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Commit | Line | Data |
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58687acb DZ |
1 | /* |
2 | * Detect hard and soft lockups on a system | |
3 | * | |
4 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. | |
5 | * | |
86f5e6a7 FLVC |
6 | * Note: Most of this code is borrowed heavily from the original softlockup |
7 | * detector, so thanks to Ingo for the initial implementation. | |
8 | * Some chunks also taken from the old x86-specific nmi watchdog code, thanks | |
58687acb DZ |
9 | * to those contributors as well. |
10 | */ | |
11 | ||
4501980a AM |
12 | #define pr_fmt(fmt) "NMI watchdog: " fmt |
13 | ||
58687acb DZ |
14 | #include <linux/mm.h> |
15 | #include <linux/cpu.h> | |
16 | #include <linux/nmi.h> | |
17 | #include <linux/init.h> | |
58687acb DZ |
18 | #include <linux/module.h> |
19 | #include <linux/sysctl.h> | |
bcd951cf | 20 | #include <linux/smpboot.h> |
8bd75c77 | 21 | #include <linux/sched/rt.h> |
58687acb DZ |
22 | |
23 | #include <asm/irq_regs.h> | |
5d1c0f4a | 24 | #include <linux/kvm_para.h> |
58687acb DZ |
25 | #include <linux/perf_event.h> |
26 | ||
84d56e66 UO |
27 | /* |
28 | * The run state of the lockup detectors is controlled by the content of the | |
29 | * 'watchdog_enabled' variable. Each lockup detector has its dedicated bit - | |
30 | * bit 0 for the hard lockup detector and bit 1 for the soft lockup detector. | |
31 | * | |
32 | * 'watchdog_user_enabled', 'nmi_watchdog_enabled' and 'soft_watchdog_enabled' | |
33 | * are variables that are only used as an 'interface' between the parameters | |
34 | * in /proc/sys/kernel and the internal state bits in 'watchdog_enabled'. The | |
35 | * 'watchdog_thresh' variable is handled differently because its value is not | |
36 | * boolean, and the lockup detectors are 'suspended' while 'watchdog_thresh' | |
37 | * is equal zero. | |
38 | */ | |
39 | #define NMI_WATCHDOG_ENABLED_BIT 0 | |
40 | #define SOFT_WATCHDOG_ENABLED_BIT 1 | |
41 | #define NMI_WATCHDOG_ENABLED (1 << NMI_WATCHDOG_ENABLED_BIT) | |
42 | #define SOFT_WATCHDOG_ENABLED (1 << SOFT_WATCHDOG_ENABLED_BIT) | |
43 | ||
44 | #ifdef CONFIG_HARDLOCKUP_DETECTOR | |
45 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED|NMI_WATCHDOG_ENABLED; | |
46 | #else | |
47 | static unsigned long __read_mostly watchdog_enabled = SOFT_WATCHDOG_ENABLED; | |
48 | #endif | |
49 | int __read_mostly nmi_watchdog_enabled; | |
50 | int __read_mostly soft_watchdog_enabled; | |
51 | int __read_mostly watchdog_user_enabled; | |
4eec42f3 | 52 | int __read_mostly watchdog_thresh = 10; |
84d56e66 | 53 | |
ed235875 AT |
54 | #ifdef CONFIG_SMP |
55 | int __read_mostly sysctl_softlockup_all_cpu_backtrace; | |
56 | #else | |
57 | #define sysctl_softlockup_all_cpu_backtrace 0 | |
58 | #endif | |
59 | ||
3c00ea82 | 60 | static int __read_mostly watchdog_running; |
0f34c400 | 61 | static u64 __read_mostly sample_period; |
58687acb DZ |
62 | |
63 | static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); | |
64 | static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); | |
65 | static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); | |
66 | static DEFINE_PER_CPU(bool, softlockup_touch_sync); | |
58687acb | 67 | static DEFINE_PER_CPU(bool, soft_watchdog_warn); |
bcd951cf TG |
68 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); |
69 | static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); | |
b1a8de1f | 70 | static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); |
23637d47 | 71 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
cafcd80d DZ |
72 | static DEFINE_PER_CPU(bool, hard_watchdog_warn); |
73 | static DEFINE_PER_CPU(bool, watchdog_nmi_touch); | |
58687acb DZ |
74 | static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); |
75 | static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); | |
76 | #endif | |
ed235875 | 77 | static unsigned long soft_lockup_nmi_warn; |
58687acb | 78 | |
58687acb DZ |
79 | /* boot commands */ |
80 | /* | |
81 | * Should we panic when a soft-lockup or hard-lockup occurs: | |
82 | */ | |
23637d47 | 83 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
fef2c9bc DZ |
84 | static int hardlockup_panic = |
85 | CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; | |
58687acb | 86 | |
6e7458a6 UO |
87 | static bool hardlockup_detector_enabled = true; |
88 | /* | |
89 | * We may not want to enable hard lockup detection by default in all cases, | |
90 | * for example when running the kernel as a guest on a hypervisor. In these | |
91 | * cases this function can be called to disable hard lockup detection. This | |
92 | * function should only be executed once by the boot processor before the | |
93 | * kernel command line parameters are parsed, because otherwise it is not | |
94 | * possible to override this in hardlockup_panic_setup(). | |
95 | */ | |
96 | void watchdog_enable_hardlockup_detector(bool val) | |
97 | { | |
98 | hardlockup_detector_enabled = val; | |
99 | } | |
100 | ||
101 | bool watchdog_hardlockup_detector_is_enabled(void) | |
102 | { | |
103 | return hardlockup_detector_enabled; | |
104 | } | |
105 | ||
58687acb DZ |
106 | static int __init hardlockup_panic_setup(char *str) |
107 | { | |
108 | if (!strncmp(str, "panic", 5)) | |
109 | hardlockup_panic = 1; | |
fef2c9bc DZ |
110 | else if (!strncmp(str, "nopanic", 7)) |
111 | hardlockup_panic = 0; | |
5dc30558 | 112 | else if (!strncmp(str, "0", 1)) |
3c00ea82 | 113 | watchdog_user_enabled = 0; |
6e7458a6 UO |
114 | else if (!strncmp(str, "1", 1) || !strncmp(str, "2", 1)) { |
115 | /* | |
116 | * Setting 'nmi_watchdog=1' or 'nmi_watchdog=2' (legacy option) | |
117 | * has the same effect. | |
118 | */ | |
119 | watchdog_user_enabled = 1; | |
120 | watchdog_enable_hardlockup_detector(true); | |
121 | } | |
58687acb DZ |
122 | return 1; |
123 | } | |
124 | __setup("nmi_watchdog=", hardlockup_panic_setup); | |
125 | #endif | |
126 | ||
127 | unsigned int __read_mostly softlockup_panic = | |
128 | CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; | |
129 | ||
130 | static int __init softlockup_panic_setup(char *str) | |
131 | { | |
132 | softlockup_panic = simple_strtoul(str, NULL, 0); | |
133 | ||
134 | return 1; | |
135 | } | |
136 | __setup("softlockup_panic=", softlockup_panic_setup); | |
137 | ||
138 | static int __init nowatchdog_setup(char *str) | |
139 | { | |
3c00ea82 | 140 | watchdog_user_enabled = 0; |
58687acb DZ |
141 | return 1; |
142 | } | |
143 | __setup("nowatchdog", nowatchdog_setup); | |
144 | ||
145 | /* deprecated */ | |
146 | static int __init nosoftlockup_setup(char *str) | |
147 | { | |
3c00ea82 | 148 | watchdog_user_enabled = 0; |
58687acb DZ |
149 | return 1; |
150 | } | |
151 | __setup("nosoftlockup", nosoftlockup_setup); | |
152 | /* */ | |
ed235875 AT |
153 | #ifdef CONFIG_SMP |
154 | static int __init softlockup_all_cpu_backtrace_setup(char *str) | |
155 | { | |
156 | sysctl_softlockup_all_cpu_backtrace = | |
157 | !!simple_strtol(str, NULL, 0); | |
158 | return 1; | |
159 | } | |
160 | __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); | |
161 | #endif | |
58687acb | 162 | |
4eec42f3 MSB |
163 | /* |
164 | * Hard-lockup warnings should be triggered after just a few seconds. Soft- | |
165 | * lockups can have false positives under extreme conditions. So we generally | |
166 | * want a higher threshold for soft lockups than for hard lockups. So we couple | |
167 | * the thresholds with a factor: we make the soft threshold twice the amount of | |
168 | * time the hard threshold is. | |
169 | */ | |
6e9101ae | 170 | static int get_softlockup_thresh(void) |
4eec42f3 MSB |
171 | { |
172 | return watchdog_thresh * 2; | |
173 | } | |
58687acb DZ |
174 | |
175 | /* | |
176 | * Returns seconds, approximately. We don't need nanosecond | |
177 | * resolution, and we don't need to waste time with a big divide when | |
178 | * 2^30ns == 1.074s. | |
179 | */ | |
c06b4f19 | 180 | static unsigned long get_timestamp(void) |
58687acb | 181 | { |
545a2bf7 | 182 | return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ |
58687acb DZ |
183 | } |
184 | ||
0f34c400 | 185 | static void set_sample_period(void) |
58687acb DZ |
186 | { |
187 | /* | |
586692a5 | 188 | * convert watchdog_thresh from seconds to ns |
86f5e6a7 FLVC |
189 | * the divide by 5 is to give hrtimer several chances (two |
190 | * or three with the current relation between the soft | |
191 | * and hard thresholds) to increment before the | |
192 | * hardlockup detector generates a warning | |
58687acb | 193 | */ |
0f34c400 | 194 | sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); |
58687acb DZ |
195 | } |
196 | ||
197 | /* Commands for resetting the watchdog */ | |
198 | static void __touch_watchdog(void) | |
199 | { | |
c06b4f19 | 200 | __this_cpu_write(watchdog_touch_ts, get_timestamp()); |
58687acb DZ |
201 | } |
202 | ||
332fbdbc | 203 | void touch_softlockup_watchdog(void) |
58687acb | 204 | { |
7861144b AM |
205 | /* |
206 | * Preemption can be enabled. It doesn't matter which CPU's timestamp | |
207 | * gets zeroed here, so use the raw_ operation. | |
208 | */ | |
209 | raw_cpu_write(watchdog_touch_ts, 0); | |
58687acb | 210 | } |
0167c781 | 211 | EXPORT_SYMBOL(touch_softlockup_watchdog); |
58687acb | 212 | |
332fbdbc | 213 | void touch_all_softlockup_watchdogs(void) |
58687acb DZ |
214 | { |
215 | int cpu; | |
216 | ||
217 | /* | |
218 | * this is done lockless | |
219 | * do we care if a 0 races with a timestamp? | |
220 | * all it means is the softlock check starts one cycle later | |
221 | */ | |
222 | for_each_online_cpu(cpu) | |
223 | per_cpu(watchdog_touch_ts, cpu) = 0; | |
224 | } | |
225 | ||
cafcd80d | 226 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb DZ |
227 | void touch_nmi_watchdog(void) |
228 | { | |
62572e29 BZ |
229 | /* |
230 | * Using __raw here because some code paths have | |
231 | * preemption enabled. If preemption is enabled | |
232 | * then interrupts should be enabled too, in which | |
233 | * case we shouldn't have to worry about the watchdog | |
234 | * going off. | |
235 | */ | |
f7f66b05 | 236 | raw_cpu_write(watchdog_nmi_touch, true); |
332fbdbc | 237 | touch_softlockup_watchdog(); |
58687acb DZ |
238 | } |
239 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
240 | ||
cafcd80d DZ |
241 | #endif |
242 | ||
58687acb DZ |
243 | void touch_softlockup_watchdog_sync(void) |
244 | { | |
f7f66b05 CL |
245 | __this_cpu_write(softlockup_touch_sync, true); |
246 | __this_cpu_write(watchdog_touch_ts, 0); | |
58687acb DZ |
247 | } |
248 | ||
23637d47 | 249 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
58687acb | 250 | /* watchdog detector functions */ |
26e09c6e | 251 | static int is_hardlockup(void) |
58687acb | 252 | { |
909ea964 | 253 | unsigned long hrint = __this_cpu_read(hrtimer_interrupts); |
58687acb | 254 | |
909ea964 | 255 | if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) |
58687acb DZ |
256 | return 1; |
257 | ||
909ea964 | 258 | __this_cpu_write(hrtimer_interrupts_saved, hrint); |
58687acb DZ |
259 | return 0; |
260 | } | |
261 | #endif | |
262 | ||
26e09c6e | 263 | static int is_softlockup(unsigned long touch_ts) |
58687acb | 264 | { |
c06b4f19 | 265 | unsigned long now = get_timestamp(); |
58687acb DZ |
266 | |
267 | /* Warn about unreasonable delays: */ | |
4eec42f3 | 268 | if (time_after(now, touch_ts + get_softlockup_thresh())) |
58687acb DZ |
269 | return now - touch_ts; |
270 | ||
271 | return 0; | |
272 | } | |
273 | ||
23637d47 | 274 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
1880c4ae | 275 | |
58687acb DZ |
276 | static struct perf_event_attr wd_hw_attr = { |
277 | .type = PERF_TYPE_HARDWARE, | |
278 | .config = PERF_COUNT_HW_CPU_CYCLES, | |
279 | .size = sizeof(struct perf_event_attr), | |
280 | .pinned = 1, | |
281 | .disabled = 1, | |
282 | }; | |
283 | ||
284 | /* Callback function for perf event subsystem */ | |
a8b0ca17 | 285 | static void watchdog_overflow_callback(struct perf_event *event, |
58687acb DZ |
286 | struct perf_sample_data *data, |
287 | struct pt_regs *regs) | |
288 | { | |
c6db67cd PZ |
289 | /* Ensure the watchdog never gets throttled */ |
290 | event->hw.interrupts = 0; | |
291 | ||
909ea964 CL |
292 | if (__this_cpu_read(watchdog_nmi_touch) == true) { |
293 | __this_cpu_write(watchdog_nmi_touch, false); | |
58687acb DZ |
294 | return; |
295 | } | |
296 | ||
297 | /* check for a hardlockup | |
298 | * This is done by making sure our timer interrupt | |
299 | * is incrementing. The timer interrupt should have | |
300 | * fired multiple times before we overflow'd. If it hasn't | |
301 | * then this is a good indication the cpu is stuck | |
302 | */ | |
26e09c6e DZ |
303 | if (is_hardlockup()) { |
304 | int this_cpu = smp_processor_id(); | |
305 | ||
58687acb | 306 | /* only print hardlockups once */ |
909ea964 | 307 | if (__this_cpu_read(hard_watchdog_warn) == true) |
58687acb DZ |
308 | return; |
309 | ||
310 | if (hardlockup_panic) | |
656c3b79 FF |
311 | panic("Watchdog detected hard LOCKUP on cpu %d", |
312 | this_cpu); | |
58687acb | 313 | else |
656c3b79 FF |
314 | WARN(1, "Watchdog detected hard LOCKUP on cpu %d", |
315 | this_cpu); | |
58687acb | 316 | |
909ea964 | 317 | __this_cpu_write(hard_watchdog_warn, true); |
58687acb DZ |
318 | return; |
319 | } | |
320 | ||
909ea964 | 321 | __this_cpu_write(hard_watchdog_warn, false); |
58687acb DZ |
322 | return; |
323 | } | |
bcd951cf TG |
324 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
325 | ||
58687acb DZ |
326 | static void watchdog_interrupt_count(void) |
327 | { | |
909ea964 | 328 | __this_cpu_inc(hrtimer_interrupts); |
58687acb | 329 | } |
bcd951cf TG |
330 | |
331 | static int watchdog_nmi_enable(unsigned int cpu); | |
332 | static void watchdog_nmi_disable(unsigned int cpu); | |
58687acb DZ |
333 | |
334 | /* watchdog kicker functions */ | |
335 | static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) | |
336 | { | |
909ea964 | 337 | unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); |
58687acb DZ |
338 | struct pt_regs *regs = get_irq_regs(); |
339 | int duration; | |
ed235875 | 340 | int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; |
58687acb DZ |
341 | |
342 | /* kick the hardlockup detector */ | |
343 | watchdog_interrupt_count(); | |
344 | ||
345 | /* kick the softlockup detector */ | |
909ea964 | 346 | wake_up_process(__this_cpu_read(softlockup_watchdog)); |
58687acb DZ |
347 | |
348 | /* .. and repeat */ | |
0f34c400 | 349 | hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
58687acb DZ |
350 | |
351 | if (touch_ts == 0) { | |
909ea964 | 352 | if (unlikely(__this_cpu_read(softlockup_touch_sync))) { |
58687acb DZ |
353 | /* |
354 | * If the time stamp was touched atomically | |
355 | * make sure the scheduler tick is up to date. | |
356 | */ | |
909ea964 | 357 | __this_cpu_write(softlockup_touch_sync, false); |
58687acb DZ |
358 | sched_clock_tick(); |
359 | } | |
5d1c0f4a EM |
360 | |
361 | /* Clear the guest paused flag on watchdog reset */ | |
362 | kvm_check_and_clear_guest_paused(); | |
58687acb DZ |
363 | __touch_watchdog(); |
364 | return HRTIMER_RESTART; | |
365 | } | |
366 | ||
367 | /* check for a softlockup | |
368 | * This is done by making sure a high priority task is | |
369 | * being scheduled. The task touches the watchdog to | |
370 | * indicate it is getting cpu time. If it hasn't then | |
371 | * this is a good indication some task is hogging the cpu | |
372 | */ | |
26e09c6e | 373 | duration = is_softlockup(touch_ts); |
58687acb | 374 | if (unlikely(duration)) { |
5d1c0f4a EM |
375 | /* |
376 | * If a virtual machine is stopped by the host it can look to | |
377 | * the watchdog like a soft lockup, check to see if the host | |
378 | * stopped the vm before we issue the warning | |
379 | */ | |
380 | if (kvm_check_and_clear_guest_paused()) | |
381 | return HRTIMER_RESTART; | |
382 | ||
58687acb | 383 | /* only warn once */ |
b1a8de1f | 384 | if (__this_cpu_read(soft_watchdog_warn) == true) { |
385 | /* | |
386 | * When multiple processes are causing softlockups the | |
387 | * softlockup detector only warns on the first one | |
388 | * because the code relies on a full quiet cycle to | |
389 | * re-arm. The second process prevents the quiet cycle | |
390 | * and never gets reported. Use task pointers to detect | |
391 | * this. | |
392 | */ | |
393 | if (__this_cpu_read(softlockup_task_ptr_saved) != | |
394 | current) { | |
395 | __this_cpu_write(soft_watchdog_warn, false); | |
396 | __touch_watchdog(); | |
397 | } | |
58687acb | 398 | return HRTIMER_RESTART; |
b1a8de1f | 399 | } |
58687acb | 400 | |
ed235875 AT |
401 | if (softlockup_all_cpu_backtrace) { |
402 | /* Prevent multiple soft-lockup reports if one cpu is already | |
403 | * engaged in dumping cpu back traces | |
404 | */ | |
405 | if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { | |
406 | /* Someone else will report us. Let's give up */ | |
407 | __this_cpu_write(soft_watchdog_warn, true); | |
408 | return HRTIMER_RESTART; | |
409 | } | |
410 | } | |
411 | ||
656c3b79 | 412 | pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", |
26e09c6e | 413 | smp_processor_id(), duration, |
58687acb | 414 | current->comm, task_pid_nr(current)); |
b1a8de1f | 415 | __this_cpu_write(softlockup_task_ptr_saved, current); |
58687acb DZ |
416 | print_modules(); |
417 | print_irqtrace_events(current); | |
418 | if (regs) | |
419 | show_regs(regs); | |
420 | else | |
421 | dump_stack(); | |
422 | ||
ed235875 AT |
423 | if (softlockup_all_cpu_backtrace) { |
424 | /* Avoid generating two back traces for current | |
425 | * given that one is already made above | |
426 | */ | |
427 | trigger_allbutself_cpu_backtrace(); | |
428 | ||
429 | clear_bit(0, &soft_lockup_nmi_warn); | |
430 | /* Barrier to sync with other cpus */ | |
431 | smp_mb__after_atomic(); | |
432 | } | |
433 | ||
69361eef | 434 | add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); |
58687acb DZ |
435 | if (softlockup_panic) |
436 | panic("softlockup: hung tasks"); | |
909ea964 | 437 | __this_cpu_write(soft_watchdog_warn, true); |
58687acb | 438 | } else |
909ea964 | 439 | __this_cpu_write(soft_watchdog_warn, false); |
58687acb DZ |
440 | |
441 | return HRTIMER_RESTART; | |
442 | } | |
443 | ||
bcd951cf TG |
444 | static void watchdog_set_prio(unsigned int policy, unsigned int prio) |
445 | { | |
446 | struct sched_param param = { .sched_priority = prio }; | |
58687acb | 447 | |
bcd951cf TG |
448 | sched_setscheduler(current, policy, ¶m); |
449 | } | |
450 | ||
451 | static void watchdog_enable(unsigned int cpu) | |
58687acb | 452 | { |
f7f66b05 | 453 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acb | 454 | |
3935e895 BM |
455 | /* kick off the timer for the hardlockup detector */ |
456 | hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
457 | hrtimer->function = watchdog_timer_fn; | |
458 | ||
bcd951cf TG |
459 | /* Enable the perf event */ |
460 | watchdog_nmi_enable(cpu); | |
58687acb | 461 | |
58687acb | 462 | /* done here because hrtimer_start can only pin to smp_processor_id() */ |
0f34c400 | 463 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
58687acb DZ |
464 | HRTIMER_MODE_REL_PINNED); |
465 | ||
bcd951cf TG |
466 | /* initialize timestamp */ |
467 | watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); | |
468 | __touch_watchdog(); | |
469 | } | |
58687acb | 470 | |
bcd951cf TG |
471 | static void watchdog_disable(unsigned int cpu) |
472 | { | |
f7f66b05 | 473 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
58687acb | 474 | |
bcd951cf TG |
475 | watchdog_set_prio(SCHED_NORMAL, 0); |
476 | hrtimer_cancel(hrtimer); | |
477 | /* disable the perf event */ | |
478 | watchdog_nmi_disable(cpu); | |
58687acb DZ |
479 | } |
480 | ||
b8900bc0 FW |
481 | static void watchdog_cleanup(unsigned int cpu, bool online) |
482 | { | |
483 | watchdog_disable(cpu); | |
484 | } | |
485 | ||
bcd951cf TG |
486 | static int watchdog_should_run(unsigned int cpu) |
487 | { | |
488 | return __this_cpu_read(hrtimer_interrupts) != | |
489 | __this_cpu_read(soft_lockup_hrtimer_cnt); | |
490 | } | |
491 | ||
492 | /* | |
493 | * The watchdog thread function - touches the timestamp. | |
494 | * | |
0f34c400 | 495 | * It only runs once every sample_period seconds (4 seconds by |
bcd951cf TG |
496 | * default) to reset the softlockup timestamp. If this gets delayed |
497 | * for more than 2*watchdog_thresh seconds then the debug-printout | |
498 | * triggers in watchdog_timer_fn(). | |
499 | */ | |
500 | static void watchdog(unsigned int cpu) | |
501 | { | |
502 | __this_cpu_write(soft_lockup_hrtimer_cnt, | |
503 | __this_cpu_read(hrtimer_interrupts)); | |
504 | __touch_watchdog(); | |
bcfba4f4 UO |
505 | |
506 | /* | |
507 | * watchdog_nmi_enable() clears the NMI_WATCHDOG_ENABLED bit in the | |
508 | * failure path. Check for failures that can occur asynchronously - | |
509 | * for example, when CPUs are on-lined - and shut down the hardware | |
510 | * perf event on each CPU accordingly. | |
511 | * | |
512 | * The only non-obvious place this bit can be cleared is through | |
513 | * watchdog_nmi_enable(), so a pr_info() is placed there. Placing a | |
514 | * pr_info here would be too noisy as it would result in a message | |
515 | * every few seconds if the hardlockup was disabled but the softlockup | |
516 | * enabled. | |
517 | */ | |
518 | if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED)) | |
519 | watchdog_nmi_disable(cpu); | |
bcd951cf | 520 | } |
58687acb | 521 | |
23637d47 | 522 | #ifdef CONFIG_HARDLOCKUP_DETECTOR |
a7027046 DZ |
523 | /* |
524 | * People like the simple clean cpu node info on boot. | |
525 | * Reduce the watchdog noise by only printing messages | |
526 | * that are different from what cpu0 displayed. | |
527 | */ | |
528 | static unsigned long cpu0_err; | |
529 | ||
bcd951cf | 530 | static int watchdog_nmi_enable(unsigned int cpu) |
58687acb DZ |
531 | { |
532 | struct perf_event_attr *wd_attr; | |
533 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
534 | ||
6e7458a6 UO |
535 | /* |
536 | * Some kernels need to default hard lockup detection to | |
537 | * 'disabled', for example a guest on a hypervisor. | |
538 | */ | |
539 | if (!watchdog_hardlockup_detector_is_enabled()) { | |
540 | event = ERR_PTR(-ENOENT); | |
541 | goto handle_err; | |
542 | } | |
543 | ||
58687acb DZ |
544 | /* is it already setup and enabled? */ |
545 | if (event && event->state > PERF_EVENT_STATE_OFF) | |
546 | goto out; | |
547 | ||
548 | /* it is setup but not enabled */ | |
549 | if (event != NULL) | |
550 | goto out_enable; | |
551 | ||
58687acb | 552 | wd_attr = &wd_hw_attr; |
4eec42f3 | 553 | wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); |
1880c4ae CG |
554 | |
555 | /* Try to register using hardware perf events */ | |
4dc0da86 | 556 | event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL); |
a7027046 | 557 | |
6e7458a6 | 558 | handle_err: |
a7027046 DZ |
559 | /* save cpu0 error for future comparision */ |
560 | if (cpu == 0 && IS_ERR(event)) | |
561 | cpu0_err = PTR_ERR(event); | |
562 | ||
58687acb | 563 | if (!IS_ERR(event)) { |
a7027046 DZ |
564 | /* only print for cpu0 or different than cpu0 */ |
565 | if (cpu == 0 || cpu0_err) | |
566 | pr_info("enabled on all CPUs, permanently consumes one hw-PMU counter.\n"); | |
58687acb DZ |
567 | goto out_save; |
568 | } | |
569 | ||
bcfba4f4 UO |
570 | /* |
571 | * Disable the hard lockup detector if _any_ CPU fails to set up | |
572 | * set up the hardware perf event. The watchdog() function checks | |
573 | * the NMI_WATCHDOG_ENABLED bit periodically. | |
574 | * | |
575 | * The barriers are for syncing up watchdog_enabled across all the | |
576 | * cpus, as clear_bit() does not use barriers. | |
577 | */ | |
578 | smp_mb__before_atomic(); | |
579 | clear_bit(NMI_WATCHDOG_ENABLED_BIT, &watchdog_enabled); | |
580 | smp_mb__after_atomic(); | |
581 | ||
a7027046 DZ |
582 | /* skip displaying the same error again */ |
583 | if (cpu > 0 && (PTR_ERR(event) == cpu0_err)) | |
584 | return PTR_ERR(event); | |
5651f7f4 DZ |
585 | |
586 | /* vary the KERN level based on the returned errno */ | |
587 | if (PTR_ERR(event) == -EOPNOTSUPP) | |
4501980a | 588 | pr_info("disabled (cpu%i): not supported (no LAPIC?)\n", cpu); |
5651f7f4 | 589 | else if (PTR_ERR(event) == -ENOENT) |
656c3b79 | 590 | pr_warn("disabled (cpu%i): hardware events not enabled\n", |
4501980a | 591 | cpu); |
5651f7f4 | 592 | else |
4501980a AM |
593 | pr_err("disabled (cpu%i): unable to create perf event: %ld\n", |
594 | cpu, PTR_ERR(event)); | |
bcfba4f4 UO |
595 | |
596 | pr_info("Shutting down hard lockup detector on all cpus\n"); | |
597 | ||
eac24335 | 598 | return PTR_ERR(event); |
58687acb DZ |
599 | |
600 | /* success path */ | |
601 | out_save: | |
602 | per_cpu(watchdog_ev, cpu) = event; | |
603 | out_enable: | |
604 | perf_event_enable(per_cpu(watchdog_ev, cpu)); | |
605 | out: | |
606 | return 0; | |
607 | } | |
608 | ||
bcd951cf | 609 | static void watchdog_nmi_disable(unsigned int cpu) |
58687acb DZ |
610 | { |
611 | struct perf_event *event = per_cpu(watchdog_ev, cpu); | |
612 | ||
613 | if (event) { | |
614 | perf_event_disable(event); | |
615 | per_cpu(watchdog_ev, cpu) = NULL; | |
616 | ||
617 | /* should be in cleanup, but blocks oprofile */ | |
618 | perf_event_release_kernel(event); | |
619 | } | |
df577149 UO |
620 | if (cpu == 0) { |
621 | /* watchdog_nmi_enable() expects this to be zero initially. */ | |
622 | cpu0_err = 0; | |
623 | } | |
58687acb DZ |
624 | } |
625 | #else | |
bcd951cf TG |
626 | static int watchdog_nmi_enable(unsigned int cpu) { return 0; } |
627 | static void watchdog_nmi_disable(unsigned int cpu) { return; } | |
23637d47 | 628 | #endif /* CONFIG_HARDLOCKUP_DETECTOR */ |
58687acb | 629 | |
b8900bc0 FW |
630 | static struct smp_hotplug_thread watchdog_threads = { |
631 | .store = &softlockup_watchdog, | |
632 | .thread_should_run = watchdog_should_run, | |
633 | .thread_fn = watchdog, | |
634 | .thread_comm = "watchdog/%u", | |
635 | .setup = watchdog_enable, | |
636 | .cleanup = watchdog_cleanup, | |
637 | .park = watchdog_disable, | |
638 | .unpark = watchdog_enable, | |
639 | }; | |
640 | ||
9809b18f MH |
641 | static void restart_watchdog_hrtimer(void *info) |
642 | { | |
f7f66b05 | 643 | struct hrtimer *hrtimer = raw_cpu_ptr(&watchdog_hrtimer); |
9809b18f MH |
644 | int ret; |
645 | ||
646 | /* | |
647 | * No need to cancel and restart hrtimer if it is currently executing | |
648 | * because it will reprogram itself with the new period now. | |
649 | * We should never see it unqueued here because we are running per-cpu | |
650 | * with interrupts disabled. | |
651 | */ | |
652 | ret = hrtimer_try_to_cancel(hrtimer); | |
653 | if (ret == 1) | |
654 | hrtimer_start(hrtimer, ns_to_ktime(sample_period), | |
655 | HRTIMER_MODE_REL_PINNED); | |
656 | } | |
657 | ||
658 | static void update_timers(int cpu) | |
659 | { | |
9809b18f MH |
660 | /* |
661 | * Make sure that perf event counter will adopt to a new | |
662 | * sampling period. Updating the sampling period directly would | |
663 | * be much nicer but we do not have an API for that now so | |
664 | * let's use a big hammer. | |
665 | * Hrtimer will adopt the new period on the next tick but this | |
666 | * might be late already so we have to restart the timer as well. | |
667 | */ | |
668 | watchdog_nmi_disable(cpu); | |
e0a23b06 | 669 | smp_call_function_single(cpu, restart_watchdog_hrtimer, NULL, 1); |
9809b18f MH |
670 | watchdog_nmi_enable(cpu); |
671 | } | |
672 | ||
673 | static void update_timers_all_cpus(void) | |
674 | { | |
675 | int cpu; | |
676 | ||
677 | get_online_cpus(); | |
9809b18f MH |
678 | for_each_online_cpu(cpu) |
679 | update_timers(cpu); | |
9809b18f MH |
680 | put_online_cpus(); |
681 | } | |
682 | ||
683 | static int watchdog_enable_all_cpus(bool sample_period_changed) | |
58687acb | 684 | { |
b8900bc0 | 685 | int err = 0; |
58687acb | 686 | |
3c00ea82 | 687 | if (!watchdog_running) { |
b8900bc0 FW |
688 | err = smpboot_register_percpu_thread(&watchdog_threads); |
689 | if (err) | |
690 | pr_err("Failed to create watchdog threads, disabled\n"); | |
691 | else | |
3c00ea82 | 692 | watchdog_running = 1; |
9809b18f MH |
693 | } else if (sample_period_changed) { |
694 | update_timers_all_cpus(); | |
bcd951cf | 695 | } |
b8900bc0 FW |
696 | |
697 | return err; | |
58687acb DZ |
698 | } |
699 | ||
b8900bc0 FW |
700 | /* prepare/enable/disable routines */ |
701 | /* sysctl functions */ | |
702 | #ifdef CONFIG_SYSCTL | |
58687acb DZ |
703 | static void watchdog_disable_all_cpus(void) |
704 | { | |
3c00ea82 FW |
705 | if (watchdog_running) { |
706 | watchdog_running = 0; | |
b8900bc0 | 707 | smpboot_unregister_percpu_thread(&watchdog_threads); |
bcd951cf | 708 | } |
58687acb DZ |
709 | } |
710 | ||
a0c9cbb9 UO |
711 | /* |
712 | * Update the run state of the lockup detectors. | |
713 | */ | |
714 | static int proc_watchdog_update(void) | |
715 | { | |
716 | int err = 0; | |
717 | ||
718 | /* | |
719 | * Watchdog threads won't be started if they are already active. | |
720 | * The 'watchdog_running' variable in watchdog_*_all_cpus() takes | |
721 | * care of this. If those threads are already active, the sample | |
722 | * period will be updated and the lockup detectors will be enabled | |
723 | * or disabled 'on the fly'. | |
724 | */ | |
725 | if (watchdog_enabled && watchdog_thresh) | |
726 | err = watchdog_enable_all_cpus(true); | |
727 | else | |
728 | watchdog_disable_all_cpus(); | |
729 | ||
730 | return err; | |
731 | ||
732 | } | |
733 | ||
f54c2274 UO |
734 | static DEFINE_MUTEX(watchdog_proc_mutex); |
735 | ||
ef246a21 UO |
736 | /* |
737 | * common function for watchdog, nmi_watchdog and soft_watchdog parameter | |
738 | * | |
739 | * caller | table->data points to | 'which' contains the flag(s) | |
740 | * -------------------|-----------------------|----------------------------- | |
741 | * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED or'ed | |
742 | * | | with SOFT_WATCHDOG_ENABLED | |
743 | * -------------------|-----------------------|----------------------------- | |
744 | * proc_nmi_watchdog | nmi_watchdog_enabled | NMI_WATCHDOG_ENABLED | |
745 | * -------------------|-----------------------|----------------------------- | |
746 | * proc_soft_watchdog | soft_watchdog_enabled | SOFT_WATCHDOG_ENABLED | |
747 | */ | |
748 | static int proc_watchdog_common(int which, struct ctl_table *table, int write, | |
749 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
750 | { | |
751 | int err, old, new; | |
752 | int *watchdog_param = (int *)table->data; | |
753 | ||
754 | mutex_lock(&watchdog_proc_mutex); | |
755 | ||
756 | /* | |
757 | * If the parameter is being read return the state of the corresponding | |
758 | * bit(s) in 'watchdog_enabled', else update 'watchdog_enabled' and the | |
759 | * run state of the lockup detectors. | |
760 | */ | |
761 | if (!write) { | |
762 | *watchdog_param = (watchdog_enabled & which) != 0; | |
763 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
764 | } else { | |
765 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
766 | if (err) | |
767 | goto out; | |
768 | ||
769 | /* | |
770 | * There is a race window between fetching the current value | |
771 | * from 'watchdog_enabled' and storing the new value. During | |
772 | * this race window, watchdog_nmi_enable() can sneak in and | |
773 | * clear the NMI_WATCHDOG_ENABLED bit in 'watchdog_enabled'. | |
774 | * The 'cmpxchg' detects this race and the loop retries. | |
775 | */ | |
776 | do { | |
777 | old = watchdog_enabled; | |
778 | /* | |
779 | * If the parameter value is not zero set the | |
780 | * corresponding bit(s), else clear it(them). | |
781 | */ | |
782 | if (*watchdog_param) | |
783 | new = old | which; | |
784 | else | |
785 | new = old & ~which; | |
786 | } while (cmpxchg(&watchdog_enabled, old, new) != old); | |
787 | ||
788 | /* | |
789 | * Update the run state of the lockup detectors. | |
790 | * Restore 'watchdog_enabled' on failure. | |
791 | */ | |
792 | err = proc_watchdog_update(); | |
793 | if (err) | |
794 | watchdog_enabled = old; | |
795 | } | |
796 | out: | |
797 | mutex_unlock(&watchdog_proc_mutex); | |
798 | return err; | |
799 | } | |
800 | ||
83a80a39 UO |
801 | /* |
802 | * /proc/sys/kernel/watchdog | |
803 | */ | |
804 | int proc_watchdog(struct ctl_table *table, int write, | |
805 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
806 | { | |
807 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, | |
808 | table, write, buffer, lenp, ppos); | |
809 | } | |
810 | ||
811 | /* | |
812 | * /proc/sys/kernel/nmi_watchdog | |
813 | */ | |
814 | int proc_nmi_watchdog(struct ctl_table *table, int write, | |
815 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
816 | { | |
817 | return proc_watchdog_common(NMI_WATCHDOG_ENABLED, | |
818 | table, write, buffer, lenp, ppos); | |
819 | } | |
820 | ||
821 | /* | |
822 | * /proc/sys/kernel/soft_watchdog | |
823 | */ | |
824 | int proc_soft_watchdog(struct ctl_table *table, int write, | |
825 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
826 | { | |
827 | return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, | |
828 | table, write, buffer, lenp, ppos); | |
829 | } | |
830 | ||
831 | /* | |
832 | * /proc/sys/kernel/watchdog_thresh | |
833 | */ | |
834 | int proc_watchdog_thresh(struct ctl_table *table, int write, | |
835 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
836 | { | |
837 | int err, old; | |
838 | ||
839 | mutex_lock(&watchdog_proc_mutex); | |
840 | ||
841 | old = ACCESS_ONCE(watchdog_thresh); | |
842 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
843 | ||
844 | if (err || !write) | |
845 | goto out; | |
846 | ||
847 | /* | |
848 | * Update the sample period. | |
849 | * Restore 'watchdog_thresh' on failure. | |
850 | */ | |
851 | set_sample_period(); | |
852 | err = proc_watchdog_update(); | |
853 | if (err) | |
854 | watchdog_thresh = old; | |
855 | out: | |
856 | mutex_unlock(&watchdog_proc_mutex); | |
857 | return err; | |
858 | } | |
859 | ||
58687acb | 860 | /* |
586692a5 | 861 | * proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh |
58687acb DZ |
862 | */ |
863 | ||
586692a5 MSB |
864 | int proc_dowatchdog(struct ctl_table *table, int write, |
865 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
58687acb | 866 | { |
b8900bc0 | 867 | int err, old_thresh, old_enabled; |
6e7458a6 | 868 | bool old_hardlockup; |
58687acb | 869 | |
359e6fab | 870 | mutex_lock(&watchdog_proc_mutex); |
b8900bc0 | 871 | old_thresh = ACCESS_ONCE(watchdog_thresh); |
3c00ea82 | 872 | old_enabled = ACCESS_ONCE(watchdog_user_enabled); |
6e7458a6 | 873 | old_hardlockup = watchdog_hardlockup_detector_is_enabled(); |
bcd951cf | 874 | |
b8900bc0 FW |
875 | err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
876 | if (err || !write) | |
359e6fab | 877 | goto out; |
e04ab2bc | 878 | |
0f34c400 | 879 | set_sample_period(); |
b66a2356 | 880 | /* |
881 | * Watchdog threads shouldn't be enabled if they are | |
3c00ea82 | 882 | * disabled. The 'watchdog_running' variable check in |
b66a2356 | 883 | * watchdog_*_all_cpus() function takes care of this. |
884 | */ | |
6e7458a6 UO |
885 | if (watchdog_user_enabled && watchdog_thresh) { |
886 | /* | |
887 | * Prevent a change in watchdog_thresh accidentally overriding | |
888 | * the enablement of the hardlockup detector. | |
889 | */ | |
890 | if (watchdog_user_enabled != old_enabled) | |
891 | watchdog_enable_hardlockup_detector(true); | |
9809b18f | 892 | err = watchdog_enable_all_cpus(old_thresh != watchdog_thresh); |
6e7458a6 | 893 | } else |
e04ab2bc MSB |
894 | watchdog_disable_all_cpus(); |
895 | ||
b8900bc0 FW |
896 | /* Restore old values on failure */ |
897 | if (err) { | |
898 | watchdog_thresh = old_thresh; | |
3c00ea82 | 899 | watchdog_user_enabled = old_enabled; |
6e7458a6 | 900 | watchdog_enable_hardlockup_detector(old_hardlockup); |
b8900bc0 | 901 | } |
359e6fab MH |
902 | out: |
903 | mutex_unlock(&watchdog_proc_mutex); | |
b8900bc0 | 904 | return err; |
58687acb | 905 | } |
58687acb DZ |
906 | #endif /* CONFIG_SYSCTL */ |
907 | ||
004417a6 | 908 | void __init lockup_detector_init(void) |
58687acb | 909 | { |
0f34c400 | 910 | set_sample_period(); |
b8900bc0 | 911 | |
3c00ea82 | 912 | if (watchdog_user_enabled) |
9809b18f | 913 | watchdog_enable_all_cpus(false); |
58687acb | 914 | } |