1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 ** SMP Support
4 **
5 ** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
6 ** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
7 ** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
8 **
9 ** Lots of stuff stolen from arch/alpha/kernel/smp.c
10 ** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
11 **
12 ** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
13 ** -grant (1/12/2001)
14 **
15 */
16 #include <linux/types.h>
17 #include <linux/spinlock.h>
18
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/sched/mm.h>
22 #include <linux/init.h>
23 #include <linux/interrupt.h>
24 #include <linux/smp.h>
25 #include <linux/kernel_stat.h>
26 #include <linux/mm.h>
27 #include <linux/err.h>
28 #include <linux/delay.h>
29 #include <linux/bitops.h>
30 #include <linux/ftrace.h>
31 #include <linux/cpu.h>
32 #include <linux/kgdb.h>
33 #include <linux/sched/hotplug.h>
34
35 #include <linux/atomic.h>
36 #include <asm/current.h>
37 #include <asm/delay.h>
38 #include <asm/tlbflush.h>
39
40 #include <asm/io.h>
41 #include <asm/irq.h> /* for CPU_IRQ_REGION and friends */
42 #include <asm/mmu_context.h>
43 #include <asm/page.h>
44 #include <asm/processor.h>
45 #include <asm/ptrace.h>
46 #include <asm/unistd.h>
47 #include <asm/cacheflush.h>
48
49 #undef DEBUG_SMP
50 #ifdef DEBUG_SMP
51 static int smp_debug_lvl = 0;
52 #define smp_debug(lvl, printargs...) \
53 if (lvl >= smp_debug_lvl) \
54 printk(printargs);
55 #else
56 #define smp_debug(lvl, ...) do { } while(0)
57 #endif /* DEBUG_SMP */
58
59 volatile struct task_struct *smp_init_current_idle_task;
60
61 /* track which CPU is booting */
62 static volatile int cpu_now_booting;
63
64 static DEFINE_PER_CPU(spinlock_t, ipi_lock);
65
66 enum ipi_message_type {
67 IPI_NOP=0,
68 IPI_RESCHEDULE=1,
69 IPI_CALL_FUNC,
70 IPI_CPU_START,
71 IPI_CPU_STOP,
72 IPI_CPU_TEST,
73 #ifdef CONFIG_KGDB
74 IPI_ENTER_KGDB,
75 #endif
76 };
77
78
79 /********** SMP inter processor interrupt and communication routines */
80
81 #undef PER_CPU_IRQ_REGION
82 #ifdef PER_CPU_IRQ_REGION
83 /* XXX REVISIT Ignore for now.
84 ** *May* need this "hook" to register IPI handler
85 ** once we have perCPU ExtIntr switch tables.
86 */
87 static void
88 ipi_init(int cpuid)
89 {
90 #error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
91
92 if(cpu_online(cpuid) )
93 {
94 switch_to_idle_task(current);
95 }
96
97 return;
98 }
99 #endif
100
101
102 /*
103 ** Yoink this CPU from the runnable list...
104 **
105 */
106 static void
107 halt_processor(void)
108 {
109 /* REVISIT : redirect I/O Interrupts to another CPU? */
110 /* REVISIT : does PM *know* this CPU isn't available? */
111 set_cpu_online(smp_processor_id(), false);
112 local_irq_disable();
113 __pdc_cpu_rendezvous();
114 for (;;)
115 ;
116 }
117
118
119 irqreturn_t __irq_entry
120 ipi_interrupt(int irq, void *dev_id)
121 {
122 int this_cpu = smp_processor_id();
123 struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
124 unsigned long ops;
125 unsigned long flags;
126
127 for (;;) {
128 spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
129 spin_lock_irqsave(lock, flags);
130 ops = p->pending_ipi;
131 p->pending_ipi = 0;
132 spin_unlock_irqrestore(lock, flags);
133
134 mb(); /* Order bit clearing and data access. */
135
136 if (!ops)
137 break;
138
139 while (ops) {
140 unsigned long which = ffz(~ops);
141
142 ops &= ~(1 << which);
143
144 switch (which) {
145 case IPI_NOP:
146 smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
147 break;
148
149 case IPI_RESCHEDULE:
150 smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
151 inc_irq_stat(irq_resched_count);
152 scheduler_ipi();
153 break;
154
155 case IPI_CALL_FUNC:
156 smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
157 inc_irq_stat(irq_call_count);
158 generic_smp_call_function_interrupt();
159 break;
160
161 case IPI_CPU_START:
162 smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
163 break;
164
165 case IPI_CPU_STOP:
166 smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
167 halt_processor();
168 break;
169
170 case IPI_CPU_TEST:
171 smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
172 break;
173 #ifdef CONFIG_KGDB
174 case IPI_ENTER_KGDB:
175 smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
176 kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
177 break;
178 #endif
179 default:
180 printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
181 this_cpu, which);
182 return IRQ_NONE;
183 } /* Switch */
184
185 /* before doing more, let in any pending interrupts */
186 if (ops) {
187 local_irq_enable();
188 local_irq_disable();
189 }
190 } /* while (ops) */
191 }
192 return IRQ_HANDLED;
193 }
194
195
196 static inline void
197 ipi_send(int cpu, enum ipi_message_type op)
198 {
199 struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
200 spinlock_t *lock = &per_cpu(ipi_lock, cpu);
201 unsigned long flags;
202
203 spin_lock_irqsave(lock, flags);
204 p->pending_ipi |= 1 << op;
205 gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
206 spin_unlock_irqrestore(lock, flags);
207 }
208
209 static void
210 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
211 {
212 int cpu;
213
214 for_each_cpu(cpu, mask)
215 ipi_send(cpu, op);
216 }
217
218 static inline void
219 send_IPI_single(int dest_cpu, enum ipi_message_type op)
220 {
221 BUG_ON(dest_cpu == NO_PROC_ID);
222
223 ipi_send(dest_cpu, op);
224 }
225
226 static inline void
227 send_IPI_allbutself(enum ipi_message_type op)
228 {
229 int i;
230
231 preempt_disable();
232 for_each_online_cpu(i) {
233 if (i != smp_processor_id())
234 send_IPI_single(i, op);
235 }
236 preempt_enable();
237 }
238
239 #ifdef CONFIG_KGDB
240 void kgdb_roundup_cpus(void)
241 {
242 send_IPI_allbutself(IPI_ENTER_KGDB);
243 }
244 #endif
245
246 inline void
247 smp_send_stop(void) { send_IPI_allbutself(IPI_CPU_STOP); }
248
249 void
250 arch_smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
251
252 void
253 smp_send_all_nop(void)
254 {
255 send_IPI_allbutself(IPI_NOP);
256 }
257
258 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
259 {
260 send_IPI_mask(mask, IPI_CALL_FUNC);
261 }
262
263 void arch_send_call_function_single_ipi(int cpu)
264 {
265 send_IPI_single(cpu, IPI_CALL_FUNC);
266 }
267
268 /*
269 * Called by secondaries to update state and initialize CPU registers.
270 */
271 static void
272 smp_cpu_init(int cpunum)
273 {
274 /* Set modes and Enable floating point coprocessor */
275 init_per_cpu(cpunum);
276
277 disable_sr_hashing();
278
279 mb();
280
281 /* Well, support 2.4 linux scheme as well. */
282 if (cpu_online(cpunum)) {
283 extern void machine_halt(void); /* arch/parisc.../process.c */
284
285 printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
286 machine_halt();
287 }
288
289 notify_cpu_starting(cpunum);
290
291 set_cpu_online(cpunum, true);
292
293 /* Initialise the idle task for this CPU */
294 mmgrab(&init_mm);
295 current->active_mm = &init_mm;
296 BUG_ON(current->mm);
297 enter_lazy_tlb(&init_mm, current);
298
299 init_IRQ(); /* make sure no IRQs are enabled or pending */
300 start_cpu_itimer();
301 }
302
303
304 /*
305 * Slaves start using C here. Indirectly called from smp_slave_stext.
306 * Do what start_kernel() and main() do for boot strap processor (aka monarch)
307 */
308 void smp_callin(unsigned long pdce_proc)
309 {
310 int slave_id = cpu_now_booting;
311
312 #ifdef CONFIG_64BIT
313 WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
314 | PAGE0->mem_pdc) != pdce_proc);
315 #endif
316
317 smp_cpu_init(slave_id);
318
319 flush_cache_all_local(); /* start with known state */
320 flush_tlb_all_local(NULL);
321
322 local_irq_enable(); /* Interrupts have been off until now */
323
324 cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
325
326 /* NOTREACHED */
327 panic("smp_callin() AAAAaaaaahhhh....\n");
328 }
329
330 /*
331 * Bring one cpu online.
332 */
333 static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
334 {
335 const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
336 long timeout;
337
338 #ifdef CONFIG_HOTPLUG_CPU
339 int i;
340
341 /* reset irq statistics for this CPU */
342 memset(&per_cpu(irq_stat, cpuid), 0, sizeof(irq_cpustat_t));
343 for (i = 0; i < NR_IRQS; i++) {
344 struct irq_desc *desc = irq_to_desc(i);
345
346 if (desc && desc->kstat_irqs)
347 *per_cpu_ptr(desc->kstat_irqs, cpuid) = (struct irqstat) { };
348 }
349 #endif
350
351 /* wait until last booting CPU has started. */
352 while (cpu_now_booting)
353 ;
354
355 /* Let _start know what logical CPU we're booting
356 ** (offset into init_tasks[],cpu_data[])
357 */
358 cpu_now_booting = cpuid;
359
360 /*
361 ** boot strap code needs to know the task address since
362 ** it also contains the process stack.
363 */
364 smp_init_current_idle_task = idle ;
365 mb();
366
367 printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
368
369 /*
370 ** This gets PDC to release the CPU from a very tight loop.
371 **
372 ** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
373 ** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
374 ** is executed after receiving the rendezvous signal (an interrupt to
375 ** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
376 ** contents of memory are valid."
377 */
378 gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
379 mb();
380
381 /*
382 * OK, wait a bit for that CPU to finish staggering about.
383 * Slave will set a bit when it reaches smp_cpu_init().
384 * Once the "monarch CPU" sees the bit change, it can move on.
385 */
386 for (timeout = 0; timeout < 10000; timeout++) {
387 if(cpu_online(cpuid)) {
388 /* Which implies Slave has started up */
389 cpu_now_booting = 0;
390 goto alive ;
391 }
392 udelay(100);
393 barrier();
394 }
395 printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
396 return -1;
397
398 alive:
399 /* Remember the Slave data */
400 smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
401 cpuid, timeout * 100);
402 return 0;
403 }
404
405 void __init smp_prepare_boot_cpu(void)
406 {
407 pr_info("SMP: bootstrap CPU ID is 0\n");
408 }
409
410
411
412 /*
413 ** inventory.c:do_inventory() hasn't yet been run and thus we
414 ** don't 'discover' the additional CPUs until later.
415 */
416 void __init smp_prepare_cpus(unsigned int max_cpus)
417 {
418 int cpu;
419
420 for_each_possible_cpu(cpu)
421 spin_lock_init(&per_cpu(ipi_lock, cpu));
422
423 init_cpu_present(cpumask_of(0));
424 }
425
426
427 void __init smp_cpus_done(unsigned int cpu_max)
428 {
429 }
430
431
432 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
433 {
434 if (cpu_online(cpu))
435 return 0;
436
437 if (num_online_cpus() < nr_cpu_ids &&
438 num_online_cpus() < setup_max_cpus &&
439 smp_boot_one_cpu(cpu, tidle))
440 return -EIO;
441
442 return cpu_online(cpu) ? 0 : -EIO;
443 }
444
445 /*
446 * __cpu_disable runs on the processor to be shutdown.
447 */
448 int __cpu_disable(void)
449 {
450 #ifdef CONFIG_HOTPLUG_CPU
451 unsigned int cpu = smp_processor_id();
452
453 remove_cpu_topology(cpu);
454
455 /*
456 * Take this CPU offline. Once we clear this, we can't return,
457 * and we must not schedule until we're ready to give up the cpu.
458 */
459 set_cpu_online(cpu, false);
460
461 /* Find a new timesync master */
462 if (cpu == time_keeper_id) {
463 time_keeper_id = cpumask_first(cpu_online_mask);
464 pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
465 }
466
467 disable_percpu_irq(IPI_IRQ);
468
469 irq_migrate_all_off_this_cpu();
470
471 flush_cache_all_local();
472 flush_tlb_all_local(NULL);
473
474 /* disable all irqs, including timer irq */
475 local_irq_disable();
476
477 /* wait for next timer irq ... */
478 mdelay(1000/HZ+100);
479
480 /* ... and then clear all pending external irqs */
481 set_eiem(0);
482 mtctl(~0UL, CR_EIRR);
483 mfctl(CR_EIRR);
484 mtctl(0, CR_EIRR);
485 #endif
486 return 0;
487 }
488
489 /*
490 * called on the thread which is asking for a CPU to be shutdown -
491 * waits until shutdown has completed, or it is timed out.
492 */
493 void __cpu_die(unsigned int cpu)
494 {
495 pdc_cpu_rendezvous_lock();
496 }
497
498 void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
499 {
500 pr_info("CPU%u: is shutting down\n", cpu);
501
502 /* set task's state to interruptible sleep */
503 set_current_state(TASK_INTERRUPTIBLE);
504 schedule_timeout((IS_ENABLED(CONFIG_64BIT) ? 8:2) * HZ);
505
506 pdc_cpu_rendezvous_unlock();
507 }
508
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