TOMOYO Linux Cross Reference
Linux/kernel/bpf/btf.c

   // SPDX-License-Identifier: GPL-2.0
   /* Copyright (c) 2018 Facebook */
   
   #include <uapi/linux/btf.h>
   #include <uapi/linux/bpf.h>
   #include <uapi/linux/bpf_perf_event.h>
   #include <uapi/linux/types.h>
   #include <linux/seq_file.h>
   #include <linux/compiler.h>
  #include <linux/ctype.h>
  #include <linux/errno.h>
  #include <linux/slab.h>
  #include <linux/anon_inodes.h>
  #include <linux/file.h>
  #include <linux/uaccess.h>
  #include <linux/kernel.h>
  #include <linux/idr.h>
  #include <linux/sort.h>
  #include <linux/bpf_verifier.h>
  #include <linux/btf.h>
  #include <linux/btf_ids.h>
  #include <linux/bpf.h>
  #include <linux/bpf_lsm.h>
  #include <linux/skmsg.h>
  #include <linux/perf_event.h>
  #include <linux/bsearch.h>
  #include <linux/kobject.h>
  #include <linux/sysfs.h>
  
  #include <net/netfilter/nf_bpf_link.h>
  
  #include <net/sock.h>
  #include <net/xdp.h>
  #include "../tools/lib/bpf/relo_core.h"
  
  /* BTF (BPF Type Format) is the meta data format which describes
   * the data types of BPF program/map.  Hence, it basically focus
   * on the C programming language which the modern BPF is primary
   * using.
   *
   * ELF Section:
   * ~~~~~~~~~~~
   * The BTF data is stored under the ".BTF" ELF section
   *
   * struct btf_type:
   * ~~~~~~~~~~~~~~~
   * Each 'struct btf_type' object describes a C data type.
   * Depending on the type it is describing, a 'struct btf_type'
   * object may be followed by more data.  F.e.
   * To describe an array, 'struct btf_type' is followed by
   * 'struct btf_array'.
   *
   * 'struct btf_type' and any extra data following it are
   * 4 bytes aligned.
   *
   * Type section:
   * ~~~~~~~~~~~~~
   * The BTF type section contains a list of 'struct btf_type' objects.
   * Each one describes a C type.  Recall from the above section
   * that a 'struct btf_type' object could be immediately followed by extra
   * data in order to describe some particular C types.
   *
   * type_id:
   * ~~~~~~~
   * Each btf_type object is identified by a type_id.  The type_id
   * is implicitly implied by the location of the btf_type object in
   * the BTF type section.  The first one has type_id 1.  The second
   * one has type_id 2...etc.  Hence, an earlier btf_type has
   * a smaller type_id.
   *
   * A btf_type object may refer to another btf_type object by using
   * type_id (i.e. the "type" in the "struct btf_type").
   *
   * NOTE that we cannot assume any reference-order.
   * A btf_type object can refer to an earlier btf_type object
   * but it can also refer to a later btf_type object.
   *
   * For example, to describe "const void *".  A btf_type
   * object describing "const" may refer to another btf_type
   * object describing "void *".  This type-reference is done
   * by specifying type_id:
   *
   * [1] CONST (anon) type_id=2
   * [2] PTR (anon) type_id=0
   *
   * The above is the btf_verifier debug log:
   *   - Each line started with "[?]" is a btf_type object
   *   - [?] is the type_id of the btf_type object.
   *   - CONST/PTR is the BTF_KIND_XXX
   *   - "(anon)" is the name of the type.  It just
   *     happens that CONST and PTR has no name.
   *   - type_id=XXX is the 'u32 type' in btf_type
   *
   * NOTE: "void" has type_id 0
   *
   * String section:
   * ~~~~~~~~~~~~~~
   * The BTF string section contains the names used by the type section.
   * Each string is referred by an "offset" from the beginning of the
  * string section.
  *
  * Each string is '\0' terminated.
  *
  * The first character in the string section must be '\0'
  * which is used to mean 'anonymous'. Some btf_type may not
  * have a name.
  */
 
 /* BTF verification:
  *
  * To verify BTF data, two passes are needed.
  *
  * Pass #1
  * ~~~~~~~
  * The first pass is to collect all btf_type objects to
  * an array: "btf->types".
  *
  * Depending on the C type that a btf_type is describing,
  * a btf_type may be followed by extra data.  We don't know
  * how many btf_type is there, and more importantly we don't
  * know where each btf_type is located in the type section.
  *
  * Without knowing the location of each type_id, most verifications
  * cannot be done.  e.g. an earlier btf_type may refer to a later
  * btf_type (recall the "const void *" above), so we cannot
  * check this type-reference in the first pass.
  *
  * In the first pass, it still does some verifications (e.g.
  * checking the name is a valid offset to the string section).
  *
  * Pass #2
  * ~~~~~~~
  * The main focus is to resolve a btf_type that is referring
  * to another type.
  *
  * We have to ensure the referring type:
  * 1) does exist in the BTF (i.e. in btf->types[])
  * 2) does not cause a loop:
  *      struct A {
  *              struct B b;
  *      };
  *
  *      struct B {
  *              struct A a;
  *      };
  *
  * btf_type_needs_resolve() decides if a btf_type needs
  * to be resolved.
  *
  * The needs_resolve type implements the "resolve()" ops which
  * essentially does a DFS and detects backedge.
  *
  * During resolve (or DFS), different C types have different
  * "RESOLVED" conditions.
  *
  * When resolving a BTF_KIND_STRUCT, we need to resolve all its
  * members because a member is always referring to another
  * type.  A struct's member can be treated as "RESOLVED" if
  * it is referring to a BTF_KIND_PTR.  Otherwise, the
  * following valid C struct would be rejected:
  *
  *      struct A {
  *              int m;
  *              struct A *a;
  *      };
  *
  * When resolving a BTF_KIND_PTR, it needs to keep resolving if
  * it is referring to another BTF_KIND_PTR.  Otherwise, we cannot
  * detect a pointer loop, e.g.:
  * BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
  *                        ^                                         |
  *                        +-----------------------------------------+
  *
  */
 
 #define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
 #define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
 #define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
 #define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
 #define BITS_ROUNDUP_BYTES(bits) \
         (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
 
 #define BTF_INFO_MASK 0x9f00ffff
 #define BTF_INT_MASK 0x0fffffff
 #define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
 #define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)
 
 /* 16MB for 64k structs and each has 16 members and
  * a few MB spaces for the string section.
  * The hard limit is S32_MAX.
  */
 #define BTF_MAX_SIZE (16 * 1024 * 1024)
 
 #define for_each_member_from(i, from, struct_type, member)              \
         for (i = from, member = btf_type_member(struct_type) + from;    \
              i < btf_type_vlen(struct_type);                            \
              i++, member++)
 
 #define for_each_vsi_from(i, from, struct_type, member)                         \
         for (i = from, member = btf_type_var_secinfo(struct_type) + from;       \
              i < btf_type_vlen(struct_type);                                    \
              i++, member++)
 
 DEFINE_IDR(btf_idr);
 DEFINE_SPINLOCK(btf_idr_lock);
 
 enum btf_kfunc_hook {
         BTF_KFUNC_HOOK_COMMON,
         BTF_KFUNC_HOOK_XDP,
         BTF_KFUNC_HOOK_TC,
         BTF_KFUNC_HOOK_STRUCT_OPS,
         BTF_KFUNC_HOOK_TRACING,
         BTF_KFUNC_HOOK_SYSCALL,
         BTF_KFUNC_HOOK_FMODRET,
         BTF_KFUNC_HOOK_CGROUP_SKB,
         BTF_KFUNC_HOOK_SCHED_ACT,
         BTF_KFUNC_HOOK_SK_SKB,
         BTF_KFUNC_HOOK_SOCKET_FILTER,
         BTF_KFUNC_HOOK_LWT,
         BTF_KFUNC_HOOK_NETFILTER,
         BTF_KFUNC_HOOK_KPROBE,
         BTF_KFUNC_HOOK_MAX,
 };
 
 enum {
         BTF_KFUNC_SET_MAX_CNT = 256,
         BTF_DTOR_KFUNC_MAX_CNT = 256,
         BTF_KFUNC_FILTER_MAX_CNT = 16,
 };
 
 struct btf_kfunc_hook_filter {
         btf_kfunc_filter_t filters[BTF_KFUNC_FILTER_MAX_CNT];
         u32 nr_filters;
 };
 
 struct btf_kfunc_set_tab {
         struct btf_id_set8 *sets[BTF_KFUNC_HOOK_MAX];
         struct btf_kfunc_hook_filter hook_filters[BTF_KFUNC_HOOK_MAX];
 };
 
 struct btf_id_dtor_kfunc_tab {
         u32 cnt;
         struct btf_id_dtor_kfunc dtors[];
 };
 
 struct btf_struct_ops_tab {
         u32 cnt;
         u32 capacity;
         struct bpf_struct_ops_desc ops[];
 };
 
 struct btf {
         void *data;
         struct btf_type **types;
         u32 *resolved_ids;
         u32 *resolved_sizes;
         const char *strings;
         void *nohdr_data;
         struct btf_header hdr;
         u32 nr_types; /* includes VOID for base BTF */
         u32 types_size;
         u32 data_size;
         refcount_t refcnt;
         u32 id;
         struct rcu_head rcu;
         struct btf_kfunc_set_tab *kfunc_set_tab;
         struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab;
         struct btf_struct_metas *struct_meta_tab;
         struct btf_struct_ops_tab *struct_ops_tab;
 
         /* split BTF support */
         struct btf *base_btf;
         u32 start_id; /* first type ID in this BTF (0 for base BTF) */
         u32 start_str_off; /* first string offset (0 for base BTF) */
         char name[MODULE_NAME_LEN];
         bool kernel_btf;
         __u32 *base_id_map; /* map from distilled base BTF -> vmlinux BTF ids */
 };
 
 enum verifier_phase {
         CHECK_META,
         CHECK_TYPE,
 };
 
 struct resolve_vertex {
         const struct btf_type *t;
         u32 type_id;
         u16 next_member;
 };
 
 enum visit_state {
         NOT_VISITED,
         VISITED,
         RESOLVED,
 };
 
 enum resolve_mode {
         RESOLVE_TBD,    /* To Be Determined */
         RESOLVE_PTR,    /* Resolving for Pointer */
         RESOLVE_STRUCT_OR_ARRAY,        /* Resolving for struct/union
                                          * or array
                                          */
 };
 
 #define MAX_RESOLVE_DEPTH 32
 
 struct btf_sec_info {
         u32 off;
         u32 len;
 };
 
 struct btf_verifier_env {
         struct btf *btf;
         u8 *visit_states;
         struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
         struct bpf_verifier_log log;
         u32 log_type_id;
         u32 top_stack;
         enum verifier_phase phase;
         enum resolve_mode resolve_mode;
 };
 
 static const char * const btf_kind_str[NR_BTF_KINDS] = {
         [BTF_KIND_UNKN]         = "UNKNOWN",
         [BTF_KIND_INT]          = "INT",
         [BTF_KIND_PTR]          = "PTR",
         [BTF_KIND_ARRAY]        = "ARRAY",
         [BTF_KIND_STRUCT]       = "STRUCT",
         [BTF_KIND_UNION]        = "UNION",
         [BTF_KIND_ENUM]         = "ENUM",
         [BTF_KIND_FWD]          = "FWD",
         [BTF_KIND_TYPEDEF]      = "TYPEDEF",
         [BTF_KIND_VOLATILE]     = "VOLATILE",
         [BTF_KIND_CONST]        = "CONST",
         [BTF_KIND_RESTRICT]     = "RESTRICT",
         [BTF_KIND_FUNC]         = "FUNC",
         [BTF_KIND_FUNC_PROTO]   = "FUNC_PROTO",
         [BTF_KIND_VAR]          = "VAR",
         [BTF_KIND_DATASEC]      = "DATASEC",
         [BTF_KIND_FLOAT]        = "FLOAT",
         [BTF_KIND_DECL_TAG]     = "DECL_TAG",
         [BTF_KIND_TYPE_TAG]     = "TYPE_TAG",
         [BTF_KIND_ENUM64]       = "ENUM64",
 };
 
 const char *btf_type_str(const struct btf_type *t)
 {
         return btf_kind_str[BTF_INFO_KIND(t->info)];
 }
 
 /* Chunk size we use in safe copy of data to be shown. */
 #define BTF_SHOW_OBJ_SAFE_SIZE          32
 
 /*
  * This is the maximum size of a base type value (equivalent to a
  * 128-bit int); if we are at the end of our safe buffer and have
  * less than 16 bytes space we can't be assured of being able
  * to copy the next type safely, so in such cases we will initiate
  * a new copy.
  */
 #define BTF_SHOW_OBJ_BASE_TYPE_SIZE     16
 
 /* Type name size */
 #define BTF_SHOW_NAME_SIZE              80
 
 /*
  * The suffix of a type that indicates it cannot alias another type when
  * comparing BTF IDs for kfunc invocations.
  */
 #define NOCAST_ALIAS_SUFFIX             "___init"
 
 /*
  * Common data to all BTF show operations. Private show functions can add
  * their own data to a structure containing a struct btf_show and consult it
  * in the show callback.  See btf_type_show() below.
  *
  * One challenge with showing nested data is we want to skip 0-valued
  * data, but in order to figure out whether a nested object is all zeros
  * we need to walk through it.  As a result, we need to make two passes
  * when handling structs, unions and arrays; the first path simply looks
  * for nonzero data, while the second actually does the display.  The first
  * pass is signalled by show->state.depth_check being set, and if we
  * encounter a non-zero value we set show->state.depth_to_show to
  * the depth at which we encountered it.  When we have completed the
  * first pass, we will know if anything needs to be displayed if
  * depth_to_show > depth.  See btf_[struct,array]_show() for the
  * implementation of this.
  *
  * Another problem is we want to ensure the data for display is safe to
  * access.  To support this, the anonymous "struct {} obj" tracks the data
  * object and our safe copy of it.  We copy portions of the data needed
  * to the object "copy" buffer, but because its size is limited to
  * BTF_SHOW_OBJ_COPY_LEN bytes, multiple copies may be required as we
  * traverse larger objects for display.
  *
  * The various data type show functions all start with a call to
  * btf_show_start_type() which returns a pointer to the safe copy
  * of the data needed (or if BTF_SHOW_UNSAFE is specified, to the
  * raw data itself).  btf_show_obj_safe() is responsible for
  * using copy_from_kernel_nofault() to update the safe data if necessary
  * as we traverse the object's data.  skbuff-like semantics are
  * used:
  *
  * - obj.head points to the start of the toplevel object for display
  * - obj.size is the size of the toplevel object
  * - obj.data points to the current point in the original data at
  *   which our safe data starts.  obj.data will advance as we copy
  *   portions of the data.
  *
  * In most cases a single copy will suffice, but larger data structures
  * such as "struct task_struct" will require many copies.  The logic in
  * btf_show_obj_safe() handles the logic that determines if a new
  * copy_from_kernel_nofault() is needed.
  */
 struct btf_show {
         u64 flags;
         void *target;   /* target of show operation (seq file, buffer) */
         __printf(2, 0) void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
         const struct btf *btf;
         /* below are used during iteration */
         struct {
                 u8 depth;
                 u8 depth_to_show;
                 u8 depth_check;
                 u8 array_member:1,
                    array_terminated:1;
                 u16 array_encoding;
                 u32 type_id;
                 int status;                     /* non-zero for error */
                 const struct btf_type *type;
                 const struct btf_member *member;
                 char name[BTF_SHOW_NAME_SIZE];  /* space for member name/type */
         } state;
         struct {
                 u32 size;
                 void *head;
                 void *data;
                 u8 safe[BTF_SHOW_OBJ_SAFE_SIZE];
         } obj;
 };
 
 struct btf_kind_operations {
         s32 (*check_meta)(struct btf_verifier_env *env,
                           const struct btf_type *t,
                           u32 meta_left);
         int (*resolve)(struct btf_verifier_env *env,
                        const struct resolve_vertex *v);
         int (*check_member)(struct btf_verifier_env *env,
                             const struct btf_type *struct_type,
                             const struct btf_member *member,
                             const struct btf_type *member_type);
         int (*check_kflag_member)(struct btf_verifier_env *env,
                                   const struct btf_type *struct_type,
                                   const struct btf_member *member,
                                   const struct btf_type *member_type);
         void (*log_details)(struct btf_verifier_env *env,
                             const struct btf_type *t);
         void (*show)(const struct btf *btf, const struct btf_type *t,
                          u32 type_id, void *data, u8 bits_offsets,
                          struct btf_show *show);
 };
 
 static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
 static struct btf_type btf_void;
 
 static int btf_resolve(struct btf_verifier_env *env,
                        const struct btf_type *t, u32 type_id);
 
 static int btf_func_check(struct btf_verifier_env *env,
                           const struct btf_type *t);
 
 static bool btf_type_is_modifier(const struct btf_type *t)
 {
         /* Some of them is not strictly a C modifier
          * but they are grouped into the same bucket
          * for BTF concern:
          *   A type (t) that refers to another
          *   type through t->type AND its size cannot
          *   be determined without following the t->type.
          *
          * ptr does not fall into this bucket
          * because its size is always sizeof(void *).
          */
         switch (BTF_INFO_KIND(t->info)) {
         case BTF_KIND_TYPEDEF:
         case BTF_KIND_VOLATILE:
         case BTF_KIND_CONST:
         case BTF_KIND_RESTRICT:
         case BTF_KIND_TYPE_TAG:
                 return true;
         }
 
         return false;
 }
 
 bool btf_type_is_void(const struct btf_type *t)
 {
         return t == &btf_void;
 }
 
 static bool btf_type_is_fwd(const struct btf_type *t)
 {
         return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
 }
 
 static bool btf_type_is_datasec(const struct btf_type *t)
 {
         return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
 }
 
 static bool btf_type_is_decl_tag(const struct btf_type *t)
 {
         return BTF_INFO_KIND(t->info) == BTF_KIND_DECL_TAG;
 }
 
 static bool btf_type_nosize(const struct btf_type *t)
 {
         return btf_type_is_void(t) || btf_type_is_fwd(t) ||
                btf_type_is_func(t) || btf_type_is_func_proto(t) ||
                btf_type_is_decl_tag(t);
 }
 
 static bool btf_type_nosize_or_null(const struct btf_type *t)
 {
         return !t || btf_type_nosize(t);
 }
 
 static bool btf_type_is_decl_tag_target(const struct btf_type *t)
 {
         return btf_type_is_func(t) || btf_type_is_struct(t) ||
                btf_type_is_var(t) || btf_type_is_typedef(t);
 }
 
 bool btf_is_vmlinux(const struct btf *btf)
 {
         return btf->kernel_btf && !btf->base_btf;
 }
 
 u32 btf_nr_types(const struct btf *btf)
 {
         u32 total = 0;
 
         while (btf) {
                 total += btf->nr_types;
                 btf = btf->base_btf;
         }
 
         return total;
 }
 
 s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
 {
         const struct btf_type *t;
         const char *tname;
         u32 i, total;
 
         total = btf_nr_types(btf);
         for (i = 1; i < total; i++) {
                 t = btf_type_by_id(btf, i);
                 if (BTF_INFO_KIND(t->info) != kind)
                         continue;
 
                 tname = btf_name_by_offset(btf, t->name_off);
                 if (!strcmp(tname, name))
                         return i;
         }
 
         return -ENOENT;
 }
 
 s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
 {
         struct btf *btf;
         s32 ret;
         int id;
 
         btf = bpf_get_btf_vmlinux();
         if (IS_ERR(btf))
                 return PTR_ERR(btf);
         if (!btf)
                 return -EINVAL;
 
         ret = btf_find_by_name_kind(btf, name, kind);
         /* ret is never zero, since btf_find_by_name_kind returns
          * positive btf_id or negative error.
          */
         if (ret > 0) {
                 btf_get(btf);
                 *btf_p = btf;
                 return ret;
         }
 
         /* If name is not found in vmlinux's BTF then search in module's BTFs */
         spin_lock_bh(&btf_idr_lock);
         idr_for_each_entry(&btf_idr, btf, id) {
                 if (!btf_is_module(btf))
                         continue;
                 /* linear search could be slow hence unlock/lock
                  * the IDR to avoiding holding it for too long
                  */
                 btf_get(btf);
                 spin_unlock_bh(&btf_idr_lock);
                 ret = btf_find_by_name_kind(btf, name, kind);
                 if (ret > 0) {
                         *btf_p = btf;
                         return ret;
                 }
                 btf_put(btf);
                 spin_lock_bh(&btf_idr_lock);
         }
         spin_unlock_bh(&btf_idr_lock);
         return ret;
 }
 
 const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
                                                u32 id, u32 *res_id)
 {
         const struct btf_type *t = btf_type_by_id(btf, id);
 
         while (btf_type_is_modifier(t)) {
                 id = t->type;
                 t = btf_type_by_id(btf, t->type);
         }
 
         if (res_id)
                 *res_id = id;
 
         return t;
 }
 
 const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
                                             u32 id, u32 *res_id)
 {
         const struct btf_type *t;
 
         t = btf_type_skip_modifiers(btf, id, NULL);
         if (!btf_type_is_ptr(t))
                 return NULL;
 
         return btf_type_skip_modifiers(btf, t->type, res_id);
 }
 
 const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
                                                  u32 id, u32 *res_id)
 {
         const struct btf_type *ptype;
 
         ptype = btf_type_resolve_ptr(btf, id, res_id);
         if (ptype && btf_type_is_func_proto(ptype))
                 return ptype;
 
         return NULL;
 }
 
 /* Types that act only as a source, not sink or intermediate
  * type when resolving.
  */
 static bool btf_type_is_resolve_source_only(const struct btf_type *t)
 {
         return btf_type_is_var(t) ||
                btf_type_is_decl_tag(t) ||
                btf_type_is_datasec(t);
 }
 
 /* What types need to be resolved?
  *
  * btf_type_is_modifier() is an obvious one.
  *
  * btf_type_is_struct() because its member refers to
  * another type (through member->type).
  *
  * btf_type_is_var() because the variable refers to
  * another type. btf_type_is_datasec() holds multiple
  * btf_type_is_var() types that need resolving.
  *
  * btf_type_is_array() because its element (array->type)
  * refers to another type.  Array can be thought of a
  * special case of struct while array just has the same
  * member-type repeated by array->nelems of times.
  */
 static bool btf_type_needs_resolve(const struct btf_type *t)
 {
         return btf_type_is_modifier(t) ||
                btf_type_is_ptr(t) ||
                btf_type_is_struct(t) ||
                btf_type_is_array(t) ||
                btf_type_is_var(t) ||
                btf_type_is_func(t) ||
                btf_type_is_decl_tag(t) ||
                btf_type_is_datasec(t);
 }
 
 /* t->size can be used */
 static bool btf_type_has_size(const struct btf_type *t)
 {
         switch (BTF_INFO_KIND(t->info)) {
         case BTF_KIND_INT:
         case BTF_KIND_STRUCT:
         case BTF_KIND_UNION:
         case BTF_KIND_ENUM:
         case BTF_KIND_DATASEC:
         case BTF_KIND_FLOAT:
         case BTF_KIND_ENUM64:
                 return true;
         }
 
         return false;
 }
 
 static const char *btf_int_encoding_str(u8 encoding)
 {
         if (encoding == 0)
                 return "(none)";
         else if (encoding == BTF_INT_SIGNED)
                 return "SIGNED";
         else if (encoding == BTF_INT_CHAR)
                 return "CHAR";
         else if (encoding == BTF_INT_BOOL)
                 return "BOOL";
         else
                 return "UNKN";
 }
 
 static u32 btf_type_int(const struct btf_type *t)
 {
         return *(u32 *)(t + 1);
 }
 
 static const struct btf_array *btf_type_array(const struct btf_type *t)
 {
         return (const struct btf_array *)(t + 1);
 }
 
 static const struct btf_enum *btf_type_enum(const struct btf_type *t)
 {
         return (const struct btf_enum *)(t + 1);
 }
 
 static const struct btf_var *btf_type_var(const struct btf_type *t)
 {
         return (const struct btf_var *)(t + 1);
 }
 
 static const struct btf_decl_tag *btf_type_decl_tag(const struct btf_type *t)
 {
         return (const struct btf_decl_tag *)(t + 1);
 }
 
 static const struct btf_enum64 *btf_type_enum64(const struct btf_type *t)
 {
         return (const struct btf_enum64 *)(t + 1);
 }
 
 static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
 {
         return kind_ops[BTF_INFO_KIND(t->info)];
 }
 
 static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
 {
         if (!BTF_STR_OFFSET_VALID(offset))
                 return false;
 
         while (offset < btf->start_str_off)
                 btf = btf->base_btf;
 
         offset -= btf->start_str_off;
         return offset < btf->hdr.str_len;
 }
 
 static bool __btf_name_char_ok(char c, bool first)
 {
         if ((first ? !isalpha(c) :
                      !isalnum(c)) &&
             c != '_' &&
             c != '.')
                 return false;
         return true;
 }
 
 const char *btf_str_by_offset(const struct btf *btf, u32 offset)
 {
         while (offset < btf->start_str_off)
                 btf = btf->base_btf;
 
         offset -= btf->start_str_off;
         if (offset < btf->hdr.str_len)
                 return &btf->strings[offset];
 
         return NULL;
 }
 
 static bool __btf_name_valid(const struct btf *btf, u32 offset)
 {
         /* offset must be valid */
         const char *src = btf_str_by_offset(btf, offset);
         const char *src_limit;
 
         if (!__btf_name_char_ok(*src, true))
                 return false;
 
         /* set a limit on identifier length */
         src_limit = src + KSYM_NAME_LEN;
         src++;
         while (*src && src < src_limit) {
                 if (!__btf_name_char_ok(*src, false))
                         return false;
                 src++;
         }
 
         return !*src;
 }
 
 static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
 {
         return __btf_name_valid(btf, offset);
 }
 
 /* Allow any printable character in DATASEC names */
 static bool btf_name_valid_section(const struct btf *btf, u32 offset)
 {
         /* offset must be valid */
         const char *src = btf_str_by_offset(btf, offset);
         const char *src_limit;
 
         if (!*src)
                 return false;
 
         /* set a limit on identifier length */
         src_limit = src + KSYM_NAME_LEN;
         while (*src && src < src_limit) {
                 if (!isprint(*src))
                         return false;
                 src++;
         }
 
         return !*src;
 }
 
 static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
 {
         const char *name;
 
         if (!offset)
                 return "(anon)";
 
         name = btf_str_by_offset(btf, offset);
         return name ?: "(invalid-name-offset)";
 }
 
 const char *btf_name_by_offset(const struct btf *btf, u32 offset)
 {
         return btf_str_by_offset(btf, offset);
 }
 
 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
 {
         while (type_id < btf->start_id)
                 btf = btf->base_btf;
 
         type_id -= btf->start_id;
         if (type_id >= btf->nr_types)
                 return NULL;
         return btf->types[type_id];
 }
 EXPORT_SYMBOL_GPL(btf_type_by_id);
 
 /*
  * Regular int is not a bit field and it must be either
  * u8/u16/u32/u64 or __int128.
  */
 static bool btf_type_int_is_regular(const struct btf_type *t)
 {
         u8 nr_bits, nr_bytes;
         u32 int_data;
 
         int_data = btf_type_int(t);
         nr_bits = BTF_INT_BITS(int_data);
         nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
         if (BITS_PER_BYTE_MASKED(nr_bits) ||
             BTF_INT_OFFSET(int_data) ||
             (nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
              nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) &&
              nr_bytes != (2 * sizeof(u64)))) {
                 return false;
         }
 
         return true;
 }
 
 /*
  * Check that given struct member is a regular int with expected
  * offset and size.
  */
 bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
                            const struct btf_member *m,
                            u32 expected_offset, u32 expected_size)
 {
         const struct btf_type *t;
         u32 id, int_data;
         u8 nr_bits;
 
         id = m->type;
         t = btf_type_id_size(btf, &id, NULL);
         if (!t || !btf_type_is_int(t))
                 return false;
 
         int_data = btf_type_int(t);
         nr_bits = BTF_INT_BITS(int_data);
         if (btf_type_kflag(s)) {
                 u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
                 u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);
 
                 /* if kflag set, int should be a regular int and
                  * bit offset should be at byte boundary.
                  */
                 return !bitfield_size &&
                        BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
                        BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
         }
 
         if (BTF_INT_OFFSET(int_data) ||
             BITS_PER_BYTE_MASKED(m->offset) ||
             BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
             BITS_PER_BYTE_MASKED(nr_bits) ||
             BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
                 return false;
 
         return true;
 }
 
 /* Similar to btf_type_skip_modifiers() but does not skip typedefs. */
 static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf,
                                                        u32 id)
 {
         const struct btf_type *t = btf_type_by_id(btf, id);
 
         while (btf_type_is_modifier(t) &&
                BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) {
                 t = btf_type_by_id(btf, t->type);
         }
 
         return t;
 }
 
 #define BTF_SHOW_MAX_ITER       10
 
 #define BTF_KIND_BIT(kind)      (1ULL << kind)
 
 /*
  * Populate show->state.name with type name information.
  * Format of type name is
  *
  * [.member_name = ] (type_name)
  */
 static const char *btf_show_name(struct btf_show *show)
 {
         /* BTF_MAX_ITER array suffixes "[]" */
         const char *array_suffixes = "[][][][][][][][][][]";
         const char *array_suffix = &array_suffixes[strlen(array_suffixes)];
         /* BTF_MAX_ITER pointer suffixes "*" */
         const char *ptr_suffixes = "**********";
         const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)];
         const char *name = NULL, *prefix = "", *parens = "";
         const struct btf_member *m = show->state.member;
         const struct btf_type *t;
         const struct btf_array *array;
         u32 id = show->state.type_id;
         const char *member = NULL;
         bool show_member = false;
         u64 kinds = 0;
         int i;
 
         show->state.name[0] = '\0';
 
         /*
          * Don't show type name if we're showing an array member;
          * in that case we show the array type so don't need to repeat
          * ourselves for each member.
          */
         if (show->state.array_member)
                 return "";
 
         /* Retrieve member name, if any. */
         if (m) {
                 member = btf_name_by_offset(show->btf, m->name_off);
                 show_member = strlen(member) > 0;
                 id = m->type;
         }
 
         /*
          * Start with type_id, as we have resolved the struct btf_type *
          * via btf_modifier_show() past the parent typedef to the child
          * struct, int etc it is defined as.  In such cases, the type_id
          * still represents the starting type while the struct btf_type *
          * in our show->state points at the resolved type of the typedef.
          */
         t = btf_type_by_id(show->btf, id);
         if (!t)
                 return "";
 
         /*
          * The goal here is to build up the right number of pointer and
          * array suffixes while ensuring the type name for a typedef
          * is represented.  Along the way we accumulate a list of
          * BTF kinds we have encountered, since these will inform later
          * display; for example, pointer types will not require an
          * opening "{" for struct, we will just display the pointer value.
          *
          * We also want to accumulate the right number of pointer or array
          * indices in the format string while iterating until we get to
          * the typedef/pointee/array member target type.
          *
          * We start by pointing at the end of pointer and array suffix
          * strings; as we accumulate pointers and arrays we move the pointer
          * or array string backwards so it will show the expected number of
          * '*' or '[]' for the type.  BTF_SHOW_MAX_ITER of nesting of pointers
          * and/or arrays and typedefs are supported as a precaution.
          *
          * We also want to get typedef name while proceeding to resolve
          * type it points to so that we can add parentheses if it is a
          * "typedef struct" etc.
          */
         for (i = 0; i < BTF_SHOW_MAX_ITER; i++) {
 
                 switch (BTF_INFO_KIND(t->info)) {
                 case BTF_KIND_TYPEDEF:
                         if (!name)
                                 name = btf_name_by_offset(show->btf,
                                                                t->name_off);
                         kinds |= BTF_KIND_BIT(BTF_KIND_TYPEDEF);
                         id = t->type;
                         break;
                 case BTF_KIND_ARRAY:
                         kinds |= BTF_KIND_BIT(BTF_KIND_ARRAY);
                         parens = "[";
                         if (!t)
                                 return "";
                         array = btf_type_array(t);
                         if (array_suffix > array_suffixes)
                                 array_suffix -= 2;
                         id = array->type;
                         break;
                 case BTF_KIND_PTR:
                         kinds |= BTF_KIND_BIT(BTF_KIND_PTR);
                         if (ptr_suffix > ptr_suffixes)
                                 ptr_suffix -= 1;
                         id = t->type;
                         break;
                 default:
                         id = 0;
                         break;
                 }
                 if (!id)
                         break;
                 t = btf_type_skip_qualifiers(show->btf, id);
         }
         /* We may not be able to represent this type; bail to be safe */
         if (i == BTF_SHOW_MAX_ITER)
                 return "";
 
         if (!name)
                 name = btf_name_by_offset(show->btf, t->name_off);
 
         switch (BTF_INFO_KIND(t->info)) {
         case BTF_KIND_STRUCT:
         case BTF_KIND_UNION:
                 prefix = BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT ?
                          "struct" : "union";
                 /* if it's an array of struct/union, parens is already set */
                 if (!(kinds & (BTF_KIND_BIT(BTF_KIND_ARRAY))))
                         parens = "{";
                 break;
         case BTF_KIND_ENUM:
         case BTF_KIND_ENUM64:
                 prefix = "enum";
                 break;
         default:
                 break;
         }
 
         /* pointer does not require parens */
         if (kinds & BTF_KIND_BIT(BTF_KIND_PTR))
                 parens = "";
         /* typedef does not require struct/union/enum prefix */
         if (kinds & BTF_KIND_BIT(BTF_KIND_TYPEDEF))
                 prefix = "";
 
         if (!name)
                 name = "";
 
         /* Even if we don't want type name info, we want parentheses etc */
         if (show->flags & BTF_SHOW_NONAME)
                 snprintf(show->state.name, sizeof(show->state.name), "%s",
                          parens);
         else
                 snprintf(show->state.name, sizeof(show->state.name),
                          "%s%s%s(%s%s%s%s%s%s)%s",
                          /* first 3 strings comprise ".member = " */
                          show_member ? "." : "",
                          show_member ? member : "",
                          show_member ? " = " : "",
                          /* ...next is our prefix (struct, enum, etc) */
                          prefix,
                          strlen(prefix) > 0 && strlen(name) > 0 ? " " : "",
                          /* ...this is the type name itself */
                          name,
                          /* ...suffixed by the appropriate '*', '[]' suffixes */
                          strlen(ptr_suffix) > 0 ? " " : "", ptr_suffix,
                          array_suffix, parens);
 
         return show->state.name;
 }
 
 static const char *__btf_show_indent(struct btf_show *show)
 {
         const char *indents = "                                ";
         const char *indent = &indents[strlen(indents)];
 
         if ((indent - show->state.depth) >= indents)
                 return indent - show->state.depth;
         return indents;
 }
 
 static const char *btf_show_indent(struct btf_show *show)
 {
         return show->flags & BTF_SHOW_COMPACT ? "" : __btf_show_indent(show);
 }
 
 static const char *btf_show_newline(struct btf_show *show)
 {
         return show->flags & BTF_SHOW_COMPACT ? "" : "\n";
 }
 
 static const char *btf_show_delim(struct btf_show *show)
 {
         if (show->state.depth == 0)
                 return "";
 
         if ((show->flags & BTF_SHOW_COMPACT) && show->state.type &&
                 BTF_INFO_KIND(show->state.type->info) == BTF_KIND_UNION)
                 return "|";
 
         return ",";
 }
 
 __printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...)
 {
         va_list args;
 
         if (!show->state.depth_check) {
                 va_start(args, fmt);
                 show->showfn(show, fmt, args);
                 va_end(args);
         }
 }
 
 /* Macros are used here as btf_show_type_value[s]() prepends and appends
  * format specifiers to the format specifier passed in; these do the work of
  * adding indentation, delimiters etc while the caller simply has to specify
  * the type value(s) in the format specifier + value(s).
  */
 #define btf_show_type_value(show, fmt, value)                                  \
         do {                                                                   \
                 if ((value) != (__typeof__(value))0 ||                         \
                     (show->flags & BTF_SHOW_ZERO) ||                           \
                     show->state.depth == 0) {                                  \
                         btf_show(show, "%s%s" fmt "%s%s",                      \
                                  btf_show_indent(show),                        \
                                  btf_show_name(show),                          \
                                  value, btf_show_delim(show),                  \
                                  btf_show_newline(show));                      \
                         if (show->state.depth > show->state.depth_to_show)     \
                                 show->state.depth_to_show = show->state.depth; \
                 }                                                              \
         } while (0)
 
 #define btf_show_type_values(show, fmt, ...)                                   \
         do {                                                                   \
                 btf_show(show, "%s%s" fmt "%s%s", btf_show_indent(show),       \
                          btf_show_name(show),                                  \
                          __VA_ARGS__, btf_show_delim(show),                    \
                          btf_show_newline(show));                              \
                 if (show->state.depth > show->state.depth_to_show)             \
                         show->state.depth_to_show = show->state.depth;         \
         } while (0)
 
 /* How much is left to copy to safe buffer after @data? */
 static int btf_show_obj_size_left(struct btf_show *show, void *data)
 {
         return show->obj.head + show->obj.size - data;
 }
 
 /* Is object pointed to by @data of @size already copied to our safe buffer? */
 static bool btf_show_obj_is_safe(struct btf_show *show, void *data, int size)
 {
         return data >= show->obj.data &&
                (data + size) < (show->obj.data + BTF_SHOW_OBJ_SAFE_SIZE);
 }
 
 /*
  * If object pointed to by @data of @size falls within our safe buffer, return
  * the equivalent pointer to the same safe data.  Assumes
  * copy_from_kernel_nofault() has already happened and our safe buffer is
  * populated.
  */
 static void *__btf_show_obj_safe(struct btf_show *show, void *data, int size)
 {
         if (btf_show_obj_is_safe(show, data, size))
                 return show->obj.safe + (data - show->obj.data);
         return NULL;
 }
 
 /*
  * Return a safe-to-access version of data pointed to by @data.
  * We do this by copying the relevant amount of information
  * to the struct btf_show obj.safe buffer using copy_from_kernel_nofault().
  *
  * If BTF_SHOW_UNSAFE is specified, just return data as-is; no
  * safe copy is needed.
  *
  * Otherwise we need to determine if we have the required amount
  * of data (determined by the @data pointer and the size of the
  * largest base type we can encounter (represented by
  * BTF_SHOW_OBJ_BASE_TYPE_SIZE). Having that much data ensures
  * that we will be able to print some of the current object,
  * and if more is needed a copy will be triggered.
  * Some objects such as structs will not fit into the buffer;
  * in such cases additional copies when we iterate over their
  * members may be needed.
  *
  * btf_show_obj_safe() is used to return a safe buffer for
  * btf_show_start_type(); this ensures that as we recurse into
  * nested types we always have safe data for the given type.
  * This approach is somewhat wasteful; it's possible for example
  * that when iterating over a large union we'll end up copying the
  * same data repeatedly, but the goal is safety not performance.
  * We use stack data as opposed to per-CPU buffers because the
  * iteration over a type can take some time, and preemption handling
  * would greatly complicate use of the safe buffer.
  */
 static void *btf_show_obj_safe(struct btf_show *show,
                                const struct btf_type *t,
                                void *data)
 {
         const struct btf_type *rt;
         int size_left, size;
         void *safe = NULL;
 
         if (show->flags & BTF_SHOW_UNSAFE)
                 return data;
 
         rt = btf_resolve_size(show->btf, t, &size);
         if (IS_ERR(rt)) {
                 show->state.status = PTR_ERR(rt);
                 return NULL;
         }
 
         /*
          * Is this toplevel object? If so, set total object size and
          * initialize pointers.  Otherwise check if we still fall within
          * our safe object data.
          */
         if (show->state.depth == 0) {
                 show->obj.size = size;
                 show->obj.head = data;
         } else {
                 /*
                  * If the size of the current object is > our remaining
                  * safe buffer we _may_ need to do a new copy.  However
                  * consider the case of a nested struct; it's size pushes
                  * us over the safe buffer limit, but showing any individual
                  * struct members does not.  In such cases, we don't need
                  * to initiate a fresh copy yet; however we definitely need
                  * at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes left
                  * in our buffer, regardless of the current object size.
                  * The logic here is that as we resolve types we will
                  * hit a base type at some point, and we need to be sure
                  * the next chunk of data is safely available to display
                  * that type info safely.  We cannot rely on the size of
                  * the current object here because it may be much larger
                  * than our current buffer (e.g. task_struct is 8k).
                  * All we want to do here is ensure that we can print the
                  * next basic type, which we can if either
                  * - the current type size is within the safe buffer; or
                  * - at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes are left in
                  *   the safe buffer.
                  */
                 safe = __btf_show_obj_safe(show, data,
                                            min(size,
                                                BTF_SHOW_OBJ_BASE_TYPE_SIZE));
         }
 
         /*
          * We need a new copy to our safe object, either because we haven't
          * yet copied and are initializing safe data, or because the data
          * we want falls outside the boundaries of the safe object.
          */
         if (!safe) {
                 size_left = btf_show_obj_size_left(show, data);
                 if (size_left > BTF_SHOW_OBJ_SAFE_SIZE)
                         size_left = BTF_SHOW_OBJ_SAFE_SIZE;
                 show->state.status = copy_from_kernel_nofault(show->obj.safe,
                                                               data, size_left);
                 if (!show->state.status) {
                         show->obj.data = data;
                         safe = show->obj.safe;
                 }
         }
 
         return safe;
 }
 
 /*
  * Set the type we are starting to show and return a safe data pointer
  * to be used for showing the associated data.
  */
 static void *btf_show_start_type(struct btf_show *show,
                                  const struct btf_type *t,
                                  u32 type_id, void *data)
 {
         show->state.type = t;
         show->state.type_id = type_id;
         show->state.name[0] = '\0';
 
         return btf_show_obj_safe(show, t, data);
 }
 
 static void btf_show_end_type(struct btf_show *show)
 {
         show->state.type = NULL;
         show->state.type_id = 0;
         show->state.name[0] = '\0';
 }
 
 static void *btf_show_start_aggr_type(struct btf_show *show,
                                       const struct btf_type *t,
                                       u32 type_id, void *data)
 {
         void *safe_data = btf_show_start_type(show, t, type_id, data);
 
         if (!safe_data)
                 return safe_data;
 
         btf_show(show, "%s%s%s", btf_show_indent(show),
                  btf_show_name(show),
                  btf_show_newline(show));
         show->state.depth++;
         return safe_data;
 }
 
 static void btf_show_end_aggr_type(struct btf_show *show,
                                    const char *suffix)
 {
         show->state.depth--;
         btf_show(show, "%s%s%s%s", btf_show_indent(show), suffix,
                  btf_show_delim(show), btf_show_newline(show));
         btf_show_end_type(show);
 }
 
 static void btf_show_start_member(struct btf_show *show,
                                   const struct btf_member *m)
 {
         show->state.member = m;
 }
 
 static void btf_show_start_array_member(struct btf_show *show)
 {
         show->state.array_member = 1;
         btf_show_start_member(show, NULL);
 }
 
 static void btf_show_end_member(struct btf_show *show)
 {
         show->state.member = NULL;
 }
 
 static void btf_show_end_array_member(struct btf_show *show)
 {
         show->state.array_member = 0;
         btf_show_end_member(show);
 }
 
 static void *btf_show_start_array_type(struct btf_show *show,
                                        const struct btf_type *t,
                                        u32 type_id,
                                        u16 array_encoding,
                                        void *data)
 {
         show->state.array_encoding = array_encoding;
         show->state.array_terminated = 0;
         return btf_show_start_aggr_type(show, t, type_id, data);
 }
 
 static void btf_show_end_array_type(struct btf_show *show)
 {
         show->state.array_encoding = 0;
         show->state.array_terminated = 0;
         btf_show_end_aggr_type(show, "]");
 }
 
 static void *btf_show_start_struct_type(struct btf_show *show,
                                         const struct btf_type *t,
                                         u32 type_id,
                                         void *data)
 {
         return btf_show_start_aggr_type(show, t, type_id, data);
 }
 
 static void btf_show_end_struct_type(struct btf_show *show)
 {
         btf_show_end_aggr_type(show, "}");
 }
 
 __printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
                                               const char *fmt, ...)
 {
         va_list args;
 
         va_start(args, fmt);
         bpf_verifier_vlog(log, fmt, args);
         va_end(args);
 }
 
 __printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
                                             const char *fmt, ...)
 {
         struct bpf_verifier_log *log = &env->log;
         va_list args;
 
         if (!bpf_verifier_log_needed(log))
                 return;
 
         va_start(args, fmt);
         bpf_verifier_vlog(log, fmt, args);
         va_end(args);
 }
 
 __printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
                                                    const struct btf_type *t,
                                                    bool log_details,
                                                    const char *fmt, ...)
 {
         struct bpf_verifier_log *log = &env->log;
         struct btf *btf = env->btf;
         va_list args;
 
         if (!bpf_verifier_log_needed(log))
                 return;
 
         if (log->level == BPF_LOG_KERNEL) {
                 /* btf verifier prints all types it is processing via
                  * btf_verifier_log_type(..., fmt = NULL).
                  * Skip those prints for in-kernel BTF verification.
                  */
                 if (!fmt)
                         return;
 
                 /* Skip logging when loading module BTF with mismatches permitted */
                 if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
                         return;
         }
 
         __btf_verifier_log(log, "[%u] %s %s%s",
                            env->log_type_id,
                            btf_type_str(t),
                            __btf_name_by_offset(btf, t->name_off),
                            log_details ? " " : "");
 
         if (log_details)
                 btf_type_ops(t)->log_details(env, t);
 
         if (fmt && *fmt) {
                 __btf_verifier_log(log, " ");
                 va_start(args, fmt);
                 bpf_verifier_vlog(log, fmt, args);
                 va_end(args);
         }
 
         __btf_verifier_log(log, "\n");
 }
 
 #define btf_verifier_log_type(env, t, ...) \
         __btf_verifier_log_type((env), (t), true, __VA_ARGS__)
 #define btf_verifier_log_basic(env, t, ...) \
         __btf_verifier_log_type((env), (t), false, __VA_ARGS__)
 
 __printf(4, 5)
 static void btf_verifier_log_member(struct btf_verifier_env *env,
                                     const struct btf_type *struct_type,
                                     const struct btf_member *member,
                                     const char *fmt, ...)
 {
         struct bpf_verifier_log *log = &env->log;
         struct btf *btf = env->btf;
         va_list args;
 
         if (!bpf_verifier_log_needed(log))
                 return;
 
         if (log->level == BPF_LOG_KERNEL) {
                 if (!fmt)
                         return;
 
                 /* Skip logging when loading module BTF with mismatches permitted */
                 if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
                         return;
         }
 
         /* The CHECK_META phase already did a btf dump.
          *
          * If member is logged again, it must hit an error in
          * parsing this member.  It is useful to print out which
          * struct this member belongs to.
          */
         if (env->phase != CHECK_META)
                 btf_verifier_log_type(env, struct_type, NULL);
 
         if (btf_type_kflag(struct_type))
                 __btf_verifier_log(log,
                                    "\t%s type_id=%u bitfield_size=%u bits_offset=%u",
                                    __btf_name_by_offset(btf, member->name_off),
                                    member->type,
                                    BTF_MEMBER_BITFIELD_SIZE(member->offset),
                                    BTF_MEMBER_BIT_OFFSET(member->offset));
         else
                 __btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
                                    __btf_name_by_offset(btf, member->name_off),
                                    member->type, member->offset);
 
         if (fmt && *fmt) {
                 __btf_verifier_log(log, " ");
                 va_start(args, fmt);
                 bpf_verifier_vlog(log, fmt, args);
                 va_end(args);
         }
 
         __btf_verifier_log(log, "\n");
 }
 
 __printf(4, 5)
 static void btf_verifier_log_vsi(struct btf_verifier_env *env,
                                  const struct btf_type *datasec_type,
                                  const struct btf_var_secinfo *vsi,
                                  const char *fmt, ...)
 {
         struct bpf_verifier_log *log = &env->log;
         va_list args;
 
         if (!bpf_verifier_log_needed(log))
                 return;
         if (log->level == BPF_LOG_KERNEL && !fmt)
                 return;
         if (env->phase != CHECK_META)
                 btf_verifier_log_type(env, datasec_type, NULL);
 
         __btf_verifier_log(log, "\t type_id=%u offset=%u size=%u",
                            vsi->type, vsi->offset, vsi->size);
         if (fmt && *fmt) {
                 __btf_verifier_log(log, " ");
                 va_start(args, fmt);
                 bpf_verifier_vlog(log, fmt, args);
                 va_end(args);
         }
 
         __btf_verifier_log(log, "\n");
 }
 
 static void btf_verifier_log_hdr(struct btf_verifier_env *env,
                                  u32 btf_data_size)
 {
         struct bpf_verifier_log *log = &env->log;
         const struct btf *btf = env->btf;
         const struct btf_header *hdr;
 
         if (!bpf_verifier_log_needed(log))
                 return;
 
         if (log->level == BPF_LOG_KERNEL)
                 return;
         hdr = &btf->hdr;
         __btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
         __btf_verifier_log(log, "version: %u\n", hdr->version);
         __btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
         __btf_verifier_log(log, "hdr_len: %u\n", hdr->hdr_len);
         __btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
         __btf_verifier_log(log, "type_len: %u\n", hdr->type_len);
         __btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
         __btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
         __btf_verifier_log(log, "btf_total_size: %u\n", btf_data_size);
 }
 
 static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
 {
         struct btf *btf = env->btf;
 
         if (btf->types_size == btf->nr_types) {
                 /* Expand 'types' array */
 
                 struct btf_type **new_types;
                 u32 expand_by, new_size;
 
                 if (btf->start_id + btf->types_size == BTF_MAX_TYPE) {
                         btf_verifier_log(env, "Exceeded max num of types");
                         return -E2BIG;
                 }
 
                 expand_by = max_t(u32, btf->types_size >> 2, 16);
                 new_size = min_t(u32, BTF_MAX_TYPE,
                                  btf->types_size + expand_by);
 
                 new_types = kvcalloc(new_size, sizeof(*new_types),
                                      GFP_KERNEL | __GFP_NOWARN);
                 if (!new_types)
                         return -ENOMEM;
 
                 if (btf->nr_types == 0) {
                         if (!btf->base_btf) {
                                 /* lazily init VOID type */
                                 new_types[0] = &btf_void;
                                 btf->nr_types++;
                         }
                 } else {
                         memcpy(new_types, btf->types,
                                sizeof(*btf->types) * btf->nr_types);
                 }
 
                 kvfree(btf->types);
                 btf->types = new_types;
                 btf->types_size = new_size;
         }
 
         btf->types[btf->nr_types++] = t;
 
         return 0;
 }
 
 static int btf_alloc_id(struct btf *btf)
 {
         int id;
 
         idr_preload(GFP_KERNEL);
         spin_lock_bh(&btf_idr_lock);
         id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
         if (id > 0)
                 btf->id = id;
         spin_unlock_bh(&btf_idr_lock);
         idr_preload_end();
 
         if (WARN_ON_ONCE(!id))
                 return -ENOSPC;
 
         return id > 0 ? 0 : id;
 }
 
 static void btf_free_id(struct btf *btf)
 {
         unsigned long flags;
 
         /*
          * In map-in-map, calling map_delete_elem() on outer
          * map will call bpf_map_put on the inner map.
          * It will then eventually call btf_free_id()
          * on the inner map.  Some of the map_delete_elem()
          * implementation may have irq disabled, so
          * we need to use the _irqsave() version instead
          * of the _bh() version.
          */
         spin_lock_irqsave(&btf_idr_lock, flags);
         idr_remove(&btf_idr, btf->id);
         spin_unlock_irqrestore(&btf_idr_lock, flags);
 }
 
 static void btf_free_kfunc_set_tab(struct btf *btf)
 {
         struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab;
         int hook;
 
         if (!tab)
                 return;
         for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++)
                 kfree(tab->sets[hook]);
         kfree(tab);
         btf->kfunc_set_tab = NULL;
 }
 
 static void btf_free_dtor_kfunc_tab(struct btf *btf)
 {
         struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
 
         if (!tab)
                 return;
         kfree(tab);
         btf->dtor_kfunc_tab = NULL;
 }
 
 static void btf_struct_metas_free(struct btf_struct_metas *tab)
 {
         int i;
 
         if (!tab)
                 return;
         for (i = 0; i < tab->cnt; i++)
                 btf_record_free(tab->types[i].record);
         kfree(tab);
 }
 
 static void btf_free_struct_meta_tab(struct btf *btf)
 {
         struct btf_struct_metas *tab = btf->struct_meta_tab;
 
         btf_struct_metas_free(tab);
         btf->struct_meta_tab = NULL;
 }
 
 static void btf_free_struct_ops_tab(struct btf *btf)
 {
         struct btf_struct_ops_tab *tab = btf->struct_ops_tab;
         u32 i;
 
         if (!tab)
                 return;
 
         for (i = 0; i < tab->cnt; i++)
                 bpf_struct_ops_desc_release(&tab->ops[i]);
 
         kfree(tab);
         btf->struct_ops_tab = NULL;
 }
 
 static void btf_free(struct btf *btf)
 {
         btf_free_struct_meta_tab(btf);
         btf_free_dtor_kfunc_tab(btf);
         btf_free_kfunc_set_tab(btf);
         btf_free_struct_ops_tab(btf);
         kvfree(btf->types);
         kvfree(btf->resolved_sizes);
         kvfree(btf->resolved_ids);
         /* vmlinux does not allocate btf->data, it simply points it at
          * __start_BTF.
          */
         if (!btf_is_vmlinux(btf))
                 kvfree(btf->data);
         kvfree(btf->base_id_map);
         kfree(btf);
 }
 
 static void btf_free_rcu(struct rcu_head *rcu)
 {
         struct btf *btf = container_of(rcu, struct btf, rcu);
 
         btf_free(btf);
 }
 
 const char *btf_get_name(const struct btf *btf)
 {
         return btf->name;
 }
 
 void btf_get(struct btf *btf)
 {
         refcount_inc(&btf->refcnt);
 }
 
 void btf_put(struct btf *btf)
 {
         if (btf && refcount_dec_and_test(&btf->refcnt)) {
                 btf_free_id(btf);
                 call_rcu(&btf->rcu, btf_free_rcu);
         }
 }
 
 struct btf *btf_base_btf(const struct btf *btf)
 {
         return btf->base_btf;
 }
 
 const struct btf_header *btf_header(const struct btf *btf)
 {
         return &btf->hdr;
 }
 
 void btf_set_base_btf(struct btf *btf, const struct btf *base_btf)
 {
         btf->base_btf = (struct btf *)base_btf;
         btf->start_id = btf_nr_types(base_btf);
         btf->start_str_off = base_btf->hdr.str_len;
 }
 
 static int env_resolve_init(struct btf_verifier_env *env)
 {
         struct btf *btf = env->btf;
         u32 nr_types = btf->nr_types;
         u32 *resolved_sizes = NULL;
         u32 *resolved_ids = NULL;
         u8 *visit_states = NULL;
 
         resolved_sizes = kvcalloc(nr_types, sizeof(*resolved_sizes),
                                   GFP_KERNEL | __GFP_NOWARN);
         if (!resolved_sizes)
                 goto nomem;
 
         resolved_ids = kvcalloc(nr_types, sizeof(*resolved_ids),
                                 GFP_KERNEL | __GFP_NOWARN);
         if (!resolved_ids)
                 goto nomem;
 
         visit_states = kvcalloc(nr_types, sizeof(*visit_states),
                                 GFP_KERNEL | __GFP_NOWARN);
         if (!visit_states)
                 goto nomem;
 
         btf->resolved_sizes = resolved_sizes;
         btf->resolved_ids = resolved_ids;
         env->visit_states = visit_states;
 
         return 0;
 
 nomem:
         kvfree(resolved_sizes);
         kvfree(resolved_ids);
         kvfree(visit_states);
         return -ENOMEM;
 }
 
 static void btf_verifier_env_free(struct btf_verifier_env *env)
 {
         kvfree(env->visit_states);
         kfree(env);
 }
 
 static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
                                      const struct btf_type *next_type)
 {
         switch (env->resolve_mode) {
         case RESOLVE_TBD:
                 /* int, enum or void is a sink */
                 return !btf_type_needs_resolve(next_type);
         case RESOLVE_PTR:
                 /* int, enum, void, struct, array, func or func_proto is a sink
                  * for ptr
                  */
                 return !btf_type_is_modifier(next_type) &&
                         !btf_type_is_ptr(next_type);
         case RESOLVE_STRUCT_OR_ARRAY:
                 /* int, enum, void, ptr, func or func_proto is a sink
                  * for struct and array
                  */
                 return !btf_type_is_modifier(next_type) &&
                         !btf_type_is_array(next_type) &&
                         !btf_type_is_struct(next_type);
         default:
                 BUG();
         }
 }
 
 static bool env_type_is_resolved(const struct btf_verifier_env *env,
                                  u32 type_id)
 {
         /* base BTF types should be resolved by now */
         if (type_id < env->btf->start_id)
                 return true;
 
         return env->visit_states[type_id - env->btf->start_id] == RESOLVED;
 }
 
 static int env_stack_push(struct btf_verifier_env *env,
                           const struct btf_type *t, u32 type_id)
 {
         const struct btf *btf = env->btf;
         struct resolve_vertex *v;
 
         if (env->top_stack == MAX_RESOLVE_DEPTH)
                 return -E2BIG;
 
         if (type_id < btf->start_id
             || env->visit_states[type_id - btf->start_id] != NOT_VISITED)
                 return -EEXIST;
 
         env->visit_states[type_id - btf->start_id] = VISITED;
 
         v = &env->stack[env->top_stack++];
         v->t = t;
         v->type_id = type_id;
         v->next_member = 0;
 
         if (env->resolve_mode == RESOLVE_TBD) {
                 if (btf_type_is_ptr(t))
                         env->resolve_mode = RESOLVE_PTR;
                 else if (btf_type_is_struct(t) || btf_type_is_array(t))
                         env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
         }
 
         return 0;
 }
 
 static void env_stack_set_next_member(struct btf_verifier_env *env,
                                       u16 next_member)
 {
         env->stack[env->top_stack - 1].next_member = next_member;
 }
 
 static void env_stack_pop_resolved(struct btf_verifier_env *env,
                                    u32 resolved_type_id,
                                    u32 resolved_size)
 {
         u32 type_id = env->stack[--(env->top_stack)].type_id;
         struct btf *btf = env->btf;
 
         type_id -= btf->start_id; /* adjust to local type id */
         btf->resolved_sizes[type_id] = resolved_size;
         btf->resolved_ids[type_id] = resolved_type_id;
         env->visit_states[type_id] = RESOLVED;
 }
 
 static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
 {
         return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
 }
 
 /* Resolve the size of a passed-in "type"
  *
  * type: is an array (e.g. u32 array[x][y])
  * return type: type "u32[x][y]", i.e. BTF_KIND_ARRAY,
  * *type_size: (x * y * sizeof(u32)).  Hence, *type_size always
  *             corresponds to the return type.
  * *elem_type: u32
  * *elem_id: id of u32
  * *total_nelems: (x * y).  Hence, individual elem size is
  *                (*type_size / *total_nelems)
  * *type_id: id of type if it's changed within the function, 0 if not
  *
  * type: is not an array (e.g. const struct X)
  * return type: type "struct X"
  * *type_size: sizeof(struct X)
  * *elem_type: same as return type ("struct X")
  * *elem_id: 0
  * *total_nelems: 1
  * *type_id: id of type if it's changed within the function, 0 if not
  */
 static const struct btf_type *
 __btf_resolve_size(const struct btf *btf, const struct btf_type *type,
                    u32 *type_size, const struct btf_type **elem_type,
                    u32 *elem_id, u32 *total_nelems, u32 *type_id)
 {
         const struct btf_type *array_type = NULL;
         const struct btf_array *array = NULL;
         u32 i, size, nelems = 1, id = 0;
 
         for (i = 0; i < MAX_RESOLVE_DEPTH; i++) {
                 switch (BTF_INFO_KIND(type->info)) {
                 /* type->size can be used */
                 case BTF_KIND_INT:
                 case BTF_KIND_STRUCT:
                 case BTF_KIND_UNION:
                 case BTF_KIND_ENUM:
                 case BTF_KIND_FLOAT:
                 case BTF_KIND_ENUM64:
                         size = type->size;
                         goto resolved;
 
                 case BTF_KIND_PTR:
                         size = sizeof(void *);
                         goto resolved;
 
                 /* Modifiers */
                 case BTF_KIND_TYPEDEF:
                 case BTF_KIND_VOLATILE:
                 case BTF_KIND_CONST:
                 case BTF_KIND_RESTRICT:
                 case BTF_KIND_TYPE_TAG:
                         id = type->type;
                         type = btf_type_by_id(btf, type->type);
                         break;
 
                 case BTF_KIND_ARRAY:
                         if (!array_type)
                                 array_type = type;
                         array = btf_type_array(type);
                         if (nelems && array->nelems > U32_MAX / nelems)
                                 return ERR_PTR(-EINVAL);
                         nelems *= array->nelems;
                         type = btf_type_by_id(btf, array->type);
                         break;
 
                 /* type without size */
                 default:
                         return ERR_PTR(-EINVAL);
                 }
         }
 
         return ERR_PTR(-EINVAL);
 
 resolved:
         if (nelems && size > U32_MAX / nelems)
                 return ERR_PTR(-EINVAL);
 
         *type_size = nelems * size;
         if (total_nelems)
                 *total_nelems = nelems;
         if (elem_type)
                 *elem_type = type;
         if (elem_id)
                 *elem_id = array ? array->type : 0;
         if (type_id && id)
                 *type_id = id;
 
         return array_type ? : type;
 }
 
 const struct btf_type *
 btf_resolve_size(const struct btf *btf, const struct btf_type *type,
                  u32 *type_size)
 {
         return __btf_resolve_size(btf, type, type_size, NULL, NULL, NULL, NULL);
 }
 
 static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id)
 {
         while (type_id < btf->start_id)
                 btf = btf->base_btf;
 
         return btf->resolved_ids[type_id - btf->start_id];
 }
 
 /* The input param "type_id" must point to a needs_resolve type */
 static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
                                                   u32 *type_id)
 {
         *type_id = btf_resolved_type_id(btf, *type_id);
         return btf_type_by_id(btf, *type_id);
 }
 
 static u32 btf_resolved_type_size(const struct btf *btf, u32 type_id)
 {
         while (type_id < btf->start_id)
                 btf = btf->base_btf;
 
         return btf->resolved_sizes[type_id - btf->start_id];
 }
 
 const struct btf_type *btf_type_id_size(const struct btf *btf,
                                         u32 *type_id, u32 *ret_size)
 {
         const struct btf_type *size_type;
         u32 size_type_id = *type_id;
         u32 size = 0;
 
         size_type = btf_type_by_id(btf, size_type_id);
         if (btf_type_nosize_or_null(size_type))
                 return NULL;
 
         if (btf_type_has_size(size_type)) {
                 size = size_type->size;
         } else if (btf_type_is_array(size_type)) {
                 size = btf_resolved_type_size(btf, size_type_id);
         } else if (btf_type_is_ptr(size_type)) {
                 size = sizeof(void *);
         } else {
                 if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
                                  !btf_type_is_var(size_type)))
                         return NULL;
 
                 size_type_id = btf_resolved_type_id(btf, size_type_id);
                 size_type = btf_type_by_id(btf, size_type_id);
                 if (btf_type_nosize_or_null(size_type))
                         return NULL;
                 else if (btf_type_has_size(size_type))
                         size = size_type->size;
                 else if (btf_type_is_array(size_type))
                         size = btf_resolved_type_size(btf, size_type_id);
                 else if (btf_type_is_ptr(size_type))
                         size = sizeof(void *);
                 else
                         return NULL;
         }
 
         *type_id = size_type_id;
         if (ret_size)
                 *ret_size = size;
 
         return size_type;
 }
 
 static int btf_df_check_member(struct btf_verifier_env *env,
                                const struct btf_type *struct_type,
                                const struct btf_member *member,
                                const struct btf_type *member_type)
 {
         btf_verifier_log_basic(env, struct_type,
                                "Unsupported check_member");
         return -EINVAL;
 }
 
 static int btf_df_check_kflag_member(struct btf_verifier_env *env,
                                      const struct btf_type *struct_type,
                                      const struct btf_member *member,
                                      const struct btf_type *member_type)
 {
         btf_verifier_log_basic(env, struct_type,
                                "Unsupported check_kflag_member");
         return -EINVAL;
 }
 
 /* Used for ptr, array struct/union and float type members.
  * int, enum and modifier types have their specific callback functions.
  */
 static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
                                           const struct btf_type *struct_type,
                                           const struct btf_member *member,
                                           const struct btf_type *member_type)
 {
         if (BTF_MEMBER_BITFIELD_SIZE(member->offset)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Invalid member bitfield_size");
                 return -EINVAL;
         }
 
         /* bitfield size is 0, so member->offset represents bit offset only.
          * It is safe to call non kflag check_member variants.
          */
         return btf_type_ops(member_type)->check_member(env, struct_type,
                                                        member,
                                                        member_type);
 }
 
 static int btf_df_resolve(struct btf_verifier_env *env,
                           const struct resolve_vertex *v)
 {
         btf_verifier_log_basic(env, v->t, "Unsupported resolve");
         return -EINVAL;
 }
 
 static void btf_df_show(const struct btf *btf, const struct btf_type *t,
                         u32 type_id, void *data, u8 bits_offsets,
                         struct btf_show *show)
 {
         btf_show(show, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
 }
 
 static int btf_int_check_member(struct btf_verifier_env *env,
                                 const struct btf_type *struct_type,
                                 const struct btf_member *member,
                                 const struct btf_type *member_type)
 {
         u32 int_data = btf_type_int(member_type);
         u32 struct_bits_off = member->offset;
         u32 struct_size = struct_type->size;
         u32 nr_copy_bits;
         u32 bytes_offset;
 
         if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "bits_offset exceeds U32_MAX");
                 return -EINVAL;
         }
 
         struct_bits_off += BTF_INT_OFFSET(int_data);
         bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
         nr_copy_bits = BTF_INT_BITS(int_data) +
                 BITS_PER_BYTE_MASKED(struct_bits_off);
 
         if (nr_copy_bits > BITS_PER_U128) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "nr_copy_bits exceeds 128");
                 return -EINVAL;
         }
 
         if (struct_size < bytes_offset ||
             struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static int btf_int_check_kflag_member(struct btf_verifier_env *env,
                                       const struct btf_type *struct_type,
                                       const struct btf_member *member,
                                       const struct btf_type *member_type)
 {
         u32 struct_bits_off, nr_bits, nr_int_data_bits, bytes_offset;
         u32 int_data = btf_type_int(member_type);
         u32 struct_size = struct_type->size;
         u32 nr_copy_bits;
 
         /* a regular int type is required for the kflag int member */
         if (!btf_type_int_is_regular(member_type)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Invalid member base type");
                 return -EINVAL;
         }
 
         /* check sanity of bitfield size */
         nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
         struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
         nr_int_data_bits = BTF_INT_BITS(int_data);
         if (!nr_bits) {
                 /* Not a bitfield member, member offset must be at byte
                  * boundary.
                  */
                 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                         btf_verifier_log_member(env, struct_type, member,
                                                 "Invalid member offset");
                         return -EINVAL;
                 }
 
                 nr_bits = nr_int_data_bits;
         } else if (nr_bits > nr_int_data_bits) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Invalid member bitfield_size");
                 return -EINVAL;
         }
 
         bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
         nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
         if (nr_copy_bits > BITS_PER_U128) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "nr_copy_bits exceeds 128");
                 return -EINVAL;
         }
 
         if (struct_size < bytes_offset ||
             struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static s32 btf_int_check_meta(struct btf_verifier_env *env,
                               const struct btf_type *t,
                               u32 meta_left)
 {
         u32 int_data, nr_bits, meta_needed = sizeof(int_data);
         u16 encoding;
 
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         if (btf_type_vlen(t)) {
                 btf_verifier_log_type(env, t, "vlen != 0");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         int_data = btf_type_int(t);
         if (int_data & ~BTF_INT_MASK) {
                 btf_verifier_log_basic(env, t, "Invalid int_data:%x",
                                        int_data);
                 return -EINVAL;
         }
 
         nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);
 
         if (nr_bits > BITS_PER_U128) {
                 btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
                                       BITS_PER_U128);
                 return -EINVAL;
         }
 
         if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
                 btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
                 return -EINVAL;
         }
 
         /*
          * Only one of the encoding bits is allowed and it
          * should be sufficient for the pretty print purpose (i.e. decoding).
          * Multiple bits can be allowed later if it is found
          * to be insufficient.
          */
         encoding = BTF_INT_ENCODING(int_data);
         if (encoding &&
             encoding != BTF_INT_SIGNED &&
             encoding != BTF_INT_CHAR &&
             encoding != BTF_INT_BOOL) {
                 btf_verifier_log_type(env, t, "Unsupported encoding");
                 return -ENOTSUPP;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return meta_needed;
 }
 
 static void btf_int_log(struct btf_verifier_env *env,
                         const struct btf_type *t)
 {
         int int_data = btf_type_int(t);
 
         btf_verifier_log(env,
                          "size=%u bits_offset=%u nr_bits=%u encoding=%s",
                          t->size, BTF_INT_OFFSET(int_data),
                          BTF_INT_BITS(int_data),
                          btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
 }
 
 static void btf_int128_print(struct btf_show *show, void *data)
 {
         /* data points to a __int128 number.
          * Suppose
          *     int128_num = *(__int128 *)data;
          * The below formulas shows what upper_num and lower_num represents:
          *     upper_num = int128_num >> 64;
          *     lower_num = int128_num & 0xffffffffFFFFFFFFULL;
          */
         u64 upper_num, lower_num;
 
 #ifdef __BIG_ENDIAN_BITFIELD
         upper_num = *(u64 *)data;
         lower_num = *(u64 *)(data + 8);
 #else
         upper_num = *(u64 *)(data + 8);
         lower_num = *(u64 *)data;
 #endif
         if (upper_num == 0)
                 btf_show_type_value(show, "0x%llx", lower_num);
         else
                 btf_show_type_values(show, "0x%llx%016llx", upper_num,
                                      lower_num);
 }
 
 static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
                              u16 right_shift_bits)
 {
         u64 upper_num, lower_num;
 
 #ifdef __BIG_ENDIAN_BITFIELD
         upper_num = print_num[0];
         lower_num = print_num[1];
 #else
         upper_num = print_num[1];
         lower_num = print_num[0];
 #endif
 
         /* shake out un-needed bits by shift/or operations */
         if (left_shift_bits >= 64) {
                 upper_num = lower_num << (left_shift_bits - 64);
                 lower_num = 0;
         } else {
                 upper_num = (upper_num << left_shift_bits) |
                             (lower_num >> (64 - left_shift_bits));
                 lower_num = lower_num << left_shift_bits;
         }
 
         if (right_shift_bits >= 64) {
                 lower_num = upper_num >> (right_shift_bits - 64);
                 upper_num = 0;
         } else {
                 lower_num = (lower_num >> right_shift_bits) |
                             (upper_num << (64 - right_shift_bits));
                 upper_num = upper_num >> right_shift_bits;
         }
 
 #ifdef __BIG_ENDIAN_BITFIELD
         print_num[0] = upper_num;
         print_num[1] = lower_num;
 #else
         print_num[0] = lower_num;
         print_num[1] = upper_num;
 #endif
 }
 
 static void btf_bitfield_show(void *data, u8 bits_offset,
                               u8 nr_bits, struct btf_show *show)
 {
         u16 left_shift_bits, right_shift_bits;
         u8 nr_copy_bytes;
         u8 nr_copy_bits;
         u64 print_num[2] = {};
 
         nr_copy_bits = nr_bits + bits_offset;
         nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);
 
         memcpy(print_num, data, nr_copy_bytes);
 
 #ifdef __BIG_ENDIAN_BITFIELD
         left_shift_bits = bits_offset;
 #else
         left_shift_bits = BITS_PER_U128 - nr_copy_bits;
 #endif
         right_shift_bits = BITS_PER_U128 - nr_bits;
 
         btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
         btf_int128_print(show, print_num);
 }
 
 
 static void btf_int_bits_show(const struct btf *btf,
                               const struct btf_type *t,
                               void *data, u8 bits_offset,
                               struct btf_show *show)
 {
         u32 int_data = btf_type_int(t);
         u8 nr_bits = BTF_INT_BITS(int_data);
         u8 total_bits_offset;
 
         /*
          * bits_offset is at most 7.
          * BTF_INT_OFFSET() cannot exceed 128 bits.
          */
         total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
         data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
         bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
         btf_bitfield_show(data, bits_offset, nr_bits, show);
 }
 
 static void btf_int_show(const struct btf *btf, const struct btf_type *t,
                          u32 type_id, void *data, u8 bits_offset,
                          struct btf_show *show)
 {
         u32 int_data = btf_type_int(t);
         u8 encoding = BTF_INT_ENCODING(int_data);
         bool sign = encoding & BTF_INT_SIGNED;
         u8 nr_bits = BTF_INT_BITS(int_data);
         void *safe_data;
 
         safe_data = btf_show_start_type(show, t, type_id, data);
         if (!safe_data)
                 return;
 
         if (bits_offset || BTF_INT_OFFSET(int_data) ||
             BITS_PER_BYTE_MASKED(nr_bits)) {
                 btf_int_bits_show(btf, t, safe_data, bits_offset, show);
                 goto out;
         }
 
         switch (nr_bits) {
         case 128:
                 btf_int128_print(show, safe_data);
                 break;
         case 64:
                 if (sign)
                         btf_show_type_value(show, "%lld", *(s64 *)safe_data);
                 else
                         btf_show_type_value(show, "%llu", *(u64 *)safe_data);
                 break;
         case 32:
                 if (sign)
                         btf_show_type_value(show, "%d", *(s32 *)safe_data);
                 else
                         btf_show_type_value(show, "%u", *(u32 *)safe_data);
                 break;
         case 16:
                 if (sign)
                         btf_show_type_value(show, "%d", *(s16 *)safe_data);
                 else
                         btf_show_type_value(show, "%u", *(u16 *)safe_data);
                 break;
         case 8:
                 if (show->state.array_encoding == BTF_INT_CHAR) {
                         /* check for null terminator */
                         if (show->state.array_terminated)
                                 break;
                         if (*(char *)data == '\0') {
                                 show->state.array_terminated = 1;
                                 break;
                         }
                         if (isprint(*(char *)data)) {
                                 btf_show_type_value(show, "'%c'",
                                                     *(char *)safe_data);
                                 break;
                         }
                 }
                 if (sign)
                         btf_show_type_value(show, "%d", *(s8 *)safe_data);
                 else
                         btf_show_type_value(show, "%u", *(u8 *)safe_data);
                 break;
         default:
                 btf_int_bits_show(btf, t, safe_data, bits_offset, show);
                 break;
         }
 out:
         btf_show_end_type(show);
 }
 
 static const struct btf_kind_operations int_ops = {
         .check_meta = btf_int_check_meta,
         .resolve = btf_df_resolve,
         .check_member = btf_int_check_member,
         .check_kflag_member = btf_int_check_kflag_member,
         .log_details = btf_int_log,
         .show = btf_int_show,
 };
 
 static int btf_modifier_check_member(struct btf_verifier_env *env,
                                      const struct btf_type *struct_type,
                                      const struct btf_member *member,
                                      const struct btf_type *member_type)
 {
         const struct btf_type *resolved_type;
         u32 resolved_type_id = member->type;
         struct btf_member resolved_member;
         struct btf *btf = env->btf;
 
         resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
         if (!resolved_type) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Invalid member");
                 return -EINVAL;
         }
 
         resolved_member = *member;
         resolved_member.type = resolved_type_id;
 
         return btf_type_ops(resolved_type)->check_member(env, struct_type,
                                                          &resolved_member,
                                                          resolved_type);
 }
 
 static int btf_modifier_check_kflag_member(struct btf_verifier_env *env,
                                            const struct btf_type *struct_type,
                                            const struct btf_member *member,
                                            const struct btf_type *member_type)
 {
         const struct btf_type *resolved_type;
         u32 resolved_type_id = member->type;
         struct btf_member resolved_member;
         struct btf *btf = env->btf;
 
         resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
         if (!resolved_type) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Invalid member");
                 return -EINVAL;
         }
 
         resolved_member = *member;
         resolved_member.type = resolved_type_id;
 
         return btf_type_ops(resolved_type)->check_kflag_member(env, struct_type,
                                                                &resolved_member,
                                                                resolved_type);
 }
 
 static int btf_ptr_check_member(struct btf_verifier_env *env,
                                 const struct btf_type *struct_type,
                                 const struct btf_member *member,
                                 const struct btf_type *member_type)
 {
         u32 struct_size, struct_bits_off, bytes_offset;
 
         struct_size = struct_type->size;
         struct_bits_off = member->offset;
         bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
 
         if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member is not byte aligned");
                 return -EINVAL;
         }
 
         if (struct_size - bytes_offset < sizeof(void *)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static int btf_ref_type_check_meta(struct btf_verifier_env *env,
                                    const struct btf_type *t,
                                    u32 meta_left)
 {
         const char *value;
 
         if (btf_type_vlen(t)) {
                 btf_verifier_log_type(env, t, "vlen != 0");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         if (!BTF_TYPE_ID_VALID(t->type)) {
                 btf_verifier_log_type(env, t, "Invalid type_id");
                 return -EINVAL;
         }
 
         /* typedef/type_tag type must have a valid name, and other ref types,
          * volatile, const, restrict, should have a null name.
          */
         if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
                 if (!t->name_off ||
                     !btf_name_valid_identifier(env->btf, t->name_off)) {
                         btf_verifier_log_type(env, t, "Invalid name");
                         return -EINVAL;
                 }
         } else if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG) {
                 value = btf_name_by_offset(env->btf, t->name_off);
                 if (!value || !value[0]) {
                         btf_verifier_log_type(env, t, "Invalid name");
                         return -EINVAL;
                 }
         } else {
                 if (t->name_off) {
                         btf_verifier_log_type(env, t, "Invalid name");
                         return -EINVAL;
                 }
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return 0;
 }
 
 static int btf_modifier_resolve(struct btf_verifier_env *env,
                                 const struct resolve_vertex *v)
 {
         const struct btf_type *t = v->t;
         const struct btf_type *next_type;
         u32 next_type_id = t->type;
         struct btf *btf = env->btf;
 
         next_type = btf_type_by_id(btf, next_type_id);
         if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                 btf_verifier_log_type(env, v->t, "Invalid type_id");
                 return -EINVAL;
         }
 
         if (!env_type_is_resolve_sink(env, next_type) &&
             !env_type_is_resolved(env, next_type_id))
                 return env_stack_push(env, next_type, next_type_id);
 
         /* Figure out the resolved next_type_id with size.
          * They will be stored in the current modifier's
          * resolved_ids and resolved_sizes such that it can
          * save us a few type-following when we use it later (e.g. in
          * pretty print).
          */
         if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                 if (env_type_is_resolved(env, next_type_id))
                         next_type = btf_type_id_resolve(btf, &next_type_id);
 
                 /* "typedef void new_void", "const void"...etc */
                 if (!btf_type_is_void(next_type) &&
                     !btf_type_is_fwd(next_type) &&
                     !btf_type_is_func_proto(next_type)) {
                         btf_verifier_log_type(env, v->t, "Invalid type_id");
                         return -EINVAL;
                 }
         }
 
         env_stack_pop_resolved(env, next_type_id, 0);
 
         return 0;
 }
 
 static int btf_var_resolve(struct btf_verifier_env *env,
                            const struct resolve_vertex *v)
 {
         const struct btf_type *next_type;
         const struct btf_type *t = v->t;
         u32 next_type_id = t->type;
         struct btf *btf = env->btf;
 
         next_type = btf_type_by_id(btf, next_type_id);
         if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                 btf_verifier_log_type(env, v->t, "Invalid type_id");
                 return -EINVAL;
         }
 
         if (!env_type_is_resolve_sink(env, next_type) &&
             !env_type_is_resolved(env, next_type_id))
                 return env_stack_push(env, next_type, next_type_id);
 
         if (btf_type_is_modifier(next_type)) {
                 const struct btf_type *resolved_type;
                 u32 resolved_type_id;
 
                 resolved_type_id = next_type_id;
                 resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
 
                 if (btf_type_is_ptr(resolved_type) &&
                     !env_type_is_resolve_sink(env, resolved_type) &&
                     !env_type_is_resolved(env, resolved_type_id))
                         return env_stack_push(env, resolved_type,
                                               resolved_type_id);
         }
 
         /* We must resolve to something concrete at this point, no
          * forward types or similar that would resolve to size of
          * zero is allowed.
          */
         if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                 btf_verifier_log_type(env, v->t, "Invalid type_id");
                 return -EINVAL;
         }
 
         env_stack_pop_resolved(env, next_type_id, 0);
 
         return 0;
 }
 
 static int btf_ptr_resolve(struct btf_verifier_env *env,
                            const struct resolve_vertex *v)
 {
         const struct btf_type *next_type;
         const struct btf_type *t = v->t;
         u32 next_type_id = t->type;
         struct btf *btf = env->btf;
 
         next_type = btf_type_by_id(btf, next_type_id);
         if (!next_type || btf_type_is_resolve_source_only(next_type)) {
                 btf_verifier_log_type(env, v->t, "Invalid type_id");
                 return -EINVAL;
         }
 
         if (!env_type_is_resolve_sink(env, next_type) &&
             !env_type_is_resolved(env, next_type_id))
                 return env_stack_push(env, next_type, next_type_id);
 
         /* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
          * the modifier may have stopped resolving when it was resolved
          * to a ptr (last-resolved-ptr).
          *
          * We now need to continue from the last-resolved-ptr to
          * ensure the last-resolved-ptr will not referring back to
          * the current ptr (t).
          */
         if (btf_type_is_modifier(next_type)) {
                 const struct btf_type *resolved_type;
                 u32 resolved_type_id;
 
                 resolved_type_id = next_type_id;
                 resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
 
                 if (btf_type_is_ptr(resolved_type) &&
                     !env_type_is_resolve_sink(env, resolved_type) &&
                     !env_type_is_resolved(env, resolved_type_id))
                         return env_stack_push(env, resolved_type,
                                               resolved_type_id);
         }
 
         if (!btf_type_id_size(btf, &next_type_id, NULL)) {
                 if (env_type_is_resolved(env, next_type_id))
                         next_type = btf_type_id_resolve(btf, &next_type_id);
 
                 if (!btf_type_is_void(next_type) &&
                     !btf_type_is_fwd(next_type) &&
                     !btf_type_is_func_proto(next_type)) {
                         btf_verifier_log_type(env, v->t, "Invalid type_id");
                         return -EINVAL;
                 }
         }
 
         env_stack_pop_resolved(env, next_type_id, 0);
 
         return 0;
 }
 
 static void btf_modifier_show(const struct btf *btf,
                               const struct btf_type *t,
                               u32 type_id, void *data,
                               u8 bits_offset, struct btf_show *show)
 {
         if (btf->resolved_ids)
                 t = btf_type_id_resolve(btf, &type_id);
         else
                 t = btf_type_skip_modifiers(btf, type_id, NULL);
 
         btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
 }
 
 static void btf_var_show(const struct btf *btf, const struct btf_type *t,
                          u32 type_id, void *data, u8 bits_offset,
                          struct btf_show *show)
 {
         t = btf_type_id_resolve(btf, &type_id);
 
         btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
 }
 
 static void btf_ptr_show(const struct btf *btf, const struct btf_type *t,
                          u32 type_id, void *data, u8 bits_offset,
                          struct btf_show *show)
 {
         void *safe_data;
 
         safe_data = btf_show_start_type(show, t, type_id, data);
         if (!safe_data)
                 return;
 
         /* It is a hashed value unless BTF_SHOW_PTR_RAW is specified */
         if (show->flags & BTF_SHOW_PTR_RAW)
                 btf_show_type_value(show, "0x%px", *(void **)safe_data);
         else
                 btf_show_type_value(show, "0x%p", *(void **)safe_data);
         btf_show_end_type(show);
 }
 
 static void btf_ref_type_log(struct btf_verifier_env *env,
                              const struct btf_type *t)
 {
         btf_verifier_log(env, "type_id=%u", t->type);
 }
 
 static struct btf_kind_operations modifier_ops = {
         .check_meta = btf_ref_type_check_meta,
         .resolve = btf_modifier_resolve,
         .check_member = btf_modifier_check_member,
         .check_kflag_member = btf_modifier_check_kflag_member,
         .log_details = btf_ref_type_log,
         .show = btf_modifier_show,
 };
 
 static struct btf_kind_operations ptr_ops = {
         .check_meta = btf_ref_type_check_meta,
         .resolve = btf_ptr_resolve,
         .check_member = btf_ptr_check_member,
         .check_kflag_member = btf_generic_check_kflag_member,
         .log_details = btf_ref_type_log,
         .show = btf_ptr_show,
 };
 
 static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
                               const struct btf_type *t,
                               u32 meta_left)
 {
         if (btf_type_vlen(t)) {
                 btf_verifier_log_type(env, t, "vlen != 0");
                 return -EINVAL;
         }
 
         if (t->type) {
                 btf_verifier_log_type(env, t, "type != 0");
                 return -EINVAL;
         }
 
         /* fwd type must have a valid name */
         if (!t->name_off ||
             !btf_name_valid_identifier(env->btf, t->name_off)) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return 0;
 }
 
 static void btf_fwd_type_log(struct btf_verifier_env *env,
                              const struct btf_type *t)
 {
         btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
 }
 
 static struct btf_kind_operations fwd_ops = {
         .check_meta = btf_fwd_check_meta,
         .resolve = btf_df_resolve,
         .check_member = btf_df_check_member,
         .check_kflag_member = btf_df_check_kflag_member,
         .log_details = btf_fwd_type_log,
         .show = btf_df_show,
 };
 
 static int btf_array_check_member(struct btf_verifier_env *env,
                                   const struct btf_type *struct_type,
                                   const struct btf_member *member,
                                   const struct btf_type *member_type)
 {
         u32 struct_bits_off = member->offset;
         u32 struct_size, bytes_offset;
         u32 array_type_id, array_size;
         struct btf *btf = env->btf;
 
         if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member is not byte aligned");
                 return -EINVAL;
         }
 
         array_type_id = member->type;
         btf_type_id_size(btf, &array_type_id, &array_size);
         struct_size = struct_type->size;
         bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
         if (struct_size - bytes_offset < array_size) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static s32 btf_array_check_meta(struct btf_verifier_env *env,
                                 const struct btf_type *t,
                                 u32 meta_left)
 {
         const struct btf_array *array = btf_type_array(t);
         u32 meta_needed = sizeof(*array);
 
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         /* array type should not have a name */
         if (t->name_off) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         if (btf_type_vlen(t)) {
                 btf_verifier_log_type(env, t, "vlen != 0");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         if (t->size) {
                 btf_verifier_log_type(env, t, "size != 0");
                 return -EINVAL;
         }
 
         /* Array elem type and index type cannot be in type void,
          * so !array->type and !array->index_type are not allowed.
          */
         if (!array->type || !BTF_TYPE_ID_VALID(array->type)) {
                 btf_verifier_log_type(env, t, "Invalid elem");
                 return -EINVAL;
         }
 
         if (!array->index_type || !BTF_TYPE_ID_VALID(array->index_type)) {
                 btf_verifier_log_type(env, t, "Invalid index");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return meta_needed;
 }
 
 static int btf_array_resolve(struct btf_verifier_env *env,
                              const struct resolve_vertex *v)
 {
         const struct btf_array *array = btf_type_array(v->t);
         const struct btf_type *elem_type, *index_type;
         u32 elem_type_id, index_type_id;
         struct btf *btf = env->btf;
         u32 elem_size;
 
         /* Check array->index_type */
         index_type_id = array->index_type;
         index_type = btf_type_by_id(btf, index_type_id);
         if (btf_type_nosize_or_null(index_type) ||
             btf_type_is_resolve_source_only(index_type)) {
                 btf_verifier_log_type(env, v->t, "Invalid index");
                 return -EINVAL;
         }
 
         if (!env_type_is_resolve_sink(env, index_type) &&
             !env_type_is_resolved(env, index_type_id))
                 return env_stack_push(env, index_type, index_type_id);
 
         index_type = btf_type_id_size(btf, &index_type_id, NULL);
         if (!index_type || !btf_type_is_int(index_type) ||
             !btf_type_int_is_regular(index_type)) {
                 btf_verifier_log_type(env, v->t, "Invalid index");
                 return -EINVAL;
         }
 
         /* Check array->type */
         elem_type_id = array->type;
         elem_type = btf_type_by_id(btf, elem_type_id);
         if (btf_type_nosize_or_null(elem_type) ||
             btf_type_is_resolve_source_only(elem_type)) {
                 btf_verifier_log_type(env, v->t,
                                       "Invalid elem");
                 return -EINVAL;
         }
 
         if (!env_type_is_resolve_sink(env, elem_type) &&
             !env_type_is_resolved(env, elem_type_id))
                 return env_stack_push(env, elem_type, elem_type_id);
 
         elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
         if (!elem_type) {
                 btf_verifier_log_type(env, v->t, "Invalid elem");
                 return -EINVAL;
         }
 
         if (btf_type_is_int(elem_type) && !btf_type_int_is_regular(elem_type)) {
                 btf_verifier_log_type(env, v->t, "Invalid array of int");
                 return -EINVAL;
         }
 
         if (array->nelems && elem_size > U32_MAX / array->nelems) {
                 btf_verifier_log_type(env, v->t,
                                       "Array size overflows U32_MAX");
                 return -EINVAL;
         }
 
         env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);
 
         return 0;
 }
 
 static void btf_array_log(struct btf_verifier_env *env,
                           const struct btf_type *t)
 {
         const struct btf_array *array = btf_type_array(t);
 
         btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
                          array->type, array->index_type, array->nelems);
 }
 
 static void __btf_array_show(const struct btf *btf, const struct btf_type *t,
                              u32 type_id, void *data, u8 bits_offset,
                              struct btf_show *show)
 {
         const struct btf_array *array = btf_type_array(t);
         const struct btf_kind_operations *elem_ops;
         const struct btf_type *elem_type;
         u32 i, elem_size = 0, elem_type_id;
         u16 encoding = 0;
 
         elem_type_id = array->type;
         elem_type = btf_type_skip_modifiers(btf, elem_type_id, NULL);
         if (elem_type && btf_type_has_size(elem_type))
                 elem_size = elem_type->size;
 
         if (elem_type && btf_type_is_int(elem_type)) {
                 u32 int_type = btf_type_int(elem_type);
 
                 encoding = BTF_INT_ENCODING(int_type);
 
                 /*
                  * BTF_INT_CHAR encoding never seems to be set for
                  * char arrays, so if size is 1 and element is
                  * printable as a char, we'll do that.
                  */
                 if (elem_size == 1)
                         encoding = BTF_INT_CHAR;
         }
 
         if (!btf_show_start_array_type(show, t, type_id, encoding, data))
                 return;
 
         if (!elem_type)
                 goto out;
         elem_ops = btf_type_ops(elem_type);
 
         for (i = 0; i < array->nelems; i++) {
 
                 btf_show_start_array_member(show);
 
                 elem_ops->show(btf, elem_type, elem_type_id, data,
                                bits_offset, show);
                 data += elem_size;
 
                 btf_show_end_array_member(show);
 
                 if (show->state.array_terminated)
                         break;
         }
 out:
         btf_show_end_array_type(show);
 }
 
 static void btf_array_show(const struct btf *btf, const struct btf_type *t,
                            u32 type_id, void *data, u8 bits_offset,
                            struct btf_show *show)
 {
         const struct btf_member *m = show->state.member;
 
         /*
          * First check if any members would be shown (are non-zero).
          * See comments above "struct btf_show" definition for more
          * details on how this works at a high-level.
          */
         if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
                 if (!show->state.depth_check) {
                         show->state.depth_check = show->state.depth + 1;
                         show->state.depth_to_show = 0;
                 }
                 __btf_array_show(btf, t, type_id, data, bits_offset, show);
                 show->state.member = m;
 
                 if (show->state.depth_check != show->state.depth + 1)
                         return;
                 show->state.depth_check = 0;
 
                 if (show->state.depth_to_show <= show->state.depth)
                         return;
                 /*
                  * Reaching here indicates we have recursed and found
                  * non-zero array member(s).
                  */
         }
         __btf_array_show(btf, t, type_id, data, bits_offset, show);
 }
 
 static struct btf_kind_operations array_ops = {
         .check_meta = btf_array_check_meta,
         .resolve = btf_array_resolve,
         .check_member = btf_array_check_member,
         .check_kflag_member = btf_generic_check_kflag_member,
         .log_details = btf_array_log,
         .show = btf_array_show,
 };
 
 static int btf_struct_check_member(struct btf_verifier_env *env,
                                    const struct btf_type *struct_type,
                                    const struct btf_member *member,
                                    const struct btf_type *member_type)
 {
         u32 struct_bits_off = member->offset;
         u32 struct_size, bytes_offset;
 
         if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member is not byte aligned");
                 return -EINVAL;
         }
 
         struct_size = struct_type->size;
         bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
         if (struct_size - bytes_offset < member_type->size) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static s32 btf_struct_check_meta(struct btf_verifier_env *env,
                                  const struct btf_type *t,
                                  u32 meta_left)
 {
         bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
         const struct btf_member *member;
         u32 meta_needed, last_offset;
         struct btf *btf = env->btf;
         u32 struct_size = t->size;
         u32 offset;
         u16 i;
 
         meta_needed = btf_type_vlen(t) * sizeof(*member);
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         /* struct type either no name or a valid one */
         if (t->name_off &&
             !btf_name_valid_identifier(env->btf, t->name_off)) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         last_offset = 0;
         for_each_member(i, t, member) {
                 if (!btf_name_offset_valid(btf, member->name_off)) {
                         btf_verifier_log_member(env, t, member,
                                                 "Invalid member name_offset:%u",
                                                 member->name_off);
                         return -EINVAL;
                 }
 
                 /* struct member either no name or a valid one */
                 if (member->name_off &&
                     !btf_name_valid_identifier(btf, member->name_off)) {
                         btf_verifier_log_member(env, t, member, "Invalid name");
                         return -EINVAL;
                 }
                 /* A member cannot be in type void */
                 if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
                         btf_verifier_log_member(env, t, member,
                                                 "Invalid type_id");
                         return -EINVAL;
                 }
 
                 offset = __btf_member_bit_offset(t, member);
                 if (is_union && offset) {
                         btf_verifier_log_member(env, t, member,
                                                 "Invalid member bits_offset");
                         return -EINVAL;
                 }
 
                 /*
                  * ">" instead of ">=" because the last member could be
                  * "char a[0];"
                  */
                 if (last_offset > offset) {
                         btf_verifier_log_member(env, t, member,
                                                 "Invalid member bits_offset");
                         return -EINVAL;
                 }
 
                 if (BITS_ROUNDUP_BYTES(offset) > struct_size) {
                         btf_verifier_log_member(env, t, member,
                                                 "Member bits_offset exceeds its struct size");
                         return -EINVAL;
                 }
 
                 btf_verifier_log_member(env, t, member, NULL);
                 last_offset = offset;
         }
 
         return meta_needed;
 }
 
 static int btf_struct_resolve(struct btf_verifier_env *env,
                               const struct resolve_vertex *v)
 {
         const struct btf_member *member;
         int err;
         u16 i;
 
         /* Before continue resolving the next_member,
          * ensure the last member is indeed resolved to a
          * type with size info.
          */
         if (v->next_member) {
                 const struct btf_type *last_member_type;
                 const struct btf_member *last_member;
                 u32 last_member_type_id;
 
                 last_member = btf_type_member(v->t) + v->next_member - 1;
                 last_member_type_id = last_member->type;
                 if (WARN_ON_ONCE(!env_type_is_resolved(env,
                                                        last_member_type_id)))
                         return -EINVAL;
 
                 last_member_type = btf_type_by_id(env->btf,
                                                   last_member_type_id);
                 if (btf_type_kflag(v->t))
                         err = btf_type_ops(last_member_type)->check_kflag_member(env, v->t,
                                                                 last_member,
                                                                 last_member_type);
                 else
                         err = btf_type_ops(last_member_type)->check_member(env, v->t,
                                                                 last_member,
                                                                 last_member_type);
                 if (err)
                         return err;
         }
 
         for_each_member_from(i, v->next_member, v->t, member) {
                 u32 member_type_id = member->type;
                 const struct btf_type *member_type = btf_type_by_id(env->btf,
                                                                 member_type_id);
 
                 if (btf_type_nosize_or_null(member_type) ||
                     btf_type_is_resolve_source_only(member_type)) {
                         btf_verifier_log_member(env, v->t, member,
                                                 "Invalid member");
                         return -EINVAL;
                 }
 
                 if (!env_type_is_resolve_sink(env, member_type) &&
                     !env_type_is_resolved(env, member_type_id)) {
                         env_stack_set_next_member(env, i + 1);
                         return env_stack_push(env, member_type, member_type_id);
                 }
 
                 if (btf_type_kflag(v->t))
                         err = btf_type_ops(member_type)->check_kflag_member(env, v->t,
                                                                             member,
                                                                             member_type);
                 else
                         err = btf_type_ops(member_type)->check_member(env, v->t,
                                                                       member,
                                                                       member_type);
                 if (err)
                         return err;
         }
 
         env_stack_pop_resolved(env, 0, 0);
 
         return 0;
 }
 
 static void btf_struct_log(struct btf_verifier_env *env,
                            const struct btf_type *t)
 {
         btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
 }
 
 enum {
         BTF_FIELD_IGNORE = 0,
         BTF_FIELD_FOUND  = 1,
 };
 
 struct btf_field_info {
         enum btf_field_type type;
         u32 off;
         union {
                 struct {
                         u32 type_id;
                 } kptr;
                 struct {
                         const char *node_name;
                         u32 value_btf_id;
                 } graph_root;
         };
 };
 
 static int btf_find_struct(const struct btf *btf, const struct btf_type *t,
                            u32 off, int sz, enum btf_field_type field_type,
                            struct btf_field_info *info)
 {
         if (!__btf_type_is_struct(t))
                 return BTF_FIELD_IGNORE;
         if (t->size != sz)
                 return BTF_FIELD_IGNORE;
         info->type = field_type;
         info->off = off;
         return BTF_FIELD_FOUND;
 }
 
 static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
                          u32 off, int sz, struct btf_field_info *info)
 {
         enum btf_field_type type;
         u32 res_id;
 
         /* Permit modifiers on the pointer itself */
         if (btf_type_is_volatile(t))
                 t = btf_type_by_id(btf, t->type);
         /* For PTR, sz is always == 8 */
         if (!btf_type_is_ptr(t))
                 return BTF_FIELD_IGNORE;
         t = btf_type_by_id(btf, t->type);
 
         if (!btf_type_is_type_tag(t))
                 return BTF_FIELD_IGNORE;
         /* Reject extra tags */
         if (btf_type_is_type_tag(btf_type_by_id(btf, t->type)))
                 return -EINVAL;
         if (!strcmp("kptr_untrusted", __btf_name_by_offset(btf, t->name_off)))
                 type = BPF_KPTR_UNREF;
         else if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off)))
                 type = BPF_KPTR_REF;
         else if (!strcmp("percpu_kptr", __btf_name_by_offset(btf, t->name_off)))
                 type = BPF_KPTR_PERCPU;
         else
                 return -EINVAL;
 
         /* Get the base type */
         t = btf_type_skip_modifiers(btf, t->type, &res_id);
         /* Only pointer to struct is allowed */
         if (!__btf_type_is_struct(t))
                 return -EINVAL;
 
         info->type = type;
         info->off = off;
         info->kptr.type_id = res_id;
         return BTF_FIELD_FOUND;
 }
 
 int btf_find_next_decl_tag(const struct btf *btf, const struct btf_type *pt,
                            int comp_idx, const char *tag_key, int last_id)
 {
         int len = strlen(tag_key);
         int i, n;
 
         for (i = last_id + 1, n = btf_nr_types(btf); i < n; i++) {
                 const struct btf_type *t = btf_type_by_id(btf, i);
 
                 if (!btf_type_is_decl_tag(t))
                         continue;
                 if (pt != btf_type_by_id(btf, t->type))
                         continue;
                 if (btf_type_decl_tag(t)->component_idx != comp_idx)
                         continue;
                 if (strncmp(__btf_name_by_offset(btf, t->name_off), tag_key, len))
                         continue;
                 return i;
         }
         return -ENOENT;
 }
 
 const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type *pt,
                                     int comp_idx, const char *tag_key)
 {
         const char *value = NULL;
         const struct btf_type *t;
         int len, id;
 
         id = btf_find_next_decl_tag(btf, pt, comp_idx, tag_key, 0);
         if (id < 0)
                 return ERR_PTR(id);
 
         t = btf_type_by_id(btf, id);
         len = strlen(tag_key);
         value = __btf_name_by_offset(btf, t->name_off) + len;
 
         /* Prevent duplicate entries for same type */
         id = btf_find_next_decl_tag(btf, pt, comp_idx, tag_key, id);
         if (id >= 0)
                 return ERR_PTR(-EEXIST);
 
         return value;
 }
 
 static int
 btf_find_graph_root(const struct btf *btf, const struct btf_type *pt,
                     const struct btf_type *t, int comp_idx, u32 off,
                     int sz, struct btf_field_info *info,
                     enum btf_field_type head_type)
 {
         const char *node_field_name;
         const char *value_type;
         s32 id;
 
         if (!__btf_type_is_struct(t))
                 return BTF_FIELD_IGNORE;
         if (t->size != sz)
                 return BTF_FIELD_IGNORE;
         value_type = btf_find_decl_tag_value(btf, pt, comp_idx, "contains:");
         if (IS_ERR(value_type))
                 return -EINVAL;
         node_field_name = strstr(value_type, ":");
         if (!node_field_name)
                 return -EINVAL;
         value_type = kstrndup(value_type, node_field_name - value_type, GFP_KERNEL | __GFP_NOWARN);
         if (!value_type)
                 return -ENOMEM;
         id = btf_find_by_name_kind(btf, value_type, BTF_KIND_STRUCT);
         kfree(value_type);
         if (id < 0)
                 return id;
         node_field_name++;
         if (str_is_empty(node_field_name))
                 return -EINVAL;
         info->type = head_type;
         info->off = off;
         info->graph_root.value_btf_id = id;
         info->graph_root.node_name = node_field_name;
         return BTF_FIELD_FOUND;
 }
 
 #define field_mask_test_name(field_type, field_type_str) \
         if (field_mask & field_type && !strcmp(name, field_type_str)) { \
                 type = field_type;                                      \
                 goto end;                                               \
         }
 
 static int btf_get_field_type(const struct btf *btf, const struct btf_type *var_type,
                               u32 field_mask, u32 *seen_mask,
                               int *align, int *sz)
 {
         int type = 0;
         const char *name = __btf_name_by_offset(btf, var_type->name_off);
 
         if (field_mask & BPF_SPIN_LOCK) {
                 if (!strcmp(name, "bpf_spin_lock")) {
                         if (*seen_mask & BPF_SPIN_LOCK)
                                 return -E2BIG;
                         *seen_mask |= BPF_SPIN_LOCK;
                         type = BPF_SPIN_LOCK;
                         goto end;
                 }
         }
         if (field_mask & BPF_TIMER) {
                 if (!strcmp(name, "bpf_timer")) {
                         if (*seen_mask & BPF_TIMER)
                                 return -E2BIG;
                         *seen_mask |= BPF_TIMER;
                         type = BPF_TIMER;
                         goto end;
                 }
         }
         if (field_mask & BPF_WORKQUEUE) {
                 if (!strcmp(name, "bpf_wq")) {
                         if (*seen_mask & BPF_WORKQUEUE)
                                 return -E2BIG;
                         *seen_mask |= BPF_WORKQUEUE;
                         type = BPF_WORKQUEUE;
                         goto end;
                 }
         }
         field_mask_test_name(BPF_LIST_HEAD, "bpf_list_head");
         field_mask_test_name(BPF_LIST_NODE, "bpf_list_node");
         field_mask_test_name(BPF_RB_ROOT,   "bpf_rb_root");
         field_mask_test_name(BPF_RB_NODE,   "bpf_rb_node");
         field_mask_test_name(BPF_REFCOUNT,  "bpf_refcount");
 
         /* Only return BPF_KPTR when all other types with matchable names fail */
         if (field_mask & BPF_KPTR && !__btf_type_is_struct(var_type)) {
                 type = BPF_KPTR_REF;
                 goto end;
         }
         return 0;
 end:
         *sz = btf_field_type_size(type);
         *align = btf_field_type_align(type);
         return type;
 }
 
 #undef field_mask_test_name
 
 /* Repeat a number of fields for a specified number of times.
  *
  * Copy the fields starting from the first field and repeat them for
  * repeat_cnt times. The fields are repeated by adding the offset of each
  * field with
  *   (i + 1) * elem_size
  * where i is the repeat index and elem_size is the size of an element.
  */
 static int btf_repeat_fields(struct btf_field_info *info,
                              u32 field_cnt, u32 repeat_cnt, u32 elem_size)
 {
         u32 i, j;
         u32 cur;
 
         /* Ensure not repeating fields that should not be repeated. */
         for (i = 0; i < field_cnt; i++) {
                 switch (info[i].type) {
                 case BPF_KPTR_UNREF:
                 case BPF_KPTR_REF:
                 case BPF_KPTR_PERCPU:
                 case BPF_LIST_HEAD:
                 case BPF_RB_ROOT:
                         break;
                 default:
                         return -EINVAL;
                 }
         }
 
         cur = field_cnt;
         for (i = 0; i < repeat_cnt; i++) {
                 memcpy(&info[cur], &info[0], field_cnt * sizeof(info[0]));
                 for (j = 0; j < field_cnt; j++)
                         info[cur++].off += (i + 1) * elem_size;
         }
 
         return 0;
 }
 
 static int btf_find_struct_field(const struct btf *btf,
                                  const struct btf_type *t, u32 field_mask,
                                  struct btf_field_info *info, int info_cnt,
                                  u32 level);
 
 /* Find special fields in the struct type of a field.
  *
  * This function is used to find fields of special types that is not a
  * global variable or a direct field of a struct type. It also handles the
  * repetition if it is the element type of an array.
  */
 static int btf_find_nested_struct(const struct btf *btf, const struct btf_type *t,
                                   u32 off, u32 nelems,
                                   u32 field_mask, struct btf_field_info *info,
                                   int info_cnt, u32 level)
 {
         int ret, err, i;
 
         level++;
         if (level >= MAX_RESOLVE_DEPTH)
                 return -E2BIG;
 
         ret = btf_find_struct_field(btf, t, field_mask, info, info_cnt, level);
 
         if (ret <= 0)
                 return ret;
 
         /* Shift the offsets of the nested struct fields to the offsets
          * related to the container.
          */
         for (i = 0; i < ret; i++)
                 info[i].off += off;
 
         if (nelems > 1) {
                 err = btf_repeat_fields(info, ret, nelems - 1, t->size);
                 if (err == 0)
                         ret *= nelems;
                 else
                         ret = err;
         }
 
         return ret;
 }
 
 static int btf_find_field_one(const struct btf *btf,
                               const struct btf_type *var,
                               const struct btf_type *var_type,
                               int var_idx,
                               u32 off, u32 expected_size,
                               u32 field_mask, u32 *seen_mask,
                               struct btf_field_info *info, int info_cnt,
                               u32 level)
 {
         int ret, align, sz, field_type;
         struct btf_field_info tmp;
         const struct btf_array *array;
         u32 i, nelems = 1;
 
         /* Walk into array types to find the element type and the number of
          * elements in the (flattened) array.
          */
         for (i = 0; i < MAX_RESOLVE_DEPTH && btf_type_is_array(var_type); i++) {
                 array = btf_array(var_type);
                 nelems *= array->nelems;
                 var_type = btf_type_by_id(btf, array->type);
         }
         if (i == MAX_RESOLVE_DEPTH)
                 return -E2BIG;
         if (nelems == 0)
                 return 0;
 
         field_type = btf_get_field_type(btf, var_type,
                                         field_mask, seen_mask, &align, &sz);
         /* Look into variables of struct types */
         if (!field_type && __btf_type_is_struct(var_type)) {
                 sz = var_type->size;
                 if (expected_size && expected_size != sz * nelems)
                         return 0;
                 ret = btf_find_nested_struct(btf, var_type, off, nelems, field_mask,
                                              &info[0], info_cnt, level);
                 return ret;
         }
 
         if (field_type == 0)
                 return 0;
         if (field_type < 0)
                 return field_type;
 
         if (expected_size && expected_size != sz * nelems)
                 return 0;
         if (off % align)
                 return 0;
 
         switch (field_type) {
         case BPF_SPIN_LOCK:
         case BPF_TIMER:
         case BPF_WORKQUEUE:
         case BPF_LIST_NODE:
         case BPF_RB_NODE:
         case BPF_REFCOUNT:
                 ret = btf_find_struct(btf, var_type, off, sz, field_type,
                                       info_cnt ? &info[0] : &tmp);
                 if (ret < 0)
                         return ret;
                 break;
         case BPF_KPTR_UNREF:
         case BPF_KPTR_REF:
         case BPF_KPTR_PERCPU:
                 ret = btf_find_kptr(btf, var_type, off, sz,
                                     info_cnt ? &info[0] : &tmp);
                 if (ret < 0)
                         return ret;
                 break;
         case BPF_LIST_HEAD:
         case BPF_RB_ROOT:
                 ret = btf_find_graph_root(btf, var, var_type,
                                           var_idx, off, sz,
                                           info_cnt ? &info[0] : &tmp,
                                           field_type);
                 if (ret < 0)
                         return ret;
                 break;
         default:
                 return -EFAULT;
         }
 
         if (ret == BTF_FIELD_IGNORE)
                 return 0;
         if (nelems > info_cnt)
                 return -E2BIG;
         if (nelems > 1) {
                 ret = btf_repeat_fields(info, 1, nelems - 1, sz);
                 if (ret < 0)
                         return ret;
         }
         return nelems;
 }
 
 static int btf_find_struct_field(const struct btf *btf,
                                  const struct btf_type *t, u32 field_mask,
                                  struct btf_field_info *info, int info_cnt,
                                  u32 level)
 {
         int ret, idx = 0;
         const struct btf_member *member;
         u32 i, off, seen_mask = 0;
 
         for_each_member(i, t, member) {
                 const struct btf_type *member_type = btf_type_by_id(btf,
                                                                     member->type);
 
                 off = __btf_member_bit_offset(t, member);
                 if (off % 8)
                         /* valid C code cannot generate such BTF */
                         return -EINVAL;
                 off /= 8;
 
                 ret = btf_find_field_one(btf, t, member_type, i,
                                          off, 0,
                                          field_mask, &seen_mask,
                                          &info[idx], info_cnt - idx, level);
                 if (ret < 0)
                         return ret;
                 idx += ret;
         }
         return idx;
 }
 
 static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
                                 u32 field_mask, struct btf_field_info *info,
                                 int info_cnt, u32 level)
 {
         int ret, idx = 0;
         const struct btf_var_secinfo *vsi;
         u32 i, off, seen_mask = 0;
 
         for_each_vsi(i, t, vsi) {
                 const struct btf_type *var = btf_type_by_id(btf, vsi->type);
                 const struct btf_type *var_type = btf_type_by_id(btf, var->type);
 
                 off = vsi->offset;
                 ret = btf_find_field_one(btf, var, var_type, -1, off, vsi->size,
                                          field_mask, &seen_mask,
                                          &info[idx], info_cnt - idx,
                                          level);
                 if (ret < 0)
                         return ret;
                 idx += ret;
         }
         return idx;
 }
 
 static int btf_find_field(const struct btf *btf, const struct btf_type *t,
                           u32 field_mask, struct btf_field_info *info,
                           int info_cnt)
 {
         if (__btf_type_is_struct(t))
                 return btf_find_struct_field(btf, t, field_mask, info, info_cnt, 0);
         else if (btf_type_is_datasec(t))
                 return btf_find_datasec_var(btf, t, field_mask, info, info_cnt, 0);
         return -EINVAL;
 }
 
 static int btf_parse_kptr(const struct btf *btf, struct btf_field *field,
                           struct btf_field_info *info)
 {
         struct module *mod = NULL;
         const struct btf_type *t;
         /* If a matching btf type is found in kernel or module BTFs, kptr_ref
          * is that BTF, otherwise it's program BTF
          */
         struct btf *kptr_btf;
         int ret;
         s32 id;
 
         /* Find type in map BTF, and use it to look up the matching type
          * in vmlinux or module BTFs, by name and kind.
          */
         t = btf_type_by_id(btf, info->kptr.type_id);
         id = bpf_find_btf_id(__btf_name_by_offset(btf, t->name_off), BTF_INFO_KIND(t->info),
                              &kptr_btf);
         if (id == -ENOENT) {
                 /* btf_parse_kptr should only be called w/ btf = program BTF */
                 WARN_ON_ONCE(btf_is_kernel(btf));
 
                 /* Type exists only in program BTF. Assume that it's a MEM_ALLOC
                  * kptr allocated via bpf_obj_new
                  */
                 field->kptr.dtor = NULL;
                 id = info->kptr.type_id;
                 kptr_btf = (struct btf *)btf;
                 btf_get(kptr_btf);
                 goto found_dtor;
         }
         if (id < 0)
                 return id;
 
         /* Find and stash the function pointer for the destruction function that
          * needs to be eventually invoked from the map free path.
          */
         if (info->type == BPF_KPTR_REF) {
                 const struct btf_type *dtor_func;
                 const char *dtor_func_name;
                 unsigned long addr;
                 s32 dtor_btf_id;
 
                 /* This call also serves as a whitelist of allowed objects that
                  * can be used as a referenced pointer and be stored in a map at
                  * the same time.
                  */
                 dtor_btf_id = btf_find_dtor_kfunc(kptr_btf, id);
                 if (dtor_btf_id < 0) {
                         ret = dtor_btf_id;
                         goto end_btf;
                 }
 
                 dtor_func = btf_type_by_id(kptr_btf, dtor_btf_id);
                 if (!dtor_func) {
                         ret = -ENOENT;
                         goto end_btf;
                 }
 
                 if (btf_is_module(kptr_btf)) {
                         mod = btf_try_get_module(kptr_btf);
                         if (!mod) {
                                 ret = -ENXIO;
                                 goto end_btf;
                         }
                 }
 
                 /* We already verified dtor_func to be btf_type_is_func
                  * in register_btf_id_dtor_kfuncs.
                  */
                 dtor_func_name = __btf_name_by_offset(kptr_btf, dtor_func->name_off);
                 addr = kallsyms_lookup_name(dtor_func_name);
                 if (!addr) {
                         ret = -EINVAL;
                         goto end_mod;
                 }
                 field->kptr.dtor = (void *)addr;
         }
 
 found_dtor:
         field->kptr.btf_id = id;
         field->kptr.btf = kptr_btf;
         field->kptr.module = mod;
         return 0;
 end_mod:
         module_put(mod);
 end_btf:
         btf_put(kptr_btf);
         return ret;
 }
 
 static int btf_parse_graph_root(const struct btf *btf,
                                 struct btf_field *field,
                                 struct btf_field_info *info,
                                 const char *node_type_name,
                                 size_t node_type_align)
 {
         const struct btf_type *t, *n = NULL;
         const struct btf_member *member;
         u32 offset;
         int i;
 
         t = btf_type_by_id(btf, info->graph_root.value_btf_id);
         /* We've already checked that value_btf_id is a struct type. We
          * just need to figure out the offset of the list_node, and
          * verify its type.
          */
         for_each_member(i, t, member) {
                 if (strcmp(info->graph_root.node_name,
                            __btf_name_by_offset(btf, member->name_off)))
                         continue;
                 /* Invalid BTF, two members with same name */
                 if (n)
                         return -EINVAL;
                 n = btf_type_by_id(btf, member->type);
                 if (!__btf_type_is_struct(n))
                         return -EINVAL;
                 if (strcmp(node_type_name, __btf_name_by_offset(btf, n->name_off)))
                         return -EINVAL;
                 offset = __btf_member_bit_offset(n, member);
                 if (offset % 8)
                         return -EINVAL;
                 offset /= 8;
                 if (offset % node_type_align)
                         return -EINVAL;
 
                 field->graph_root.btf = (struct btf *)btf;
                 field->graph_root.value_btf_id = info->graph_root.value_btf_id;
                 field->graph_root.node_offset = offset;
         }
         if (!n)
                 return -ENOENT;
         return 0;
 }
 
 static int btf_parse_list_head(const struct btf *btf, struct btf_field *field,
                                struct btf_field_info *info)
 {
         return btf_parse_graph_root(btf, field, info, "bpf_list_node",
                                             __alignof__(struct bpf_list_node));
 }
 
 static int btf_parse_rb_root(const struct btf *btf, struct btf_field *field,
                              struct btf_field_info *info)
 {
         return btf_parse_graph_root(btf, field, info, "bpf_rb_node",
                                             __alignof__(struct bpf_rb_node));
 }
 
 static int btf_field_cmp(const void *_a, const void *_b, const void *priv)
 {
         const struct btf_field *a = (const struct btf_field *)_a;
         const struct btf_field *b = (const struct btf_field *)_b;
 
         if (a->offset < b->offset)
                 return -1;
         else if (a->offset > b->offset)
                 return 1;
         return 0;
 }
 
 struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t,
                                     u32 field_mask, u32 value_size)
 {
         struct btf_field_info info_arr[BTF_FIELDS_MAX];
         u32 next_off = 0, field_type_size;
         struct btf_record *rec;
         int ret, i, cnt;
 
         ret = btf_find_field(btf, t, field_mask, info_arr, ARRAY_SIZE(info_arr));
         if (ret < 0)
                 return ERR_PTR(ret);
         if (!ret)
                 return NULL;
 
         cnt = ret;
         /* This needs to be kzalloc to zero out padding and unused fields, see
          * comment in btf_record_equal.
          */
         rec = kzalloc(offsetof(struct btf_record, fields[cnt]), GFP_KERNEL | __GFP_NOWARN);
         if (!rec)
                 return ERR_PTR(-ENOMEM);
 
         rec->spin_lock_off = -EINVAL;
         rec->timer_off = -EINVAL;
         rec->wq_off = -EINVAL;
         rec->refcount_off = -EINVAL;
         for (i = 0; i < cnt; i++) {
                 field_type_size = btf_field_type_size(info_arr[i].type);
                 if (info_arr[i].off + field_type_size > value_size) {
                         WARN_ONCE(1, "verifier bug off %d size %d", info_arr[i].off, value_size);
                         ret = -EFAULT;
                         goto end;
                 }
                 if (info_arr[i].off < next_off) {
                         ret = -EEXIST;
                         goto end;
                 }
                 next_off = info_arr[i].off + field_type_size;
 
                 rec->field_mask |= info_arr[i].type;
                 rec->fields[i].offset = info_arr[i].off;
                 rec->fields[i].type = info_arr[i].type;
                 rec->fields[i].size = field_type_size;
 
                 switch (info_arr[i].type) {
                 case BPF_SPIN_LOCK:
                         WARN_ON_ONCE(rec->spin_lock_off >= 0);
                         /* Cache offset for faster lookup at runtime */
                         rec->spin_lock_off = rec->fields[i].offset;
                         break;
                 case BPF_TIMER:
                         WARN_ON_ONCE(rec->timer_off >= 0);
                         /* Cache offset for faster lookup at runtime */
                         rec->timer_off = rec->fields[i].offset;
                         break;
                 case BPF_WORKQUEUE:
                         WARN_ON_ONCE(rec->wq_off >= 0);
                         /* Cache offset for faster lookup at runtime */
                         rec->wq_off = rec->fields[i].offset;
                         break;
                 case BPF_REFCOUNT:
                         WARN_ON_ONCE(rec->refcount_off >= 0);
                         /* Cache offset for faster lookup at runtime */
                         rec->refcount_off = rec->fields[i].offset;
                         break;
                 case BPF_KPTR_UNREF:
                 case BPF_KPTR_REF:
                 case BPF_KPTR_PERCPU:
                         ret = btf_parse_kptr(btf, &rec->fields[i], &info_arr[i]);
                         if (ret < 0)
                                 goto end;
                         break;
                 case BPF_LIST_HEAD:
                         ret = btf_parse_list_head(btf, &rec->fields[i], &info_arr[i]);
                         if (ret < 0)
                                 goto end;
                         break;
                 case BPF_RB_ROOT:
                         ret = btf_parse_rb_root(btf, &rec->fields[i], &info_arr[i]);
                         if (ret < 0)
                                 goto end;
                         break;
                 case BPF_LIST_NODE:
                 case BPF_RB_NODE:
                         break;
                 default:
                         ret = -EFAULT;
                         goto end;
                 }
                 rec->cnt++;
         }
 
         /* bpf_{list_head, rb_node} require bpf_spin_lock */
         if ((btf_record_has_field(rec, BPF_LIST_HEAD) ||
              btf_record_has_field(rec, BPF_RB_ROOT)) && rec->spin_lock_off < 0) {
                 ret = -EINVAL;
                 goto end;
         }
 
         if (rec->refcount_off < 0 &&
             btf_record_has_field(rec, BPF_LIST_NODE) &&
             btf_record_has_field(rec, BPF_RB_NODE)) {
                 ret = -EINVAL;
                 goto end;
         }
 
         sort_r(rec->fields, rec->cnt, sizeof(struct btf_field), btf_field_cmp,
                NULL, rec);
 
         return rec;
 end:
         btf_record_free(rec);
         return ERR_PTR(ret);
 }
 
 int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec)
 {
         int i;
 
         /* There are three types that signify ownership of some other type:
          *  kptr_ref, bpf_list_head, bpf_rb_root.
          * kptr_ref only supports storing kernel types, which can't store
          * references to program allocated local types.
          *
          * Hence we only need to ensure that bpf_{list_head,rb_root} ownership
          * does not form cycles.
          */
         if (IS_ERR_OR_NULL(rec) || !(rec->field_mask & BPF_GRAPH_ROOT))
                 return 0;
         for (i = 0; i < rec->cnt; i++) {
                 struct btf_struct_meta *meta;
                 u32 btf_id;
 
                 if (!(rec->fields[i].type & BPF_GRAPH_ROOT))
                         continue;
                 btf_id = rec->fields[i].graph_root.value_btf_id;
                 meta = btf_find_struct_meta(btf, btf_id);
                 if (!meta)
                         return -EFAULT;
                 rec->fields[i].graph_root.value_rec = meta->record;
 
                 /* We need to set value_rec for all root types, but no need
                  * to check ownership cycle for a type unless it's also a
                  * node type.
                  */
                 if (!(rec->field_mask & BPF_GRAPH_NODE))
                         continue;
 
                 /* We need to ensure ownership acyclicity among all types. The
                  * proper way to do it would be to topologically sort all BTF
                  * IDs based on the ownership edges, since there can be multiple
                  * bpf_{list_head,rb_node} in a type. Instead, we use the
                  * following resaoning:
                  *
                  * - A type can only be owned by another type in user BTF if it
                  *   has a bpf_{list,rb}_node. Let's call these node types.
                  * - A type can only _own_ another type in user BTF if it has a
                  *   bpf_{list_head,rb_root}. Let's call these root types.
                  *
                  * We ensure that if a type is both a root and node, its
                  * element types cannot be root types.
                  *
                  * To ensure acyclicity:
                  *
                  * When A is an root type but not a node, its ownership
                  * chain can be:
                  *      A -> B -> C
                  * Where:
                  * - A is an root, e.g. has bpf_rb_root.
                  * - B is both a root and node, e.g. has bpf_rb_node and
                  *   bpf_list_head.
                  * - C is only an root, e.g. has bpf_list_node
                  *
                  * When A is both a root and node, some other type already
                  * owns it in the BTF domain, hence it can not own
                  * another root type through any of the ownership edges.
                  *      A -> B
                  * Where:
                  * - A is both an root and node.
                  * - B is only an node.
                  */
                 if (meta->record->field_mask & BPF_GRAPH_ROOT)
                         return -ELOOP;
         }
         return 0;
 }
 
 static void __btf_struct_show(const struct btf *btf, const struct btf_type *t,
                               u32 type_id, void *data, u8 bits_offset,
                               struct btf_show *show)
 {
         const struct btf_member *member;
         void *safe_data;
         u32 i;
 
         safe_data = btf_show_start_struct_type(show, t, type_id, data);
         if (!safe_data)
                 return;
 
         for_each_member(i, t, member) {
                 const struct btf_type *member_type = btf_type_by_id(btf,
                                                                 member->type);
                 const struct btf_kind_operations *ops;
                 u32 member_offset, bitfield_size;
                 u32 bytes_offset;
                 u8 bits8_offset;
 
                 btf_show_start_member(show, member);
 
                 member_offset = __btf_member_bit_offset(t, member);
                 bitfield_size = __btf_member_bitfield_size(t, member);
                 bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
                 bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
                 if (bitfield_size) {
                         safe_data = btf_show_start_type(show, member_type,
                                                         member->type,
                                                         data + bytes_offset);
                         if (safe_data)
                                 btf_bitfield_show(safe_data,
                                                   bits8_offset,
                                                   bitfield_size, show);
                         btf_show_end_type(show);
                 } else {
                         ops = btf_type_ops(member_type);
                         ops->show(btf, member_type, member->type,
                                   data + bytes_offset, bits8_offset, show);
                 }
 
                 btf_show_end_member(show);
         }
 
         btf_show_end_struct_type(show);
 }
 
 static void btf_struct_show(const struct btf *btf, const struct btf_type *t,
                             u32 type_id, void *data, u8 bits_offset,
                             struct btf_show *show)
 {
         const struct btf_member *m = show->state.member;
 
         /*
          * First check if any members would be shown (are non-zero).
          * See comments above "struct btf_show" definition for more
          * details on how this works at a high-level.
          */
         if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
                 if (!show->state.depth_check) {
                         show->state.depth_check = show->state.depth + 1;
                         show->state.depth_to_show = 0;
                 }
                 __btf_struct_show(btf, t, type_id, data, bits_offset, show);
                 /* Restore saved member data here */
                 show->state.member = m;
                 if (show->state.depth_check != show->state.depth + 1)
                         return;
                 show->state.depth_check = 0;
 
                 if (show->state.depth_to_show <= show->state.depth)
                         return;
                 /*
                  * Reaching here indicates we have recursed and found
                  * non-zero child values.
                  */
         }
 
         __btf_struct_show(btf, t, type_id, data, bits_offset, show);
 }
 
 static struct btf_kind_operations struct_ops = {
         .check_meta = btf_struct_check_meta,
         .resolve = btf_struct_resolve,
         .check_member = btf_struct_check_member,
         .check_kflag_member = btf_generic_check_kflag_member,
         .log_details = btf_struct_log,
         .show = btf_struct_show,
 };
 
 static int btf_enum_check_member(struct btf_verifier_env *env,
                                  const struct btf_type *struct_type,
                                  const struct btf_member *member,
                                  const struct btf_type *member_type)
 {
         u32 struct_bits_off = member->offset;
         u32 struct_size, bytes_offset;
 
         if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member is not byte aligned");
                 return -EINVAL;
         }
 
         struct_size = struct_type->size;
         bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
         if (struct_size - bytes_offset < member_type->size) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static int btf_enum_check_kflag_member(struct btf_verifier_env *env,
                                        const struct btf_type *struct_type,
                                        const struct btf_member *member,
                                        const struct btf_type *member_type)
 {
         u32 struct_bits_off, nr_bits, bytes_end, struct_size;
         u32 int_bitsize = sizeof(int) * BITS_PER_BYTE;
 
         struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
         nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
         if (!nr_bits) {
                 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
                         btf_verifier_log_member(env, struct_type, member,
                                                 "Member is not byte aligned");
                         return -EINVAL;
                 }
 
                 nr_bits = int_bitsize;
         } else if (nr_bits > int_bitsize) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Invalid member bitfield_size");
                 return -EINVAL;
         }
 
         struct_size = struct_type->size;
         bytes_end = BITS_ROUNDUP_BYTES(struct_bits_off + nr_bits);
         if (struct_size < bytes_end) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static s32 btf_enum_check_meta(struct btf_verifier_env *env,
                                const struct btf_type *t,
                                u32 meta_left)
 {
         const struct btf_enum *enums = btf_type_enum(t);
         struct btf *btf = env->btf;
         const char *fmt_str;
         u16 i, nr_enums;
         u32 meta_needed;
 
         nr_enums = btf_type_vlen(t);
         meta_needed = nr_enums * sizeof(*enums);
 
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         if (t->size > 8 || !is_power_of_2(t->size)) {
                 btf_verifier_log_type(env, t, "Unexpected size");
                 return -EINVAL;
         }
 
         /* enum type either no name or a valid one */
         if (t->name_off &&
             !btf_name_valid_identifier(env->btf, t->name_off)) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         for (i = 0; i < nr_enums; i++) {
                 if (!btf_name_offset_valid(btf, enums[i].name_off)) {
                         btf_verifier_log(env, "\tInvalid name_offset:%u",
                                          enums[i].name_off);
                         return -EINVAL;
                 }
 
                 /* enum member must have a valid name */
                 if (!enums[i].name_off ||
                     !btf_name_valid_identifier(btf, enums[i].name_off)) {
                         btf_verifier_log_type(env, t, "Invalid name");
                         return -EINVAL;
                 }
 
                 if (env->log.level == BPF_LOG_KERNEL)
                         continue;
                 fmt_str = btf_type_kflag(t) ? "\t%s val=%d\n" : "\t%s val=%u\n";
                 btf_verifier_log(env, fmt_str,
                                  __btf_name_by_offset(btf, enums[i].name_off),
                                  enums[i].val);
         }
 
         return meta_needed;
 }
 
 static void btf_enum_log(struct btf_verifier_env *env,
                          const struct btf_type *t)
 {
         btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
 }
 
 static void btf_enum_show(const struct btf *btf, const struct btf_type *t,
                           u32 type_id, void *data, u8 bits_offset,
                           struct btf_show *show)
 {
         const struct btf_enum *enums = btf_type_enum(t);
         u32 i, nr_enums = btf_type_vlen(t);
         void *safe_data;
         int v;
 
         safe_data = btf_show_start_type(show, t, type_id, data);
         if (!safe_data)
                 return;
 
         v = *(int *)safe_data;
 
         for (i = 0; i < nr_enums; i++) {
                 if (v != enums[i].val)
                         continue;
 
                 btf_show_type_value(show, "%s",
                                     __btf_name_by_offset(btf,
                                                          enums[i].name_off));
 
                 btf_show_end_type(show);
                 return;
         }
 
         if (btf_type_kflag(t))
                 btf_show_type_value(show, "%d", v);
         else
                 btf_show_type_value(show, "%u", v);
         btf_show_end_type(show);
 }
 
 static struct btf_kind_operations enum_ops = {
         .check_meta = btf_enum_check_meta,
         .resolve = btf_df_resolve,
         .check_member = btf_enum_check_member,
         .check_kflag_member = btf_enum_check_kflag_member,
         .log_details = btf_enum_log,
         .show = btf_enum_show,
 };
 
 static s32 btf_enum64_check_meta(struct btf_verifier_env *env,
                                  const struct btf_type *t,
                                  u32 meta_left)
 {
         const struct btf_enum64 *enums = btf_type_enum64(t);
         struct btf *btf = env->btf;
         const char *fmt_str;
         u16 i, nr_enums;
         u32 meta_needed;
 
         nr_enums = btf_type_vlen(t);
         meta_needed = nr_enums * sizeof(*enums);
 
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         if (t->size > 8 || !is_power_of_2(t->size)) {
                 btf_verifier_log_type(env, t, "Unexpected size");
                 return -EINVAL;
         }
 
         /* enum type either no name or a valid one */
         if (t->name_off &&
             !btf_name_valid_identifier(env->btf, t->name_off)) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         for (i = 0; i < nr_enums; i++) {
                 if (!btf_name_offset_valid(btf, enums[i].name_off)) {
                         btf_verifier_log(env, "\tInvalid name_offset:%u",
                                          enums[i].name_off);
                         return -EINVAL;
                 }
 
                 /* enum member must have a valid name */
                 if (!enums[i].name_off ||
                     !btf_name_valid_identifier(btf, enums[i].name_off)) {
                         btf_verifier_log_type(env, t, "Invalid name");
                         return -EINVAL;
                 }
 
                 if (env->log.level == BPF_LOG_KERNEL)
                         continue;
 
                 fmt_str = btf_type_kflag(t) ? "\t%s val=%lld\n" : "\t%s val=%llu\n";
                 btf_verifier_log(env, fmt_str,
                                  __btf_name_by_offset(btf, enums[i].name_off),
                                  btf_enum64_value(enums + i));
         }
 
         return meta_needed;
 }
 
 static void btf_enum64_show(const struct btf *btf, const struct btf_type *t,
                             u32 type_id, void *data, u8 bits_offset,
                             struct btf_show *show)
 {
         const struct btf_enum64 *enums = btf_type_enum64(t);
         u32 i, nr_enums = btf_type_vlen(t);
         void *safe_data;
         s64 v;
 
         safe_data = btf_show_start_type(show, t, type_id, data);
         if (!safe_data)
                 return;
 
         v = *(u64 *)safe_data;
 
         for (i = 0; i < nr_enums; i++) {
                 if (v != btf_enum64_value(enums + i))
                         continue;
 
                 btf_show_type_value(show, "%s",
                                     __btf_name_by_offset(btf,
                                                          enums[i].name_off));
 
                 btf_show_end_type(show);
                 return;
         }
 
         if (btf_type_kflag(t))
                 btf_show_type_value(show, "%lld", v);
         else
                 btf_show_type_value(show, "%llu", v);
         btf_show_end_type(show);
 }
 
 static struct btf_kind_operations enum64_ops = {
         .check_meta = btf_enum64_check_meta,
         .resolve = btf_df_resolve,
         .check_member = btf_enum_check_member,
         .check_kflag_member = btf_enum_check_kflag_member,
         .log_details = btf_enum_log,
         .show = btf_enum64_show,
 };
 
 static s32 btf_func_proto_check_meta(struct btf_verifier_env *env,
                                      const struct btf_type *t,
                                      u32 meta_left)
 {
         u32 meta_needed = btf_type_vlen(t) * sizeof(struct btf_param);
 
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         if (t->name_off) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return meta_needed;
 }
 
 static void btf_func_proto_log(struct btf_verifier_env *env,
                                const struct btf_type *t)
 {
         const struct btf_param *args = (const struct btf_param *)(t + 1);
         u16 nr_args = btf_type_vlen(t), i;
 
         btf_verifier_log(env, "return=%u args=(", t->type);
         if (!nr_args) {
                 btf_verifier_log(env, "void");
                 goto done;
         }
 
         if (nr_args == 1 && !args[0].type) {
                 /* Only one vararg */
                 btf_verifier_log(env, "vararg");
                 goto done;
         }
 
         btf_verifier_log(env, "%u %s", args[0].type,
                          __btf_name_by_offset(env->btf,
                                               args[0].name_off));
         for (i = 1; i < nr_args - 1; i++)
                 btf_verifier_log(env, ", %u %s", args[i].type,
                                  __btf_name_by_offset(env->btf,
                                                       args[i].name_off));
 
         if (nr_args > 1) {
                 const struct btf_param *last_arg = &args[nr_args - 1];
 
                 if (last_arg->type)
                         btf_verifier_log(env, ", %u %s", last_arg->type,
                                          __btf_name_by_offset(env->btf,
                                                               last_arg->name_off));
                 else
                         btf_verifier_log(env, ", vararg");
         }
 
 done:
         btf_verifier_log(env, ")");
 }
 
 static struct btf_kind_operations func_proto_ops = {
         .check_meta = btf_func_proto_check_meta,
         .resolve = btf_df_resolve,
         /*
          * BTF_KIND_FUNC_PROTO cannot be directly referred by
          * a struct's member.
          *
          * It should be a function pointer instead.
          * (i.e. struct's member -> BTF_KIND_PTR -> BTF_KIND_FUNC_PROTO)
          *
          * Hence, there is no btf_func_check_member().
          */
         .check_member = btf_df_check_member,
         .check_kflag_member = btf_df_check_kflag_member,
         .log_details = btf_func_proto_log,
         .show = btf_df_show,
 };
 
 static s32 btf_func_check_meta(struct btf_verifier_env *env,
                                const struct btf_type *t,
                                u32 meta_left)
 {
         if (!t->name_off ||
             !btf_name_valid_identifier(env->btf, t->name_off)) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         if (btf_type_vlen(t) > BTF_FUNC_GLOBAL) {
                 btf_verifier_log_type(env, t, "Invalid func linkage");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return 0;
 }
 
 static int btf_func_resolve(struct btf_verifier_env *env,
                             const struct resolve_vertex *v)
 {
         const struct btf_type *t = v->t;
         u32 next_type_id = t->type;
         int err;
 
         err = btf_func_check(env, t);
         if (err)
                 return err;
 
         env_stack_pop_resolved(env, next_type_id, 0);
         return 0;
 }
 
 static struct btf_kind_operations func_ops = {
         .check_meta = btf_func_check_meta,
         .resolve = btf_func_resolve,
         .check_member = btf_df_check_member,
         .check_kflag_member = btf_df_check_kflag_member,
         .log_details = btf_ref_type_log,
         .show = btf_df_show,
 };
 
 static s32 btf_var_check_meta(struct btf_verifier_env *env,
                               const struct btf_type *t,
                               u32 meta_left)
 {
         const struct btf_var *var;
         u32 meta_needed = sizeof(*var);
 
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         if (btf_type_vlen(t)) {
                 btf_verifier_log_type(env, t, "vlen != 0");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         if (!t->name_off ||
             !__btf_name_valid(env->btf, t->name_off)) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         /* A var cannot be in type void */
         if (!t->type || !BTF_TYPE_ID_VALID(t->type)) {
                 btf_verifier_log_type(env, t, "Invalid type_id");
                 return -EINVAL;
         }
 
         var = btf_type_var(t);
         if (var->linkage != BTF_VAR_STATIC &&
             var->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
                 btf_verifier_log_type(env, t, "Linkage not supported");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return meta_needed;
 }
 
 static void btf_var_log(struct btf_verifier_env *env, const struct btf_type *t)
 {
         const struct btf_var *var = btf_type_var(t);
 
         btf_verifier_log(env, "type_id=%u linkage=%u", t->type, var->linkage);
 }
 
 static const struct btf_kind_operations var_ops = {
         .check_meta             = btf_var_check_meta,
         .resolve                = btf_var_resolve,
         .check_member           = btf_df_check_member,
         .check_kflag_member     = btf_df_check_kflag_member,
         .log_details            = btf_var_log,
         .show                   = btf_var_show,
 };
 
 static s32 btf_datasec_check_meta(struct btf_verifier_env *env,
                                   const struct btf_type *t,
                                   u32 meta_left)
 {
         const struct btf_var_secinfo *vsi;
         u64 last_vsi_end_off = 0, sum = 0;
         u32 i, meta_needed;
 
         meta_needed = btf_type_vlen(t) * sizeof(*vsi);
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         if (!t->size) {
                 btf_verifier_log_type(env, t, "size == 0");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         if (!t->name_off ||
             !btf_name_valid_section(env->btf, t->name_off)) {
                 btf_verifier_log_type(env, t, "Invalid name");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         for_each_vsi(i, t, vsi) {
                 /* A var cannot be in type void */
                 if (!vsi->type || !BTF_TYPE_ID_VALID(vsi->type)) {
                         btf_verifier_log_vsi(env, t, vsi,
                                              "Invalid type_id");
                         return -EINVAL;
                 }
 
                 if (vsi->offset < last_vsi_end_off || vsi->offset >= t->size) {
                         btf_verifier_log_vsi(env, t, vsi,
                                              "Invalid offset");
                         return -EINVAL;
                 }
 
                 if (!vsi->size || vsi->size > t->size) {
                         btf_verifier_log_vsi(env, t, vsi,
                                              "Invalid size");
                         return -EINVAL;
                 }
 
                 last_vsi_end_off = vsi->offset + vsi->size;
                 if (last_vsi_end_off > t->size) {
                         btf_verifier_log_vsi(env, t, vsi,
                                              "Invalid offset+size");
                         return -EINVAL;
                 }
 
                 btf_verifier_log_vsi(env, t, vsi, NULL);
                 sum += vsi->size;
         }
 
         if (t->size < sum) {
                 btf_verifier_log_type(env, t, "Invalid btf_info size");
                 return -EINVAL;
         }
 
         return meta_needed;
 }
 
 static int btf_datasec_resolve(struct btf_verifier_env *env,
                                const struct resolve_vertex *v)
 {
         const struct btf_var_secinfo *vsi;
         struct btf *btf = env->btf;
         u16 i;
 
         env->resolve_mode = RESOLVE_TBD;
         for_each_vsi_from(i, v->next_member, v->t, vsi) {
                 u32 var_type_id = vsi->type, type_id, type_size = 0;
                 const struct btf_type *var_type = btf_type_by_id(env->btf,
                                                                  var_type_id);
                 if (!var_type || !btf_type_is_var(var_type)) {
                         btf_verifier_log_vsi(env, v->t, vsi,
                                              "Not a VAR kind member");
                         return -EINVAL;
                 }
 
                 if (!env_type_is_resolve_sink(env, var_type) &&
                     !env_type_is_resolved(env, var_type_id)) {
                         env_stack_set_next_member(env, i + 1);
                         return env_stack_push(env, var_type, var_type_id);
                 }
 
                 type_id = var_type->type;
                 if (!btf_type_id_size(btf, &type_id, &type_size)) {
                         btf_verifier_log_vsi(env, v->t, vsi, "Invalid type");
                         return -EINVAL;
                 }
 
                 if (vsi->size < type_size) {
                         btf_verifier_log_vsi(env, v->t, vsi, "Invalid size");
                         return -EINVAL;
                 }
         }
 
         env_stack_pop_resolved(env, 0, 0);
         return 0;
 }
 
 static void btf_datasec_log(struct btf_verifier_env *env,
                             const struct btf_type *t)
 {
         btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
 }
 
 static void btf_datasec_show(const struct btf *btf,
                              const struct btf_type *t, u32 type_id,
                              void *data, u8 bits_offset,
                              struct btf_show *show)
 {
         const struct btf_var_secinfo *vsi;
         const struct btf_type *var;
         u32 i;
 
         if (!btf_show_start_type(show, t, type_id, data))
                 return;
 
         btf_show_type_value(show, "section (\"%s\") = {",
                             __btf_name_by_offset(btf, t->name_off));
         for_each_vsi(i, t, vsi) {
                 var = btf_type_by_id(btf, vsi->type);
                 if (i)
                         btf_show(show, ",");
                 btf_type_ops(var)->show(btf, var, vsi->type,
                                         data + vsi->offset, bits_offset, show);
         }
         btf_show_end_type(show);
 }
 
 static const struct btf_kind_operations datasec_ops = {
         .check_meta             = btf_datasec_check_meta,
         .resolve                = btf_datasec_resolve,
         .check_member           = btf_df_check_member,
         .check_kflag_member     = btf_df_check_kflag_member,
         .log_details            = btf_datasec_log,
         .show                   = btf_datasec_show,
 };
 
 static s32 btf_float_check_meta(struct btf_verifier_env *env,
                                 const struct btf_type *t,
                                 u32 meta_left)
 {
         if (btf_type_vlen(t)) {
                 btf_verifier_log_type(env, t, "vlen != 0");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         if (t->size != 2 && t->size != 4 && t->size != 8 && t->size != 12 &&
             t->size != 16) {
                 btf_verifier_log_type(env, t, "Invalid type_size");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return 0;
 }
 
 static int btf_float_check_member(struct btf_verifier_env *env,
                                   const struct btf_type *struct_type,
                                   const struct btf_member *member,
                                   const struct btf_type *member_type)
 {
         u64 start_offset_bytes;
         u64 end_offset_bytes;
         u64 misalign_bits;
         u64 align_bytes;
         u64 align_bits;
 
         /* Different architectures have different alignment requirements, so
          * here we check only for the reasonable minimum. This way we ensure
          * that types after CO-RE can pass the kernel BTF verifier.
          */
         align_bytes = min_t(u64, sizeof(void *), member_type->size);
         align_bits = align_bytes * BITS_PER_BYTE;
         div64_u64_rem(member->offset, align_bits, &misalign_bits);
         if (misalign_bits) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member is not properly aligned");
                 return -EINVAL;
         }
 
         start_offset_bytes = member->offset / BITS_PER_BYTE;
         end_offset_bytes = start_offset_bytes + member_type->size;
         if (end_offset_bytes > struct_type->size) {
                 btf_verifier_log_member(env, struct_type, member,
                                         "Member exceeds struct_size");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static void btf_float_log(struct btf_verifier_env *env,
                           const struct btf_type *t)
 {
         btf_verifier_log(env, "size=%u", t->size);
 }
 
 static const struct btf_kind_operations float_ops = {
         .check_meta = btf_float_check_meta,
         .resolve = btf_df_resolve,
         .check_member = btf_float_check_member,
         .check_kflag_member = btf_generic_check_kflag_member,
         .log_details = btf_float_log,
         .show = btf_df_show,
 };
 
 static s32 btf_decl_tag_check_meta(struct btf_verifier_env *env,
                               const struct btf_type *t,
                               u32 meta_left)
 {
         const struct btf_decl_tag *tag;
         u32 meta_needed = sizeof(*tag);
         s32 component_idx;
         const char *value;
 
         if (meta_left < meta_needed) {
                 btf_verifier_log_basic(env, t,
                                        "meta_left:%u meta_needed:%u",
                                        meta_left, meta_needed);
                 return -EINVAL;
         }
 
         value = btf_name_by_offset(env->btf, t->name_off);
         if (!value || !value[0]) {
                 btf_verifier_log_type(env, t, "Invalid value");
                 return -EINVAL;
         }
 
         if (btf_type_vlen(t)) {
                 btf_verifier_log_type(env, t, "vlen != 0");
                 return -EINVAL;
         }
 
         if (btf_type_kflag(t)) {
                 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
                 return -EINVAL;
         }
 
         component_idx = btf_type_decl_tag(t)->component_idx;
         if (component_idx < -1) {
                 btf_verifier_log_type(env, t, "Invalid component_idx");
                 return -EINVAL;
         }
 
         btf_verifier_log_type(env, t, NULL);
 
         return meta_needed;
 }
 
 static int btf_decl_tag_resolve(struct btf_verifier_env *env,
                            const struct resolve_vertex *v)
 {
         const struct btf_type *next_type;
         const struct btf_type *t = v->t;
         u32 next_type_id = t->type;
         struct btf *btf = env->btf;
         s32 component_idx;
         u32 vlen;
 
         next_type = btf_type_by_id(btf, next_type_id);
         if (!next_type || !btf_type_is_decl_tag_target(next_type)) {
                 btf_verifier_log_type(env, v->t, "Invalid type_id");
                 return -EINVAL;
         }
 
         if (!env_type_is_resolve_sink(env, next_type) &&
             !env_type_is_resolved(env, next_type_id))
                 return env_stack_push(env, next_type, next_type_id);
 
         component_idx = btf_type_decl_tag(t)->component_idx;
         if (component_idx != -1) {
                 if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {
                         btf_verifier_log_type(env, v->t, "Invalid component_idx");
                         return -EINVAL;
                 }
 
                 if (btf_type_is_struct(next_type)) {
                         vlen = btf_type_vlen(next_type);
                 } else {
                         /* next_type should be a function */
                         next_type = btf_type_by_id(btf, next_type->type);
                         vlen = btf_type_vlen(next_type);
                 }
 
                 if ((u32)component_idx >= vlen) {
                         btf_verifier_log_type(env, v->t, "Invalid component_idx");
                         return -EINVAL;
                 }
         }
 
         env_stack_pop_resolved(env, next_type_id, 0);
 
         return 0;
 }
 
 static void btf_decl_tag_log(struct btf_verifier_env *env, const struct btf_type *t)
 {
         btf_verifier_log(env, "type=%u component_idx=%d", t->type,
                          btf_type_decl_tag(t)->component_idx);
 }
 
 static const struct btf_kind_operations decl_tag_ops = {
         .check_meta = btf_decl_tag_check_meta,
         .resolve = btf_decl_tag_resolve,
         .check_member = btf_df_check_member,
         .check_kflag_member = btf_df_check_kflag_member,
         .log_details = btf_decl_tag_log,
         .show = btf_df_show,
 };
 
 static int btf_func_proto_check(struct btf_verifier_env *env,
                                 const struct btf_type *t)
 {
         const struct btf_type *ret_type;
         const struct btf_param *args;
         const struct btf *btf;
         u16 nr_args, i;
         int err;
 
         btf = env->btf;
         args = (const struct btf_param *)(t + 1);
         nr_args = btf_type_vlen(t);
 
         /* Check func return type which could be "void" (t->type == 0) */
         if (t->type) {
                 u32 ret_type_id = t->type;
 
                 ret_type = btf_type_by_id(btf, ret_type_id);
                 if (!ret_type) {
                         btf_verifier_log_type(env, t, "Invalid return type");
                         return -EINVAL;
                 }
 
                 if (btf_type_is_resolve_source_only(ret_type)) {
                         btf_verifier_log_type(env, t, "Invalid return type");
                         return -EINVAL;
                 }
 
                 if (btf_type_needs_resolve(ret_type) &&
                     !env_type_is_resolved(env, ret_type_id)) {
                         err = btf_resolve(env, ret_type, ret_type_id);
                         if (err)
                                 return err;
                 }
 
                 /* Ensure the return type is a type that has a size */
                 if (!btf_type_id_size(btf, &ret_type_id, NULL)) {
                         btf_verifier_log_type(env, t, "Invalid return type");
                         return -EINVAL;
                 }
         }
 
         if (!nr_args)
                 return 0;
 
         /* Last func arg type_id could be 0 if it is a vararg */
         if (!args[nr_args - 1].type) {
                 if (args[nr_args - 1].name_off) {
                         btf_verifier_log_type(env, t, "Invalid arg#%u",
                                               nr_args);
                         return -EINVAL;
                 }
                 nr_args--;
         }
 
         for (i = 0; i < nr_args; i++) {
                 const struct btf_type *arg_type;
                 u32 arg_type_id;
 
                 arg_type_id = args[i].type;
                 arg_type = btf_type_by_id(btf, arg_type_id);
                 if (!arg_type) {
                         btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
                         return -EINVAL;
                 }
 
                 if (btf_type_is_resolve_source_only(arg_type)) {
                         btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
                         return -EINVAL;
                 }
 
                 if (args[i].name_off &&
                     (!btf_name_offset_valid(btf, args[i].name_off) ||
                      !btf_name_valid_identifier(btf, args[i].name_off))) {
                         btf_verifier_log_type(env, t,
                                               "Invalid arg#%u", i + 1);
                         return -EINVAL;
                 }
 
                 if (btf_type_needs_resolve(arg_type) &&
                     !env_type_is_resolved(env, arg_type_id)) {
                         err = btf_resolve(env, arg_type, arg_type_id);
                         if (err)
                                 return err;
                 }
 
                 if (!btf_type_id_size(btf, &arg_type_id, NULL)) {
                         btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
                         return -EINVAL;
                 }
         }
 
         return 0;
 }
 
 static int btf_func_check(struct btf_verifier_env *env,
                           const struct btf_type *t)
 {
         const struct btf_type *proto_type;
         const struct btf_param *args;
         const struct btf *btf;
         u16 nr_args, i;
 
         btf = env->btf;
         proto_type = btf_type_by_id(btf, t->type);
 
         if (!proto_type || !btf_type_is_func_proto(proto_type)) {
                 btf_verifier_log_type(env, t, "Invalid type_id");
                 return -EINVAL;
         }
 
         args = (const struct btf_param *)(proto_type + 1);
         nr_args = btf_type_vlen(proto_type);
         for (i = 0; i < nr_args; i++) {
                 if (!args[i].name_off && args[i].type) {
                         btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
                         return -EINVAL;
                 }
         }
 
         return 0;
 }
 
 static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
         [BTF_KIND_INT] = &int_ops,
         [BTF_KIND_PTR] = &ptr_ops,
         [BTF_KIND_ARRAY] = &array_ops,
         [BTF_KIND_STRUCT] = &struct_ops,
         [BTF_KIND_UNION] = &struct_ops,
         [BTF_KIND_ENUM] = &enum_ops,
         [BTF_KIND_FWD] = &fwd_ops,
         [BTF_KIND_TYPEDEF] = &modifier_ops,
         [BTF_KIND_VOLATILE] = &modifier_ops,
         [BTF_KIND_CONST] = &modifier_ops,
         [BTF_KIND_RESTRICT] = &modifier_ops,
         [BTF_KIND_FUNC] = &func_ops,
         [BTF_KIND_FUNC_PROTO] = &func_proto_ops,
         [BTF_KIND_VAR] = &var_ops,
         [BTF_KIND_DATASEC] = &datasec_ops,
         [BTF_KIND_FLOAT] = &float_ops,
         [BTF_KIND_DECL_TAG] = &decl_tag_ops,
         [BTF_KIND_TYPE_TAG] = &modifier_ops,
         [BTF_KIND_ENUM64] = &enum64_ops,
 };
 
 static s32 btf_check_meta(struct btf_verifier_env *env,
                           const struct btf_type *t,
                           u32 meta_left)
 {
         u32 saved_meta_left = meta_left;
         s32 var_meta_size;
 
         if (meta_left < sizeof(*t)) {
                 btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
                                  env->log_type_id, meta_left, sizeof(*t));
                 return -EINVAL;
         }
         meta_left -= sizeof(*t);
 
         if (t->info & ~BTF_INFO_MASK) {
                 btf_verifier_log(env, "[%u] Invalid btf_info:%x",
                                  env->log_type_id, t->info);
                 return -EINVAL;
         }
 
         if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
             BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
                 btf_verifier_log(env, "[%u] Invalid kind:%u",
                                  env->log_type_id, BTF_INFO_KIND(t->info));
                 return -EINVAL;
         }
 
         if (!btf_name_offset_valid(env->btf, t->name_off)) {
                 btf_verifier_log(env, "[%u] Invalid name_offset:%u",
                                  env->log_type_id, t->name_off);
                 return -EINVAL;
         }
 
         var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
         if (var_meta_size < 0)
                 return var_meta_size;
 
         meta_left -= var_meta_size;
 
         return saved_meta_left - meta_left;
 }
 
 static int btf_check_all_metas(struct btf_verifier_env *env)
 {
         struct btf *btf = env->btf;
         struct btf_header *hdr;
         void *cur, *end;
 
         hdr = &btf->hdr;
         cur = btf->nohdr_data + hdr->type_off;
         end = cur + hdr->type_len;
 
         env->log_type_id = btf->base_btf ? btf->start_id : 1;
         while (cur < end) {
                 struct btf_type *t = cur;
                 s32 meta_size;
 
                 meta_size = btf_check_meta(env, t, end - cur);
                 if (meta_size < 0)
                         return meta_size;
 
                 btf_add_type(env, t);
                 cur += meta_size;
                 env->log_type_id++;
         }
 
         return 0;
 }
 
 static bool btf_resolve_valid(struct btf_verifier_env *env,
                               const struct btf_type *t,
                               u32 type_id)
 {
         struct btf *btf = env->btf;
 
         if (!env_type_is_resolved(env, type_id))
                 return false;
 
         if (btf_type_is_struct(t) || btf_type_is_datasec(t))
                 return !btf_resolved_type_id(btf, type_id) &&
                        !btf_resolved_type_size(btf, type_id);
 
         if (btf_type_is_decl_tag(t) || btf_type_is_func(t))
                 return btf_resolved_type_id(btf, type_id) &&
                        !btf_resolved_type_size(btf, type_id);
 
         if (btf_type_is_modifier(t) || btf_type_is_ptr(t) ||
             btf_type_is_var(t)) {
                 t = btf_type_id_resolve(btf, &type_id);
                 return t &&
                        !btf_type_is_modifier(t) &&
                        !btf_type_is_var(t) &&
                        !btf_type_is_datasec(t);
         }
 
         if (btf_type_is_array(t)) {
                 const struct btf_array *array = btf_type_array(t);
                 const struct btf_type *elem_type;
                 u32 elem_type_id = array->type;
                 u32 elem_size;
 
                 elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
                 return elem_type && !btf_type_is_modifier(elem_type) &&
                         (array->nelems * elem_size ==
                          btf_resolved_type_size(btf, type_id));
         }
 
         return false;
 }
 
 static int btf_resolve(struct btf_verifier_env *env,
                        const struct btf_type *t, u32 type_id)
 {
         u32 save_log_type_id = env->log_type_id;
         const struct resolve_vertex *v;
         int err = 0;
 
         env->resolve_mode = RESOLVE_TBD;
         env_stack_push(env, t, type_id);
         while (!err && (v = env_stack_peak(env))) {
                 env->log_type_id = v->type_id;
                 err = btf_type_ops(v->t)->resolve(env, v);
         }
 
         env->log_type_id = type_id;
         if (err == -E2BIG) {
                 btf_verifier_log_type(env, t,
                                       "Exceeded max resolving depth:%u",
                                       MAX_RESOLVE_DEPTH);
         } else if (err == -EEXIST) {
                 btf_verifier_log_type(env, t, "Loop detected");
         }
 
         /* Final sanity check */
         if (!err && !btf_resolve_valid(env, t, type_id)) {
                 btf_verifier_log_type(env, t, "Invalid resolve state");
                 err = -EINVAL;
         }
 
         env->log_type_id = save_log_type_id;
         return err;
 }
 
 static int btf_check_all_types(struct btf_verifier_env *env)
 {
         struct btf *btf = env->btf;
         const struct btf_type *t;
         u32 type_id, i;
         int err;
 
         err = env_resolve_init(env);
         if (err)
                 return err;
 
         env->phase++;
         for (i = btf->base_btf ? 0 : 1; i < btf->nr_types; i++) {
                 type_id = btf->start_id + i;
                 t = btf_type_by_id(btf, type_id);
 
                 env->log_type_id = type_id;
                 if (btf_type_needs_resolve(t) &&
                     !env_type_is_resolved(env, type_id)) {
                         err = btf_resolve(env, t, type_id);
                         if (err)
                                 return err;
                 }
 
                 if (btf_type_is_func_proto(t)) {
                         err = btf_func_proto_check(env, t);
                         if (err)
                                 return err;
                 }
         }
 
         return 0;
 }
 
 static int btf_parse_type_sec(struct btf_verifier_env *env)
 {
         const struct btf_header *hdr = &env->btf->hdr;
         int err;
 
         /* Type section must align to 4 bytes */
         if (hdr->type_off & (sizeof(u32) - 1)) {
                 btf_verifier_log(env, "Unaligned type_off");
                 return -EINVAL;
         }
 
         if (!env->btf->base_btf && !hdr->type_len) {
                 btf_verifier_log(env, "No type found");
                 return -EINVAL;
         }
 
         err = btf_check_all_metas(env);
         if (err)
                 return err;
 
         return btf_check_all_types(env);
 }
 
 static int btf_parse_str_sec(struct btf_verifier_env *env)
 {
         const struct btf_header *hdr;
         struct btf *btf = env->btf;
         const char *start, *end;
 
         hdr = &btf->hdr;
         start = btf->nohdr_data + hdr->str_off;
         end = start + hdr->str_len;
 
         if (end != btf->data + btf->data_size) {
                 btf_verifier_log(env, "String section is not at the end");
                 return -EINVAL;
         }
 
         btf->strings = start;
 
         if (btf->base_btf && !hdr->str_len)
                 return 0;
         if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET || end[-1]) {
                 btf_verifier_log(env, "Invalid string section");
                 return -EINVAL;
         }
         if (!btf->base_btf && start[0]) {
                 btf_verifier_log(env, "Invalid string section");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static const size_t btf_sec_info_offset[] = {
         offsetof(struct btf_header, type_off),
         offsetof(struct btf_header, str_off),
 };
 
 static int btf_sec_info_cmp(const void *a, const void *b)
 {
         const struct btf_sec_info *x = a;
         const struct btf_sec_info *y = b;
 
         return (int)(x->off - y->off) ? : (int)(x->len - y->len);
 }
 
 static int btf_check_sec_info(struct btf_verifier_env *env,
                               u32 btf_data_size)
 {
         struct btf_sec_info secs[ARRAY_SIZE(btf_sec_info_offset)];
         u32 total, expected_total, i;
         const struct btf_header *hdr;
         const struct btf *btf;
 
         btf = env->btf;
         hdr = &btf->hdr;
 
         /* Populate the secs from hdr */
         for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++)
                 secs[i] = *(struct btf_sec_info *)((void *)hdr +
                                                    btf_sec_info_offset[i]);
 
         sort(secs, ARRAY_SIZE(btf_sec_info_offset),
              sizeof(struct btf_sec_info), btf_sec_info_cmp, NULL);
 
         /* Check for gaps and overlap among sections */
         total = 0;
         expected_total = btf_data_size - hdr->hdr_len;
         for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++) {
                 if (expected_total < secs[i].off) {
                         btf_verifier_log(env, "Invalid section offset");
                         return -EINVAL;
                 }
                 if (total < secs[i].off) {
                         /* gap */
                         btf_verifier_log(env, "Unsupported section found");
                         return -EINVAL;
                 }
                 if (total > secs[i].off) {
                         btf_verifier_log(env, "Section overlap found");
                         return -EINVAL;
                 }
                 if (expected_total - total < secs[i].len) {
                         btf_verifier_log(env,
                                          "Total section length too long");
                         return -EINVAL;
                 }
                 total += secs[i].len;
         }
 
         /* There is data other than hdr and known sections */
         if (expected_total != total) {
                 btf_verifier_log(env, "Unsupported section found");
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static int btf_parse_hdr(struct btf_verifier_env *env)
 {
         u32 hdr_len, hdr_copy, btf_data_size;
         const struct btf_header *hdr;
         struct btf *btf;
 
         btf = env->btf;
         btf_data_size = btf->data_size;
 
         if (btf_data_size < offsetofend(struct btf_header, hdr_len)) {
                 btf_verifier_log(env, "hdr_len not found");
                 return -EINVAL;
         }
 
         hdr = btf->data;
         hdr_len = hdr->hdr_len;
         if (btf_data_size < hdr_len) {
                 btf_verifier_log(env, "btf_header not found");
                 return -EINVAL;
         }
 
         /* Ensure the unsupported header fields are zero */
         if (hdr_len > sizeof(btf->hdr)) {
                 u8 *expected_zero = btf->data + sizeof(btf->hdr);
                 u8 *end = btf->data + hdr_len;
 
                 for (; expected_zero < end; expected_zero++) {
                         if (*expected_zero) {
                                 btf_verifier_log(env, "Unsupported btf_header");
                                 return -E2BIG;
                         }
                 }
         }
 
         hdr_copy = min_t(u32, hdr_len, sizeof(btf->hdr));
         memcpy(&btf->hdr, btf->data, hdr_copy);
 
         hdr = &btf->hdr;
 
         btf_verifier_log_hdr(env, btf_data_size);
 
         if (hdr->magic != BTF_MAGIC) {
                 btf_verifier_log(env, "Invalid magic");
                 return -EINVAL;
         }
 
         if (hdr->version != BTF_VERSION) {
                 btf_verifier_log(env, "Unsupported version");
                 return -ENOTSUPP;
         }
 
         if (hdr->flags) {
                 btf_verifier_log(env, "Unsupported flags");
                 return -ENOTSUPP;
         }
 
         if (!btf->base_btf && btf_data_size == hdr->hdr_len) {
                 btf_verifier_log(env, "No data");
                 return -EINVAL;
         }
 
         return btf_check_sec_info(env, btf_data_size);
 }
 
 static const char *alloc_obj_fields[] = {
         "bpf_spin_lock",
         "bpf_list_head",
         "bpf_list_node",
         "bpf_rb_root",
         "bpf_rb_node",
         "bpf_refcount",
 };
 
 static struct btf_struct_metas *
 btf_parse_struct_metas(struct bpf_verifier_log *log, struct btf *btf)
 {
         union {
                 struct btf_id_set set;
                 struct {
                         u32 _cnt;
                         u32 _ids[ARRAY_SIZE(alloc_obj_fields)];
                 } _arr;
         } aof;
         struct btf_struct_metas *tab = NULL;
         int i, n, id, ret;
 
         BUILD_BUG_ON(offsetof(struct btf_id_set, cnt) != 0);
         BUILD_BUG_ON(sizeof(struct btf_id_set) != sizeof(u32));
 
         memset(&aof, 0, sizeof(aof));
         for (i = 0; i < ARRAY_SIZE(alloc_obj_fields); i++) {
                 /* Try to find whether this special type exists in user BTF, and
                  * if so remember its ID so we can easily find it among members
                  * of structs that we iterate in the next loop.
                  */
                 id = btf_find_by_name_kind(btf, alloc_obj_fields[i], BTF_KIND_STRUCT);
                 if (id < 0)
                         continue;
                 aof.set.ids[aof.set.cnt++] = id;
         }
 
         if (!aof.set.cnt)
                 return NULL;
         sort(&aof.set.ids, aof.set.cnt, sizeof(aof.set.ids[0]), btf_id_cmp_func, NULL);
 
         n = btf_nr_types(btf);
         for (i = 1; i < n; i++) {
                 struct btf_struct_metas *new_tab;
                 const struct btf_member *member;
                 struct btf_struct_meta *type;
                 struct btf_record *record;
                 const struct btf_type *t;
                 int j, tab_cnt;
 
                 t = btf_type_by_id(btf, i);
                 if (!t) {
                         ret = -EINVAL;
                         goto free;
                 }
                 if (!__btf_type_is_struct(t))
                         continue;
 
                 cond_resched();
 
                 for_each_member(j, t, member) {
                         if (btf_id_set_contains(&aof.set, member->type))
                                 goto parse;
                 }
                 continue;
         parse:
                 tab_cnt = tab ? tab->cnt : 0;
                 new_tab = krealloc(tab, offsetof(struct btf_struct_metas, types[tab_cnt + 1]),
                                    GFP_KERNEL | __GFP_NOWARN);
                 if (!new_tab) {
                         ret = -ENOMEM;
                         goto free;
                 }
                 if (!tab)
                         new_tab->cnt = 0;
                 tab = new_tab;
 
                 type = &tab->types[tab->cnt];
                 type->btf_id = i;
                 record = btf_parse_fields(btf, t, BPF_SPIN_LOCK | BPF_LIST_HEAD | BPF_LIST_NODE |
                                                   BPF_RB_ROOT | BPF_RB_NODE | BPF_REFCOUNT, t->size);
                 /* The record cannot be unset, treat it as an error if so */
                 if (IS_ERR_OR_NULL(record)) {
                         ret = PTR_ERR_OR_ZERO(record) ?: -EFAULT;
                         goto free;
                 }
                 type->record = record;
                 tab->cnt++;
         }
         return tab;
 free:
         btf_struct_metas_free(tab);
         return ERR_PTR(ret);
 }
 
 struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id)
 {
         struct btf_struct_metas *tab;
 
         BUILD_BUG_ON(offsetof(struct btf_struct_meta, btf_id) != 0);
         tab = btf->struct_meta_tab;
         if (!tab)
                 return NULL;
         return bsearch(&btf_id, tab->types, tab->cnt, sizeof(tab->types[0]), btf_id_cmp_func);
 }
 
 static int btf_check_type_tags(struct btf_verifier_env *env,
                                struct btf *btf, int start_id)
 {
         int i, n, good_id = start_id - 1;
         bool in_tags;
 
         n = btf_nr_types(btf);
         for (i = start_id; i < n; i++) {
                 const struct btf_type *t;
                 int chain_limit = 32;
                 u32 cur_id = i;
 
                 t = btf_type_by_id(btf, i);
                 if (!t)
                         return -EINVAL;
                 if (!btf_type_is_modifier(t))
                         continue;
 
                 cond_resched();
 
                 in_tags = btf_type_is_type_tag(t);
                 while (btf_type_is_modifier(t)) {
                         if (!chain_limit--) {
                                 btf_verifier_log(env, "Max chain length or cycle detected");
                                 return -ELOOP;
                         }
                         if (btf_type_is_type_tag(t)) {
                                 if (!in_tags) {
                                         btf_verifier_log(env, "Type tags don't precede modifiers");
                                         return -EINVAL;
                                 }
                         } else if (in_tags) {
                                 in_tags = false;
                         }
                         if (cur_id <= good_id)
                                 break;
                         /* Move to next type */
                         cur_id = t->type;
                         t = btf_type_by_id(btf, cur_id);
                         if (!t)
                                 return -EINVAL;
                 }
                 good_id = i;
         }
         return 0;
 }
 
 static int finalize_log(struct bpf_verifier_log *log, bpfptr_t uattr, u32 uattr_size)
 {
         u32 log_true_size;
         int err;
 
         err = bpf_vlog_finalize(log, &log_true_size);
 
         if (uattr_size >= offsetofend(union bpf_attr, btf_log_true_size) &&
             copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, btf_log_true_size),
                                   &log_true_size, sizeof(log_true_size)))
                 err = -EFAULT;
 
         return err;
 }
 
 static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
 {
         bpfptr_t btf_data = make_bpfptr(attr->btf, uattr.is_kernel);
         char __user *log_ubuf = u64_to_user_ptr(attr->btf_log_buf);
         struct btf_struct_metas *struct_meta_tab;
         struct btf_verifier_env *env = NULL;
         struct btf *btf = NULL;
         u8 *data;
         int err, ret;
 
         if (attr->btf_size > BTF_MAX_SIZE)
                 return ERR_PTR(-E2BIG);
 
         env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
         if (!env)
                 return ERR_PTR(-ENOMEM);
 
         /* user could have requested verbose verifier output
          * and supplied buffer to store the verification trace
          */
         err = bpf_vlog_init(&env->log, attr->btf_log_level,
                             log_ubuf, attr->btf_log_size);
         if (err)
                 goto errout_free;
 
         btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
         if (!btf) {
                 err = -ENOMEM;
                 goto errout;
         }
         env->btf = btf;
 
         data = kvmalloc(attr->btf_size, GFP_KERNEL | __GFP_NOWARN);
         if (!data) {
                 err = -ENOMEM;
                 goto errout;
         }
 
         btf->data = data;
         btf->data_size = attr->btf_size;
 
         if (copy_from_bpfptr(data, btf_data, attr->btf_size)) {
                 err = -EFAULT;
                 goto errout;
         }
 
         err = btf_parse_hdr(env);
         if (err)
                 goto errout;
 
         btf->nohdr_data = btf->data + btf->hdr.hdr_len;
 
         err = btf_parse_str_sec(env);
         if (err)
                 goto errout;
 
         err = btf_parse_type_sec(env);
         if (err)
                 goto errout;
 
         err = btf_check_type_tags(env, btf, 1);
         if (err)
                 goto errout;
 
         struct_meta_tab = btf_parse_struct_metas(&env->log, btf);
         if (IS_ERR(struct_meta_tab)) {
                 err = PTR_ERR(struct_meta_tab);
                 goto errout;
         }
         btf->struct_meta_tab = struct_meta_tab;
 
         if (struct_meta_tab) {
                 int i;
 
                 for (i = 0; i < struct_meta_tab->cnt; i++) {
                         err = btf_check_and_fixup_fields(btf, struct_meta_tab->types[i].record);
                         if (err < 0)
                                 goto errout_meta;
                 }
         }
 
         err = finalize_log(&env->log, uattr, uattr_size);
         if (err)
                 goto errout_free;
 
         btf_verifier_env_free(env);
         refcount_set(&btf->refcnt, 1);
         return btf;
 
 errout_meta:
         btf_free_struct_meta_tab(btf);
 errout:
         /* overwrite err with -ENOSPC or -EFAULT */
         ret = finalize_log(&env->log, uattr, uattr_size);
         if (ret)
                 err = ret;
 errout_free:
         btf_verifier_env_free(env);
         if (btf)
                 btf_free(btf);
         return ERR_PTR(err);
 }
 
 extern char __start_BTF[];
 extern char __stop_BTF[];
 extern struct btf *btf_vmlinux;
 
 #define BPF_MAP_TYPE(_id, _ops)
 #define BPF_LINK_TYPE(_id, _name)
 static union {
         struct bpf_ctx_convert {
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
         prog_ctx_type _id##_prog; \
         kern_ctx_type _id##_kern;
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
         } *__t;
         /* 't' is written once under lock. Read many times. */
         const struct btf_type *t;
 } bpf_ctx_convert;
 enum {
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
         __ctx_convert##_id,
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
         __ctx_convert_unused, /* to avoid empty enum in extreme .config */
 };
 static u8 bpf_ctx_convert_map[] = {
 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
         [_id] = __ctx_convert##_id,
 #include <linux/bpf_types.h>
 #undef BPF_PROG_TYPE
         0, /* avoid empty array */
 };
 #undef BPF_MAP_TYPE
 #undef BPF_LINK_TYPE
 
 static const struct btf_type *find_canonical_prog_ctx_type(enum bpf_prog_type prog_type)
 {
         const struct btf_type *conv_struct;
         const struct btf_member *ctx_type;
 
         conv_struct = bpf_ctx_convert.t;
         if (!conv_struct)
                 return NULL;
         /* prog_type is valid bpf program type. No need for bounds check. */
         ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;
         /* ctx_type is a pointer to prog_ctx_type in vmlinux.
          * Like 'struct __sk_buff'
          */
         return btf_type_by_id(btf_vmlinux, ctx_type->type);
 }
 
 static int find_kern_ctx_type_id(enum bpf_prog_type prog_type)
 {
         const struct btf_type *conv_struct;
         const struct btf_member *ctx_type;
 
         conv_struct = bpf_ctx_convert.t;
         if (!conv_struct)
                 return -EFAULT;
         /* prog_type is valid bpf program type. No need for bounds check. */
         ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2 + 1;
         /* ctx_type is a pointer to prog_ctx_type in vmlinux.
          * Like 'struct sk_buff'
          */
         return ctx_type->type;
 }
 
 bool btf_is_projection_of(const char *pname, const char *tname)
 {
         if (strcmp(pname, "__sk_buff") == 0 && strcmp(tname, "sk_buff") == 0)
                 return true;
         if (strcmp(pname, "xdp_md") == 0 && strcmp(tname, "xdp_buff") == 0)
                 return true;
         return false;
 }
 
 bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
                           const struct btf_type *t, enum bpf_prog_type prog_type,
                           int arg)
 {
         const struct btf_type *ctx_type;
         const char *tname, *ctx_tname;
 
         t = btf_type_by_id(btf, t->type);
 
         /* KPROBE programs allow bpf_user_pt_regs_t typedef, which we need to
          * check before we skip all the typedef below.
          */
         if (prog_type == BPF_PROG_TYPE_KPROBE) {
                 while (btf_type_is_modifier(t) && !btf_type_is_typedef(t))
                         t = btf_type_by_id(btf, t->type);
 
                 if (btf_type_is_typedef(t)) {
                         tname = btf_name_by_offset(btf, t->name_off);
                         if (tname && strcmp(tname, "bpf_user_pt_regs_t") == 0)
                                 return true;
                 }
         }
 
         while (btf_type_is_modifier(t))
                 t = btf_type_by_id(btf, t->type);
         if (!btf_type_is_struct(t)) {
                 /* Only pointer to struct is supported for now.
                  * That means that BPF_PROG_TYPE_TRACEPOINT with BTF
                  * is not supported yet.
                  * BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
                  */
                 return false;
         }
         tname = btf_name_by_offset(btf, t->name_off);
         if (!tname) {
                 bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
                 return false;
         }
 
         ctx_type = find_canonical_prog_ctx_type(prog_type);
         if (!ctx_type) {
                 bpf_log(log, "btf_vmlinux is malformed\n");
                 /* should not happen */
                 return false;
         }
 again:
         ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_type->name_off);
         if (!ctx_tname) {
                 /* should not happen */
                 bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
                 return false;
         }
         /* program types without named context types work only with arg:ctx tag */
         if (ctx_tname[0] == '\0')
                 return false;
         /* only compare that prog's ctx type name is the same as
          * kernel expects. No need to compare field by field.
          * It's ok for bpf prog to do:
          * struct __sk_buff {};
          * int socket_filter_bpf_prog(struct __sk_buff *skb)
          * { // no fields of skb are ever used }
          */
         if (btf_is_projection_of(ctx_tname, tname))
                 return true;
         if (strcmp(ctx_tname, tname)) {
                 /* bpf_user_pt_regs_t is a typedef, so resolve it to
                  * underlying struct and check name again
                  */
                 if (!btf_type_is_modifier(ctx_type))
                         return false;
                 while (btf_type_is_modifier(ctx_type))
                         ctx_type = btf_type_by_id(btf_vmlinux, ctx_type->type);
                 goto again;
         }
         return true;
 }
 
 /* forward declarations for arch-specific underlying types of
  * bpf_user_pt_regs_t; this avoids the need for arch-specific #ifdef
  * compilation guards below for BPF_PROG_TYPE_PERF_EVENT checks, but still
  * works correctly with __builtin_types_compatible_p() on respective
  * architectures
  */
 struct user_regs_struct;
 struct user_pt_regs;
 
 static int btf_validate_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
                                       const struct btf_type *t, int arg,
                                       enum bpf_prog_type prog_type,
                                       enum bpf_attach_type attach_type)
 {
         const struct btf_type *ctx_type;
         const char *tname, *ctx_tname;
 
         if (!btf_is_ptr(t)) {
                 bpf_log(log, "arg#%d type isn't a pointer\n", arg);
                 return -EINVAL;
         }
         t = btf_type_by_id(btf, t->type);
 
         /* KPROBE and PERF_EVENT programs allow bpf_user_pt_regs_t typedef */
         if (prog_type == BPF_PROG_TYPE_KPROBE || prog_type == BPF_PROG_TYPE_PERF_EVENT) {
                 while (btf_type_is_modifier(t) && !btf_type_is_typedef(t))
                         t = btf_type_by_id(btf, t->type);
 
                 if (btf_type_is_typedef(t)) {
                         tname = btf_name_by_offset(btf, t->name_off);
                         if (tname && strcmp(tname, "bpf_user_pt_regs_t") == 0)
                                 return 0;
                 }
         }
 
         /* all other program types don't use typedefs for context type */
         while (btf_type_is_modifier(t))
                 t = btf_type_by_id(btf, t->type);
 
         /* `void *ctx __arg_ctx` is always valid */
         if (btf_type_is_void(t))
                 return 0;
 
         tname = btf_name_by_offset(btf, t->name_off);
         if (str_is_empty(tname)) {
                 bpf_log(log, "arg#%d type doesn't have a name\n", arg);
                 return -EINVAL;
         }
 
         /* special cases */
         switch (prog_type) {
         case BPF_PROG_TYPE_KPROBE:
                 if (__btf_type_is_struct(t) && strcmp(tname, "pt_regs") == 0)
                         return 0;
                 break;
         case BPF_PROG_TYPE_PERF_EVENT:
                 if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct pt_regs) &&
                     __btf_type_is_struct(t) && strcmp(tname, "pt_regs") == 0)
                         return 0;
                 if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_pt_regs) &&
                     __btf_type_is_struct(t) && strcmp(tname, "user_pt_regs") == 0)
                         return 0;
                 if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_regs_struct) &&
                     __btf_type_is_struct(t) && strcmp(tname, "user_regs_struct") == 0)
                         return 0;
                 break;
         case BPF_PROG_TYPE_RAW_TRACEPOINT:
         case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
                 /* allow u64* as ctx */
                 if (btf_is_int(t) && t->size == 8)
                         return 0;
                 break;
         case BPF_PROG_TYPE_TRACING:
                 switch (attach_type) {
                 case BPF_TRACE_RAW_TP:
                         /* tp_btf program is TRACING, so need special case here */
                         if (__btf_type_is_struct(t) &&
                             strcmp(tname, "bpf_raw_tracepoint_args") == 0)
                                 return 0;
                         /* allow u64* as ctx */
                         if (btf_is_int(t) && t->size == 8)
                                 return 0;
                         break;
                 case BPF_TRACE_ITER:
                         /* allow struct bpf_iter__xxx types only */
                         if (__btf_type_is_struct(t) &&
                             strncmp(tname, "bpf_iter__", sizeof("bpf_iter__") - 1) == 0)
                                 return 0;
                         break;
                 case BPF_TRACE_FENTRY:
                 case BPF_TRACE_FEXIT:
                 case BPF_MODIFY_RETURN:
                         /* allow u64* as ctx */
                         if (btf_is_int(t) && t->size == 8)
                                 return 0;
                         break;
                 default:
                         break;
                 }
                 break;
         case BPF_PROG_TYPE_LSM:
         case BPF_PROG_TYPE_STRUCT_OPS:
                 /* allow u64* as ctx */
                 if (btf_is_int(t) && t->size == 8)
                         return 0;
                 break;
         case BPF_PROG_TYPE_TRACEPOINT:
         case BPF_PROG_TYPE_SYSCALL:
         case BPF_PROG_TYPE_EXT:
                 return 0; /* anything goes */
         default:
                 break;
         }
 
         ctx_type = find_canonical_prog_ctx_type(prog_type);
         if (!ctx_type) {
                 /* should not happen */
                 bpf_log(log, "btf_vmlinux is malformed\n");
                 return -EINVAL;
         }
 
         /* resolve typedefs and check that underlying structs are matching as well */
         while (btf_type_is_modifier(ctx_type))
                 ctx_type = btf_type_by_id(btf_vmlinux, ctx_type->type);
 
         /* if program type doesn't have distinctly named struct type for
          * context, then __arg_ctx argument can only be `void *`, which we
          * already checked above
          */
         if (!__btf_type_is_struct(ctx_type)) {
                 bpf_log(log, "arg#%d should be void pointer\n", arg);
                 return -EINVAL;
         }
 
         ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_type->name_off);
         if (!__btf_type_is_struct(t) || strcmp(ctx_tname, tname) != 0) {
                 bpf_log(log, "arg#%d should be `struct %s *`\n", arg, ctx_tname);
                 return -EINVAL;
         }
 
         return 0;
 }
 
 static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
                                      struct btf *btf,
                                      const struct btf_type *t,
                                      enum bpf_prog_type prog_type,
                                      int arg)
 {
         if (!btf_is_prog_ctx_type(log, btf, t, prog_type, arg))
                 return -ENOENT;
         return find_kern_ctx_type_id(prog_type);
 }
 
 int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type)
 {
         const struct btf_member *kctx_member;
         const struct btf_type *conv_struct;
         const struct btf_type *kctx_type;
         u32 kctx_type_id;
 
         conv_struct = bpf_ctx_convert.t;
         /* get member for kernel ctx type */
         kctx_member = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2 + 1;
         kctx_type_id = kctx_member->type;
         kctx_type = btf_type_by_id(btf_vmlinux, kctx_type_id);
         if (!btf_type_is_struct(kctx_type)) {
                 bpf_log(log, "kern ctx type id %u is not a struct\n", kctx_type_id);
                 return -EINVAL;
         }
 
         return kctx_type_id;
 }
 
 BTF_ID_LIST(bpf_ctx_convert_btf_id)
 BTF_ID(struct, bpf_ctx_convert)
 
 static struct btf *btf_parse_base(struct btf_verifier_env *env, const char *name,
                                   void *data, unsigned int data_size)
 {
         struct btf *btf = NULL;
         int err;
 
         if (!IS_ENABLED(CONFIG_DEBUG_INFO_BTF))
                 return ERR_PTR(-ENOENT);
 
         btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
         if (!btf) {
                 err = -ENOMEM;
                 goto errout;
         }
         env->btf = btf;
 
         btf->data = data;
         btf->data_size = data_size;
         btf->kernel_btf = true;
         snprintf(btf->name, sizeof(btf->name), "%s", name);
 
         err = btf_parse_hdr(env);
         if (err)
                 goto errout;
 
         btf->nohdr_data = btf->data + btf->hdr.hdr_len;
 
         err = btf_parse_str_sec(env);
         if (err)
                 goto errout;
 
         err = btf_check_all_metas(env);
         if (err)
                 goto errout;
 
         err = btf_check_type_tags(env, btf, 1);
         if (err)
                 goto errout;
 
         refcount_set(&btf->refcnt, 1);
 
         return btf;
 
 errout:
         if (btf) {
                 kvfree(btf->types);
                 kfree(btf);
         }
         return ERR_PTR(err);
 }
 
 struct btf *btf_parse_vmlinux(void)
 {
         struct btf_verifier_env *env = NULL;
         struct bpf_verifier_log *log;
         struct btf *btf;
         int err;
 
         env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
         if (!env)
                 return ERR_PTR(-ENOMEM);
 
         log = &env->log;
         log->level = BPF_LOG_KERNEL;
         btf = btf_parse_base(env, "vmlinux", __start_BTF, __stop_BTF - __start_BTF);
         if (IS_ERR(btf))
                 goto err_out;
 
         /* btf_parse_vmlinux() runs under bpf_verifier_lock */
         bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]);
         err = btf_alloc_id(btf);
         if (err) {
                 btf_free(btf);
                 btf = ERR_PTR(err);
         }
 err_out:
         btf_verifier_env_free(env);
         return btf;
 }
 
 /* If .BTF_ids section was created with distilled base BTF, both base and
  * split BTF ids will need to be mapped to actual base/split ids for
  * BTF now that it has been relocated.
  */
 static __u32 btf_relocate_id(const struct btf *btf, __u32 id)
 {
         if (!btf->base_btf || !btf->base_id_map)
                 return id;
         return btf->base_id_map[id];
 }
 
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 
 static struct btf *btf_parse_module(const char *module_name, const void *data,
                                     unsigned int data_size, void *base_data,
                                     unsigned int base_data_size)
 {
         struct btf *btf = NULL, *vmlinux_btf, *base_btf = NULL;
         struct btf_verifier_env *env = NULL;
         struct bpf_verifier_log *log;
         int err = 0;
 
         vmlinux_btf = bpf_get_btf_vmlinux();
         if (IS_ERR(vmlinux_btf))
                 return vmlinux_btf;
         if (!vmlinux_btf)
                 return ERR_PTR(-EINVAL);
 
         env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
         if (!env)
                 return ERR_PTR(-ENOMEM);
 
         log = &env->log;
         log->level = BPF_LOG_KERNEL;
 
         if (base_data) {
                 base_btf = btf_parse_base(env, ".BTF.base", base_data, base_data_size);
                 if (IS_ERR(base_btf)) {
                         err = PTR_ERR(base_btf);
                         goto errout;
                 }
         } else {
                 base_btf = vmlinux_btf;
         }
 
         btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
         if (!btf) {
                 err = -ENOMEM;
                 goto errout;
         }
         env->btf = btf;
 
         btf->base_btf = base_btf;
         btf->start_id = base_btf->nr_types;
         btf->start_str_off = base_btf->hdr.str_len;
         btf->kernel_btf = true;
         snprintf(btf->name, sizeof(btf->name), "%s", module_name);
 
         btf->data = kvmalloc(data_size, GFP_KERNEL | __GFP_NOWARN);
         if (!btf->data) {
                 err = -ENOMEM;
                 goto errout;
         }
         memcpy(btf->data, data, data_size);
         btf->data_size = data_size;
 
         err = btf_parse_hdr(env);
         if (err)
                 goto errout;
 
         btf->nohdr_data = btf->data + btf->hdr.hdr_len;
 
         err = btf_parse_str_sec(env);
         if (err)
                 goto errout;
 
         err = btf_check_all_metas(env);
         if (err)
                 goto errout;
 
         err = btf_check_type_tags(env, btf, btf_nr_types(base_btf));
         if (err)
                 goto errout;
 
         if (base_btf != vmlinux_btf) {
                 err = btf_relocate(btf, vmlinux_btf, &btf->base_id_map);
                 if (err)
                         goto errout;
                 btf_free(base_btf);
                 base_btf = vmlinux_btf;
         }
 
         btf_verifier_env_free(env);
         refcount_set(&btf->refcnt, 1);
         return btf;
 
 errout:
         btf_verifier_env_free(env);
         if (!IS_ERR(base_btf) && base_btf != vmlinux_btf)
                 btf_free(base_btf);
         if (btf) {
                 kvfree(btf->data);
                 kvfree(btf->types);
                 kfree(btf);
         }
         return ERR_PTR(err);
 }
 
 #endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
 
 struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog)
 {
         struct bpf_prog *tgt_prog = prog->aux->dst_prog;
 
         if (tgt_prog)
                 return tgt_prog->aux->btf;
         else
                 return prog->aux->attach_btf;
 }
 
 static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
 {
         /* skip modifiers */
         t = btf_type_skip_modifiers(btf, t->type, NULL);
 
         return btf_type_is_int(t);
 }
 
 static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto,
                            int off)
 {
         const struct btf_param *args;
         const struct btf_type *t;
         u32 offset = 0, nr_args;
         int i;
 
         if (!func_proto)
                 return off / 8;
 
         nr_args = btf_type_vlen(func_proto);
         args = (const struct btf_param *)(func_proto + 1);
         for (i = 0; i < nr_args; i++) {
                 t = btf_type_skip_modifiers(btf, args[i].type, NULL);
                 offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
                 if (off < offset)
                         return i;
         }
 
         t = btf_type_skip_modifiers(btf, func_proto->type, NULL);
         offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
         if (off < offset)
                 return nr_args;
 
         return nr_args + 1;
 }
 
 static bool prog_args_trusted(const struct bpf_prog *prog)
 {
         enum bpf_attach_type atype = prog->expected_attach_type;
 
         switch (prog->type) {
         case BPF_PROG_TYPE_TRACING:
                 return atype == BPF_TRACE_RAW_TP || atype == BPF_TRACE_ITER;
         case BPF_PROG_TYPE_LSM:
                 return bpf_lsm_is_trusted(prog);
         case BPF_PROG_TYPE_STRUCT_OPS:
                 return true;
         default:
                 return false;
         }
 }
 
 int btf_ctx_arg_offset(const struct btf *btf, const struct btf_type *func_proto,
                        u32 arg_no)
 {
         const struct btf_param *args;
         const struct btf_type *t;
         int off = 0, i;
         u32 sz;
 
         args = btf_params(func_proto);
         for (i = 0; i < arg_no; i++) {
                 t = btf_type_by_id(btf, args[i].type);
                 t = btf_resolve_size(btf, t, &sz);
                 if (IS_ERR(t))
                         return PTR_ERR(t);
                 off += roundup(sz, 8);
         }
 
         return off;
 }
 
 bool btf_ctx_access(int off, int size, enum bpf_access_type type,
                     const struct bpf_prog *prog,
                     struct bpf_insn_access_aux *info)
 {
         const struct btf_type *t = prog->aux->attach_func_proto;
         struct bpf_prog *tgt_prog = prog->aux->dst_prog;
         struct btf *btf = bpf_prog_get_target_btf(prog);
         const char *tname = prog->aux->attach_func_name;
         struct bpf_verifier_log *log = info->log;
         const struct btf_param *args;
         const char *tag_value;
         u32 nr_args, arg;
         int i, ret;
 
         if (off % 8) {
                 bpf_log(log, "func '%s' offset %d is not multiple of 8\n",
                         tname, off);
                 return false;
         }
         arg = get_ctx_arg_idx(btf, t, off);
         args = (const struct btf_param *)(t + 1);
         /* if (t == NULL) Fall back to default BPF prog with
          * MAX_BPF_FUNC_REG_ARGS u64 arguments.
          */
         nr_args = t ? btf_type_vlen(t) : MAX_BPF_FUNC_REG_ARGS;
         if (prog->aux->attach_btf_trace) {
                 /* skip first 'void *__data' argument in btf_trace_##name typedef */
                 args++;
                 nr_args--;
         }
 
         if (arg > nr_args) {
                 bpf_log(log, "func '%s' doesn't have %d-th argument\n",
                         tname, arg + 1);
                 return false;
         }
 
         if (arg == nr_args) {
                 switch (prog->expected_attach_type) {
                 case BPF_LSM_MAC:
                         /* mark we are accessing the return value */
                         info->is_retval = true;
                         fallthrough;
                 case BPF_LSM_CGROUP:
                 case BPF_TRACE_FEXIT:
                         /* When LSM programs are attached to void LSM hooks
                          * they use FEXIT trampolines and when attached to
                          * int LSM hooks, they use MODIFY_RETURN trampolines.
                          *
                          * While the LSM programs are BPF_MODIFY_RETURN-like
                          * the check:
                          *
                          *      if (ret_type != 'int')
                          *              return -EINVAL;
                          *
                          * is _not_ done here. This is still safe as LSM hooks
                          * have only void and int return types.
                          */
                         if (!t)
                                 return true;
                         t = btf_type_by_id(btf, t->type);
                         break;
                 case BPF_MODIFY_RETURN:
                         /* For now the BPF_MODIFY_RETURN can only be attached to
                          * functions that return an int.
                          */
                         if (!t)
                                 return false;
 
                         t = btf_type_skip_modifiers(btf, t->type, NULL);
                         if (!btf_type_is_small_int(t)) {
                                 bpf_log(log,
                                         "ret type %s not allowed for fmod_ret\n",
                                         btf_type_str(t));
                                 return false;
                         }
                         break;
                 default:
                         bpf_log(log, "func '%s' doesn't have %d-th argument\n",
                                 tname, arg + 1);
                         return false;
                 }
         } else {
                 if (!t)
                         /* Default prog with MAX_BPF_FUNC_REG_ARGS args */
                         return true;
                 t = btf_type_by_id(btf, args[arg].type);
         }
 
         /* skip modifiers */
         while (btf_type_is_modifier(t))
                 t = btf_type_by_id(btf, t->type);
         if (btf_type_is_small_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
                 /* accessing a scalar */
                 return true;
         if (!btf_type_is_ptr(t)) {
                 bpf_log(log,
                         "func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n",
                         tname, arg,
                         __btf_name_by_offset(btf, t->name_off),
                         btf_type_str(t));
                 return false;
         }
 
         /* check for PTR_TO_RDONLY_BUF_OR_NULL or PTR_TO_RDWR_BUF_OR_NULL */
         for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
                 const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
                 u32 type, flag;
 
                 type = base_type(ctx_arg_info->reg_type);
                 flag = type_flag(ctx_arg_info->reg_type);
                 if (ctx_arg_info->offset == off && type == PTR_TO_BUF &&
                     (flag & PTR_MAYBE_NULL)) {
                         info->reg_type = ctx_arg_info->reg_type;
                         return true;
                 }
         }
 
         if (t->type == 0)
                 /* This is a pointer to void.
                  * It is the same as scalar from the verifier safety pov.
                  * No further pointer walking is allowed.
                  */
                 return true;
 
         if (is_int_ptr(btf, t))
                 return true;
 
         /* this is a pointer to another type */
         for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
                 const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
 
                 if (ctx_arg_info->offset == off) {
                         if (!ctx_arg_info->btf_id) {
                                 bpf_log(log,"invalid btf_id for context argument offset %u\n", off);
                                 return false;
                         }
 
                         info->reg_type = ctx_arg_info->reg_type;
                         info->btf = ctx_arg_info->btf ? : btf_vmlinux;
                         info->btf_id = ctx_arg_info->btf_id;
                         return true;
                 }
         }
 
         info->reg_type = PTR_TO_BTF_ID;
         if (prog_args_trusted(prog))
                 info->reg_type |= PTR_TRUSTED;
 
         if (tgt_prog) {
                 enum bpf_prog_type tgt_type;
 
                 if (tgt_prog->type == BPF_PROG_TYPE_EXT)
                         tgt_type = tgt_prog->aux->saved_dst_prog_type;
                 else
                         tgt_type = tgt_prog->type;
 
                 ret = btf_translate_to_vmlinux(log, btf, t, tgt_type, arg);
                 if (ret > 0) {
                         info->btf = btf_vmlinux;
                         info->btf_id = ret;
                         return true;
                 } else {
                         return false;
                 }
         }
 
         info->btf = btf;
         info->btf_id = t->type;
         t = btf_type_by_id(btf, t->type);
 
         if (btf_type_is_type_tag(t)) {
                 tag_value = __btf_name_by_offset(btf, t->name_off);
                 if (strcmp(tag_value, "user") == 0)
                         info->reg_type |= MEM_USER;
                 if (strcmp(tag_value, "percpu") == 0)
                         info->reg_type |= MEM_PERCPU;
         }
 
         /* skip modifiers */
         while (btf_type_is_modifier(t)) {
                 info->btf_id = t->type;
                 t = btf_type_by_id(btf, t->type);
         }
         if (!btf_type_is_struct(t)) {
                 bpf_log(log,
                         "func '%s' arg%d type %s is not a struct\n",
                         tname, arg, btf_type_str(t));
                 return false;
         }
         bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n",
                 tname, arg, info->btf_id, btf_type_str(t),
                 __btf_name_by_offset(btf, t->name_off));
         return true;
 }
 EXPORT_SYMBOL_GPL(btf_ctx_access);
 
 enum bpf_struct_walk_result {
         /* < 0 error */
         WALK_SCALAR = 0,
         WALK_PTR,
         WALK_STRUCT,
 };
 
 static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf,
                            const struct btf_type *t, int off, int size,
                            u32 *next_btf_id, enum bpf_type_flag *flag,
                            const char **field_name)
 {
         u32 i, moff, mtrue_end, msize = 0, total_nelems = 0;
         const struct btf_type *mtype, *elem_type = NULL;
         const struct btf_member *member;
         const char *tname, *mname, *tag_value;
         u32 vlen, elem_id, mid;
 
 again:
         if (btf_type_is_modifier(t))
                 t = btf_type_skip_modifiers(btf, t->type, NULL);
         tname = __btf_name_by_offset(btf, t->name_off);
         if (!btf_type_is_struct(t)) {
                 bpf_log(log, "Type '%s' is not a struct\n", tname);
                 return -EINVAL;
         }
 
         vlen = btf_type_vlen(t);
         if (BTF_INFO_KIND(t->info) == BTF_KIND_UNION && vlen != 1 && !(*flag & PTR_UNTRUSTED))
                 /*
                  * walking unions yields untrusted pointers
                  * with exception of __bpf_md_ptr and other
                  * unions with a single member
                  */
                 *flag |= PTR_UNTRUSTED;
 
         if (off + size > t->size) {
                 /* If the last element is a variable size array, we may
                  * need to relax the rule.
                  */
                 struct btf_array *array_elem;
 
                 if (vlen == 0)
                         goto error;
 
                 member = btf_type_member(t) + vlen - 1;
                 mtype = btf_type_skip_modifiers(btf, member->type,
                                                 NULL);
                 if (!btf_type_is_array(mtype))
                         goto error;
 
                 array_elem = (struct btf_array *)(mtype + 1);
                 if (array_elem->nelems != 0)
                         goto error;
 
                 moff = __btf_member_bit_offset(t, member) / 8;
                 if (off < moff)
                         goto error;
 
                 /* allow structure and integer */
                 t = btf_type_skip_modifiers(btf, array_elem->type,
                                             NULL);
 
                 if (btf_type_is_int(t))
                         return WALK_SCALAR;
 
                 if (!btf_type_is_struct(t))
                         goto error;
 
                 off = (off - moff) % t->size;
                 goto again;
 
 error:
                 bpf_log(log, "access beyond struct %s at off %u size %u\n",
                         tname, off, size);
                 return -EACCES;
         }
 
         for_each_member(i, t, member) {
                 /* offset of the field in bytes */
                 moff = __btf_member_bit_offset(t, member) / 8;
                 if (off + size <= moff)
                         /* won't find anything, field is already too far */
                         break;
 
                 if (__btf_member_bitfield_size(t, member)) {
                         u32 end_bit = __btf_member_bit_offset(t, member) +
                                 __btf_member_bitfield_size(t, member);
 
                         /* off <= moff instead of off == moff because clang
                          * does not generate a BTF member for anonymous
                          * bitfield like the ":16" here:
                          * struct {
                          *      int :16;
                          *      int x:8;
                          * };
                          */
                         if (off <= moff &&
                             BITS_ROUNDUP_BYTES(end_bit) <= off + size)
                                 return WALK_SCALAR;
 
                         /* off may be accessing a following member
                          *
                          * or
                          *
                          * Doing partial access at either end of this
                          * bitfield.  Continue on this case also to
                          * treat it as not accessing this bitfield
                          * and eventually error out as field not
                          * found to keep it simple.
                          * It could be relaxed if there was a legit
                          * partial access case later.
                          */
                         continue;
                 }
 
                 /* In case of "off" is pointing to holes of a struct */
                 if (off < moff)
                         break;
 
                 /* type of the field */
                 mid = member->type;
                 mtype = btf_type_by_id(btf, member->type);
                 mname = __btf_name_by_offset(btf, member->name_off);
 
                 mtype = __btf_resolve_size(btf, mtype, &msize,
                                            &elem_type, &elem_id, &total_nelems,
                                            &mid);
                 if (IS_ERR(mtype)) {
                         bpf_log(log, "field %s doesn't have size\n", mname);
                         return -EFAULT;
                 }
 
                 mtrue_end = moff + msize;
                 if (off >= mtrue_end)
                         /* no overlap with member, keep iterating */
                         continue;
 
                 if (btf_type_is_array(mtype)) {
                         u32 elem_idx;
 
                         /* __btf_resolve_size() above helps to
                          * linearize a multi-dimensional array.
                          *
                          * The logic here is treating an array
                          * in a struct as the following way:
                          *
                          * struct outer {
                          *      struct inner array[2][2];
                          * };
                          *
                          * looks like:
                          *
                          * struct outer {
                          *      struct inner array_elem0;
                          *      struct inner array_elem1;
                          *      struct inner array_elem2;
                          *      struct inner array_elem3;
                          * };
                          *
                          * When accessing outer->array[1][0], it moves
                          * moff to "array_elem2", set mtype to
                          * "struct inner", and msize also becomes
                          * sizeof(struct inner).  Then most of the
                          * remaining logic will fall through without
                          * caring the current member is an array or
                          * not.
                          *
                          * Unlike mtype/msize/moff, mtrue_end does not
                          * change.  The naming difference ("_true") tells
                          * that it is not always corresponding to
                          * the current mtype/msize/moff.
                          * It is the true end of the current
                          * member (i.e. array in this case).  That
                          * will allow an int array to be accessed like
                          * a scratch space,
                          * i.e. allow access beyond the size of
                          *      the array's element as long as it is
                          *      within the mtrue_end boundary.
                          */
 
                         /* skip empty array */
                         if (moff == mtrue_end)
                                 continue;
 
                         msize /= total_nelems;
                         elem_idx = (off - moff) / msize;
                         moff += elem_idx * msize;
                         mtype = elem_type;
                         mid = elem_id;
                 }
 
                 /* the 'off' we're looking for is either equal to start
                  * of this field or inside of this struct
                  */
                 if (btf_type_is_struct(mtype)) {
                         /* our field must be inside that union or struct */
                         t = mtype;
 
                         /* return if the offset matches the member offset */
                         if (off == moff) {
                                 *next_btf_id = mid;
                                 return WALK_STRUCT;
                         }
 
                         /* adjust offset we're looking for */
                         off -= moff;
                         goto again;
                 }
 
                 if (btf_type_is_ptr(mtype)) {
                         const struct btf_type *stype, *t;
                         enum bpf_type_flag tmp_flag = 0;
                         u32 id;
 
                         if (msize != size || off != moff) {
                                 bpf_log(log,
                                         "cannot access ptr member %s with moff %u in struct %s with off %u size %u\n",
                                         mname, moff, tname, off, size);
                                 return -EACCES;
                         }
 
                         /* check type tag */
                         t = btf_type_by_id(btf, mtype->type);
                         if (btf_type_is_type_tag(t)) {
                                 tag_value = __btf_name_by_offset(btf, t->name_off);
                                 /* check __user tag */
                                 if (strcmp(tag_value, "user") == 0)
                                         tmp_flag = MEM_USER;
                                 /* check __percpu tag */
                                 if (strcmp(tag_value, "percpu") == 0)
                                         tmp_flag = MEM_PERCPU;
                                 /* check __rcu tag */
                                 if (strcmp(tag_value, "rcu") == 0)
                                         tmp_flag = MEM_RCU;
                         }
 
                         stype = btf_type_skip_modifiers(btf, mtype->type, &id);
                         if (btf_type_is_struct(stype)) {
                                 *next_btf_id = id;
                                 *flag |= tmp_flag;
                                 if (field_name)
                                         *field_name = mname;
                                 return WALK_PTR;
                         }
                 }
 
                 /* Allow more flexible access within an int as long as
                  * it is within mtrue_end.
                  * Since mtrue_end could be the end of an array,
                  * that also allows using an array of int as a scratch
                  * space. e.g. skb->cb[].
                  */
                 if (off + size > mtrue_end && !(*flag & PTR_UNTRUSTED)) {
                         bpf_log(log,
                                 "access beyond the end of member %s (mend:%u) in struct %s with off %u size %u\n",
                                 mname, mtrue_end, tname, off, size);
                         return -EACCES;
                 }
 
                 return WALK_SCALAR;
         }
         bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
         return -EINVAL;
 }
 
 int btf_struct_access(struct bpf_verifier_log *log,
                       const struct bpf_reg_state *reg,
                       int off, int size, enum bpf_access_type atype __maybe_unused,
                       u32 *next_btf_id, enum bpf_type_flag *flag,
                       const char **field_name)
 {
         const struct btf *btf = reg->btf;
         enum bpf_type_flag tmp_flag = 0;
         const struct btf_type *t;
         u32 id = reg->btf_id;
         int err;
 
         while (type_is_alloc(reg->type)) {
                 struct btf_struct_meta *meta;
                 struct btf_record *rec;
                 int i;
 
                 meta = btf_find_struct_meta(btf, id);
                 if (!meta)
                         break;
                 rec = meta->record;
                 for (i = 0; i < rec->cnt; i++) {
                         struct btf_field *field = &rec->fields[i];
                         u32 offset = field->offset;
                         if (off < offset + field->size && offset < off + size) {
                                 bpf_log(log,
                                         "direct access to %s is disallowed\n",
                                         btf_field_type_name(field->type));
                                 return -EACCES;
                         }
                 }
                 break;
         }
 
         t = btf_type_by_id(btf, id);
         do {
                 err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag, field_name);
 
                 switch (err) {
                 case WALK_PTR:
                         /* For local types, the destination register cannot
                          * become a pointer again.
                          */
                         if (type_is_alloc(reg->type))
                                 return SCALAR_VALUE;
                         /* If we found the pointer or scalar on t+off,
                          * we're done.
                          */
                         *next_btf_id = id;
                         *flag = tmp_flag;
                         return PTR_TO_BTF_ID;
                 case WALK_SCALAR:
                         return SCALAR_VALUE;
                 case WALK_STRUCT:
                         /* We found nested struct, so continue the search
                          * by diving in it. At this point the offset is
                          * aligned with the new type, so set it to 0.
                          */
                         t = btf_type_by_id(btf, id);
                         off = 0;
                         break;
                 default:
                         /* It's either error or unknown return value..
                          * scream and leave.
                          */
                         if (WARN_ONCE(err > 0, "unknown btf_struct_walk return value"))
                                 return -EINVAL;
                         return err;
                 }
         } while (t);
 
         return -EINVAL;
 }
 
 /* Check that two BTF types, each specified as an BTF object + id, are exactly
  * the same. Trivial ID check is not enough due to module BTFs, because we can
  * end up with two different module BTFs, but IDs point to the common type in
  * vmlinux BTF.
  */
 bool btf_types_are_same(const struct btf *btf1, u32 id1,
                         const struct btf *btf2, u32 id2)
 {
         if (id1 != id2)
                 return false;
         if (btf1 == btf2)
                 return true;
         return btf_type_by_id(btf1, id1) == btf_type_by_id(btf2, id2);
 }
 
 bool btf_struct_ids_match(struct bpf_verifier_log *log,
                           const struct btf *btf, u32 id, int off,
                           const struct btf *need_btf, u32 need_type_id,
                           bool strict)
 {
         const struct btf_type *type;
         enum bpf_type_flag flag = 0;
         int err;
 
         /* Are we already done? */
         if (off == 0 && btf_types_are_same(btf, id, need_btf, need_type_id))
                 return true;
         /* In case of strict type match, we do not walk struct, the top level
          * type match must succeed. When strict is true, off should have already
          * been 0.
          */
         if (strict)
                 return false;
 again:
         type = btf_type_by_id(btf, id);
         if (!type)
                 return false;
         err = btf_struct_walk(log, btf, type, off, 1, &id, &flag, NULL);
         if (err != WALK_STRUCT)
                 return false;
 
         /* We found nested struct object. If it matches
          * the requested ID, we're done. Otherwise let's
          * continue the search with offset 0 in the new
          * type.
          */
         if (!btf_types_are_same(btf, id, need_btf, need_type_id)) {
                 off = 0;
                 goto again;
         }
 
         return true;
 }
 
 static int __get_type_size(struct btf *btf, u32 btf_id,
                            const struct btf_type **ret_type)
 {
         const struct btf_type *t;
 
         *ret_type = btf_type_by_id(btf, 0);
         if (!btf_id)
                 /* void */
                 return 0;
         t = btf_type_by_id(btf, btf_id);
         while (t && btf_type_is_modifier(t))
                 t = btf_type_by_id(btf, t->type);
         if (!t)
                 return -EINVAL;
         *ret_type = t;
         if (btf_type_is_ptr(t))
                 /* kernel size of pointer. Not BPF's size of pointer*/
                 return sizeof(void *);
         if (btf_type_is_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
                 return t->size;
         return -EINVAL;
 }
 
 static u8 __get_type_fmodel_flags(const struct btf_type *t)
 {
         u8 flags = 0;
 
         if (__btf_type_is_struct(t))
                 flags |= BTF_FMODEL_STRUCT_ARG;
         if (btf_type_is_signed_int(t))
                 flags |= BTF_FMODEL_SIGNED_ARG;
 
         return flags;
 }
 
 int btf_distill_func_proto(struct bpf_verifier_log *log,
                            struct btf *btf,
                            const struct btf_type *func,
                            const char *tname,
                            struct btf_func_model *m)
 {
         const struct btf_param *args;
         const struct btf_type *t;
         u32 i, nargs;
         int ret;
 
         if (!func) {
                 /* BTF function prototype doesn't match the verifier types.
                  * Fall back to MAX_BPF_FUNC_REG_ARGS u64 args.
                  */
                 for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
                         m->arg_size[i] = 8;
                         m->arg_flags[i] = 0;
                 }
                 m->ret_size = 8;
                 m->ret_flags = 0;
                 m->nr_args = MAX_BPF_FUNC_REG_ARGS;
                 return 0;
         }
         args = (const struct btf_param *)(func + 1);
         nargs = btf_type_vlen(func);
         if (nargs > MAX_BPF_FUNC_ARGS) {
                 bpf_log(log,
                         "The function %s has %d arguments. Too many.\n",
                         tname, nargs);
                 return -EINVAL;
         }
         ret = __get_type_size(btf, func->type, &t);
         if (ret < 0 || __btf_type_is_struct(t)) {
                 bpf_log(log,
                         "The function %s return type %s is unsupported.\n",
                         tname, btf_type_str(t));
                 return -EINVAL;
         }
         m->ret_size = ret;
         m->ret_flags = __get_type_fmodel_flags(t);
 
         for (i = 0; i < nargs; i++) {
                 if (i == nargs - 1 && args[i].type == 0) {
                         bpf_log(log,
                                 "The function %s with variable args is unsupported.\n",
                                 tname);
                         return -EINVAL;
                 }
                 ret = __get_type_size(btf, args[i].type, &t);
 
                 /* No support of struct argument size greater than 16 bytes */
                 if (ret < 0 || ret > 16) {
                         bpf_log(log,
                                 "The function %s arg%d type %s is unsupported.\n",
                                 tname, i, btf_type_str(t));
                         return -EINVAL;
                 }
                 if (ret == 0) {
                         bpf_log(log,
                                 "The function %s has malformed void argument.\n",
                                 tname);
                         return -EINVAL;
                 }
                 m->arg_size[i] = ret;
                 m->arg_flags[i] = __get_type_fmodel_flags(t);
         }
         m->nr_args = nargs;
         return 0;
 }
 
 /* Compare BTFs of two functions assuming only scalars and pointers to context.
  * t1 points to BTF_KIND_FUNC in btf1
  * t2 points to BTF_KIND_FUNC in btf2
  * Returns:
  * EINVAL - function prototype mismatch
  * EFAULT - verifier bug
  * 0 - 99% match. The last 1% is validated by the verifier.
  */
 static int btf_check_func_type_match(struct bpf_verifier_log *log,
                                      struct btf *btf1, const struct btf_type *t1,
                                      struct btf *btf2, const struct btf_type *t2)
 {
         const struct btf_param *args1, *args2;
         const char *fn1, *fn2, *s1, *s2;
         u32 nargs1, nargs2, i;
 
         fn1 = btf_name_by_offset(btf1, t1->name_off);
         fn2 = btf_name_by_offset(btf2, t2->name_off);
 
         if (btf_func_linkage(t1) != BTF_FUNC_GLOBAL) {
                 bpf_log(log, "%s() is not a global function\n", fn1);
                 return -EINVAL;
         }
         if (btf_func_linkage(t2) != BTF_FUNC_GLOBAL) {
                 bpf_log(log, "%s() is not a global function\n", fn2);
                 return -EINVAL;
         }
 
         t1 = btf_type_by_id(btf1, t1->type);
         if (!t1 || !btf_type_is_func_proto(t1))
                 return -EFAULT;
         t2 = btf_type_by_id(btf2, t2->type);
         if (!t2 || !btf_type_is_func_proto(t2))
                 return -EFAULT;
 
         args1 = (const struct btf_param *)(t1 + 1);
         nargs1 = btf_type_vlen(t1);
         args2 = (const struct btf_param *)(t2 + 1);
         nargs2 = btf_type_vlen(t2);
 
         if (nargs1 != nargs2) {
                 bpf_log(log, "%s() has %d args while %s() has %d args\n",
                         fn1, nargs1, fn2, nargs2);
                 return -EINVAL;
         }
 
         t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
         t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
         if (t1->info != t2->info) {
                 bpf_log(log,
                         "Return type %s of %s() doesn't match type %s of %s()\n",
                         btf_type_str(t1), fn1,
                         btf_type_str(t2), fn2);
                 return -EINVAL;
         }
 
         for (i = 0; i < nargs1; i++) {
                 t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
                 t2 = btf_type_skip_modifiers(btf2, args2[i].type, NULL);
 
                 if (t1->info != t2->info) {
                         bpf_log(log, "arg%d in %s() is %s while %s() has %s\n",
                                 i, fn1, btf_type_str(t1),
                                 fn2, btf_type_str(t2));
                         return -EINVAL;
                 }
                 if (btf_type_has_size(t1) && t1->size != t2->size) {
                         bpf_log(log,
                                 "arg%d in %s() has size %d while %s() has %d\n",
                                 i, fn1, t1->size,
                                 fn2, t2->size);
                         return -EINVAL;
                 }
 
                 /* global functions are validated with scalars and pointers
                  * to context only. And only global functions can be replaced.
                  * Hence type check only those types.
                  */
                 if (btf_type_is_int(t1) || btf_is_any_enum(t1))
                         continue;
                 if (!btf_type_is_ptr(t1)) {
                         bpf_log(log,
                                 "arg%d in %s() has unrecognized type\n",
                                 i, fn1);
                         return -EINVAL;
                 }
                 t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
                 t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
                 if (!btf_type_is_struct(t1)) {
                         bpf_log(log,
                                 "arg%d in %s() is not a pointer to context\n",
                                 i, fn1);
                         return -EINVAL;
                 }
                 if (!btf_type_is_struct(t2)) {
                         bpf_log(log,
                                 "arg%d in %s() is not a pointer to context\n",
                                 i, fn2);
                         return -EINVAL;
                 }
                 /* This is an optional check to make program writing easier.
                  * Compare names of structs and report an error to the user.
                  * btf_prepare_func_args() already checked that t2 struct
                  * is a context type. btf_prepare_func_args() will check
                  * later that t1 struct is a context type as well.
                  */
                 s1 = btf_name_by_offset(btf1, t1->name_off);
                 s2 = btf_name_by_offset(btf2, t2->name_off);
                 if (strcmp(s1, s2)) {
                         bpf_log(log,
                                 "arg%d %s(struct %s *) doesn't match %s(struct %s *)\n",
                                 i, fn1, s1, fn2, s2);
                         return -EINVAL;
                 }
         }
         return 0;
 }
 
 /* Compare BTFs of given program with BTF of target program */
 int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
                          struct btf *btf2, const struct btf_type *t2)
 {
         struct btf *btf1 = prog->aux->btf;
         const struct btf_type *t1;
         u32 btf_id = 0;
 
         if (!prog->aux->func_info) {
                 bpf_log(log, "Program extension requires BTF\n");
                 return -EINVAL;
         }
 
         btf_id = prog->aux->func_info[0].type_id;
         if (!btf_id)
                 return -EFAULT;
 
         t1 = btf_type_by_id(btf1, btf_id);
         if (!t1 || !btf_type_is_func(t1))
                 return -EFAULT;
 
         return btf_check_func_type_match(log, btf1, t1, btf2, t2);
 }
 
 static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t)
 {
         const char *name;
 
         t = btf_type_by_id(btf, t->type); /* skip PTR */
 
         while (btf_type_is_modifier(t))
                 t = btf_type_by_id(btf, t->type);
 
         /* allow either struct or struct forward declaration */
         if (btf_type_is_struct(t) ||
             (btf_type_is_fwd(t) && btf_type_kflag(t) == 0)) {
                 name = btf_str_by_offset(btf, t->name_off);
                 return name && strcmp(name, "bpf_dynptr") == 0;
         }
 
         return false;
 }
 
 struct bpf_cand_cache {
         const char *name;
         u32 name_len;
         u16 kind;
         u16 cnt;
         struct {
                 const struct btf *btf;
                 u32 id;
         } cands[];
 };
 
 static DEFINE_MUTEX(cand_cache_mutex);
 
 static struct bpf_cand_cache *
 bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id);
 
 static int btf_get_ptr_to_btf_id(struct bpf_verifier_log *log, int arg_idx,
                                  const struct btf *btf, const struct btf_type *t)
 {
         struct bpf_cand_cache *cc;
         struct bpf_core_ctx ctx = {
                 .btf = btf,
                 .log = log,
         };
         u32 kern_type_id, type_id;
         int err = 0;
 
         /* skip PTR and modifiers */
         type_id = t->type;
         t = btf_type_by_id(btf, t->type);
         while (btf_type_is_modifier(t)) {
                 type_id = t->type;
                 t = btf_type_by_id(btf, t->type);
         }
 
         mutex_lock(&cand_cache_mutex);
         cc = bpf_core_find_cands(&ctx, type_id);
         if (IS_ERR(cc)) {
                 err = PTR_ERR(cc);
                 bpf_log(log, "arg#%d reference type('%s %s') candidate matching error: %d\n",
                         arg_idx, btf_type_str(t), __btf_name_by_offset(btf, t->name_off),
                         err);
                 goto cand_cache_unlock;
         }
         if (cc->cnt != 1) {
                 bpf_log(log, "arg#%d reference type('%s %s') %s\n",
                         arg_idx, btf_type_str(t), __btf_name_by_offset(btf, t->name_off),
                         cc->cnt == 0 ? "has no matches" : "is ambiguous");
                 err = cc->cnt == 0 ? -ENOENT : -ESRCH;
                 goto cand_cache_unlock;
         }
         if (btf_is_module(cc->cands[0].btf)) {
                 bpf_log(log, "arg#%d reference type('%s %s') points to kernel module type (unsupported)\n",
                         arg_idx, btf_type_str(t), __btf_name_by_offset(btf, t->name_off));
                 err = -EOPNOTSUPP;
                 goto cand_cache_unlock;
         }
         kern_type_id = cc->cands[0].id;
 
 cand_cache_unlock:
         mutex_unlock(&cand_cache_mutex);
         if (err)
                 return err;
 
         return kern_type_id;
 }
 
 enum btf_arg_tag {
         ARG_TAG_CTX      = BIT_ULL(0),
         ARG_TAG_NONNULL  = BIT_ULL(1),
         ARG_TAG_TRUSTED  = BIT_ULL(2),
         ARG_TAG_NULLABLE = BIT_ULL(3),
         ARG_TAG_ARENA    = BIT_ULL(4),
 };
 
 /* Process BTF of a function to produce high-level expectation of function
  * arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information
  * is cached in subprog info for reuse.
  * Returns:
  * EFAULT - there is a verifier bug. Abort verification.
  * EINVAL - cannot convert BTF.
  * 0 - Successfully processed BTF and constructed argument expectations.
  */
 int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
 {
         bool is_global = subprog_aux(env, subprog)->linkage == BTF_FUNC_GLOBAL;
         struct bpf_subprog_info *sub = subprog_info(env, subprog);
         struct bpf_verifier_log *log = &env->log;
         struct bpf_prog *prog = env->prog;
         enum bpf_prog_type prog_type = prog->type;
         struct btf *btf = prog->aux->btf;
         const struct btf_param *args;
         const struct btf_type *t, *ref_t, *fn_t;
         u32 i, nargs, btf_id;
         const char *tname;
 
         if (sub->args_cached)
                 return 0;
 
         if (!prog->aux->func_info) {
                 bpf_log(log, "Verifier bug\n");
                 return -EFAULT;
         }
 
         btf_id = prog->aux->func_info[subprog].type_id;
         if (!btf_id) {
                 if (!is_global) /* not fatal for static funcs */
                         return -EINVAL;
                 bpf_log(log, "Global functions need valid BTF\n");
                 return -EFAULT;
         }
 
         fn_t = btf_type_by_id(btf, btf_id);
         if (!fn_t || !btf_type_is_func(fn_t)) {
                 /* These checks were already done by the verifier while loading
                  * struct bpf_func_info
                  */
                 bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
                         subprog);
                 return -EFAULT;
         }
         tname = btf_name_by_offset(btf, fn_t->name_off);
 
         if (prog->aux->func_info_aux[subprog].unreliable) {
                 bpf_log(log, "Verifier bug in function %s()\n", tname);
                 return -EFAULT;
         }
         if (prog_type == BPF_PROG_TYPE_EXT)
                 prog_type = prog->aux->dst_prog->type;
 
         t = btf_type_by_id(btf, fn_t->type);
         if (!t || !btf_type_is_func_proto(t)) {
                 bpf_log(log, "Invalid type of function %s()\n", tname);
                 return -EFAULT;
         }
         args = (const struct btf_param *)(t + 1);
         nargs = btf_type_vlen(t);
         if (nargs > MAX_BPF_FUNC_REG_ARGS) {
                 if (!is_global)
                         return -EINVAL;
                 bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
                         tname, nargs, MAX_BPF_FUNC_REG_ARGS);
                 return -EINVAL;
         }
         /* check that function returns int, exception cb also requires this */
         t = btf_type_by_id(btf, t->type);
         while (btf_type_is_modifier(t))
                 t = btf_type_by_id(btf, t->type);
         if (!btf_type_is_int(t) && !btf_is_any_enum(t)) {
                 if (!is_global)
                         return -EINVAL;
                 bpf_log(log,
                         "Global function %s() doesn't return scalar. Only those are supported.\n",
                         tname);
                 return -EINVAL;
         }
         /* Convert BTF function arguments into verifier types.
          * Only PTR_TO_CTX and SCALAR are supported atm.
          */
         for (i = 0; i < nargs; i++) {
                 u32 tags = 0;
                 int id = 0;
 
                 /* 'arg:<tag>' decl_tag takes precedence over derivation of
                  * register type from BTF type itself
                  */
                 while ((id = btf_find_next_decl_tag(btf, fn_t, i, "arg:", id)) > 0) {
                         const struct btf_type *tag_t = btf_type_by_id(btf, id);
                         const char *tag = __btf_name_by_offset(btf, tag_t->name_off) + 4;
 
                         /* disallow arg tags in static subprogs */
                         if (!is_global) {
                                 bpf_log(log, "arg#%d type tag is not supported in static functions\n", i);
                                 return -EOPNOTSUPP;
                         }
 
                         if (strcmp(tag, "ctx") == 0) {
                                 tags |= ARG_TAG_CTX;
                         } else if (strcmp(tag, "trusted") == 0) {
                                 tags |= ARG_TAG_TRUSTED;
                         } else if (strcmp(tag, "nonnull") == 0) {
                                 tags |= ARG_TAG_NONNULL;
                         } else if (strcmp(tag, "nullable") == 0) {
                                 tags |= ARG_TAG_NULLABLE;
                         } else if (strcmp(tag, "arena") == 0) {
                                 tags |= ARG_TAG_ARENA;
                         } else {
                                 bpf_log(log, "arg#%d has unsupported set of tags\n", i);
                                 return -EOPNOTSUPP;
                         }
                 }
                 if (id != -ENOENT) {
                         bpf_log(log, "arg#%d type tag fetching failure: %d\n", i, id);
                         return id;
                 }
 
                 t = btf_type_by_id(btf, args[i].type);
                 while (btf_type_is_modifier(t))
                         t = btf_type_by_id(btf, t->type);
                 if (!btf_type_is_ptr(t))
                         goto skip_pointer;
 
                 if ((tags & ARG_TAG_CTX) || btf_is_prog_ctx_type(log, btf, t, prog_type, i)) {
                         if (tags & ~ARG_TAG_CTX) {
                                 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
                                 return -EINVAL;
                         }
                         if ((tags & ARG_TAG_CTX) &&
                             btf_validate_prog_ctx_type(log, btf, t, i, prog_type,
                                                        prog->expected_attach_type))
                                 return -EINVAL;
                         sub->args[i].arg_type = ARG_PTR_TO_CTX;
                         continue;
                 }
                 if (btf_is_dynptr_ptr(btf, t)) {
                         if (tags) {
                                 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
                                 return -EINVAL;
                         }
                         sub->args[i].arg_type = ARG_PTR_TO_DYNPTR | MEM_RDONLY;
                         continue;
                 }
                 if (tags & ARG_TAG_TRUSTED) {
                         int kern_type_id;
 
                         if (tags & ARG_TAG_NONNULL) {
                                 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
                                 return -EINVAL;
                         }
 
                         kern_type_id = btf_get_ptr_to_btf_id(log, i, btf, t);
                         if (kern_type_id < 0)
                                 return kern_type_id;
 
                         sub->args[i].arg_type = ARG_PTR_TO_BTF_ID | PTR_TRUSTED;
                         if (tags & ARG_TAG_NULLABLE)
                                 sub->args[i].arg_type |= PTR_MAYBE_NULL;
                         sub->args[i].btf_id = kern_type_id;
                         continue;
                 }
                 if (tags & ARG_TAG_ARENA) {
                         if (tags & ~ARG_TAG_ARENA) {
                                 bpf_log(log, "arg#%d arena cannot be combined with any other tags\n", i);
                                 return -EINVAL;
                         }
                         sub->args[i].arg_type = ARG_PTR_TO_ARENA;
                         continue;
                 }
                 if (is_global) { /* generic user data pointer */
                         u32 mem_size;
 
                         if (tags & ARG_TAG_NULLABLE) {
                                 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
                                 return -EINVAL;
                         }
 
                         t = btf_type_skip_modifiers(btf, t->type, NULL);
                         ref_t = btf_resolve_size(btf, t, &mem_size);
                         if (IS_ERR(ref_t)) {
                                 bpf_log(log, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
                                         i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
                                         PTR_ERR(ref_t));
                                 return -EINVAL;
                         }
 
                         sub->args[i].arg_type = ARG_PTR_TO_MEM | PTR_MAYBE_NULL;
                         if (tags & ARG_TAG_NONNULL)
                                 sub->args[i].arg_type &= ~PTR_MAYBE_NULL;
                         sub->args[i].mem_size = mem_size;
                         continue;
                 }
 
 skip_pointer:
                 if (tags) {
                         bpf_log(log, "arg#%d has pointer tag, but is not a pointer type\n", i);
                         return -EINVAL;
                 }
                 if (btf_type_is_int(t) || btf_is_any_enum(t)) {
                         sub->args[i].arg_type = ARG_ANYTHING;
                         continue;
                 }
                 if (!is_global)
                         return -EINVAL;
                 bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
                         i, btf_type_str(t), tname);
                 return -EINVAL;
         }
 
         sub->arg_cnt = nargs;
         sub->args_cached = true;
 
         return 0;
 }
 
 static void btf_type_show(const struct btf *btf, u32 type_id, void *obj,
                           struct btf_show *show)
 {
         const struct btf_type *t = btf_type_by_id(btf, type_id);
 
         show->btf = btf;
         memset(&show->state, 0, sizeof(show->state));
         memset(&show->obj, 0, sizeof(show->obj));
 
         btf_type_ops(t)->show(btf, t, type_id, obj, 0, show);
 }
 
 __printf(2, 0) static void btf_seq_show(struct btf_show *show, const char *fmt,
                                         va_list args)
 {
         seq_vprintf((struct seq_file *)show->target, fmt, args);
 }
 
 int btf_type_seq_show_flags(const struct btf *btf, u32 type_id,
                             void *obj, struct seq_file *m, u64 flags)
 {
         struct btf_show sseq;
 
         sseq.target = m;
         sseq.showfn = btf_seq_show;
         sseq.flags = flags;
 
         btf_type_show(btf, type_id, obj, &sseq);
 
         return sseq.state.status;
 }
 
 void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
                        struct seq_file *m)
 {
         (void) btf_type_seq_show_flags(btf, type_id, obj, m,
                                        BTF_SHOW_NONAME | BTF_SHOW_COMPACT |
                                        BTF_SHOW_ZERO | BTF_SHOW_UNSAFE);
 }
 
 struct btf_show_snprintf {
         struct btf_show show;
         int len_left;           /* space left in string */
         int len;                /* length we would have written */
 };
 
 __printf(2, 0) static void btf_snprintf_show(struct btf_show *show, const char *fmt,
                                              va_list args)
 {
         struct btf_show_snprintf *ssnprintf = (struct btf_show_snprintf *)show;
         int len;
 
         len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
 
         if (len < 0) {
                 ssnprintf->len_left = 0;
                 ssnprintf->len = len;
         } else if (len >= ssnprintf->len_left) {
                 /* no space, drive on to get length we would have written */
                 ssnprintf->len_left = 0;
                 ssnprintf->len += len;
         } else {
                 ssnprintf->len_left -= len;
                 ssnprintf->len += len;
                 show->target += len;
         }
 }
 
 int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
                            char *buf, int len, u64 flags)
 {
         struct btf_show_snprintf ssnprintf;
 
         ssnprintf.show.target = buf;
         ssnprintf.show.flags = flags;
         ssnprintf.show.showfn = btf_snprintf_show;
         ssnprintf.len_left = len;
         ssnprintf.len = 0;
 
         btf_type_show(btf, type_id, obj, (struct btf_show *)&ssnprintf);
 
         /* If we encountered an error, return it. */
         if (ssnprintf.show.state.status)
                 return ssnprintf.show.state.status;
 
         /* Otherwise return length we would have written */
         return ssnprintf.len;
 }
 
 #ifdef CONFIG_PROC_FS
 static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
 {
         const struct btf *btf = filp->private_data;
 
         seq_printf(m, "btf_id:\t%u\n", btf->id);
 }
 #endif
 
 static int btf_release(struct inode *inode, struct file *filp)
 {
         btf_put(filp->private_data);
         return 0;
 }
 
 const struct file_operations btf_fops = {
 #ifdef CONFIG_PROC_FS
         .show_fdinfo    = bpf_btf_show_fdinfo,
 #endif
         .release        = btf_release,
 };
 
 static int __btf_new_fd(struct btf *btf)
 {
         return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
 }
 
 int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
 {
         struct btf *btf;
         int ret;
 
         btf = btf_parse(attr, uattr, uattr_size);
         if (IS_ERR(btf))
                 return PTR_ERR(btf);
 
         ret = btf_alloc_id(btf);
         if (ret) {
                 btf_free(btf);
                 return ret;
         }
 
         /*
          * The BTF ID is published to the userspace.
          * All BTF free must go through call_rcu() from
          * now on (i.e. free by calling btf_put()).
          */
 
         ret = __btf_new_fd(btf);
         if (ret < 0)
                 btf_put(btf);
 
         return ret;
 }
 
 struct btf *btf_get_by_fd(int fd)
 {
         struct btf *btf;
         struct fd f;
 
         f = fdget(fd);
 
         if (!f.file)
                 return ERR_PTR(-EBADF);
 
         if (f.file->f_op != &btf_fops) {
                 fdput(f);
                 return ERR_PTR(-EINVAL);
         }
 
         btf = f.file->private_data;
         refcount_inc(&btf->refcnt);
         fdput(f);
 
         return btf;
 }
 
 int btf_get_info_by_fd(const struct btf *btf,
                        const union bpf_attr *attr,
                        union bpf_attr __user *uattr)
 {
         struct bpf_btf_info __user *uinfo;
         struct bpf_btf_info info;
         u32 info_copy, btf_copy;
         void __user *ubtf;
         char __user *uname;
         u32 uinfo_len, uname_len, name_len;
         int ret = 0;
 
         uinfo = u64_to_user_ptr(attr->info.info);
         uinfo_len = attr->info.info_len;
 
         info_copy = min_t(u32, uinfo_len, sizeof(info));
         memset(&info, 0, sizeof(info));
         if (copy_from_user(&info, uinfo, info_copy))
                 return -EFAULT;
 
         info.id = btf->id;
         ubtf = u64_to_user_ptr(info.btf);
         btf_copy = min_t(u32, btf->data_size, info.btf_size);
         if (copy_to_user(ubtf, btf->data, btf_copy))
                 return -EFAULT;
         info.btf_size = btf->data_size;
 
         info.kernel_btf = btf->kernel_btf;
 
         uname = u64_to_user_ptr(info.name);
         uname_len = info.name_len;
         if (!uname ^ !uname_len)
                 return -EINVAL;
 
         name_len = strlen(btf->name);
         info.name_len = name_len;
 
         if (uname) {
                 if (uname_len >= name_len + 1) {
                         if (copy_to_user(uname, btf->name, name_len + 1))
                                 return -EFAULT;
                 } else {
                         char zero = '\0';
 
                         if (copy_to_user(uname, btf->name, uname_len - 1))
                                 return -EFAULT;
                         if (put_user(zero, uname + uname_len - 1))
                                 return -EFAULT;
                         /* let user-space know about too short buffer */
                         ret = -ENOSPC;
                 }
         }
 
         if (copy_to_user(uinfo, &info, info_copy) ||
             put_user(info_copy, &uattr->info.info_len))
                 return -EFAULT;
 
         return ret;
 }
 
 int btf_get_fd_by_id(u32 id)
 {
         struct btf *btf;
         int fd;
 
         rcu_read_lock();
         btf = idr_find(&btf_idr, id);
         if (!btf || !refcount_inc_not_zero(&btf->refcnt))
                 btf = ERR_PTR(-ENOENT);
         rcu_read_unlock();
 
         if (IS_ERR(btf))
                 return PTR_ERR(btf);
 
         fd = __btf_new_fd(btf);
         if (fd < 0)
                 btf_put(btf);
 
         return fd;
 }
 
 u32 btf_obj_id(const struct btf *btf)
 {
         return btf->id;
 }
 
 bool btf_is_kernel(const struct btf *btf)
 {
         return btf->kernel_btf;
 }
 
 bool btf_is_module(const struct btf *btf)
 {
         return btf->kernel_btf && strcmp(btf->name, "vmlinux") != 0;
 }
 
 enum {
         BTF_MODULE_F_LIVE = (1 << 0),
 };
 
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 struct btf_module {
         struct list_head list;
         struct module *module;
         struct btf *btf;
         struct bin_attribute *sysfs_attr;
         int flags;
 };
 
 static LIST_HEAD(btf_modules);
 static DEFINE_MUTEX(btf_module_mutex);
 
 static ssize_t
 btf_module_read(struct file *file, struct kobject *kobj,
                 struct bin_attribute *bin_attr,
                 char *buf, loff_t off, size_t len)
 {
         const struct btf *btf = bin_attr->private;
 
         memcpy(buf, btf->data + off, len);
         return len;
 }
 
 static void purge_cand_cache(struct btf *btf);
 
 static int btf_module_notify(struct notifier_block *nb, unsigned long op,
                              void *module)
 {
         struct btf_module *btf_mod, *tmp;
         struct module *mod = module;
         struct btf *btf;
         int err = 0;
 
         if (mod->btf_data_size == 0 ||
             (op != MODULE_STATE_COMING && op != MODULE_STATE_LIVE &&
              op != MODULE_STATE_GOING))
                 goto out;
 
         switch (op) {
         case MODULE_STATE_COMING:
                 btf_mod = kzalloc(sizeof(*btf_mod), GFP_KERNEL);
                 if (!btf_mod) {
                         err = -ENOMEM;
                         goto out;
                 }
                 btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size,
                                        mod->btf_base_data, mod->btf_base_data_size);
                 if (IS_ERR(btf)) {
                         kfree(btf_mod);
                         if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
                                 pr_warn("failed to validate module [%s] BTF: %ld\n",
                                         mod->name, PTR_ERR(btf));
                                 err = PTR_ERR(btf);
                         } else {
                                 pr_warn_once("Kernel module BTF mismatch detected, BTF debug info may be unavailable for some modules\n");
                         }
                         goto out;
                 }
                 err = btf_alloc_id(btf);
                 if (err) {
                         btf_free(btf);
                         kfree(btf_mod);
                         goto out;
                 }
 
                 purge_cand_cache(NULL);
                 mutex_lock(&btf_module_mutex);
                 btf_mod->module = module;
                 btf_mod->btf = btf;
                 list_add(&btf_mod->list, &btf_modules);
                 mutex_unlock(&btf_module_mutex);
 
                 if (IS_ENABLED(CONFIG_SYSFS)) {
                         struct bin_attribute *attr;
 
                         attr = kzalloc(sizeof(*attr), GFP_KERNEL);
                         if (!attr)
                                 goto out;
 
                         sysfs_bin_attr_init(attr);
                         attr->attr.name = btf->name;
                         attr->attr.mode = 0444;
                         attr->size = btf->data_size;
                         attr->private = btf;
                         attr->read = btf_module_read;
 
                         err = sysfs_create_bin_file(btf_kobj, attr);
                         if (err) {
                                 pr_warn("failed to register module [%s] BTF in sysfs: %d\n",
                                         mod->name, err);
                                 kfree(attr);
                                 err = 0;
                                 goto out;
                         }
 
                         btf_mod->sysfs_attr = attr;
                 }
 
                 break;
         case MODULE_STATE_LIVE:
                 mutex_lock(&btf_module_mutex);
                 list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
                         if (btf_mod->module != module)
                                 continue;
 
                         btf_mod->flags |= BTF_MODULE_F_LIVE;
                         break;
                 }
                 mutex_unlock(&btf_module_mutex);
                 break;
         case MODULE_STATE_GOING:
                 mutex_lock(&btf_module_mutex);
                 list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
                         if (btf_mod->module != module)
                                 continue;
 
                         list_del(&btf_mod->list);
                         if (btf_mod->sysfs_attr)
                                 sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr);
                         purge_cand_cache(btf_mod->btf);
                         btf_put(btf_mod->btf);
                         kfree(btf_mod->sysfs_attr);
                         kfree(btf_mod);
                         break;
                 }
                 mutex_unlock(&btf_module_mutex);
                 break;
         }
 out:
         return notifier_from_errno(err);
 }
 
 static struct notifier_block btf_module_nb = {
         .notifier_call = btf_module_notify,
 };
 
 static int __init btf_module_init(void)
 {
         register_module_notifier(&btf_module_nb);
         return 0;
 }
 
 fs_initcall(btf_module_init);
 #endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
 
 struct module *btf_try_get_module(const struct btf *btf)
 {
         struct module *res = NULL;
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
         struct btf_module *btf_mod, *tmp;
 
         mutex_lock(&btf_module_mutex);
         list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
                 if (btf_mod->btf != btf)
                         continue;
 
                 /* We must only consider module whose __init routine has
                  * finished, hence we must check for BTF_MODULE_F_LIVE flag,
                  * which is set from the notifier callback for
                  * MODULE_STATE_LIVE.
                  */
                 if ((btf_mod->flags & BTF_MODULE_F_LIVE) && try_module_get(btf_mod->module))
                         res = btf_mod->module;
 
                 break;
         }
         mutex_unlock(&btf_module_mutex);
 #endif
 
         return res;
 }
 
 /* Returns struct btf corresponding to the struct module.
  * This function can return NULL or ERR_PTR.
  */
 static struct btf *btf_get_module_btf(const struct module *module)
 {
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
         struct btf_module *btf_mod, *tmp;
 #endif
         struct btf *btf = NULL;
 
         if (!module) {
                 btf = bpf_get_btf_vmlinux();
                 if (!IS_ERR_OR_NULL(btf))
                         btf_get(btf);
                 return btf;
         }
 
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
         mutex_lock(&btf_module_mutex);
         list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
                 if (btf_mod->module != module)
                         continue;
 
                 btf_get(btf_mod->btf);
                 btf = btf_mod->btf;
                 break;
         }
         mutex_unlock(&btf_module_mutex);
 #endif
 
         return btf;
 }
 
 static int check_btf_kconfigs(const struct module *module, const char *feature)
 {
         if (!module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
                 pr_err("missing vmlinux BTF, cannot register %s\n", feature);
                 return -ENOENT;
         }
         if (module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
                 pr_warn("missing module BTF, cannot register %s\n", feature);
         return 0;
 }
 
 BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
 {
         struct btf *btf = NULL;
         int btf_obj_fd = 0;
         long ret;
 
         if (flags)
                 return -EINVAL;
 
         if (name_sz <= 1 || name[name_sz - 1])
                 return -EINVAL;
 
         ret = bpf_find_btf_id(name, kind, &btf);
         if (ret > 0 && btf_is_module(btf)) {
                 btf_obj_fd = __btf_new_fd(btf);
                 if (btf_obj_fd < 0) {
                         btf_put(btf);
                         return btf_obj_fd;
                 }
                 return ret | (((u64)btf_obj_fd) << 32);
         }
         if (ret > 0)
                 btf_put(btf);
         return ret;
 }
 
 const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
         .func           = bpf_btf_find_by_name_kind,
         .gpl_only       = false,
         .ret_type       = RET_INTEGER,
         .arg1_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
         .arg2_type      = ARG_CONST_SIZE,
         .arg3_type      = ARG_ANYTHING,
         .arg4_type      = ARG_ANYTHING,
 };
 
 BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE)
 #define BTF_TRACING_TYPE(name, type) BTF_ID(struct, type)
 BTF_TRACING_TYPE_xxx
 #undef BTF_TRACING_TYPE
 
 static int btf_check_iter_kfuncs(struct btf *btf, const char *func_name,
                                  const struct btf_type *func, u32 func_flags)
 {
         u32 flags = func_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY);
         const char *name, *sfx, *iter_name;
         const struct btf_param *arg;
         const struct btf_type *t;
         char exp_name[128];
         u32 nr_args;
 
         /* exactly one of KF_ITER_{NEW,NEXT,DESTROY} can be set */
         if (!flags || (flags & (flags - 1)))
                 return -EINVAL;
 
         /* any BPF iter kfunc should have `struct bpf_iter_<type> *` first arg */
         nr_args = btf_type_vlen(func);
         if (nr_args < 1)
                 return -EINVAL;
 
         arg = &btf_params(func)[0];
         t = btf_type_skip_modifiers(btf, arg->type, NULL);
         if (!t || !btf_type_is_ptr(t))
                 return -EINVAL;
         t = btf_type_skip_modifiers(btf, t->type, NULL);
         if (!t || !__btf_type_is_struct(t))
                 return -EINVAL;
 
         name = btf_name_by_offset(btf, t->name_off);
         if (!name || strncmp(name, ITER_PREFIX, sizeof(ITER_PREFIX) - 1))
                 return -EINVAL;
 
         /* sizeof(struct bpf_iter_<type>) should be a multiple of 8 to
          * fit nicely in stack slots
          */
         if (t->size == 0 || (t->size % 8))
                 return -EINVAL;
 
         /* validate bpf_iter_<type>_{new,next,destroy}(struct bpf_iter_<type> *)
          * naming pattern
          */
         iter_name = name + sizeof(ITER_PREFIX) - 1;
         if (flags & KF_ITER_NEW)
                 sfx = "new";
         else if (flags & KF_ITER_NEXT)
                 sfx = "next";
         else /* (flags & KF_ITER_DESTROY) */
                 sfx = "destroy";
 
         snprintf(exp_name, sizeof(exp_name), "bpf_iter_%s_%s", iter_name, sfx);
         if (strcmp(func_name, exp_name))
                 return -EINVAL;
 
         /* only iter constructor should have extra arguments */
         if (!(flags & KF_ITER_NEW) && nr_args != 1)
                 return -EINVAL;
 
         if (flags & KF_ITER_NEXT) {
                 /* bpf_iter_<type>_next() should return pointer */
                 t = btf_type_skip_modifiers(btf, func->type, NULL);
                 if (!t || !btf_type_is_ptr(t))
                         return -EINVAL;
         }
 
         if (flags & KF_ITER_DESTROY) {
                 /* bpf_iter_<type>_destroy() should return void */
                 t = btf_type_by_id(btf, func->type);
                 if (!t || !btf_type_is_void(t))
                         return -EINVAL;
         }
 
         return 0;
 }
 
 static int btf_check_kfunc_protos(struct btf *btf, u32 func_id, u32 func_flags)
 {
         const struct btf_type *func;
         const char *func_name;
         int err;
 
         /* any kfunc should be FUNC -> FUNC_PROTO */
         func = btf_type_by_id(btf, func_id);
         if (!func || !btf_type_is_func(func))
                 return -EINVAL;
 
         /* sanity check kfunc name */
         func_name = btf_name_by_offset(btf, func->name_off);
         if (!func_name || !func_name[0])
                 return -EINVAL;
 
         func = btf_type_by_id(btf, func->type);
         if (!func || !btf_type_is_func_proto(func))
                 return -EINVAL;
 
         if (func_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY)) {
                 err = btf_check_iter_kfuncs(btf, func_name, func, func_flags);
                 if (err)
                         return err;
         }
 
         return 0;
 }
 
 /* Kernel Function (kfunc) BTF ID set registration API */
 
 static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
                                   const struct btf_kfunc_id_set *kset)
 {
         struct btf_kfunc_hook_filter *hook_filter;
         struct btf_id_set8 *add_set = kset->set;
         bool vmlinux_set = !btf_is_module(btf);
         bool add_filter = !!kset->filter;
         struct btf_kfunc_set_tab *tab;
         struct btf_id_set8 *set;
         u32 set_cnt, i;
         int ret;
 
         if (hook >= BTF_KFUNC_HOOK_MAX) {
                 ret = -EINVAL;
                 goto end;
         }
 
         if (!add_set->cnt)
                 return 0;
 
         tab = btf->kfunc_set_tab;
 
         if (tab && add_filter) {
                 u32 i;
 
                 hook_filter = &tab->hook_filters[hook];
                 for (i = 0; i < hook_filter->nr_filters; i++) {
                         if (hook_filter->filters[i] == kset->filter) {
                                 add_filter = false;
                                 break;
                         }
                 }
 
                 if (add_filter && hook_filter->nr_filters == BTF_KFUNC_FILTER_MAX_CNT) {
                         ret = -E2BIG;
                         goto end;
                 }
         }
 
         if (!tab) {
                 tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN);
                 if (!tab)
                         return -ENOMEM;
                 btf->kfunc_set_tab = tab;
         }
 
         set = tab->sets[hook];
         /* Warn when register_btf_kfunc_id_set is called twice for the same hook
          * for module sets.
          */
         if (WARN_ON_ONCE(set && !vmlinux_set)) {
                 ret = -EINVAL;
                 goto end;
         }
 
         /* In case of vmlinux sets, there may be more than one set being
          * registered per hook. To create a unified set, we allocate a new set
          * and concatenate all individual sets being registered. While each set
          * is individually sorted, they may become unsorted when concatenated,
          * hence re-sorting the final set again is required to make binary
          * searching the set using btf_id_set8_contains function work.
          *
          * For module sets, we need to allocate as we may need to relocate
          * BTF ids.
          */
         set_cnt = set ? set->cnt : 0;
 
         if (set_cnt > U32_MAX - add_set->cnt) {
                 ret = -EOVERFLOW;
                 goto end;
         }
 
         if (set_cnt + add_set->cnt > BTF_KFUNC_SET_MAX_CNT) {
                 ret = -E2BIG;
                 goto end;
         }
 
         /* Grow set */
         set = krealloc(tab->sets[hook],
                        offsetof(struct btf_id_set8, pairs[set_cnt + add_set->cnt]),
                        GFP_KERNEL | __GFP_NOWARN);
         if (!set) {
                 ret = -ENOMEM;
                 goto end;
         }
 
         /* For newly allocated set, initialize set->cnt to 0 */
         if (!tab->sets[hook])
                 set->cnt = 0;
         tab->sets[hook] = set;
 
         /* Concatenate the two sets */
         memcpy(set->pairs + set->cnt, add_set->pairs, add_set->cnt * sizeof(set->pairs[0]));
         /* Now that the set is copied, update with relocated BTF ids */
         for (i = set->cnt; i < set->cnt + add_set->cnt; i++)
                 set->pairs[i].id = btf_relocate_id(btf, set->pairs[i].id);
 
         set->cnt += add_set->cnt;
 
         sort(set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func, NULL);
 
         if (add_filter) {
                 hook_filter = &tab->hook_filters[hook];
                 hook_filter->filters[hook_filter->nr_filters++] = kset->filter;
         }
         return 0;
 end:
         btf_free_kfunc_set_tab(btf);
         return ret;
 }
 
 static u32 *__btf_kfunc_id_set_contains(const struct btf *btf,
                                         enum btf_kfunc_hook hook,
                                         u32 kfunc_btf_id,
                                         const struct bpf_prog *prog)
 {
         struct btf_kfunc_hook_filter *hook_filter;
         struct btf_id_set8 *set;
         u32 *id, i;
 
         if (hook >= BTF_KFUNC_HOOK_MAX)
                 return NULL;
         if (!btf->kfunc_set_tab)
                 return NULL;
         hook_filter = &btf->kfunc_set_tab->hook_filters[hook];
         for (i = 0; i < hook_filter->nr_filters; i++) {
                 if (hook_filter->filters[i](prog, kfunc_btf_id))
                         return NULL;
         }
         set = btf->kfunc_set_tab->sets[hook];
         if (!set)
                 return NULL;
         id = btf_id_set8_contains(set, kfunc_btf_id);
         if (!id)
                 return NULL;
         /* The flags for BTF ID are located next to it */
         return id + 1;
 }
 
 static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
 {
         switch (prog_type) {
         case BPF_PROG_TYPE_UNSPEC:
                 return BTF_KFUNC_HOOK_COMMON;
         case BPF_PROG_TYPE_XDP:
                 return BTF_KFUNC_HOOK_XDP;
         case BPF_PROG_TYPE_SCHED_CLS:
                 return BTF_KFUNC_HOOK_TC;
         case BPF_PROG_TYPE_STRUCT_OPS:
                 return BTF_KFUNC_HOOK_STRUCT_OPS;
         case BPF_PROG_TYPE_TRACING:
         case BPF_PROG_TYPE_LSM:
                 return BTF_KFUNC_HOOK_TRACING;
         case BPF_PROG_TYPE_SYSCALL:
                 return BTF_KFUNC_HOOK_SYSCALL;
         case BPF_PROG_TYPE_CGROUP_SKB:
         case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
                 return BTF_KFUNC_HOOK_CGROUP_SKB;
         case BPF_PROG_TYPE_SCHED_ACT:
                 return BTF_KFUNC_HOOK_SCHED_ACT;
         case BPF_PROG_TYPE_SK_SKB:
                 return BTF_KFUNC_HOOK_SK_SKB;
         case BPF_PROG_TYPE_SOCKET_FILTER:
                 return BTF_KFUNC_HOOK_SOCKET_FILTER;
         case BPF_PROG_TYPE_LWT_OUT:
         case BPF_PROG_TYPE_LWT_IN:
         case BPF_PROG_TYPE_LWT_XMIT:
         case BPF_PROG_TYPE_LWT_SEG6LOCAL:
                 return BTF_KFUNC_HOOK_LWT;
         case BPF_PROG_TYPE_NETFILTER:
                 return BTF_KFUNC_HOOK_NETFILTER;
         case BPF_PROG_TYPE_KPROBE:
                 return BTF_KFUNC_HOOK_KPROBE;
         default:
                 return BTF_KFUNC_HOOK_MAX;
         }
 }
 
 /* Caution:
  * Reference to the module (obtained using btf_try_get_module) corresponding to
  * the struct btf *MUST* be held when calling this function from verifier
  * context. This is usually true as we stash references in prog's kfunc_btf_tab;
  * keeping the reference for the duration of the call provides the necessary
  * protection for looking up a well-formed btf->kfunc_set_tab.
  */
 u32 *btf_kfunc_id_set_contains(const struct btf *btf,
                                u32 kfunc_btf_id,
                                const struct bpf_prog *prog)
 {
         enum bpf_prog_type prog_type = resolve_prog_type(prog);
         enum btf_kfunc_hook hook;
         u32 *kfunc_flags;
 
         kfunc_flags = __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_COMMON, kfunc_btf_id, prog);
         if (kfunc_flags)
                 return kfunc_flags;
 
         hook = bpf_prog_type_to_kfunc_hook(prog_type);
         return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id, prog);
 }
 
 u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
                                 const struct bpf_prog *prog)
 {
         return __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_FMODRET, kfunc_btf_id, prog);
 }
 
 static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
                                        const struct btf_kfunc_id_set *kset)
 {
         struct btf *btf;
         int ret, i;
 
         btf = btf_get_module_btf(kset->owner);
         if (!btf)
                 return check_btf_kconfigs(kset->owner, "kfunc");
         if (IS_ERR(btf))
                 return PTR_ERR(btf);
 
         for (i = 0; i < kset->set->cnt; i++) {
                 ret = btf_check_kfunc_protos(btf, btf_relocate_id(btf, kset->set->pairs[i].id),
                                              kset->set->pairs[i].flags);
                 if (ret)
                         goto err_out;
         }
 
         ret = btf_populate_kfunc_set(btf, hook, kset);
 
 err_out:
         btf_put(btf);
         return ret;
 }
 
 /* This function must be invoked only from initcalls/module init functions */
 int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
                               const struct btf_kfunc_id_set *kset)
 {
         enum btf_kfunc_hook hook;
 
         /* All kfuncs need to be tagged as such in BTF.
          * WARN() for initcall registrations that do not check errors.
          */
         if (!(kset->set->flags & BTF_SET8_KFUNCS)) {
                 WARN_ON(!kset->owner);
                 return -EINVAL;
         }
 
         hook = bpf_prog_type_to_kfunc_hook(prog_type);
         return __register_btf_kfunc_id_set(hook, kset);
 }
 EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);
 
 /* This function must be invoked only from initcalls/module init functions */
 int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset)
 {
         return __register_btf_kfunc_id_set(BTF_KFUNC_HOOK_FMODRET, kset);
 }
 EXPORT_SYMBOL_GPL(register_btf_fmodret_id_set);
 
 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
 {
         struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
         struct btf_id_dtor_kfunc *dtor;
 
         if (!tab)
                 return -ENOENT;
         /* Even though the size of tab->dtors[0] is > sizeof(u32), we only need
          * to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func.
          */
         BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0);
         dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func);
         if (!dtor)
                 return -ENOENT;
         return dtor->kfunc_btf_id;
 }
 
 static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc *dtors, u32 cnt)
 {
         const struct btf_type *dtor_func, *dtor_func_proto, *t;
         const struct btf_param *args;
         s32 dtor_btf_id;
         u32 nr_args, i;
 
         for (i = 0; i < cnt; i++) {
                 dtor_btf_id = btf_relocate_id(btf, dtors[i].kfunc_btf_id);
 
                 dtor_func = btf_type_by_id(btf, dtor_btf_id);
                 if (!dtor_func || !btf_type_is_func(dtor_func))
                         return -EINVAL;
 
                 dtor_func_proto = btf_type_by_id(btf, dtor_func->type);
                 if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto))
                         return -EINVAL;
 
                 /* Make sure the prototype of the destructor kfunc is 'void func(type *)' */
                 t = btf_type_by_id(btf, dtor_func_proto->type);
                 if (!t || !btf_type_is_void(t))
                         return -EINVAL;
 
                 nr_args = btf_type_vlen(dtor_func_proto);
                 if (nr_args != 1)
                         return -EINVAL;
                 args = btf_params(dtor_func_proto);
                 t = btf_type_by_id(btf, args[0].type);
                 /* Allow any pointer type, as width on targets Linux supports
                  * will be same for all pointer types (i.e. sizeof(void *))
                  */
                 if (!t || !btf_type_is_ptr(t))
                         return -EINVAL;
         }
         return 0;
 }
 
 /* This function must be invoked only from initcalls/module init functions */
 int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
                                 struct module *owner)
 {
         struct btf_id_dtor_kfunc_tab *tab;
         struct btf *btf;
         u32 tab_cnt, i;
         int ret;
 
         btf = btf_get_module_btf(owner);
         if (!btf)
                 return check_btf_kconfigs(owner, "dtor kfuncs");
         if (IS_ERR(btf))
                 return PTR_ERR(btf);
 
         if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
                 pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
                 ret = -E2BIG;
                 goto end;
         }
 
         /* Ensure that the prototype of dtor kfuncs being registered is sane */
         ret = btf_check_dtor_kfuncs(btf, dtors, add_cnt);
         if (ret < 0)
                 goto end;
 
         tab = btf->dtor_kfunc_tab;
         /* Only one call allowed for modules */
         if (WARN_ON_ONCE(tab && btf_is_module(btf))) {
                 ret = -EINVAL;
                 goto end;
         }
 
         tab_cnt = tab ? tab->cnt : 0;
         if (tab_cnt > U32_MAX - add_cnt) {
                 ret = -EOVERFLOW;
                 goto end;
         }
         if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
                 pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
                 ret = -E2BIG;
                 goto end;
         }
 
         tab = krealloc(btf->dtor_kfunc_tab,
                        offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]),
                        GFP_KERNEL | __GFP_NOWARN);
         if (!tab) {
                 ret = -ENOMEM;
                 goto end;
         }
 
         if (!btf->dtor_kfunc_tab)
                 tab->cnt = 0;
         btf->dtor_kfunc_tab = tab;
 
         memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0]));
 
         /* remap BTF ids based on BTF relocation (if any) */
         for (i = tab_cnt; i < tab_cnt + add_cnt; i++) {
                 tab->dtors[i].btf_id = btf_relocate_id(btf, tab->dtors[i].btf_id);
                 tab->dtors[i].kfunc_btf_id = btf_relocate_id(btf, tab->dtors[i].kfunc_btf_id);
         }
 
         tab->cnt += add_cnt;
 
         sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL);
 
 end:
         if (ret)
                 btf_free_dtor_kfunc_tab(btf);
         btf_put(btf);
         return ret;
 }
 EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs);
 
 #define MAX_TYPES_ARE_COMPAT_DEPTH 2
 
 /* Check local and target types for compatibility. This check is used for
  * type-based CO-RE relocations and follow slightly different rules than
  * field-based relocations. This function assumes that root types were already
  * checked for name match. Beyond that initial root-level name check, names
  * are completely ignored. Compatibility rules are as follows:
  *   - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs/ENUM64s are considered compatible, but
  *     kind should match for local and target types (i.e., STRUCT is not
  *     compatible with UNION);
  *   - for ENUMs/ENUM64s, the size is ignored;
  *   - for INT, size and signedness are ignored;
  *   - for ARRAY, dimensionality is ignored, element types are checked for
  *     compatibility recursively;
  *   - CONST/VOLATILE/RESTRICT modifiers are ignored;
  *   - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
  *   - FUNC_PROTOs are compatible if they have compatible signature: same
  *     number of input args and compatible return and argument types.
  * These rules are not set in stone and probably will be adjusted as we get
  * more experience with using BPF CO-RE relocations.
  */
 int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
                               const struct btf *targ_btf, __u32 targ_id)
 {
         return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id,
                                            MAX_TYPES_ARE_COMPAT_DEPTH);
 }
 
 #define MAX_TYPES_MATCH_DEPTH 2
 
 int bpf_core_types_match(const struct btf *local_btf, u32 local_id,
                          const struct btf *targ_btf, u32 targ_id)
 {
         return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false,
                                       MAX_TYPES_MATCH_DEPTH);
 }
 
 static bool bpf_core_is_flavor_sep(const char *s)
 {
         /* check X___Y name pattern, where X and Y are not underscores */
         return s[0] != '_' &&                                 /* X */
                s[1] == '_' && s[2] == '_' && s[3] == '_' &&   /* ___ */
                s[4] != '_';                                   /* Y */
 }
 
 size_t bpf_core_essential_name_len(const char *name)
 {
         size_t n = strlen(name);
         int i;
 
         for (i = n - 5; i >= 0; i--) {
                 if (bpf_core_is_flavor_sep(name + i))
                         return i + 1;
         }
         return n;
 }
 
 static void bpf_free_cands(struct bpf_cand_cache *cands)
 {
         if (!cands->cnt)
                 /* empty candidate array was allocated on stack */
                 return;
         kfree(cands);
 }
 
 static void bpf_free_cands_from_cache(struct bpf_cand_cache *cands)
 {
         kfree(cands->name);
         kfree(cands);
 }
 
 #define VMLINUX_CAND_CACHE_SIZE 31
 static struct bpf_cand_cache *vmlinux_cand_cache[VMLINUX_CAND_CACHE_SIZE];
 
 #define MODULE_CAND_CACHE_SIZE 31
 static struct bpf_cand_cache *module_cand_cache[MODULE_CAND_CACHE_SIZE];
 
 static void __print_cand_cache(struct bpf_verifier_log *log,
                                struct bpf_cand_cache **cache,
                                int cache_size)
 {
         struct bpf_cand_cache *cc;
         int i, j;
 
         for (i = 0; i < cache_size; i++) {
                 cc = cache[i];
                 if (!cc)
                         continue;
                 bpf_log(log, "[%d]%s(", i, cc->name);
                 for (j = 0; j < cc->cnt; j++) {
                         bpf_log(log, "%d", cc->cands[j].id);
                         if (j < cc->cnt - 1)
                                 bpf_log(log, " ");
                 }
                 bpf_log(log, "), ");
         }
 }
 
 static void print_cand_cache(struct bpf_verifier_log *log)
 {
         mutex_lock(&cand_cache_mutex);
         bpf_log(log, "vmlinux_cand_cache:");
         __print_cand_cache(log, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
         bpf_log(log, "\nmodule_cand_cache:");
         __print_cand_cache(log, module_cand_cache, MODULE_CAND_CACHE_SIZE);
         bpf_log(log, "\n");
         mutex_unlock(&cand_cache_mutex);
 }
 
 static u32 hash_cands(struct bpf_cand_cache *cands)
 {
         return jhash(cands->name, cands->name_len, 0);
 }
 
 static struct bpf_cand_cache *check_cand_cache(struct bpf_cand_cache *cands,
                                                struct bpf_cand_cache **cache,
                                                int cache_size)
 {
         struct bpf_cand_cache *cc = cache[hash_cands(cands) % cache_size];
 
         if (cc && cc->name_len == cands->name_len &&
             !strncmp(cc->name, cands->name, cands->name_len))
                 return cc;
         return NULL;
 }
 
 static size_t sizeof_cands(int cnt)
 {
         return offsetof(struct bpf_cand_cache, cands[cnt]);
 }
 
 static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands,
                                                   struct bpf_cand_cache **cache,
                                                   int cache_size)
 {
         struct bpf_cand_cache **cc = &cache[hash_cands(cands) % cache_size], *new_cands;
 
         if (*cc) {
                 bpf_free_cands_from_cache(*cc);
                 *cc = NULL;
         }
         new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL);
         if (!new_cands) {
                 bpf_free_cands(cands);
                 return ERR_PTR(-ENOMEM);
         }
         /* strdup the name, since it will stay in cache.
          * the cands->name points to strings in prog's BTF and the prog can be unloaded.
          */
         new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL);
         bpf_free_cands(cands);
         if (!new_cands->name) {
                 kfree(new_cands);
                 return ERR_PTR(-ENOMEM);
         }
         *cc = new_cands;
         return new_cands;
 }
 
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 static void __purge_cand_cache(struct btf *btf, struct bpf_cand_cache **cache,
                                int cache_size)
 {
         struct bpf_cand_cache *cc;
         int i, j;
 
         for (i = 0; i < cache_size; i++) {
                 cc = cache[i];
                 if (!cc)
                         continue;
                 if (!btf) {
                         /* when new module is loaded purge all of module_cand_cache,
                          * since new module might have candidates with the name
                          * that matches cached cands.
                          */
                         bpf_free_cands_from_cache(cc);
                         cache[i] = NULL;
                         continue;
                 }
                 /* when module is unloaded purge cache entries
                  * that match module's btf
                  */
                 for (j = 0; j < cc->cnt; j++)
                         if (cc->cands[j].btf == btf) {
                                 bpf_free_cands_from_cache(cc);
                                 cache[i] = NULL;
                                 break;
                         }
         }
 
 }
 
 static void purge_cand_cache(struct btf *btf)
 {
         mutex_lock(&cand_cache_mutex);
         __purge_cand_cache(btf, module_cand_cache, MODULE_CAND_CACHE_SIZE);
         mutex_unlock(&cand_cache_mutex);
 }
 #endif
 
 static struct bpf_cand_cache *
 bpf_core_add_cands(struct bpf_cand_cache *cands, const struct btf *targ_btf,
                    int targ_start_id)
 {
         struct bpf_cand_cache *new_cands;
         const struct btf_type *t;
         const char *targ_name;
         size_t targ_essent_len;
         int n, i;
 
         n = btf_nr_types(targ_btf);
         for (i = targ_start_id; i < n; i++) {
                 t = btf_type_by_id(targ_btf, i);
                 if (btf_kind(t) != cands->kind)
                         continue;
 
                 targ_name = btf_name_by_offset(targ_btf, t->name_off);
                 if (!targ_name)
                         continue;
 
                 /* the resched point is before strncmp to make sure that search
                  * for non-existing name will have a chance to schedule().
                  */
                 cond_resched();
 
                 if (strncmp(cands->name, targ_name, cands->name_len) != 0)
                         continue;
 
                 targ_essent_len = bpf_core_essential_name_len(targ_name);
                 if (targ_essent_len != cands->name_len)
                         continue;
 
                 /* most of the time there is only one candidate for a given kind+name pair */
                 new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL);
                 if (!new_cands) {
                         bpf_free_cands(cands);
                         return ERR_PTR(-ENOMEM);
                 }
 
                 memcpy(new_cands, cands, sizeof_cands(cands->cnt));
                 bpf_free_cands(cands);
                 cands = new_cands;
                 cands->cands[cands->cnt].btf = targ_btf;
                 cands->cands[cands->cnt].id = i;
                 cands->cnt++;
         }
         return cands;
 }
 
 static struct bpf_cand_cache *
 bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id)
 {
         struct bpf_cand_cache *cands, *cc, local_cand = {};
         const struct btf *local_btf = ctx->btf;
         const struct btf_type *local_type;
         const struct btf *main_btf;
         size_t local_essent_len;
         struct btf *mod_btf;
         const char *name;
         int id;
 
         main_btf = bpf_get_btf_vmlinux();
         if (IS_ERR(main_btf))
                 return ERR_CAST(main_btf);
         if (!main_btf)
                 return ERR_PTR(-EINVAL);
 
         local_type = btf_type_by_id(local_btf, local_type_id);
         if (!local_type)
                 return ERR_PTR(-EINVAL);
 
         name = btf_name_by_offset(local_btf, local_type->name_off);
         if (str_is_empty(name))
                 return ERR_PTR(-EINVAL);
         local_essent_len = bpf_core_essential_name_len(name);
 
         cands = &local_cand;
         cands->name = name;
         cands->kind = btf_kind(local_type);
         cands->name_len = local_essent_len;
 
         cc = check_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
         /* cands is a pointer to stack here */
         if (cc) {
                 if (cc->cnt)
                         return cc;
                 goto check_modules;
         }
 
         /* Attempt to find target candidates in vmlinux BTF first */
         cands = bpf_core_add_cands(cands, main_btf, 1);
         if (IS_ERR(cands))
                 return ERR_CAST(cands);
 
         /* cands is a pointer to kmalloced memory here if cands->cnt > 0 */
 
         /* populate cache even when cands->cnt == 0 */
         cc = populate_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
         if (IS_ERR(cc))
                 return ERR_CAST(cc);
 
         /* if vmlinux BTF has any candidate, don't go for module BTFs */
         if (cc->cnt)
                 return cc;
 
 check_modules:
         /* cands is a pointer to stack here and cands->cnt == 0 */
         cc = check_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
         if (cc)
                 /* if cache has it return it even if cc->cnt == 0 */
                 return cc;
 
         /* If candidate is not found in vmlinux's BTF then search in module's BTFs */
         spin_lock_bh(&btf_idr_lock);
         idr_for_each_entry(&btf_idr, mod_btf, id) {
                 if (!btf_is_module(mod_btf))
                         continue;
                 /* linear search could be slow hence unlock/lock
                  * the IDR to avoiding holding it for too long
                  */
                 btf_get(mod_btf);
                 spin_unlock_bh(&btf_idr_lock);
                 cands = bpf_core_add_cands(cands, mod_btf, btf_nr_types(main_btf));
                 btf_put(mod_btf);
                 if (IS_ERR(cands))
                         return ERR_CAST(cands);
                 spin_lock_bh(&btf_idr_lock);
         }
         spin_unlock_bh(&btf_idr_lock);
         /* cands is a pointer to kmalloced memory here if cands->cnt > 0
          * or pointer to stack if cands->cnd == 0.
          * Copy it into the cache even when cands->cnt == 0 and
          * return the result.
          */
         return populate_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
 }
 
 int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
                    int relo_idx, void *insn)
 {
         bool need_cands = relo->kind != BPF_CORE_TYPE_ID_LOCAL;
         struct bpf_core_cand_list cands = {};
         struct bpf_core_relo_res targ_res;
         struct bpf_core_spec *specs;
         const struct btf_type *type;
         int err;
 
         /* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5"
          * into arrays of btf_ids of struct fields and array indices.
          */
         specs = kcalloc(3, sizeof(*specs), GFP_KERNEL);
         if (!specs)
                 return -ENOMEM;
 
         type = btf_type_by_id(ctx->btf, relo->type_id);
         if (!type) {
                 bpf_log(ctx->log, "relo #%u: bad type id %u\n",
                         relo_idx, relo->type_id);
                 return -EINVAL;
         }
 
         if (need_cands) {
                 struct bpf_cand_cache *cc;
                 int i;
 
                 mutex_lock(&cand_cache_mutex);
                 cc = bpf_core_find_cands(ctx, relo->type_id);
                 if (IS_ERR(cc)) {
                         bpf_log(ctx->log, "target candidate search failed for %d\n",
                                 relo->type_id);
                         err = PTR_ERR(cc);
                         goto out;
                 }
                 if (cc->cnt) {
                         cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL);
                         if (!cands.cands) {
                                 err = -ENOMEM;
                                 goto out;
                         }
                 }
                 for (i = 0; i < cc->cnt; i++) {
                         bpf_log(ctx->log,
                                 "CO-RE relocating %s %s: found target candidate [%d]\n",
                                 btf_kind_str[cc->kind], cc->name, cc->cands[i].id);
                         cands.cands[i].btf = cc->cands[i].btf;
                         cands.cands[i].id = cc->cands[i].id;
                 }
                 cands.len = cc->cnt;
                 /* cand_cache_mutex needs to span the cache lookup and
                  * copy of btf pointer into bpf_core_cand_list,
                  * since module can be unloaded while bpf_core_calc_relo_insn
                  * is working with module's btf.
                  */
         }
 
         err = bpf_core_calc_relo_insn((void *)ctx->log, relo, relo_idx, ctx->btf, &cands, specs,
                                       &targ_res);
         if (err)
                 goto out;
 
         err = bpf_core_patch_insn((void *)ctx->log, insn, relo->insn_off / 8, relo, relo_idx,
                                   &targ_res);
 
 out:
         kfree(specs);
         if (need_cands) {
                 kfree(cands.cands);
                 mutex_unlock(&cand_cache_mutex);
                 if (ctx->log->level & BPF_LOG_LEVEL2)
                         print_cand_cache(ctx->log);
         }
         return err;
 }
 
 bool btf_nested_type_is_trusted(struct bpf_verifier_log *log,
                                 const struct bpf_reg_state *reg,
                                 const char *field_name, u32 btf_id, const char *suffix)
 {
         struct btf *btf = reg->btf;
         const struct btf_type *walk_type, *safe_type;
         const char *tname;
         char safe_tname[64];
         long ret, safe_id;
         const struct btf_member *member;
         u32 i;
 
         walk_type = btf_type_by_id(btf, reg->btf_id);
         if (!walk_type)
                 return false;
 
         tname = btf_name_by_offset(btf, walk_type->name_off);
 
         ret = snprintf(safe_tname, sizeof(safe_tname), "%s%s", tname, suffix);
         if (ret >= sizeof(safe_tname))
                 return false;
 
         safe_id = btf_find_by_name_kind(btf, safe_tname, BTF_INFO_KIND(walk_type->info));
         if (safe_id < 0)
                 return false;
 
         safe_type = btf_type_by_id(btf, safe_id);
         if (!safe_type)
                 return false;
 
         for_each_member(i, safe_type, member) {
                 const char *m_name = __btf_name_by_offset(btf, member->name_off);
                 const struct btf_type *mtype = btf_type_by_id(btf, member->type);
                 u32 id;
 
                 if (!btf_type_is_ptr(mtype))
                         continue;
 
                 btf_type_skip_modifiers(btf, mtype->type, &id);
                 /* If we match on both type and name, the field is considered trusted. */
                 if (btf_id == id && !strcmp(field_name, m_name))
                         return true;
         }
 
         return false;
 }
 
 bool btf_type_ids_nocast_alias(struct bpf_verifier_log *log,
                                const struct btf *reg_btf, u32 reg_id,
                                const struct btf *arg_btf, u32 arg_id)
 {
         const char *reg_name, *arg_name, *search_needle;
         const struct btf_type *reg_type, *arg_type;
         int reg_len, arg_len, cmp_len;
         size_t pattern_len = sizeof(NOCAST_ALIAS_SUFFIX) - sizeof(char);
 
         reg_type = btf_type_by_id(reg_btf, reg_id);
         if (!reg_type)
                 return false;
 
         arg_type = btf_type_by_id(arg_btf, arg_id);
         if (!arg_type)
                 return false;
 
         reg_name = btf_name_by_offset(reg_btf, reg_type->name_off);
         arg_name = btf_name_by_offset(arg_btf, arg_type->name_off);
 
         reg_len = strlen(reg_name);
         arg_len = strlen(arg_name);
 
         /* Exactly one of the two type names may be suffixed with ___init, so
          * if the strings are the same size, they can't possibly be no-cast
          * aliases of one another. If you have two of the same type names, e.g.
          * they're both nf_conn___init, it would be improper to return true
          * because they are _not_ no-cast aliases, they are the same type.
          */
         if (reg_len == arg_len)
                 return false;
 
         /* Either of the two names must be the other name, suffixed with ___init. */
         if ((reg_len != arg_len + pattern_len) &&
             (arg_len != reg_len + pattern_len))
                 return false;
 
         if (reg_len < arg_len) {
                 search_needle = strstr(arg_name, NOCAST_ALIAS_SUFFIX);
                 cmp_len = reg_len;
         } else {
                 search_needle = strstr(reg_name, NOCAST_ALIAS_SUFFIX);
                 cmp_len = arg_len;
         }
 
         if (!search_needle)
                 return false;
 
         /* ___init suffix must come at the end of the name */
         if (*(search_needle + pattern_len) != '\0')
                 return false;
 
         return !strncmp(reg_name, arg_name, cmp_len);
 }
 
 #ifdef CONFIG_BPF_JIT
 static int
 btf_add_struct_ops(struct btf *btf, struct bpf_struct_ops *st_ops,
                    struct bpf_verifier_log *log)
 {
         struct btf_struct_ops_tab *tab, *new_tab;
         int i, err;
 
         tab = btf->struct_ops_tab;
         if (!tab) {
                 tab = kzalloc(offsetof(struct btf_struct_ops_tab, ops[4]),
                               GFP_KERNEL);
                 if (!tab)
                         return -ENOMEM;
                 tab->capacity = 4;
                 btf->struct_ops_tab = tab;
         }
 
         for (i = 0; i < tab->cnt; i++)
                 if (tab->ops[i].st_ops == st_ops)
                         return -EEXIST;
 
         if (tab->cnt == tab->capacity) {
                 new_tab = krealloc(tab,
                                    offsetof(struct btf_struct_ops_tab,
                                             ops[tab->capacity * 2]),
                                    GFP_KERNEL);
                 if (!new_tab)
                         return -ENOMEM;
                 tab = new_tab;
                 tab->capacity *= 2;
                 btf->struct_ops_tab = tab;
         }
 
         tab->ops[btf->struct_ops_tab->cnt].st_ops = st_ops;
 
         err = bpf_struct_ops_desc_init(&tab->ops[btf->struct_ops_tab->cnt], btf, log);
         if (err)
                 return err;
 
         btf->struct_ops_tab->cnt++;
 
         return 0;
 }
 
 const struct bpf_struct_ops_desc *
 bpf_struct_ops_find_value(struct btf *btf, u32 value_id)
 {
         const struct bpf_struct_ops_desc *st_ops_list;
         unsigned int i;
         u32 cnt;
 
         if (!value_id)
                 return NULL;
         if (!btf->struct_ops_tab)
                 return NULL;
 
         cnt = btf->struct_ops_tab->cnt;
         st_ops_list = btf->struct_ops_tab->ops;
         for (i = 0; i < cnt; i++) {
                 if (st_ops_list[i].value_id == value_id)
                         return &st_ops_list[i];
         }
 
         return NULL;
 }
 
 const struct bpf_struct_ops_desc *
 bpf_struct_ops_find(struct btf *btf, u32 type_id)
 {
         const struct bpf_struct_ops_desc *st_ops_list;
         unsigned int i;
         u32 cnt;
 
         if (!type_id)
                 return NULL;
         if (!btf->struct_ops_tab)
                 return NULL;
 
         cnt = btf->struct_ops_tab->cnt;
         st_ops_list = btf->struct_ops_tab->ops;
         for (i = 0; i < cnt; i++) {
                 if (st_ops_list[i].type_id == type_id)
                         return &st_ops_list[i];
         }
 
         return NULL;
 }
 
 int __register_bpf_struct_ops(struct bpf_struct_ops *st_ops)
 {
         struct bpf_verifier_log *log;
         struct btf *btf;
         int err = 0;
 
         btf = btf_get_module_btf(st_ops->owner);
         if (!btf)
                 return check_btf_kconfigs(st_ops->owner, "struct_ops");
         if (IS_ERR(btf))
                 return PTR_ERR(btf);
 
         log = kzalloc(sizeof(*log), GFP_KERNEL | __GFP_NOWARN);
         if (!log) {
                 err = -ENOMEM;
                 goto errout;
         }
 
         log->level = BPF_LOG_KERNEL;
 
         err = btf_add_struct_ops(btf, st_ops, log);
 
 errout:
         kfree(log);
         btf_put(btf);
 
         return err;
 }
 EXPORT_SYMBOL_GPL(__register_bpf_struct_ops);
 #endif
 
 bool btf_param_match_suffix(const struct btf *btf,
                             const struct btf_param *arg,
                             const char *suffix)
 {
         int suffix_len = strlen(suffix), len;
         const char *param_name;
 
         /* In the future, this can be ported to use BTF tagging */
         param_name = btf_name_by_offset(btf, arg->name_off);
         if (str_is_empty(param_name))
                 return false;
         len = strlen(param_name);
         if (len <= suffix_len)
                 return false;
         param_name += len - suffix_len;
         return !strncmp(param_name, suffix, suffix_len);
 }