1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Watchdog support on powerpc systems. |
4 | * |
5 | * Copyright 2017, IBM Corporation. |
6 | * |
7 | * This uses code from arch/sparc/kernel/nmi.c and kernel/watchdog.c |
8 | */ |
9 | |
10 | #define pr_fmt(fmt) "watchdog: " fmt |
11 | |
12 | #include <linux/kernel.h> |
13 | #include <linux/param.h> |
14 | #include <linux/init.h> |
15 | #include <linux/percpu.h> |
16 | #include <linux/cpu.h> |
17 | #include <linux/nmi.h> |
18 | #include <linux/module.h> |
19 | #include <linux/export.h> |
20 | #include <linux/kprobes.h> |
21 | #include <linux/hardirq.h> |
22 | #include <linux/reboot.h> |
23 | #include <linux/slab.h> |
24 | #include <linux/kdebug.h> |
25 | #include <linux/sched/debug.h> |
26 | #include <linux/delay.h> |
27 | #include <linux/processor.h> |
28 | #include <linux/smp.h> |
29 | |
30 | #include <asm/interrupt.h> |
31 | #include <asm/paca.h> |
32 | #include <asm/nmi.h> |
33 | |
34 | /* |
35 | * The powerpc watchdog ensures that each CPU is able to service timers. |
36 | * The watchdog sets up a simple timer on each CPU to run once per timer |
37 | * period, and updates a per-cpu timestamp and a "pending" cpumask. This is |
38 | * the heartbeat. |
39 | * |
40 | * Then there are two systems to check that the heartbeat is still running. |
41 | * The local soft-NMI, and the SMP checker. |
42 | * |
43 | * The soft-NMI checker can detect lockups on the local CPU. When interrupts |
44 | * are disabled with local_irq_disable(), platforms that use soft-masking |
45 | * can leave hardware interrupts enabled and handle them with a masked |
46 | * interrupt handler. The masked handler can send the timer interrupt to the |
47 | * watchdog's soft_nmi_interrupt(), which appears to Linux as an NMI |
48 | * interrupt, and can be used to detect CPUs stuck with IRQs disabled. |
49 | * |
50 | * The soft-NMI checker will compare the heartbeat timestamp for this CPU |
51 | * with the current time, and take action if the difference exceeds the |
52 | * watchdog threshold. |
53 | * |
54 | * The limitation of the soft-NMI watchdog is that it does not work when |
55 | * interrupts are hard disabled or otherwise not being serviced. This is |
56 | * solved by also having a SMP watchdog where all CPUs check all other |
57 | * CPUs heartbeat. |
58 | * |
59 | * The SMP checker can detect lockups on other CPUs. A global "pending" |
60 | * cpumask is kept, containing all CPUs which enable the watchdog. Each |
61 | * CPU clears their pending bit in their heartbeat timer. When the bitmask |
62 | * becomes empty, the last CPU to clear its pending bit updates a global |
63 | * timestamp and refills the pending bitmask. |
64 | * |
65 | * In the heartbeat timer, if any CPU notices that the global timestamp has |
66 | * not been updated for a period exceeding the watchdog threshold, then it |
67 | * means the CPU(s) with their bit still set in the pending mask have had |
68 | * their heartbeat stop, and action is taken. |
69 | * |
70 | * Some platforms implement true NMI IPIs, which can be used by the SMP |
71 | * watchdog to detect an unresponsive CPU and pull it out of its stuck |
72 | * state with the NMI IPI, to get crash/debug data from it. This way the |
73 | * SMP watchdog can detect hardware interrupts off lockups. |
74 | */ |
75 | |
76 | static cpumask_t wd_cpus_enabled __read_mostly; |
77 | |
78 | static u64 wd_panic_timeout_tb __read_mostly; /* timebase ticks until panic */ |
79 | static u64 wd_smp_panic_timeout_tb __read_mostly; /* panic other CPUs */ |
80 | |
81 | static u64 wd_timer_period_ms __read_mostly; /* interval between heartbeat */ |
82 | |
83 | static DEFINE_PER_CPU(struct hrtimer, wd_hrtimer); |
84 | static DEFINE_PER_CPU(u64, wd_timer_tb); |
85 | |
86 | /* SMP checker bits */ |
87 | static unsigned long __wd_smp_lock; |
88 | static unsigned long __wd_reporting; |
89 | static unsigned long __wd_nmi_output; |
90 | static cpumask_t wd_smp_cpus_pending; |
91 | static cpumask_t wd_smp_cpus_stuck; |
92 | static u64 wd_smp_last_reset_tb; |
93 | |
94 | #ifdef CONFIG_PPC_PSERIES |
95 | static u64 wd_timeout_pct; |
96 | #endif |
97 | |
98 | /* |
99 | * Try to take the exclusive watchdog action / NMI IPI / printing lock. |
100 | * wd_smp_lock must be held. If this fails, we should return and wait |
101 | * for the watchdog to kick in again (or another CPU to trigger it). |
102 | * |
103 | * Importantly, if hardlockup_panic is set, wd_try_report failure should |
104 | * not delay the panic, because whichever other CPU is reporting will |
105 | * call panic. |
106 | */ |
107 | static bool wd_try_report(void) |
108 | { |
109 | if (__wd_reporting) |
110 | return false; |
111 | __wd_reporting = 1; |
112 | return true; |
113 | } |
114 | |
115 | /* End printing after successful wd_try_report. wd_smp_lock not required. */ |
116 | static void wd_end_reporting(void) |
117 | { |
118 | smp_mb(); /* End printing "critical section" */ |
119 | WARN_ON_ONCE(__wd_reporting == 0); |
120 | WRITE_ONCE(__wd_reporting, 0); |
121 | } |
122 | |
123 | static inline void wd_smp_lock(unsigned long *flags) |
124 | { |
125 | /* |
126 | * Avoid locking layers if possible. |
127 | * This may be called from low level interrupt handlers at some |
128 | * point in future. |
129 | */ |
130 | raw_local_irq_save(*flags); |
131 | hard_irq_disable(); /* Make it soft-NMI safe */ |
132 | while (unlikely(test_and_set_bit_lock(0, &__wd_smp_lock))) { |
133 | raw_local_irq_restore(*flags); |
134 | spin_until_cond(!test_bit(0, &__wd_smp_lock)); |
135 | raw_local_irq_save(*flags); |
136 | hard_irq_disable(); |
137 | } |
138 | } |
139 | |
140 | static inline void wd_smp_unlock(unsigned long *flags) |
141 | { |
142 | clear_bit_unlock(nr: 0, addr: &__wd_smp_lock); |
143 | raw_local_irq_restore(*flags); |
144 | } |
145 | |
146 | static void wd_lockup_ipi(struct pt_regs *regs) |
147 | { |
148 | int cpu = raw_smp_processor_id(); |
149 | u64 tb = get_tb(); |
150 | |
151 | pr_emerg("CPU %d Hard LOCKUP\n" , cpu); |
152 | pr_emerg("CPU %d TB:%lld, last heartbeat TB:%lld (%lldms ago)\n" , |
153 | cpu, tb, per_cpu(wd_timer_tb, cpu), |
154 | tb_to_ns(tb - per_cpu(wd_timer_tb, cpu)) / 1000000); |
155 | print_modules(); |
156 | print_irqtrace_events(current); |
157 | if (regs) |
158 | show_regs(regs); |
159 | else |
160 | dump_stack(); |
161 | |
162 | /* |
163 | * __wd_nmi_output must be set after we printk from NMI context. |
164 | * |
165 | * printk from NMI context defers printing to the console to irq_work. |
166 | * If that NMI was taken in some code that is hard-locked, then irqs |
167 | * are disabled so irq_work will never fire. That can result in the |
168 | * hard lockup messages being delayed (indefinitely, until something |
169 | * else kicks the console drivers). |
170 | * |
171 | * Setting __wd_nmi_output will cause another CPU to notice and kick |
172 | * the console drivers for us. |
173 | * |
174 | * xchg is not needed here (it could be a smp_mb and store), but xchg |
175 | * gives the memory ordering and atomicity required. |
176 | */ |
177 | xchg(&__wd_nmi_output, 1); |
178 | |
179 | /* Do not panic from here because that can recurse into NMI IPI layer */ |
180 | } |
181 | |
182 | static bool set_cpu_stuck(int cpu) |
183 | { |
184 | cpumask_set_cpu(cpu, dstp: &wd_smp_cpus_stuck); |
185 | cpumask_clear_cpu(cpu, dstp: &wd_smp_cpus_pending); |
186 | /* |
187 | * See wd_smp_clear_cpu_pending() |
188 | */ |
189 | smp_mb(); |
190 | if (cpumask_empty(srcp: &wd_smp_cpus_pending)) { |
191 | wd_smp_last_reset_tb = get_tb(); |
192 | cpumask_andnot(dstp: &wd_smp_cpus_pending, |
193 | src1p: &wd_cpus_enabled, |
194 | src2p: &wd_smp_cpus_stuck); |
195 | return true; |
196 | } |
197 | return false; |
198 | } |
199 | |
200 | static void watchdog_smp_panic(int cpu) |
201 | { |
202 | static cpumask_t wd_smp_cpus_ipi; // protected by reporting |
203 | unsigned long flags; |
204 | u64 tb, last_reset; |
205 | int c; |
206 | |
207 | wd_smp_lock(flags: &flags); |
208 | /* Double check some things under lock */ |
209 | tb = get_tb(); |
210 | last_reset = wd_smp_last_reset_tb; |
211 | if ((s64)(tb - last_reset) < (s64)wd_smp_panic_timeout_tb) |
212 | goto out; |
213 | if (cpumask_test_cpu(cpu, cpumask: &wd_smp_cpus_pending)) |
214 | goto out; |
215 | if (!wd_try_report()) |
216 | goto out; |
217 | for_each_online_cpu(c) { |
218 | if (!cpumask_test_cpu(cpu: c, cpumask: &wd_smp_cpus_pending)) |
219 | continue; |
220 | if (c == cpu) |
221 | continue; // should not happen |
222 | |
223 | __cpumask_set_cpu(cpu: c, dstp: &wd_smp_cpus_ipi); |
224 | if (set_cpu_stuck(c)) |
225 | break; |
226 | } |
227 | if (cpumask_empty(srcp: &wd_smp_cpus_ipi)) { |
228 | wd_end_reporting(); |
229 | goto out; |
230 | } |
231 | wd_smp_unlock(flags: &flags); |
232 | |
233 | pr_emerg("CPU %d detected hard LOCKUP on other CPUs %*pbl\n" , |
234 | cpu, cpumask_pr_args(&wd_smp_cpus_ipi)); |
235 | pr_emerg("CPU %d TB:%lld, last SMP heartbeat TB:%lld (%lldms ago)\n" , |
236 | cpu, tb, last_reset, tb_to_ns(tb - last_reset) / 1000000); |
237 | |
238 | if (!sysctl_hardlockup_all_cpu_backtrace) { |
239 | /* |
240 | * Try to trigger the stuck CPUs, unless we are going to |
241 | * get a backtrace on all of them anyway. |
242 | */ |
243 | for_each_cpu(c, &wd_smp_cpus_ipi) { |
244 | smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000); |
245 | __cpumask_clear_cpu(cpu: c, dstp: &wd_smp_cpus_ipi); |
246 | } |
247 | } else { |
248 | trigger_allbutcpu_cpu_backtrace(exclude_cpu: cpu); |
249 | cpumask_clear(dstp: &wd_smp_cpus_ipi); |
250 | } |
251 | |
252 | if (hardlockup_panic) |
253 | nmi_panic(NULL, msg: "Hard LOCKUP" ); |
254 | |
255 | wd_end_reporting(); |
256 | |
257 | return; |
258 | |
259 | out: |
260 | wd_smp_unlock(flags: &flags); |
261 | } |
262 | |
263 | static void wd_smp_clear_cpu_pending(int cpu) |
264 | { |
265 | if (!cpumask_test_cpu(cpu, cpumask: &wd_smp_cpus_pending)) { |
266 | if (unlikely(cpumask_test_cpu(cpu, &wd_smp_cpus_stuck))) { |
267 | struct pt_regs *regs = get_irq_regs(); |
268 | unsigned long flags; |
269 | |
270 | pr_emerg("CPU %d became unstuck TB:%lld\n" , |
271 | cpu, get_tb()); |
272 | print_irqtrace_events(current); |
273 | if (regs) |
274 | show_regs(regs); |
275 | else |
276 | dump_stack(); |
277 | |
278 | wd_smp_lock(flags: &flags); |
279 | cpumask_clear_cpu(cpu, dstp: &wd_smp_cpus_stuck); |
280 | wd_smp_unlock(flags: &flags); |
281 | } else { |
282 | /* |
283 | * The last CPU to clear pending should have reset the |
284 | * watchdog so we generally should not find it empty |
285 | * here if our CPU was clear. However it could happen |
286 | * due to a rare race with another CPU taking the |
287 | * last CPU out of the mask concurrently. |
288 | * |
289 | * We can't add a warning for it. But just in case |
290 | * there is a problem with the watchdog that is causing |
291 | * the mask to not be reset, try to kick it along here. |
292 | */ |
293 | if (unlikely(cpumask_empty(&wd_smp_cpus_pending))) |
294 | goto none_pending; |
295 | } |
296 | return; |
297 | } |
298 | |
299 | /* |
300 | * All other updates to wd_smp_cpus_pending are performed under |
301 | * wd_smp_lock. All of them are atomic except the case where the |
302 | * mask becomes empty and is reset. This will not happen here because |
303 | * cpu was tested to be in the bitmap (above), and a CPU only clears |
304 | * its own bit. _Except_ in the case where another CPU has detected a |
305 | * hard lockup on our CPU and takes us out of the pending mask. So in |
306 | * normal operation there will be no race here, no problem. |
307 | * |
308 | * In the lockup case, this atomic clear-bit vs a store that refills |
309 | * other bits in the accessed word wll not be a problem. The bit clear |
310 | * is atomic so it will not cause the store to get lost, and the store |
311 | * will never set this bit so it will not overwrite the bit clear. The |
312 | * only way for a stuck CPU to return to the pending bitmap is to |
313 | * become unstuck itself. |
314 | */ |
315 | cpumask_clear_cpu(cpu, dstp: &wd_smp_cpus_pending); |
316 | |
317 | /* |
318 | * Order the store to clear pending with the load(s) to check all |
319 | * words in the pending mask to check they are all empty. This orders |
320 | * with the same barrier on another CPU. This prevents two CPUs |
321 | * clearing the last 2 pending bits, but neither seeing the other's |
322 | * store when checking if the mask is empty, and missing an empty |
323 | * mask, which ends with a false positive. |
324 | */ |
325 | smp_mb(); |
326 | if (cpumask_empty(srcp: &wd_smp_cpus_pending)) { |
327 | unsigned long flags; |
328 | |
329 | none_pending: |
330 | /* |
331 | * Double check under lock because more than one CPU could see |
332 | * a clear mask with the lockless check after clearing their |
333 | * pending bits. |
334 | */ |
335 | wd_smp_lock(flags: &flags); |
336 | if (cpumask_empty(srcp: &wd_smp_cpus_pending)) { |
337 | wd_smp_last_reset_tb = get_tb(); |
338 | cpumask_andnot(dstp: &wd_smp_cpus_pending, |
339 | src1p: &wd_cpus_enabled, |
340 | src2p: &wd_smp_cpus_stuck); |
341 | } |
342 | wd_smp_unlock(flags: &flags); |
343 | } |
344 | } |
345 | |
346 | static void watchdog_timer_interrupt(int cpu) |
347 | { |
348 | u64 tb = get_tb(); |
349 | |
350 | per_cpu(wd_timer_tb, cpu) = tb; |
351 | |
352 | wd_smp_clear_cpu_pending(cpu); |
353 | |
354 | if ((s64)(tb - wd_smp_last_reset_tb) >= (s64)wd_smp_panic_timeout_tb) |
355 | watchdog_smp_panic(cpu); |
356 | |
357 | if (__wd_nmi_output && xchg(&__wd_nmi_output, 0)) { |
358 | /* |
359 | * Something has called printk from NMI context. It might be |
360 | * stuck, so this triggers a flush that will get that |
361 | * printk output to the console. |
362 | * |
363 | * See wd_lockup_ipi. |
364 | */ |
365 | printk_trigger_flush(); |
366 | } |
367 | } |
368 | |
369 | DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt) |
370 | { |
371 | unsigned long flags; |
372 | int cpu = raw_smp_processor_id(); |
373 | u64 tb; |
374 | |
375 | /* should only arrive from kernel, with irqs disabled */ |
376 | WARN_ON_ONCE(!arch_irq_disabled_regs(regs)); |
377 | |
378 | if (!cpumask_test_cpu(cpu, cpumask: &wd_cpus_enabled)) |
379 | return 0; |
380 | |
381 | __this_cpu_inc(irq_stat.soft_nmi_irqs); |
382 | |
383 | tb = get_tb(); |
384 | if (tb - per_cpu(wd_timer_tb, cpu) >= wd_panic_timeout_tb) { |
385 | /* |
386 | * Taking wd_smp_lock here means it is a soft-NMI lock, which |
387 | * means we can't take any regular or irqsafe spin locks while |
388 | * holding this lock. This is why timers can't printk while |
389 | * holding the lock. |
390 | */ |
391 | wd_smp_lock(flags: &flags); |
392 | if (cpumask_test_cpu(cpu, cpumask: &wd_smp_cpus_stuck)) { |
393 | wd_smp_unlock(flags: &flags); |
394 | return 0; |
395 | } |
396 | if (!wd_try_report()) { |
397 | wd_smp_unlock(flags: &flags); |
398 | /* Couldn't report, try again in 100ms */ |
399 | mtspr(SPRN_DEC, 100 * tb_ticks_per_usec * 1000); |
400 | return 0; |
401 | } |
402 | |
403 | set_cpu_stuck(cpu); |
404 | |
405 | wd_smp_unlock(flags: &flags); |
406 | |
407 | pr_emerg("CPU %d self-detected hard LOCKUP @ %pS\n" , |
408 | cpu, (void *)regs->nip); |
409 | pr_emerg("CPU %d TB:%lld, last heartbeat TB:%lld (%lldms ago)\n" , |
410 | cpu, tb, per_cpu(wd_timer_tb, cpu), |
411 | tb_to_ns(tb - per_cpu(wd_timer_tb, cpu)) / 1000000); |
412 | print_modules(); |
413 | print_irqtrace_events(current); |
414 | show_regs(regs); |
415 | |
416 | xchg(&__wd_nmi_output, 1); // see wd_lockup_ipi |
417 | |
418 | if (sysctl_hardlockup_all_cpu_backtrace) |
419 | trigger_allbutcpu_cpu_backtrace(exclude_cpu: cpu); |
420 | |
421 | if (hardlockup_panic) |
422 | nmi_panic(regs, "Hard LOCKUP" ); |
423 | |
424 | wd_end_reporting(); |
425 | } |
426 | /* |
427 | * We are okay to change DEC in soft_nmi_interrupt because the masked |
428 | * handler has marked a DEC as pending, so the timer interrupt will be |
429 | * replayed as soon as local irqs are enabled again. |
430 | */ |
431 | if (wd_panic_timeout_tb < 0x7fffffff) |
432 | mtspr(SPRN_DEC, wd_panic_timeout_tb); |
433 | |
434 | return 0; |
435 | } |
436 | |
437 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) |
438 | { |
439 | int cpu = smp_processor_id(); |
440 | |
441 | if (!(watchdog_enabled & WATCHDOG_HARDLOCKUP_ENABLED)) |
442 | return HRTIMER_NORESTART; |
443 | |
444 | if (!cpumask_test_cpu(cpu, cpumask: &watchdog_cpumask)) |
445 | return HRTIMER_NORESTART; |
446 | |
447 | watchdog_timer_interrupt(cpu); |
448 | |
449 | hrtimer_forward_now(timer: hrtimer, interval: ms_to_ktime(ms: wd_timer_period_ms)); |
450 | |
451 | return HRTIMER_RESTART; |
452 | } |
453 | |
454 | void arch_touch_nmi_watchdog(void) |
455 | { |
456 | unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000; |
457 | int cpu = smp_processor_id(); |
458 | u64 tb; |
459 | |
460 | if (!cpumask_test_cpu(cpu, cpumask: &watchdog_cpumask)) |
461 | return; |
462 | |
463 | tb = get_tb(); |
464 | if (tb - per_cpu(wd_timer_tb, cpu) >= ticks) { |
465 | per_cpu(wd_timer_tb, cpu) = tb; |
466 | wd_smp_clear_cpu_pending(cpu); |
467 | } |
468 | } |
469 | EXPORT_SYMBOL(arch_touch_nmi_watchdog); |
470 | |
471 | static void start_watchdog(void *arg) |
472 | { |
473 | struct hrtimer *hrtimer = this_cpu_ptr(&wd_hrtimer); |
474 | int cpu = smp_processor_id(); |
475 | unsigned long flags; |
476 | |
477 | if (cpumask_test_cpu(cpu, cpumask: &wd_cpus_enabled)) { |
478 | WARN_ON(1); |
479 | return; |
480 | } |
481 | |
482 | if (!(watchdog_enabled & WATCHDOG_HARDLOCKUP_ENABLED)) |
483 | return; |
484 | |
485 | if (!cpumask_test_cpu(cpu, cpumask: &watchdog_cpumask)) |
486 | return; |
487 | |
488 | wd_smp_lock(flags: &flags); |
489 | cpumask_set_cpu(cpu, dstp: &wd_cpus_enabled); |
490 | if (cpumask_weight(srcp: &wd_cpus_enabled) == 1) { |
491 | cpumask_set_cpu(cpu, dstp: &wd_smp_cpus_pending); |
492 | wd_smp_last_reset_tb = get_tb(); |
493 | } |
494 | wd_smp_unlock(flags: &flags); |
495 | |
496 | *this_cpu_ptr(&wd_timer_tb) = get_tb(); |
497 | |
498 | hrtimer_init(timer: hrtimer, CLOCK_MONOTONIC, mode: HRTIMER_MODE_REL); |
499 | hrtimer->function = watchdog_timer_fn; |
500 | hrtimer_start(timer: hrtimer, tim: ms_to_ktime(ms: wd_timer_period_ms), |
501 | mode: HRTIMER_MODE_REL_PINNED); |
502 | } |
503 | |
504 | static int start_watchdog_on_cpu(unsigned int cpu) |
505 | { |
506 | return smp_call_function_single(cpuid: cpu, func: start_watchdog, NULL, wait: true); |
507 | } |
508 | |
509 | static void stop_watchdog(void *arg) |
510 | { |
511 | struct hrtimer *hrtimer = this_cpu_ptr(&wd_hrtimer); |
512 | int cpu = smp_processor_id(); |
513 | unsigned long flags; |
514 | |
515 | if (!cpumask_test_cpu(cpu, cpumask: &wd_cpus_enabled)) |
516 | return; /* Can happen in CPU unplug case */ |
517 | |
518 | hrtimer_cancel(timer: hrtimer); |
519 | |
520 | wd_smp_lock(flags: &flags); |
521 | cpumask_clear_cpu(cpu, dstp: &wd_cpus_enabled); |
522 | wd_smp_unlock(flags: &flags); |
523 | |
524 | wd_smp_clear_cpu_pending(cpu); |
525 | } |
526 | |
527 | static int stop_watchdog_on_cpu(unsigned int cpu) |
528 | { |
529 | return smp_call_function_single(cpuid: cpu, func: stop_watchdog, NULL, wait: true); |
530 | } |
531 | |
532 | static void watchdog_calc_timeouts(void) |
533 | { |
534 | u64 threshold = watchdog_thresh; |
535 | |
536 | #ifdef CONFIG_PPC_PSERIES |
537 | threshold += (READ_ONCE(wd_timeout_pct) * threshold) / 100; |
538 | #endif |
539 | |
540 | wd_panic_timeout_tb = threshold * ppc_tb_freq; |
541 | |
542 | /* Have the SMP detector trigger a bit later */ |
543 | wd_smp_panic_timeout_tb = wd_panic_timeout_tb * 3 / 2; |
544 | |
545 | /* 2/5 is the factor that the perf based detector uses */ |
546 | wd_timer_period_ms = watchdog_thresh * 1000 * 2 / 5; |
547 | } |
548 | |
549 | void watchdog_hardlockup_stop(void) |
550 | { |
551 | int cpu; |
552 | |
553 | for_each_cpu(cpu, &wd_cpus_enabled) |
554 | stop_watchdog_on_cpu(cpu); |
555 | } |
556 | |
557 | void watchdog_hardlockup_start(void) |
558 | { |
559 | int cpu; |
560 | |
561 | watchdog_calc_timeouts(); |
562 | for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask) |
563 | start_watchdog_on_cpu(cpu); |
564 | } |
565 | |
566 | /* |
567 | * Invoked from core watchdog init. |
568 | */ |
569 | int __init watchdog_hardlockup_probe(void) |
570 | { |
571 | int err; |
572 | |
573 | err = cpuhp_setup_state_nocalls(state: CPUHP_AP_ONLINE_DYN, |
574 | name: "powerpc/watchdog:online" , |
575 | startup: start_watchdog_on_cpu, |
576 | teardown: stop_watchdog_on_cpu); |
577 | if (err < 0) { |
578 | pr_warn("could not be initialized" ); |
579 | return err; |
580 | } |
581 | return 0; |
582 | } |
583 | |
584 | #ifdef CONFIG_PPC_PSERIES |
585 | void watchdog_hardlockup_set_timeout_pct(u64 pct) |
586 | { |
587 | pr_info("Set the NMI watchdog timeout factor to %llu%%\n" , pct); |
588 | WRITE_ONCE(wd_timeout_pct, pct); |
589 | lockup_detector_reconfigure(); |
590 | } |
591 | #endif |
592 | |