Merge tag 'for-5.16/block-2021-11-09' of git://git.kernel.dk/linux-block
[linux-2.6-microblaze.git] / kernel / watchdog.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Detect hard and soft lockups on a system
4  *
5  * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
6  *
7  * Note: Most of this code is borrowed heavily from the original softlockup
8  * detector, so thanks to Ingo for the initial implementation.
9  * Some chunks also taken from the old x86-specific nmi watchdog code, thanks
10  * to those contributors as well.
11  */
12
13 #define pr_fmt(fmt) "watchdog: " fmt
14
15 #include <linux/mm.h>
16 #include <linux/cpu.h>
17 #include <linux/nmi.h>
18 #include <linux/init.h>
19 #include <linux/module.h>
20 #include <linux/sysctl.h>
21 #include <linux/tick.h>
22 #include <linux/sched/clock.h>
23 #include <linux/sched/debug.h>
24 #include <linux/sched/isolation.h>
25 #include <linux/stop_machine.h>
26
27 #include <asm/irq_regs.h>
28 #include <linux/kvm_para.h>
29
30 static DEFINE_MUTEX(watchdog_mutex);
31
32 #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
33 # define WATCHDOG_DEFAULT       (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED)
34 # define NMI_WATCHDOG_DEFAULT   1
35 #else
36 # define WATCHDOG_DEFAULT       (SOFT_WATCHDOG_ENABLED)
37 # define NMI_WATCHDOG_DEFAULT   0
38 #endif
39
40 unsigned long __read_mostly watchdog_enabled;
41 int __read_mostly watchdog_user_enabled = 1;
42 int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT;
43 int __read_mostly soft_watchdog_user_enabled = 1;
44 int __read_mostly watchdog_thresh = 10;
45 static int __read_mostly nmi_watchdog_available;
46
47 struct cpumask watchdog_cpumask __read_mostly;
48 unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
49
50 #ifdef CONFIG_HARDLOCKUP_DETECTOR
51
52 # ifdef CONFIG_SMP
53 int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
54 # endif /* CONFIG_SMP */
55
56 /*
57  * Should we panic when a soft-lockup or hard-lockup occurs:
58  */
59 unsigned int __read_mostly hardlockup_panic =
60                         CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
61 /*
62  * We may not want to enable hard lockup detection by default in all cases,
63  * for example when running the kernel as a guest on a hypervisor. In these
64  * cases this function can be called to disable hard lockup detection. This
65  * function should only be executed once by the boot processor before the
66  * kernel command line parameters are parsed, because otherwise it is not
67  * possible to override this in hardlockup_panic_setup().
68  */
69 void __init hardlockup_detector_disable(void)
70 {
71         nmi_watchdog_user_enabled = 0;
72 }
73
74 static int __init hardlockup_panic_setup(char *str)
75 {
76         if (!strncmp(str, "panic", 5))
77                 hardlockup_panic = 1;
78         else if (!strncmp(str, "nopanic", 7))
79                 hardlockup_panic = 0;
80         else if (!strncmp(str, "0", 1))
81                 nmi_watchdog_user_enabled = 0;
82         else if (!strncmp(str, "1", 1))
83                 nmi_watchdog_user_enabled = 1;
84         return 1;
85 }
86 __setup("nmi_watchdog=", hardlockup_panic_setup);
87
88 #endif /* CONFIG_HARDLOCKUP_DETECTOR */
89
90 /*
91  * These functions can be overridden if an architecture implements its
92  * own hardlockup detector.
93  *
94  * watchdog_nmi_enable/disable can be implemented to start and stop when
95  * softlockup watchdog start and stop. The arch must select the
96  * SOFTLOCKUP_DETECTOR Kconfig.
97  */
98 int __weak watchdog_nmi_enable(unsigned int cpu)
99 {
100         hardlockup_detector_perf_enable();
101         return 0;
102 }
103
104 void __weak watchdog_nmi_disable(unsigned int cpu)
105 {
106         hardlockup_detector_perf_disable();
107 }
108
109 /* Return 0, if a NMI watchdog is available. Error code otherwise */
110 int __weak __init watchdog_nmi_probe(void)
111 {
112         return hardlockup_detector_perf_init();
113 }
114
115 /**
116  * watchdog_nmi_stop - Stop the watchdog for reconfiguration
117  *
118  * The reconfiguration steps are:
119  * watchdog_nmi_stop();
120  * update_variables();
121  * watchdog_nmi_start();
122  */
123 void __weak watchdog_nmi_stop(void) { }
124
125 /**
126  * watchdog_nmi_start - Start the watchdog after reconfiguration
127  *
128  * Counterpart to watchdog_nmi_stop().
129  *
130  * The following variables have been updated in update_variables() and
131  * contain the currently valid configuration:
132  * - watchdog_enabled
133  * - watchdog_thresh
134  * - watchdog_cpumask
135  */
136 void __weak watchdog_nmi_start(void) { }
137
138 /**
139  * lockup_detector_update_enable - Update the sysctl enable bit
140  *
141  * Caller needs to make sure that the NMI/perf watchdogs are off, so this
142  * can't race with watchdog_nmi_disable().
143  */
144 static void lockup_detector_update_enable(void)
145 {
146         watchdog_enabled = 0;
147         if (!watchdog_user_enabled)
148                 return;
149         if (nmi_watchdog_available && nmi_watchdog_user_enabled)
150                 watchdog_enabled |= NMI_WATCHDOG_ENABLED;
151         if (soft_watchdog_user_enabled)
152                 watchdog_enabled |= SOFT_WATCHDOG_ENABLED;
153 }
154
155 #ifdef CONFIG_SOFTLOCKUP_DETECTOR
156
157 /*
158  * Delay the soflockup report when running a known slow code.
159  * It does _not_ affect the timestamp of the last successdul reschedule.
160  */
161 #define SOFTLOCKUP_DELAY_REPORT ULONG_MAX
162
163 #ifdef CONFIG_SMP
164 int __read_mostly sysctl_softlockup_all_cpu_backtrace;
165 #endif
166
167 static struct cpumask watchdog_allowed_mask __read_mostly;
168
169 /* Global variables, exported for sysctl */
170 unsigned int __read_mostly softlockup_panic =
171                         CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
172
173 static bool softlockup_initialized __read_mostly;
174 static u64 __read_mostly sample_period;
175
176 /* Timestamp taken after the last successful reschedule. */
177 static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
178 /* Timestamp of the last softlockup report. */
179 static DEFINE_PER_CPU(unsigned long, watchdog_report_ts);
180 static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
181 static DEFINE_PER_CPU(bool, softlockup_touch_sync);
182 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
183 static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
184 static unsigned long soft_lockup_nmi_warn;
185
186 static int __init nowatchdog_setup(char *str)
187 {
188         watchdog_user_enabled = 0;
189         return 1;
190 }
191 __setup("nowatchdog", nowatchdog_setup);
192
193 static int __init nosoftlockup_setup(char *str)
194 {
195         soft_watchdog_user_enabled = 0;
196         return 1;
197 }
198 __setup("nosoftlockup", nosoftlockup_setup);
199
200 static int __init watchdog_thresh_setup(char *str)
201 {
202         get_option(&str, &watchdog_thresh);
203         return 1;
204 }
205 __setup("watchdog_thresh=", watchdog_thresh_setup);
206
207 static void __lockup_detector_cleanup(void);
208
209 /*
210  * Hard-lockup warnings should be triggered after just a few seconds. Soft-
211  * lockups can have false positives under extreme conditions. So we generally
212  * want a higher threshold for soft lockups than for hard lockups. So we couple
213  * the thresholds with a factor: we make the soft threshold twice the amount of
214  * time the hard threshold is.
215  */
216 static int get_softlockup_thresh(void)
217 {
218         return watchdog_thresh * 2;
219 }
220
221 /*
222  * Returns seconds, approximately.  We don't need nanosecond
223  * resolution, and we don't need to waste time with a big divide when
224  * 2^30ns == 1.074s.
225  */
226 static unsigned long get_timestamp(void)
227 {
228         return running_clock() >> 30LL;  /* 2^30 ~= 10^9 */
229 }
230
231 static void set_sample_period(void)
232 {
233         /*
234          * convert watchdog_thresh from seconds to ns
235          * the divide by 5 is to give hrtimer several chances (two
236          * or three with the current relation between the soft
237          * and hard thresholds) to increment before the
238          * hardlockup detector generates a warning
239          */
240         sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
241         watchdog_update_hrtimer_threshold(sample_period);
242 }
243
244 static void update_report_ts(void)
245 {
246         __this_cpu_write(watchdog_report_ts, get_timestamp());
247 }
248
249 /* Commands for resetting the watchdog */
250 static void update_touch_ts(void)
251 {
252         __this_cpu_write(watchdog_touch_ts, get_timestamp());
253         update_report_ts();
254 }
255
256 /**
257  * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls
258  *
259  * Call when the scheduler may have stalled for legitimate reasons
260  * preventing the watchdog task from executing - e.g. the scheduler
261  * entering idle state.  This should only be used for scheduler events.
262  * Use touch_softlockup_watchdog() for everything else.
263  */
264 notrace void touch_softlockup_watchdog_sched(void)
265 {
266         /*
267          * Preemption can be enabled.  It doesn't matter which CPU's watchdog
268          * report period gets restarted here, so use the raw_ operation.
269          */
270         raw_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
271 }
272
273 notrace void touch_softlockup_watchdog(void)
274 {
275         touch_softlockup_watchdog_sched();
276         wq_watchdog_touch(raw_smp_processor_id());
277 }
278 EXPORT_SYMBOL(touch_softlockup_watchdog);
279
280 void touch_all_softlockup_watchdogs(void)
281 {
282         int cpu;
283
284         /*
285          * watchdog_mutex cannpt be taken here, as this might be called
286          * from (soft)interrupt context, so the access to
287          * watchdog_allowed_cpumask might race with a concurrent update.
288          *
289          * The watchdog time stamp can race against a concurrent real
290          * update as well, the only side effect might be a cycle delay for
291          * the softlockup check.
292          */
293         for_each_cpu(cpu, &watchdog_allowed_mask) {
294                 per_cpu(watchdog_report_ts, cpu) = SOFTLOCKUP_DELAY_REPORT;
295                 wq_watchdog_touch(cpu);
296         }
297 }
298
299 void touch_softlockup_watchdog_sync(void)
300 {
301         __this_cpu_write(softlockup_touch_sync, true);
302         __this_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
303 }
304
305 static int is_softlockup(unsigned long touch_ts,
306                          unsigned long period_ts,
307                          unsigned long now)
308 {
309         if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
310                 /* Warn about unreasonable delays. */
311                 if (time_after(now, period_ts + get_softlockup_thresh()))
312                         return now - touch_ts;
313         }
314         return 0;
315 }
316
317 /* watchdog detector functions */
318 bool is_hardlockup(void)
319 {
320         unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
321
322         if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
323                 return true;
324
325         __this_cpu_write(hrtimer_interrupts_saved, hrint);
326         return false;
327 }
328
329 static void watchdog_interrupt_count(void)
330 {
331         __this_cpu_inc(hrtimer_interrupts);
332 }
333
334 static DEFINE_PER_CPU(struct completion, softlockup_completion);
335 static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
336
337 /*
338  * The watchdog feed function - touches the timestamp.
339  *
340  * It only runs once every sample_period seconds (4 seconds by
341  * default) to reset the softlockup timestamp. If this gets delayed
342  * for more than 2*watchdog_thresh seconds then the debug-printout
343  * triggers in watchdog_timer_fn().
344  */
345 static int softlockup_fn(void *data)
346 {
347         update_touch_ts();
348         complete(this_cpu_ptr(&softlockup_completion));
349
350         return 0;
351 }
352
353 /* watchdog kicker functions */
354 static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
355 {
356         unsigned long touch_ts, period_ts, now;
357         struct pt_regs *regs = get_irq_regs();
358         int duration;
359         int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
360
361         if (!watchdog_enabled)
362                 return HRTIMER_NORESTART;
363
364         /* kick the hardlockup detector */
365         watchdog_interrupt_count();
366
367         /* kick the softlockup detector */
368         if (completion_done(this_cpu_ptr(&softlockup_completion))) {
369                 reinit_completion(this_cpu_ptr(&softlockup_completion));
370                 stop_one_cpu_nowait(smp_processor_id(),
371                                 softlockup_fn, NULL,
372                                 this_cpu_ptr(&softlockup_stop_work));
373         }
374
375         /* .. and repeat */
376         hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
377
378         /*
379          * Read the current timestamp first. It might become invalid anytime
380          * when a virtual machine is stopped by the host or when the watchog
381          * is touched from NMI.
382          */
383         now = get_timestamp();
384         /*
385          * If a virtual machine is stopped by the host it can look to
386          * the watchdog like a soft lockup. This function touches the watchdog.
387          */
388         kvm_check_and_clear_guest_paused();
389         /*
390          * The stored timestamp is comparable with @now only when not touched.
391          * It might get touched anytime from NMI. Make sure that is_softlockup()
392          * uses the same (valid) value.
393          */
394         period_ts = READ_ONCE(*this_cpu_ptr(&watchdog_report_ts));
395
396         /* Reset the interval when touched by known problematic code. */
397         if (period_ts == SOFTLOCKUP_DELAY_REPORT) {
398                 if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
399                         /*
400                          * If the time stamp was touched atomically
401                          * make sure the scheduler tick is up to date.
402                          */
403                         __this_cpu_write(softlockup_touch_sync, false);
404                         sched_clock_tick();
405                 }
406
407                 update_report_ts();
408                 return HRTIMER_RESTART;
409         }
410
411         /* Check for a softlockup. */
412         touch_ts = __this_cpu_read(watchdog_touch_ts);
413         duration = is_softlockup(touch_ts, period_ts, now);
414         if (unlikely(duration)) {
415                 /*
416                  * Prevent multiple soft-lockup reports if one cpu is already
417                  * engaged in dumping all cpu back traces.
418                  */
419                 if (softlockup_all_cpu_backtrace) {
420                         if (test_and_set_bit_lock(0, &soft_lockup_nmi_warn))
421                                 return HRTIMER_RESTART;
422                 }
423
424                 /* Start period for the next softlockup warning. */
425                 update_report_ts();
426
427                 pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
428                         smp_processor_id(), duration,
429                         current->comm, task_pid_nr(current));
430                 print_modules();
431                 print_irqtrace_events(current);
432                 if (regs)
433                         show_regs(regs);
434                 else
435                         dump_stack();
436
437                 if (softlockup_all_cpu_backtrace) {
438                         trigger_allbutself_cpu_backtrace();
439                         clear_bit_unlock(0, &soft_lockup_nmi_warn);
440                 }
441
442                 add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
443                 if (softlockup_panic)
444                         panic("softlockup: hung tasks");
445         }
446
447         return HRTIMER_RESTART;
448 }
449
450 static void watchdog_enable(unsigned int cpu)
451 {
452         struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
453         struct completion *done = this_cpu_ptr(&softlockup_completion);
454
455         WARN_ON_ONCE(cpu != smp_processor_id());
456
457         init_completion(done);
458         complete(done);
459
460         /*
461          * Start the timer first to prevent the NMI watchdog triggering
462          * before the timer has a chance to fire.
463          */
464         hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
465         hrtimer->function = watchdog_timer_fn;
466         hrtimer_start(hrtimer, ns_to_ktime(sample_period),
467                       HRTIMER_MODE_REL_PINNED_HARD);
468
469         /* Initialize timestamp */
470         update_touch_ts();
471         /* Enable the perf event */
472         if (watchdog_enabled & NMI_WATCHDOG_ENABLED)
473                 watchdog_nmi_enable(cpu);
474 }
475
476 static void watchdog_disable(unsigned int cpu)
477 {
478         struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
479
480         WARN_ON_ONCE(cpu != smp_processor_id());
481
482         /*
483          * Disable the perf event first. That prevents that a large delay
484          * between disabling the timer and disabling the perf event causes
485          * the perf NMI to detect a false positive.
486          */
487         watchdog_nmi_disable(cpu);
488         hrtimer_cancel(hrtimer);
489         wait_for_completion(this_cpu_ptr(&softlockup_completion));
490 }
491
492 static int softlockup_stop_fn(void *data)
493 {
494         watchdog_disable(smp_processor_id());
495         return 0;
496 }
497
498 static void softlockup_stop_all(void)
499 {
500         int cpu;
501
502         if (!softlockup_initialized)
503                 return;
504
505         for_each_cpu(cpu, &watchdog_allowed_mask)
506                 smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false);
507
508         cpumask_clear(&watchdog_allowed_mask);
509 }
510
511 static int softlockup_start_fn(void *data)
512 {
513         watchdog_enable(smp_processor_id());
514         return 0;
515 }
516
517 static void softlockup_start_all(void)
518 {
519         int cpu;
520
521         cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask);
522         for_each_cpu(cpu, &watchdog_allowed_mask)
523                 smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false);
524 }
525
526 int lockup_detector_online_cpu(unsigned int cpu)
527 {
528         if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
529                 watchdog_enable(cpu);
530         return 0;
531 }
532
533 int lockup_detector_offline_cpu(unsigned int cpu)
534 {
535         if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
536                 watchdog_disable(cpu);
537         return 0;
538 }
539
540 static void lockup_detector_reconfigure(void)
541 {
542         cpus_read_lock();
543         watchdog_nmi_stop();
544
545         softlockup_stop_all();
546         set_sample_period();
547         lockup_detector_update_enable();
548         if (watchdog_enabled && watchdog_thresh)
549                 softlockup_start_all();
550
551         watchdog_nmi_start();
552         cpus_read_unlock();
553         /*
554          * Must be called outside the cpus locked section to prevent
555          * recursive locking in the perf code.
556          */
557         __lockup_detector_cleanup();
558 }
559
560 /*
561  * Create the watchdog infrastructure and configure the detector(s).
562  */
563 static __init void lockup_detector_setup(void)
564 {
565         /*
566          * If sysctl is off and watchdog got disabled on the command line,
567          * nothing to do here.
568          */
569         lockup_detector_update_enable();
570
571         if (!IS_ENABLED(CONFIG_SYSCTL) &&
572             !(watchdog_enabled && watchdog_thresh))
573                 return;
574
575         mutex_lock(&watchdog_mutex);
576         lockup_detector_reconfigure();
577         softlockup_initialized = true;
578         mutex_unlock(&watchdog_mutex);
579 }
580
581 #else /* CONFIG_SOFTLOCKUP_DETECTOR */
582 static void lockup_detector_reconfigure(void)
583 {
584         cpus_read_lock();
585         watchdog_nmi_stop();
586         lockup_detector_update_enable();
587         watchdog_nmi_start();
588         cpus_read_unlock();
589 }
590 static inline void lockup_detector_setup(void)
591 {
592         lockup_detector_reconfigure();
593 }
594 #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */
595
596 static void __lockup_detector_cleanup(void)
597 {
598         lockdep_assert_held(&watchdog_mutex);
599         hardlockup_detector_perf_cleanup();
600 }
601
602 /**
603  * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes
604  *
605  * Caller must not hold the cpu hotplug rwsem.
606  */
607 void lockup_detector_cleanup(void)
608 {
609         mutex_lock(&watchdog_mutex);
610         __lockup_detector_cleanup();
611         mutex_unlock(&watchdog_mutex);
612 }
613
614 /**
615  * lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
616  *
617  * Special interface for parisc. It prevents lockup detector warnings from
618  * the default pm_poweroff() function which busy loops forever.
619  */
620 void lockup_detector_soft_poweroff(void)
621 {
622         watchdog_enabled = 0;
623 }
624
625 #ifdef CONFIG_SYSCTL
626
627 /* Propagate any changes to the watchdog infrastructure */
628 static void proc_watchdog_update(void)
629 {
630         /* Remove impossible cpus to keep sysctl output clean. */
631         cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);
632         lockup_detector_reconfigure();
633 }
634
635 /*
636  * common function for watchdog, nmi_watchdog and soft_watchdog parameter
637  *
638  * caller             | table->data points to      | 'which'
639  * -------------------|----------------------------|--------------------------
640  * proc_watchdog      | watchdog_user_enabled      | NMI_WATCHDOG_ENABLED |
641  *                    |                            | SOFT_WATCHDOG_ENABLED
642  * -------------------|----------------------------|--------------------------
643  * proc_nmi_watchdog  | nmi_watchdog_user_enabled  | NMI_WATCHDOG_ENABLED
644  * -------------------|----------------------------|--------------------------
645  * proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED
646  */
647 static int proc_watchdog_common(int which, struct ctl_table *table, int write,
648                                 void *buffer, size_t *lenp, loff_t *ppos)
649 {
650         int err, old, *param = table->data;
651
652         mutex_lock(&watchdog_mutex);
653
654         if (!write) {
655                 /*
656                  * On read synchronize the userspace interface. This is a
657                  * racy snapshot.
658                  */
659                 *param = (watchdog_enabled & which) != 0;
660                 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
661         } else {
662                 old = READ_ONCE(*param);
663                 err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
664                 if (!err && old != READ_ONCE(*param))
665                         proc_watchdog_update();
666         }
667         mutex_unlock(&watchdog_mutex);
668         return err;
669 }
670
671 /*
672  * /proc/sys/kernel/watchdog
673  */
674 int proc_watchdog(struct ctl_table *table, int write,
675                   void *buffer, size_t *lenp, loff_t *ppos)
676 {
677         return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED,
678                                     table, write, buffer, lenp, ppos);
679 }
680
681 /*
682  * /proc/sys/kernel/nmi_watchdog
683  */
684 int proc_nmi_watchdog(struct ctl_table *table, int write,
685                       void *buffer, size_t *lenp, loff_t *ppos)
686 {
687         if (!nmi_watchdog_available && write)
688                 return -ENOTSUPP;
689         return proc_watchdog_common(NMI_WATCHDOG_ENABLED,
690                                     table, write, buffer, lenp, ppos);
691 }
692
693 /*
694  * /proc/sys/kernel/soft_watchdog
695  */
696 int proc_soft_watchdog(struct ctl_table *table, int write,
697                         void *buffer, size_t *lenp, loff_t *ppos)
698 {
699         return proc_watchdog_common(SOFT_WATCHDOG_ENABLED,
700                                     table, write, buffer, lenp, ppos);
701 }
702
703 /*
704  * /proc/sys/kernel/watchdog_thresh
705  */
706 int proc_watchdog_thresh(struct ctl_table *table, int write,
707                          void *buffer, size_t *lenp, loff_t *ppos)
708 {
709         int err, old;
710
711         mutex_lock(&watchdog_mutex);
712
713         old = READ_ONCE(watchdog_thresh);
714         err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
715
716         if (!err && write && old != READ_ONCE(watchdog_thresh))
717                 proc_watchdog_update();
718
719         mutex_unlock(&watchdog_mutex);
720         return err;
721 }
722
723 /*
724  * The cpumask is the mask of possible cpus that the watchdog can run
725  * on, not the mask of cpus it is actually running on.  This allows the
726  * user to specify a mask that will include cpus that have not yet
727  * been brought online, if desired.
728  */
729 int proc_watchdog_cpumask(struct ctl_table *table, int write,
730                           void *buffer, size_t *lenp, loff_t *ppos)
731 {
732         int err;
733
734         mutex_lock(&watchdog_mutex);
735
736         err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
737         if (!err && write)
738                 proc_watchdog_update();
739
740         mutex_unlock(&watchdog_mutex);
741         return err;
742 }
743 #endif /* CONFIG_SYSCTL */
744
745 void __init lockup_detector_init(void)
746 {
747         if (tick_nohz_full_enabled())
748                 pr_info("Disabling watchdog on nohz_full cores by default\n");
749
750         cpumask_copy(&watchdog_cpumask,
751                      housekeeping_cpumask(HK_FLAG_TIMER));
752
753         if (!watchdog_nmi_probe())
754                 nmi_watchdog_available = true;
755         lockup_detector_setup();
756 }