, @pmu, @cgroup; ignore: @group_index */
         return perf_event_groups_cmp(a->cpu, a->pmu, a->cgroup, b->group_index, b);
 }
 
 static inline int
 __group_cmp_ignore_cgroup(const void *key, const struct rb_node *node)
 {
         const struct __group_key *a = key;
         const struct perf_event *b = __node_2_pe(node);
 
         /* partial/subtree match: @cpu, @pmu, ignore: @cgroup, @group_index */
         return perf_event_groups_cmp(a->cpu, a->pmu, event_cgroup(b),
                                      b->group_index, b);
 }
 
 /*
  * Insert @event into @groups' tree; using
  *   {@event->cpu, @event->pmu_ctx->pmu, event_cgroup(@event), ++@groups->index}
  * as key. This places it last inside the {cpu,pmu,cgroup} subtree.
  */
 static void
 perf_event_groups_insert(struct perf_event_groups *groups,
                          struct perf_event *event)
 {
         event->group_index = ++groups->index;
 
         rb_add(&event->group_node, &groups->tree, __group_less);
 }
 
 /*
  * Helper function to insert event into the pinned or flexible groups.
  */
 static void
 add_event_to_groups(struct perf_event *event, struct perf_event_context *ctx)
 {
         struct perf_event_groups *groups;
 
         groups = get_event_groups(event, ctx);
         perf_event_groups_insert(groups, event);
 }
 
 /*
  * Delete a group from a tree.
  */
 static void
 perf_event_groups_delete(struct perf_event_groups *groups,
                          struct perf_event *event)
 {
         WARN_ON_ONCE(RB_EMPTY_NODE(&event->group_node) ||
                      RB_EMPTY_ROOT(&groups->tree));
 
         rb_erase(&event->group_node, &groups->tree);
         init_event_group(event);
 }
 
 /*
  * Helper function to delete event from its groups.
  */
 static void
 del_event_from_groups(struct perf_event *event, struct perf_event_context *ctx)
 {
         struct perf_event_groups *groups;
 
         groups = get_event_groups(event, ctx);
         perf_event_groups_delete(groups, event);
 }
 
 /*
  * Get the leftmost event in the {cpu,pmu,cgroup} subtree.
  */
 static struct perf_event *
 perf_event_groups_first(struct perf_event_groups *groups, int cpu,
                         struct pmu *pmu, struct cgroup *cgrp)
 {
         struct __group_key key = {
                 .cpu = cpu,
                 .pmu = pmu,
                 .cgroup = cgrp,
         };
         struct rb_node *node;
 
         node = rb_find_first(&key, &groups->tree, __group_cmp);
         if (node)
                 return __node_2_pe(node);
 
         return NULL;
 }
 
 static struct perf_event *
 perf_event_groups_next(struct perf_event *event, struct pmu *pmu)
 {
         struct __group_key key = {
                 .cpu = event->cpu,
                 .pmu = pmu,
                 .cgroup = event_cgroup(event),
         };
         struct rb_node *next;
 
         next = rb_next_match(&key, &event->group_node, __group_cmp);
         if (next)
                 return __node_2_pe(next);
 
         return NULL;
 }
 
 #define perf_event_groups_for_cpu_pmu(event, groups, cpu, pmu)          \
         for (event = perf_event_groups_first(groups, cpu, pmu, NULL);   \
              event; event = perf_event_groups_next(event, pmu))
 
 /*
  * Iterate through the whole groups tree.
  */
 #define perf_event_groups_for_each(event, groups)                       \
         for (event = rb_entry_safe(rb_first(&((groups)->tree)),         \
                                 typeof(*event), group_node); event;     \
                 event = rb_entry_safe(rb_next(&event->group_node),      \
                                 typeof(*event), group_node))
 
 /*
  * Add an event from the lists for its context.
  * Must be called with ctx->mutex and ctx->lock held.
  */
 static void
 list_add_event(struct perf_event *event, struct perf_event_context *ctx)
 {
         lockdep_assert_held(&ctx->lock);
 
         WARN_ON_ONCE(event->attach_state & PERF_ATTACH_CONTEXT);
         event->attach_state |= PERF_ATTACH_CONTEXT;
 
         event->tstamp = perf_event_time(event);
 
         /*
          * If we're a stand alone event or group leader, we go to the context
          * list, group events are kept attached to the group so that
          * perf_group_detach can, at all times, locate all siblings.
          */
         if (event->group_leader == event) {
                 event->group_caps = event->event_caps;
                 add_event_to_groups(event, ctx);
         }
 
         list_add_rcu(&event->event_entry, &ctx->event_list);
         ctx->nr_events++;
         if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
                 ctx->nr_user++;
         if (event->attr.inherit_stat)
                 ctx->nr_stat++;
 
         if (event->state > PERF_EVENT_STATE_OFF)
                 perf_cgroup_event_enable(event, ctx);
 
         ctx->generation++;
         event->pmu_ctx->nr_events++;
 }
 
 /*
  * Initialize event state based on the perf_event_attr::disabled.
  */
 static inline void perf_event__state_init(struct perf_event *event)
 {
         event->state = event->attr.disabled ? PERF_EVENT_STATE_OFF :
                                               PERF_EVENT_STATE_INACTIVE;
 }
 
 static int __perf_event_read_size(u64 read_format, int nr_siblings)
 {
         int entry = sizeof(u64); /* value */
         int size = 0;
         int nr = 1;
 
         if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
                 size += sizeof(u64);
 
         if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
                 size += sizeof(u64);
 
         if (read_format & PERF_FORMAT_ID)
                 entry += sizeof(u64);
 
         if (read_format & PERF_FORMAT_LOST)
                 entry += sizeof(u64);
 
         if (read_format & PERF_FORMAT_GROUP) {
                 nr += nr_siblings;
                 size += sizeof(u64);
         }
 
         /*
          * Since perf_event_validate_size() limits this to 16k and inhibits
          * adding more siblings, this will never overflow.
          */
         return size + nr * entry;
 }
 
 static void __perf_event_header_size(struct perf_event *event, u64 sample_type)
 {
         struct perf_sample_data *data;
         u16 size = 0;
 
         if (sample_type & PERF_SAMPLE_IP)
                 size += sizeof(data->ip);
 
         if (sample_type & PERF_SAMPLE_ADDR)
                 size += sizeof(data->addr);
 
         if (sample_type & PERF_SAMPLE_PERIOD)
                 size += sizeof(data->period);
 
         if (sample_type & PERF_SAMPLE_WEIGHT_TYPE)
                 size += sizeof(data->weight.full);
 
         if (sample_type & PERF_SAMPLE_READ)
                 size += event->read_size;
 
         if (sample_type & PERF_SAMPLE_DATA_SRC)
                 size += sizeof(data->data_src.val);
 
         if (sample_type & PERF_SAMPLE_TRANSACTION)
                 size += sizeof(data->txn);
 
         if (sample_type & PERF_SAMPLE_PHYS_ADDR)
                 size += sizeof(data->phys_addr);
 
         if (sample_type & PERF_SAMPLE_CGROUP)
                 size += sizeof(data->cgroup);
 
         if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
                 size += sizeof(data->data_page_size);
 
         if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
                 size += sizeof(data->code_page_size);
 
         event->header_size = size;
 }
 
 /*
  * Called at perf_event creation and when events are attached/detached from a
  * group.
  */
 static void perf_event__header_size(struct perf_event *event)
 {
         event->read_size =
                 __perf_event_read_size(event->attr.read_format,
                                        event->group_leader->nr_siblings);
         __perf_event_header_size(event, event->attr.sample_type);
 }
 
 static void perf_event__id_header_size(struct perf_event *event)
 {
         struct perf_sample_data *data;
         u64 sample_type = event->attr.sample_type;
         u16 size = 0;
 
         if (sample_type & PERF_SAMPLE_TID)
                 size += sizeof(data->tid_entry);
 
         if (sample_type & PERF_SAMPLE_TIME)
                 size += sizeof(data->time);
 
         if (sample_type & PERF_SAMPLE_IDENTIFIER)
                 size += sizeof(data->id);
 
         if (sample_type & PERF_SAMPLE_ID)
                 size += sizeof(data->id);
 
         if (sample_type & PERF_SAMPLE_STREAM_ID)
                 size += sizeof(data->stream_id);
 
         if (sample_type & PERF_SAMPLE_CPU)
                 size += sizeof(data->cpu_entry);
 
         event->id_header_size = size;
 }
 
 /*
  * Check that adding an event to the group does not result in anybody
  * overflowing the 64k event limit imposed by the output buffer.
  *
  * Specifically, check that the read_size for the event does not exceed 16k,
  * read_size being the one term that grows with groups size. Since read_size
  * depends on per-event read_format, also (re)check the existing events.
  *
  * This leaves 48k for the constant size fields and things like callchains,
  * branch stacks and register sets.
  */
 static bool perf_event_validate_size(struct perf_event *event)
 {
         struct perf_event *sibling, *group_leader = event->group_leader;
 
         if (__perf_event_read_size(event->attr.read_format,
                                    group_leader->nr_siblings + 1) > 16*1024)
                 return false;
 
         if (__perf_event_read_size(group_leader->attr.read_format,
                                    group_leader->nr_siblings + 1) > 16*1024)
                 return false;
 
         /*
          * When creating a new group leader, group_leader->ctx is initialized
          * after the size has been validated, but we cannot safely use
          * for_each_sibling_event() until group_leader->ctx is set. A new group
          * leader cannot have any siblings yet, so we can safely skip checking
          * the non-existent siblings.
          */
         if (event == group_leader)
                 return true;
 
         for_each_sibling_event(sibling, group_leader) {
                 if (__perf_event_read_size(sibling->attr.read_format,
                                            group_leader->nr_siblings + 1) > 16*1024)
                         return false;
         }
 
         return true;
 }
 
 static void perf_group_attach(struct perf_event *event)
 {
         struct perf_event *group_leader = event->group_leader, *pos;
 
         lockdep_assert_held(&event->ctx->lock);
 
         /*
          * We can have double attach due to group movement (move_group) in
          * perf_event_open().
          */
         if (event->attach_state & PERF_ATTACH_GROUP)
                 return;
 
         event->attach_state |= PERF_ATTACH_GROUP;
 
         if (group_leader == event)
                 return;
 
         WARN_ON_ONCE(group_leader->ctx != event->ctx);
 
         group_leader->group_caps &= event->event_caps;
 
         list_add_tail(&event->sibling_list, &group_leader->sibling_list);
         group_leader->nr_siblings++;
         group_leader->group_generation++;
 
         perf_event__header_size(group_leader);
 
         for_each_sibling_event(pos, group_leader)
                 perf_event__header_size(pos);
 }
 
 /*
  * Remove an event from the lists for its context.
  * Must be called with ctx->mutex and ctx->lock held.
  */
 static void
 list_del_event(struct perf_event *event, struct perf_event_context *ctx)
 {
         WARN_ON_ONCE(event->ctx != ctx);
         lockdep_assert_held(&ctx->lock);
 
         /*
          * We can have double detach due to exit/hot-unplug + close.
          */
         if (!(event->attach_state & PERF_ATTACH_CONTEXT))
                 return;
 
         event->attach_state &= ~PERF_ATTACH_CONTEXT;
 
         ctx->nr_events--;
         if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
                 ctx->nr_user--;
         if (event->attr.inherit_stat)
                 ctx->nr_stat--;
 
         list_del_rcu(&event->event_entry);
 
         if (event->group_leader == event)
                 del_event_from_groups(event, ctx);
 
         /*
          * If event was in error state, then keep it
          * that way, otherwise bogus counts will be
          * returned on read(). The only way to get out
          * of error state is by explicit re-enabling
          * of the event
          */
         if (event->state > PERF_EVENT_STATE_OFF) {
                 perf_cgroup_event_disable(event, ctx);
                 perf_event_set_state(event, PERF_EVENT_STATE_OFF);
         }
 
         ctx->generation++;
         event->pmu_ctx->nr_events--;
 }
 
 static int
 perf_aux_output_match(struct perf_event *event, struct perf_event *aux_event)
 {
         if (!has_aux(aux_event))
                 return 0;
 
         if (!event->pmu->aux_output_match)
                 return 0;
 
         return event->pmu->aux_output_match(aux_event);
 }
 
 static void put_event(struct perf_event *event);
 static void event_sched_out(struct perf_event *event,
                             struct perf_event_context *ctx);
 
 static void perf_put_aux_event(struct perf_event *event)
 {
         struct perf_event_context *ctx = event->ctx;
         struct perf_event *iter;
 
         /*
          * If event uses aux_event tear down the link
          */
         if (event->aux_event) {
                 iter = event->aux_event;
                 event->aux_event = NULL;
                 put_event(iter);
                 return;
         }
 
         /*
          * If the event is an aux_event, tear down all links to
          * it from other events.
          */
         for_each_sibling_event(iter, event->group_leader) {
                 if (iter->aux_event != event)
                         continue;
 
                 iter->aux_event = NULL;
                 put_event(event);
 
                 /*
                  * If it's ACTIVE, schedule it out and put it into ERROR
                  * state so that we don't try to schedule it again. Note
                  * that perf_event_enable() will clear the ERROR status.
                  */
                 event_sched_out(iter, ctx);
                 perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
         }
 }
 
 static bool perf_need_aux_event(struct perf_event *event)
 {
         return !!event->attr.aux_output || !!event->attr.aux_sample_size;
 }
 
 static int perf_get_aux_event(struct perf_event *event,
                               struct perf_event *group_leader)
 {
         /*
          * Our group leader must be an aux event if we want to be
          * an aux_output. This way, the aux event will precede its
          * aux_output events in the group, and therefore will always
          * schedule first.
          */
         if (!group_leader)
                 return 0;
 
         /*
          * aux_output and aux_sample_size are mutually exclusive.
          */
         if (event->attr.aux_output && event->attr.aux_sample_size)
                 return 0;
 
         if (event->attr.aux_output &&
             !perf_aux_output_match(event, group_leader))
                 return 0;
 
         if (event->attr.aux_sample_size && !group_leader->pmu->snapshot_aux)
                 return 0;
 
         if (!atomic_long_inc_not_zero(&group_leader->refcount))
                 return 0;
 
         /*
          * Link aux_outputs to their aux event; this is undone in
          * perf_group_detach() by perf_put_aux_event(). When the
          * group in torn down, the aux_output events loose their
          * link to the aux_event and can't schedule any more.
          */
         event->aux_event = group_leader;
 
         return 1;
 }
 
 static inline struct list_head *get_event_list(struct perf_event *event)
 {
         return event->attr.pinned ? &event->pmu_ctx->pinned_active :
                                     &event->pmu_ctx->flexible_active;
 }
 
 /*
  * Events that have PERF_EV_CAP_SIBLING require being part of a group and
  * cannot exist on their own, schedule them out and move them into the ERROR
  * state. Also see _perf_event_enable(), it will not be able to recover
  * this ERROR state.
  */
 static inline void perf_remove_sibling_event(struct perf_event *event)
 {
         event_sched_out(event, event->ctx);
         perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
 }
 
 static void perf_group_detach(struct perf_event *event)
 {
         struct perf_event *leader = event->group_leader;
         struct perf_event *sibling, *tmp;
         struct perf_event_context *ctx = event->ctx;
 
         lockdep_assert_held(&ctx->lock);
 
         /*
          * We can have double detach due to exit/hot-unplug + close.
          */
         if (!(event->attach_state & PERF_ATTACH_GROUP))
                 return;
 
         event->attach_state &= ~PERF_ATTACH_GROUP;
 
         perf_put_aux_event(event);
 
         /*
          * If this is a sibling, remove it from its group.
          */
         if (leader != event) {
                 list_del_init(&event->sibling_list);
                 event->group_leader->nr_siblings--;
                 event->group_leader->group_generation++;
                 goto out;
         }
 
         /*
          * If this was a group event with sibling events then
          * upgrade the siblings to singleton events by adding them
          * to whatever list we are on.
          */
         list_for_each_entry_safe(sibling, tmp, &event->sibling_list, sibling_list) {
 
                 if (sibling->event_caps & PERF_EV_CAP_SIBLING)
                         perf_remove_sibling_event(sibling);
 
                 sibling->group_leader = sibling;
                 list_del_init(&sibling->sibling_list);
 
                 /* Inherit group flags from the previous leader */
                 sibling->group_caps = event->group_caps;
 
                 if (sibling->attach_state & PERF_ATTACH_CONTEXT) {
                         add_event_to_groups(sibling, event->ctx);
 
                         if (sibling->state == PERF_EVENT_STATE_ACTIVE)
                                 list_add_tail(&sibling->active_list, get_event_list(sibling));
                 }
 
                 WARN_ON_ONCE(sibling->ctx != event->ctx);
         }
 
 out:
         for_each_sibling_event(tmp, leader)
                 perf_event__header_size(tmp);
 
         perf_event__header_size(leader);
 }
 
 static void sync_child_event(struct perf_event *child_event);
 
 static void perf_child_detach(struct perf_event *event)
 {
         struct perf_event *parent_event = event->parent;
 
         if (!(event->attach_state & PERF_ATTACH_CHILD))
                 return;
 
         event->attach_state &= ~PERF_ATTACH_CHILD;
 
         if (WARN_ON_ONCE(!parent_event))
                 return;
 
         lockdep_assert_held(&parent_event->child_mutex);
 
         sync_child_event(event);
         list_del_init(&event->child_list);
 }
 
 static bool is_orphaned_event(struct perf_event *event)
 {
         return event->state == PERF_EVENT_STATE_DEAD;
 }
 
 static inline int
 event_filter_match(struct perf_event *event)
 {
         return (event->cpu == -1 || event->cpu == smp_processor_id()) &&
                perf_cgroup_match(event);
 }
 
 static void
 event_sched_out(struct perf_event *event, struct perf_event_context *ctx)
 {
         struct perf_event_pmu_context *epc = event->pmu_ctx;
         struct perf_cpu_pmu_context *cpc = this_cpu_ptr(epc->pmu->cpu_pmu_context);
         enum perf_event_state state = PERF_EVENT_STATE_INACTIVE;
 
         // XXX cpc serialization, probably per-cpu IRQ disabled
 
         WARN_ON_ONCE(event->ctx != ctx);
         lockdep_assert_held(&ctx->lock);
 
         if (event->state != PERF_EVENT_STATE_ACTIVE)
                 return;
 
         /*
          * Asymmetry; we only schedule events _IN_ through ctx_sched_in(), but
          * we can schedule events _OUT_ individually through things like
          * __perf_remove_from_context().
          */
         list_del_init(&event->active_list);
 
         perf_pmu_disable(event->pmu);
 
         event->pmu->del(event, 0);
         event->oncpu = -1;
 
         if (event->pending_disable) {
                 event->pending_disable = 0;
                 perf_cgroup_event_disable(event, ctx);
                 state = PERF_EVENT_STATE_OFF;
         }
 
         perf_event_set_state(event, state);
 
         if (!is_software_event(event))
                 cpc->active_oncpu--;
         if (event->attr.freq && event->attr.sample_freq) {
                 ctx->nr_freq--;
                 epc->nr_freq--;
         }
         if (event->attr.exclusive || !cpc->active_oncpu)
                 cpc->exclusive = 0;
 
         perf_pmu_enable(event->pmu);
 }
 
 static void
 group_sched_out(struct perf_event *group_event, struct perf_event_context *ctx)
 {
         struct perf_event *event;
 
         if (group_event->state != PERF_EVENT_STATE_ACTIVE)
                 return;
 
         perf_assert_pmu_disabled(group_event->pmu_ctx->pmu);
 
         event_sched_out(group_event, ctx);
 
         /*
          * Schedule out siblings (if any):
          */
         for_each_sibling_event(event, group_event)
                 event_sched_out(event, ctx);
 }
 
 #define DETACH_GROUP    0x01UL
 #define DETACH_CHILD    0x02UL
 #define DETACH_DEAD     0x04UL
 
 /*
  * Cross CPU call to remove a performance event
  *
  * We disable the event on the hardware level first. After that we
  * remove it from the context list.
  */
 static void
 __perf_remove_from_context(struct perf_event *event,
                            struct perf_cpu_context *cpuctx,
                            struct perf_event_context *ctx,
                            void *info)
 {
         struct perf_event_pmu_context *pmu_ctx = event->pmu_ctx;
         unsigned long flags = (unsigned long)info;
 
         if (ctx->is_active & EVENT_TIME) {
                 update_context_time(ctx);
                 update_cgrp_time_from_cpuctx(cpuctx, false);
         }
 
         /*
          * Ensure event_sched_out() switches to OFF, at the very least
          * this avoids raising perf_pending_task() at this time.
          */
         if (flags & DETACH_DEAD)
                 event->pending_disable = 1;
         event_sched_out(event, ctx);
         if (flags & DETACH_GROUP)
                 perf_group_detach(event);
         if (flags & DETACH_CHILD)
                 perf_child_detach(event);
         list_del_event(event, ctx);
         if (flags & DETACH_DEAD)
                 event->state = PERF_EVENT_STATE_DEAD;
 
         if (!pmu_ctx->nr_events) {
                 pmu_ctx->rotate_necessary = 0;
 
                 if (ctx->task && ctx->is_active) {
                         struct perf_cpu_pmu_context *cpc;
 
                         cpc = this_cpu_ptr(pmu_ctx->pmu->cpu_pmu_context);
                         WARN_ON_ONCE(cpc->task_epc && cpc->task_epc != pmu_ctx);
                         cpc->task_epc = NULL;
                 }
         }
 
         if (!ctx->nr_events && ctx->is_active) {
                 if (ctx == &cpuctx->ctx)
                         update_cgrp_time_from_cpuctx(cpuctx, true);
 
                 ctx->is_active = 0;
                 if (ctx->task) {
                         WARN_ON_ONCE(cpuctx->task_ctx != ctx);
                         cpuctx->task_ctx = NULL;
                 }
         }
 }
 
 /*
  * Remove the event from a task's (or a CPU's) list of events.
  *
  * If event->ctx is a cloned context, callers must make sure that
  * every task struct that event->ctx->task could possibly point to
  * remains valid.  This is OK when called from perf_release since
  * that only calls us on the top-level context, which can't be a clone.
  * When called from perf_event_exit_task, it's OK because the
  * context has been detached from its task.
  */
 static void perf_remove_from_context(struct perf_event *event, unsigned long flags)
 {
         struct perf_event_context *ctx = event->ctx;
 
         lockdep_assert_held(&ctx->mutex);
 
         /*
          * Because of perf_event_exit_task(), perf_remove_from_context() ought
          * to work in the face of TASK_TOMBSTONE, unlike every other
          * event_function_call() user.
          */
         raw_spin_lock_irq(&ctx->lock);
         if (!ctx->is_active) {
                 __perf_remove_from_context(event, this_cpu_ptr(&perf_cpu_context),
                                            ctx, (void *)flags);
                 raw_spin_unlock_irq(&ctx->lock);
                 return;
         }
         raw_spin_unlock_irq(&ctx->lock);
 
         event_function_call(event, __perf_remove_from_context, (void *)flags);
 }
 
 /*
  * Cross CPU call to disable a performance event
  */
 static void __perf_event_disable(struct perf_event *event,
                                  struct perf_cpu_context *cpuctx,
                                  struct perf_event_context *ctx,
                                  void *info)
 {
         if (event->state < PERF_EVENT_STATE_INACTIVE)
                 return;
 
         if (ctx->is_active & EVENT_TIME) {
                 update_context_time(ctx);
                 update_cgrp_time_from_event(event);
         }
 
         perf_pmu_disable(event->pmu_ctx->pmu);
 
         if (event == event->group_leader)
                 group_sched_out(event, ctx);
         else
                 event_sched_out(event, ctx);
 
         perf_event_set_state(event, PERF_EVENT_STATE_OFF);
         perf_cgroup_event_disable(event, ctx);
 
         perf_pmu_enable(event->pmu_ctx->pmu);
 }
 
 /*
  * Disable an event.
  *
  * If event->ctx is a cloned context, callers must make sure that
  * every task struct that event->ctx->task could possibly point to
  * remains valid.  This condition is satisfied when called through
  * perf_event_for_each_child or perf_event_for_each because they
  * hold the top-level event's child_mutex, so any descendant that
  * goes to exit will block in perf_event_exit_event().
  *
  * When called from perf_pending_disable it's OK because event->ctx
  * is the current context on this CPU and preemption is disabled,
  * hence we can't get into perf_event_task_sched_out for this context.
  */
 static void _perf_event_disable(struct perf_event *event)
 {
         struct perf_event_context *ctx = event->ctx;
 
         raw_spin_lock_irq(&ctx->lock);
         if (event->state <= PERF_EVENT_STATE_OFF) {
                 raw_spin_unlock_irq(&ctx->lock);
                 return;
         }
         raw_spin_unlock_irq(&ctx->lock);
 
         event_function_call(event, __perf_event_disable, NULL);
 }
 
 void perf_event_disable_local(struct perf_event *event)
 {
         event_function_local(event, __perf_event_disable, NULL);
 }
 
 /*
  * Strictly speaking kernel users cannot create groups and therefore this
  * interface does not need the perf_event_ctx_lock() magic.
  */
 void perf_event_disable(struct perf_event *event)
 {
         struct perf_event_context *ctx;
 
         ctx = perf_event_ctx_lock(event);
         _perf_event_disable(event);
         perf_event_ctx_unlock(event, ctx);
 }
 EXPORT_SYMBOL_GPL(perf_event_disable);
 
 void perf_event_disable_inatomic(struct perf_event *event)
 {
         event->pending_disable = 1;
         irq_work_queue(&event->pending_disable_irq);
 }
 
 #define MAX_INTERRUPTS (~0ULL)
 
 static void perf_log_throttle(struct perf_event *event, int enable);
 static void perf_log_itrace_start(struct perf_event *event);
 
 static int
 event_sched_in(struct perf_event *event, struct perf_event_context *ctx)
 {
         struct perf_event_pmu_context *epc = event->pmu_ctx;
         struct perf_cpu_pmu_context *cpc = this_cpu_ptr(epc->pmu->cpu_pmu_context);
         int ret = 0;
 
         WARN_ON_ONCE(event->ctx != ctx);
 
         lockdep_assert_held(&ctx->lock);
 
         if (event->state <= PERF_EVENT_STATE_OFF)
                 return 0;
 
         WRITE_ONCE(event->oncpu, smp_processor_id());
         /*
          * Order event::oncpu write to happen before the ACTIVE state is
          * visible. This allows perf_event_{stop,read}() to observe the correct
          * ->oncpu if it sees ACTIVE.
          */
         smp_wmb();
         perf_event_set_state(event, PERF_EVENT_STATE_ACTIVE);
 
         /*
          * Unthrottle events, since we scheduled we might have missed several
          * ticks already, also for a heavily scheduling task there is little
          * guarantee it'll get a tick in a timely manner.
          */
         if (unlikely(event->hw.interrupts == MAX_INTERRUPTS)) {
                 perf_log_throttle(event, 1);
                 event->hw.interrupts = 0;
         }
 
         perf_pmu_disable(event->pmu);
 
         perf_log_itrace_start(event);
 
         if (event->pmu->add(event, PERF_EF_START)) {
                 perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
                 event->oncpu = -1;
                 ret = -EAGAIN;
                 goto out;
         }
 
         if (!is_software_event(event))
                 cpc->active_oncpu++;
         if (event->attr.freq && event->attr.sample_freq) {
                 ctx->nr_freq++;
                 epc->nr_freq++;
         }
         if (event->attr.exclusive)
                 cpc->exclusive = 1;
 
 out:
         perf_pmu_enable(event->pmu);
 
         return ret;
 }
 
 static int
 group_sched_in(struct perf_event *group_event, struct perf_event_context *ctx)
 {
         struct perf_event *event, *partial_group = NULL;
         struct pmu *pmu = group_event->pmu_ctx->pmu;
 
         if (group_event->state == PERF_EVENT_STATE_OFF)
                 return 0;
 
         pmu->start_txn(pmu, PERF_PMU_TXN_ADD);
 
         if (event_sched_in(group_event, ctx))
                 goto error;
 
         /*
          * Schedule in siblings as one group (if any):
          */
         for_each_sibling_event(event, group_event) {
                 if (event_sched_in(event, ctx)) {
                         partial_group = event;
                         goto group_error;
                 }
         }
 
         if (!pmu->commit_txn(pmu))
                 return 0;
 
 group_error:
         /*
          * Groups can be scheduled in as one unit only, so undo any
          * partial group before returning:
          * The events up to the failed event are scheduled out normally.
          */
         for_each_sibling_event(event, group_event) {
                 if (event == partial_group)
                         break;
 
                 event_sched_out(event, ctx);
         }
         event_sched_out(group_event, ctx);
 
 error:
         pmu->cancel_txn(pmu);
         return -EAGAIN;
 }
 
 /*
  * Work out whether we can put this event group on the CPU now.
  */
 static int group_can_go_on(struct perf_event *event, int can_add_hw)
 {
         struct perf_event_pmu_context *epc = event->pmu_ctx;
         struct perf_cpu_pmu_context *cpc = this_cpu_ptr(epc->pmu->cpu_pmu_context);
 
         /*
          * Groups consisting entirely of software events can always go on.
          */
         if (event->group_caps & PERF_EV_CAP_SOFTWARE)
                 return 1;
         /*
          * If an exclusive group is already on, no other hardware
          * events can go on.
          */
         if (cpc->exclusive)
                 return 0;
         /*
          * If this group is exclusive and there are already
          * events on the CPU, it can't go on.
          */
         if (event->attr.exclusive && !list_empty(get_event_list(event)))
                 return 0;
         /*
          * Otherwise, try to add it if all previous groups were able
          * to go on.
          */
         return can_add_hw;
 }
 
 static void add_event_to_ctx(struct perf_event *event,
                                struct perf_event_context *ctx)
 {
         list_add_event(event, ctx);
         perf_group_attach(event);
 }
 
 static void task_ctx_sched_out(struct perf_event_context *ctx,
                                 enum event_type_t event_type)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
 
         if (!cpuctx->task_ctx)
                 return;
 
         if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
                 return;
 
         ctx_sched_out(ctx, event_type);
 }
 
 static void perf_event_sched_in(struct perf_cpu_context *cpuctx,
                                 struct perf_event_context *ctx)
 {
         ctx_sched_in(&cpuctx->ctx, EVENT_PINNED);
         if (ctx)
                  ctx_sched_in(ctx, EVENT_PINNED);
         ctx_sched_in(&cpuctx->ctx, EVENT_FLEXIBLE);
         if (ctx)
                  ctx_sched_in(ctx, EVENT_FLEXIBLE);
 }
 
 /*
  * We want to maintain the following priority of scheduling:
  *  - CPU pinned (EVENT_CPU | EVENT_PINNED)
  *  - task pinned (EVENT_PINNED)
  *  - CPU flexible (EVENT_CPU | EVENT_FLEXIBLE)
  *  - task flexible (EVENT_FLEXIBLE).
  *
  * In order to avoid unscheduling and scheduling back in everything every
  * time an event is added, only do it for the groups of equal priority and
  * below.
  *
  * This can be called after a batch operation on task events, in which case
  * event_type is a bit mask of the types of events involved. For CPU events,
  * event_type is only either EVENT_PINNED or EVENT_FLEXIBLE.
  */
 /*
  * XXX: ctx_resched() reschedule entire perf_event_context while adding new
  * event to the context or enabling existing event in the context. We can
  * probably optimize it by rescheduling only affected pmu_ctx.
  */
 static void ctx_resched(struct perf_cpu_context *cpuctx,
                         struct perf_event_context *task_ctx,
                         enum event_type_t event_type)
 {
         bool cpu_event = !!(event_type & EVENT_CPU);
 
         /*
          * If pinned groups are involved, flexible groups also need to be
          * scheduled out.
          */
         if (event_type & EVENT_PINNED)
                 event_type |= EVENT_FLEXIBLE;
 
         event_type &= EVENT_ALL;
 
         perf_ctx_disable(&cpuctx->ctx, false);
         if (task_ctx) {
                 perf_ctx_disable(task_ctx, false);
                 task_ctx_sched_out(task_ctx, event_type);
         }
 
         /*
          * Decide which cpu ctx groups to schedule out based on the types
          * of events that caused rescheduling:
          *  - EVENT_CPU: schedule out corresponding groups;
          *  - EVENT_PINNED task events: schedule out EVENT_FLEXIBLE groups;
          *  - otherwise, do nothing more.
          */
         if (cpu_event)
                 ctx_sched_out(&cpuctx->ctx, event_type);
         else if (event_type & EVENT_PINNED)
                 ctx_sched_out(&cpuctx->ctx, EVENT_FLEXIBLE);
 
         perf_event_sched_in(cpuctx, task_ctx);
 
         perf_ctx_enable(&cpuctx->ctx, false);
         if (task_ctx)
                 perf_ctx_enable(task_ctx, false);
 }
 
 void perf_pmu_resched(struct pmu *pmu)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_context *task_ctx = cpuctx->task_ctx;
 
         perf_ctx_lock(cpuctx, task_ctx);
         ctx_resched(cpuctx, task_ctx, EVENT_ALL|EVENT_CPU);
         perf_ctx_unlock(cpuctx, task_ctx);
 }
 
 /*
  * Cross CPU call to install and enable a performance event
  *
  * Very similar to remote_function() + event_function() but cannot assume that
  * things like ctx->is_active and cpuctx->task_ctx are set.
  */
 static int  __perf_install_in_context(void *info)
 {
         struct perf_event *event = info;
         struct perf_event_context *ctx = event->ctx;
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_context *task_ctx = cpuctx->task_ctx;
         bool reprogram = true;
         int ret = 0;
 
         raw_spin_lock(&cpuctx->ctx.lock);
         if (ctx->task) {
                 raw_spin_lock(&ctx->lock);
                 task_ctx = ctx;
 
                 reprogram = (ctx->task == current);
 
                 /*
                  * If the task is running, it must be running on this CPU,
                  * otherwise we cannot reprogram things.
                  *
                  * If its not running, we don't care, ctx->lock will
                  * serialize against it becoming runnable.
                  */
                 if (task_curr(ctx->task) && !reprogram) {
                         ret = -ESRCH;
                         goto unlock;
                 }
 
                 WARN_ON_ONCE(reprogram && cpuctx->task_ctx && cpuctx->task_ctx != ctx);
         } else if (task_ctx) {
                 raw_spin_lock(&task_ctx->lock);
         }
 
 #ifdef CONFIG_CGROUP_PERF
         if (event->state > PERF_EVENT_STATE_OFF && is_cgroup_event(event)) {
                 /*
                  * If the current cgroup doesn't match the event's
                  * cgroup, we should not try to schedule it.
                  */
                 struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx);
                 reprogram = cgroup_is_descendant(cgrp->css.cgroup,
                                         event->cgrp->css.cgroup);
         }
 #endif
 
         if (reprogram) {
                 ctx_sched_out(ctx, EVENT_TIME);
                 add_event_to_ctx(event, ctx);
                 ctx_resched(cpuctx, task_ctx, get_event_type(event));
         } else {
                 add_event_to_ctx(event, ctx);
         }
 
 unlock:
         perf_ctx_unlock(cpuctx, task_ctx);
 
         return ret;
 }
 
 static bool exclusive_event_installable(struct perf_event *event,
                                         struct perf_event_context *ctx);
 
 /*
  * Attach a performance event to a context.
  *
  * Very similar to event_function_call, see comment there.
  */
 static void
 perf_install_in_context(struct perf_event_context *ctx,
                         struct perf_event *event,
                         int cpu)
 {
         struct task_struct *task = READ_ONCE(ctx->task);
 
         lockdep_assert_held(&ctx->mutex);
 
         WARN_ON_ONCE(!exclusive_event_installable(event, ctx));
 
         if (event->cpu != -1)
                 WARN_ON_ONCE(event->cpu != cpu);
 
         /*
          * Ensures that if we can observe event->ctx, both the event and ctx
          * will be 'complete'. See perf_iterate_sb_cpu().
          */
         smp_store_release(&event->ctx, ctx);
 
         /*
          * perf_event_attr::disabled events will not run and can be initialized
          * without IPI. Except when this is the first event for the context, in
          * that case we need the magic of the IPI to set ctx->is_active.
          *
          * The IOC_ENABLE that is sure to follow the creation of a disabled
          * event will issue the IPI and reprogram the hardware.
          */
         if (__perf_effective_state(event) == PERF_EVENT_STATE_OFF &&
             ctx->nr_events && !is_cgroup_event(event)) {
                 raw_spin_lock_irq(&ctx->lock);
                 if (ctx->task == TASK_TOMBSTONE) {
                         raw_spin_unlock_irq(&ctx->lock);
                         return;
                 }
                 add_event_to_ctx(event, ctx);
                 raw_spin_unlock_irq(&ctx->lock);
                 return;
         }
 
         if (!task) {
                 cpu_function_call(cpu, __perf_install_in_context, event);
                 return;
         }
 
         /*
          * Should not happen, we validate the ctx is still alive before calling.
          */
         if (WARN_ON_ONCE(task == TASK_TOMBSTONE))
                 return;
 
         /*
          * Installing events is tricky because we cannot rely on ctx->is_active
          * to be set in case this is the nr_events 0 -> 1 transition.
          *
          * Instead we use task_curr(), which tells us if the task is running.
          * However, since we use task_curr() outside of rq::lock, we can race
          * against the actual state. This means the result can be wrong.
          *
          * If we get a false positive, we retry, this is harmless.
          *
          * If we get a false negative, things are complicated. If we are after
          * perf_event_context_sched_in() ctx::lock will serialize us, and the
          * value must be correct. If we're before, it doesn't matter since
          * perf_event_context_sched_in() will program the counter.
          *
          * However, this hinges on the remote context switch having observed
          * our task->perf_event_ctxp[] store, such that it will in fact take
          * ctx::lock in perf_event_context_sched_in().
          *
          * We do this by task_function_call(), if the IPI fails to hit the task
          * we know any future context switch of task must see the
          * perf_event_ctpx[] store.
          */
 
         /*
          * This smp_mb() orders the task->perf_event_ctxp[] store with the
          * task_cpu() load, such that if the IPI then does not find the task
          * running, a future context switch of that task must observe the
          * store.
          */
         smp_mb();
 again:
         if (!task_function_call(task, __perf_install_in_context, event))
                 return;
 
         raw_spin_lock_irq(&ctx->lock);
         task = ctx->task;
         if (WARN_ON_ONCE(task == TASK_TOMBSTONE)) {
                 /*
                  * Cannot happen because we already checked above (which also
                  * cannot happen), and we hold ctx->mutex, which serializes us
                  * against perf_event_exit_task_context().
                  */
                 raw_spin_unlock_irq(&ctx->lock);
                 return;
         }
         /*
          * If the task is not running, ctx->lock will avoid it becoming so,
          * thus we can safely install the event.
          */
         if (task_curr(task)) {
                 raw_spin_unlock_irq(&ctx->lock);
                 goto again;
         }
         add_event_to_ctx(event, ctx);
         raw_spin_unlock_irq(&ctx->lock);
 }
 
 /*
  * Cross CPU call to enable a performance event
  */
 static void __perf_event_enable(struct perf_event *event,
                                 struct perf_cpu_context *cpuctx,
                                 struct perf_event_context *ctx,
                                 void *info)
 {
         struct perf_event *leader = event->group_leader;
         struct perf_event_context *task_ctx;
 
         if (event->state >= PERF_EVENT_STATE_INACTIVE ||
             event->state <= PERF_EVENT_STATE_ERROR)
                 return;
 
         if (ctx->is_active)
                 ctx_sched_out(ctx, EVENT_TIME);
 
         perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
         perf_cgroup_event_enable(event, ctx);
 
         if (!ctx->is_active)
                 return;
 
         if (!event_filter_match(event)) {
                 ctx_sched_in(ctx, EVENT_TIME);
                 return;
         }
 
         /*
          * If the event is in a group and isn't the group leader,
          * then don't put it on unless the group is on.
          */
         if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE) {
                 ctx_sched_in(ctx, EVENT_TIME);
                 return;
         }
 
         task_ctx = cpuctx->task_ctx;
         if (ctx->task)
                 WARN_ON_ONCE(task_ctx != ctx);
 
         ctx_resched(cpuctx, task_ctx, get_event_type(event));
 }
 
 /*
  * Enable an event.
  *
  * If event->ctx is a cloned context, callers must make sure that
  * every task struct that event->ctx->task could possibly point to
  * remains valid.  This condition is satisfied when called through
  * perf_event_for_each_child or perf_event_for_each as described
  * for perf_event_disable.
  */
 static void _perf_event_enable(struct perf_event *event)
 {
         struct perf_event_context *ctx = event->ctx;
 
         raw_spin_lock_irq(&ctx->lock);
         if (event->state >= PERF_EVENT_STATE_INACTIVE ||
             event->state <  PERF_EVENT_STATE_ERROR) {
 out:
                 raw_spin_unlock_irq(&ctx->lock);
                 return;
         }
 
         /*
          * If the event is in error state, clear that first.
          *
          * That way, if we see the event in error state below, we know that it
          * has gone back into error state, as distinct from the task having
          * been scheduled away before the cross-call arrived.
          */
         if (event->state == PERF_EVENT_STATE_ERROR) {
                 /*
                  * Detached SIBLING events cannot leave ERROR state.
                  */
                 if (event->event_caps & PERF_EV_CAP_SIBLING &&
                     event->group_leader == event)
                         goto out;
 
                 event->state = PERF_EVENT_STATE_OFF;
         }
         raw_spin_unlock_irq(&ctx->lock);
 
         event_function_call(event, __perf_event_enable, NULL);
 }
 
 /*
  * See perf_event_disable();
  */
 void perf_event_enable(struct perf_event *event)
 {
         struct perf_event_context *ctx;
 
         ctx = perf_event_ctx_lock(event);
         _perf_event_enable(event);
         perf_event_ctx_unlock(event, ctx);
 }
 EXPORT_SYMBOL_GPL(perf_event_enable);
 
 struct stop_event_data {
         struct perf_event       *event;
         unsigned int            restart;
 };
 
 static int __perf_event_stop(void *info)
 {
         struct stop_event_data *sd = info;
         struct perf_event *event = sd->event;
 
         /* if it's already INACTIVE, do nothing */
         if (READ_ONCE(event->state) != PERF_EVENT_STATE_ACTIVE)
                 return 0;
 
         /* matches smp_wmb() in event_sched_in() */
         smp_rmb();
 
         /*
          * There is a window with interrupts enabled before we get here,
          * so we need to check again lest we try to stop another CPU's event.
          */
         if (READ_ONCE(event->oncpu) != smp_processor_id())
                 return -EAGAIN;
 
         event->pmu->stop(event, PERF_EF_UPDATE);
 
         /*
          * May race with the actual stop (through perf_pmu_output_stop()),
          * but it is only used for events with AUX ring buffer, and such
          * events will refuse to restart because of rb::aux_mmap_count==0,
          * see comments in perf_aux_output_begin().
          *
          * Since this is happening on an event-local CPU, no trace is lost
          * while restarting.
          */
         if (sd->restart)
                 event->pmu->start(event, 0);
 
         return 0;
 }
 
 static int perf_event_stop(struct perf_event *event, int restart)
 {
         struct stop_event_data sd = {
                 .event          = event,
                 .restart        = restart,
         };
         int ret = 0;
 
         do {
                 if (READ_ONCE(event->state) != PERF_EVENT_STATE_ACTIVE)
                         return 0;
 
                 /* matches smp_wmb() in event_sched_in() */
                 smp_rmb();
 
                 /*
                  * We only want to restart ACTIVE events, so if the event goes
                  * inactive here (event->oncpu==-1), there's nothing more to do;
                  * fall through with ret==-ENXIO.
                  */
                 ret = cpu_function_call(READ_ONCE(event->oncpu),
                                         __perf_event_stop, &sd);
         } while (ret == -EAGAIN);
 
         return ret;
 }
 
 /*
  * In order to contain the amount of racy and tricky in the address filter
  * configuration management, it is a two part process:
  *
  * (p1) when userspace mappings change as a result of (1) or (2) or (3) below,
  *      we update the addresses of corresponding vmas in
  *      event::addr_filter_ranges array and bump the event::addr_filters_gen;
  * (p2) when an event is scheduled in (pmu::add), it calls
  *      perf_event_addr_filters_sync() which calls pmu::addr_filters_sync()
  *      if the generation has changed since the previous call.
  *
  * If (p1) happens while the event is active, we restart it to force (p2).
  *
  * (1) perf_addr_filters_apply(): adjusting filters' offsets based on
  *     pre-existing mappings, called once when new filters arrive via SET_FILTER
  *     ioctl;
  * (2) perf_addr_filters_adjust(): adjusting filters' offsets based on newly
  *     registered mapping, called for every new mmap(), with mm::mmap_lock down
  *     for reading;
  * (3) perf_event_addr_filters_exec(): clearing filters' offsets in the process
  *     of exec.
  */
 void perf_event_addr_filters_sync(struct perf_event *event)
 {
         struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
 
         if (!has_addr_filter(event))
                 return;
 
         raw_spin_lock(&ifh->lock);
         if (event->addr_filters_gen != event->hw.addr_filters_gen) {
                 event->pmu->addr_filters_sync(event);
                 event->hw.addr_filters_gen = event->addr_filters_gen;
         }
         raw_spin_unlock(&ifh->lock);
 }
 EXPORT_SYMBOL_GPL(perf_event_addr_filters_sync);
 
 static int _perf_event_refresh(struct perf_event *event, int refresh)
 {
         /*
          * not supported on inherited events
          */
         if (event->attr.inherit || !is_sampling_event(event))
                 return -EINVAL;
 
         atomic_add(refresh, &event->event_limit);
         _perf_event_enable(event);
 
         return 0;
 }
 
 /*
  * See perf_event_disable()
  */
 int perf_event_refresh(struct perf_event *event, int refresh)
 {
         struct perf_event_context *ctx;
         int ret;
 
         ctx = perf_event_ctx_lock(event);
         ret = _perf_event_refresh(event, refresh);
         perf_event_ctx_unlock(event, ctx);
 
         return ret;
 }
 EXPORT_SYMBOL_GPL(perf_event_refresh);
 
 static int perf_event_modify_breakpoint(struct perf_event *bp,
                                          struct perf_event_attr *attr)
 {
         int err;
 
         _perf_event_disable(bp);
 
         err = modify_user_hw_breakpoint_check(bp, attr, true);
 
         if (!bp->attr.disabled)
                 _perf_event_enable(bp);
 
         return err;
 }
 
 /*
  * Copy event-type-independent attributes that may be modified.
  */
 static void perf_event_modify_copy_attr(struct perf_event_attr *to,
                                         const struct perf_event_attr *from)
 {
         to->sig_data = from->sig_data;
 }
 
 static int perf_event_modify_attr(struct perf_event *event,
                                   struct perf_event_attr *attr)
 {
         int (*func)(struct perf_event *, struct perf_event_attr *);
         struct perf_event *child;
         int err;
 
         if (event->attr.type != attr->type)
                 return -EINVAL;
 
         switch (event->attr.type) {
         case PERF_TYPE_BREAKPOINT:
                 func = perf_event_modify_breakpoint;
                 break;
         default:
                 /* Place holder for future additions. */
                 return -EOPNOTSUPP;
         }
 
         WARN_ON_ONCE(event->ctx->parent_ctx);
 
         mutex_lock(&event->child_mutex);
         /*
          * Event-type-independent attributes must be copied before event-type
          * modification, which will validate that final attributes match the
          * source attributes after all relevant attributes have been copied.
          */
         perf_event_modify_copy_attr(&event->attr, attr);
         err = func(event, attr);
         if (err)
                 goto out;
         list_for_each_entry(child, &event->child_list, child_list) {
                 perf_event_modify_copy_attr(&child->attr, attr);
                 err = func(child, attr);
                 if (err)
                         goto out;
         }
 out:
         mutex_unlock(&event->child_mutex);
         return err;
 }
 
 static void __pmu_ctx_sched_out(struct perf_event_pmu_context *pmu_ctx,
                                 enum event_type_t event_type)
 {
         struct perf_event_context *ctx = pmu_ctx->ctx;
         struct perf_event *event, *tmp;
         struct pmu *pmu = pmu_ctx->pmu;
 
         if (ctx->task && !ctx->is_active) {
                 struct perf_cpu_pmu_context *cpc;
 
                 cpc = this_cpu_ptr(pmu->cpu_pmu_context);
                 WARN_ON_ONCE(cpc->task_epc && cpc->task_epc != pmu_ctx);
                 cpc->task_epc = NULL;
         }
 
         if (!event_type)
                 return;
 
         perf_pmu_disable(pmu);
         if (event_type & EVENT_PINNED) {
                 list_for_each_entry_safe(event, tmp,
                                          &pmu_ctx->pinned_active,
                                          active_list)
                         group_sched_out(event, ctx);
         }
 
         if (event_type & EVENT_FLEXIBLE) {
                 list_for_each_entry_safe(event, tmp,
                                          &pmu_ctx->flexible_active,
                                          active_list)
                         group_sched_out(event, ctx);
                 /*
                  * Since we cleared EVENT_FLEXIBLE, also clear
                  * rotate_necessary, is will be reset by
                  * ctx_flexible_sched_in() when needed.
                  */
                 pmu_ctx->rotate_necessary = 0;
         }
         perf_pmu_enable(pmu);
 }
 
 static void
 ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_pmu_context *pmu_ctx;
         int is_active = ctx->is_active;
         bool cgroup = event_type & EVENT_CGROUP;
 
         event_type &= ~EVENT_CGROUP;
 
         lockdep_assert_held(&ctx->lock);
 
         if (likely(!ctx->nr_events)) {
                 /*
                  * See __perf_remove_from_context().
                  */
                 WARN_ON_ONCE(ctx->is_active);
                 if (ctx->task)
                         WARN_ON_ONCE(cpuctx->task_ctx);
                 return;
         }
 
         /*
          * Always update time if it was set; not only when it changes.
          * Otherwise we can 'forget' to update time for any but the last
          * context we sched out. For example:
          *
          *   ctx_sched_out(.event_type = EVENT_FLEXIBLE)
          *   ctx_sched_out(.event_type = EVENT_PINNED)
          *
          * would only update time for the pinned events.
          */
         if (is_active & EVENT_TIME) {
                 /* update (and stop) ctx time */
                 update_context_time(ctx);
                 update_cgrp_time_from_cpuctx(cpuctx, ctx == &cpuctx->ctx);
                 /*
                  * CPU-release for the below ->is_active store,
                  * see __load_acquire() in perf_event_time_now()
                  */
                 barrier();
         }
 
         ctx->is_active &= ~event_type;
         if (!(ctx->is_active & EVENT_ALL))
                 ctx->is_active = 0;
 
         if (ctx->task) {
                 WARN_ON_ONCE(cpuctx->task_ctx != ctx);
                 if (!ctx->is_active)
                         cpuctx->task_ctx = NULL;
         }
 
         is_active ^= ctx->is_active; /* changed bits */
 
         list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
                 if (cgroup && !pmu_ctx->nr_cgroups)
                         continue;
                 __pmu_ctx_sched_out(pmu_ctx, is_active);
         }
 }
 
 /*
  * Test whether two contexts are equivalent, i.e. whether they have both been
  * cloned from the same version of the same context.
  *
  * Equivalence is measured using a generation number in the context that is
  * incremented on each modification to it; see unclone_ctx(), list_add_event()
  * and list_del_event().
  */
 static int context_equiv(struct perf_event_context *ctx1,
                          struct perf_event_context *ctx2)
 {
         lockdep_assert_held(&ctx1->lock);
         lockdep_assert_held(&ctx2->lock);
 
         /* Pinning disables the swap optimization */
         if (ctx1->pin_count || ctx2->pin_count)
                 return 0;
 
         /* If ctx1 is the parent of ctx2 */
         if (ctx1 == ctx2->parent_ctx && ctx1->generation == ctx2->parent_gen)
                 return 1;
 
         /* If ctx2 is the parent of ctx1 */
         if (ctx1->parent_ctx == ctx2 && ctx1->parent_gen == ctx2->generation)
                 return 1;
 
         /*
          * If ctx1 and ctx2 have the same parent; we flatten the parent
          * hierarchy, see perf_event_init_context().
          */
         if (ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx &&
                         ctx1->parent_gen == ctx2->parent_gen)
                 return 1;
 
         /* Unmatched */
         return 0;
 }
 
 static void __perf_event_sync_stat(struct perf_event *event,
                                      struct perf_event *next_event)
 {
         u64 value;
 
         if (!event->attr.inherit_stat)
                 return;
 
         /*
          * Update the event value, we cannot use perf_event_read()
          * because we're in the middle of a context switch and have IRQs
          * disabled, which upsets smp_call_function_single(), however
          * we know the event must be on the current CPU, therefore we
          * don't need to use it.
          */
         if (event->state == PERF_EVENT_STATE_ACTIVE)
                 event->pmu->read(event);
 
         perf_event_update_time(event);
 
         /*
          * In order to keep per-task stats reliable we need to flip the event
          * values when we flip the contexts.
          */
         value = local64_read(&next_event->count);
         value = local64_xchg(&event->count, value);
         local64_set(&next_event->count, value);
 
         swap(event->total_time_enabled, next_event->total_time_enabled);
         swap(event->total_time_running, next_event->total_time_running);
 
         /*
          * Since we swizzled the values, update the user visible data too.
          */
         perf_event_update_userpage(event);
         perf_event_update_userpage(next_event);
 }
 
 static void perf_event_sync_stat(struct perf_event_context *ctx,
                                    struct perf_event_context *next_ctx)
 {
         struct perf_event *event, *next_event;
 
         if (!ctx->nr_stat)
                 return;
 
         update_context_time(ctx);
 
         event = list_first_entry(&ctx->event_list,
                                    struct perf_event, event_entry);
 
         next_event = list_first_entry(&next_ctx->event_list,
                                         struct perf_event, event_entry);
 
         while (&event->event_entry != &ctx->event_list &&
                &next_event->event_entry != &next_ctx->event_list) {
 
                 __perf_event_sync_stat(event, next_event);
 
                 event = list_next_entry(event, event_entry);
                 next_event = list_next_entry(next_event, event_entry);
         }
 }
 
 #define double_list_for_each_entry(pos1, pos2, head1, head2, member)    \
         for (pos1 = list_first_entry(head1, typeof(*pos1), member),     \
              pos2 = list_first_entry(head2, typeof(*pos2), member);     \
              !list_entry_is_head(pos1, head1, member) &&                \
              !list_entry_is_head(pos2, head2, member);                  \
              pos1 = list_next_entry(pos1, member),                      \
              pos2 = list_next_entry(pos2, member))
 
 static void perf_event_swap_task_ctx_data(struct perf_event_context *prev_ctx,
                                           struct perf_event_context *next_ctx)
 {
         struct perf_event_pmu_context *prev_epc, *next_epc;
 
         if (!prev_ctx->nr_task_data)
                 return;
 
         double_list_for_each_entry(prev_epc, next_epc,
                                    &prev_ctx->pmu_ctx_list, &next_ctx->pmu_ctx_list,
                                    pmu_ctx_entry) {
 
                 if (WARN_ON_ONCE(prev_epc->pmu != next_epc->pmu))
                         continue;
 
                 /*
                  * PMU specific parts of task perf context can require
                  * additional synchronization. As an example of such
                  * synchronization see implementation details of Intel
                  * LBR call stack data profiling;
                  */
                 if (prev_epc->pmu->swap_task_ctx)
                         prev_epc->pmu->swap_task_ctx(prev_epc, next_epc);
                 else
                         swap(prev_epc->task_ctx_data, next_epc->task_ctx_data);
         }
 }
 
 static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, bool sched_in)
 {
         struct perf_event_pmu_context *pmu_ctx;
         struct perf_cpu_pmu_context *cpc;
 
         list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
                 cpc = this_cpu_ptr(pmu_ctx->pmu->cpu_pmu_context);
 
                 if (cpc->sched_cb_usage && pmu_ctx->pmu->sched_task)
                         pmu_ctx->pmu->sched_task(pmu_ctx, sched_in);
         }
 }
 
 static void
 perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
 {
         struct perf_event_context *ctx = task->perf_event_ctxp;
         struct perf_event_context *next_ctx;
         struct perf_event_context *parent, *next_parent;
         int do_switch = 1;
 
         if (likely(!ctx))
                 return;
 
         rcu_read_lock();
         next_ctx = rcu_dereference(next->perf_event_ctxp);
         if (!next_ctx)
                 goto unlock;
 
         parent = rcu_dereference(ctx->parent_ctx);
         next_parent = rcu_dereference(next_ctx->parent_ctx);
 
         /* If neither context have a parent context; they cannot be clones. */
         if (!parent && !next_parent)
                 goto unlock;
 
         if (next_parent == ctx || next_ctx == parent || next_parent == parent) {
                 /*
                  * Looks like the two contexts are clones, so we might be
                  * able to optimize the context switch.  We lock both
                  * contexts and check that they are clones under the
                  * lock (including re-checking that neither has been
                  * uncloned in the meantime).  It doesn't matter which
                  * order we take the locks because no other cpu could
                  * be trying to lock both of these tasks.
                  */
                 raw_spin_lock(&ctx->lock);
                 raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING);
                 if (context_equiv(ctx, next_ctx)) {
 
                         perf_ctx_disable(ctx, false);
 
                         /* PMIs are disabled; ctx->nr_pending is stable. */
                         if (local_read(&ctx->nr_pending) ||
                             local_read(&next_ctx->nr_pending)) {
                                 /*
                                  * Must not swap out ctx when there's pending
                                  * events that rely on the ctx->task relation.
                                  */
                                 raw_spin_unlock(&next_ctx->lock);
                                 rcu_read_unlock();
                                 goto inside_switch;
                         }
 
                         WRITE_ONCE(ctx->task, next);
                         WRITE_ONCE(next_ctx->task, task);
 
                         perf_ctx_sched_task_cb(ctx, false);
                         perf_event_swap_task_ctx_data(ctx, next_ctx);
 
                         perf_ctx_enable(ctx, false);
 
                         /*
                          * RCU_INIT_POINTER here is safe because we've not
                          * modified the ctx and the above modification of
                          * ctx->task and ctx->task_ctx_data are immaterial
                          * since those values are always verified under
                          * ctx->lock which we're now holding.
                          */
                         RCU_INIT_POINTER(task->perf_event_ctxp, next_ctx);
                         RCU_INIT_POINTER(next->perf_event_ctxp, ctx);
 
                         do_switch = 0;
 
                         perf_event_sync_stat(ctx, next_ctx);
                 }
                 raw_spin_unlock(&next_ctx->lock);
                 raw_spin_unlock(&ctx->lock);
         }
 unlock:
         rcu_read_unlock();
 
         if (do_switch) {
                 raw_spin_lock(&ctx->lock);
                 perf_ctx_disable(ctx, false);
 
 inside_switch:
                 perf_ctx_sched_task_cb(ctx, false);
                 task_ctx_sched_out(ctx, EVENT_ALL);
 
                 perf_ctx_enable(ctx, false);
                 raw_spin_unlock(&ctx->lock);
         }
 }
 
 static DEFINE_PER_CPU(struct list_head, sched_cb_list);
 static DEFINE_PER_CPU(int, perf_sched_cb_usages);
 
 void perf_sched_cb_dec(struct pmu *pmu)
 {
         struct perf_cpu_pmu_context *cpc = this_cpu_ptr(pmu->cpu_pmu_context);
 
         this_cpu_dec(perf_sched_cb_usages);
         barrier();
 
         if (!--cpc->sched_cb_usage)
                 list_del(&cpc->sched_cb_entry);
 }
 
 
 void perf_sched_cb_inc(struct pmu *pmu)
 {
         struct perf_cpu_pmu_context *cpc = this_cpu_ptr(pmu->cpu_pmu_context);
 
         if (!cpc->sched_cb_usage++)
                 list_add(&cpc->sched_cb_entry, this_cpu_ptr(&sched_cb_list));
 
         barrier();
         this_cpu_inc(perf_sched_cb_usages);
 }
 
 /*
  * This function provides the context switch callback to the lower code
  * layer. It is invoked ONLY when the context switch callback is enabled.
  *
  * This callback is relevant even to per-cpu events; for example multi event
  * PEBS requires this to provide PID/TID information. This requires we flush
  * all queued PEBS records before we context switch to a new task.
  */
 static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, bool sched_in)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct pmu *pmu;
 
         pmu = cpc->epc.pmu;
 
         /* software PMUs will not have sched_task */
         if (WARN_ON_ONCE(!pmu->sched_task))
                 return;
 
         perf_ctx_lock(cpuctx, cpuctx->task_ctx);
         perf_pmu_disable(pmu);
 
         pmu->sched_task(cpc->task_epc, sched_in);
 
         perf_pmu_enable(pmu);
         perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
 }
 
 static void perf_pmu_sched_task(struct task_struct *prev,
                                 struct task_struct *next,
                                 bool sched_in)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_cpu_pmu_context *cpc;
 
         /* cpuctx->task_ctx will be handled in perf_event_context_sched_in/out */
         if (prev == next || cpuctx->task_ctx)
                 return;
 
         list_for_each_entry(cpc, this_cpu_ptr(&sched_cb_list), sched_cb_entry)
                 __perf_pmu_sched_task(cpc, sched_in);
 }
 
 static void perf_event_switch(struct task_struct *task,
                               struct task_struct *next_prev, bool sched_in);
 
 /*
  * Called from scheduler to remove the events of the current task,
  * with interrupts disabled.
  *
  * We stop each event and update the event value in event->count.
  *
  * This does not protect us against NMI, but disable()
  * sets the disabled bit in the control field of event _before_
  * accessing the event control register. If a NMI hits, then it will
  * not restart the event.
  */
 void __perf_event_task_sched_out(struct task_struct *task,
                                  struct task_struct *next)
 {
         if (__this_cpu_read(perf_sched_cb_usages))
                 perf_pmu_sched_task(task, next, false);
 
         if (atomic_read(&nr_switch_events))
                 perf_event_switch(task, next, false);
 
         perf_event_context_sched_out(task, next);
 
         /*
          * if cgroup events exist on this CPU, then we need
          * to check if we have to switch out PMU state.
          * cgroup event are system-wide mode only
          */
         perf_cgroup_switch(next);
 }
 
 static bool perf_less_group_idx(const void *l, const void *r, void __always_unused *args)
 {
         const struct perf_event *le = *(const struct perf_event **)l;
         const struct perf_event *re = *(const struct perf_event **)r;
 
         return le->group_index < re->group_index;
 }
 
 static void swap_ptr(void *l, void *r, void __always_unused *args)
 {
         void **lp = l, **rp = r;
 
         swap(*lp, *rp);
 }
 
 DEFINE_MIN_HEAP(struct perf_event *, perf_event_min_heap);
 
 static const struct min_heap_callbacks perf_min_heap = {
         .less = perf_less_group_idx,
         .swp = swap_ptr,
 };
 
 static void __heap_add(struct perf_event_min_heap *heap, struct perf_event *event)
 {
         struct perf_event **itrs = heap->data;
 
         if (event) {
                 itrs[heap->nr] = event;
                 heap->nr++;
         }
 }
 
 static void __link_epc(struct perf_event_pmu_context *pmu_ctx)
 {
         struct perf_cpu_pmu_context *cpc;
 
         if (!pmu_ctx->ctx->task)
                 return;
 
         cpc = this_cpu_ptr(pmu_ctx->pmu->cpu_pmu_context);
         WARN_ON_ONCE(cpc->task_epc && cpc->task_epc != pmu_ctx);
         cpc->task_epc = pmu_ctx;
 }
 
 static noinline int visit_groups_merge(struct perf_event_context *ctx,
                                 struct perf_event_groups *groups, int cpu,
                                 struct pmu *pmu,
                                 int (*func)(struct perf_event *, void *),
                                 void *data)
 {
 #ifdef CONFIG_CGROUP_PERF
         struct cgroup_subsys_state *css = NULL;
 #endif
         struct perf_cpu_context *cpuctx = NULL;
         /* Space for per CPU and/or any CPU event iterators. */
         struct perf_event *itrs[2];
         struct perf_event_min_heap event_heap;
         struct perf_event **evt;
         int ret;
 
         if (pmu->filter && pmu->filter(pmu, cpu))
                 return 0;
 
         if (!ctx->task) {
                 cpuctx = this_cpu_ptr(&perf_cpu_context);
                 event_heap = (struct perf_event_min_heap){
                         .data = cpuctx->heap,
                         .nr = 0,
                         .size = cpuctx->heap_size,
                 };
 
                 lockdep_assert_held(&cpuctx->ctx.lock);
 
 #ifdef CONFIG_CGROUP_PERF
                 if (cpuctx->cgrp)
                         css = &cpuctx->cgrp->css;
 #endif
         } else {
                 event_heap = (struct perf_event_min_heap){
                         .data = itrs,
                         .nr = 0,
                         .size = ARRAY_SIZE(itrs),
                 };
                 /* Events not within a CPU context may be on any CPU. */
                 __heap_add(&event_heap, perf_event_groups_first(groups, -1, pmu, NULL));
         }
         evt = event_heap.data;
 
         __heap_add(&event_heap, perf_event_groups_first(groups, cpu, pmu, NULL));
 
 #ifdef CONFIG_CGROUP_PERF
         for (; css; css = css->parent)
                 __heap_add(&event_heap, perf_event_groups_first(groups, cpu, pmu, css->cgroup));
 #endif
 
         if (event_heap.nr) {
                 __link_epc((*evt)->pmu_ctx);
                 perf_assert_pmu_disabled((*evt)->pmu_ctx->pmu);
         }
 
         min_heapify_all(&event_heap, &perf_min_heap, NULL);
 
         while (event_heap.nr) {
                 ret = func(*evt, data);
                 if (ret)
                         return ret;
 
                 *evt = perf_event_groups_next(*evt, pmu);
                 if (*evt)
                         min_heap_sift_down(&event_heap, 0, &perf_min_heap, NULL);
                 else
                         min_heap_pop(&event_heap, &perf_min_heap, NULL);
         }
 
         return 0;
 }
 
 /*
  * Because the userpage is strictly per-event (there is no concept of context,
  * so there cannot be a context indirection), every userpage must be updated
  * when context time starts :-(
  *
  * IOW, we must not miss EVENT_TIME edges.
  */
 static inline bool event_update_userpage(struct perf_event *event)
 {
         if (likely(!atomic_read(&event->mmap_count)))
                 return false;
 
         perf_event_update_time(event);
         perf_event_update_userpage(event);
 
         return true;
 }
 
 static inline void group_update_userpage(struct perf_event *group_event)
 {
         struct perf_event *event;
 
         if (!event_update_userpage(group_event))
                 return;
 
         for_each_sibling_event(event, group_event)
                 event_update_userpage(event);
 }
 
 static int merge_sched_in(struct perf_event *event, void *data)
 {
         struct perf_event_context *ctx = event->ctx;
         int *can_add_hw = data;
 
         if (event->state <= PERF_EVENT_STATE_OFF)
                 return 0;
 
         if (!event_filter_match(event))
                 return 0;
 
         if (group_can_go_on(event, *can_add_hw)) {
                 if (!group_sched_in(event, ctx))
                         list_add_tail(&event->active_list, get_event_list(event));
         }
 
         if (event->state == PERF_EVENT_STATE_INACTIVE) {
                 *can_add_hw = 0;
                 if (event->attr.pinned) {
                         perf_cgroup_event_disable(event, ctx);
                         perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
                 } else {
                         struct perf_cpu_pmu_context *cpc;
 
                         event->pmu_ctx->rotate_necessary = 1;
                         cpc = this_cpu_ptr(event->pmu_ctx->pmu->cpu_pmu_context);
                         perf_mux_hrtimer_restart(cpc);
                         group_update_userpage(event);
                 }
         }
 
         return 0;
 }
 
 static void pmu_groups_sched_in(struct perf_event_context *ctx,
                                 struct perf_event_groups *groups,
                                 struct pmu *pmu)
 {
         int can_add_hw = 1;
         visit_groups_merge(ctx, groups, smp_processor_id(), pmu,
                            merge_sched_in, &can_add_hw);
 }
 
 static void ctx_groups_sched_in(struct perf_event_context *ctx,
                                 struct perf_event_groups *groups,
                                 bool cgroup)
 {
         struct perf_event_pmu_context *pmu_ctx;
 
         list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
                 if (cgroup && !pmu_ctx->nr_cgroups)
                         continue;
                 pmu_groups_sched_in(ctx, groups, pmu_ctx->pmu);
         }
 }
 
 static void __pmu_ctx_sched_in(struct perf_event_context *ctx,
                                struct pmu *pmu)
 {
         pmu_groups_sched_in(ctx, &ctx->flexible_groups, pmu);
 }
 
 static void
 ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         int is_active = ctx->is_active;
         bool cgroup = event_type & EVENT_CGROUP;
 
         event_type &= ~EVENT_CGROUP;
 
         lockdep_assert_held(&ctx->lock);
 
         if (likely(!ctx->nr_events))
                 return;
 
         if (!(is_active & EVENT_TIME)) {
                 /* start ctx time */
                 __update_context_time(ctx, false);
                 perf_cgroup_set_timestamp(cpuctx);
                 /*
                  * CPU-release for the below ->is_active store,
                  * see __load_acquire() in perf_event_time_now()
                  */
                 barrier();
         }
 
         ctx->is_active |= (event_type | EVENT_TIME);
         if (ctx->task) {
                 if (!is_active)
                         cpuctx->task_ctx = ctx;
                 else
                         WARN_ON_ONCE(cpuctx->task_ctx != ctx);
         }
 
         is_active ^= ctx->is_active; /* changed bits */
 
         /*
          * First go through the list and put on any pinned groups
          * in order to give them the best chance of going on.
          */
         if (is_active & EVENT_PINNED)
                 ctx_groups_sched_in(ctx, &ctx->pinned_groups, cgroup);
 
         /* Then walk through the lower prio flexible groups */
         if (is_active & EVENT_FLEXIBLE)
                 ctx_groups_sched_in(ctx, &ctx->flexible_groups, cgroup);
 }
 
 static void perf_event_context_sched_in(struct task_struct *task)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_context *ctx;
 
         rcu_read_lock();
         ctx = rcu_dereference(task->perf_event_ctxp);
         if (!ctx)
                 goto rcu_unlock;
 
         if (cpuctx->task_ctx == ctx) {
                 perf_ctx_lock(cpuctx, ctx);
                 perf_ctx_disable(ctx, false);
 
                 perf_ctx_sched_task_cb(ctx, true);
 
                 perf_ctx_enable(ctx, false);
                 perf_ctx_unlock(cpuctx, ctx);
                 goto rcu_unlock;
         }
 
         perf_ctx_lock(cpuctx, ctx);
         /*
          * We must check ctx->nr_events while holding ctx->lock, such
          * that we serialize against perf_install_in_context().
          */
         if (!ctx->nr_events)
                 goto unlock;
 
         perf_ctx_disable(ctx, false);
         /*
          * We want to keep the following priority order:
          * cpu pinned (that don't need to move), task pinned,
          * cpu flexible, task flexible.
          *
          * However, if task's ctx is not carrying any pinned
          * events, no need to flip the cpuctx's events around.
          */
         if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree)) {
                 perf_ctx_disable(&cpuctx->ctx, false);
                 ctx_sched_out(&cpuctx->ctx, EVENT_FLEXIBLE);
         }
 
         perf_event_sched_in(cpuctx, ctx);
 
         perf_ctx_sched_task_cb(cpuctx->task_ctx, true);
 
         if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
                 perf_ctx_enable(&cpuctx->ctx, false);
 
         perf_ctx_enable(ctx, false);
 
 unlock:
         perf_ctx_unlock(cpuctx, ctx);
 rcu_unlock:
         rcu_read_unlock();
 }
 
 /*
  * Called from scheduler to add the events of the current task
  * with interrupts disabled.
  *
  * We restore the event value and then enable it.
  *
  * This does not protect us against NMI, but enable()
  * sets the enabled bit in the control field of event _before_
  * accessing the event control register. If a NMI hits, then it will
  * keep the event running.
  */
 void __perf_event_task_sched_in(struct task_struct *prev,
                                 struct task_struct *task)
 {
         perf_event_context_sched_in(task);
 
         if (atomic_read(&nr_switch_events))
                 perf_event_switch(task, prev, true);
 
         if (__this_cpu_read(perf_sched_cb_usages))
                 perf_pmu_sched_task(prev, task, true);
 }
 
 static u64 perf_calculate_period(struct perf_event *event, u64 nsec, u64 count)
 {
         u64 frequency = event->attr.sample_freq;
         u64 sec = NSEC_PER_SEC;
         u64 divisor, dividend;
 
         int count_fls, nsec_fls, frequency_fls, sec_fls;
 
         count_fls = fls64(count);
         nsec_fls = fls64(nsec);
         frequency_fls = fls64(frequency);
         sec_fls = 30;
 
         /*
          * We got @count in @nsec, with a target of sample_freq HZ
          * the target period becomes:
          *
          *             @count * 10^9
          * period = -------------------
          *          @nsec * sample_freq
          *
          */
 
         /*
          * Reduce accuracy by one bit such that @a and @b converge
          * to a similar magnitude.
          */
 #define REDUCE_FLS(a, b)                \
 do {                                    \
         if (a##_fls > b##_fls) {        \
                 a >>= 1;                \
                 a##_fls--;              \
         } else {                        \
                 b >>= 1;                \
                 b##_fls--;              \
         }                               \
 } while (0)
 
         /*
          * Reduce accuracy until either term fits in a u64, then proceed with
          * the other, so that finally we can do a u64/u64 division.
          */
         while (count_fls + sec_fls > 64 && nsec_fls + frequency_fls > 64) {
                 REDUCE_FLS(nsec, frequency);
                 REDUCE_FLS(sec, count);
         }
 
         if (count_fls + sec_fls > 64) {
                 divisor = nsec * frequency;
 
                 while (count_fls + sec_fls > 64) {
                         REDUCE_FLS(count, sec);
                         divisor >>= 1;
                 }
 
                 dividend = count * sec;
         } else {
                 dividend = count * sec;
 
                 while (nsec_fls + frequency_fls > 64) {
                         REDUCE_FLS(nsec, frequency);
                         dividend >>= 1;
                 }
 
                 divisor = nsec * frequency;
         }
 
         if (!divisor)
                 return dividend;
 
         return div64_u64(dividend, divisor);
 }
 
 static DEFINE_PER_CPU(int, perf_throttled_count);
 static DEFINE_PER_CPU(u64, perf_throttled_seq);
 
 static void perf_adjust_period(struct perf_event *event, u64 nsec, u64 count, bool disable)
 {
         struct hw_perf_event *hwc = &event->hw;
         s64 period, sample_period;
         s64 delta;
 
         period = perf_calculate_period(event, nsec, count);
 
         delta = (s64)(period - hwc->sample_period);
         if (delta >= 0)
                 delta += 7;
         else
                 delta -= 7;
         delta /= 8; /* low pass filter */
 
         sample_period = hwc->sample_period + delta;
 
         if (!sample_period)
                 sample_period = 1;
 
         hwc->sample_period = sample_period;
 
         if (local64_read(&hwc->period_left) > 8*sample_period) {
                 if (disable)
                         event->pmu->stop(event, PERF_EF_UPDATE);
 
                 local64_set(&hwc->period_left, 0);
 
                 if (disable)
                         event->pmu->start(event, PERF_EF_RELOAD);
         }
 }
 
 static void perf_adjust_freq_unthr_events(struct list_head *event_list)
 {
         struct perf_event *event;
         struct hw_perf_event *hwc;
         u64 now, period = TICK_NSEC;
         s64 delta;
 
         list_for_each_entry(event, event_list, active_list) {
                 if (event->state != PERF_EVENT_STATE_ACTIVE)
                         continue;
 
                 // XXX use visit thingy to avoid the -1,cpu match
                 if (!event_filter_match(event))
                         continue;
 
                 hwc = &event->hw;
 
                 if (hwc->interrupts == MAX_INTERRUPTS) {
                         hwc->interrupts = 0;
                         perf_log_throttle(event, 1);
                         if (!event->attr.freq || !event->attr.sample_freq)
                                 event->pmu->start(event, 0);
                 }
 
                 if (!event->attr.freq || !event->attr.sample_freq)
                         continue;
 
                 /*
                  * stop the event and update event->count
                  */
                 event->pmu->stop(event, PERF_EF_UPDATE);
 
                 now = local64_read(&event->count);
                 delta = now - hwc->freq_count_stamp;
                 hwc->freq_count_stamp = now;
 
                 /*
                  * restart the event
                  * reload only if value has changed
                  * we have stopped the event so tell that
                  * to perf_adjust_period() to avoid stopping it
                  * twice.
                  */
                 if (delta > 0)
                         perf_adjust_period(event, period, delta, false);
 
                 event->pmu->start(event, delta > 0 ? PERF_EF_RELOAD : 0);
         }
 }
 
 /*
  * combine freq adjustment with unthrottling to avoid two passes over the
  * events. At the same time, make sure, having freq events does not change
  * the rate of unthrottling as that would introduce bias.
  */
 static void
 perf_adjust_freq_unthr_context(struct perf_event_context *ctx, bool unthrottle)
 {
         struct perf_event_pmu_context *pmu_ctx;
 
         /*
          * only need to iterate over all events iff:
          * - context have events in frequency mode (needs freq adjust)
          * - there are events to unthrottle on this cpu
          */
         if (!(ctx->nr_freq || unthrottle))
                 return;
 
         raw_spin_lock(&ctx->lock);
 
         list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
                 if (!(pmu_ctx->nr_freq || unthrottle))
                         continue;
                 if (!perf_pmu_ctx_is_active(pmu_ctx))
                         continue;
                 if (pmu_ctx->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT)
                         continue;
 
                 perf_pmu_disable(pmu_ctx->pmu);
                 perf_adjust_freq_unthr_events(&pmu_ctx->pinned_active);
                 perf_adjust_freq_unthr_events(&pmu_ctx->flexible_active);
                 perf_pmu_enable(pmu_ctx->pmu);
         }
 
         raw_spin_unlock(&ctx->lock);
 }
 
 /*
  * Move @event to the tail of the @ctx's elegible events.
  */
 static void rotate_ctx(struct perf_event_context *ctx, struct perf_event *event)
 {
         /*
          * Rotate the first entry last of non-pinned groups. Rotation might be
          * disabled by the inheritance code.
          */
         if (ctx->rotate_disable)
                 return;
 
         perf_event_groups_delete(&ctx->flexible_groups, event);
         perf_event_groups_insert(&ctx->flexible_groups, event);
 }
 
 /* pick an event from the flexible_groups to rotate */
 static inline struct perf_event *
 ctx_event_to_rotate(struct perf_event_pmu_context *pmu_ctx)
 {
         struct perf_event *event;
         struct rb_node *node;
         struct rb_root *tree;
         struct __group_key key = {
                 .pmu = pmu_ctx->pmu,
         };
 
         /* pick the first active flexible event */
         event = list_first_entry_or_null(&pmu_ctx->flexible_active,
                                          struct perf_event, active_list);
         if (event)
                 goto out;
 
         /* if no active flexible event, pick the first event */
         tree = &pmu_ctx->ctx->flexible_groups.tree;
 
         if (!pmu_ctx->ctx->task) {
                 key.cpu = smp_processor_id();
 
                 node = rb_find_first(&key, tree, __group_cmp_ignore_cgroup);
                 if (node)
                         event = __node_2_pe(node);
                 goto out;
         }
 
         key.cpu = -1;
         node = rb_find_first(&key, tree, __group_cmp_ignore_cgroup);
         if (node) {
                 event = __node_2_pe(node);
                 goto out;
         }
 
         key.cpu = smp_processor_id();
         node = rb_find_first(&key, tree, __group_cmp_ignore_cgroup);
         if (node)
                 event = __node_2_pe(node);
 
 out:
         /*
          * Unconditionally clear rotate_necessary; if ctx_flexible_sched_in()
          * finds there are unschedulable events, it will set it again.
          */
         pmu_ctx->rotate_necessary = 0;
 
         return event;
 }
 
 static bool perf_rotate_context(struct perf_cpu_pmu_context *cpc)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_pmu_context *cpu_epc, *task_epc = NULL;
         struct perf_event *cpu_event = NULL, *task_event = NULL;
         int cpu_rotate, task_rotate;
         struct pmu *pmu;
 
         /*
          * Since we run this from IRQ context, nobody can install new
          * events, thus the event count values are stable.
          */
 
         cpu_epc = &cpc->epc;
         pmu = cpu_epc->pmu;
         task_epc = cpc->task_epc;
 
         cpu_rotate = cpu_epc->rotate_necessary;
         task_rotate = task_epc ? task_epc->rotate_necessary : 0;
 
         if (!(cpu_rotate || task_rotate))
                 return false;
 
         perf_ctx_lock(cpuctx, cpuctx->task_ctx);
         perf_pmu_disable(pmu);
 
         if (task_rotate)
                 task_event = ctx_event_to_rotate(task_epc);
         if (cpu_rotate)
                 cpu_event = ctx_event_to_rotate(cpu_epc);
 
         /*
          * As per the order given at ctx_resched() first 'pop' task flexible
          * and then, if needed CPU flexible.
          */
         if (task_event || (task_epc && cpu_event)) {
                 update_context_time(task_epc->ctx);
                 __pmu_ctx_sched_out(task_epc, EVENT_FLEXIBLE);
         }
 
         if (cpu_event) {
                 update_context_time(&cpuctx->ctx);
                 __pmu_ctx_sched_out(cpu_epc, EVENT_FLEXIBLE);
                 rotate_ctx(&cpuctx->ctx, cpu_event);
                 __pmu_ctx_sched_in(&cpuctx->ctx, pmu);
         }
 
         if (task_event)
                 rotate_ctx(task_epc->ctx, task_event);
 
         if (task_event || (task_epc && cpu_event))
                 __pmu_ctx_sched_in(task_epc->ctx, pmu);
 
         perf_pmu_enable(pmu);
         perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
 
         return true;
 }
 
 void perf_event_task_tick(void)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_context *ctx;
         int throttled;
 
         lockdep_assert_irqs_disabled();
 
         __this_cpu_inc(perf_throttled_seq);
         throttled = __this_cpu_xchg(perf_throttled_count, 0);
         tick_dep_clear_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
 
         perf_adjust_freq_unthr_context(&cpuctx->ctx, !!throttled);
 
         rcu_read_lock();
         ctx = rcu_dereference(current->perf_event_ctxp);
         if (ctx)
                 perf_adjust_freq_unthr_context(ctx, !!throttled);
         rcu_read_unlock();
 }
 
 static int event_enable_on_exec(struct perf_event *event,
                                 struct perf_event_context *ctx)
 {
         if (!event->attr.enable_on_exec)
                 return 0;
 
         event->attr.enable_on_exec = 0;
         if (event->state >= PERF_EVENT_STATE_INACTIVE)
                 return 0;
 
         perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
 
         return 1;
 }
 
 /*
  * Enable all of a task's events that have been marked enable-on-exec.
  * This expects task == current.
  */
 static void perf_event_enable_on_exec(struct perf_event_context *ctx)
 {
         struct perf_event_context *clone_ctx = NULL;
         enum event_type_t event_type = 0;
         struct perf_cpu_context *cpuctx;
         struct perf_event *event;
         unsigned long flags;
         int enabled = 0;
 
         local_irq_save(flags);
         if (WARN_ON_ONCE(current->perf_event_ctxp != ctx))
                 goto out;
 
         if (!ctx->nr_events)
                 goto out;
 
         cpuctx = this_cpu_ptr(&perf_cpu_context);
         perf_ctx_lock(cpuctx, ctx);
         ctx_sched_out(ctx, EVENT_TIME);
 
         list_for_each_entry(event, &ctx->event_list, event_entry) {
                 enabled |= event_enable_on_exec(event, ctx);
                 event_type |= get_event_type(event);
         }
 
         /*
          * Unclone and reschedule this context if we enabled any event.
          */
         if (enabled) {
                 clone_ctx = unclone_ctx(ctx);
                 ctx_resched(cpuctx, ctx, event_type);
         } else {
                 ctx_sched_in(ctx, EVENT_TIME);
         }
         perf_ctx_unlock(cpuctx, ctx);
 
 out:
         local_irq_restore(flags);
 
         if (clone_ctx)
                 put_ctx(clone_ctx);
 }
 
 static void perf_remove_from_owner(struct perf_event *event);
 static void perf_event_exit_event(struct perf_event *event,
                                   struct perf_event_context *ctx);
 
 /*
  * Removes all events from the current task that have been marked
  * remove-on-exec, and feeds their values back to parent events.
  */
 static void perf_event_remove_on_exec(struct perf_event_context *ctx)
 {
         struct perf_event_context *clone_ctx = NULL;
         struct perf_event *event, *next;
         unsigned long flags;
         bool modified = false;
 
         mutex_lock(&ctx->mutex);
 
         if (WARN_ON_ONCE(ctx->task != current))
                 goto unlock;
 
         list_for_each_entry_safe(event, next, &ctx->event_list, event_entry) {
                 if (!event->attr.remove_on_exec)
                         continue;
 
                 if (!is_kernel_event(event))
                         perf_remove_from_owner(event);
 
                 modified = true;
 
                 perf_event_exit_event(event, ctx);
         }
 
         raw_spin_lock_irqsave(&ctx->lock, flags);
         if (modified)
                 clone_ctx = unclone_ctx(ctx);
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
 unlock:
         mutex_unlock(&ctx->mutex);
 
         if (clone_ctx)
                 put_ctx(clone_ctx);
 }
 
 struct perf_read_data {
         struct perf_event *event;
         bool group;
         int ret;
 };
 
 static int __perf_event_read_cpu(struct perf_event *event, int event_cpu)
 {
         u16 local_pkg, event_pkg;
 
         if ((unsigned)event_cpu >= nr_cpu_ids)
                 return event_cpu;
 
         if (event->group_caps & PERF_EV_CAP_READ_ACTIVE_PKG) {
                 int local_cpu = smp_processor_id();
 
                 event_pkg = topology_physical_package_id(event_cpu);
                 local_pkg = topology_physical_package_id(local_cpu);
 
                 if (event_pkg == local_pkg)
                         return local_cpu;
         }
 
         return event_cpu;
 }
 
 /*
  * Cross CPU call to read the hardware event
  */
 static void __perf_event_read(void *info)
 {
         struct perf_read_data *data = info;
         struct perf_event *sub, *event = data->event;
         struct perf_event_context *ctx = event->ctx;
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct pmu *pmu = event->pmu;
 
         /*
          * If this is a task context, we need to check whether it is
          * the current task context of this cpu.  If not it has been
          * scheduled out before the smp call arrived.  In that case
          * event->count would have been updated to a recent sample
          * when the event was scheduled out.
          */
         if (ctx->task && cpuctx->task_ctx != ctx)
                 return;
 
         raw_spin_lock(&ctx->lock);
         if (ctx->is_active & EVENT_TIME) {
                 update_context_time(ctx);
                 update_cgrp_time_from_event(event);
         }
 
         perf_event_update_time(event);
         if (data->group)
                 perf_event_update_sibling_time(event);
 
         if (event->state != PERF_EVENT_STATE_ACTIVE)
                 goto unlock;
 
         if (!data->group) {
                 pmu->read(event);
                 data->ret = 0;
                 goto unlock;
         }
 
         pmu->start_txn(pmu, PERF_PMU_TXN_READ);
 
         pmu->read(event);
 
         for_each_sibling_event(sub, event) {
                 if (sub->state == PERF_EVENT_STATE_ACTIVE) {
                         /*
                          * Use sibling's PMU rather than @event's since
                          * sibling could be on different (eg: software) PMU.
                          */
                         sub->pmu->read(sub);
                 }
         }
 
         data->ret = pmu->commit_txn(pmu);
 
 unlock:
         raw_spin_unlock(&ctx->lock);
 }
 
 static inline u64 perf_event_count(struct perf_event *event)
 {
         return local64_read(&event->count) + atomic64_read(&event->child_count);
 }
 
 static void calc_timer_values(struct perf_event *event,
                                 u64 *now,
                                 u64 *enabled,
                                 u64 *running)
 {
         u64 ctx_time;
 
         *now = perf_clock();
         ctx_time = perf_event_time_now(event, *now);
         __perf_update_times(event, ctx_time, enabled, running);
 }
 
 /*
  * NMI-safe method to read a local event, that is an event that
  * is:
  *   - either for the current task, or for this CPU
  *   - does not have inherit set, for inherited task events
  *     will not be local and we cannot read them atomically
  *   - must not have a pmu::count method
  */
 int perf_event_read_local(struct perf_event *event, u64 *value,
                           u64 *enabled, u64 *running)
 {
         unsigned long flags;
         int event_oncpu;
         int event_cpu;
         int ret = 0;
 
         /*
          * Disabling interrupts avoids all counter scheduling (context
          * switches, timer based rotation and IPIs).
          */
         local_irq_save(flags);
 
         /*
          * It must not be an event with inherit set, we cannot read
          * all child counters from atomic context.
          */
         if (event->attr.inherit) {
                 ret = -EOPNOTSUPP;
                 goto out;
         }
 
         /* If this is a per-task event, it must be for current */
         if ((event->attach_state & PERF_ATTACH_TASK) &&
             event->hw.target != current) {
                 ret = -EINVAL;
                 goto out;
         }
 
         /*
          * Get the event CPU numbers, and adjust them to local if the event is
          * a per-package event that can be read locally
          */
         event_oncpu = __perf_event_read_cpu(event, event->oncpu);
         event_cpu = __perf_event_read_cpu(event, event->cpu);
 
         /* If this is a per-CPU event, it must be for this CPU */
         if (!(event->attach_state & PERF_ATTACH_TASK) &&
             event_cpu != smp_processor_id()) {
                 ret = -EINVAL;
                 goto out;
         }
 
         /* If this is a pinned event it must be running on this CPU */
         if (event->attr.pinned && event_oncpu != smp_processor_id()) {
                 ret = -EBUSY;
                 goto out;
         }
 
         /*
          * If the event is currently on this CPU, its either a per-task event,
          * or local to this CPU. Furthermore it means its ACTIVE (otherwise
          * oncpu == -1).
          */
         if (event_oncpu == smp_processor_id())
                 event->pmu->read(event);
 
         *value = local64_read(&event->count);
         if (enabled || running) {
                 u64 __enabled, __running, __now;
 
                 calc_timer_values(event, &__now, &__enabled, &__running);
                 if (enabled)
                         *enabled = __enabled;
                 if (running)
                         *running = __running;
         }
 out:
         local_irq_restore(flags);
 
         return ret;
 }
 
 static int perf_event_read(struct perf_event *event, bool group)
 {
         enum perf_event_state state = READ_ONCE(event->state);
         int event_cpu, ret = 0;
 
         /*
          * If event is enabled and currently active on a CPU, update the
          * value in the event structure:
          */
 again:
         if (state == PERF_EVENT_STATE_ACTIVE) {
                 struct perf_read_data data;
 
                 /*
                  * Orders the ->state and ->oncpu loads such that if we see
                  * ACTIVE we must also see the right ->oncpu.
                  *
                  * Matches the smp_wmb() from event_sched_in().
                  */
                 smp_rmb();
 
                 event_cpu = READ_ONCE(event->oncpu);
                 if ((unsigned)event_cpu >= nr_cpu_ids)
                         return 0;
 
                 data = (struct perf_read_data){
                         .event = event,
                         .group = group,
                         .ret = 0,
                 };
 
                 preempt_disable();
                 event_cpu = __perf_event_read_cpu(event, event_cpu);
 
                 /*
                  * Purposely ignore the smp_call_function_single() return
                  * value.
                  *
                  * If event_cpu isn't a valid CPU it means the event got
                  * scheduled out and that will have updated the event count.
                  *
                  * Therefore, either way, we'll have an up-to-date event count
                  * after this.
                  */
                 (void)smp_call_function_single(event_cpu, __perf_event_read, &data, 1);
                 preempt_enable();
                 ret = data.ret;
 
         } else if (state == PERF_EVENT_STATE_INACTIVE) {
                 struct perf_event_context *ctx = event->ctx;
                 unsigned long flags;
 
                 raw_spin_lock_irqsave(&ctx->lock, flags);
                 state = event->state;
                 if (state != PERF_EVENT_STATE_INACTIVE) {
                         raw_spin_unlock_irqrestore(&ctx->lock, flags);
                         goto again;
                 }
 
                 /*
                  * May read while context is not active (e.g., thread is
                  * blocked), in that case we cannot update context time
                  */
                 if (ctx->is_active & EVENT_TIME) {
                         update_context_time(ctx);
                         update_cgrp_time_from_event(event);
                 }
 
                 perf_event_update_time(event);
                 if (group)
                         perf_event_update_sibling_time(event);
                 raw_spin_unlock_irqrestore(&ctx->lock, flags);
         }
 
         return ret;
 }
 
 /*
  * Initialize the perf_event context in a task_struct:
  */
 static void __perf_event_init_context(struct perf_event_context *ctx)
 {
         raw_spin_lock_init(&ctx->lock);
         mutex_init(&ctx->mutex);
         INIT_LIST_HEAD(&ctx->pmu_ctx_list);
         perf_event_groups_init(&ctx->pinned_groups);
         perf_event_groups_init(&ctx->flexible_groups);
         INIT_LIST_HEAD(&ctx->event_list);
         refcount_set(&ctx->refcount, 1);
 }
 
 static void
 __perf_init_event_pmu_context(struct perf_event_pmu_context *epc, struct pmu *pmu)
 {
         epc->pmu = pmu;
         INIT_LIST_HEAD(&epc->pmu_ctx_entry);
         INIT_LIST_HEAD(&epc->pinned_active);
         INIT_LIST_HEAD(&epc->flexible_active);
         atomic_set(&epc->refcount, 1);
 }
 
 static struct perf_event_context *
 alloc_perf_context(struct task_struct *task)
 {
         struct perf_event_context *ctx;
 
         ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
         if (!ctx)
                 return NULL;
 
         __perf_event_init_context(ctx);
         if (task)
                 ctx->task = get_task_struct(task);
 
         return ctx;
 }
 
 static struct task_struct *
 find_lively_task_by_vpid(pid_t vpid)
 {
         struct task_struct *task;
 
         rcu_read_lock();
         if (!vpid)
                 task = current;
         else
                 task = find_task_by_vpid(vpid);
         if (task)
                 get_task_struct(task);
         rcu_read_unlock();
 
         if (!task)
                 return ERR_PTR(-ESRCH);
 
         return task;
 }
 
 /*
  * Returns a matching context with refcount and pincount.
  */
 static struct perf_event_context *
 find_get_context(struct task_struct *task, struct perf_event *event)
 {
         struct perf_event_context *ctx, *clone_ctx = NULL;
         struct perf_cpu_context *cpuctx;
         unsigned long flags;
         int err;
 
         if (!task) {
                 /* Must be root to operate on a CPU event: */
                 err = perf_allow_cpu(&event->attr);
                 if (err)
                         return ERR_PTR(err);
 
                 cpuctx = per_cpu_ptr(&perf_cpu_context, event->cpu);
                 ctx = &cpuctx->ctx;
                 get_ctx(ctx);
                 raw_spin_lock_irqsave(&ctx->lock, flags);
                 ++ctx->pin_count;
                 raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
                 return ctx;
         }
 
         err = -EINVAL;
 retry:
         ctx = perf_lock_task_context(task, &flags);
         if (ctx) {
                 clone_ctx = unclone_ctx(ctx);
                 ++ctx->pin_count;
 
                 raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
                 if (clone_ctx)
                         put_ctx(clone_ctx);
         } else {
                 ctx = alloc_perf_context(task);
                 err = -ENOMEM;
                 if (!ctx)
                         goto errout;
 
                 err = 0;
                 mutex_lock(&task->perf_event_mutex);
                 /*
                  * If it has already passed perf_event_exit_task().
                  * we must see PF_EXITING, it takes this mutex too.
                  */
                 if (task->flags & PF_EXITING)
                         err = -ESRCH;
                 else if (task->perf_event_ctxp)
                         err = -EAGAIN;
                 else {
                         get_ctx(ctx);
                         ++ctx->pin_count;
                         rcu_assign_pointer(task->perf_event_ctxp, ctx);
                 }
                 mutex_unlock(&task->perf_event_mutex);
 
                 if (unlikely(err)) {
                         put_ctx(ctx);
 
                         if (err == -EAGAIN)
                                 goto retry;
                         goto errout;
                 }
         }
 
         return ctx;
 
 errout:
         return ERR_PTR(err);
 }
 
 static struct perf_event_pmu_context *
 find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
                      struct perf_event *event)
 {
         struct perf_event_pmu_context *new = NULL, *epc;
         void *task_ctx_data = NULL;
 
         if (!ctx->task) {
                 /*
                  * perf_pmu_migrate_context() / __perf_pmu_install_event()
                  * relies on the fact that find_get_pmu_context() cannot fail
                  * for CPU contexts.
                  */
                 struct perf_cpu_pmu_context *cpc;
 
                 cpc = per_cpu_ptr(pmu->cpu_pmu_context, event->cpu);
                 epc = &cpc->epc;
                 raw_spin_lock_irq(&ctx->lock);
                 if (!epc->ctx) {
                         atomic_set(&epc->refcount, 1);
                         epc->embedded = 1;
                         list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
                         epc->ctx = ctx;
                 } else {
                         WARN_ON_ONCE(epc->ctx != ctx);
                         atomic_inc(&epc->refcount);
                 }
                 raw_spin_unlock_irq(&ctx->lock);
                 return epc;
         }
 
         new = kzalloc(sizeof(*epc), GFP_KERNEL);
         if (!new)
                 return ERR_PTR(-ENOMEM);
 
         if (event->attach_state & PERF_ATTACH_TASK_DATA) {
                 task_ctx_data = alloc_task_ctx_data(pmu);
                 if (!task_ctx_data) {
                         kfree(new);
                         return ERR_PTR(-ENOMEM);
                 }
         }
 
         __perf_init_event_pmu_context(new, pmu);
 
         /*
          * XXX
          *
          * lockdep_assert_held(&ctx->mutex);
          *
          * can't because perf_event_init_task() doesn't actually hold the
          * child_ctx->mutex.
          */
 
         raw_spin_lock_irq(&ctx->lock);
         list_for_each_entry(epc, &ctx->pmu_ctx_list, pmu_ctx_entry) {
                 if (epc->pmu == pmu) {
                         WARN_ON_ONCE(epc->ctx != ctx);
                         atomic_inc(&epc->refcount);
                         goto found_epc;
                 }
         }
 
         epc = new;
         new = NULL;
 
         list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
         epc->ctx = ctx;
 
 found_epc:
         if (task_ctx_data && !epc->task_ctx_data) {
                 epc->task_ctx_data = task_ctx_data;
                 task_ctx_data = NULL;
                 ctx->nr_task_data++;
         }
         raw_spin_unlock_irq(&ctx->lock);
 
         free_task_ctx_data(pmu, task_ctx_data);
         kfree(new);
 
         return epc;
 }
 
 static void get_pmu_ctx(struct perf_event_pmu_context *epc)
 {
         WARN_ON_ONCE(!atomic_inc_not_zero(&epc->refcount));
 }
 
 static void free_epc_rcu(struct rcu_head *head)
 {
         struct perf_event_pmu_context *epc = container_of(head, typeof(*epc), rcu_head);
 
         kfree(epc->task_ctx_data);
         kfree(epc);
 }
 
 static void put_pmu_ctx(struct perf_event_pmu_context *epc)
 {
         struct perf_event_context *ctx = epc->ctx;
         unsigned long flags;
 
         /*
          * XXX
          *
          * lockdep_assert_held(&ctx->mutex);
          *
          * can't because of the call-site in _free_event()/put_event()
          * which isn't always called under ctx->mutex.
          */
         if (!atomic_dec_and_raw_lock_irqsave(&epc->refcount, &ctx->lock, flags))
                 return;
 
         WARN_ON_ONCE(list_empty(&epc->pmu_ctx_entry));
 
         list_del_init(&epc->pmu_ctx_entry);
         epc->ctx = NULL;
 
         WARN_ON_ONCE(!list_empty(&epc->pinned_active));
         WARN_ON_ONCE(!list_empty(&epc->flexible_active));
 
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
         if (epc->embedded)
                 return;
 
         call_rcu(&epc->rcu_head, free_epc_rcu);
 }
 
 static void perf_event_free_filter(struct perf_event *event);
 
 static void free_event_rcu(struct rcu_head *head)
 {
         struct perf_event *event = container_of(head, typeof(*event), rcu_head);
 
         if (event->ns)
                 put_pid_ns(event->ns);
         perf_event_free_filter(event);
         kmem_cache_free(perf_event_cache, event);
 }
 
 static void ring_buffer_attach(struct perf_event *event,
                                struct perf_buffer *rb);
 
 static void detach_sb_event(struct perf_event *event)
 {
         struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
 
         raw_spin_lock(&pel->lock);
         list_del_rcu(&event->sb_list);
         raw_spin_unlock(&pel->lock);
 }
 
 static bool is_sb_event(struct perf_event *event)
 {
         struct perf_event_attr *attr = &event->attr;
 
         if (event->parent)
                 return false;
 
         if (event->attach_state & PERF_ATTACH_TASK)
                 return false;
 
         if (attr->mmap || attr->mmap_data || attr->mmap2 ||
             attr->comm || attr->comm_exec ||
             attr->task || attr->ksymbol ||
             attr->context_switch || attr->text_poke ||
             attr->bpf_event)
                 return true;
         return false;
 }
 
 static void unaccount_pmu_sb_event(struct perf_event *event)
 {
         if (is_sb_event(event))
                 detach_sb_event(event);
 }
 
 #ifdef CONFIG_NO_HZ_FULL
 static DEFINE_SPINLOCK(nr_freq_lock);
 #endif
 
 static void unaccount_freq_event_nohz(void)
 {
 #ifdef CONFIG_NO_HZ_FULL
         spin_lock(&nr_freq_lock);
         if (atomic_dec_and_test(&nr_freq_events))
                 tick_nohz_dep_clear(TICK_DEP_BIT_PERF_EVENTS);
         spin_unlock(&nr_freq_lock);
 #endif
 }
 
 static void unaccount_freq_event(void)
 {
         if (tick_nohz_full_enabled())
                 unaccount_freq_event_nohz();
         else
                 atomic_dec(&nr_freq_events);
 }
 
 static void unaccount_event(struct perf_event *event)
 {
         bool dec = false;
 
         if (event->parent)
                 return;
 
         if (event->attach_state & (PERF_ATTACH_TASK | PERF_ATTACH_SCHED_CB))
                 dec = true;
         if (event->attr.mmap || event->attr.mmap_data)
                 atomic_dec(&nr_mmap_events);
         if (event->attr.build_id)
                 atomic_dec(&nr_build_id_events);
         if (event->attr.comm)
                 atomic_dec(&nr_comm_events);
         if (event->attr.namespaces)
                 atomic_dec(&nr_namespaces_events);
         if (event->attr.cgroup)
                 atomic_dec(&nr_cgroup_events);
         if (event->attr.task)
                 atomic_dec(&nr_task_events);
         if (event->attr.freq)
                 unaccount_freq_event();
         if (event->attr.context_switch) {
                 dec = true;
                 atomic_dec(&nr_switch_events);
         }
         if (is_cgroup_event(event))
                 dec = true;
         if (has_branch_stack(event))
                 dec = true;
         if (event->attr.ksymbol)
                 atomic_dec(&nr_ksymbol_events);
         if (event->attr.bpf_event)
                 atomic_dec(&nr_bpf_events);
         if (event->attr.text_poke)
                 atomic_dec(&nr_text_poke_events);
 
         if (dec) {
                 if (!atomic_add_unless(&perf_sched_count, -1, 1))
                         schedule_delayed_work(&perf_sched_work, HZ);
         }
 
         unaccount_pmu_sb_event(event);
 }
 
 static void perf_sched_delayed(struct work_struct *work)
 {
         mutex_lock(&perf_sched_mutex);
         if (atomic_dec_and_test(&perf_sched_count))
                 static_branch_disable(&perf_sched_events);
         mutex_unlock(&perf_sched_mutex);
 }
 
 /*
  * The following implement mutual exclusion of events on "exclusive" pmus
  * (PERF_PMU_CAP_EXCLUSIVE). Such pmus can only have one event scheduled
  * at a time, so we disallow creating events that might conflict, namely:
  *
  *  1) cpu-wide events in the presence of per-task events,
  *  2) per-task events in the presence of cpu-wide events,
  *  3) two matching events on the same perf_event_context.
  *
  * The former two cases are handled in the allocation path (perf_event_alloc(),
  * _free_event()), the latter -- before the first perf_install_in_context().
  */
 static int exclusive_event_init(struct perf_event *event)
 {
         struct pmu *pmu = event->pmu;
 
         if (!is_exclusive_pmu(pmu))
                 return 0;
 
         /*
          * Prevent co-existence of per-task and cpu-wide events on the
          * same exclusive pmu.
          *
          * Negative pmu::exclusive_cnt means there are cpu-wide
          * events on this "exclusive" pmu, positive means there are
          * per-task events.
          *
          * Since this is called in perf_event_alloc() path, event::ctx
          * doesn't exist yet; it is, however, safe to use PERF_ATTACH_TASK
          * to mean "per-task event", because unlike other attach states it
          * never gets cleared.
          */
         if (event->attach_state & PERF_ATTACH_TASK) {
                 if (!atomic_inc_unless_negative(&pmu->exclusive_cnt))
                         return -EBUSY;
         } else {
                 if (!atomic_dec_unless_positive(&pmu->exclusive_cnt))
                         return -EBUSY;
         }
 
         return 0;
 }
 
 static void exclusive_event_destroy(struct perf_event *event)
 {
         struct pmu *pmu = event->pmu;
 
         if (!is_exclusive_pmu(pmu))
                 return;
 
         /* see comment in exclusive_event_init() */
         if (event->attach_state & PERF_ATTACH_TASK)
                 atomic_dec(&pmu->exclusive_cnt);
         else
                 atomic_inc(&pmu->exclusive_cnt);
 }
 
 static bool exclusive_event_match(struct perf_event *e1, struct perf_event *e2)
 {
         if ((e1->pmu == e2->pmu) &&
             (e1->cpu == e2->cpu ||
              e1->cpu == -1 ||
              e2->cpu == -1))
                 return true;
         return false;
 }
 
 static bool exclusive_event_installable(struct perf_event *event,
                                         struct perf_event_context *ctx)
 {
         struct perf_event *iter_event;
         struct pmu *pmu = event->pmu;
 
         lockdep_assert_held(&ctx->mutex);
 
         if (!is_exclusive_pmu(pmu))
                 return true;
 
         list_for_each_entry(iter_event, &ctx->event_list, event_entry) {
                 if (exclusive_event_match(iter_event, event))
                         return false;
         }
 
         return true;
 }
 
 static void perf_addr_filters_splice(struct perf_event *event,
                                        struct list_head *head);
 
 static void perf_pending_task_sync(struct perf_event *event)
 {
         struct callback_head *head = &event->pending_task;
 
         if (!event->pending_work)
                 return;
         /*
          * If the task is queued to the current task's queue, we
          * obviously can't wait for it to complete. Simply cancel it.
          */
         if (task_work_cancel(current, head)) {
                 event->pending_work = 0;
                 local_dec(&event->ctx->nr_pending);
                 return;
         }
 
         /*
          * All accesses related to the event are within the same RCU section in
          * perf_pending_task(). The RCU grace period before the event is freed
          * will make sure all those accesses are complete by then.
          */
         rcuwait_wait_event(&event->pending_work_wait, !event->pending_work, TASK_UNINTERRUPTIBLE);
 }
 
 static void _free_event(struct perf_event *event)
 {
         irq_work_sync(&event->pending_irq);
         irq_work_sync(&event->pending_disable_irq);
         perf_pending_task_sync(event);
 
         unaccount_event(event);
 
         security_perf_event_free(event);
 
         if (event->rb) {
                 /*
                  * Can happen when we close an event with re-directed output.
                  *
                  * Since we have a 0 refcount, perf_mmap_close() will skip
                  * over us; possibly making our ring_buffer_put() the last.
                  */
                 mutex_lock(&event->mmap_mutex);
                 ring_buffer_attach(event, NULL);
                 mutex_unlock(&event->mmap_mutex);
         }
 
         if (is_cgroup_event(event))
                 perf_detach_cgroup(event);
 
         if (!event->parent) {
                 if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
                         put_callchain_buffers();
         }
 
         perf_event_free_bpf_prog(event);
         perf_addr_filters_splice(event, NULL);
         kfree(event->addr_filter_ranges);
 
         if (event->destroy)
                 event->destroy(event);
 
         /*
          * Must be after ->destroy(), due to uprobe_perf_close() using
          * hw.target.
          */
         if (event->hw.target)
                 put_task_struct(event->hw.target);
 
         if (event->pmu_ctx)
                 put_pmu_ctx(event->pmu_ctx);
 
         /*
          * perf_event_free_task() relies on put_ctx() being 'last', in particular
          * all task references must be cleaned up.
          */
         if (event->ctx)
                 put_ctx(event->ctx);
 
         exclusive_event_destroy(event);
         module_put(event->pmu->module);
 
         call_rcu(&event->rcu_head, free_event_rcu);
 }
 
 /*
  * Used to free events which have a known refcount of 1, such as in error paths
  * where the event isn't exposed yet and inherited events.
  */
 static void free_event(struct perf_event *event)
 {
         if (WARN(atomic_long_cmpxchg(&event->refcount, 1, 0) != 1,
                                 "unexpected event refcount: %ld; ptr=%p\n",
                                 atomic_long_read(&event->refcount), event)) {
                 /* leak to avoid use-after-free */
                 return;
         }
 
         _free_event(event);
 }
 
 /*
  * Remove user event from the owner task.
  */
 static void perf_remove_from_owner(struct perf_event *event)
 {
         struct task_struct *owner;
 
         rcu_read_lock();
         /*
          * Matches the smp_store_release() in perf_event_exit_task(). If we
          * observe !owner it means the list deletion is complete and we can
          * indeed free this event, otherwise we need to serialize on
          * owner->perf_event_mutex.
          */
         owner = READ_ONCE(event->owner);
         if (owner) {
                 /*
                  * Since delayed_put_task_struct() also drops the last
                  * task reference we can safely take a new reference
                  * while holding the rcu_read_lock().
                  */
                 get_task_struct(owner);
         }
         rcu_read_unlock();
 
         if (owner) {
                 /*
                  * If we're here through perf_event_exit_task() we're already
                  * holding ctx->mutex which would be an inversion wrt. the
                  * normal lock order.
                  *
                  * However we can safely take this lock because its the child
                  * ctx->mutex.
                  */
                 mutex_lock_nested(&owner->perf_event_mutex, SINGLE_DEPTH_NESTING);
 
                 /*
                  * We have to re-check the event->owner field, if it is cleared
                  * we raced with perf_event_exit_task(), acquiring the mutex
                  * ensured they're done, and we can proceed with freeing the
                  * event.
                  */
                 if (event->owner) {
                         list_del_init(&event->owner_entry);
                         smp_store_release(&event->owner, NULL);
                 }
                 mutex_unlock(&owner->perf_event_mutex);
                 put_task_struct(owner);
         }
 }
 
 static void put_event(struct perf_event *event)
 {
         if (!atomic_long_dec_and_test(&event->refcount))
                 return;
 
         _free_event(event);
 }
 
 /*
  * Kill an event dead; while event:refcount will preserve the event
  * object, it will not preserve its functionality. Once the last 'user'
  * gives up the object, we'll destroy the thing.
  */
 int perf_event_release_kernel(struct perf_event *event)
 {
         struct perf_event_context *ctx = event->ctx;
         struct perf_event *child, *tmp;
         LIST_HEAD(free_list);
 
         /*
          * If we got here through err_alloc: free_event(event); we will not
          * have attached to a context yet.
          */
         if (!ctx) {
                 WARN_ON_ONCE(event->attach_state &
                                 (PERF_ATTACH_CONTEXT|PERF_ATTACH_GROUP));
                 goto no_ctx;
         }
 
         if (!is_kernel_event(event))
                 perf_remove_from_owner(event);
 
         ctx = perf_event_ctx_lock(event);
         WARN_ON_ONCE(ctx->parent_ctx);
 
         /*
          * Mark this event as STATE_DEAD, there is no external reference to it
          * anymore.
          *
          * Anybody acquiring event->child_mutex after the below loop _must_
          * also see this, most importantly inherit_event() which will avoid
          * placing more children on the list.
          *
          * Thus this guarantees that we will in fact observe and kill _ALL_
          * child events.
          */
         perf_remove_from_context(event, DETACH_GROUP|DETACH_DEAD);
 
         perf_event_ctx_unlock(event, ctx);
 
 again:
         mutex_lock(&event->child_mutex);
         list_for_each_entry(child, &event->child_list, child_list) {
                 void *var = NULL;
 
                 /*
                  * Cannot change, child events are not migrated, see the
                  * comment with perf_event_ctx_lock_nested().
                  */
                 ctx = READ_ONCE(child->ctx);
                 /*
                  * Since child_mutex nests inside ctx::mutex, we must jump
                  * through hoops. We start by grabbing a reference on the ctx.
                  *
                  * Since the event cannot get freed while we hold the
                  * child_mutex, the context must also exist and have a !0
                  * reference count.
                  */
                 get_ctx(ctx);
 
                 /*
                  * Now that we have a ctx ref, we can drop child_mutex, and
                  * acquire ctx::mutex without fear of it going away. Then we
                  * can re-acquire child_mutex.
                  */
                 mutex_unlock(&event->child_mutex);
                 mutex_lock(&ctx->mutex);
                 mutex_lock(&event->child_mutex);
 
                 /*
                  * Now that we hold ctx::mutex and child_mutex, revalidate our
                  * state, if child is still the first entry, it didn't get freed
                  * and we can continue doing so.
                  */
                 tmp = list_first_entry_or_null(&event->child_list,
                                                struct perf_event, child_list);
                 if (tmp == child) {
                         perf_remove_from_context(child, DETACH_GROUP);
                         list_move(&child->child_list, &free_list);
                         /*
                          * This matches the refcount bump in inherit_event();
                          * this can't be the last reference.
                          */
                         put_event(event);
                 } else {
                         var = &ctx->refcount;
                 }
 
                 mutex_unlock(&event->child_mutex);
                 mutex_unlock(&ctx->mutex);
                 put_ctx(ctx);
 
                 if (var) {
                         /*
                          * If perf_event_free_task() has deleted all events from the
                          * ctx while the child_mutex got released above, make sure to
                          * notify about the preceding put_ctx().
                          */
                         smp_mb(); /* pairs with wait_var_event() */
                         wake_up_var(var);
                 }
                 goto again;
         }
         mutex_unlock(&event->child_mutex);
 
         list_for_each_entry_safe(child, tmp, &free_list, child_list) {
                 void *var = &child->ctx->refcount;
 
                 list_del(&child->child_list);
                 free_event(child);
 
                 /*
                  * Wake any perf_event_free_task() waiting for this event to be
                  * freed.
                  */
                 smp_mb(); /* pairs with wait_var_event() */
                 wake_up_var(var);
         }
 
 no_ctx:
         put_event(event); /* Must be the 'last' reference */
         return 0;
 }
 EXPORT_SYMBOL_GPL(perf_event_release_kernel);
 
 /*
  * Called when the last reference to the file is gone.
  */
 static int perf_release(struct inode *inode, struct file *file)
 {
         perf_event_release_kernel(file->private_data);
         return 0;
 }
 
 static u64 __perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
 {
         struct perf_event *child;
         u64 total = 0;
 
         *enabled = 0;
         *running = 0;
 
         mutex_lock(&event->child_mutex);
 
         (void)perf_event_read(event, false);
         total += perf_event_count(event);
 
         *enabled += event->total_time_enabled +
                         atomic64_read(&event->child_total_time_enabled);
         *running += event->total_time_running +
                         atomic64_read(&event->child_total_time_running);
 
         list_for_each_entry(child, &event->child_list, child_list) {
                 (void)perf_event_read(child, false);
                 total += perf_event_count(child);
                 *enabled += child->total_time_enabled;
                 *running += child->total_time_running;
         }
         mutex_unlock(&event->child_mutex);
 
         return total;
 }
 
 u64 perf_event_read_value(struct perf_event *event, u64 *enabled, u64 *running)
 {
         struct perf_event_context *ctx;
         u64 count;
 
         ctx = perf_event_ctx_lock(event);
         count = __perf_event_read_value(event, enabled, running);
         perf_event_ctx_unlock(event, ctx);
 
         return count;
 }
 EXPORT_SYMBOL_GPL(perf_event_read_value);
 
 static int __perf_read_group_add(struct perf_event *leader,
                                         u64 read_format, u64 *values)
 {
         struct perf_event_context *ctx = leader->ctx;
         struct perf_event *sub, *parent;
         unsigned long flags;
         int n = 1; /* skip @nr */
         int ret;
 
         ret = perf_event_read(leader, true);
         if (ret)
                 return ret;
 
         raw_spin_lock_irqsave(&ctx->lock, flags);
         /*
          * Verify the grouping between the parent and child (inherited)
          * events is still in tact.
          *
          * Specifically:
          *  - leader->ctx->lock pins leader->sibling_list
          *  - parent->child_mutex pins parent->child_list
          *  - parent->ctx->mutex pins parent->sibling_list
          *
          * Because parent->ctx != leader->ctx (and child_list nests inside
          * ctx->mutex), group destruction is not atomic between children, also
          * see perf_event_release_kernel(). Additionally, parent can grow the
          * group.
          *
          * Therefore it is possible to have parent and child groups in a
          * different configuration and summing over such a beast makes no sense
          * what so ever.
          *
          * Reject this.
          */
         parent = leader->parent;
         if (parent &&
             (parent->group_generation != leader->group_generation ||
              parent->nr_siblings != leader->nr_siblings)) {
                 ret = -ECHILD;
                 goto unlock;
         }
 
         /*
          * Since we co-schedule groups, {enabled,running} times of siblings
          * will be identical to those of the leader, so we only publish one
          * set.
          */
         if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
                 values[n++] += leader->total_time_enabled +
                         atomic64_read(&leader->child_total_time_enabled);
         }
 
         if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
                 values[n++] += leader->total_time_running +
                         atomic64_read(&leader->child_total_time_running);
         }
 
         /*
          * Write {count,id} tuples for every sibling.
          */
         values[n++] += perf_event_count(leader);
         if (read_format & PERF_FORMAT_ID)
                 values[n++] = primary_event_id(leader);
         if (read_format & PERF_FORMAT_LOST)
                 values[n++] = atomic64_read(&leader->lost_samples);
 
         for_each_sibling_event(sub, leader) {
                 values[n++] += perf_event_count(sub);
                 if (read_format & PERF_FORMAT_ID)
                         values[n++] = primary_event_id(sub);
                 if (read_format & PERF_FORMAT_LOST)
                         values[n++] = atomic64_read(&sub->lost_samples);
         }
 
 unlock:
         raw_spin_unlock_irqrestore(&ctx->lock, flags);
         return ret;
 }
 
 static int perf_read_group(struct perf_event *event,
                                    u64 read_format, char __user *buf)
 {
         struct perf_event *leader = event->group_leader, *child;
         struct perf_event_context *ctx = leader->ctx;
         int ret;
         u64 *values;
 
         lockdep_assert_held(&ctx->mutex);
 
         values = kzalloc(event->read_size, GFP_KERNEL);
         if (!values)
                 return -ENOMEM;
 
         values[0] = 1 + leader->nr_siblings;
 
         mutex_lock(&leader->child_mutex);
 
         ret = __perf_read_group_add(leader, read_format, values);
         if (ret)
                 goto unlock;
 
         list_for_each_entry(child, &leader->child_list, child_list) {
                 ret = __perf_read_group_add(child, read_format, values);
                 if (ret)
                         goto unlock;
         }
 
         mutex_unlock(&leader->child_mutex);
 
         ret = event->read_size;
         if (copy_to_user(buf, values, event->read_size))
                 ret = -EFAULT;
         goto out;
 
 unlock:
         mutex_unlock(&leader->child_mutex);
 out:
         kfree(values);
         return ret;
 }
 
 static int perf_read_one(struct perf_event *event,
                                  u64 read_format, char __user *buf)
 {
         u64 enabled, running;
         u64 values[5];
         int n = 0;
 
         values[n++] = __perf_event_read_value(event, &enabled, &running);
         if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
                 values[n++] = enabled;
         if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
                 values[n++] = running;
         if (read_format & PERF_FORMAT_ID)
                 values[n++] = primary_event_id(event);
         if (read_format & PERF_FORMAT_LOST)
                 values[n++] = atomic64_read(&event->lost_samples);
 
         if (copy_to_user(buf, values, n * sizeof(u64)))
                 return -EFAULT;
 
         return n * sizeof(u64);
 }
 
 static bool is_event_hup(struct perf_event *event)
 {
         bool no_children;
 
         if (event->state > PERF_EVENT_STATE_EXIT)
                 return false;
 
         mutex_lock(&event->child_mutex);
         no_children = list_empty(&event->child_list);
         mutex_unlock(&event->child_mutex);
         return no_children;
 }
 
 /*
  * Read the performance event - simple non blocking version for now
  */
 static ssize_t
 __perf_read(struct perf_event *event, char __user *buf, size_t count)
 {
         u64 read_format = event->attr.read_format;
         int ret;
 
         /*
          * Return end-of-file for a read on an event that is in
          * error state (i.e. because it was pinned but it couldn't be
          * scheduled on to the CPU at some point).
          */
         if (event->state == PERF_EVENT_STATE_ERROR)
                 return 0;
 
         if (count < event->read_size)
                 return -ENOSPC;
 
         WARN_ON_ONCE(event->ctx->parent_ctx);
         if (read_format & PERF_FORMAT_GROUP)
                 ret = perf_read_group(event, read_format, buf);
         else
                 ret = perf_read_one(event, read_format, buf);
 
         return ret;
 }
 
 static ssize_t
 perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 {
         struct perf_event *event = file->private_data;
         struct perf_event_context *ctx;
         int ret;
 
         ret = security_perf_event_read(event);
         if (ret)
                 return ret;
 
         ctx = perf_event_ctx_lock(event);
         ret = __perf_read(event, buf, count);
         perf_event_ctx_unlock(event, ctx);
 
         return ret;
 }
 
 static __poll_t perf_poll(struct file *file, poll_table *wait)
 {
         struct perf_event *event = file->private_data;
         struct perf_buffer *rb;
         __poll_t events = EPOLLHUP;
 
         poll_wait(file, &event->waitq, wait);
 
         if (is_event_hup(event))
                 return events;
 
         /*
          * Pin the event->rb by taking event->mmap_mutex; otherwise
          * perf_event_set_output() can swizzle our rb and make us miss wakeups.
          */
         mutex_lock(&event->mmap_mutex);
         rb = event->rb;
         if (rb)
                 events = atomic_xchg(&rb->poll, 0);
         mutex_unlock(&event->mmap_mutex);
         return events;
 }
 
 static void _perf_event_reset(struct perf_event *event)
 {
         (void)perf_event_read(event, false);
         local64_set(&event->count, 0);
         perf_event_update_userpage(event);
 }
 
 /* Assume it's not an event with inherit set. */
 u64 perf_event_pause(struct perf_event *event, bool reset)
 {
         struct perf_event_context *ctx;
         u64 count;
 
         ctx = perf_event_ctx_lock(event);
         WARN_ON_ONCE(event->attr.inherit);
         _perf_event_disable(event);
         count = local64_read(&event->count);
         if (reset)
                 local64_set(&event->count, 0);
         perf_event_ctx_unlock(event, ctx);
 
         return count;
 }
 EXPORT_SYMBOL_GPL(perf_event_pause);
 
 /*
  * Holding the top-level event's child_mutex means that any
  * descendant process that has inherited this event will block
  * in perf_event_exit_event() if it goes to exit, thus satisfying the
  * task existence requirements of perf_event_enable/disable.
  */
 static void perf_event_for_each_child(struct perf_event *event,
                                         void (*func)(struct perf_event *))
 {
         struct perf_event *child;
 
         WARN_ON_ONCE(event->ctx->parent_ctx);
 
         mutex_lock(&event->child_mutex);
         func(event);
         list_for_each_entry(child, &event->child_list, child_list)
                 func(child);
         mutex_unlock(&event->child_mutex);
 }
 
 static void perf_event_for_each(struct perf_event *event,
                                   void (*func)(struct perf_event *))
 {
         struct perf_event_context *ctx = event->ctx;
         struct perf_event *sibling;
 
         lockdep_assert_held(&ctx->mutex);
 
         event = event->group_leader;
 
         perf_event_for_each_child(event, func);
         for_each_sibling_event(sibling, event)
                 perf_event_for_each_child(sibling, func);
 }
 
 static void __perf_event_period(struct perf_event *event,
                                 struct perf_cpu_context *cpuctx,
                                 struct perf_event_context *ctx,
                                 void *info)
 {
         u64 value = *((u64 *)info);
         bool active;
 
         if (event->attr.freq) {
                 event->attr.sample_freq = value;
         } else {
                 event->attr.sample_period = value;
                 event->hw.sample_period = value;
         }
 
         active = (event->state == PERF_EVENT_STATE_ACTIVE);
         if (active) {
                 perf_pmu_disable(event->pmu);
                 /*
                  * We could be throttled; unthrottle now to avoid the tick
                  * trying to unthrottle while we already re-started the event.
                  */
                 if (event->hw.interrupts == MAX_INTERRUPTS) {
                         event->hw.interrupts = 0;
                         perf_log_throttle(event, 1);
                 }
                 event->pmu->stop(event, PERF_EF_UPDATE);
         }
 
         local64_set(&event->hw.period_left, 0);
 
         if (active) {
                 event->pmu->start(event, PERF_EF_RELOAD);
                 perf_pmu_enable(event->pmu);
         }
 }
 
 static int perf_event_check_period(struct perf_event *event, u64 value)
 {
         return event->pmu->check_period(event, value);
 }
 
 static int _perf_event_period(struct perf_event *event, u64 value)
 {
         if (!is_sampling_event(event))
                 return -EINVAL;
 
         if (!value)
                 return -EINVAL;
 
         if (event->attr.freq && value > sysctl_perf_event_sample_rate)
                 return -EINVAL;
 
         if (perf_event_check_period(event, value))
                 return -EINVAL;
 
         if (!event->attr.freq && (value & (1ULL << 63)))
                 return -EINVAL;
 
         event_function_call(event, __perf_event_period, &value);
 
         return 0;
 }
 
 int perf_event_period(struct perf_event *event, u64 value)
 {
         struct perf_event_context *ctx;
         int ret;
 
         ctx = perf_event_ctx_lock(event);
         ret = _perf_event_period(event, value);
         perf_event_ctx_unlock(event, ctx);
 
         return ret;
 }
 EXPORT_SYMBOL_GPL(perf_event_period);
 
 static const struct file_operations perf_fops;
 
 static inline int perf_fget_light(int fd, struct fd *p)
 {
         struct fd f = fdget(fd);
         if (!f.file)
                 return -EBADF;
 
         if (f.file->f_op != &perf_fops) {
                 fdput(f);
                 return -EBADF;
         }
         *p = f;
         return 0;
 }
 
 static int perf_event_set_output(struct perf_event *event,
                                  struct perf_event *output_event);
 static int perf_event_set_filter(struct perf_event *event, void __user *arg);
 static int perf_copy_attr(struct perf_event_attr __user *uattr,
                           struct perf_event_attr *attr);
 
 static long _perf_ioctl(struct perf_event *event, unsigned int cmd, unsigned long arg)
 {
         void (*func)(struct perf_event *);
         u32 flags = arg;
 
         switch (cmd) {
         case PERF_EVENT_IOC_ENABLE:
                 func = _perf_event_enable;
                 break;
         case PERF_EVENT_IOC_DISABLE:
                 func = _perf_event_disable;
                 break;
         case PERF_EVENT_IOC_RESET:
                 func = _perf_event_reset;
                 break;
 
         case PERF_EVENT_IOC_REFRESH:
                 return _perf_event_refresh(event, arg);
 
         case PERF_EVENT_IOC_PERIOD:
         {
                 u64 value;
 
                 if (copy_from_user(&value, (u64 __user *)arg, sizeof(value)))
                         return -EFAULT;
 
                 return _perf_event_period(event, value);
         }
         case PERF_EVENT_IOC_ID:
         {
                 u64 id = primary_event_id(event);
 
                 if (copy_to_user((void __user *)arg, &id, sizeof(id)))
                         return -EFAULT;
                 return 0;
         }
 
         case PERF_EVENT_IOC_SET_OUTPUT:
         {
                 int ret;
                 if (arg != -1) {
                         struct perf_event *output_event;
                         struct fd output;
                         ret = perf_fget_light(arg, &output);
                         if (ret)
                                 return ret;
                         output_event = output.file->private_data;
                         ret = perf_event_set_output(event, output_event);
                         fdput(output);
                 } else {
                         ret = perf_event_set_output(event, NULL);
                 }
                 return ret;
         }
 
         case PERF_EVENT_IOC_SET_FILTER:
                 return perf_event_set_filter(event, (void __user *)arg);
 
         case PERF_EVENT_IOC_SET_BPF:
         {
                 struct bpf_prog *prog;
                 int err;
 
                 prog = bpf_prog_get(arg);
                 if (IS_ERR(prog))
                         return PTR_ERR(prog);
 
                 err = perf_event_set_bpf_prog(event, prog, 0);
                 if (err) {
                         bpf_prog_put(prog);
                         return err;
                 }
 
                 return 0;
         }
 
         case PERF_EVENT_IOC_PAUSE_OUTPUT: {
                 struct perf_buffer *rb;
 
                 rcu_read_lock();
                 rb = rcu_dereference(event->rb);
                 if (!rb || !rb->nr_pages) {
                         rcu_read_unlock();
                         return -EINVAL;
                 }
                 rb_toggle_paused(rb, !!arg);
                 rcu_read_unlock();
                 return 0;
         }
 
         case PERF_EVENT_IOC_QUERY_BPF:
                 return perf_event_query_prog_array(event, (void __user *)arg);
 
         case PERF_EVENT_IOC_MODIFY_ATTRIBUTES: {
                 struct perf_event_attr new_attr;
                 int err = perf_copy_attr((struct perf_event_attr __user *)arg,
                                          &new_attr);
 
                 if (err)
                         return err;
 
                 return perf_event_modify_attr(event,  &new_attr);
         }
         default:
                 return -ENOTTY;
         }
 
         if (flags & PERF_IOC_FLAG_GROUP)
                 perf_event_for_each(event, func);
         else
                 perf_event_for_each_child(event, func);
 
         return 0;
 }
 
 static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
         struct perf_event *event = file->private_data;
         struct perf_event_context *ctx;
         long ret;
 
         /* Treat ioctl like writes as it is likely a mutating operation. */
         ret = security_perf_event_write(event);
         if (ret)
                 return ret;
 
         ctx = perf_event_ctx_lock(event);
         ret = _perf_ioctl(event, cmd, arg);
         perf_event_ctx_unlock(event, ctx);
 
         return ret;
 }
 
 #ifdef CONFIG_COMPAT
 static long perf_compat_ioctl(struct file *file, unsigned int cmd,
                                 unsigned long arg)
 {
         switch (_IOC_NR(cmd)) {
         case _IOC_NR(PERF_EVENT_IOC_SET_FILTER):
         case _IOC_NR(PERF_EVENT_IOC_ID):
         case _IOC_NR(PERF_EVENT_IOC_QUERY_BPF):
         case _IOC_NR(PERF_EVENT_IOC_MODIFY_ATTRIBUTES):
                 /* Fix up pointer size (usually 4 -> 8 in 32-on-64-bit case */
                 if (_IOC_SIZE(cmd) == sizeof(compat_uptr_t)) {
                         cmd &= ~IOCSIZE_MASK;
                         cmd |= sizeof(void *) << IOCSIZE_SHIFT;
                 }
                 break;
         }
         return perf_ioctl(file, cmd, arg);
 }
 #else
 # define perf_compat_ioctl NULL
 #endif
 
 int perf_event_task_enable(void)
 {
         struct perf_event_context *ctx;
         struct perf_event *event;
 
         mutex_lock(&current->perf_event_mutex);
         list_for_each_entry(event, &current->perf_event_list, owner_entry) {
                 ctx = perf_event_ctx_lock(event);
                 perf_event_for_each_child(event, _perf_event_enable);
                 perf_event_ctx_unlock(event, ctx);
         }
         mutex_unlock(&current->perf_event_mutex);
 
         return 0;
 }
 
 int perf_event_task_disable(void)
 {
         struct perf_event_context *ctx;
         struct perf_event *event;
 
         mutex_lock(&current->perf_event_mutex);
         list_for_each_entry(event, &current->perf_event_list, owner_entry) {
                 ctx = perf_event_ctx_lock(event);
                 perf_event_for_each_child(event, _perf_event_disable);
                 perf_event_ctx_unlock(event, ctx);
         }
         mutex_unlock(&current->perf_event_mutex);
 
         return 0;
 }
 
 static int perf_event_index(struct perf_event *event)
 {
         if (event->hw.state & PERF_HES_STOPPED)
                 return 0;
 
         if (event->state != PERF_EVENT_STATE_ACTIVE)
                 return 0;
 
         return event->pmu->event_idx(event);
 }
 
 static void perf_event_init_userpage(struct perf_event *event)
 {
         struct perf_event_mmap_page *userpg;
         struct perf_buffer *rb;
 
         rcu_read_lock();
         rb = rcu_dereference(event->rb);
         if (!rb)
                 goto unlock;
 
         userpg = rb->user_page;
 
         /* Allow new userspace to detect that bit 0 is deprecated */
         userpg->cap_bit0_is_deprecated = 1;
         userpg->size = offsetof(struct perf_event_mmap_page, __reserved);
         userpg->data_offset = PAGE_SIZE;
         userpg->data_size = perf_data_size(rb);
 
 unlock:
         rcu_read_unlock();
 }
 
 void __weak arch_perf_update_userpage(
         struct perf_event *event, struct perf_event_mmap_page *userpg, u64 now)
 {
 }
 
 /*
  * Callers need to ensure there can be no nesting of this function, otherwise
  * the seqlock logic goes bad. We can not serialize this because the arch
  * code calls this from NMI context.
  */
 void perf_event_update_userpage(struct perf_event *event)
 {
         struct perf_event_mmap_page *userpg;
         struct perf_buffer *rb;
         u64 enabled, running, now;
 
         rcu_read_lock();
         rb = rcu_dereference(event->rb);
         if (!rb)
                 goto unlock;
 
         /*
          * compute total_time_enabled, total_time_running
          * based on snapshot values taken when the event
          * was last scheduled in.
          *
          * we cannot simply called update_context_time()
          * because of locking issue as we can be called in
          * NMI context
          */
         calc_timer_values(event, &now, &enabled, &running);
 
         userpg = rb->user_page;
         /*
          * Disable preemption to guarantee consistent time stamps are stored to
          * the user page.
          */
         preempt_disable();
         ++userpg->lock;
         barrier();
         userpg->index = perf_event_index(event);
         userpg->offset = perf_event_count(event);
         if (userpg->index)
                 userpg->offset -= local64_read(&event->hw.prev_count);
 
         userpg->time_enabled = enabled +
                         atomic64_read(&event->child_total_time_enabled);
 
         userpg->time_running = running +
                         atomic64_read(&event->child_total_time_running);
 
         arch_perf_update_userpage(event, userpg, now);
 
         barrier();
         ++userpg->lock;
         preempt_enable();
 unlock:
         rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(perf_event_update_userpage);
 
 static vm_fault_t perf_mmap_fault(struct vm_fault *vmf)
 {
         struct perf_event *event = vmf->vma->vm_file->private_data;
         struct perf_buffer *rb;
         vm_fault_t ret = VM_FAULT_SIGBUS;
 
         if (vmf->flags & FAULT_FLAG_MKWRITE) {
                 if (vmf->pgoff == 0)
                         ret = 0;
                 return ret;
         }
 
         rcu_read_lock();
         rb = rcu_dereference(event->rb);
         if (!rb)
                 goto unlock;
 
         if (vmf->pgoff && (vmf->flags & FAULT_FLAG_WRITE))
                 goto unlock;
 
         vmf->page = perf_mmap_to_page(rb, vmf->pgoff);
         if (!vmf->page)
                 goto unlock;
 
         get_page(vmf->page);
         vmf->page->mapping = vmf->vma->vm_file->f_mapping;
         vmf->page->index   = vmf->pgoff;
 
         ret = 0;
 unlock:
         rcu_read_unlock();
 
         return ret;
 }
 
 static void ring_buffer_attach(struct perf_event *event,
                                struct perf_buffer *rb)
 {
         struct perf_buffer *old_rb = NULL;
         unsigned long flags;
 
         WARN_ON_ONCE(event->parent);
 
         if (event->rb) {
                 /*
                  * Should be impossible, we set this when removing
                  * event->rb_entry and wait/clear when adding event->rb_entry.
                  */
                 WARN_ON_ONCE(event->rcu_pending);
 
                 old_rb = event->rb;
                 spin_lock_irqsave(&old_rb->event_lock, flags);
                 list_del_rcu(&event->rb_entry);
                 spin_unlock_irqrestore(&old_rb->event_lock, flags);
 
                 event->rcu_batches = get_state_synchronize_rcu();
                 event->rcu_pending = 1;
         }
 
         if (rb) {
                 if (event->rcu_pending) {
                         cond_synchronize_rcu(event->rcu_batches);
                         event->rcu_pending = 0;
                 }
 
                 spin_lock_irqsave(&rb->event_lock, flags);
                 list_add_rcu(&event->rb_entry, &rb->event_list);
                 spin_unlock_irqrestore(&rb->event_lock, flags);
         }
 
         /*
          * Avoid racing with perf_mmap_close(AUX): stop the event
          * before swizzling the event::rb pointer; if it's getting
          * unmapped, its aux_mmap_count will be 0 and it won't
          * restart. See the comment in __perf_pmu_output_stop().
          *
          * Data will inevitably be lost when set_output is done in
          * mid-air, but then again, whoever does it like this is
          * not in for the data anyway.
          */
         if (has_aux(event))
                 perf_event_stop(event, 0);
 
         rcu_assign_pointer(event->rb, rb);
 
         if (old_rb) {
                 ring_buffer_put(old_rb);
                 /*
                  * Since we detached before setting the new rb, so that we
                  * could attach the new rb, we could have missed a wakeup.
                  * Provide it now.
                  */
                 wake_up_all(&event->waitq);
         }
 }
 
 static void ring_buffer_wakeup(struct perf_event *event)
 {
         struct perf_buffer *rb;
 
         if (event->parent)
                 event = event->parent;
 
         rcu_read_lock();
         rb = rcu_dereference(event->rb);
         if (rb) {
                 list_for_each_entry_rcu(event, &rb->event_list, rb_entry)
                         wake_up_all(&event->waitq);
         }
         rcu_read_unlock();
 }
 
 struct perf_buffer *ring_buffer_get(struct perf_event *event)
 {
         struct perf_buffer *rb;
 
         if (event->parent)
                 event = event->parent;
 
         rcu_read_lock();
         rb = rcu_dereference(event->rb);
         if (rb) {
                 if (!refcount_inc_not_zero(&rb->refcount))
                         rb = NULL;
         }
         rcu_read_unlock();
 
         return rb;
 }
 
 void ring_buffer_put(struct perf_buffer *rb)
 {
         if (!refcount_dec_and_test(&rb->refcount))
                 return;
 
         WARN_ON_ONCE(!list_empty(&rb->event_list));
 
         call_rcu(&rb->rcu_head, rb_free_rcu);
 }
 
 static void perf_mmap_open(struct vm_area_struct *vma)
 {
         struct perf_event *event = vma->vm_file->private_data;
 
         atomic_inc(&event->mmap_count);
         atomic_inc(&event->rb->mmap_count);
 
         if (vma->vm_pgoff)
                 atomic_inc(&event->rb->aux_mmap_count);
 
         if (event->pmu->event_mapped)
                 event->pmu->event_mapped(event, vma->vm_mm);
 }
 
 static void perf_pmu_output_stop(struct perf_event *event);
 
 /*
  * A buffer can be mmap()ed multiple times; either directly through the same
  * event, or through other events by use of perf_event_set_output().
  *
  * In order to undo the VM accounting done by perf_mmap() we need to destroy
  * the buffer here, where we still have a VM context. This means we need
  * to detach all events redirecting to us.
  */
 static void perf_mmap_close(struct vm_area_struct *vma)
 {
         struct perf_event *event = vma->vm_file->private_data;
         struct perf_buffer *rb = ring_buffer_get(event);
         struct user_struct *mmap_user = rb->mmap_user;
         int mmap_locked = rb->mmap_locked;
         unsigned long size = perf_data_size(rb);
         bool detach_rest = false;
 
         if (event->pmu->event_unmapped)
                 event->pmu->event_unmapped(event, vma->vm_mm);
 
         /*
          * The AUX buffer is strictly a sub-buffer, serialize using aux_mutex
          * to avoid complications.
          */
         if (rb_has_aux(rb) && vma->vm_pgoff == rb->aux_pgoff &&
             atomic_dec_and_mutex_lock(&rb->aux_mmap_count, &rb->aux_mutex)) {
                 /*
                  * Stop all AUX events that are writing to this buffer,
                  * so that we can free its AUX pages and corresponding PMU
                  * data. Note that after rb::aux_mmap_count dropped to zero,
                  * they won't start any more (see perf_aux_output_begin()).
                  */
                 perf_pmu_output_stop(event);
 
                 /* now it's safe to free the pages */
                 atomic_long_sub(rb->aux_nr_pages - rb->aux_mmap_locked, &mmap_user->locked_vm);
                 atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm);
 
                 /* this has to be the last one */
                 rb_free_aux(rb);
                 WARN_ON_ONCE(refcount_read(&rb->aux_refcount));
 
                 mutex_unlock(&rb->aux_mutex);
         }
 
         if (atomic_dec_and_test(&rb->mmap_count))
                 detach_rest = true;
 
         if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex))
                 goto out_put;
 
         ring_buffer_attach(event, NULL);
         mutex_unlock(&event->mmap_mutex);
 
         /* If there's still other mmap()s of this buffer, we're done. */
         if (!detach_rest)
                 goto out_put;
 
         /*
          * No other mmap()s, detach from all other events that might redirect
          * into the now unreachable buffer. Somewhat complicated by the
          * fact that rb::event_lock otherwise nests inside mmap_mutex.
          */
 again:
         rcu_read_lock();
         list_for_each_entry_rcu(event, &rb->event_list, rb_entry) {
                 if (!atomic_long_inc_not_zero(&event->refcount)) {
                         /*
                          * This event is en-route to free_event() which will
                          * detach it and remove it from the list.
                          */
                         continue;
                 }
                 rcu_read_unlock();
 
                 mutex_lock(&event->mmap_mutex);
                 /*
                  * Check we didn't race with perf_event_set_output() which can
                  * swizzle the rb from under us while we were waiting to
                  * acquire mmap_mutex.
                  *
                  * If we find a different rb; ignore this event, a next
                  * iteration will no longer find it on the list. We have to
                  * still restart the iteration to make sure we're not now
                  * iterating the wrong list.
                  */
                 if (event->rb == rb)
                         ring_buffer_attach(event, NULL);
 
                 mutex_unlock(&event->mmap_mutex);
                 put_event(event);
 
                 /*
                  * Restart the iteration; either we're on the wrong list or
                  * destroyed its integrity by doing a deletion.
                  */
                 goto again;
         }
         rcu_read_unlock();
 
         /*
          * It could be there's still a few 0-ref events on the list; they'll
          * get cleaned up by free_event() -- they'll also still have their
          * ref on the rb and will free it whenever they are done with it.
          *
          * Aside from that, this buffer is 'fully' detached and unmapped,
          * undo the VM accounting.
          */
 
         atomic_long_sub((size >> PAGE_SHIFT) + 1 - mmap_locked,
                         &mmap_user->locked_vm);
         atomic64_sub(mmap_locked, &vma->vm_mm->pinned_vm);
         free_uid(mmap_user);
 
 out_put:
         ring_buffer_put(rb); /* could be last */
 }
 
 static const struct vm_operations_struct perf_mmap_vmops = {
         .open           = perf_mmap_open,
         .close          = perf_mmap_close, /* non mergeable */
         .fault          = perf_mmap_fault,
         .page_mkwrite   = perf_mmap_fault,
 };
 
 static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 {
         struct perf_event *event = file->private_data;
         unsigned long user_locked, user_lock_limit;
         struct user_struct *user = current_user();
         struct mutex *aux_mutex = NULL;
         struct perf_buffer *rb = NULL;
         unsigned long locked, lock_limit;
         unsigned long vma_size;
         unsigned long nr_pages;
         long user_extra = 0, extra = 0;
         int ret = 0, flags = 0;
 
         /*
          * Don't allow mmap() of inherited per-task counters. This would
          * create a performance issue due to all children writing to the
          * same rb.
          */
         if (event->cpu == -1 && event->attr.inherit)
                 return -EINVAL;
 
         if (!(vma->vm_flags & VM_SHARED))
                 return -EINVAL;
 
         ret = security_perf_event_read(event);
         if (ret)
                 return ret;
 
         vma_size = vma->vm_end - vma->vm_start;
 
         if (vma->vm_pgoff == 0) {
                 nr_pages = (vma_size / PAGE_SIZE) - 1;
         } else {
                 /*
                  * AUX area mapping: if rb->aux_nr_pages != 0, it's already
                  * mapped, all subsequent mappings should have the same size
                  * and offset. Must be above the normal perf buffer.
                  */
                 u64 aux_offset, aux_size;
 
                 if (!event->rb)
                         return -EINVAL;
 
                 nr_pages = vma_size / PAGE_SIZE;
                 if (nr_pages > INT_MAX)
                         return -ENOMEM;
 
                 mutex_lock(&event->mmap_mutex);
                 ret = -EINVAL;
 
                 rb = event->rb;
                 if (!rb)
                         goto aux_unlock;
 
                 aux_mutex = &rb->aux_mutex;
                 mutex_lock(aux_mutex);
 
                 aux_offset = READ_ONCE(rb->user_page->aux_offset);
                 aux_size = READ_ONCE(rb->user_page->aux_size);
 
                 if (aux_offset < perf_data_size(rb) + PAGE_SIZE)
                         goto aux_unlock;
 
                 if (aux_offset != vma->vm_pgoff << PAGE_SHIFT)
                         goto aux_unlock;
 
                 /* already mapped with a different offset */
                 if (rb_has_aux(rb) && rb->aux_pgoff != vma->vm_pgoff)
                         goto aux_unlock;
 
                 if (aux_size != vma_size || aux_size != nr_pages * PAGE_SIZE)
                         goto aux_unlock;
 
                 /* already mapped with a different size */
                 if (rb_has_aux(rb) && rb->aux_nr_pages != nr_pages)
                         goto aux_unlock;
 
                 if (!is_power_of_2(nr_pages))
                         goto aux_unlock;
 
                 if (!atomic_inc_not_zero(&rb->mmap_count))
                         goto aux_unlock;
 
                 if (rb_has_aux(rb)) {
                         atomic_inc(&rb->aux_mmap_count);
                         ret = 0;
                         goto unlock;
                 }
 
                 atomic_set(&rb->aux_mmap_count, 1);
                 user_extra = nr_pages;
 
                 goto accounting;
         }
 
         /*
          * If we have rb pages ensure they're a power-of-two number, so we
          * can do bitmasks instead of modulo.
          */
         if (nr_pages != 0 && !is_power_of_2(nr_pages))
                 return -EINVAL;
 
         if (vma_size != PAGE_SIZE * (1 + nr_pages))
                 return -EINVAL;
 
         WARN_ON_ONCE(event->ctx->parent_ctx);
 again:
         mutex_lock(&event->mmap_mutex);
         if (event->rb) {
                 if (data_page_nr(event->rb) != nr_pages) {
                         ret = -EINVAL;
                         goto unlock;
                 }
 
                 if (!atomic_inc_not_zero(&event->rb->mmap_count)) {
                         /*
                          * Raced against perf_mmap_close(); remove the
                          * event and try again.
                          */
                         ring_buffer_attach(event, NULL);
                         mutex_unlock(&event->mmap_mutex);
                         goto again;
                 }
 
                 goto unlock;
         }
 
         user_extra = nr_pages + 1;
 
 accounting:
         user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);
 
         /*
          * Increase the limit linearly with more CPUs:
          */
         user_lock_limit *= num_online_cpus();
 
         user_locked = atomic_long_read(&user->locked_vm);
 
         /*
          * sysctl_perf_event_mlock may have changed, so that
          *     user->locked_vm > user_lock_limit
          */
         if (user_locked > user_lock_limit)
                 user_locked = user_lock_limit;
         user_locked += user_extra;
 
         if (user_locked > user_lock_limit) {
                 /*
                  * charge locked_vm until it hits user_lock_limit;
                  * charge the rest from pinned_vm
                  */
                 extra = user_locked - user_lock_limit;
                 user_extra -= extra;
         }
 
         lock_limit = rlimit(RLIMIT_MEMLOCK);
         lock_limit >>= PAGE_SHIFT;
         locked = atomic64_read(&vma->vm_mm->pinned_vm) + extra;
 
         if ((locked > lock_limit) && perf_is_paranoid() &&
                 !capable(CAP_IPC_LOCK)) {
                 ret = -EPERM;
                 goto unlock;
         }
 
         WARN_ON(!rb && event->rb);
 
         if (vma->vm_flags & VM_WRITE)
                 flags |= RING_BUFFER_WRITABLE;
 
         if (!rb) {
                 rb = rb_alloc(nr_pages,
                               event->attr.watermark ? event->attr.wakeup_watermark : 0,
                               event->cpu, flags);
 
                 if (!rb) {
                         ret = -ENOMEM;
                         goto unlock;
                 }
 
                 atomic_set(&rb->mmap_count, 1);
                 rb->mmap_user = get_current_user();
                 rb->mmap_locked = extra;
 
                 ring_buffer_attach(event, rb);
 
                 perf_event_update_time(event);
                 perf_event_init_userpage(event);
                 perf_event_update_userpage(event);
         } else {
                 ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
                                    event->attr.aux_watermark, flags);
                 if (!ret)
                         rb->aux_mmap_locked = extra;
         }
 
 unlock:
         if (!ret) {
                 atomic_long_add(user_extra, &user->locked_vm);
                 atomic64_add(extra, &vma->vm_mm->pinned_vm);
 
                 atomic_inc(&event->mmap_count);
         } else if (rb) {
                 atomic_dec(&rb->mmap_count);
         }
 aux_unlock:
         if (aux_mutex)
                 mutex_unlock(aux_mutex);
         mutex_unlock(&event->mmap_mutex);
 
         /*
          * Since pinned accounting is per vm we cannot allow fork() to copy our
          * vma.
          */
         vm_flags_set(vma, VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP);
         vma->vm_ops = &perf_mmap_vmops;
 
         if (event->pmu->event_mapped)
                 event->pmu->event_mapped(event, vma->vm_mm);
 
         return ret;
 }
 
 static int perf_fasync(int fd, struct file *filp, int on)
 {
         struct inode *inode = file_inode(filp);
         struct perf_event *event = filp->private_data;
         int retval;
 
         inode_lock(inode);
         retval = fasync_helper(fd, filp, on, &event->fasync);
         inode_unlock(inode);
 
         if (retval < 0)
                 return retval;
 
         return 0;
 }
 
 static const struct file_operations perf_fops = {
         .llseek                 = no_llseek,
         .release                = perf_release,
         .read                   = perf_read,
         .poll                   = perf_poll,
         .unlocked_ioctl         = perf_ioctl,
         .compat_ioctl           = perf_compat_ioctl,
         .mmap                   = perf_mmap,
         .fasync                 = perf_fasync,
 };
 
 /*
  * Perf event wakeup
  *
  * If there's data, ensure we set the poll() state and publish everything
  * to user-space before waking everybody up.
  */
 
 void perf_event_wakeup(struct perf_event *event)
 {
         ring_buffer_wakeup(event);
 
         if (event->pending_kill) {
                 kill_fasync(perf_event_fasync(event), SIGIO, event->pending_kill);
                 event->pending_kill = 0;
         }
 }
 
 static void perf_sigtrap(struct perf_event *event)
 {
         /*
          * We'd expect this to only occur if the irq_work is delayed and either
          * ctx->task or current has changed in the meantime. This can be the
          * case on architectures that do not implement arch_irq_work_raise().
          */
         if (WARN_ON_ONCE(event->ctx->task != current))
                 return;
 
         /*
          * Both perf_pending_task() and perf_pending_irq() can race with the
          * task exiting.
          */
         if (current->flags & PF_EXITING)
                 return;
 
         send_sig_perf((void __user *)event->pending_addr,
                       event->orig_type, event->attr.sig_data);
 }
 
 /*
  * Deliver the pending work in-event-context or follow the context.
  */
 static void __perf_pending_disable(struct perf_event *event)
 {
         int cpu = READ_ONCE(event->oncpu);
 
         /*
          * If the event isn't running; we done. event_sched_out() will have
          * taken care of things.
          */
         if (cpu < 0)
                 return;
 
         /*
          * Yay, we hit home and are in the context of the event.
          */
         if (cpu == smp_processor_id()) {
                 if (event->pending_disable) {
                         event->pending_disable = 0;
                         perf_event_disable_local(event);
                 }
                 return;
         }
 
         /*
          *  CPU-A                       CPU-B
          *
          *  perf_event_disable_inatomic()
          *    @pending_disable = CPU-A;
          *    irq_work_queue();
          *
          *  sched-out
          *    @pending_disable = -1;
          *
          *                              sched-in
          *                              perf_event_disable_inatomic()
          *                                @pending_disable = CPU-B;
          *                                irq_work_queue(); // FAILS
          *
          *  irq_work_run()
          *    perf_pending_disable()
          *
          * But the event runs on CPU-B and wants disabling there.
          */
         irq_work_queue_on(&event->pending_disable_irq, cpu);
 }
 
 static void perf_pending_disable(struct irq_work *entry)
 {
         struct perf_event *event = container_of(entry, struct perf_event, pending_disable_irq);
         int rctx;
 
         /*
          * If we 'fail' here, that's OK, it means recursion is already disabled
          * and we won't recurse 'further'.
          */
         rctx = perf_swevent_get_recursion_context();
         __perf_pending_disable(event);
         if (rctx >= 0)
                 perf_swevent_put_recursion_context(rctx);
 }
 
 static void perf_pending_irq(struct irq_work *entry)
 {
         struct perf_event *event = container_of(entry, struct perf_event, pending_irq);
         int rctx;
 
         /*
          * If we 'fail' here, that's OK, it means recursion is already disabled
          * and we won't recurse 'further'.
          */
         rctx = perf_swevent_get_recursion_context();
 
         /*
          * The wakeup isn't bound to the context of the event -- it can happen
          * irrespective of where the event is.
          */
         if (event->pending_wakeup) {
                 event->pending_wakeup = 0;
                 perf_event_wakeup(event);
         }
 
         if (rctx >= 0)
                 perf_swevent_put_recursion_context(rctx);
 }
 
 static void perf_pending_task(struct callback_head *head)
 {
         struct perf_event *event = container_of(head, struct perf_event, pending_task);
         int rctx;
 
         /*
          * All accesses to the event must belong to the same implicit RCU read-side
          * critical section as the ->pending_work reset. See comment in
          * perf_pending_task_sync().
          */
         rcu_read_lock();
         /*
          * If we 'fail' here, that's OK, it means recursion is already disabled
          * and we won't recurse 'further'.
          */
         rctx = perf_swevent_get_recursion_context();
 
         if (event->pending_work) {
                 event->pending_work = 0;
                 perf_sigtrap(event);
                 local_dec(&event->ctx->nr_pending);
                 rcuwait_wake_up(&event->pending_work_wait);
         }
         rcu_read_unlock();
 
         if (rctx >= 0)
                 perf_swevent_put_recursion_context(rctx);
 }
 
 #ifdef CONFIG_GUEST_PERF_EVENTS
 struct perf_guest_info_callbacks __rcu *perf_guest_cbs;
 
 DEFINE_STATIC_CALL_RET0(__perf_guest_state, *perf_guest_cbs->state);
 DEFINE_STATIC_CALL_RET0(__perf_guest_get_ip, *perf_guest_cbs->get_ip);
 DEFINE_STATIC_CALL_RET0(__perf_guest_handle_intel_pt_intr, *perf_guest_cbs->handle_intel_pt_intr);
 
 void perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
         if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs)))
                 return;
 
         rcu_assign_pointer(perf_guest_cbs, cbs);
         static_call_update(__perf_guest_state, cbs->state);
         static_call_update(__perf_guest_get_ip, cbs->get_ip);
 
         /* Implementing ->handle_intel_pt_intr is optional. */
         if (cbs->handle_intel_pt_intr)
                 static_call_update(__perf_guest_handle_intel_pt_intr,
                                    cbs->handle_intel_pt_intr);
 }
 EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
 
 void perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
 {
         if (WARN_ON_ONCE(rcu_access_pointer(perf_guest_cbs) != cbs))
                 return;
 
         rcu_assign_pointer(perf_guest_cbs, NULL);
         static_call_update(__perf_guest_state, (void *)&__static_call_return0);
         static_call_update(__perf_guest_get_ip, (void *)&__static_call_return0);
         static_call_update(__perf_guest_handle_intel_pt_intr,
                            (void *)&__static_call_return0);
         synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
 #endif
 
 static void
 perf_output_sample_regs(struct perf_output_handle *handle,
                         struct pt_regs *regs, u64 mask)
 {
         int bit;
         DECLARE_BITMAP(_mask, 64);
 
         bitmap_from_u64(_mask, mask);
         for_each_set_bit(bit, _mask, sizeof(mask) * BITS_PER_BYTE) {
                 u64 val;
 
                 val = perf_reg_value(regs, bit);
                 perf_output_put(handle, val);
         }
 }
 
 static void perf_sample_regs_user(struct perf_regs *regs_user,
                                   struct pt_regs *regs)
 {
         if (user_mode(regs)) {
                 regs_user->abi = perf_reg_abi(current);
                 regs_user->regs = regs;
         } else if (!(current->flags & PF_KTHREAD)) {
                 perf_get_regs_user(regs_user, regs);
         } else {
                 regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
                 regs_user->regs = NULL;
         }
 }
 
 static void perf_sample_regs_intr(struct perf_regs *regs_intr,
                                   struct pt_regs *regs)
 {
         regs_intr->regs = regs;
         regs_intr->abi  = perf_reg_abi(current);
 }
 
 
 /*
  * Get remaining task size from user stack pointer.
  *
  * It'd be better to take stack vma map and limit this more
  * precisely, but there's no way to get it safely under interrupt,
  * so using TASK_SIZE as limit.
  */
 static u64 perf_ustack_task_size(struct pt_regs *regs)
 {
         unsigned long addr = perf_user_stack_pointer(regs);
 
         if (!addr || addr >= TASK_SIZE)
                 return 0;
 
         return TASK_SIZE - addr;
 }
 
 static u16
 perf_sample_ustack_size(u16 stack_size, u16 header_size,
                         struct pt_regs *regs)
 {
         u64 task_size;
 
         /* No regs, no stack pointer, no dump. */
         if (!regs)
                 return 0;
 
         /*
          * Check if we fit in with the requested stack size into the:
          * - TASK_SIZE
          *   If we don't, we limit the size to the TASK_SIZE.
          *
          * - remaining sample size
          *   If we don't, we customize the stack size to
          *   fit in to the remaining sample size.
          */
 
         task_size  = min((u64) USHRT_MAX, perf_ustack_task_size(regs));
         stack_size = min(stack_size, (u16) task_size);
 
         /* Current header size plus static size and dynamic size. */
         header_size += 2 * sizeof(u64);
 
         /* Do we fit in with the current stack dump size? */
         if ((u16) (header_size + stack_size) < header_size) {
                 /*
                  * If we overflow the maximum size for the sample,
                  * we customize the stack dump size to fit in.
                  */
                 stack_size = USHRT_MAX - header_size - sizeof(u64);
                 stack_size = round_up(stack_size, sizeof(u64));
         }
 
         return stack_size;
 }
 
 static void
 perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size,
                           struct pt_regs *regs)
 {
         /* Case of a kernel thread, nothing to dump */
         if (!regs) {
                 u64 size = 0;
                 perf_output_put(handle, size);
         } else {
                 unsigned long sp;
                 unsigned int rem;
                 u64 dyn_size;
 
                 /*
                  * We dump:
                  * static size
                  *   - the size requested by user or the best one we can fit
                  *     in to the sample max size
                  * data
                  *   - user stack dump data
                  * dynamic size
                  *   - the actual dumped size
                  */
 
                 /* Static size. */
                 perf_output_put(handle, dump_size);
 
                 /* Data. */
                 sp = perf_user_stack_pointer(regs);
                 rem = __output_copy_user(handle, (void *) sp, dump_size);
                 dyn_size = dump_size - rem;
 
                 perf_output_skip(handle, rem);
 
                 /* Dynamic size. */
                 perf_output_put(handle, dyn_size);
         }
 }
 
 static unsigned long perf_prepare_sample_aux(struct perf_event *event,
                                           struct perf_sample_data *data,
                                           size_t size)
 {
         struct perf_event *sampler = event->aux_event;
         struct perf_buffer *rb;
 
         data->aux_size = 0;
 
         if (!sampler)
                 goto out;
 
         if (WARN_ON_ONCE(READ_ONCE(sampler->state) != PERF_EVENT_STATE_ACTIVE))
                 goto out;
 
         if (WARN_ON_ONCE(READ_ONCE(sampler->oncpu) != smp_processor_id()))
                 goto out;
 
         rb = ring_buffer_get(sampler);
         if (!rb)
                 goto out;
 
         /*
          * If this is an NMI hit inside sampling code, don't take
          * the sample. See also perf_aux_sample_output().
          */
         if (READ_ONCE(rb->aux_in_sampling)) {
                 data->aux_size = 0;
         } else {
                 size = min_t(size_t, size, perf_aux_size(rb));
                 data->aux_size = ALIGN(size, sizeof(u64));
         }
         ring_buffer_put(rb);
 
 out:
         return data->aux_size;
 }
 
 static long perf_pmu_snapshot_aux(struct perf_buffer *rb,
                                  struct perf_event *event,
                                  struct perf_output_handle *handle,
                                  unsigned long size)
 {
         unsigned long flags;
         long ret;
 
         /*
          * Normal ->start()/->stop() callbacks run in IRQ mode in scheduler
          * paths. If we start calling them in NMI context, they may race with
          * the IRQ ones, that is, for example, re-starting an event that's just
          * been stopped, which is why we're using a separate callback that
          * doesn't change the event state.
          *
          * IRQs need to be disabled to prevent IPIs from racing with us.
          */
         local_irq_save(flags);
         /*
          * Guard against NMI hits inside the critical section;
          * see also perf_prepare_sample_aux().
          */
         WRITE_ONCE(rb->aux_in_sampling, 1);
         barrier();
 
         ret = event->pmu->snapshot_aux(event, handle, size);
 
         barrier();
         WRITE_ONCE(rb->aux_in_sampling, 0);
         local_irq_restore(flags);
 
         return ret;
 }
 
 static void perf_aux_sample_output(struct perf_event *event,
                                    struct perf_output_handle *handle,
                                    struct perf_sample_data *data)
 {
         struct perf_event *sampler = event->aux_event;
         struct perf_buffer *rb;
         unsigned long pad;
         long size;
 
         if (WARN_ON_ONCE(!sampler || !data->aux_size))
                 return;
 
         rb = ring_buffer_get(sampler);
         if (!rb)
                 return;
 
         size = perf_pmu_snapshot_aux(rb, sampler, handle, data->aux_size);
 
         /*
          * An error here means that perf_output_copy() failed (returned a
          * non-zero surplus that it didn't copy), which in its current
          * enlightened implementation is not possible. If that changes, we'd
          * like to know.
          */
         if (WARN_ON_ONCE(size < 0))
                 goto out_put;
 
         /*
          * The pad comes from ALIGN()ing data->aux_size up to u64 in
          * perf_prepare_sample_aux(), so should not be more than that.
          */
         pad = data->aux_size - size;
         if (WARN_ON_ONCE(pad >= sizeof(u64)))
                 pad = 8;
 
         if (pad) {
                 u64 zero = 0;
                 perf_output_copy(handle, &zero, pad);
         }
 
 out_put:
         ring_buffer_put(rb);
 }
 
 /*
  * A set of common sample data types saved even for non-sample records
  * when event->attr.sample_id_all is set.
  */
 #define PERF_SAMPLE_ID_ALL  (PERF_SAMPLE_TID | PERF_SAMPLE_TIME |       \
                              PERF_SAMPLE_ID | PERF_SAMPLE_STREAM_ID |   \
                              PERF_SAMPLE_CPU | PERF_SAMPLE_IDENTIFIER)
 
 static void __perf_event_header__init_id(struct perf_sample_data *data,
                                          struct perf_event *event,
                                          u64 sample_type)
 {
         data->type = event->attr.sample_type;
         data->sample_flags |= data->type & PERF_SAMPLE_ID_ALL;
 
         if (sample_type & PERF_SAMPLE_TID) {
                 /* namespace issues */
                 data->tid_entry.pid = perf_event_pid(event, current);
                 data->tid_entry.tid = perf_event_tid(event, current);
         }
 
         if (sample_type & PERF_SAMPLE_TIME)
                 data->time = perf_event_clock(event);
 
         if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER))
                 data->id = primary_event_id(event);
 
         if (sample_type & PERF_SAMPLE_STREAM_ID)
                 data->stream_id = event->id;
 
         if (sample_type & PERF_SAMPLE_CPU) {
                 data->cpu_entry.cpu      = raw_smp_processor_id();
                 data->cpu_entry.reserved = 0;
         }
 }
 
 void perf_event_header__init_id(struct perf_event_header *header,
                                 struct perf_sample_data *data,
                                 struct perf_event *event)
 {
         if (event->attr.sample_id_all) {
                 header->size += event->id_header_size;
                 __perf_event_header__init_id(data, event, event->attr.sample_type);
         }
 }
 
 static void __perf_event__output_id_sample(struct perf_output_handle *handle,
                                            struct perf_sample_data *data)
 {
         u64 sample_type = data->type;
 
         if (sample_type & PERF_SAMPLE_TID)
                 perf_output_put(handle, data->tid_entry);
 
         if (sample_type & PERF_SAMPLE_TIME)
                 perf_output_put(handle, data->time);
 
         if (sample_type & PERF_SAMPLE_ID)
                 perf_output_put(handle, data->id);
 
         if (sample_type & PERF_SAMPLE_STREAM_ID)
                 perf_output_put(handle, data->stream_id);
 
         if (sample_type & PERF_SAMPLE_CPU)
                 perf_output_put(handle, data->cpu_entry);
 
         if (sample_type & PERF_SAMPLE_IDENTIFIER)
                 perf_output_put(handle, data->id);
 }
 
 void perf_event__output_id_sample(struct perf_event *event,
                                   struct perf_output_handle *handle,
                                   struct perf_sample_data *sample)
 {
         if (event->attr.sample_id_all)
                 __perf_event__output_id_sample(handle, sample);
 }
 
 static void perf_output_read_one(struct perf_output_handle *handle,
                                  struct perf_event *event,
                                  u64 enabled, u64 running)
 {
         u64 read_format = event->attr.read_format;
         u64 values[5];
         int n = 0;
 
         values[n++] = perf_event_count(event);
         if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
                 values[n++] = enabled +
                         atomic64_read(&event->child_total_time_enabled);
         }
         if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
                 values[n++] = running +
                         atomic64_read(&event->child_total_time_running);
         }
         if (read_format & PERF_FORMAT_ID)
                 values[n++] = primary_event_id(event);
         if (read_format & PERF_FORMAT_LOST)
                 values[n++] = atomic64_read(&event->lost_samples);
 
         __output_copy(handle, values, n * sizeof(u64));
 }
 
 static void perf_output_read_group(struct perf_output_handle *handle,
                             struct perf_event *event,
                             u64 enabled, u64 running)
 {
         struct perf_event *leader = event->group_leader, *sub;
         u64 read_format = event->attr.read_format;
         unsigned long flags;
         u64 values[6];
         int n = 0;
 
         /*
          * Disabling interrupts avoids all counter scheduling
          * (context switches, timer based rotation and IPIs).
          */
         local_irq_save(flags);
 
         values[n++] = 1 + leader->nr_siblings;
 
         if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
                 values[n++] = enabled;
 
         if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
                 values[n++] = running;
 
         if ((leader != event) &&
             (leader->state == PERF_EVENT_STATE_ACTIVE))
                 leader->pmu->read(leader);
 
         values[n++] = perf_event_count(leader);
         if (read_format & PERF_FORMAT_ID)
                 values[n++] = primary_event_id(leader);
         if (read_format & PERF_FORMAT_LOST)
                 values[n++] = atomic64_read(&leader->lost_samples);
 
         __output_copy(handle, values, n * sizeof(u64));
 
         for_each_sibling_event(sub, leader) {
                 n = 0;
 
                 if ((sub != event) &&
                     (sub->state == PERF_EVENT_STATE_ACTIVE))
                         sub->pmu->read(sub);
 
                 values[n++] = perf_event_count(sub);
                 if (read_format & PERF_FORMAT_ID)
                         values[n++] = primary_event_id(sub);
                 if (read_format & PERF_FORMAT_LOST)
                         values[n++] = atomic64_read(&sub->lost_samples);
 
                 __output_copy(handle, values, n * sizeof(u64));
         }
 
         local_irq_restore(flags);
 }
 
 #define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
                                  PERF_FORMAT_TOTAL_TIME_RUNNING)
 
 /*
  * XXX PERF_SAMPLE_READ vs inherited events seems difficult.
  *
  * The problem is that its both hard and excessively expensive to iterate the
  * child list, not to mention that its impossible to IPI the children running
  * on another CPU, from interrupt/NMI context.
  */
 static void perf_output_read(struct perf_output_handle *handle,
                              struct perf_event *event)
 {
         u64 enabled = 0, running = 0, now;
         u64 read_format = event->attr.read_format;
 
         /*
          * compute total_time_enabled, total_time_running
          * based on snapshot values taken when the event
          * was last scheduled in.
          *
          * we cannot simply called update_context_time()
          * because of locking issue as we are called in
          * NMI context
          */
         if (read_format & PERF_FORMAT_TOTAL_TIMES)
                 calc_timer_values(event, &now, &enabled, &running);
 
         if (event->attr.read_format & PERF_FORMAT_GROUP)
                 perf_output_read_group(handle, event, enabled, running);
         else
                 perf_output_read_one(handle, event, enabled, running);
 }
 
 void perf_output_sample(struct perf_output_handle *handle,
                         struct perf_event_header *header,
                         struct perf_sample_data *data,
                         struct perf_event *event)
 {
         u64 sample_type = data->type;
 
         perf_output_put(handle, *header);
 
         if (sample_type & PERF_SAMPLE_IDENTIFIER)
                 perf_output_put(handle, data->id);
 
         if (sample_type & PERF_SAMPLE_IP)
                 perf_output_put(handle, data->ip);
 
         if (sample_type & PERF_SAMPLE_TID)
                 perf_output_put(handle, data->tid_entry);
 
         if (sample_type & PERF_SAMPLE_TIME)
                 perf_output_put(handle, data->time);
 
         if (sample_type & PERF_SAMPLE_ADDR)
                 perf_output_put(handle, data->addr);
 
         if (sample_type & PERF_SAMPLE_ID)
                 perf_output_put(handle, data->id);
 
         if (sample_type & PERF_SAMPLE_STREAM_ID)
                 perf_output_put(handle, data->stream_id);
 
         if (sample_type & PERF_SAMPLE_CPU)
                 perf_output_put(handle, data->cpu_entry);
 
         if (sample_type & PERF_SAMPLE_PERIOD)
                 perf_output_put(handle, data->period);
 
         if (sample_type & PERF_SAMPLE_READ)
                 perf_output_read(handle, event);
 
         if (sample_type & PERF_SAMPLE_CALLCHAIN) {
                 int size = 1;
 
                 size += data->callchain->nr;
                 size *= sizeof(u64);
                 __output_copy(handle, data->callchain, size);
         }
 
         if (sample_type & PERF_SAMPLE_RAW) {
                 struct perf_raw_record *raw = data->raw;
 
                 if (raw) {
                         struct perf_raw_frag *frag = &raw->frag;
 
                         perf_output_put(handle, raw->size);
                         do {
                                 if (frag->copy) {
                                         __output_custom(handle, frag->copy,
                                                         frag->data, frag->size);
                                 } else {
                                         __output_copy(handle, frag->data,
                                                       frag->size);
                                 }
                                 if (perf_raw_frag_last(frag))
                                         break;
                                 frag = frag->next;
                         } while (1);
                         if (frag->pad)
                                 __output_skip(handle, NULL, frag->pad);
                 } else {
                         struct {
                                 u32     size;
                                 u32     data;
                         } raw = {
                                 .size = sizeof(u32),
                                 .data = 0,
                         };
                         perf_output_put(handle, raw);
                 }
         }
 
         if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
                 if (data->br_stack) {
                         size_t size;
 
                         size = data->br_stack->nr
                              * sizeof(struct perf_branch_entry);
 
                         perf_output_put(handle, data->br_stack->nr);
                         if (branch_sample_hw_index(event))
                                 perf_output_put(handle, data->br_stack->hw_idx);
                         perf_output_copy(handle, data->br_stack->entries, size);
                         /*
                          * Add the extension space which is appended
                          * right after the struct perf_branch_stack.
                          */
                         if (data->br_stack_cntr) {
                                 size = data->br_stack->nr * sizeof(u64);
                                 perf_output_copy(handle, data->br_stack_cntr, size);
                         }
                 } else {
                         /*
                          * we always store at least the value of nr
                          */
                         u64 nr = 0;
                         perf_output_put(handle, nr);
                 }
         }
 
         if (sample_type & PERF_SAMPLE_REGS_USER) {
                 u64 abi = data->regs_user.abi;
 
                 /*
                  * If there are no regs to dump, notice it through
                  * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
                  */
                 perf_output_put(handle, abi);
 
                 if (abi) {
                         u64 mask = event->attr.sample_regs_user;
                         perf_output_sample_regs(handle,
                                                 data->regs_user.regs,
                                                 mask);
                 }
         }
 
         if (sample_type & PERF_SAMPLE_STACK_USER) {
                 perf_output_sample_ustack(handle,
                                           data->stack_user_size,
                                           data->regs_user.regs);
         }
 
         if (sample_type & PERF_SAMPLE_WEIGHT_TYPE)
                 perf_output_put(handle, data->weight.full);
 
         if (sample_type & PERF_SAMPLE_DATA_SRC)
                 perf_output_put(handle, data->data_src.val);
 
         if (sample_type & PERF_SAMPLE_TRANSACTION)
                 perf_output_put(handle, data->txn);
 
         if (sample_type & PERF_SAMPLE_REGS_INTR) {
                 u64 abi = data->regs_intr.abi;
                 /*
                  * If there are no regs to dump, notice it through
                  * first u64 being zero (PERF_SAMPLE_REGS_ABI_NONE).
                  */
                 perf_output_put(handle, abi);
 
                 if (abi) {
                         u64 mask = event->attr.sample_regs_intr;
 
                         perf_output_sample_regs(handle,
                                                 data->regs_intr.regs,
                                                 mask);
                 }
         }
 
         if (sample_type & PERF_SAMPLE_PHYS_ADDR)
                 perf_output_put(handle, data->phys_addr);
 
         if (sample_type & PERF_SAMPLE_CGROUP)
                 perf_output_put(handle, data->cgroup);
 
         if (sample_type & PERF_SAMPLE_DATA_PAGE_SIZE)
                 perf_output_put(handle, data->data_page_size);
 
         if (sample_type & PERF_SAMPLE_CODE_PAGE_SIZE)
                 perf_output_put(handle, data->code_page_size);
 
         if (sample_type & PERF_SAMPLE_AUX) {
                 perf_output_put(handle, data->aux_size);
 
                 if (data->aux_size)
                         perf_aux_sample_output(event, handle, data);
         }
 
         if (!event->attr.watermark) {
                 int wakeup_events = event->attr.wakeup_events;
 
                 if (wakeup_events) {
                         struct perf_buffer *rb = handle->rb;
                         int events = local_inc_return(&rb->events);
 
                         if (events >= wakeup_events) {
                                 local_sub(wakeup_events, &rb->events);
                                 local_inc(&rb->wakeup);
                         }
                 }
         }
 }
 
 static u64 perf_virt_to_phys(u64 virt)
 {
         u64 phys_addr = 0;
 
         if (!virt)
                 return 0;
 
         if (virt >= TASK_SIZE) {
                 /* If it's vmalloc()d memory, leave phys_addr as 0 */
                 if (virt_addr_valid((void *)(uintptr_t)virt) &&
                     !(virt >= VMALLOC_START && virt < VMALLOC_END))
                         phys_addr = (u64)virt_to_phys((void *)(uintptr_t)virt);
         } else {
                 /*
                  * Walking the pages tables for user address.
                  * Interrupts are disabled, so it prevents any tear down
                  * of the page tables.
                  * Try IRQ-safe get_user_page_fast_only first.
                  * If failed, leave phys_addr as 0.
                  */
                 if (current->mm != NULL) {
                         struct page *p;
 
                         pagefault_disable();
                         if (get_user_page_fast_only(virt, 0, &p)) {
                                 phys_addr = page_to_phys(p) + virt % PAGE_SIZE;
                                 put_page(p);
                         }
                         pagefault_enable();
                 }
         }
 
         return phys_addr;
 }
 
 /*
  * Return the pagetable size of a given virtual address.
  */
 static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
 {
         u64 size = 0;
 
 #ifdef CONFIG_HAVE_GUP_FAST
         pgd_t *pgdp, pgd;
         p4d_t *p4dp, p4d;
         pud_t *pudp, pud;
         pmd_t *pmdp, pmd;
         pte_t *ptep, pte;
 
         pgdp = pgd_offset(mm, addr);
         pgd = READ_ONCE(*pgdp);
         if (pgd_none(pgd))
                 return 0;
 
         if (pgd_leaf(pgd))
                 return pgd_leaf_size(pgd);
 
         p4dp = p4d_offset_lockless(pgdp, pgd, addr);
         p4d = READ_ONCE(*p4dp);
         if (!p4d_present(p4d))
                 return 0;
 
         if (p4d_leaf(p4d))
                 return p4d_leaf_size(p4d);
 
         pudp = pud_offset_lockless(p4dp, p4d, addr);
         pud = READ_ONCE(*pudp);
         if (!pud_present(pud))
                 return 0;
 
         if (pud_leaf(pud))
                 return pud_leaf_size(pud);
 
         pmdp = pmd_offset_lockless(pudp, pud, addr);
 again:
         pmd = pmdp_get_lockless(pmdp);
         if (!pmd_present(pmd))
                 return 0;
 
         if (pmd_leaf(pmd))
                 return pmd_leaf_size(pmd);
 
         ptep = pte_offset_map(&pmd, addr);
         if (!ptep)
                 goto again;
 
         pte = ptep_get_lockless(ptep);
         if (pte_present(pte))
                 size = __pte_leaf_size(pmd, pte);
         pte_unmap(ptep);
 #endif /* CONFIG_HAVE_GUP_FAST */
 
         return size;
 }
 
 static u64 perf_get_page_size(unsigned long addr)
 {
         struct mm_struct *mm;
         unsigned long flags;
         u64 size;
 
         if (!addr)
                 return 0;
 
         /*
          * Software page-table walkers must disable IRQs,
          * which prevents any tear down of the page tables.
          */
         local_irq_save(flags);
 
         mm = current->mm;
         if (!mm) {
                 /*
                  * For kernel threads and the like, use init_mm so that
                  * we can find kernel memory.
                  */
                 mm = &init_mm;
         }
 
         size = perf_get_pgtable_size(mm, addr);
 
         local_irq_restore(flags);
 
         return size;
 }
 
 static struct perf_callchain_entry __empty_callchain = { .nr = 0, };
 
 struct perf_callchain_entry *
 perf_callchain(struct perf_event *event, struct pt_regs *regs)
 {
         bool kernel = !event->attr.exclude_callchain_kernel;
         bool user   = !event->attr.exclude_callchain_user;
         /* Disallow cross-task user callchains. */
         bool crosstask = event->ctx->task && event->ctx->task != current;
         const u32 max_stack = event->attr.sample_max_stack;
         struct perf_callchain_entry *callchain;
 
         if (!kernel && !user)
                 return &__empty_callchain;
 
         callchain = get_perf_callchain(regs, 0, kernel, user,
                                        max_stack, crosstask, true);
         return callchain ?: &__empty_callchain;
 }
 
 static __always_inline u64 __cond_set(u64 flags, u64 s, u64 d)
 {
         return d * !!(flags & s);
 }
 
 void perf_prepare_sample(struct perf_sample_data *data,
                          struct perf_event *event,
                          struct pt_regs *regs)
 {
         u64 sample_type = event->attr.sample_type;
         u64 filtered_sample_type;
 
         /*
          * Add the sample flags that are dependent to others.  And clear the
          * sample flags that have already been done by the PMU driver.
          */
         filtered_sample_type = sample_type;
         filtered_sample_type |= __cond_set(sample_type, PERF_SAMPLE_CODE_PAGE_SIZE,
                                            PERF_SAMPLE_IP);
         filtered_sample_type |= __cond_set(sample_type, PERF_SAMPLE_DATA_PAGE_SIZE |
                                            PERF_SAMPLE_PHYS_ADDR, PERF_SAMPLE_ADDR);
         filtered_sample_type |= __cond_set(sample_type, PERF_SAMPLE_STACK_USER,
                                            PERF_SAMPLE_REGS_USER);
         filtered_sample_type &= ~data->sample_flags;
 
         if (filtered_sample_type == 0) {
                 /* Make sure it has the correct data->type for output */
                 data->type = event->attr.sample_type;
                 return;
         }
 
         __perf_event_header__init_id(data, event, filtered_sample_type);
 
         if (filtered_sample_type & PERF_SAMPLE_IP) {
                 data->ip = perf_instruction_pointer(regs);
                 data->sample_flags |= PERF_SAMPLE_IP;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_CALLCHAIN)
                 perf_sample_save_callchain(data, event, regs);
 
         if (filtered_sample_type & PERF_SAMPLE_RAW) {
                 data->raw = NULL;
                 data->dyn_size += sizeof(u64);
                 data->sample_flags |= PERF_SAMPLE_RAW;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_BRANCH_STACK) {
                 data->br_stack = NULL;
                 data->dyn_size += sizeof(u64);
                 data->sample_flags |= PERF_SAMPLE_BRANCH_STACK;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_REGS_USER)
                 perf_sample_regs_user(&data->regs_user, regs);
 
         /*
          * It cannot use the filtered_sample_type here as REGS_USER can be set
          * by STACK_USER (using __cond_set() above) and we don't want to update
          * the dyn_size if it's not requested by users.
          */
         if ((sample_type & ~data->sample_flags) & PERF_SAMPLE_REGS_USER) {
                 /* regs dump ABI info */
                 int size = sizeof(u64);
 
                 if (data->regs_user.regs) {
                         u64 mask = event->attr.sample_regs_user;
                         size += hweight64(mask) * sizeof(u64);
                 }
 
                 data->dyn_size += size;
                 data->sample_flags |= PERF_SAMPLE_REGS_USER;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_STACK_USER) {
                 /*
                  * Either we need PERF_SAMPLE_STACK_USER bit to be always
                  * processed as the last one or have additional check added
                  * in case new sample type is added, because we could eat
                  * up the rest of the sample size.
                  */
                 u16 stack_size = event->attr.sample_stack_user;
                 u16 header_size = perf_sample_data_size(data, event);
                 u16 size = sizeof(u64);
 
                 stack_size = perf_sample_ustack_size(stack_size, header_size,
                                                      data->regs_user.regs);
 
                 /*
                  * If there is something to dump, add space for the dump
                  * itself and for the field that tells the dynamic size,
                  * which is how many have been actually dumped.
                  */
                 if (stack_size)
                         size += sizeof(u64) + stack_size;
 
                 data->stack_user_size = stack_size;
                 data->dyn_size += size;
                 data->sample_flags |= PERF_SAMPLE_STACK_USER;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_WEIGHT_TYPE) {
                 data->weight.full = 0;
                 data->sample_flags |= PERF_SAMPLE_WEIGHT_TYPE;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_DATA_SRC) {
                 data->data_src.val = PERF_MEM_NA;
                 data->sample_flags |= PERF_SAMPLE_DATA_SRC;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_TRANSACTION) {
                 data->txn = 0;
                 data->sample_flags |= PERF_SAMPLE_TRANSACTION;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_ADDR) {
                 data->addr = 0;
                 data->sample_flags |= PERF_SAMPLE_ADDR;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_REGS_INTR) {
                 /* regs dump ABI info */
                 int size = sizeof(u64);
 
                 perf_sample_regs_intr(&data->regs_intr, regs);
 
                 if (data->regs_intr.regs) {
                         u64 mask = event->attr.sample_regs_intr;
 
                         size += hweight64(mask) * sizeof(u64);
                 }
 
                 data->dyn_size += size;
                 data->sample_flags |= PERF_SAMPLE_REGS_INTR;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_PHYS_ADDR) {
                 data->phys_addr = perf_virt_to_phys(data->addr);
                 data->sample_flags |= PERF_SAMPLE_PHYS_ADDR;
         }
 
 #ifdef CONFIG_CGROUP_PERF
         if (filtered_sample_type & PERF_SAMPLE_CGROUP) {
                 struct cgroup *cgrp;
 
                 /* protected by RCU */
                 cgrp = task_css_check(current, perf_event_cgrp_id, 1)->cgroup;
                 data->cgroup = cgroup_id(cgrp);
                 data->sample_flags |= PERF_SAMPLE_CGROUP;
         }
 #endif
 
         /*
          * PERF_DATA_PAGE_SIZE requires PERF_SAMPLE_ADDR. If the user doesn't
          * require PERF_SAMPLE_ADDR, kernel implicitly retrieve the data->addr,
          * but the value will not dump to the userspace.
          */
         if (filtered_sample_type & PERF_SAMPLE_DATA_PAGE_SIZE) {
                 data->data_page_size = perf_get_page_size(data->addr);
                 data->sample_flags |= PERF_SAMPLE_DATA_PAGE_SIZE;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_CODE_PAGE_SIZE) {
                 data->code_page_size = perf_get_page_size(data->ip);
                 data->sample_flags |= PERF_SAMPLE_CODE_PAGE_SIZE;
         }
 
         if (filtered_sample_type & PERF_SAMPLE_AUX) {
                 u64 size;
                 u16 header_size = perf_sample_data_size(data, event);
 
                 header_size += sizeof(u64); /* size */
 
                 /*
                  * Given the 16bit nature of header::size, an AUX sample can
                  * easily overflow it, what with all the preceding sample bits.
                  * Make sure this doesn't happen by using up to U16_MAX bytes
                  * per sample in total (rounded down to 8 byte boundary).
                  */
                 size = min_t(size_t, U16_MAX - header_size,
                              event->attr.aux_sample_size);
                 size = rounddown(size, 8);
                 size = perf_prepare_sample_aux(event, data, size);
 
                 WARN_ON_ONCE(size + header_size > U16_MAX);
                 data->dyn_size += size + sizeof(u64); /* size above */
                 data->sample_flags |= PERF_SAMPLE_AUX;
         }
 }
 
 void perf_prepare_header(struct perf_event_header *header,
                          struct perf_sample_data *data,
                          struct perf_event *event,
                          struct pt_regs *regs)
 {
         header->type = PERF_RECORD_SAMPLE;
         header->size = perf_sample_data_size(data, event);
         header->misc = perf_misc_flags(regs);
 
         /*
          * If you're adding more sample types here, you likely need to do
          * something about the overflowing header::size, like repurpose the
          * lowest 3 bits of size, which should be always zero at the moment.
          * This raises a more important question, do we really need 512k sized
          * samples and why, so good argumentation is in order for whatever you
          * do here next.
          */
         WARN_ON_ONCE(header->size & 7);
 }
 
 static __always_inline int
 __perf_event_output(struct perf_event *event,
                     struct perf_sample_data *data,
                     struct pt_regs *regs,
                     int (*output_begin)(struct perf_output_handle *,
                                         struct perf_sample_data *,
                                         struct perf_event *,
                                         unsigned int))
 {
         struct perf_output_handle handle;
         struct perf_event_header header;
         int err;
 
         /* protect the callchain buffers */
         rcu_read_lock();
 
         perf_prepare_sample(data, event, regs);
         perf_prepare_header(&header, data, event, regs);
 
         err = output_begin(&handle, data, event, header.size);
         if (err)
                 goto exit;
 
         perf_output_sample(&handle, &header, data, event);
 
         perf_output_end(&handle);
 
 exit:
         rcu_read_unlock();
         return err;
 }
 
 void
 perf_event_output_forward(struct perf_event *event,
                          struct perf_sample_data *data,
                          struct pt_regs *regs)
 {
         __perf_event_output(event, data, regs, perf_output_begin_forward);
 }
 
 void
 perf_event_output_backward(struct perf_event *event,
                            struct perf_sample_data *data,
                            struct pt_regs *regs)
 {
         __perf_event_output(event, data, regs, perf_output_begin_backward);
 }
 
 int
 perf_event_output(struct perf_event *event,
                   struct perf_sample_data *data,
                   struct pt_regs *regs)
 {
         return __perf_event_output(event, data, regs, perf_output_begin);
 }
 
 /*
  * read event_id
  */
 
 struct perf_read_event {
         struct perf_event_header        header;
 
         u32                             pid;
         u32                             tid;
 };
 
 static void
 perf_event_read_event(struct perf_event *event,
                         struct task_struct *task)
 {
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         struct perf_read_event read_event = {
                 .header = {
                         .type = PERF_RECORD_READ,
                         .misc = 0,
                         .size = sizeof(read_event) + event->read_size,
                 },
                 .pid = perf_event_pid(event, task),
                 .tid = perf_event_tid(event, task),
         };
         int ret;
 
         perf_event_header__init_id(&read_event.header, &sample, event);
         ret = perf_output_begin(&handle, &sample, event, read_event.header.size);
         if (ret)
                 return;
 
         perf_output_put(&handle, read_event);
         perf_output_read(&handle, event);
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 
 typedef void (perf_iterate_f)(struct perf_event *event, void *data);
 
 static void
 perf_iterate_ctx(struct perf_event_context *ctx,
                    perf_iterate_f output,
                    void *data, bool all)
 {
         struct perf_event *event;
 
         list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
                 if (!all) {
                         if (event->state < PERF_EVENT_STATE_INACTIVE)
                                 continue;
                         if (!event_filter_match(event))
                                 continue;
                 }
 
                 output(event, data);
         }
 }
 
 static void perf_iterate_sb_cpu(perf_iterate_f output, void *data)
 {
         struct pmu_event_list *pel = this_cpu_ptr(&pmu_sb_events);
         struct perf_event *event;
 
         list_for_each_entry_rcu(event, &pel->list, sb_list) {
                 /*
                  * Skip events that are not fully formed yet; ensure that
                  * if we observe event->ctx, both event and ctx will be
                  * complete enough. See perf_install_in_context().
                  */
                 if (!smp_load_acquire(&event->ctx))
                         continue;
 
                 if (event->state < PERF_EVENT_STATE_INACTIVE)
                         continue;
                 if (!event_filter_match(event))
                         continue;
                 output(event, data);
         }
 }
 
 /*
  * Iterate all events that need to receive side-band events.
  *
  * For new callers; ensure that account_pmu_sb_event() includes
  * your event, otherwise it might not get delivered.
  */
 static void
 perf_iterate_sb(perf_iterate_f output, void *data,
                struct perf_event_context *task_ctx)
 {
         struct perf_event_context *ctx;
 
         rcu_read_lock();
         preempt_disable();
 
         /*
          * If we have task_ctx != NULL we only notify the task context itself.
          * The task_ctx is set only for EXIT events before releasing task
          * context.
          */
         if (task_ctx) {
                 perf_iterate_ctx(task_ctx, output, data, false);
                 goto done;
         }
 
         perf_iterate_sb_cpu(output, data);
 
         ctx = rcu_dereference(current->perf_event_ctxp);
         if (ctx)
                 perf_iterate_ctx(ctx, output, data, false);
 done:
         preempt_enable();
         rcu_read_unlock();
 }
 
 /*
  * Clear all file-based filters at exec, they'll have to be
  * re-instated when/if these objects are mmapped again.
  */
 static void perf_event_addr_filters_exec(struct perf_event *event, void *data)
 {
         struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
         struct perf_addr_filter *filter;
         unsigned int restart = 0, count = 0;
         unsigned long flags;
 
         if (!has_addr_filter(event))
                 return;
 
         raw_spin_lock_irqsave(&ifh->lock, flags);
         list_for_each_entry(filter, &ifh->list, entry) {
                 if (filter->path.dentry) {
                         event->addr_filter_ranges[count].start = 0;
                         event->addr_filter_ranges[count].size = 0;
                         restart++;
                 }
 
                 count++;
         }
 
         if (restart)
                 event->addr_filters_gen++;
         raw_spin_unlock_irqrestore(&ifh->lock, flags);
 
         if (restart)
                 perf_event_stop(event, 1);
 }
 
 void perf_event_exec(void)
 {
         struct perf_event_context *ctx;
 
         ctx = perf_pin_task_context(current);
         if (!ctx)
                 return;
 
         perf_event_enable_on_exec(ctx);
         perf_event_remove_on_exec(ctx);
         perf_iterate_ctx(ctx, perf_event_addr_filters_exec, NULL, true);
 
         perf_unpin_context(ctx);
         put_ctx(ctx);
 }
 
 struct remote_output {
         struct perf_buffer      *rb;
         int                     err;
 };
 
 static void __perf_event_output_stop(struct perf_event *event, void *data)
 {
         struct perf_event *parent = event->parent;
         struct remote_output *ro = data;
         struct perf_buffer *rb = ro->rb;
         struct stop_event_data sd = {
                 .event  = event,
         };
 
         if (!has_aux(event))
                 return;
 
         if (!parent)
                 parent = event;
 
         /*
          * In case of inheritance, it will be the parent that links to the
          * ring-buffer, but it will be the child that's actually using it.
          *
          * We are using event::rb to determine if the event should be stopped,
          * however this may race with ring_buffer_attach() (through set_output),
          * which will make us skip the event that actually needs to be stopped.
          * So ring_buffer_attach() has to stop an aux event before re-assigning
          * its rb pointer.
          */
         if (rcu_dereference(parent->rb) == rb)
                 ro->err = __perf_event_stop(&sd);
 }
 
 static int __perf_pmu_output_stop(void *info)
 {
         struct perf_event *event = info;
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct remote_output ro = {
                 .rb     = event->rb,
         };
 
         rcu_read_lock();
         perf_iterate_ctx(&cpuctx->ctx, __perf_event_output_stop, &ro, false);
         if (cpuctx->task_ctx)
                 perf_iterate_ctx(cpuctx->task_ctx, __perf_event_output_stop,
                                    &ro, false);
         rcu_read_unlock();
 
         return ro.err;
 }
 
 static void perf_pmu_output_stop(struct perf_event *event)
 {
         struct perf_event *iter;
         int err, cpu;
 
 restart:
         rcu_read_lock();
         list_for_each_entry_rcu(iter, &event->rb->event_list, rb_entry) {
                 /*
                  * For per-CPU events, we need to make sure that neither they
                  * nor their children are running; for cpu==-1 events it's
                  * sufficient to stop the event itself if it's active, since
                  * it can't have children.
                  */
                 cpu = iter->cpu;
                 if (cpu == -1)
                         cpu = READ_ONCE(iter->oncpu);
 
                 if (cpu == -1)
                         continue;
 
                 err = cpu_function_call(cpu, __perf_pmu_output_stop, event);
                 if (err == -EAGAIN) {
                         rcu_read_unlock();
                         goto restart;
                 }
         }
         rcu_read_unlock();
 }
 
 /*
  * task tracking -- fork/exit
  *
  * enabled by: attr.comm | attr.mmap | attr.mmap2 | attr.mmap_data | attr.task
  */
 
 struct perf_task_event {
         struct task_struct              *task;
         struct perf_event_context       *task_ctx;
 
         struct {
                 struct perf_event_header        header;
 
                 u32                             pid;
                 u32                             ppid;
                 u32                             tid;
                 u32                             ptid;
                 u64                             time;
         } event_id;
 };
 
 static int perf_event_task_match(struct perf_event *event)
 {
         return event->attr.comm  || event->attr.mmap ||
                event->attr.mmap2 || event->attr.mmap_data ||
                event->attr.task;
 }
 
 static void perf_event_task_output(struct perf_event *event,
                                    void *data)
 {
         struct perf_task_event *task_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         struct task_struct *task = task_event->task;
         int ret, size = task_event->event_id.header.size;
 
         if (!perf_event_task_match(event))
                 return;
 
         perf_event_header__init_id(&task_event->event_id.header, &sample, event);
 
         ret = perf_output_begin(&handle, &sample, event,
                                 task_event->event_id.header.size);
         if (ret)
                 goto out;
 
         task_event->event_id.pid = perf_event_pid(event, task);
         task_event->event_id.tid = perf_event_tid(event, task);
 
         if (task_event->event_id.header.type == PERF_RECORD_EXIT) {
                 task_event->event_id.ppid = perf_event_pid(event,
                                                         task->real_parent);
                 task_event->event_id.ptid = perf_event_pid(event,
                                                         task->real_parent);
         } else {  /* PERF_RECORD_FORK */
                 task_event->event_id.ppid = perf_event_pid(event, current);
                 task_event->event_id.ptid = perf_event_tid(event, current);
         }
 
         task_event->event_id.time = perf_event_clock(event);
 
         perf_output_put(&handle, task_event->event_id);
 
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 out:
         task_event->event_id.header.size = size;
 }
 
 static void perf_event_task(struct task_struct *task,
                               struct perf_event_context *task_ctx,
                               int new)
 {
         struct perf_task_event task_event;
 
         if (!atomic_read(&nr_comm_events) &&
             !atomic_read(&nr_mmap_events) &&
             !atomic_read(&nr_task_events))
                 return;
 
         task_event = (struct perf_task_event){
                 .task     = task,
                 .task_ctx = task_ctx,
                 .event_id    = {
                         .header = {
                                 .type = new ? PERF_RECORD_FORK : PERF_RECORD_EXIT,
                                 .misc = 0,
                                 .size = sizeof(task_event.event_id),
                         },
                         /* .pid  */
                         /* .ppid */
                         /* .tid  */
                         /* .ptid */
                         /* .time */
                 },
         };
 
         perf_iterate_sb(perf_event_task_output,
                        &task_event,
                        task_ctx);
 }
 
 void perf_event_fork(struct task_struct *task)
 {
         perf_event_task(task, NULL, 1);
         perf_event_namespaces(task);
 }
 
 /*
  * comm tracking
  */
 
 struct perf_comm_event {
         struct task_struct      *task;
         char                    *comm;
         int                     comm_size;
 
         struct {
                 struct perf_event_header        header;
 
                 u32                             pid;
                 u32                             tid;
         } event_id;
 };
 
 static int perf_event_comm_match(struct perf_event *event)
 {
         return event->attr.comm;
 }
 
 static void perf_event_comm_output(struct perf_event *event,
                                    void *data)
 {
         struct perf_comm_event *comm_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         int size = comm_event->event_id.header.size;
         int ret;
 
         if (!perf_event_comm_match(event))
                 return;
 
         perf_event_header__init_id(&comm_event->event_id.header, &sample, event);
         ret = perf_output_begin(&handle, &sample, event,
                                 comm_event->event_id.header.size);
 
         if (ret)
                 goto out;
 
         comm_event->event_id.pid = perf_event_pid(event, comm_event->task);
         comm_event->event_id.tid = perf_event_tid(event, comm_event->task);
 
         perf_output_put(&handle, comm_event->event_id);
         __output_copy(&handle, comm_event->comm,
                                    comm_event->comm_size);
 
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 out:
         comm_event->event_id.header.size = size;
 }
 
 static void perf_event_comm_event(struct perf_comm_event *comm_event)
 {
         char comm[TASK_COMM_LEN];
         unsigned int size;
 
         memset(comm, 0, sizeof(comm));
         strscpy(comm, comm_event->task->comm, sizeof(comm));
         size = ALIGN(strlen(comm)+1, sizeof(u64));
 
         comm_event->comm = comm;
         comm_event->comm_size = size;
 
         comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
 
         perf_iterate_sb(perf_event_comm_output,
                        comm_event,
                        NULL);
 }
 
 void perf_event_comm(struct task_struct *task, bool exec)
 {
         struct perf_comm_event comm_event;
 
         if (!atomic_read(&nr_comm_events))
                 return;
 
         comm_event = (struct perf_comm_event){
                 .task   = task,
                 /* .comm      */
                 /* .comm_size */
                 .event_id  = {
                         .header = {
                                 .type = PERF_RECORD_COMM,
                                 .misc = exec ? PERF_RECORD_MISC_COMM_EXEC : 0,
                                 /* .size */
                         },
                         /* .pid */
                         /* .tid */
                 },
         };
 
         perf_event_comm_event(&comm_event);
 }
 
 /*
  * namespaces tracking
  */
 
 struct perf_namespaces_event {
         struct task_struct              *task;
 
         struct {
                 struct perf_event_header        header;
 
                 u32                             pid;
                 u32                             tid;
                 u64                             nr_namespaces;
                 struct perf_ns_link_info        link_info[NR_NAMESPACES];
         } event_id;
 };
 
 static int perf_event_namespaces_match(struct perf_event *event)
 {
         return event->attr.namespaces;
 }
 
 static void perf_event_namespaces_output(struct perf_event *event,
                                          void *data)
 {
         struct perf_namespaces_event *namespaces_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         u16 header_size = namespaces_event->event_id.header.size;
         int ret;
 
         if (!perf_event_namespaces_match(event))
                 return;
 
         perf_event_header__init_id(&namespaces_event->event_id.header,
                                    &sample, event);
         ret = perf_output_begin(&handle, &sample, event,
                                 namespaces_event->event_id.header.size);
         if (ret)
                 goto out;
 
         namespaces_event->event_id.pid = perf_event_pid(event,
                                                         namespaces_event->task);
         namespaces_event->event_id.tid = perf_event_tid(event,
                                                         namespaces_event->task);
 
         perf_output_put(&handle, namespaces_event->event_id);
 
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 out:
         namespaces_event->event_id.header.size = header_size;
 }
 
 static void perf_fill_ns_link_info(struct perf_ns_link_info *ns_link_info,
                                    struct task_struct *task,
                                    const struct proc_ns_operations *ns_ops)
 {
         struct path ns_path;
         struct inode *ns_inode;
         int error;
 
         error = ns_get_path(&ns_path, task, ns_ops);
         if (!error) {
                 ns_inode = ns_path.dentry->d_inode;
                 ns_link_info->dev = new_encode_dev(ns_inode->i_sb->s_dev);
                 ns_link_info->ino = ns_inode->i_ino;
                 path_put(&ns_path);
         }
 }
 
 void perf_event_namespaces(struct task_struct *task)
 {
         struct perf_namespaces_event namespaces_event;
         struct perf_ns_link_info *ns_link_info;
 
         if (!atomic_read(&nr_namespaces_events))
                 return;
 
         namespaces_event = (struct perf_namespaces_event){
                 .task   = task,
                 .event_id  = {
                         .header = {
                                 .type = PERF_RECORD_NAMESPACES,
                                 .misc = 0,
                                 .size = sizeof(namespaces_event.event_id),
                         },
                         /* .pid */
                         /* .tid */
                         .nr_namespaces = NR_NAMESPACES,
                         /* .link_info[NR_NAMESPACES] */
                 },
         };
 
         ns_link_info = namespaces_event.event_id.link_info;
 
         perf_fill_ns_link_info(&ns_link_info[MNT_NS_INDEX],
                                task, &mntns_operations);
 
 #ifdef CONFIG_USER_NS
         perf_fill_ns_link_info(&ns_link_info[USER_NS_INDEX],
                                task, &userns_operations);
 #endif
 #ifdef CONFIG_NET_NS
         perf_fill_ns_link_info(&ns_link_info[NET_NS_INDEX],
                                task, &netns_operations);
 #endif
 #ifdef CONFIG_UTS_NS
         perf_fill_ns_link_info(&ns_link_info[UTS_NS_INDEX],
                                task, &utsns_operations);
 #endif
 #ifdef CONFIG_IPC_NS
         perf_fill_ns_link_info(&ns_link_info[IPC_NS_INDEX],
                                task, &ipcns_operations);
 #endif
 #ifdef CONFIG_PID_NS
         perf_fill_ns_link_info(&ns_link_info[PID_NS_INDEX],
                                task, &pidns_operations);
 #endif
 #ifdef CONFIG_CGROUPS
         perf_fill_ns_link_info(&ns_link_info[CGROUP_NS_INDEX],
                                task, &cgroupns_operations);
 #endif
 
         perf_iterate_sb(perf_event_namespaces_output,
                         &namespaces_event,
                         NULL);
 }
 
 /*
  * cgroup tracking
  */
 #ifdef CONFIG_CGROUP_PERF
 
 struct perf_cgroup_event {
         char                            *path;
         int                             path_size;
         struct {
                 struct perf_event_header        header;
                 u64                             id;
                 char                            path[];
         } event_id;
 };
 
 static int perf_event_cgroup_match(struct perf_event *event)
 {
         return event->attr.cgroup;
 }
 
 static void perf_event_cgroup_output(struct perf_event *event, void *data)
 {
         struct perf_cgroup_event *cgroup_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         u16 header_size = cgroup_event->event_id.header.size;
         int ret;
 
         if (!perf_event_cgroup_match(event))
                 return;
 
         perf_event_header__init_id(&cgroup_event->event_id.header,
                                    &sample, event);
         ret = perf_output_begin(&handle, &sample, event,
                                 cgroup_event->event_id.header.size);
         if (ret)
                 goto out;
 
         perf_output_put(&handle, cgroup_event->event_id);
         __output_copy(&handle, cgroup_event->path, cgroup_event->path_size);
 
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 out:
         cgroup_event->event_id.header.size = header_size;
 }
 
 static void perf_event_cgroup(struct cgroup *cgrp)
 {
         struct perf_cgroup_event cgroup_event;
         char path_enomem[16] = "//enomem";
         char *pathname;
         size_t size;
 
         if (!atomic_read(&nr_cgroup_events))
                 return;
 
         cgroup_event = (struct perf_cgroup_event){
                 .event_id  = {
                         .header = {
                                 .type = PERF_RECORD_CGROUP,
                                 .misc = 0,
                                 .size = sizeof(cgroup_event.event_id),
                         },
                         .id = cgroup_id(cgrp),
                 },
         };
 
         pathname = kmalloc(PATH_MAX, GFP_KERNEL);
         if (pathname == NULL) {
                 cgroup_event.path = path_enomem;
         } else {
                 /* just to be sure to have enough space for alignment */
                 cgroup_path(cgrp, pathname, PATH_MAX - sizeof(u64));
                 cgroup_event.path = pathname;
         }
 
         /*
          * Since our buffer works in 8 byte units we need to align our string
          * size to a multiple of 8. However, we must guarantee the tail end is
          * zero'd out to avoid leaking random bits to userspace.
          */
         size = strlen(cgroup_event.path) + 1;
         while (!IS_ALIGNED(size, sizeof(u64)))
                 cgroup_event.path[size++] = '\0';
 
         cgroup_event.event_id.header.size += size;
         cgroup_event.path_size = size;
 
         perf_iterate_sb(perf_event_cgroup_output,
                         &cgroup_event,
                         NULL);
 
         kfree(pathname);
 }
 
 #endif
 
 /*
  * mmap tracking
  */
 
 struct perf_mmap_event {
         struct vm_area_struct   *vma;
 
         const char              *file_name;
         int                     file_size;
         int                     maj, min;
         u64                     ino;
         u64                     ino_generation;
         u32                     prot, flags;
         u8                      build_id[BUILD_ID_SIZE_MAX];
         u32                     build_id_size;
 
         struct {
                 struct perf_event_header        header;
 
                 u32                             pid;
                 u32                             tid;
                 u64                             start;
                 u64                             len;
                 u64                             pgoff;
         } event_id;
 };
 
 static int perf_event_mmap_match(struct perf_event *event,
                                  void *data)
 {
         struct perf_mmap_event *mmap_event = data;
         struct vm_area_struct *vma = mmap_event->vma;
         int executable = vma->vm_flags & VM_EXEC;
 
         return (!executable && event->attr.mmap_data) ||
                (executable && (event->attr.mmap || event->attr.mmap2));
 }
 
 static void perf_event_mmap_output(struct perf_event *event,
                                    void *data)
 {
         struct perf_mmap_event *mmap_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         int size = mmap_event->event_id.header.size;
         u32 type = mmap_event->event_id.header.type;
         bool use_build_id;
         int ret;
 
         if (!perf_event_mmap_match(event, data))
                 return;
 
         if (event->attr.mmap2) {
                 mmap_event->event_id.header.type = PERF_RECORD_MMAP2;
                 mmap_event->event_id.header.size += sizeof(mmap_event->maj);
                 mmap_event->event_id.header.size += sizeof(mmap_event->min);
                 mmap_event->event_id.header.size += sizeof(mmap_event->ino);
                 mmap_event->event_id.header.size += sizeof(mmap_event->ino_generation);
                 mmap_event->event_id.header.size += sizeof(mmap_event->prot);
                 mmap_event->event_id.header.size += sizeof(mmap_event->flags);
         }
 
         perf_event_header__init_id(&mmap_event->event_id.header, &sample, event);
         ret = perf_output_begin(&handle, &sample, event,
                                 mmap_event->event_id.header.size);
         if (ret)
                 goto out;
 
         mmap_event->event_id.pid = perf_event_pid(event, current);
         mmap_event->event_id.tid = perf_event_tid(event, current);
 
         use_build_id = event->attr.build_id && mmap_event->build_id_size;
 
         if (event->attr.mmap2 && use_build_id)
                 mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID;
 
         perf_output_put(&handle, mmap_event->event_id);
 
         if (event->attr.mmap2) {
                 if (use_build_id) {
                         u8 size[4] = { (u8) mmap_event->build_id_size, 0, 0, 0 };
 
                         __output_copy(&handle, size, 4);
                         __output_copy(&handle, mmap_event->build_id, BUILD_ID_SIZE_MAX);
                 } else {
                         perf_output_put(&handle, mmap_event->maj);
                         perf_output_put(&handle, mmap_event->min);
                         perf_output_put(&handle, mmap_event->ino);
                         perf_output_put(&handle, mmap_event->ino_generation);
                 }
                 perf_output_put(&handle, mmap_event->prot);
                 perf_output_put(&handle, mmap_event->flags);
         }
 
         __output_copy(&handle, mmap_event->file_name,
                                    mmap_event->file_size);
 
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 out:
         mmap_event->event_id.header.size = size;
         mmap_event->event_id.header.type = type;
 }
 
 static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 {
         struct vm_area_struct *vma = mmap_event->vma;
         struct file *file = vma->vm_file;
         int maj = 0, min = 0;
         u64 ino = 0, gen = 0;
         u32 prot = 0, flags = 0;
         unsigned int size;
         char tmp[16];
         char *buf = NULL;
         char *name = NULL;
 
         if (vma->vm_flags & VM_READ)
                 prot |= PROT_READ;
         if (vma->vm_flags & VM_WRITE)
                 prot |= PROT_WRITE;
         if (vma->vm_flags & VM_EXEC)
                 prot |= PROT_EXEC;
 
         if (vma->vm_flags & VM_MAYSHARE)
                 flags = MAP_SHARED;
         else
                 flags = MAP_PRIVATE;
 
         if (vma->vm_flags & VM_LOCKED)
                 flags |= MAP_LOCKED;
         if (is_vm_hugetlb_page(vma))
                 flags |= MAP_HUGETLB;
 
         if (file) {
                 struct inode *inode;
                 dev_t dev;
 
                 buf = kmalloc(PATH_MAX, GFP_KERNEL);
                 if (!buf) {
                         name = "//enomem";
                         goto cpy_name;
                 }
                 /*
                  * d_path() works from the end of the rb backwards, so we
                  * need to add enough zero bytes after the string to handle
                  * the 64bit alignment we do later.
                  */
                 name = file_path(file, buf, PATH_MAX - sizeof(u64));
                 if (IS_ERR(name)) {
                         name = "//toolong";
                         goto cpy_name;
                 }
                 inode = file_inode(vma->vm_file);
                 dev = inode->i_sb->s_dev;
                 ino = inode->i_ino;
                 gen = inode->i_generation;
                 maj = MAJOR(dev);
                 min = MINOR(dev);
 
                 goto got_name;
         } else {
                 if (vma->vm_ops && vma->vm_ops->name)
                         name = (char *) vma->vm_ops->name(vma);
                 if (!name)
                         name = (char *)arch_vma_name(vma);
                 if (!name) {
                         if (vma_is_initial_heap(vma))
                                 name = "[heap]";
                         else if (vma_is_initial_stack(vma))
                                 name = "[stack]";
                         else
                                 name = "//anon";
                 }
         }
 
 cpy_name:
         strscpy(tmp, name, sizeof(tmp));
         name = tmp;
 got_name:
         /*
          * Since our buffer works in 8 byte units we need to align our string
          * size to a multiple of 8. However, we must guarantee the tail end is
          * zero'd out to avoid leaking random bits to userspace.
          */
         size = strlen(name)+1;
         while (!IS_ALIGNED(size, sizeof(u64)))
                 name[size++] = '\0';
 
         mmap_event->file_name = name;
         mmap_event->file_size = size;
         mmap_event->maj = maj;
         mmap_event->min = min;
         mmap_event->ino = ino;
         mmap_event->ino_generation = gen;
         mmap_event->prot = prot;
         mmap_event->flags = flags;
 
         if (!(vma->vm_flags & VM_EXEC))
                 mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_DATA;
 
         mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
 
         if (atomic_read(&nr_build_id_events))
                 build_id_parse(vma, mmap_event->build_id, &mmap_event->build_id_size);
 
         perf_iterate_sb(perf_event_mmap_output,
                        mmap_event,
                        NULL);
 
         kfree(buf);
 }
 
 /*
  * Check whether inode and address range match filter criteria.
  */
 static bool perf_addr_filter_match(struct perf_addr_filter *filter,
                                      struct file *file, unsigned long offset,
                                      unsigned long size)
 {
         /* d_inode(NULL) won't be equal to any mapped user-space file */
         if (!filter->path.dentry)
                 return false;
 
         if (d_inode(filter->path.dentry) != file_inode(file))
                 return false;
 
         if (filter->offset > offset + size)
                 return false;
 
         if (filter->offset + filter->size < offset)
                 return false;
 
         return true;
 }
 
 static bool perf_addr_filter_vma_adjust(struct perf_addr_filter *filter,
                                         struct vm_area_struct *vma,
                                         struct perf_addr_filter_range *fr)
 {
         unsigned long vma_size = vma->vm_end - vma->vm_start;
         unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
         struct file *file = vma->vm_file;
 
         if (!perf_addr_filter_match(filter, file, off, vma_size))
                 return false;
 
         if (filter->offset < off) {
                 fr->start = vma->vm_start;
                 fr->size = min(vma_size, filter->size - (off - filter->offset));
         } else {
                 fr->start = vma->vm_start + filter->offset - off;
                 fr->size = min(vma->vm_end - fr->start, filter->size);
         }
 
         return true;
 }
 
 static void __perf_addr_filters_adjust(struct perf_event *event, void *data)
 {
         struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
         struct vm_area_struct *vma = data;
         struct perf_addr_filter *filter;
         unsigned int restart = 0, count = 0;
         unsigned long flags;
 
         if (!has_addr_filter(event))
                 return;
 
         if (!vma->vm_file)
                 return;
 
         raw_spin_lock_irqsave(&ifh->lock, flags);
         list_for_each_entry(filter, &ifh->list, entry) {
                 if (perf_addr_filter_vma_adjust(filter, vma,
                                                 &event->addr_filter_ranges[count]))
                         restart++;
 
                 count++;
         }
 
         if (restart)
                 event->addr_filters_gen++;
         raw_spin_unlock_irqrestore(&ifh->lock, flags);
 
         if (restart)
                 perf_event_stop(event, 1);
 }
 
 /*
  * Adjust all task's events' filters to the new vma
  */
 static void perf_addr_filters_adjust(struct vm_area_struct *vma)
 {
         struct perf_event_context *ctx;
 
         /*
          * Data tracing isn't supported yet and as such there is no need
          * to keep track of anything that isn't related to executable code:
          */
         if (!(vma->vm_flags & VM_EXEC))
                 return;
 
         rcu_read_lock();
         ctx = rcu_dereference(current->perf_event_ctxp);
         if (ctx)
                 perf_iterate_ctx(ctx, __perf_addr_filters_adjust, vma, true);
         rcu_read_unlock();
 }
 
 void perf_event_mmap(struct vm_area_struct *vma)
 {
         struct perf_mmap_event mmap_event;
 
         if (!atomic_read(&nr_mmap_events))
                 return;
 
         mmap_event = (struct perf_mmap_event){
                 .vma    = vma,
                 /* .file_name */
                 /* .file_size */
                 .event_id  = {
                         .header = {
                                 .type = PERF_RECORD_MMAP,
                                 .misc = PERF_RECORD_MISC_USER,
                                 /* .size */
                         },
                         /* .pid */
                         /* .tid */
                         .start  = vma->vm_start,
                         .len    = vma->vm_end - vma->vm_start,
                         .pgoff  = (u64)vma->vm_pgoff << PAGE_SHIFT,
                 },
                 /* .maj (attr_mmap2 only) */
                 /* .min (attr_mmap2 only) */
                 /* .ino (attr_mmap2 only) */
                 /* .ino_generation (attr_mmap2 only) */
                 /* .prot (attr_mmap2 only) */
                 /* .flags (attr_mmap2 only) */
         };
 
         perf_addr_filters_adjust(vma);
         perf_event_mmap_event(&mmap_event);
 }
 
 void perf_event_aux_event(struct perf_event *event, unsigned long head,
                           unsigned long size, u64 flags)
 {
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         struct perf_aux_event {
                 struct perf_event_header        header;
                 u64                             offset;
                 u64                             size;
                 u64                             flags;
         } rec = {
                 .header = {
                         .type = PERF_RECORD_AUX,
                         .misc = 0,
                         .size = sizeof(rec),
                 },
                 .offset         = head,
                 .size           = size,
                 .flags          = flags,
         };
         int ret;
 
         perf_event_header__init_id(&rec.header, &sample, event);
         ret = perf_output_begin(&handle, &sample, event, rec.header.size);
 
         if (ret)
                 return;
 
         perf_output_put(&handle, rec);
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 
 /*
  * Lost/dropped samples logging
  */
 void perf_log_lost_samples(struct perf_event *event, u64 lost)
 {
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         int ret;
 
         struct {
                 struct perf_event_header        header;
                 u64                             lost;
         } lost_samples_event = {
                 .header = {
                         .type = PERF_RECORD_LOST_SAMPLES,
                         .misc = 0,
                         .size = sizeof(lost_samples_event),
                 },
                 .lost           = lost,
         };
 
         perf_event_header__init_id(&lost_samples_event.header, &sample, event);
 
         ret = perf_output_begin(&handle, &sample, event,
                                 lost_samples_event.header.size);
         if (ret)
                 return;
 
         perf_output_put(&handle, lost_samples_event);
         perf_event__output_id_sample(event, &handle, &sample);
         perf_output_end(&handle);
 }
 
 /*
  * context_switch tracking
  */
 
 struct perf_switch_event {
         struct task_struct      *task;
         struct task_struct      *next_prev;
 
         struct {
                 struct perf_event_header        header;
                 u32                             next_prev_pid;
                 u32                             next_prev_tid;
         } event_id;
 };
 
 static int perf_event_switch_match(struct perf_event *event)
 {
         return event->attr.context_switch;
 }
 
 static void perf_event_switch_output(struct perf_event *event, void *data)
 {
         struct perf_switch_event *se = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         int ret;
 
         if (!perf_event_switch_match(event))
                 return;
 
         /* Only CPU-wide events are allowed to see next/prev pid/tid */
         if (event->ctx->task) {
                 se->event_id.header.type = PERF_RECORD_SWITCH;
                 se->event_id.header.size = sizeof(se->event_id.header);
         } else {
                 se->event_id.header.type = PERF_RECORD_SWITCH_CPU_WIDE;
                 se->event_id.header.size = sizeof(se->event_id);
                 se->event_id.next_prev_pid =
                                         perf_event_pid(event, se->next_prev);
                 se->event_id.next_prev_tid =
                                         perf_event_tid(event, se->next_prev);
         }
 
         perf_event_header__init_id(&se->event_id.header, &sample, event);
 
         ret = perf_output_begin(&handle, &sample, event, se->event_id.header.size);
         if (ret)
                 return;
 
         if (event->ctx->task)
                 perf_output_put(&handle, se->event_id.header);
         else
                 perf_output_put(&handle, se->event_id);
 
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 
 static void perf_event_switch(struct task_struct *task,
                               struct task_struct *next_prev, bool sched_in)
 {
         struct perf_switch_event switch_event;
 
         /* N.B. caller checks nr_switch_events != 0 */
 
         switch_event = (struct perf_switch_event){
                 .task           = task,
                 .next_prev      = next_prev,
                 .event_id       = {
                         .header = {
                                 /* .type */
                                 .misc = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT,
                                 /* .size */
                         },
                         /* .next_prev_pid */
                         /* .next_prev_tid */
                 },
         };
 
         if (!sched_in && task->on_rq) {
                 switch_event.event_id.header.misc |=
                                 PERF_RECORD_MISC_SWITCH_OUT_PREEMPT;
         }
 
         perf_iterate_sb(perf_event_switch_output, &switch_event, NULL);
 }
 
 /*
  * IRQ throttle logging
  */
 
 static void perf_log_throttle(struct perf_event *event, int enable)
 {
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         int ret;
 
         struct {
                 struct perf_event_header        header;
                 u64                             time;
                 u64                             id;
                 u64                             stream_id;
         } throttle_event = {
                 .header = {
                         .type = PERF_RECORD_THROTTLE,
                         .misc = 0,
                         .size = sizeof(throttle_event),
                 },
                 .time           = perf_event_clock(event),
                 .id             = primary_event_id(event),
                 .stream_id      = event->id,
         };
 
         if (enable)
                 throttle_event.header.type = PERF_RECORD_UNTHROTTLE;
 
         perf_event_header__init_id(&throttle_event.header, &sample, event);
 
         ret = perf_output_begin(&handle, &sample, event,
                                 throttle_event.header.size);
         if (ret)
                 return;
 
         perf_output_put(&handle, throttle_event);
         perf_event__output_id_sample(event, &handle, &sample);
         perf_output_end(&handle);
 }
 
 /*
  * ksymbol register/unregister tracking
  */
 
 struct perf_ksymbol_event {
         const char      *name;
         int             name_len;
         struct {
                 struct perf_event_header        header;
                 u64                             addr;
                 u32                             len;
                 u16                             ksym_type;
                 u16                             flags;
         } event_id;
 };
 
 static int perf_event_ksymbol_match(struct perf_event *event)
 {
         return event->attr.ksymbol;
 }
 
 static void perf_event_ksymbol_output(struct perf_event *event, void *data)
 {
         struct perf_ksymbol_event *ksymbol_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         int ret;
 
         if (!perf_event_ksymbol_match(event))
                 return;
 
         perf_event_header__init_id(&ksymbol_event->event_id.header,
                                    &sample, event);
         ret = perf_output_begin(&handle, &sample, event,
                                 ksymbol_event->event_id.header.size);
         if (ret)
                 return;
 
         perf_output_put(&handle, ksymbol_event->event_id);
         __output_copy(&handle, ksymbol_event->name, ksymbol_event->name_len);
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 
 void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister,
                         const char *sym)
 {
         struct perf_ksymbol_event ksymbol_event;
         char name[KSYM_NAME_LEN];
         u16 flags = 0;
         int name_len;
 
         if (!atomic_read(&nr_ksymbol_events))
                 return;
 
         if (ksym_type >= PERF_RECORD_KSYMBOL_TYPE_MAX ||
             ksym_type == PERF_RECORD_KSYMBOL_TYPE_UNKNOWN)
                 goto err;
 
         strscpy(name, sym, KSYM_NAME_LEN);
         name_len = strlen(name) + 1;
         while (!IS_ALIGNED(name_len, sizeof(u64)))
                 name[name_len++] = '\0';
         BUILD_BUG_ON(KSYM_NAME_LEN % sizeof(u64));
 
         if (unregister)
                 flags |= PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER;
 
         ksymbol_event = (struct perf_ksymbol_event){
                 .name = name,
                 .name_len = name_len,
                 .event_id = {
                         .header = {
                                 .type = PERF_RECORD_KSYMBOL,
                                 .size = sizeof(ksymbol_event.event_id) +
                                         name_len,
                         },
                         .addr = addr,
                         .len = len,
                         .ksym_type = ksym_type,
                         .flags = flags,
                 },
         };
 
         perf_iterate_sb(perf_event_ksymbol_output, &ksymbol_event, NULL);
         return;
 err:
         WARN_ONCE(1, "%s: Invalid KSYMBOL type 0x%x\n", __func__, ksym_type);
 }
 
 /*
  * bpf program load/unload tracking
  */
 
 struct perf_bpf_event {
         struct bpf_prog *prog;
         struct {
                 struct perf_event_header        header;
                 u16                             type;
                 u16                             flags;
                 u32                             id;
                 u8                              tag[BPF_TAG_SIZE];
         } event_id;
 };
 
 static int perf_event_bpf_match(struct perf_event *event)
 {
         return event->attr.bpf_event;
 }
 
 static void perf_event_bpf_output(struct perf_event *event, void *data)
 {
         struct perf_bpf_event *bpf_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         int ret;
 
         if (!perf_event_bpf_match(event))
                 return;
 
         perf_event_header__init_id(&bpf_event->event_id.header,
                                    &sample, event);
         ret = perf_output_begin(&handle, &sample, event,
                                 bpf_event->event_id.header.size);
         if (ret)
                 return;
 
         perf_output_put(&handle, bpf_event->event_id);
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 
 static void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog,
                                          enum perf_bpf_event_type type)
 {
         bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD;
         int i;
 
         perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF,
                            (u64)(unsigned long)prog->bpf_func,
                            prog->jited_len, unregister,
                            prog->aux->ksym.name);
 
         for (i = 1; i < prog->aux->func_cnt; i++) {
                 struct bpf_prog *subprog = prog->aux->func[i];
 
                 perf_event_ksymbol(
                         PERF_RECORD_KSYMBOL_TYPE_BPF,
                         (u64)(unsigned long)subprog->bpf_func,
                         subprog->jited_len, unregister,
                         subprog->aux->ksym.name);
         }
 }
 
 void perf_event_bpf_event(struct bpf_prog *prog,
                           enum perf_bpf_event_type type,
                           u16 flags)
 {
         struct perf_bpf_event bpf_event;
 
         switch (type) {
         case PERF_BPF_EVENT_PROG_LOAD:
         case PERF_BPF_EVENT_PROG_UNLOAD:
                 if (atomic_read(&nr_ksymbol_events))
                         perf_event_bpf_emit_ksymbols(prog, type);
                 break;
         default:
                 return;
         }
 
         if (!atomic_read(&nr_bpf_events))
                 return;
 
         bpf_event = (struct perf_bpf_event){
                 .prog = prog,
                 .event_id = {
                         .header = {
                                 .type = PERF_RECORD_BPF_EVENT,
                                 .size = sizeof(bpf_event.event_id),
                         },
                         .type = type,
                         .flags = flags,
                         .id = prog->aux->id,
                 },
         };
 
         BUILD_BUG_ON(BPF_TAG_SIZE % sizeof(u64));
 
         memcpy(bpf_event.event_id.tag, prog->tag, BPF_TAG_SIZE);
         perf_iterate_sb(perf_event_bpf_output, &bpf_event, NULL);
 }
 
 struct perf_text_poke_event {
         const void              *old_bytes;
         const void              *new_bytes;
         size_t                  pad;
         u16                     old_len;
         u16                     new_len;
 
         struct {
                 struct perf_event_header        header;
 
                 u64                             addr;
         } event_id;
 };
 
 static int perf_event_text_poke_match(struct perf_event *event)
 {
         return event->attr.text_poke;
 }
 
 static void perf_event_text_poke_output(struct perf_event *event, void *data)
 {
         struct perf_text_poke_event *text_poke_event = data;
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         u64 padding = 0;
         int ret;
 
         if (!perf_event_text_poke_match(event))
                 return;
 
         perf_event_header__init_id(&text_poke_event->event_id.header, &sample, event);
 
         ret = perf_output_begin(&handle, &sample, event,
                                 text_poke_event->event_id.header.size);
         if (ret)
                 return;
 
         perf_output_put(&handle, text_poke_event->event_id);
         perf_output_put(&handle, text_poke_event->old_len);
         perf_output_put(&handle, text_poke_event->new_len);
 
         __output_copy(&handle, text_poke_event->old_bytes, text_poke_event->old_len);
         __output_copy(&handle, text_poke_event->new_bytes, text_poke_event->new_len);
 
         if (text_poke_event->pad)
                 __output_copy(&handle, &padding, text_poke_event->pad);
 
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 
 void perf_event_text_poke(const void *addr, const void *old_bytes,
                           size_t old_len, const void *new_bytes, size_t new_len)
 {
         struct perf_text_poke_event text_poke_event;
         size_t tot, pad;
 
         if (!atomic_read(&nr_text_poke_events))
                 return;
 
         tot  = sizeof(text_poke_event.old_len) + old_len;
         tot += sizeof(text_poke_event.new_len) + new_len;
         pad  = ALIGN(tot, sizeof(u64)) - tot;
 
         text_poke_event = (struct perf_text_poke_event){
                 .old_bytes    = old_bytes,
                 .new_bytes    = new_bytes,
                 .pad          = pad,
                 .old_len      = old_len,
                 .new_len      = new_len,
                 .event_id  = {
                         .header = {
                                 .type = PERF_RECORD_TEXT_POKE,
                                 .misc = PERF_RECORD_MISC_KERNEL,
                                 .size = sizeof(text_poke_event.event_id) + tot + pad,
                         },
                         .addr = (unsigned long)addr,
                 },
         };
 
         perf_iterate_sb(perf_event_text_poke_output, &text_poke_event, NULL);
 }
 
 void perf_event_itrace_started(struct perf_event *event)
 {
         event->attach_state |= PERF_ATTACH_ITRACE;
 }
 
 static void perf_log_itrace_start(struct perf_event *event)
 {
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         struct perf_aux_event {
                 struct perf_event_header        header;
                 u32                             pid;
                 u32                             tid;
         } rec;
         int ret;
 
         if (event->parent)
                 event = event->parent;
 
         if (!(event->pmu->capabilities & PERF_PMU_CAP_ITRACE) ||
             event->attach_state & PERF_ATTACH_ITRACE)
                 return;
 
         rec.header.type = PERF_RECORD_ITRACE_START;
         rec.header.misc = 0;
         rec.header.size = sizeof(rec);
         rec.pid = perf_event_pid(event, current);
         rec.tid = perf_event_tid(event, current);
 
         perf_event_header__init_id(&rec.header, &sample, event);
         ret = perf_output_begin(&handle, &sample, event, rec.header.size);
 
         if (ret)
                 return;
 
         perf_output_put(&handle, rec);
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 
 void perf_report_aux_output_id(struct perf_event *event, u64 hw_id)
 {
         struct perf_output_handle handle;
         struct perf_sample_data sample;
         struct perf_aux_event {
                 struct perf_event_header        header;
                 u64                             hw_id;
         } rec;
         int ret;
 
         if (event->parent)
                 event = event->parent;
 
         rec.header.type = PERF_RECORD_AUX_OUTPUT_HW_ID;
         rec.header.misc = 0;
         rec.header.size = sizeof(rec);
         rec.hw_id       = hw_id;
 
         perf_event_header__init_id(&rec.header, &sample, event);
         ret = perf_output_begin(&handle, &sample, event, rec.header.size);
 
         if (ret)
                 return;
 
         perf_output_put(&handle, rec);
         perf_event__output_id_sample(event, &handle, &sample);
 
         perf_output_end(&handle);
 }
 EXPORT_SYMBOL_GPL(perf_report_aux_output_id);
 
 static int
 __perf_event_account_interrupt(struct perf_event *event, int throttle)
 {
         struct hw_perf_event *hwc = &event->hw;
         int ret = 0;
         u64 seq;
 
         seq = __this_cpu_read(perf_throttled_seq);
         if (seq != hwc->interrupts_seq) {
                 hwc->interrupts_seq = seq;
                 hwc->interrupts = 1;
         } else {
                 hwc->interrupts++;
                 if (unlikely(throttle &&
                              hwc->interrupts > max_samples_per_tick)) {
                         __this_cpu_inc(perf_throttled_count);
                         tick_dep_set_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
                         hwc->interrupts = MAX_INTERRUPTS;
                         perf_log_throttle(event, 0);
                         ret = 1;
                 }
         }
 
         if (event->attr.freq) {
                 u64 now = perf_clock();
                 s64 delta = now - hwc->freq_time_stamp;
 
                 hwc->freq_time_stamp = now;
 
                 if (delta > 0 && delta < 2*TICK_NSEC)
                         perf_adjust_period(event, delta, hwc->last_period, true);
         }
 
         return ret;
 }
 
 int perf_event_account_interrupt(struct perf_event *event)
 {
         return __perf_event_account_interrupt(event, 1);
 }
 
 static inline bool sample_is_allowed(struct perf_event *event, struct pt_regs *regs)
 {
         /*
          * Due to interrupt latency (AKA "skid"), we may enter the
          * kernel before taking an overflow, even if the PMU is only
          * counting user events.
          */
         if (event->attr.exclude_kernel && !user_mode(regs))
                 return false;
 
         return true;
 }
 
 #ifdef CONFIG_BPF_SYSCALL
 static int bpf_overflow_handler(struct perf_event *event,
                                 struct perf_sample_data *data,
                                 struct pt_regs *regs)
 {
         struct bpf_perf_event_data_kern ctx = {
                 .data = data,
                 .event = event,
         };
         struct bpf_prog *prog;
         int ret = 0;
 
         ctx.regs = perf_arch_bpf_user_pt_regs(regs);
         if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1))
                 goto out;
         rcu_read_lock();
         prog = READ_ONCE(event->prog);
         if (prog) {
                 perf_prepare_sample(data, event, regs);
                 ret = bpf_prog_run(prog, &ctx);
         }
         rcu_read_unlock();
 out:
         __this_cpu_dec(bpf_prog_active);
 
         return ret;
 }
 
 static inline int perf_event_set_bpf_handler(struct perf_event *event,
                                              struct bpf_prog *prog,
                                              u64 bpf_cookie)
 {
         if (event->overflow_handler_context)
                 /* hw breakpoint or kernel counter */
                 return -EINVAL;
 
         if (event->prog)
                 return -EEXIST;
 
         if (prog->type != BPF_PROG_TYPE_PERF_EVENT)
                 return -EINVAL;
 
         if (event->attr.precise_ip &&
             prog->call_get_stack &&
             (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) ||
              event->attr.exclude_callchain_kernel ||
              event->attr.exclude_callchain_user)) {
                 /*
                  * On perf_event with precise_ip, calling bpf_get_stack()
                  * may trigger unwinder warnings and occasional crashes.
                  * bpf_get_[stack|stackid] works around this issue by using
                  * callchain attached to perf_sample_data. If the
                  * perf_event does not full (kernel and user) callchain
                  * attached to perf_sample_data, do not allow attaching BPF
                  * program that calls bpf_get_[stack|stackid].
                  */
                 return -EPROTO;
         }
 
         event->prog = prog;
         event->bpf_cookie = bpf_cookie;
         return 0;
 }
 
 static inline void perf_event_free_bpf_handler(struct perf_event *event)
 {
         struct bpf_prog *prog = event->prog;
 
         if (!prog)
                 return;
 
         event->prog = NULL;
         bpf_prog_put(prog);
 }
 #else
 static inline int bpf_overflow_handler(struct perf_event *event,
                                        struct perf_sample_data *data,
                                        struct pt_regs *regs)
 {
         return 1;
 }
 
 static inline int perf_event_set_bpf_handler(struct perf_event *event,
                                              struct bpf_prog *prog,
                                              u64 bpf_cookie)
 {
         return -EOPNOTSUPP;
 }
 
 static inline void perf_event_free_bpf_handler(struct perf_event *event)
 {
 }
 #endif
 
 /*
  * Generic event overflow handling, sampling.
  */
 
 static int __perf_event_overflow(struct perf_event *event,
                                  int throttle, struct perf_sample_data *data,
                                  struct pt_regs *regs)
 {
         int events = atomic_read(&event->event_limit);
         int ret = 0;
 
         /*
          * Non-sampling counters might still use the PMI to fold short
          * hardware counters, ignore those.
          */
         if (unlikely(!is_sampling_event(event)))
                 return 0;
 
         ret = __perf_event_account_interrupt(event, throttle);
 
         if (event->prog && event->prog->type == BPF_PROG_TYPE_PERF_EVENT &&
             !bpf_overflow_handler(event, data, regs))
                 return ret;
 
         /*
          * XXX event_limit might not quite work as expected on inherited
          * events
          */
 
         event->pending_kill = POLL_IN;
         if (events && atomic_dec_and_test(&event->event_limit)) {
                 ret = 1;
                 event->pending_kill = POLL_HUP;
                 perf_event_disable_inatomic(event);
         }
 
         if (event->attr.sigtrap) {
                 /*
                  * The desired behaviour of sigtrap vs invalid samples is a bit
                  * tricky; on the one hand, one should not loose the SIGTRAP if
                  * it is the first event, on the other hand, we should also not
                  * trigger the WARN or override the data address.
                  */
                 bool valid_sample = sample_is_allowed(event, regs);
                 unsigned int pending_id = 1;
                 enum task_work_notify_mode notify_mode;
 
                 if (regs)
                         pending_id = hash32_ptr((void *)instruction_pointer(regs)) ?: 1;
 
                 notify_mode = in_nmi() ? TWA_NMI_CURRENT : TWA_RESUME;
 
                 if (!event->pending_work &&
                     !task_work_add(current, &event->pending_task, notify_mode)) {
                         event->pending_work = pending_id;
                         local_inc(&event->ctx->nr_pending);
 
                         event->pending_addr = 0;
                         if (valid_sample && (data->sample_flags & PERF_SAMPLE_ADDR))
                                 event->pending_addr = data->addr;
 
                 } else if (event->attr.exclude_kernel && valid_sample) {
                         /*
                          * Should not be able to return to user space without
                          * consuming pending_work; with exceptions:
                          *
                          *  1. Where !exclude_kernel, events can overflow again
                          *     in the kernel without returning to user space.
                          *
                          *  2. Events that can overflow again before the IRQ-
                          *     work without user space progress (e.g. hrtimer).
                          *     To approximate progress (with false negatives),
                          *     check 32-bit hash of the current IP.
                          */
                         WARN_ON_ONCE(event->pending_work != pending_id);
                 }
         }
 
         READ_ONCE(event->overflow_handler)(event, data, regs);
 
         if (*perf_event_fasync(event) && event->pending_kill) {
                 event->pending_wakeup = 1;
                 irq_work_queue(&event->pending_irq);
         }
 
         return ret;
 }
 
 int perf_event_overflow(struct perf_event *event,
                         struct perf_sample_data *data,
                         struct pt_regs *regs)
 {
         return __perf_event_overflow(event, 1, data, regs);
 }
 
 /*
  * Generic software event infrastructure
  */
 
 struct swevent_htable {
         struct swevent_hlist            *swevent_hlist;
         struct mutex                    hlist_mutex;
         int                             hlist_refcount;
 };
 static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
 
 /*
  * We directly increment event->count and keep a second value in
  * event->hw.period_left to count intervals. This period event
  * is kept in the range [-sample_period, 0] so that we can use the
  * sign as trigger.
  */
 
 u64 perf_swevent_set_period(struct perf_event *event)
 {
         struct hw_perf_event *hwc = &event->hw;
         u64 period = hwc->last_period;
         u64 nr, offset;
         s64 old, val;
 
         hwc->last_period = hwc->sample_period;
 
         old = local64_read(&hwc->period_left);
         do {
                 val = old;
                 if (val < 0)
                         return 0;
 
                 nr = div64_u64(period + val, period);
                 offset = nr * period;
                 val -= offset;
         } while (!local64_try_cmpxchg(&hwc->period_left, &old, val));
 
         return nr;
 }
 
 static void perf_swevent_overflow(struct perf_event *event, u64 overflow,
                                     struct perf_sample_data *data,
                                     struct pt_regs *regs)
 {
         struct hw_perf_event *hwc = &event->hw;
         int throttle = 0;
 
         if (!overflow)
                 overflow = perf_swevent_set_period(event);
 
         if (hwc->interrupts == MAX_INTERRUPTS)
                 return;
 
         for (; overflow; overflow--) {
                 if (__perf_event_overflow(event, throttle,
                                             data, regs)) {
                         /*
                          * We inhibit the overflow from happening when
                          * hwc->interrupts == MAX_INTERRUPTS.
                          */
                         break;
                 }
                 throttle = 1;
         }
 }
 
 static void perf_swevent_event(struct perf_event *event, u64 nr,
                                struct perf_sample_data *data,
                                struct pt_regs *regs)
 {
         struct hw_perf_event *hwc = &event->hw;
 
         local64_add(nr, &event->count);
 
         if (!regs)
                 return;
 
         if (!is_sampling_event(event))
                 return;
 
         if ((event->attr.sample_type & PERF_SAMPLE_PERIOD) && !event->attr.freq) {
                 data->period = nr;
                 return perf_swevent_overflow(event, 1, data, regs);
         } else
                 data->period = event->hw.last_period;
 
         if (nr == 1 && hwc->sample_period == 1 && !event->attr.freq)
                 return perf_swevent_overflow(event, 1, data, regs);
 
         if (local64_add_negative(nr, &hwc->period_left))
                 return;
 
         perf_swevent_overflow(event, 0, data, regs);
 }
 
 static int perf_exclude_event(struct perf_event *event,
                               struct pt_regs *regs)
 {
         if (event->hw.state & PERF_HES_STOPPED)
                 return 1;
 
         if (regs) {
                 if (event->attr.exclude_user && user_mode(regs))
                         return 1;
 
                 if (event->attr.exclude_kernel && !user_mode(regs))
                         return 1;
         }
 
         return 0;
 }
 
 static int perf_swevent_match(struct perf_event *event,
                                 enum perf_type_id type,
                                 u32 event_id,
                                 struct perf_sample_data *data,
                                 struct pt_regs *regs)
 {
         if (event->attr.type != type)
                 return 0;
 
         if (event->attr.config != event_id)
                 return 0;
 
         if (perf_exclude_event(event, regs))
                 return 0;
 
         return 1;
 }
 
 static inline u64 swevent_hash(u64 type, u32 event_id)
 {
         u64 val = event_id | (type << 32);
 
         return hash_64(val, SWEVENT_HLIST_BITS);
 }
 
 static inline struct hlist_head *
 __find_swevent_head(struct swevent_hlist *hlist, u64 type, u32 event_id)
 {
         u64 hash = swevent_hash(type, event_id);
 
         return &hlist->heads[hash];
 }
 
 /* For the read side: events when they trigger */
 static inline struct hlist_head *
 find_swevent_head_rcu(struct swevent_htable *swhash, u64 type, u32 event_id)
 {
         struct swevent_hlist *hlist;
 
         hlist = rcu_dereference(swhash->swevent_hlist);
         if (!hlist)
                 return NULL;
 
         return __find_swevent_head(hlist, type, event_id);
 }
 
 /* For the event head insertion and removal in the hlist */
 static inline struct hlist_head *
 find_swevent_head(struct swevent_htable *swhash, struct perf_event *event)
 {
         struct swevent_hlist *hlist;
         u32 event_id = event->attr.config;
         u64 type = event->attr.type;
 
         /*
          * Event scheduling is always serialized against hlist allocation
          * and release. Which makes the protected version suitable here.
          * The context lock guarantees that.
          */
         hlist = rcu_dereference_protected(swhash->swevent_hlist,
                                           lockdep_is_held(&event->ctx->lock));
         if (!hlist)
                 return NULL;
 
         return __find_swevent_head(hlist, type, event_id);
 }
 
 static void do_perf_sw_event(enum perf_type_id type, u32 event_id,
                                     u64 nr,
                                     struct perf_sample_data *data,
                                     struct pt_regs *regs)
 {
         struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
         struct perf_event *event;
         struct hlist_head *head;
 
         rcu_read_lock();
         head = find_swevent_head_rcu(swhash, type, event_id);
         if (!head)
                 goto end;
 
         hlist_for_each_entry_rcu(event, head, hlist_entry) {
                 if (perf_swevent_match(event, type, event_id, data, regs))
                         perf_swevent_event(event, nr, data, regs);
         }
 end:
         rcu_read_unlock();
 }
 
 DEFINE_PER_CPU(struct pt_regs, __perf_regs[4]);
 
 int perf_swevent_get_recursion_context(void)
 {
         return get_recursion_context(current->perf_recursion);
 }
 EXPORT_SYMBOL_GPL(perf_swevent_get_recursion_context);
 
 void perf_swevent_put_recursion_context(int rctx)
 {
         put_recursion_context(current->perf_recursion, rctx);
 }
 
 void ___perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
 {
         struct perf_sample_data data;
 
         if (WARN_ON_ONCE(!regs))
                 return;
 
         perf_sample_data_init(&data, addr, 0);
         do_perf_sw_event(PERF_TYPE_SOFTWARE, event_id, nr, &data, regs);
 }
 
 void __perf_sw_event(u32 event_id, u64 nr, struct pt_regs *regs, u64 addr)
 {
         int rctx;
 
         preempt_disable_notrace();
         rctx = perf_swevent_get_recursion_context();
         if (unlikely(rctx < 0))
                 goto fail;
 
         ___perf_sw_event(event_id, nr, regs, addr);
 
         perf_swevent_put_recursion_context(rctx);
 fail:
         preempt_enable_notrace();
 }
 
 static void perf_swevent_read(struct perf_event *event)
 {
 }
 
 static int perf_swevent_add(struct perf_event *event, int flags)
 {
         struct swevent_htable *swhash = this_cpu_ptr(&swevent_htable);
         struct hw_perf_event *hwc = &event->hw;
         struct hlist_head *head;
 
         if (is_sampling_event(event)) {
                 hwc->last_period = hwc->sample_period;
                 perf_swevent_set_period(event);
         }
 
         hwc->state = !(flags & PERF_EF_START);
 
         head = find_swevent_head(swhash, event);
         if (WARN_ON_ONCE(!head))
                 return -EINVAL;
 
         hlist_add_head_rcu(&event->hlist_entry, head);
         perf_event_update_userpage(event);
 
         return 0;
 }
 
 static void perf_swevent_del(struct perf_event *event, int flags)
 {
         hlist_del_rcu(&event->hlist_entry);
 }
 
 static void perf_swevent_start(struct perf_event *event, int flags)
 {
         event->hw.state = 0;
 }
 
 static void perf_swevent_stop(struct perf_event *event, int flags)
 {
         event->hw.state = PERF_HES_STOPPED;
 }
 
 /* Deref the hlist from the update side */
 static inline struct swevent_hlist *
 swevent_hlist_deref(struct swevent_htable *swhash)
 {
         return rcu_dereference_protected(swhash->swevent_hlist,
                                          lockdep_is_held(&swhash->hlist_mutex));
 }
 
 static void swevent_hlist_release(struct swevent_htable *swhash)
 {
         struct swevent_hlist *hlist = swevent_hlist_deref(swhash);
 
         if (!hlist)
                 return;
 
         RCU_INIT_POINTER(swhash->swevent_hlist, NULL);
         kfree_rcu(hlist, rcu_head);
 }
 
 static void swevent_hlist_put_cpu(int cpu)
 {
         struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
 
         mutex_lock(&swhash->hlist_mutex);
 
         if (!--swhash->hlist_refcount)
                 swevent_hlist_release(swhash);
 
         mutex_unlock(&swhash->hlist_mutex);
 }
 
 static void swevent_hlist_put(void)
 {
         int cpu;
 
         for_each_possible_cpu(cpu)
                 swevent_hlist_put_cpu(cpu);
 }
 
 static int swevent_hlist_get_cpu(int cpu)
 {
         struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
         int err = 0;
 
         mutex_lock(&swhash->hlist_mutex);
         if (!swevent_hlist_deref(swhash) &&
             cpumask_test_cpu(cpu, perf_online_mask)) {
                 struct swevent_hlist *hlist;
 
                 hlist = kzalloc(sizeof(*hlist), GFP_KERNEL);
                 if (!hlist) {
                         err = -ENOMEM;
                         goto exit;
                 }
                 rcu_assign_pointer(swhash->swevent_hlist, hlist);
         }
         swhash->hlist_refcount++;
 exit:
         mutex_unlock(&swhash->hlist_mutex);
 
         return err;
 }
 
 static int swevent_hlist_get(void)
 {
         int err, cpu, failed_cpu;
 
         mutex_lock(&pmus_lock);
         for_each_possible_cpu(cpu) {
                 err = swevent_hlist_get_cpu(cpu);
                 if (err) {
                         failed_cpu = cpu;
                         goto fail;
                 }
         }
         mutex_unlock(&pmus_lock);
         return 0;
 fail:
         for_each_possible_cpu(cpu) {
                 if (cpu == failed_cpu)
                         break;
                 swevent_hlist_put_cpu(cpu);
         }
         mutex_unlock(&pmus_lock);
         return err;
 }
 
 struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
 
 static void sw_perf_event_destroy(struct perf_event *event)
 {
         u64 event_id = event->attr.config;
 
         WARN_ON(event->parent);
 
         static_key_slow_dec(&perf_swevent_enabled[event_id]);
         swevent_hlist_put();
 }
 
 static struct pmu perf_cpu_clock; /* fwd declaration */
 static struct pmu perf_task_clock;
 
 static int perf_swevent_init(struct perf_event *event)
 {
         u64 event_id = event->attr.config;
 
         if (event->attr.type != PERF_TYPE_SOFTWARE)
                 return -ENOENT;
 
         /*
          * no branch sampling for software events
          */
         if (has_branch_stack(event))
                 return -EOPNOTSUPP;
 
         switch (event_id) {
         case PERF_COUNT_SW_CPU_CLOCK:
                 event->attr.type = perf_cpu_clock.type;
                 return -ENOENT;
         case PERF_COUNT_SW_TASK_CLOCK:
                 event->attr.type = perf_task_clock.type;
                 return -ENOENT;
 
         default:
                 break;
         }
 
         if (event_id >= PERF_COUNT_SW_MAX)
                 return -ENOENT;
 
         if (!event->parent) {
                 int err;
 
                 err = swevent_hlist_get();
                 if (err)
                         return err;
 
                 static_key_slow_inc(&perf_swevent_enabled[event_id]);
                 event->destroy = sw_perf_event_destroy;
         }
 
         return 0;
 }
 
 static struct pmu perf_swevent = {
         .task_ctx_nr    = perf_sw_context,
 
         .capabilities   = PERF_PMU_CAP_NO_NMI,
 
         .event_init     = perf_swevent_init,
         .add            = perf_swevent_add,
         .del            = perf_swevent_del,
         .start          = perf_swevent_start,
         .stop           = perf_swevent_stop,
         .read           = perf_swevent_read,
 };
 
 #ifdef CONFIG_EVENT_TRACING
 
 static void tp_perf_event_destroy(struct perf_event *event)
 {
         perf_trace_destroy(event);
 }
 
 static int perf_tp_event_init(struct perf_event *event)
 {
         int err;
 
         if (event->attr.type != PERF_TYPE_TRACEPOINT)
                 return -ENOENT;
 
         /*
          * no branch sampling for tracepoint events
          */
         if (has_branch_stack(event))
                 return -EOPNOTSUPP;
 
         err = perf_trace_init(event);
         if (err)
                 return err;
 
         event->destroy = tp_perf_event_destroy;
 
         return 0;
 }
 
 static struct pmu perf_tracepoint = {
         .task_ctx_nr    = perf_sw_context,
 
         .event_init     = perf_tp_event_init,
         .add            = perf_trace_add,
         .del            = perf_trace_del,
         .start          = perf_swevent_start,
         .stop           = perf_swevent_stop,
         .read           = perf_swevent_read,
 };
 
 static int perf_tp_filter_match(struct perf_event *event,
                                 struct perf_sample_data *data)
 {
         void *record = data->raw->frag.data;
 
         /* only top level events have filters set */
         if (event->parent)
                 event = event->parent;
 
         if (likely(!event->filter) || filter_match_preds(event->filter, record))
                 return 1;
         return 0;
 }
 
 static int perf_tp_event_match(struct perf_event *event,
                                 struct perf_sample_data *data,
                                 struct pt_regs *regs)
 {
         if (event->hw.state & PERF_HES_STOPPED)
                 return 0;
         /*
          * If exclude_kernel, only trace user-space tracepoints (uprobes)
          */
         if (event->attr.exclude_kernel && !user_mode(regs))
                 return 0;
 
         if (!perf_tp_filter_match(event, data))
                 return 0;
 
         return 1;
 }
 
 void perf_trace_run_bpf_submit(void *raw_data, int size, int rctx,
                                struct trace_event_call *call, u64 count,
                                struct pt_regs *regs, struct hlist_head *head,
                                struct task_struct *task)
 {
         if (bpf_prog_array_valid(call)) {
                 *(struct pt_regs **)raw_data = regs;
                 if (!trace_call_bpf(call, raw_data) || hlist_empty(head)) {
                         perf_swevent_put_recursion_context(rctx);
                         return;
                 }
         }
         perf_tp_event(call->event.type, count, raw_data, size, regs, head,
                       rctx, task);
 }
 EXPORT_SYMBOL_GPL(perf_trace_run_bpf_submit);
 
 static void __perf_tp_event_target_task(u64 count, void *record,
                                         struct pt_regs *regs,
                                         struct perf_sample_data *data,
                                         struct perf_event *event)
 {
         struct trace_entry *entry = record;
 
         if (event->attr.config != entry->type)
                 return;
         /* Cannot deliver synchronous signal to other task. */
         if (event->attr.sigtrap)
                 return;
         if (perf_tp_event_match(event, data, regs))
                 perf_swevent_event(event, count, data, regs);
 }
 
 static void perf_tp_event_target_task(u64 count, void *record,
                                       struct pt_regs *regs,
                                       struct perf_sample_data *data,
                                       struct perf_event_context *ctx)
 {
         unsigned int cpu = smp_processor_id();
         struct pmu *pmu = &perf_tracepoint;
         struct perf_event *event, *sibling;
 
         perf_event_groups_for_cpu_pmu(event, &ctx->pinned_groups, cpu, pmu) {
                 __perf_tp_event_target_task(count, record, regs, data, event);
                 for_each_sibling_event(sibling, event)
                         __perf_tp_event_target_task(count, record, regs, data, sibling);
         }
 
         perf_event_groups_for_cpu_pmu(event, &ctx->flexible_groups, cpu, pmu) {
                 __perf_tp_event_target_task(count, record, regs, data, event);
                 for_each_sibling_event(sibling, event)
                         __perf_tp_event_target_task(count, record, regs, data, sibling);
         }
 }
 
 void perf_tp_event(u16 event_type, u64 count, void *record, int entry_size,
                    struct pt_regs *regs, struct hlist_head *head, int rctx,
                    struct task_struct *task)
 {
         struct perf_sample_data data;
         struct perf_event *event;
 
         struct perf_raw_record raw = {
                 .frag = {
                         .size = entry_size,
                         .data = record,
                 },
         };
 
         perf_sample_data_init(&data, 0, 0);
         perf_sample_save_raw_data(&data, &raw);
 
         perf_trace_buf_update(record, event_type);
 
         hlist_for_each_entry_rcu(event, head, hlist_entry) {
                 if (perf_tp_event_match(event, &data, regs)) {
                         perf_swevent_event(event, count, &data, regs);
 
                         /*
                          * Here use the same on-stack perf_sample_data,
                          * some members in data are event-specific and
                          * need to be re-computed for different sweveents.
                          * Re-initialize data->sample_flags safely to avoid
                          * the problem that next event skips preparing data
                          * because data->sample_flags is set.
                          */
                         perf_sample_data_init(&data, 0, 0);
                         perf_sample_save_raw_data(&data, &raw);
                 }
         }
 
         /*
          * If we got specified a target task, also iterate its context and
          * deliver this event there too.
          */
         if (task && task != current) {
                 struct perf_event_context *ctx;
 
                 rcu_read_lock();
                 ctx = rcu_dereference(task->perf_event_ctxp);
                 if (!ctx)
                         goto unlock;
 
                 raw_spin_lock(&ctx->lock);
                 perf_tp_event_target_task(count, record, regs, &data, ctx);
                 raw_spin_unlock(&ctx->lock);
 unlock:
                 rcu_read_unlock();
         }
 
         perf_swevent_put_recursion_context(rctx);
 }
 EXPORT_SYMBOL_GPL(perf_tp_event);
 
 #if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
 /*
  * Flags in config, used by dynamic PMU kprobe and uprobe
  * The flags should match following PMU_FORMAT_ATTR().
  *
  * PERF_PROBE_CONFIG_IS_RETPROBE if set, create kretprobe/uretprobe
  *                               if not set, create kprobe/uprobe
  *
  * The following values specify a reference counter (or semaphore in the
  * terminology of tools like dtrace, systemtap, etc.) Userspace Statically
  * Defined Tracepoints (USDT). Currently, we use 40 bit for the offset.
  *
  * PERF_UPROBE_REF_CTR_OFFSET_BITS      # of bits in config as th offset
  * PERF_UPROBE_REF_CTR_OFFSET_SHIFT     # of bits to shift left
  */
 enum perf_probe_config {
         PERF_PROBE_CONFIG_IS_RETPROBE = 1U << 0,  /* [k,u]retprobe */
         PERF_UPROBE_REF_CTR_OFFSET_BITS = 32,
         PERF_UPROBE_REF_CTR_OFFSET_SHIFT = 64 - PERF_UPROBE_REF_CTR_OFFSET_BITS,
 };
 
 PMU_FORMAT_ATTR(retprobe, "config:0");
 #endif
 
 #ifdef CONFIG_KPROBE_EVENTS
 static struct attribute *kprobe_attrs[] = {
         &format_attr_retprobe.attr,
         NULL,
 };
 
 static struct attribute_group kprobe_format_group = {
         .name = "format",
         .attrs = kprobe_attrs,
 };
 
 static const struct attribute_group *kprobe_attr_groups[] = {
         &kprobe_format_group,
         NULL,
 };
 
 static int perf_kprobe_event_init(struct perf_event *event);
 static struct pmu perf_kprobe = {
         .task_ctx_nr    = perf_sw_context,
         .event_init     = perf_kprobe_event_init,
         .add            = perf_trace_add,
         .del            = perf_trace_del,
         .start          = perf_swevent_start,
         .stop           = perf_swevent_stop,
         .read           = perf_swevent_read,
         .attr_groups    = kprobe_attr_groups,
 };
 
 static int perf_kprobe_event_init(struct perf_event *event)
 {
         int err;
         bool is_retprobe;
 
         if (event->attr.type != perf_kprobe.type)
                 return -ENOENT;
 
         if (!perfmon_capable())
                 return -EACCES;
 
         /*
          * no branch sampling for probe events
          */
         if (has_branch_stack(event))
                 return -EOPNOTSUPP;
 
         is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
         err = perf_kprobe_init(event, is_retprobe);
         if (err)
                 return err;
 
         event->destroy = perf_kprobe_destroy;
 
         return 0;
 }
 #endif /* CONFIG_KPROBE_EVENTS */
 
 #ifdef CONFIG_UPROBE_EVENTS
 PMU_FORMAT_ATTR(ref_ctr_offset, "config:32-63");
 
 static struct attribute *uprobe_attrs[] = {
         &format_attr_retprobe.attr,
         &format_attr_ref_ctr_offset.attr,
         NULL,
 };
 
 static struct attribute_group uprobe_format_group = {
         .name = "format",
         .attrs = uprobe_attrs,
 };
 
 static const struct attribute_group *uprobe_attr_groups[] = {
         &uprobe_format_group,
         NULL,
 };
 
 static int perf_uprobe_event_init(struct perf_event *event);
 static struct pmu perf_uprobe = {
         .task_ctx_nr    = perf_sw_context,
         .event_init     = perf_uprobe_event_init,
         .add            = perf_trace_add,
         .del            = perf_trace_del,
         .start          = perf_swevent_start,
         .stop           = perf_swevent_stop,
         .read           = perf_swevent_read,
         .attr_groups    = uprobe_attr_groups,
 };
 
 static int perf_uprobe_event_init(struct perf_event *event)
 {
         int err;
         unsigned long ref_ctr_offset;
         bool is_retprobe;
 
         if (event->attr.type != perf_uprobe.type)
                 return -ENOENT;
 
         if (!perfmon_capable())
                 return -EACCES;
 
         /*
          * no branch sampling for probe events
          */
         if (has_branch_stack(event))
                 return -EOPNOTSUPP;
 
         is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
         ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
         err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe);
         if (err)
                 return err;
 
         event->destroy = perf_uprobe_destroy;
 
         return 0;
 }
 #endif /* CONFIG_UPROBE_EVENTS */
 
 static inline void perf_tp_register(void)
 {
         perf_pmu_register(&perf_tracepoint, "tracepoint", PERF_TYPE_TRACEPOINT);
 #ifdef CONFIG_KPROBE_EVENTS
         perf_pmu_register(&perf_kprobe, "kprobe", -1);
 #endif
 #ifdef CONFIG_UPROBE_EVENTS
         perf_pmu_register(&perf_uprobe, "uprobe", -1);
 #endif
 }
 
 static void perf_event_free_filter(struct perf_event *event)
 {
         ftrace_profile_free_filter(event);
 }
 
 /*
  * returns true if the event is a tracepoint, or a kprobe/upprobe created
  * with perf_event_open()
  */
 static inline bool perf_event_is_tracing(struct perf_event *event)
 {
         if (event->pmu == &perf_tracepoint)
                 return true;
 #ifdef CONFIG_KPROBE_EVENTS
         if (event->pmu == &perf_kprobe)
                 return true;
 #endif
 #ifdef CONFIG_UPROBE_EVENTS
         if (event->pmu == &perf_uprobe)
                 return true;
 #endif
         return false;
 }
 
 int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,
                             u64 bpf_cookie)
 {
         bool is_kprobe, is_uprobe, is_tracepoint, is_syscall_tp;
 
         if (!perf_event_is_tracing(event))
                 return perf_event_set_bpf_handler(event, prog, bpf_cookie);
 
         is_kprobe = event->tp_event->flags & TRACE_EVENT_FL_KPROBE;
         is_uprobe = event->tp_event->flags & TRACE_EVENT_FL_UPROBE;
         is_tracepoint = event->tp_event->flags & TRACE_EVENT_FL_TRACEPOINT;
         is_syscall_tp = is_syscall_trace_event(event->tp_event);
         if (!is_kprobe && !is_uprobe && !is_tracepoint && !is_syscall_tp)
                 /* bpf programs can only be attached to u/kprobe or tracepoint */
                 return -EINVAL;
 
         if (((is_kprobe || is_uprobe) && prog->type != BPF_PROG_TYPE_KPROBE) ||
             (is_tracepoint && prog->type != BPF_PROG_TYPE_TRACEPOINT) ||
             (is_syscall_tp && prog->type != BPF_PROG_TYPE_TRACEPOINT))
                 return -EINVAL;
 
         if (prog->type == BPF_PROG_TYPE_KPROBE && prog->sleepable && !is_uprobe)
                 /* only uprobe programs are allowed to be sleepable */
                 return -EINVAL;
 
         /* Kprobe override only works for kprobes, not uprobes. */
         if (prog->kprobe_override && !is_kprobe)
                 return -EINVAL;
 
         if (is_tracepoint || is_syscall_tp) {
                 int off = trace_event_get_offsets(event->tp_event);
 
                 if (prog->aux->max_ctx_offset > off)
                         return -EACCES;
         }
 
         return perf_event_attach_bpf_prog(event, prog, bpf_cookie);
 }
 
 void perf_event_free_bpf_prog(struct perf_event *event)
 {
         if (!perf_event_is_tracing(event)) {
                 perf_event_free_bpf_handler(event);
                 return;
         }
         perf_event_detach_bpf_prog(event);
 }
 
 #else
 
 static inline void perf_tp_register(void)
 {
 }
 
 static void perf_event_free_filter(struct perf_event *event)
 {
 }
 
 int perf_event_set_bpf_prog(struct perf_event *event, struct bpf_prog *prog,
                             u64 bpf_cookie)
 {
         return -ENOENT;
 }
 
 void perf_event_free_bpf_prog(struct perf_event *event)
 {
 }
 #endif /* CONFIG_EVENT_TRACING */
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 void perf_bp_event(struct perf_event *bp, void *data)
 {
         struct perf_sample_data sample;
         struct pt_regs *regs = data;
 
         perf_sample_data_init(&sample, bp->attr.bp_addr, 0);
 
         if (!bp->hw.state && !perf_exclude_event(bp, regs))
                 perf_swevent_event(bp, 1, &sample, regs);
 }
 #endif
 
 /*
  * Allocate a new address filter
  */
 static struct perf_addr_filter *
 perf_addr_filter_new(struct perf_event *event, struct list_head *filters)
 {
         int node = cpu_to_node(event->cpu == -1 ? 0 : event->cpu);
         struct perf_addr_filter *filter;
 
         filter = kzalloc_node(sizeof(*filter), GFP_KERNEL, node);
         if (!filter)
                 return NULL;
 
         INIT_LIST_HEAD(&filter->entry);
         list_add_tail(&filter->entry, filters);
 
         return filter;
 }
 
 static void free_filters_list(struct list_head *filters)
 {
         struct perf_addr_filter *filter, *iter;
 
         list_for_each_entry_safe(filter, iter, filters, entry) {
                 path_put(&filter->path);
                 list_del(&filter->entry);
                 kfree(filter);
         }
 }
 
 /*
  * Free existing address filters and optionally install new ones
  */
 static void perf_addr_filters_splice(struct perf_event *event,
                                      struct list_head *head)
 {
         unsigned long flags;
         LIST_HEAD(list);
 
         if (!has_addr_filter(event))
                 return;
 
         /* don't bother with children, they don't have their own filters */
         if (event->parent)
                 return;
 
         raw_spin_lock_irqsave(&event->addr_filters.lock, flags);
 
         list_splice_init(&event->addr_filters.list, &list);
         if (head)
                 list_splice(head, &event->addr_filters.list);
 
         raw_spin_unlock_irqrestore(&event->addr_filters.lock, flags);
 
         free_filters_list(&list);
 }
 
 /*
  * Scan through mm's vmas and see if one of them matches the
  * @filter; if so, adjust filter's address range.
  * Called with mm::mmap_lock down for reading.
  */
 static void perf_addr_filter_apply(struct perf_addr_filter *filter,
                                    struct mm_struct *mm,
                                    struct perf_addr_filter_range *fr)
 {
         struct vm_area_struct *vma;
         VMA_ITERATOR(vmi, mm, 0);
 
         for_each_vma(vmi, vma) {
                 if (!vma->vm_file)
                         continue;
 
                 if (perf_addr_filter_vma_adjust(filter, vma, fr))
                         return;
         }
 }
 
 /*
  * Update event's address range filters based on the
  * task's existing mappings, if any.
  */
 static void perf_event_addr_filters_apply(struct perf_event *event)
 {
         struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
         struct task_struct *task = READ_ONCE(event->ctx->task);
         struct perf_addr_filter *filter;
         struct mm_struct *mm = NULL;
         unsigned int count = 0;
         unsigned long flags;
 
         /*
          * We may observe TASK_TOMBSTONE, which means that the event tear-down
          * will stop on the parent's child_mutex that our caller is also holding
          */
         if (task == TASK_TOMBSTONE)
                 return;
 
         if (ifh->nr_file_filters) {
                 mm = get_task_mm(task);
                 if (!mm)
                         goto restart;
 
                 mmap_read_lock(mm);
         }
 
         raw_spin_lock_irqsave(&ifh->lock, flags);
         list_for_each_entry(filter, &ifh->list, entry) {
                 if (filter->path.dentry) {
                         /*
                          * Adjust base offset if the filter is associated to a
                          * binary that needs to be mapped:
                          */
                         event->addr_filter_ranges[count].start = 0;
                         event->addr_filter_ranges[count].size = 0;
 
                         perf_addr_filter_apply(filter, mm, &event->addr_filter_ranges[count]);
                 } else {
                         event->addr_filter_ranges[count].start = filter->offset;
                         event->addr_filter_ranges[count].size  = filter->size;
                 }
 
                 count++;
         }
 
         event->addr_filters_gen++;
         raw_spin_unlock_irqrestore(&ifh->lock, flags);
 
         if (ifh->nr_file_filters) {
                 mmap_read_unlock(mm);
 
                 mmput(mm);
         }
 
 restart:
         perf_event_stop(event, 1);
 }
 
 /*
  * Address range filtering: limiting the data to certain
  * instruction address ranges. Filters are ioctl()ed to us from
  * userspace as ascii strings.
  *
  * Filter string format:
  *
  * ACTION RANGE_SPEC
  * where ACTION is one of the
  *  * "filter": limit the trace to this region
  *  * "start": start tracing from this address
  *  * "stop": stop tracing at this address/region;
  * RANGE_SPEC is
  *  * for kernel addresses: <start address>[/<size>]
  *  * for object files:     <start address>[/<size>]@</path/to/object/file>
  *
  * if <size> is not specified or is zero, the range is treated as a single
  * address; not valid for ACTION=="filter".
  */
 enum {
         IF_ACT_NONE = -1,
         IF_ACT_FILTER,
         IF_ACT_START,
         IF_ACT_STOP,
         IF_SRC_FILE,
         IF_SRC_KERNEL,
         IF_SRC_FILEADDR,
         IF_SRC_KERNELADDR,
 };
 
 enum {
         IF_STATE_ACTION = 0,
         IF_STATE_SOURCE,
         IF_STATE_END,
 };
 
 static const match_table_t if_tokens = {
         { IF_ACT_FILTER,        "filter" },
         { IF_ACT_START,         "start" },
         { IF_ACT_STOP,          "stop" },
         { IF_SRC_FILE,          "%u/%u@%s" },
         { IF_SRC_KERNEL,        "%u/%u" },
         { IF_SRC_FILEADDR,      "%u@%s" },
         { IF_SRC_KERNELADDR,    "%u" },
         { IF_ACT_NONE,          NULL },
 };
 
 /*
  * Address filter string parser
  */
 static int
 perf_event_parse_addr_filter(struct perf_event *event, char *fstr,
                              struct list_head *filters)
 {
         struct perf_addr_filter *filter = NULL;
         char *start, *orig, *filename = NULL;
         substring_t args[MAX_OPT_ARGS];
         int state = IF_STATE_ACTION, token;
         unsigned int kernel = 0;
         int ret = -EINVAL;
 
         orig = fstr = kstrdup(fstr, GFP_KERNEL);
         if (!fstr)
                 return -ENOMEM;
 
         while ((start = strsep(&fstr, " ,\n")) != NULL) {
                 static const enum perf_addr_filter_action_t actions[] = {
                         [IF_ACT_FILTER] = PERF_ADDR_FILTER_ACTION_FILTER,
                         [IF_ACT_START]  = PERF_ADDR_FILTER_ACTION_START,
                         [IF_ACT_STOP]   = PERF_ADDR_FILTER_ACTION_STOP,
                 };
                 ret = -EINVAL;
 
                 if (!*start)
                         continue;
 
                 /* filter definition begins */
                 if (state == IF_STATE_ACTION) {
                         filter = perf_addr_filter_new(event, filters);
                         if (!filter)
                                 goto fail;
                 }
 
                 token = match_token(start, if_tokens, args);
                 switch (token) {
                 case IF_ACT_FILTER:
                 case IF_ACT_START:
                 case IF_ACT_STOP:
                         if (state != IF_STATE_ACTION)
                                 goto fail;
 
                         filter->action = actions[token];
                         state = IF_STATE_SOURCE;
                         break;
 
                 case IF_SRC_KERNELADDR:
                 case IF_SRC_KERNEL:
                         kernel = 1;
                         fallthrough;
 
                 case IF_SRC_FILEADDR:
                 case IF_SRC_FILE:
                         if (state != IF_STATE_SOURCE)
                                 goto fail;
 
                         *args[0].to = 0;
                         ret = kstrtoul(args[0].from, 0, &filter->offset);
                         if (ret)
                                 goto fail;
 
                         if (token == IF_SRC_KERNEL || token == IF_SRC_FILE) {
                                 *args[1].to = 0;
                                 ret = kstrtoul(args[1].from, 0, &filter->size);
                                 if (ret)
                                         goto fail;
                         }
 
                         if (token == IF_SRC_FILE || token == IF_SRC_FILEADDR) {
                                 int fpos = token == IF_SRC_FILE ? 2 : 1;
 
                                 kfree(filename);
                                 filename = match_strdup(&args[fpos]);
                                 if (!filename) {
                                         ret = -ENOMEM;
                                         goto fail;
                                 }
                         }
 
                         state = IF_STATE_END;
                         break;
 
                 default:
                         goto fail;
                 }
 
                 /*
                  * Filter definition is fully parsed, validate and install it.
                  * Make sure that it doesn't contradict itself or the event's
                  * attribute.
                  */
                 if (state == IF_STATE_END) {
                         ret = -EINVAL;
 
                         /*
                          * ACTION "filter" must have a non-zero length region
                          * specified.
                          */
                         if (filter->action == PERF_ADDR_FILTER_ACTION_FILTER &&
                             !filter->size)
                                 goto fail;
 
                         if (!kernel) {
                                 if (!filename)
                                         goto fail;
 
                                 /*
                                  * For now, we only support file-based filters
                                  * in per-task events; doing so for CPU-wide
                                  * events requires additional context switching
                                  * trickery, since same object code will be
                                  * mapped at different virtual addresses in
                                  * different processes.
                                  */
                                 ret = -EOPNOTSUPP;
                                 if (!event->ctx->task)
                                         goto fail;
 
                                 /* look up the path and grab its inode */
                                 ret = kern_path(filename, LOOKUP_FOLLOW,
                                                 &filter->path);
                                 if (ret)
                                         goto fail;
 
                                 ret = -EINVAL;
                                 if (!filter->path.dentry ||
                                     !S_ISREG(d_inode(filter->path.dentry)
                                              ->i_mode))
                                         goto fail;
 
                                 event->addr_filters.nr_file_filters++;
                         }
 
                         /* ready to consume more filters */
                         kfree(filename);
                         filename = NULL;
                         state = IF_STATE_ACTION;
                         filter = NULL;
                         kernel = 0;
                 }
         }
 
         if (state != IF_STATE_ACTION)
                 goto fail;
 
         kfree(filename);
         kfree(orig);
 
         return 0;
 
 fail:
         kfree(filename);
         free_filters_list(filters);
         kfree(orig);
 
         return ret;
 }
 
 static int
 perf_event_set_addr_filter(struct perf_event *event, char *filter_str)
 {
         LIST_HEAD(filters);
         int ret;
 
         /*
          * Since this is called in perf_ioctl() path, we're already holding
          * ctx::mutex.
          */
         lockdep_assert_held(&event->ctx->mutex);
 
         if (WARN_ON_ONCE(event->parent))
                 return -EINVAL;
 
         ret = perf_event_parse_addr_filter(event, filter_str, &filters);
         if (ret)
                 goto fail_clear_files;
 
         ret = event->pmu->addr_filters_validate(&filters);
         if (ret)
                 goto fail_free_filters;
 
         /* remove existing filters, if any */
         perf_addr_filters_splice(event, &filters);
 
         /* install new filters */
         perf_event_for_each_child(event, perf_event_addr_filters_apply);
 
         return ret;
 
 fail_free_filters:
         free_filters_list(&filters);
 
 fail_clear_files:
         event->addr_filters.nr_file_filters = 0;
 
         return ret;
 }
 
 static int perf_event_set_filter(struct perf_event *event, void __user *arg)
 {
         int ret = -EINVAL;
         char *filter_str;
 
         filter_str = strndup_user(arg, PAGE_SIZE);
         if (IS_ERR(filter_str))
                 return PTR_ERR(filter_str);
 
 #ifdef CONFIG_EVENT_TRACING
         if (perf_event_is_tracing(event)) {
                 struct perf_event_context *ctx = event->ctx;
 
                 /*
                  * Beware, here be dragons!!
                  *
                  * the tracepoint muck will deadlock against ctx->mutex, but
                  * the tracepoint stuff does not actually need it. So
                  * temporarily drop ctx->mutex. As per perf_event_ctx_lock() we
                  * already have a reference on ctx.
                  *
                  * This can result in event getting moved to a different ctx,
                  * but that does not affect the tracepoint state.
                  */
                 mutex_unlock(&ctx->mutex);
                 ret = ftrace_profile_set_filter(event, event->attr.config, filter_str);
                 mutex_lock(&ctx->mutex);
         } else
 #endif
         if (has_addr_filter(event))
                 ret = perf_event_set_addr_filter(event, filter_str);
 
         kfree(filter_str);
         return ret;
 }
 
 /*
  * hrtimer based swevent callback
  */
 
 static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer)
 {
         enum hrtimer_restart ret = HRTIMER_RESTART;
         struct perf_sample_data data;
         struct pt_regs *regs;
         struct perf_event *event;
         u64 period;
 
         event = container_of(hrtimer, struct perf_event, hw.hrtimer);
 
         if (event->state != PERF_EVENT_STATE_ACTIVE)
                 return HRTIMER_NORESTART;
 
         event->pmu->read(event);
 
         perf_sample_data_init(&data, 0, event->hw.last_period);
         regs = get_irq_regs();
 
         if (regs && !perf_exclude_event(event, regs)) {
                 if (!(event->attr.exclude_idle && is_idle_task(current)))
                         if (__perf_event_overflow(event, 1, &data, regs))
                                 ret = HRTIMER_NORESTART;
         }
 
         period = max_t(u64, 10000, event->hw.sample_period);
         hrtimer_forward_now(hrtimer, ns_to_ktime(period));
 
         return ret;
 }
 
 static void perf_swevent_start_hrtimer(struct perf_event *event)
 {
         struct hw_perf_event *hwc = &event->hw;
         s64 period;
 
         if (!is_sampling_event(event))
                 return;
 
         period = local64_read(&hwc->period_left);
         if (period) {
                 if (period < 0)
                         period = 10000;
 
                 local64_set(&hwc->period_left, 0);
         } else {
                 period = max_t(u64, 10000, hwc->sample_period);
         }
         hrtimer_start(&hwc->hrtimer, ns_to_ktime(period),
                       HRTIMER_MODE_REL_PINNED_HARD);
 }
 
 static void perf_swevent_cancel_hrtimer(struct perf_event *event)
 {
         struct hw_perf_event *hwc = &event->hw;
 
         if (is_sampling_event(event)) {
                 ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
                 local64_set(&hwc->period_left, ktime_to_ns(remaining));
 
                 hrtimer_cancel(&hwc->hrtimer);
         }
 }
 
 static void perf_swevent_init_hrtimer(struct perf_event *event)
 {
         struct hw_perf_event *hwc = &event->hw;
 
         if (!is_sampling_event(event))
                 return;
 
         hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
         hwc->hrtimer.function = perf_swevent_hrtimer;
 
         /*
          * Since hrtimers have a fixed rate, we can do a static freq->period
          * mapping and avoid the whole period adjust feedback stuff.
          */
         if (event->attr.freq) {
                 long freq = event->attr.sample_freq;
 
                 event->attr.sample_period = NSEC_PER_SEC / freq;
                 hwc->sample_period = event->attr.sample_period;
                 local64_set(&hwc->period_left, hwc->sample_period);
                 hwc->last_period = hwc->sample_period;
                 event->attr.freq = 0;
         }
 }
 
 /*
  * Software event: cpu wall time clock
  */
 
 static void cpu_clock_event_update(struct perf_event *event)
 {
         s64 prev;
         u64 now;
 
         now = local_clock();
         prev = local64_xchg(&event->hw.prev_count, now);
         local64_add(now - prev, &event->count);
 }
 
 static void cpu_clock_event_start(struct perf_event *event, int flags)
 {
         local64_set(&event->hw.prev_count, local_clock());
         perf_swevent_start_hrtimer(event);
 }
 
 static void cpu_clock_event_stop(struct perf_event *event, int flags)
 {
         perf_swevent_cancel_hrtimer(event);
         cpu_clock_event_update(event);
 }
 
 static int cpu_clock_event_add(struct perf_event *event, int flags)
 {
         if (flags & PERF_EF_START)
                 cpu_clock_event_start(event, flags);
         perf_event_update_userpage(event);
 
         return 0;
 }
 
 static void cpu_clock_event_del(struct perf_event *event, int flags)
 {
         cpu_clock_event_stop(event, flags);
 }
 
 static void cpu_clock_event_read(struct perf_event *event)
 {
         cpu_clock_event_update(event);
 }
 
 static int cpu_clock_event_init(struct perf_event *event)
 {
         if (event->attr.type != perf_cpu_clock.type)
                 return -ENOENT;
 
         if (event->attr.config != PERF_COUNT_SW_CPU_CLOCK)
                 return -ENOENT;
 
         /*
          * no branch sampling for software events
          */
         if (has_branch_stack(event))
                 return -EOPNOTSUPP;
 
         perf_swevent_init_hrtimer(event);
 
         return 0;
 }
 
 static struct pmu perf_cpu_clock = {
         .task_ctx_nr    = perf_sw_context,
 
         .capabilities   = PERF_PMU_CAP_NO_NMI,
         .dev            = PMU_NULL_DEV,
 
         .event_init     = cpu_clock_event_init,
         .add            = cpu_clock_event_add,
         .del            = cpu_clock_event_del,
         .start          = cpu_clock_event_start,
         .stop           = cpu_clock_event_stop,
         .read           = cpu_clock_event_read,
 };
 
 /*
  * Software event: task time clock
  */
 
 static void task_clock_event_update(struct perf_event *event, u64 now)
 {
         u64 prev;
         s64 delta;
 
         prev = local64_xchg(&event->hw.prev_count, now);
         delta = now - prev;
         local64_add(delta, &event->count);
 }
 
 static void task_clock_event_start(struct perf_event *event, int flags)
 {
         local64_set(&event->hw.prev_count, event->ctx->time);
         perf_swevent_start_hrtimer(event);
 }
 
 static void task_clock_event_stop(struct perf_event *event, int flags)
 {
         perf_swevent_cancel_hrtimer(event);
         task_clock_event_update(event, event->ctx->time);
 }
 
 static int task_clock_event_add(struct perf_event *event, int flags)
 {
         if (flags & PERF_EF_START)
                 task_clock_event_start(event, flags);
         perf_event_update_userpage(event);
 
         return 0;
 }
 
 static void task_clock_event_del(struct perf_event *event, int flags)
 {
         task_clock_event_stop(event, PERF_EF_UPDATE);
 }
 
 static void task_clock_event_read(struct perf_event *event)
 {
         u64 now = perf_clock();
         u64 delta = now - event->ctx->timestamp;
         u64 time = event->ctx->time + delta;
 
         task_clock_event_update(event, time);
 }
 
 static int task_clock_event_init(struct perf_event *event)
 {
         if (event->attr.type != perf_task_clock.type)
                 return -ENOENT;
 
         if (event->attr.config != PERF_COUNT_SW_TASK_CLOCK)
                 return -ENOENT;
 
         /*
          * no branch sampling for software events
          */
         if (has_branch_stack(event))
                 return -EOPNOTSUPP;
 
         perf_swevent_init_hrtimer(event);
 
         return 0;
 }
 
 static struct pmu perf_task_clock = {
         .task_ctx_nr    = perf_sw_context,
 
         .capabilities   = PERF_PMU_CAP_NO_NMI,
         .dev            = PMU_NULL_DEV,
 
         .event_init     = task_clock_event_init,
         .add            = task_clock_event_add,
         .del            = task_clock_event_del,
         .start          = task_clock_event_start,
         .stop           = task_clock_event_stop,
         .read           = task_clock_event_read,
 };
 
 static void perf_pmu_nop_void(struct pmu *pmu)
 {
 }
 
 static void perf_pmu_nop_txn(struct pmu *pmu, unsigned int flags)
 {
 }
 
 static int perf_pmu_nop_int(struct pmu *pmu)
 {
         return 0;
 }
 
 static int perf_event_nop_int(struct perf_event *event, u64 value)
 {
         return 0;
 }
 
 static DEFINE_PER_CPU(unsigned int, nop_txn_flags);
 
 static void perf_pmu_start_txn(struct pmu *pmu, unsigned int flags)
 {
         __this_cpu_write(nop_txn_flags, flags);
 
         if (flags & ~PERF_PMU_TXN_ADD)
                 return;
 
         perf_pmu_disable(pmu);
 }
 
 static int perf_pmu_commit_txn(struct pmu *pmu)
 {
         unsigned int flags = __this_cpu_read(nop_txn_flags);
 
         __this_cpu_write(nop_txn_flags, 0);
 
         if (flags & ~PERF_PMU_TXN_ADD)
                 return 0;
 
         perf_pmu_enable(pmu);
         return 0;
 }
 
 static void perf_pmu_cancel_txn(struct pmu *pmu)
 {
         unsigned int flags =  __this_cpu_read(nop_txn_flags);
 
         __this_cpu_write(nop_txn_flags, 0);
 
         if (flags & ~PERF_PMU_TXN_ADD)
                 return;
 
         perf_pmu_enable(pmu);
 }
 
 static int perf_event_idx_default(struct perf_event *event)
 {
         return 0;
 }
 
 static void free_pmu_context(struct pmu *pmu)
 {
         free_percpu(pmu->cpu_pmu_context);
 }
 
 /*
  * Let userspace know that this PMU supports address range filtering:
  */
 static ssize_t nr_addr_filters_show(struct device *dev,
                                     struct device_attribute *attr,
                                     char *page)
 {
         struct pmu *pmu = dev_get_drvdata(dev);
 
         return scnprintf(page, PAGE_SIZE - 1, "%d\n", pmu->nr_addr_filters);
 }
 DEVICE_ATTR_RO(nr_addr_filters);
 
 static struct idr pmu_idr;
 
 static ssize_t
 type_show(struct device *dev, struct device_attribute *attr, char *page)
 {
         struct pmu *pmu = dev_get_drvdata(dev);
 
         return scnprintf(page, PAGE_SIZE - 1, "%d\n", pmu->type);
 }
 static DEVICE_ATTR_RO(type);
 
 static ssize_t
 perf_event_mux_interval_ms_show(struct device *dev,
                                 struct device_attribute *attr,
                                 char *page)
 {
         struct pmu *pmu = dev_get_drvdata(dev);
 
         return scnprintf(page, PAGE_SIZE - 1, "%d\n", pmu->hrtimer_interval_ms);
 }
 
 static DEFINE_MUTEX(mux_interval_mutex);
 
 static ssize_t
 perf_event_mux_interval_ms_store(struct device *dev,
                                  struct device_attribute *attr,
                                  const char *buf, size_t count)
 {
         struct pmu *pmu = dev_get_drvdata(dev);
         int timer, cpu, ret;
 
         ret = kstrtoint(buf, 0, &timer);
         if (ret)
                 return ret;
 
         if (timer < 1)
                 return -EINVAL;
 
         /* same value, noting to do */
         if (timer == pmu->hrtimer_interval_ms)
                 return count;
 
         mutex_lock(&mux_interval_mutex);
         pmu->hrtimer_interval_ms = timer;
 
         /* update all cpuctx for this PMU */
         cpus_read_lock();
         for_each_online_cpu(cpu) {
                 struct perf_cpu_pmu_context *cpc;
                 cpc = per_cpu_ptr(pmu->cpu_pmu_context, cpu);
                 cpc->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer);
 
                 cpu_function_call(cpu, perf_mux_hrtimer_restart_ipi, cpc);
         }
         cpus_read_unlock();
         mutex_unlock(&mux_interval_mutex);
 
         return count;
 }
 static DEVICE_ATTR_RW(perf_event_mux_interval_ms);
 
 static struct attribute *pmu_dev_attrs[] = {
         &dev_attr_type.attr,
         &dev_attr_perf_event_mux_interval_ms.attr,
         &dev_attr_nr_addr_filters.attr,
         NULL,
 };
 
 static umode_t pmu_dev_is_visible(struct kobject *kobj, struct attribute *a, int n)
 {
         struct device *dev = kobj_to_dev(kobj);
         struct pmu *pmu = dev_get_drvdata(dev);
 
         if (n == 2 && !pmu->nr_addr_filters)
                 return 0;
 
         return a->mode;
 }
 
 static struct attribute_group pmu_dev_attr_group = {
         .is_visible = pmu_dev_is_visible,
         .attrs = pmu_dev_attrs,
 };
 
 static const struct attribute_group *pmu_dev_groups[] = {
         &pmu_dev_attr_group,
         NULL,
 };
 
 static int pmu_bus_running;
 static struct bus_type pmu_bus = {
         .name           = "event_source",
         .dev_groups     = pmu_dev_groups,
 };
 
 static void pmu_dev_release(struct device *dev)
 {
         kfree(dev);
 }
 
 static int pmu_dev_alloc(struct pmu *pmu)
 {
         int ret = -ENOMEM;
 
         pmu->dev = kzalloc(sizeof(struct device), GFP_KERNEL);
         if (!pmu->dev)
                 goto out;
 
         pmu->dev->groups = pmu->attr_groups;
         device_initialize(pmu->dev);
 
         dev_set_drvdata(pmu->dev, pmu);
         pmu->dev->bus = &pmu_bus;
         pmu->dev->parent = pmu->parent;
         pmu->dev->release = pmu_dev_release;
 
         ret = dev_set_name(pmu->dev, "%s", pmu->name);
         if (ret)
                 goto free_dev;
 
         ret = device_add(pmu->dev);
         if (ret)
                 goto free_dev;
 
         if (pmu->attr_update) {
                 ret = sysfs_update_groups(&pmu->dev->kobj, pmu->attr_update);
                 if (ret)
                         goto del_dev;
         }
 
 out:
         return ret;
 
 del_dev:
         device_del(pmu->dev);
 
 free_dev:
         put_device(pmu->dev);
         goto out;
 }
 
 static struct lock_class_key cpuctx_mutex;
 static struct lock_class_key cpuctx_lock;
 
 int perf_pmu_register(struct pmu *pmu, const char *name, int type)
 {
         int cpu, ret, max = PERF_TYPE_MAX;
 
         mutex_lock(&pmus_lock);
         ret = -ENOMEM;
         pmu->pmu_disable_count = alloc_percpu(int);
         if (!pmu->pmu_disable_count)
                 goto unlock;
 
         pmu->type = -1;
         if (WARN_ONCE(!name, "Can not register anonymous pmu.\n")) {
                 ret = -EINVAL;
                 goto free_pdc;
         }
 
         pmu->name = name;
 
         if (type >= 0)
                 max = type;
 
         ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL);
         if (ret < 0)
                 goto free_pdc;
 
         WARN_ON(type >= 0 && ret != type);
 
         type = ret;
         pmu->type = type;
 
         if (pmu_bus_running && !pmu->dev) {
                 ret = pmu_dev_alloc(pmu);
                 if (ret)
                         goto free_idr;
         }
 
         ret = -ENOMEM;
         pmu->cpu_pmu_context = alloc_percpu(struct perf_cpu_pmu_context);
         if (!pmu->cpu_pmu_context)
                 goto free_dev;
 
         for_each_possible_cpu(cpu) {
                 struct perf_cpu_pmu_context *cpc;
 
                 cpc = per_cpu_ptr(pmu->cpu_pmu_context, cpu);
                 __perf_init_event_pmu_context(&cpc->epc, pmu);
                 __perf_mux_hrtimer_init(cpc, cpu);
         }
 
         if (!pmu->start_txn) {
                 if (pmu->pmu_enable) {
                         /*
                          * If we have pmu_enable/pmu_disable calls, install
                          * transaction stubs that use that to try and batch
                          * hardware accesses.
                          */
                         pmu->start_txn  = perf_pmu_start_txn;
                         pmu->commit_txn = perf_pmu_commit_txn;
                         pmu->cancel_txn = perf_pmu_cancel_txn;
                 } else {
                         pmu->start_txn  = perf_pmu_nop_txn;
                         pmu->commit_txn = perf_pmu_nop_int;
                         pmu->cancel_txn = perf_pmu_nop_void;
                 }
         }
 
         if (!pmu->pmu_enable) {
                 pmu->pmu_enable  = perf_pmu_nop_void;
                 pmu->pmu_disable = perf_pmu_nop_void;
         }
 
         if (!pmu->check_period)
                 pmu->check_period = perf_event_nop_int;
 
         if (!pmu->event_idx)
                 pmu->event_idx = perf_event_idx_default;
 
         list_add_rcu(&pmu->entry, &pmus);
         atomic_set(&pmu->exclusive_cnt, 0);
         ret = 0;
 unlock:
         mutex_unlock(&pmus_lock);
 
         return ret;
 
 free_dev:
         if (pmu->dev && pmu->dev != PMU_NULL_DEV) {
                 device_del(pmu->dev);
                 put_device(pmu->dev);
         }
 
 free_idr:
         idr_remove(&pmu_idr, pmu->type);
 
 free_pdc:
         free_percpu(pmu->pmu_disable_count);
         goto unlock;
 }
 EXPORT_SYMBOL_GPL(perf_pmu_register);
 
 void perf_pmu_unregister(struct pmu *pmu)
 {
         mutex_lock(&pmus_lock);
         list_del_rcu(&pmu->entry);
 
         /*
          * We dereference the pmu list under both SRCU and regular RCU, so
          * synchronize against both of those.
          */
         synchronize_srcu(&pmus_srcu);
         synchronize_rcu();
 
         free_percpu(pmu->pmu_disable_count);
         idr_remove(&pmu_idr, pmu->type);
         if (pmu_bus_running && pmu->dev && pmu->dev != PMU_NULL_DEV) {
                 if (pmu->nr_addr_filters)
                         device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
                 device_del(pmu->dev);
                 put_device(pmu->dev);
         }
         free_pmu_context(pmu);
         mutex_unlock(&pmus_lock);
 }
 EXPORT_SYMBOL_GPL(perf_pmu_unregister);
 
 static inline bool has_extended_regs(struct perf_event *event)
 {
         return (event->attr.sample_regs_user & PERF_REG_EXTENDED_MASK) ||
                (event->attr.sample_regs_intr & PERF_REG_EXTENDED_MASK);
 }
 
 static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
 {
         struct perf_event_context *ctx = NULL;
         int ret;
 
         if (!try_module_get(pmu->module))
                 return -ENODEV;
 
         /*
          * A number of pmu->event_init() methods iterate the sibling_list to,
          * for example, validate if the group fits on the PMU. Therefore,
          * if this is a sibling event, acquire the ctx->mutex to protect
          * the sibling_list.
          */
         if (event->group_leader != event && pmu->task_ctx_nr != perf_sw_context) {
                 /*
                  * This ctx->mutex can nest when we're called through
                  * inheritance. See the perf_event_ctx_lock_nested() comment.
                  */
                 ctx = perf_event_ctx_lock_nested(event->group_leader,
                                                  SINGLE_DEPTH_NESTING);
                 BUG_ON(!ctx);
         }
 
         event->pmu = pmu;
         ret = pmu->event_init(event);
 
         if (ctx)
                 perf_event_ctx_unlock(event->group_leader, ctx);
 
         if (!ret) {
                 if (!(pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS) &&
                     has_extended_regs(event))
                         ret = -EOPNOTSUPP;
 
                 if (pmu->capabilities & PERF_PMU_CAP_NO_EXCLUDE &&
                     event_has_any_exclude_flag(event))
                         ret = -EINVAL;
 
                 if (ret && event->destroy)
                         event->destroy(event);
         }
 
         if (ret)
                 module_put(pmu->module);
 
         return ret;
 }
 
 static struct pmu *perf_init_event(struct perf_event *event)
 {
         bool extended_type = false;
         int idx, type, ret;
         struct pmu *pmu;
 
         idx = srcu_read_lock(&pmus_srcu);
 
         /*
          * Save original type before calling pmu->event_init() since certain
          * pmus overwrites event->attr.type to forward event to another pmu.
          */
         event->orig_type = event->attr.type;
 
         /* Try parent's PMU first: */
         if (event->parent && event->parent->pmu) {
                 pmu = event->parent->pmu;
                 ret = perf_try_init_event(pmu, event);
                 if (!ret)
                         goto unlock;
         }
 
         /*
          * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE
          * are often aliases for PERF_TYPE_RAW.
          */
         type = event->attr.type;
         if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_HW_CACHE) {
                 type = event->attr.config >> PERF_PMU_TYPE_SHIFT;
                 if (!type) {
                         type = PERF_TYPE_RAW;
                 } else {
                         extended_type = true;
                         event->attr.config &= PERF_HW_EVENT_MASK;
                 }
         }
 
 again:
         rcu_read_lock();
         pmu = idr_find(&pmu_idr, type);
         rcu_read_unlock();
         if (pmu) {
                 if (event->attr.type != type && type != PERF_TYPE_RAW &&
                     !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
                         goto fail;
 
                 ret = perf_try_init_event(pmu, event);
                 if (ret == -ENOENT && event->attr.type != type && !extended_type) {
                         type = event->attr.type;
                         goto again;
                 }
 
                 if (ret)
                         pmu = ERR_PTR(ret);
 
                 goto unlock;
         }
 
         list_for_each_entry_rcu(pmu, &pmus, entry, lockdep_is_held(&pmus_srcu)) {
                 ret = perf_try_init_event(pmu, event);
                 if (!ret)
                         goto unlock;
 
                 if (ret != -ENOENT) {
                         pmu = ERR_PTR(ret);
                         goto unlock;
                 }
         }
 fail:
         pmu = ERR_PTR(-ENOENT);
 unlock:
         srcu_read_unlock(&pmus_srcu, idx);
 
         return pmu;
 }
 
 static void attach_sb_event(struct perf_event *event)
 {
         struct pmu_event_list *pel = per_cpu_ptr(&pmu_sb_events, event->cpu);
 
         raw_spin_lock(&pel->lock);
         list_add_rcu(&event->sb_list, &pel->list);
         raw_spin_unlock(&pel->lock);
 }
 
 /*
  * We keep a list of all !task (and therefore per-cpu) events
  * that need to receive side-band records.
  *
  * This avoids having to scan all the various PMU per-cpu contexts
  * looking for them.
  */
 static void account_pmu_sb_event(struct perf_event *event)
 {
         if (is_sb_event(event))
                 attach_sb_event(event);
 }
 
 /* Freq events need the tick to stay alive (see perf_event_task_tick). */
 static void account_freq_event_nohz(void)
 {
 #ifdef CONFIG_NO_HZ_FULL
         /* Lock so we don't race with concurrent unaccount */
         spin_lock(&nr_freq_lock);
         if (atomic_inc_return(&nr_freq_events) == 1)
                 tick_nohz_dep_set(TICK_DEP_BIT_PERF_EVENTS);
         spin_unlock(&nr_freq_lock);
 #endif
 }
 
 static void account_freq_event(void)
 {
         if (tick_nohz_full_enabled())
                 account_freq_event_nohz();
         else
                 atomic_inc(&nr_freq_events);
 }
 
 
 static void account_event(struct perf_event *event)
 {
         bool inc = false;
 
         if (event->parent)
                 return;
 
         if (event->attach_state & (PERF_ATTACH_TASK | PERF_ATTACH_SCHED_CB))
                 inc = true;
         if (event->attr.mmap || event->attr.mmap_data)
                 atomic_inc(&nr_mmap_events);
         if (event->attr.build_id)
                 atomic_inc(&nr_build_id_events);
         if (event->attr.comm)
                 atomic_inc(&nr_comm_events);
         if (event->attr.namespaces)
                 atomic_inc(&nr_namespaces_events);
         if (event->attr.cgroup)
                 atomic_inc(&nr_cgroup_events);
         if (event->attr.task)
                 atomic_inc(&nr_task_events);
         if (event->attr.freq)
                 account_freq_event();
         if (event->attr.context_switch) {
                 atomic_inc(&nr_switch_events);
                 inc = true;
         }
         if (has_branch_stack(event))
                 inc = true;
         if (is_cgroup_event(event))
                 inc = true;
         if (event->attr.ksymbol)
                 atomic_inc(&nr_ksymbol_events);
         if (event->attr.bpf_event)
                 atomic_inc(&nr_bpf_events);
         if (event->attr.text_poke)
                 atomic_inc(&nr_text_poke_events);
 
         if (inc) {
                 /*
                  * We need the mutex here because static_branch_enable()
                  * must complete *before* the perf_sched_count increment
                  * becomes visible.
                  */
                 if (atomic_inc_not_zero(&perf_sched_count))
                         goto enabled;
 
                 mutex_lock(&perf_sched_mutex);
                 if (!atomic_read(&perf_sched_count)) {
                         static_branch_enable(&perf_sched_events);
                         /*
                          * Guarantee that all CPUs observe they key change and
                          * call the perf scheduling hooks before proceeding to
                          * install events that need them.
                          */
                         synchronize_rcu();
                 }
                 /*
                  * Now that we have waited for the sync_sched(), allow further
                  * increments to by-pass the mutex.
                  */
                 atomic_inc(&perf_sched_count);
                 mutex_unlock(&perf_sched_mutex);
         }
 enabled:
 
         account_pmu_sb_event(event);
 }
 
 /*
  * Allocate and initialize an event structure
  */
 static struct perf_event *
 perf_event_alloc(struct perf_event_attr *attr, int cpu,
                  struct task_struct *task,
                  struct perf_event *group_leader,
                  struct perf_event *parent_event,
                  perf_overflow_handler_t overflow_handler,
                  void *context, int cgroup_fd)
 {
         struct pmu *pmu;
         struct perf_event *event;
         struct hw_perf_event *hwc;
         long err = -EINVAL;
         int node;
 
         if ((unsigned)cpu >= nr_cpu_ids) {
                 if (!task || cpu != -1)
                         return ERR_PTR(-EINVAL);
         }
         if (attr->sigtrap && !task) {
                 /* Requires a task: avoid signalling random tasks. */
                 return ERR_PTR(-EINVAL);
         }
 
         node = (cpu >= 0) ? cpu_to_node(cpu) : -1;
         event = kmem_cache_alloc_node(perf_event_cache, GFP_KERNEL | __GFP_ZERO,
                                       node);
         if (!event)
                 return ERR_PTR(-ENOMEM);
 
         /*
          * Single events are their own group leaders, with an
          * empty sibling list:
          */
         if (!group_leader)
                 group_leader = event;
 
         mutex_init(&event->child_mutex);
         INIT_LIST_HEAD(&event->child_list);
 
         INIT_LIST_HEAD(&event->event_entry);
         INIT_LIST_HEAD(&event->sibling_list);
         INIT_LIST_HEAD(&event->active_list);
         init_event_group(event);
         INIT_LIST_HEAD(&event->rb_entry);
         INIT_LIST_HEAD(&event->active_entry);
         INIT_LIST_HEAD(&event->addr_filters.list);
         INIT_HLIST_NODE(&event->hlist_entry);
 
 
         init_waitqueue_head(&event->waitq);
         init_irq_work(&event->pending_irq, perf_pending_irq);
         event->pending_disable_irq = IRQ_WORK_INIT_HARD(perf_pending_disable);
         init_task_work(&event->pending_task, perf_pending_task);
         rcuwait_init(&event->pending_work_wait);
 
         mutex_init(&event->mmap_mutex);
         raw_spin_lock_init(&event->addr_filters.lock);
 
         atomic_long_set(&event->refcount, 1);
         event->cpu              = cpu;
         event->attr             = *attr;
         event->group_leader     = group_leader;
         event->pmu              = NULL;
         event->oncpu            = -1;
 
         event->parent           = parent_event;
 
         event->ns               = get_pid_ns(task_active_pid_ns(current));
         event->id               = atomic64_inc_return(&perf_event_id);
 
         event->state            = PERF_EVENT_STATE_INACTIVE;
 
         if (parent_event)
                 event->event_caps = parent_event->event_caps;
 
         if (task) {
                 event->attach_state = PERF_ATTACH_TASK;
                 /*
                  * XXX pmu::event_init needs to know what task to account to
                  * and we cannot use the ctx information because we need the
                  * pmu before we get a ctx.
                  */
                 event->hw.target = get_task_struct(task);
         }
 
         event->clock = &local_clock;
         if (parent_event)
                 event->clock = parent_event->clock;
 
         if (!overflow_handler && parent_event) {
                 overflow_handler = parent_event->overflow_handler;
                 context = parent_event->overflow_handler_context;
 #if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_EVENT_TRACING)
                 if (parent_event->prog) {
                         struct bpf_prog *prog = parent_event->prog;
 
                         bpf_prog_inc(prog);
                         event->prog = prog;
                 }
 #endif
         }
 
         if (overflow_handler) {
                 event->overflow_handler = overflow_handler;
                 event->overflow_handler_context = context;
         } else if (is_write_backward(event)){
                 event->overflow_handler = perf_event_output_backward;
                 event->overflow_handler_context = NULL;
         } else {
                 event->overflow_handler = perf_event_output_forward;
                 event->overflow_handler_context = NULL;
         }
 
         perf_event__state_init(event);
 
         pmu = NULL;
 
         hwc = &event->hw;
         hwc->sample_period = attr->sample_period;
         if (attr->freq && attr->sample_freq)
                 hwc->sample_period = 1;
         hwc->last_period = hwc->sample_period;
 
         local64_set(&hwc->period_left, hwc->sample_period);
 
         /*
          * We currently do not support PERF_SAMPLE_READ on inherited events.
          * See perf_output_read().
          */
         if (attr->inherit && (attr->sample_type & PERF_SAMPLE_READ))
                 goto err_ns;
 
         if (!has_branch_stack(event))
                 event->attr.branch_sample_type = 0;
 
         pmu = perf_init_event(event);
         if (IS_ERR(pmu)) {
                 err = PTR_ERR(pmu);
                 goto err_ns;
         }
 
         /*
          * Disallow uncore-task events. Similarly, disallow uncore-cgroup
          * events (they don't make sense as the cgroup will be different
          * on other CPUs in the uncore mask).
          */
         if (pmu->task_ctx_nr == perf_invalid_context && (task || cgroup_fd != -1)) {
                 err = -EINVAL;
                 goto err_pmu;
         }
 
         if (event->attr.aux_output &&
             !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) {
                 err = -EOPNOTSUPP;
                 goto err_pmu;
         }
 
         if (cgroup_fd != -1) {
                 err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
                 if (err)
                         goto err_pmu;
         }
 
         err = exclusive_event_init(event);
         if (err)
                 goto err_pmu;
 
         if (has_addr_filter(event)) {
                 event->addr_filter_ranges = kcalloc(pmu->nr_addr_filters,
                                                     sizeof(struct perf_addr_filter_range),
                                                     GFP_KERNEL);
                 if (!event->addr_filter_ranges) {
                         err = -ENOMEM;
                         goto err_per_task;
                 }
 
                 /*
                  * Clone the parent's vma offsets: they are valid until exec()
                  * even if the mm is not shared with the parent.
                  */
                 if (event->parent) {
                         struct perf_addr_filters_head *ifh = perf_event_addr_filters(event);
 
                         raw_spin_lock_irq(&ifh->lock);
                         memcpy(event->addr_filter_ranges,
                                event->parent->addr_filter_ranges,
                                pmu->nr_addr_filters * sizeof(struct perf_addr_filter_range));
                         raw_spin_unlock_irq(&ifh->lock);
                 }
 
                 /* force hw sync on the address filters */
                 event->addr_filters_gen = 1;
         }
 
         if (!event->parent) {
                 if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
                         err = get_callchain_buffers(attr->sample_max_stack);
                         if (err)
                                 goto err_addr_filters;
                 }
         }
 
         err = security_perf_event_alloc(event);
         if (err)
                 goto err_callchain_buffer;
 
         /* symmetric to unaccount_event() in _free_event() */
         account_event(event);
 
         return event;
 
 err_callchain_buffer:
         if (!event->parent) {
                 if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)
                         put_callchain_buffers();
         }
 err_addr_filters:
         kfree(event->addr_filter_ranges);
 
 err_per_task:
         exclusive_event_destroy(event);
 
 err_pmu:
         if (is_cgroup_event(event))
                 perf_detach_cgroup(event);
         if (event->destroy)
                 event->destroy(event);
         module_put(pmu->module);
 err_ns:
         if (event->hw.target)
                 put_task_struct(event->hw.target);
         call_rcu(&event->rcu_head, free_event_rcu);
 
         return ERR_PTR(err);
 }
 
 static int perf_copy_attr(struct perf_event_attr __user *uattr,
                           struct perf_event_attr *attr)
 {
         u32 size;
         int ret;
 
         /* Zero the full structure, so that a short copy will be nice. */
         memset(attr, 0, sizeof(*attr));
 
         ret = get_user(size, &uattr->size);
         if (ret)
                 return ret;
 
         /* ABI compatibility quirk: */
         if (!size)
                 size = PERF_ATTR_SIZE_VER0;
         if (size < PERF_ATTR_SIZE_VER0 || size > PAGE_SIZE)
                 goto err_size;
 
         ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);
         if (ret) {
                 if (ret == -E2BIG)
                         goto err_size;
                 return ret;
         }
 
         attr->size = size;
 
         if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3)
                 return -EINVAL;
 
         if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
                 return -EINVAL;
 
         if (attr->read_format & ~(PERF_FORMAT_MAX-1))
                 return -EINVAL;
 
         if (attr->sample_type & PERF_SAMPLE_BRANCH_STACK) {
                 u64 mask = attr->branch_sample_type;
 
                 /* only using defined bits */
                 if (mask & ~(PERF_SAMPLE_BRANCH_MAX-1))
                         return -EINVAL;
 
                 /* at least one branch bit must be set */
                 if (!(mask & ~PERF_SAMPLE_BRANCH_PLM_ALL))
                         return -EINVAL;
 
                 /* propagate priv level, when not set for branch */
                 if (!(mask & PERF_SAMPLE_BRANCH_PLM_ALL)) {
 
                         /* exclude_kernel checked on syscall entry */
                         if (!attr->exclude_kernel)
                                 mask |= PERF_SAMPLE_BRANCH_KERNEL;
 
                         if (!attr->exclude_user)
                                 mask |= PERF_SAMPLE_BRANCH_USER;
 
                         if (!attr->exclude_hv)
                                 mask |= PERF_SAMPLE_BRANCH_HV;
                         /*
                          * adjust user setting (for HW filter setup)
                          */
                         attr->branch_sample_type = mask;
                 }
                 /* privileged levels capture (kernel, hv): check permissions */
                 if (mask & PERF_SAMPLE_BRANCH_PERM_PLM) {
                         ret = perf_allow_kernel(attr);
                         if (ret)
                                 return ret;
                 }
         }
 
         if (attr->sample_type & PERF_SAMPLE_REGS_USER) {
                 ret = perf_reg_validate(attr->sample_regs_user);
                 if (ret)
                         return ret;
         }
 
         if (attr->sample_type & PERF_SAMPLE_STACK_USER) {
                 if (!arch_perf_have_user_stack_dump())
                         return -ENOSYS;
 
                 /*
                  * We have __u32 type for the size, but so far
                  * we can only use __u16 as maximum due to the
                  * __u16 sample size limit.
                  */
                 if (attr->sample_stack_user >= USHRT_MAX)
                         return -EINVAL;
                 else if (!IS_ALIGNED(attr->sample_stack_user, sizeof(u64)))
                         return -EINVAL;
         }
 
         if (!attr->sample_max_stack)
                 attr->sample_max_stack = sysctl_perf_event_max_stack;
 
         if (attr->sample_type & PERF_SAMPLE_REGS_INTR)
                 ret = perf_reg_validate(attr->sample_regs_intr);
 
 #ifndef CONFIG_CGROUP_PERF
         if (attr->sample_type & PERF_SAMPLE_CGROUP)
                 return -EINVAL;
 #endif
         if ((attr->sample_type & PERF_SAMPLE_WEIGHT) &&
             (attr->sample_type & PERF_SAMPLE_WEIGHT_STRUCT))
                 return -EINVAL;
 
         if (!attr->inherit && attr->inherit_thread)
                 return -EINVAL;
 
         if (attr->remove_on_exec && attr->enable_on_exec)
                 return -EINVAL;
 
         if (attr->sigtrap && !attr->remove_on_exec)
                 return -EINVAL;
 
 out:
         return ret;
 
 err_size:
         put_user(sizeof(*attr), &uattr->size);
         ret = -E2BIG;
         goto out;
 }
 
 static void mutex_lock_double(struct mutex *a, struct mutex *b)
 {
         if (b < a)
                 swap(a, b);
 
         mutex_lock(a);
         mutex_lock_nested(b, SINGLE_DEPTH_NESTING);
 }
 
 static int
 perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
 {
         struct perf_buffer *rb = NULL;
         int ret = -EINVAL;
 
         if (!output_event) {
                 mutex_lock(&event->mmap_mutex);
                 goto set;
         }
 
         /* don't allow circular references */
         if (event == output_event)
                 goto out;
 
         /*
          * Don't allow cross-cpu buffers
          */
         if (output_event->cpu != event->cpu)
                 goto out;
 
         /*
          * If its not a per-cpu rb, it must be the same task.
          */
         if (output_event->cpu == -1 && output_event->hw.target != event->hw.target)
                 goto out;
 
         /*
          * Mixing clocks in the same buffer is trouble you don't need.
          */
         if (output_event->clock != event->clock)
                 goto out;
 
         /*
          * Either writing ring buffer from beginning or from end.
          * Mixing is not allowed.
          */
         if (is_write_backward(output_event) != is_write_backward(event))
                 goto out;
 
         /*
          * If both events generate aux data, they must be on the same PMU
          */
         if (has_aux(event) && has_aux(output_event) &&
             event->pmu != output_event->pmu)
                 goto out;
 
         /*
          * Hold both mmap_mutex to serialize against perf_mmap_close().  Since
          * output_event is already on rb->event_list, and the list iteration
          * restarts after every removal, it is guaranteed this new event is
          * observed *OR* if output_event is already removed, it's guaranteed we
          * observe !rb->mmap_count.
          */
         mutex_lock_double(&event->mmap_mutex, &output_event->mmap_mutex);
 set:
         /* Can't redirect output if we've got an active mmap() */
         if (atomic_read(&event->mmap_count))
                 goto unlock;
 
         if (output_event) {
                 /* get the rb we want to redirect to */
                 rb = ring_buffer_get(output_event);
                 if (!rb)
                         goto unlock;
 
                 /* did we race against perf_mmap_close() */
                 if (!atomic_read(&rb->mmap_count)) {
                         ring_buffer_put(rb);
                         goto unlock;
                 }
         }
 
         ring_buffer_attach(event, rb);
 
         ret = 0;
 unlock:
         mutex_unlock(&event->mmap_mutex);
         if (output_event)
                 mutex_unlock(&output_event->mmap_mutex);
 
 out:
         return ret;
 }
 
 static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
 {
         bool nmi_safe = false;
 
         switch (clk_id) {
         case CLOCK_MONOTONIC:
                 event->clock = &ktime_get_mono_fast_ns;
                 nmi_safe = true;
                 break;
 
         case CLOCK_MONOTONIC_RAW:
                 event->clock = &ktime_get_raw_fast_ns;
                 nmi_safe = true;
                 break;
 
         case CLOCK_REALTIME:
                 event->clock = &ktime_get_real_ns;
                 break;
 
         case CLOCK_BOOTTIME:
                 event->clock = &ktime_get_boottime_ns;
                 break;
 
         case CLOCK_TAI:
                 event->clock = &ktime_get_clocktai_ns;
                 break;
 
         default:
                 return -EINVAL;
         }
 
         if (!nmi_safe && !(event->pmu->capabilities & PERF_PMU_CAP_NO_NMI))
                 return -EINVAL;
 
         return 0;
 }
 
 static bool
 perf_check_permission(struct perf_event_attr *attr, struct task_struct *task)
 {
         unsigned int ptrace_mode = PTRACE_MODE_READ_REALCREDS;
         bool is_capable = perfmon_capable();
 
         if (attr->sigtrap) {
                 /*
                  * perf_event_attr::sigtrap sends signals to the other task.
                  * Require the current task to also have CAP_KILL.
                  */
                 rcu_read_lock();
                 is_capable &= ns_capable(__task_cred(task)->user_ns, CAP_KILL);
                 rcu_read_unlock();
 
                 /*
                  * If the required capabilities aren't available, checks for
                  * ptrace permissions: upgrade to ATTACH, since sending signals
                  * can effectively change the target task.
                  */
                 ptrace_mode = PTRACE_MODE_ATTACH_REALCREDS;
         }
 
         /*
          * Preserve ptrace permission check for backwards compatibility. The
          * ptrace check also includes checks that the current task and other
          * task have matching uids, and is therefore not done here explicitly.
          */
         return is_capable || ptrace_may_access(task, ptrace_mode);
 }
 
 /**
  * sys_perf_event_open - open a performance event, associate it to a task/cpu
  *
  * @attr_uptr:  event_id type attributes for monitoring/sampling
  * @pid:                target pid
  * @cpu:                target cpu
  * @group_fd:           group leader event fd
  * @flags:              perf event open flags
  */
 SYSCALL_DEFINE5(perf_event_open,
                 struct perf_event_attr __user *, attr_uptr,
                 pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
 {
         struct perf_event *group_leader = NULL, *output_event = NULL;
         struct perf_event_pmu_context *pmu_ctx;
         struct perf_event *event, *sibling;
         struct perf_event_attr attr;
         struct perf_event_context *ctx;
         struct file *event_file = NULL;
         struct fd group = {NULL, 0};
         struct task_struct *task = NULL;
         struct pmu *pmu;
         int event_fd;
         int move_group = 0;
         int err;
         int f_flags = O_RDWR;
         int cgroup_fd = -1;
 
         /* for future expandability... */
         if (flags & ~PERF_FLAG_ALL)
                 return -EINVAL;
 
         err = perf_copy_attr(attr_uptr, &attr);
         if (err)
                 return err;
 
         /* Do we allow access to perf_event_open(2) ? */
         err = security_perf_event_open(&attr, PERF_SECURITY_OPEN);
         if (err)
                 return err;
 
         if (!attr.exclude_kernel) {
                 err = perf_allow_kernel(&attr);
                 if (err)
                         return err;
         }
 
         if (attr.namespaces) {
                 if (!perfmon_capable())
                         return -EACCES;
         }
 
         if (attr.freq) {
                 if (attr.sample_freq > sysctl_perf_event_sample_rate)
                         return -EINVAL;
         } else {
                 if (attr.sample_period & (1ULL << 63))
                         return -EINVAL;
         }
 
         /* Only privileged users can get physical addresses */
         if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR)) {
                 err = perf_allow_kernel(&attr);
                 if (err)
                         return err;
         }
 
         /* REGS_INTR can leak data, lockdown must prevent this */
         if (attr.sample_type & PERF_SAMPLE_REGS_INTR) {
                 err = security_locked_down(LOCKDOWN_PERF);
                 if (err)
                         return err;
         }
 
         /*
          * In cgroup mode, the pid argument is used to pass the fd
          * opened to the cgroup directory in cgroupfs. The cpu argument
          * designates the cpu on which to monitor threads from that
          * cgroup.
          */
         if ((flags & PERF_FLAG_PID_CGROUP) && (pid == -1 || cpu == -1))
                 return -EINVAL;
 
         if (flags & PERF_FLAG_FD_CLOEXEC)
                 f_flags |= O_CLOEXEC;
 
         event_fd = get_unused_fd_flags(f_flags);
         if (event_fd < 0)
                 return event_fd;
 
         if (group_fd != -1) {
                 err = perf_fget_light(group_fd, &group);
                 if (err)
                         goto err_fd;
                 group_leader = group.file->private_data;
                 if (flags & PERF_FLAG_FD_OUTPUT)
                         output_event = group_leader;
                 if (flags & PERF_FLAG_FD_NO_GROUP)
                         group_leader = NULL;
         }
 
         if (pid != -1 && !(flags & PERF_FLAG_PID_CGROUP)) {
                 task = find_lively_task_by_vpid(pid);
                 if (IS_ERR(task)) {
                         err = PTR_ERR(task);
                         goto err_group_fd;
                 }
         }
 
         if (task && group_leader &&
             group_leader->attr.inherit != attr.inherit) {
                 err = -EINVAL;
                 goto err_task;
         }
 
         if (flags & PERF_FLAG_PID_CGROUP)
                 cgroup_fd = pid;
 
         event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
                                  NULL, NULL, cgroup_fd);
         if (IS_ERR(event)) {
                 err = PTR_ERR(event);
                 goto err_task;
         }
 
         if (is_sampling_event(event)) {
                 if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
                         err = -EOPNOTSUPP;
                         goto err_alloc;
                 }
         }
 
         /*
          * Special case software events and allow them to be part of
          * any hardware group.
          */
         pmu = event->pmu;
 
         if (attr.use_clockid) {
                 err = perf_event_set_clock(event, attr.clockid);
                 if (err)
                         goto err_alloc;
         }
 
         if (pmu->task_ctx_nr == perf_sw_context)
                 event->event_caps |= PERF_EV_CAP_SOFTWARE;
 
         if (task) {
                 err = down_read_interruptible(&task->signal->exec_update_lock);
                 if (err)
                         goto err_alloc;
 
                 /*
                  * We must hold exec_update_lock across this and any potential
                  * perf_install_in_context() call for this new event to
                  * serialize against exec() altering our credentials (and the
                  * perf_event_exit_task() that could imply).
                  */
                 err = -EACCES;
                 if (!perf_check_permission(&attr, task))
                         goto err_cred;
         }
 
         /*
          * Get the target context (task or percpu):
          */
         ctx = find_get_context(task, event);
         if (IS_ERR(ctx)) {
                 err = PTR_ERR(ctx);
                 goto err_cred;
         }
 
         mutex_lock(&ctx->mutex);
 
         if (ctx->task == TASK_TOMBSTONE) {
                 err = -ESRCH;
                 goto err_locked;
         }
 
         if (!task) {
                 /*
                  * Check if the @cpu we're creating an event for is online.
                  *
                  * We use the perf_cpu_context::ctx::mutex to serialize against
                  * the hotplug notifiers. See perf_event_{init,exit}_cpu().
                  */
                 struct perf_cpu_context *cpuctx = per_cpu_ptr(&perf_cpu_context, event->cpu);
 
                 if (!cpuctx->online) {
                         err = -ENODEV;
                         goto err_locked;
                 }
         }
 
         if (group_leader) {
                 err = -EINVAL;
 
                 /*
                  * Do not allow a recursive hierarchy (this new sibling
                  * becoming part of another group-sibling):
                  */
                 if (group_leader->group_leader != group_leader)
                         goto err_locked;
 
                 /* All events in a group should have the same clock */
                 if (group_leader->clock != event->clock)
                         goto err_locked;
 
                 /*
                  * Make sure we're both events for the same CPU;
                  * grouping events for different CPUs is broken; since
                  * you can never concurrently schedule them anyhow.
                  */
                 if (group_leader->cpu != event->cpu)
                         goto err_locked;
 
                 /*
                  * Make sure we're both on the same context; either task or cpu.
                  */
                 if (group_leader->ctx != ctx)
                         goto err_locked;
 
                 /*
                  * Only a group leader can be exclusive or pinned
                  */
                 if (attr.exclusive || attr.pinned)
                         goto err_locked;
 
                 if (is_software_event(event) &&
                     !in_software_context(group_leader)) {
                         /*
                          * If the event is a sw event, but the group_leader
                          * is on hw context.
                          *
                          * Allow the addition of software events to hw
                          * groups, this is safe because software events
                          * never fail to schedule.
                          *
                          * Note the comment that goes with struct
                          * perf_event_pmu_context.
                          */
                         pmu = group_leader->pmu_ctx->pmu;
                 } else if (!is_software_event(event)) {
                         if (is_software_event(group_leader) &&
                             (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
                                 /*
                                  * In case the group is a pure software group, and we
                                  * try to add a hardware event, move the whole group to
                                  * the hardware context.
                                  */
                                 move_group = 1;
                         }
 
                         /* Don't allow group of multiple hw events from different pmus */
                         if (!in_software_context(group_leader) &&
                             group_leader->pmu_ctx->pmu != pmu)
                                 goto err_locked;
                 }
         }
 
         /*
          * Now that we're certain of the pmu; find the pmu_ctx.
          */
         pmu_ctx = find_get_pmu_context(pmu, ctx, event);
         if (IS_ERR(pmu_ctx)) {
                 err = PTR_ERR(pmu_ctx);
                 goto err_locked;
         }
         event->pmu_ctx = pmu_ctx;
 
         if (output_event) {
                 err = perf_event_set_output(event, output_event);
                 if (err)
                         goto err_context;
         }
 
         if (!perf_event_validate_size(event)) {
                 err = -E2BIG;
                 goto err_context;
         }
 
         if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) {
                 err = -EINVAL;
                 goto err_context;
         }
 
         /*
          * Must be under the same ctx::mutex as perf_install_in_context(),
          * because we need to serialize with concurrent event creation.
          */
         if (!exclusive_event_installable(event, ctx)) {
                 err = -EBUSY;
                 goto err_context;
         }
 
         WARN_ON_ONCE(ctx->parent_ctx);
 
         event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, f_flags);
         if (IS_ERR(event_file)) {
                 err = PTR_ERR(event_file);
                 event_file = NULL;
                 goto err_context;
         }
 
         /*
          * This is the point on no return; we cannot fail hereafter. This is
          * where we start modifying current state.
          */
 
         if (move_group) {
                 perf_remove_from_context(group_leader, 0);
                 put_pmu_ctx(group_leader->pmu_ctx);
 
                 for_each_sibling_event(sibling, group_leader) {
                         perf_remove_from_context(sibling, 0);
                         put_pmu_ctx(sibling->pmu_ctx);
                 }
 
                 /*
                  * Install the group siblings before the group leader.
                  *
                  * Because a group leader will try and install the entire group
                  * (through the sibling list, which is still in-tact), we can
                  * end up with siblings installed in the wrong context.
                  *
                  * By installing siblings first we NO-OP because they're not
                  * reachable through the group lists.
                  */
                 for_each_sibling_event(sibling, group_leader) {
                         sibling->pmu_ctx = pmu_ctx;
                         get_pmu_ctx(pmu_ctx);
                         perf_event__state_init(sibling);
                         perf_install_in_context(ctx, sibling, sibling->cpu);
                 }
 
                 /*
                  * Removing from the context ends up with disabled
                  * event. What we want here is event in the initial
                  * startup state, ready to be add into new context.
                  */
                 group_leader->pmu_ctx = pmu_ctx;
                 get_pmu_ctx(pmu_ctx);
                 perf_event__state_init(group_leader);
                 perf_install_in_context(ctx, group_leader, group_leader->cpu);
         }
 
         /*
          * Precalculate sample_data sizes; do while holding ctx::mutex such
          * that we're serialized against further additions and before
          * perf_install_in_context() which is the point the event is active and
          * can use these values.
          */
         perf_event__header_size(event);
         perf_event__id_header_size(event);
 
         event->owner = current;
 
         perf_install_in_context(ctx, event, event->cpu);
         perf_unpin_context(ctx);
 
         mutex_unlock(&ctx->mutex);
 
         if (task) {
                 up_read(&task->signal->exec_update_lock);
                 put_task_struct(task);
         }
 
         mutex_lock(&current->perf_event_mutex);
         list_add_tail(&event->owner_entry, &current->perf_event_list);
         mutex_unlock(&current->perf_event_mutex);
 
         /*
          * Drop the reference on the group_event after placing the
          * new event on the sibling_list. This ensures destruction
          * of the group leader will find the pointer to itself in
          * perf_group_detach().
          */
         fdput(group);
         fd_install(event_fd, event_file);
         return event_fd;
 
 err_context:
         put_pmu_ctx(event->pmu_ctx);
         event->pmu_ctx = NULL; /* _free_event() */
 err_locked:
         mutex_unlock(&ctx->mutex);
         perf_unpin_context(ctx);
         put_ctx(ctx);
 err_cred:
         if (task)
                 up_read(&task->signal->exec_update_lock);
 err_alloc:
         free_event(event);
 err_task:
         if (task)
                 put_task_struct(task);
 err_group_fd:
         fdput(group);
 err_fd:
         put_unused_fd(event_fd);
         return err;
 }
 
 /**
  * perf_event_create_kernel_counter
  *
  * @attr: attributes of the counter to create
  * @cpu: cpu in which the counter is bound
  * @task: task to profile (NULL for percpu)
  * @overflow_handler: callback to trigger when we hit the event
  * @context: context data could be used in overflow_handler callback
  */
 struct perf_event *
 perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
                                  struct task_struct *task,
                                  perf_overflow_handler_t overflow_handler,
                                  void *context)
 {
         struct perf_event_pmu_context *pmu_ctx;
         struct perf_event_context *ctx;
         struct perf_event *event;
         struct pmu *pmu;
         int err;
 
         /*
          * Grouping is not supported for kernel events, neither is 'AUX',
          * make sure the caller's intentions are adjusted.
          */
         if (attr->aux_output)
                 return ERR_PTR(-EINVAL);
 
         event = perf_event_alloc(attr, cpu, task, NULL, NULL,
                                  overflow_handler, context, -1);
         if (IS_ERR(event)) {
                 err = PTR_ERR(event);
                 goto err;
         }
 
         /* Mark owner so we could distinguish it from user events. */
         event->owner = TASK_TOMBSTONE;
         pmu = event->pmu;
 
         if (pmu->task_ctx_nr == perf_sw_context)
                 event->event_caps |= PERF_EV_CAP_SOFTWARE;
 
         /*
          * Get the target context (task or percpu):
          */
         ctx = find_get_context(task, event);
         if (IS_ERR(ctx)) {
                 err = PTR_ERR(ctx);
                 goto err_alloc;
         }
 
         WARN_ON_ONCE(ctx->parent_ctx);
         mutex_lock(&ctx->mutex);
         if (ctx->task == TASK_TOMBSTONE) {
                 err = -ESRCH;
                 goto err_unlock;
         }
 
         pmu_ctx = find_get_pmu_context(pmu, ctx, event);
         if (IS_ERR(pmu_ctx)) {
                 err = PTR_ERR(pmu_ctx);
                 goto err_unlock;
         }
         event->pmu_ctx = pmu_ctx;
 
         if (!task) {
                 /*
                  * Check if the @cpu we're creating an event for is online.
                  *
                  * We use the perf_cpu_context::ctx::mutex to serialize against
                  * the hotplug notifiers. See perf_event_{init,exit}_cpu().
                  */
                 struct perf_cpu_context *cpuctx =
                         container_of(ctx, struct perf_cpu_context, ctx);
                 if (!cpuctx->online) {
                         err = -ENODEV;
                         goto err_pmu_ctx;
                 }
         }
 
         if (!exclusive_event_installable(event, ctx)) {
                 err = -EBUSY;
                 goto err_pmu_ctx;
         }
 
         perf_install_in_context(ctx, event, event->cpu);
         perf_unpin_context(ctx);
         mutex_unlock(&ctx->mutex);
 
         return event;
 
 err_pmu_ctx:
         put_pmu_ctx(pmu_ctx);
         event->pmu_ctx = NULL; /* _free_event() */
 err_unlock:
         mutex_unlock(&ctx->mutex);
         perf_unpin_context(ctx);
         put_ctx(ctx);
 err_alloc:
         free_event(event);
 err:
         return ERR_PTR(err);
 }
 EXPORT_SYMBOL_GPL(perf_event_create_kernel_counter);
 
 static void __perf_pmu_remove(struct perf_event_context *ctx,
                               int cpu, struct pmu *pmu,
                               struct perf_event_groups *groups,
                               struct list_head *events)
 {
         struct perf_event *event, *sibling;
 
         perf_event_groups_for_cpu_pmu(event, groups, cpu, pmu) {
                 perf_remove_from_context(event, 0);
                 put_pmu_ctx(event->pmu_ctx);
                 list_add(&event->migrate_entry, events);
 
                 for_each_sibling_event(sibling, event) {
                         perf_remove_from_context(sibling, 0);
                         put_pmu_ctx(sibling->pmu_ctx);
                         list_add(&sibling->migrate_entry, events);
                 }
         }
 }
 
 static void __perf_pmu_install_event(struct pmu *pmu,
                                      struct perf_event_context *ctx,
                                      int cpu, struct perf_event *event)
 {
         struct perf_event_pmu_context *epc;
         struct perf_event_context *old_ctx = event->ctx;
 
         get_ctx(ctx); /* normally find_get_context() */
 
         event->cpu = cpu;
         epc = find_get_pmu_context(pmu, ctx, event);
         event->pmu_ctx = epc;
 
         if (event->state >= PERF_EVENT_STATE_OFF)
                 event->state = PERF_EVENT_STATE_INACTIVE;
         perf_install_in_context(ctx, event, cpu);
 
         /*
          * Now that event->ctx is updated and visible, put the old ctx.
          */
         put_ctx(old_ctx);
 }
 
 static void __perf_pmu_install(struct perf_event_context *ctx,
                                int cpu, struct pmu *pmu, struct list_head *events)
 {
         struct perf_event *event, *tmp;
 
         /*
          * Re-instate events in 2 passes.
          *
          * Skip over group leaders and only install siblings on this first
          * pass, siblings will not get enabled without a leader, however a
          * leader will enable its siblings, even if those are still on the old
          * context.
          */
         list_for_each_entry_safe(event, tmp, events, migrate_entry) {
                 if (event->group_leader == event)
                         continue;
 
                 list_del(&event->migrate_entry);
                 __perf_pmu_install_event(pmu, ctx, cpu, event);
         }
 
         /*
          * Once all the siblings are setup properly, install the group leaders
          * to make it go.
          */
         list_for_each_entry_safe(event, tmp, events, migrate_entry) {
                 list_del(&event->migrate_entry);
                 __perf_pmu_install_event(pmu, ctx, cpu, event);
         }
 }
 
 void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
 {
         struct perf_event_context *src_ctx, *dst_ctx;
         LIST_HEAD(events);
 
         /*
          * Since per-cpu context is persistent, no need to grab an extra
          * reference.
          */
         src_ctx = &per_cpu_ptr(&perf_cpu_context, src_cpu)->ctx;
         dst_ctx = &per_cpu_ptr(&perf_cpu_context, dst_cpu)->ctx;
 
         /*
          * See perf_event_ctx_lock() for comments on the details
          * of swizzling perf_event::ctx.
          */
         mutex_lock_double(&src_ctx->mutex, &dst_ctx->mutex);
 
         __perf_pmu_remove(src_ctx, src_cpu, pmu, &src_ctx->pinned_groups, &events);
         __perf_pmu_remove(src_ctx, src_cpu, pmu, &src_ctx->flexible_groups, &events);
 
         if (!list_empty(&events)) {
                 /*
                  * Wait for the events to quiesce before re-instating them.
                  */
                 synchronize_rcu();
 
                 __perf_pmu_install(dst_ctx, dst_cpu, pmu, &events);
         }
 
         mutex_unlock(&dst_ctx->mutex);
         mutex_unlock(&src_ctx->mutex);
 }
 EXPORT_SYMBOL_GPL(perf_pmu_migrate_context);
 
 static void sync_child_event(struct perf_event *child_event)
 {
         struct perf_event *parent_event = child_event->parent;
         u64 child_val;
 
         if (child_event->attr.inherit_stat) {
                 struct task_struct *task = child_event->ctx->task;
 
                 if (task && task != TASK_TOMBSTONE)
                         perf_event_read_event(child_event, task);
         }
 
         child_val = perf_event_count(child_event);
 
         /*
          * Add back the child's count to the parent's count:
          */
         atomic64_add(child_val, &parent_event->child_count);
         atomic64_add(child_event->total_time_enabled,
                      &parent_event->child_total_time_enabled);
         atomic64_add(child_event->total_time_running,
                      &parent_event->child_total_time_running);
 }
 
 static void
 perf_event_exit_event(struct perf_event *event, struct perf_event_context *ctx)
 {
         struct perf_event *parent_event = event->parent;
         unsigned long detach_flags = 0;
 
         if (parent_event) {
                 /*
                  * Do not destroy the 'original' grouping; because of the
                  * context switch optimization the original events could've
                  * ended up in a random child task.
                  *
                  * If we were to destroy the original group, all group related
                  * operations would cease to function properly after this
                  * random child dies.
                  *
                  * Do destroy all inherited groups, we don't care about those
                  * and being thorough is better.
                  */
                 detach_flags = DETACH_GROUP | DETACH_CHILD;
                 mutex_lock(&parent_event->child_mutex);
         }
 
         perf_remove_from_context(event, detach_flags);
 
         raw_spin_lock_irq(&ctx->lock);
         if (event->state > PERF_EVENT_STATE_EXIT)
                 perf_event_set_state(event, PERF_EVENT_STATE_EXIT);
         raw_spin_unlock_irq(&ctx->lock);
 
         /*
          * Child events can be freed.
          */
         if (parent_event) {
                 mutex_unlock(&parent_event->child_mutex);
                 /*
                  * Kick perf_poll() for is_event_hup();
                  */
                 perf_event_wakeup(parent_event);
                 free_event(event);
                 put_event(parent_event);
                 return;
         }
 
         /*
          * Parent events are governed by their filedesc, retain them.
          */
         perf_event_wakeup(event);
 }
 
 static void perf_event_exit_task_context(struct task_struct *child)
 {
         struct perf_event_context *child_ctx, *clone_ctx = NULL;
         struct perf_event *child_event, *next;
 
         WARN_ON_ONCE(child != current);
 
         child_ctx = perf_pin_task_context(child);
         if (!child_ctx)
                 return;
 
         /*
          * In order to reduce the amount of tricky in ctx tear-down, we hold
          * ctx::mutex over the entire thing. This serializes against almost
          * everything that wants to access the ctx.
          *
          * The exception is sys_perf_event_open() /
          * perf_event_create_kernel_count() which does find_get_context()
          * without ctx::mutex (it cannot because of the move_group double mutex
          * lock thing). See the comments in perf_install_in_context().
          */
         mutex_lock(&child_ctx->mutex);
 
         /*
          * In a single ctx::lock section, de-schedule the events and detach the
          * context from the task such that we cannot ever get it scheduled back
          * in.
          */
         raw_spin_lock_irq(&child_ctx->lock);
         task_ctx_sched_out(child_ctx, EVENT_ALL);
 
         /*
          * Now that the context is inactive, destroy the task <-> ctx relation
          * and mark the context dead.
          */
         RCU_INIT_POINTER(child->perf_event_ctxp, NULL);
         put_ctx(child_ctx); /* cannot be last */
         WRITE_ONCE(child_ctx->task, TASK_TOMBSTONE);
         put_task_struct(current); /* cannot be last */
 
         clone_ctx = unclone_ctx(child_ctx);
         raw_spin_unlock_irq(&child_ctx->lock);
 
         if (clone_ctx)
                 put_ctx(clone_ctx);
 
         /*
          * Report the task dead after unscheduling the events so that we
          * won't get any samples after PERF_RECORD_EXIT. We can however still
          * get a few PERF_RECORD_READ events.
          */
         perf_event_task(child, child_ctx, 0);
 
         list_for_each_entry_safe(child_event, next, &child_ctx->event_list, event_entry)
                 perf_event_exit_event(child_event, child_ctx);
 
         mutex_unlock(&child_ctx->mutex);
 
         put_ctx(child_ctx);
 }
 
 /*
  * When a child task exits, feed back event values to parent events.
  *
  * Can be called with exec_update_lock held when called from
  * setup_new_exec().
  */
 void perf_event_exit_task(struct task_struct *child)
 {
         struct perf_event *event, *tmp;
 
         mutex_lock(&child->perf_event_mutex);
         list_for_each_entry_safe(event, tmp, &child->perf_event_list,
                                  owner_entry) {
                 list_del_init(&event->owner_entry);
 
                 /*
                  * Ensure the list deletion is visible before we clear
                  * the owner, closes a race against perf_release() where
                  * we need to serialize on the owner->perf_event_mutex.
                  */
                 smp_store_release(&event->owner, NULL);
         }
         mutex_unlock(&child->perf_event_mutex);
 
         perf_event_exit_task_context(child);
 
         /*
          * The perf_event_exit_task_context calls perf_event_task
          * with child's task_ctx, which generates EXIT events for
          * child contexts and sets child->perf_event_ctxp[] to NULL.
          * At this point we need to send EXIT events to cpu contexts.
          */
         perf_event_task(child, NULL, 0);
 }
 
 static void perf_free_event(struct perf_event *event,
                             struct perf_event_context *ctx)
 {
         struct perf_event *parent = event->parent;
 
         if (WARN_ON_ONCE(!parent))
                 return;
 
         mutex_lock(&parent->child_mutex);
         list_del_init(&event->child_list);
         mutex_unlock(&parent->child_mutex);
 
         put_event(parent);
 
         raw_spin_lock_irq(&ctx->lock);
         perf_group_detach(event);
         list_del_event(event, ctx);
         raw_spin_unlock_irq(&ctx->lock);
         free_event(event);
 }
 
 /*
  * Free a context as created by inheritance by perf_event_init_task() below,
  * used by fork() in case of fail.
  *
  * Even though the task has never lived, the context and events have been
  * exposed through the child_list, so we must take care tearing it all down.
  */
 void perf_event_free_task(struct task_struct *task)
 {
         struct perf_event_context *ctx;
         struct perf_event *event, *tmp;
 
         ctx = rcu_access_pointer(task->perf_event_ctxp);
         if (!ctx)
                 return;
 
         mutex_lock(&ctx->mutex);
         raw_spin_lock_irq(&ctx->lock);
         /*
          * Destroy the task <-> ctx relation and mark the context dead.
          *
          * This is important because even though the task hasn't been
          * exposed yet the context has been (through child_list).
          */
         RCU_INIT_POINTER(task->perf_event_ctxp, NULL);
         WRITE_ONCE(ctx->task, TASK_TOMBSTONE);
         put_task_struct(task); /* cannot be last */
         raw_spin_unlock_irq(&ctx->lock);
 
 
         list_for_each_entry_safe(event, tmp, &ctx->event_list, event_entry)
                 perf_free_event(event, ctx);
 
         mutex_unlock(&ctx->mutex);
 
         /*
          * perf_event_release_kernel() could've stolen some of our
          * child events and still have them on its free_list. In that
          * case we must wait for these events to have been freed (in
          * particular all their references to this task must've been
          * dropped).
          *
          * Without this copy_process() will unconditionally free this
          * task (irrespective of its reference count) and
          * _free_event()'s put_task_struct(event->hw.target) will be a
          * use-after-free.
          *
          * Wait for all events to drop their context reference.
          */
         wait_var_event(&ctx->refcount, refcount_read(&ctx->refcount) == 1);
         put_ctx(ctx); /* must be last */
 }
 
 void perf_event_delayed_put(struct task_struct *task)
 {
         WARN_ON_ONCE(task->perf_event_ctxp);
 }
 
 struct file *perf_event_get(unsigned int fd)
 {
         struct file *file = fget(fd);
         if (!file)
                 return ERR_PTR(-EBADF);
 
         if (file->f_op != &perf_fops) {
                 fput(file);
                 return ERR_PTR(-EBADF);
         }
 
         return file;
 }
 
 const struct perf_event *perf_get_event(struct file *file)
 {
         if (file->f_op != &perf_fops)
                 return ERR_PTR(-EINVAL);
 
         return file->private_data;
 }
 
 const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
 {
         if (!event)
                 return ERR_PTR(-EINVAL);
 
         return &event->attr;
 }
 
 int perf_allow_kernel(struct perf_event_attr *attr)
 {
         if (sysctl_perf_event_paranoid > 1 && !perfmon_capable())
                 return -EACCES;
 
         return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
 }
 EXPORT_SYMBOL_GPL(perf_allow_kernel);
 
 /*
  * Inherit an event from parent task to child task.
  *
  * Returns:
  *  - valid pointer on success
  *  - NULL for orphaned events
  *  - IS_ERR() on error
  */
 static struct perf_event *
 inherit_event(struct perf_event *parent_event,
               struct task_struct *parent,
               struct perf_event_context *parent_ctx,
               struct task_struct *child,
               struct perf_event *group_leader,
               struct perf_event_context *child_ctx)
 {
         enum perf_event_state parent_state = parent_event->state;
         struct perf_event_pmu_context *pmu_ctx;
         struct perf_event *child_event;
         unsigned long flags;
 
         /*
          * Instead of creating recursive hierarchies of events,
          * we link inherited events back to the original parent,
          * which has a filp for sure, which we use as the reference
          * count:
          */
         if (parent_event->parent)
                 parent_event = parent_event->parent;
 
         child_event = perf_event_alloc(&parent_event->attr,
                                            parent_event->cpu,
                                            child,
                                            group_leader, parent_event,
                                            NULL, NULL, -1);
         if (IS_ERR(child_event))
                 return child_event;
 
         pmu_ctx = find_get_pmu_context(child_event->pmu, child_ctx, child_event);
         if (IS_ERR(pmu_ctx)) {
                 free_event(child_event);
                 return ERR_CAST(pmu_ctx);
         }
         child_event->pmu_ctx = pmu_ctx;
 
         /*
          * is_orphaned_event() and list_add_tail(&parent_event->child_list)
          * must be under the same lock in order to serialize against
          * perf_event_release_kernel(), such that either we must observe
          * is_orphaned_event() or they will observe us on the child_list.
          */
         mutex_lock(&parent_event->child_mutex);
         if (is_orphaned_event(parent_event) ||
             !atomic_long_inc_not_zero(&parent_event->refcount)) {
                 mutex_unlock(&parent_event->child_mutex);
                 /* task_ctx_data is freed with child_ctx */
                 free_event(child_event);
                 return NULL;
         }
 
         get_ctx(child_ctx);
 
         /*
          * Make the child state follow the state of the parent event,
          * not its attr.disabled bit.  We hold the parent's mutex,
          * so we won't race with perf_event_{en, dis}able_family.
          */
         if (parent_state >= PERF_EVENT_STATE_INACTIVE)
                 child_event->state = PERF_EVENT_STATE_INACTIVE;
         else
                 child_event->state = PERF_EVENT_STATE_OFF;
 
         if (parent_event->attr.freq) {
                 u64 sample_period = parent_event->hw.sample_period;
                 struct hw_perf_event *hwc = &child_event->hw;
 
                 hwc->sample_period = sample_period;
                 hwc->last_period   = sample_period;
 
                 local64_set(&hwc->period_left, sample_period);
         }
 
         child_event->ctx = child_ctx;
         child_event->overflow_handler = parent_event->overflow_handler;
         child_event->overflow_handler_context
                 = parent_event->overflow_handler_context;
 
         /*
          * Precalculate sample_data sizes
          */
         perf_event__header_size(child_event);
         perf_event__id_header_size(child_event);
 
         /*
          * Link it up in the child's context:
          */
         raw_spin_lock_irqsave(&child_ctx->lock, flags);
         add_event_to_ctx(child_event, child_ctx);
         child_event->attach_state |= PERF_ATTACH_CHILD;
         raw_spin_unlock_irqrestore(&child_ctx->lock, flags);
 
         /*
          * Link this into the parent event's child list
          */
         list_add_tail(&child_event->child_list, &parent_event->child_list);
         mutex_unlock(&parent_event->child_mutex);
 
         return child_event;
 }
 
 /*
  * Inherits an event group.
  *
  * This will quietly suppress orphaned events; !inherit_event() is not an error.
  * This matches with perf_event_release_kernel() removing all child events.
  *
  * Returns:
  *  - 0 on success
  *  - <0 on error
  */
 static int inherit_group(struct perf_event *parent_event,
               struct task_struct *parent,
               struct perf_event_context *parent_ctx,
               struct task_struct *child,
               struct perf_event_context *child_ctx)
 {
         struct perf_event *leader;
         struct perf_event *sub;
         struct perf_event *child_ctr;
 
         leader = inherit_event(parent_event, parent, parent_ctx,
                                  child, NULL, child_ctx);
         if (IS_ERR(leader))
                 return PTR_ERR(leader);
         /*
          * @leader can be NULL here because of is_orphaned_event(). In this
          * case inherit_event() will create individual events, similar to what
          * perf_group_detach() would do anyway.
          */
         for_each_sibling_event(sub, parent_event) {
                 child_ctr = inherit_event(sub, parent, parent_ctx,
                                             child, leader, child_ctx);
                 if (IS_ERR(child_ctr))
                         return PTR_ERR(child_ctr);
 
                 if (sub->aux_event == parent_event && child_ctr &&
                     !perf_get_aux_event(child_ctr, leader))
                         return -EINVAL;
         }
         if (leader)
                 leader->group_generation = parent_event->group_generation;
         return 0;
 }
 
 /*
  * Creates the child task context and tries to inherit the event-group.
  *
  * Clears @inherited_all on !attr.inherited or error. Note that we'll leave
  * inherited_all set when we 'fail' to inherit an orphaned event; this is
  * consistent with perf_event_release_kernel() removing all child events.
  *
  * Returns:
  *  - 0 on success
  *  - <0 on error
  */
 static int
 inherit_task_group(struct perf_event *event, struct task_struct *parent,
                    struct perf_event_context *parent_ctx,
                    struct task_struct *child,
                    u64 clone_flags, int *inherited_all)
 {
         struct perf_event_context *child_ctx;
         int ret;
 
         if (!event->attr.inherit ||
             (event->attr.inherit_thread && !(clone_flags & CLONE_THREAD)) ||
             /* Do not inherit if sigtrap and signal handlers were cleared. */
             (event->attr.sigtrap && (clone_flags & CLONE_CLEAR_SIGHAND))) {
                 *inherited_all = 0;
                 return 0;
         }
 
         child_ctx = child->perf_event_ctxp;
         if (!child_ctx) {
                 /*
                  * This is executed from the parent task context, so
                  * inherit events that have been marked for cloning.
                  * First allocate and initialize a context for the
                  * child.
                  */
                 child_ctx = alloc_perf_context(child);
                 if (!child_ctx)
                         return -ENOMEM;
 
                 child->perf_event_ctxp = child_ctx;
         }
 
         ret = inherit_group(event, parent, parent_ctx, child, child_ctx);
         if (ret)
                 *inherited_all = 0;
 
         return ret;
 }
 
 /*
  * Initialize the perf_event context in task_struct
  */
 static int perf_event_init_context(struct task_struct *child, u64 clone_flags)
 {
         struct perf_event_context *child_ctx, *parent_ctx;
         struct perf_event_context *cloned_ctx;
         struct perf_event *event;
         struct task_struct *parent = current;
         int inherited_all = 1;
         unsigned long flags;
         int ret = 0;
 
         if (likely(!parent->perf_event_ctxp))
                 return 0;
 
         /*
          * If the parent's context is a clone, pin it so it won't get
          * swapped under us.
          */
         parent_ctx = perf_pin_task_context(parent);
         if (!parent_ctx)
                 return 0;
 
         /*
          * No need to check if parent_ctx != NULL here; since we saw
          * it non-NULL earlier, the only reason for it to become NULL
          * is if we exit, and since we're currently in the middle of
          * a fork we can't be exiting at the same time.
          */
 
         /*
          * Lock the parent list. No need to lock the child - not PID
          * hashed yet and not running, so nobody can access it.
          */
         mutex_lock(&parent_ctx->mutex);
 
         /*
          * We dont have to disable NMIs - we are only looking at
          * the list, not manipulating it:
          */
         perf_event_groups_for_each(event, &parent_ctx->pinned_groups) {
                 ret = inherit_task_group(event, parent, parent_ctx,
                                          child, clone_flags, &inherited_all);
                 if (ret)
                         goto out_unlock;
         }
 
         /*
          * We can't hold ctx->lock when iterating the ->flexible_group list due
          * to allocations, but we need to prevent rotation because
          * rotate_ctx() will change the list from interrupt context.
          */
         raw_spin_lock_irqsave(&parent_ctx->lock, flags);
         parent_ctx->rotate_disable = 1;
         raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
 
         perf_event_groups_for_each(event, &parent_ctx->flexible_groups) {
                 ret = inherit_task_group(event, parent, parent_ctx,
                                          child, clone_flags, &inherited_all);
                 if (ret)
                         goto out_unlock;
         }
 
         raw_spin_lock_irqsave(&parent_ctx->lock, flags);
         parent_ctx->rotate_disable = 0;
 
         child_ctx = child->perf_event_ctxp;
 
         if (child_ctx && inherited_all) {
                 /*
                  * Mark the child context as a clone of the parent
                  * context, or of whatever the parent is a clone of.
                  *
                  * Note that if the parent is a clone, the holding of
                  * parent_ctx->lock avoids it from being uncloned.
                  */
                 cloned_ctx = parent_ctx->parent_ctx;
                 if (cloned_ctx) {
                         child_ctx->parent_ctx = cloned_ctx;
                         child_ctx->parent_gen = parent_ctx->parent_gen;
                 } else {
                         child_ctx->parent_ctx = parent_ctx;
                         child_ctx->parent_gen = parent_ctx->generation;
                 }
                 get_ctx(child_ctx->parent_ctx);
         }
 
         raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
 out_unlock:
         mutex_unlock(&parent_ctx->mutex);
 
         perf_unpin_context(parent_ctx);
         put_ctx(parent_ctx);
 
         return ret;
 }
 
 /*
  * Initialize the perf_event context in task_struct
  */
 int perf_event_init_task(struct task_struct *child, u64 clone_flags)
 {
         int ret;
 
         memset(child->perf_recursion, 0, sizeof(child->perf_recursion));
         child->perf_event_ctxp = NULL;
         mutex_init(&child->perf_event_mutex);
         INIT_LIST_HEAD(&child->perf_event_list);
 
         ret = perf_event_init_context(child, clone_flags);
         if (ret) {
                 perf_event_free_task(child);
                 return ret;
         }
 
         return 0;
 }
 
 static void __init perf_event_init_all_cpus(void)
 {
         struct swevent_htable *swhash;
         struct perf_cpu_context *cpuctx;
         int cpu;
 
         zalloc_cpumask_var(&perf_online_mask, GFP_KERNEL);
 
         for_each_possible_cpu(cpu) {
                 swhash = &per_cpu(swevent_htable, cpu);
                 mutex_init(&swhash->hlist_mutex);
 
                 INIT_LIST_HEAD(&per_cpu(pmu_sb_events.list, cpu));
                 raw_spin_lock_init(&per_cpu(pmu_sb_events.lock, cpu));
 
                 INIT_LIST_HEAD(&per_cpu(sched_cb_list, cpu));
 
                 cpuctx = per_cpu_ptr(&perf_cpu_context, cpu);
                 __perf_event_init_context(&cpuctx->ctx);
                 lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
                 lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock);
                 cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask);
                 cpuctx->heap_size = ARRAY_SIZE(cpuctx->heap_default);
                 cpuctx->heap = cpuctx->heap_default;
         }
 }
 
 static void perf_swevent_init_cpu(unsigned int cpu)
 {
         struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
 
         mutex_lock(&swhash->hlist_mutex);
         if (swhash->hlist_refcount > 0 && !swevent_hlist_deref(swhash)) {
                 struct swevent_hlist *hlist;
 
                 hlist = kzalloc_node(sizeof(*hlist), GFP_KERNEL, cpu_to_node(cpu));
                 WARN_ON(!hlist);
                 rcu_assign_pointer(swhash->swevent_hlist, hlist);
         }
         mutex_unlock(&swhash->hlist_mutex);
 }
 
 #if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC_CORE
 static void __perf_event_exit_context(void *__info)
 {
         struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context);
         struct perf_event_context *ctx = __info;
         struct perf_event *event;
 
         raw_spin_lock(&ctx->lock);
         ctx_sched_out(ctx, EVENT_TIME);
         list_for_each_entry(event, &ctx->event_list, event_entry)
                 __perf_remove_from_context(event, cpuctx, ctx, (void *)DETACH_GROUP);
         raw_spin_unlock(&ctx->lock);
 }
 
 static void perf_event_exit_cpu_context(int cpu)
 {
         struct perf_cpu_context *cpuctx;
         struct perf_event_context *ctx;
 
         // XXX simplify cpuctx->online
         mutex_lock(&pmus_lock);
         cpuctx = per_cpu_ptr(&perf_cpu_context, cpu);
         ctx = &cpuctx->ctx;
 
         mutex_lock(&ctx->mutex);
         smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
         cpuctx->online = 0;
         mutex_unlock(&ctx->mutex);
         cpumask_clear_cpu(cpu, perf_online_mask);
         mutex_unlock(&pmus_lock);
 }
 #else
 
 static void perf_event_exit_cpu_context(int cpu) { }
 
 #endif
 
 int perf_event_init_cpu(unsigned int cpu)
 {
         struct perf_cpu_context *cpuctx;
         struct perf_event_context *ctx;
 
         perf_swevent_init_cpu(cpu);
 
         mutex_lock(&pmus_lock);
         cpumask_set_cpu(cpu, perf_online_mask);
         cpuctx = per_cpu_ptr(&perf_cpu_context, cpu);
         ctx = &cpuctx->ctx;
 
         mutex_lock(&ctx->mutex);
         cpuctx->online = 1;
         mutex_unlock(&ctx->mutex);
         mutex_unlock(&pmus_lock);
 
         return 0;
 }
 
 int perf_event_exit_cpu(unsigned int cpu)
 {
         perf_event_exit_cpu_context(cpu);
         return 0;
 }
 
 static int
 perf_reboot(struct notifier_block *notifier, unsigned long val, void *v)
 {
         int cpu;
 
         for_each_online_cpu(cpu)
                 perf_event_exit_cpu(cpu);
 
         return NOTIFY_OK;
 }
 
 /*
  * Run the perf reboot notifier at the very last possible moment so that
  * the generic watchdog code runs as long as possible.
  */
 static struct notifier_block perf_reboot_notifier = {
         .notifier_call = perf_reboot,
         .priority = INT_MIN,
 };
 
 void __init perf_event_init(void)
 {
         int ret;
 
         idr_init(&pmu_idr);
 
         perf_event_init_all_cpus();
         init_srcu_struct(&pmus_srcu);
         perf_pmu_register(&perf_swevent, "software", PERF_TYPE_SOFTWARE);
         perf_pmu_register(&perf_cpu_clock, "cpu_clock", -1);
         perf_pmu_register(&perf_task_clock, "task_clock", -1);
         perf_tp_register();
         perf_event_init_cpu(smp_processor_id());
         register_reboot_notifier(&perf_reboot_notifier);
 
         ret = init_hw_breakpoint();
         WARN(ret, "hw_breakpoint initialization failed with: %d", ret);
 
         perf_event_cache = KMEM_CACHE(perf_event, SLAB_PANIC);
 
         /*
          * Build time assertion that we keep the data_head at the intended
          * location.  IOW, validation we got the __reserved[] size right.
          */
         BUILD_BUG_ON((offsetof(struct perf_event_mmap_page, data_head))
                      != 1024);
 }
 
 ssize_t perf_event_sysfs_show(struct device *dev, struct device_attribute *attr,
                               char *page)
 {
         struct perf_pmu_events_attr *pmu_attr =
                 container_of(attr, struct perf_pmu_events_attr, attr);
 
         if (pmu_attr->event_str)
                 return sprintf(page, "%s\n", pmu_attr->event_str);
 
         return 0;
 }
 EXPORT_SYMBOL_GPL(perf_event_sysfs_show);
 
 static int __init perf_event_sysfs_init(void)
 {
         struct pmu *pmu;
         int ret;
 
         mutex_lock(&pmus_lock);
 
         ret = bus_register(&pmu_bus);
         if (ret)
                 goto unlock;
 
         list_for_each_entry(pmu, &pmus, entry) {
                 if (pmu->dev)
                         continue;
 
                 ret = pmu_dev_alloc(pmu);
                 WARN(ret, "Failed to register pmu: %s, reason %d\n", pmu->name, ret);
         }
         pmu_bus_running = 1;
         ret = 0;
 
 unlock:
         mutex_unlock(&pmus_lock);
 
         return ret;
 }
 device_initcall(perf_event_sysfs_init);
 
 #ifdef CONFIG_CGROUP_PERF
 static struct cgroup_subsys_state *
 perf_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 {
         struct perf_cgroup *jc;
 
         jc = kzalloc(sizeof(*jc), GFP_KERNEL);
         if (!jc)
                 return ERR_PTR(-ENOMEM);
 
         jc->info = alloc_percpu(struct perf_cgroup_info);
         if (!jc->info) {
                 kfree(jc);
                 return ERR_PTR(-ENOMEM);
         }
 
         return &jc->css;
 }
 
 static void perf_cgroup_css_free(struct cgroup_subsys_state *css)
 {
         struct perf_cgroup *jc = container_of(css, struct perf_cgroup, css);
 
         free_percpu(jc->info);
         kfree(jc);
 }
 
 static int perf_cgroup_css_online(struct cgroup_subsys_state *css)
 {
         perf_event_cgroup(css->cgroup);
         return 0;
 }
 
 static int __perf_cgroup_move(void *info)
 {
         struct task_struct *task = info;
 
         preempt_disable();
         perf_cgroup_switch(task);
         preempt_enable();
 
         return 0;
 }
 
 static void perf_cgroup_attach(struct cgroup_taskset *tset)
 {
         struct task_struct *task;
         struct cgroup_subsys_state *css;
 
         cgroup_taskset_for_each(task, css, tset)
                 task_function_call(task, __perf_cgroup_move, task);
 }
 
 struct cgroup_subsys perf_event_cgrp_subsys = {
         .css_alloc      = perf_cgroup_css_alloc,
         .css_free       = perf_cgroup_css_free,
         .css_online     = perf_cgroup_css_online,
         .attach         = perf_cgroup_attach,
         /*
          * Implicitly enable on dfl hierarchy so that perf events can
          * always be filtered by cgroup2 path as long as perf_event
          * controller is not mounted on a legacy hierarchy.
          */
         .implicit_on_dfl = true,
         .threaded       = true,
 };
 #endif /* CONFIG_CGROUP_PERF */
 
 DEFINE_STATIC_CALL_RET0(perf_snapshot_branch_stack, perf_snapshot_branch_stack_t);