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1 | /* | |
2 | * NMI watchdog support on APIC systems | |
3 | * | |
4 | * Started by Ingo Molnar <mingo@redhat.com> | |
5 | * | |
6 | * Fixes: | |
7 | * Mikael Pettersson : AMD K7 support for local APIC NMI watchdog. | |
8 | * Mikael Pettersson : Power Management for local APIC NMI watchdog. | |
9 | * Pavel Machek and | |
10 | * Mikael Pettersson : PM converted to driver model. Disable/enable API. | |
11 | */ | |
12 | ||
13 | #include <linux/nmi.h> | |
14 | #include <linux/mm.h> | |
15 | #include <linux/delay.h> | |
16 | #include <linux/interrupt.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/sysdev.h> | |
19 | #include <linux/sysctl.h> | |
20 | #include <linux/kprobes.h> | |
21 | #include <linux/cpumask.h> | |
22 | #include <linux/kdebug.h> | |
23 | ||
24 | #include <asm/smp.h> | |
25 | #include <asm/nmi.h> | |
26 | #include <asm/proto.h> | |
27 | #include <asm/mce.h> | |
28 | ||
29 | #include <mach_traps.h> | |
30 | ||
31 | int unknown_nmi_panic; | |
32 | int nmi_watchdog_enabled; | |
33 | int panic_on_unrecovered_nmi; | |
34 | ||
35 | static cpumask_t backtrace_mask = CPU_MASK_NONE; | |
36 | ||
37 | /* nmi_active: | |
38 | * >0: the lapic NMI watchdog is active, but can be disabled | |
39 | * <0: the lapic NMI watchdog has not been set up, and cannot | |
40 | * be enabled | |
41 | * 0: the lapic NMI watchdog is disabled, but can be enabled | |
42 | */ | |
43 | atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */ | |
44 | static int panic_on_timeout; | |
45 | ||
46 | unsigned int nmi_watchdog = NMI_DEFAULT; | |
47 | static unsigned int nmi_hz = HZ; | |
48 | ||
49 | static DEFINE_PER_CPU(short, wd_enabled); | |
50 | ||
51 | /* Run after command line and cpu_init init, but before all other checks */ | |
52 | void nmi_watchdog_default(void) | |
53 | { | |
54 | if (nmi_watchdog != NMI_DEFAULT) | |
55 | return; | |
56 | nmi_watchdog = NMI_NONE; | |
57 | } | |
58 | ||
59 | static int endflag __initdata = 0; | |
60 | ||
61 | #ifdef CONFIG_SMP | |
62 | /* The performance counters used by NMI_LOCAL_APIC don't trigger when | |
63 | * the CPU is idle. To make sure the NMI watchdog really ticks on all | |
64 | * CPUs during the test make them busy. | |
65 | */ | |
66 | static __init void nmi_cpu_busy(void *data) | |
67 | { | |
68 | local_irq_enable_in_hardirq(); | |
69 | /* Intentionally don't use cpu_relax here. This is | |
70 | to make sure that the performance counter really ticks, | |
71 | even if there is a simulator or similar that catches the | |
72 | pause instruction. On a real HT machine this is fine because | |
73 | all other CPUs are busy with "useless" delay loops and don't | |
74 | care if they get somewhat less cycles. */ | |
75 | while (endflag == 0) | |
76 | mb(); | |
77 | } | |
78 | #endif | |
79 | ||
80 | int __init check_nmi_watchdog(void) | |
81 | { | |
82 | int *prev_nmi_count; | |
83 | int cpu; | |
84 | ||
85 | if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED)) | |
86 | return 0; | |
87 | ||
88 | if (!atomic_read(&nmi_active)) | |
89 | return 0; | |
90 | ||
91 | prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL); | |
92 | if (!prev_nmi_count) | |
93 | return -1; | |
94 | ||
95 | printk(KERN_INFO "Testing NMI watchdog ... "); | |
96 | ||
97 | #ifdef CONFIG_SMP | |
98 | if (nmi_watchdog == NMI_LOCAL_APIC) | |
99 | smp_call_function(nmi_cpu_busy, (void *)&endflag, 0); | |
100 | #endif | |
101 | ||
102 | for (cpu = 0; cpu < NR_CPUS; cpu++) | |
103 | prev_nmi_count[cpu] = cpu_pda(cpu)->__nmi_count; | |
104 | local_irq_enable(); | |
105 | mdelay((20*1000)/nmi_hz); // wait 20 ticks | |
106 | ||
107 | for_each_online_cpu(cpu) { | |
108 | if (!per_cpu(wd_enabled, cpu)) | |
109 | continue; | |
110 | if (cpu_pda(cpu)->__nmi_count - prev_nmi_count[cpu] <= 5) { | |
111 | printk(KERN_WARNING "WARNING: CPU#%d: NMI " | |
112 | "appears to be stuck (%d->%d)!\n", | |
113 | cpu, | |
114 | prev_nmi_count[cpu], | |
115 | cpu_pda(cpu)->__nmi_count); | |
116 | per_cpu(wd_enabled, cpu) = 0; | |
117 | atomic_dec(&nmi_active); | |
118 | } | |
119 | } | |
120 | endflag = 1; | |
121 | if (!atomic_read(&nmi_active)) { | |
122 | kfree(prev_nmi_count); | |
123 | atomic_set(&nmi_active, -1); | |
124 | return -1; | |
125 | } | |
126 | printk("OK.\n"); | |
127 | ||
128 | /* now that we know it works we can reduce NMI frequency to | |
129 | something more reasonable; makes a difference in some configs */ | |
130 | if (nmi_watchdog == NMI_LOCAL_APIC) | |
131 | nmi_hz = lapic_adjust_nmi_hz(1); | |
132 | ||
133 | kfree(prev_nmi_count); | |
134 | return 0; | |
135 | } | |
136 | ||
137 | static int __init setup_nmi_watchdog(char *str) | |
138 | { | |
139 | int nmi; | |
140 | ||
141 | if (!strncmp(str,"panic",5)) { | |
142 | panic_on_timeout = 1; | |
143 | str = strchr(str, ','); | |
144 | if (!str) | |
145 | return 1; | |
146 | ++str; | |
147 | } | |
148 | ||
149 | get_option(&str, &nmi); | |
150 | ||
151 | if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE)) | |
152 | return 0; | |
153 | ||
154 | nmi_watchdog = nmi; | |
155 | return 1; | |
156 | } | |
157 | ||
158 | __setup("nmi_watchdog=", setup_nmi_watchdog); | |
159 | ||
160 | #ifdef CONFIG_PM | |
161 | ||
162 | static int nmi_pm_active; /* nmi_active before suspend */ | |
163 | ||
164 | static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state) | |
165 | { | |
166 | /* only CPU0 goes here, other CPUs should be offline */ | |
167 | nmi_pm_active = atomic_read(&nmi_active); | |
168 | stop_apic_nmi_watchdog(NULL); | |
169 | BUG_ON(atomic_read(&nmi_active) != 0); | |
170 | return 0; | |
171 | } | |
172 | ||
173 | static int lapic_nmi_resume(struct sys_device *dev) | |
174 | { | |
175 | /* only CPU0 goes here, other CPUs should be offline */ | |
176 | if (nmi_pm_active > 0) { | |
177 | setup_apic_nmi_watchdog(NULL); | |
178 | touch_nmi_watchdog(); | |
179 | } | |
180 | return 0; | |
181 | } | |
182 | ||
183 | static struct sysdev_class nmi_sysclass = { | |
184 | .name = "lapic_nmi", | |
185 | .resume = lapic_nmi_resume, | |
186 | .suspend = lapic_nmi_suspend, | |
187 | }; | |
188 | ||
189 | static struct sys_device device_lapic_nmi = { | |
190 | .id = 0, | |
191 | .cls = &nmi_sysclass, | |
192 | }; | |
193 | ||
194 | static int __init init_lapic_nmi_sysfs(void) | |
195 | { | |
196 | int error; | |
197 | ||
198 | /* should really be a BUG_ON but b/c this is an | |
199 | * init call, it just doesn't work. -dcz | |
200 | */ | |
201 | if (nmi_watchdog != NMI_LOCAL_APIC) | |
202 | return 0; | |
203 | ||
204 | if (atomic_read(&nmi_active) < 0) | |
205 | return 0; | |
206 | ||
207 | error = sysdev_class_register(&nmi_sysclass); | |
208 | if (!error) | |
209 | error = sysdev_register(&device_lapic_nmi); | |
210 | return error; | |
211 | } | |
212 | /* must come after the local APIC's device_initcall() */ | |
213 | late_initcall(init_lapic_nmi_sysfs); | |
214 | ||
215 | #endif /* CONFIG_PM */ | |
216 | ||
217 | static void __acpi_nmi_enable(void *__unused) | |
218 | { | |
219 | apic_write(APIC_LVT0, APIC_DM_NMI); | |
220 | } | |
221 | ||
222 | /* | |
223 | * Enable timer based NMIs on all CPUs: | |
224 | */ | |
225 | void acpi_nmi_enable(void) | |
226 | { | |
227 | if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC) | |
228 | on_each_cpu(__acpi_nmi_enable, NULL, 0, 1); | |
229 | } | |
230 | ||
231 | static void __acpi_nmi_disable(void *__unused) | |
232 | { | |
233 | apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED); | |
234 | } | |
235 | ||
236 | /* | |
237 | * Disable timer based NMIs on all CPUs: | |
238 | */ | |
239 | void acpi_nmi_disable(void) | |
240 | { | |
241 | if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC) | |
242 | on_each_cpu(__acpi_nmi_disable, NULL, 0, 1); | |
243 | } | |
244 | ||
245 | void setup_apic_nmi_watchdog(void *unused) | |
246 | { | |
247 | if (__get_cpu_var(wd_enabled)) | |
248 | return; | |
249 | ||
250 | /* cheap hack to support suspend/resume */ | |
251 | /* if cpu0 is not active neither should the other cpus */ | |
252 | if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0)) | |
253 | return; | |
254 | ||
255 | switch (nmi_watchdog) { | |
256 | case NMI_LOCAL_APIC: | |
257 | __get_cpu_var(wd_enabled) = 1; | |
258 | if (lapic_watchdog_init(nmi_hz) < 0) { | |
259 | __get_cpu_var(wd_enabled) = 0; | |
260 | return; | |
261 | } | |
262 | /* FALL THROUGH */ | |
263 | case NMI_IO_APIC: | |
264 | __get_cpu_var(wd_enabled) = 1; | |
265 | atomic_inc(&nmi_active); | |
266 | } | |
267 | } | |
268 | ||
269 | void stop_apic_nmi_watchdog(void *unused) | |
270 | { | |
271 | /* only support LOCAL and IO APICs for now */ | |
272 | if ((nmi_watchdog != NMI_LOCAL_APIC) && | |
273 | (nmi_watchdog != NMI_IO_APIC)) | |
274 | return; | |
275 | if (__get_cpu_var(wd_enabled) == 0) | |
276 | return; | |
277 | if (nmi_watchdog == NMI_LOCAL_APIC) | |
278 | lapic_watchdog_stop(); | |
279 | __get_cpu_var(wd_enabled) = 0; | |
280 | atomic_dec(&nmi_active); | |
281 | } | |
282 | ||
283 | /* | |
284 | * the best way to detect whether a CPU has a 'hard lockup' problem | |
285 | * is to check it's local APIC timer IRQ counts. If they are not | |
286 | * changing then that CPU has some problem. | |
287 | * | |
288 | * as these watchdog NMI IRQs are generated on every CPU, we only | |
289 | * have to check the current processor. | |
290 | */ | |
291 | ||
292 | static DEFINE_PER_CPU(unsigned, last_irq_sum); | |
293 | static DEFINE_PER_CPU(local_t, alert_counter); | |
294 | static DEFINE_PER_CPU(int, nmi_touch); | |
295 | ||
296 | void touch_nmi_watchdog(void) | |
297 | { | |
298 | if (nmi_watchdog > 0) { | |
299 | unsigned cpu; | |
300 | ||
301 | /* | |
302 | * Tell other CPUs to reset their alert counters. We cannot | |
303 | * do it ourselves because the alert count increase is not | |
304 | * atomic. | |
305 | */ | |
306 | for_each_present_cpu(cpu) { | |
307 | if (per_cpu(nmi_touch, cpu) != 1) | |
308 | per_cpu(nmi_touch, cpu) = 1; | |
309 | } | |
310 | } | |
311 | ||
312 | touch_softlockup_watchdog(); | |
313 | } | |
314 | EXPORT_SYMBOL(touch_nmi_watchdog); | |
315 | ||
316 | notrace __kprobes int | |
317 | nmi_watchdog_tick(struct pt_regs *regs, unsigned reason) | |
318 | { | |
319 | int sum; | |
320 | int touched = 0; | |
321 | int cpu = smp_processor_id(); | |
322 | int rc = 0; | |
323 | ||
324 | /* check for other users first */ | |
325 | if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) | |
326 | == NOTIFY_STOP) { | |
327 | rc = 1; | |
328 | touched = 1; | |
329 | } | |
330 | ||
331 | sum = read_pda(apic_timer_irqs) + read_pda(irq0_irqs); | |
332 | if (__get_cpu_var(nmi_touch)) { | |
333 | __get_cpu_var(nmi_touch) = 0; | |
334 | touched = 1; | |
335 | } | |
336 | ||
337 | if (cpu_isset(cpu, backtrace_mask)) { | |
338 | static DEFINE_SPINLOCK(lock); /* Serialise the printks */ | |
339 | ||
340 | spin_lock(&lock); | |
341 | printk("NMI backtrace for cpu %d\n", cpu); | |
342 | dump_stack(); | |
343 | spin_unlock(&lock); | |
344 | cpu_clear(cpu, backtrace_mask); | |
345 | } | |
346 | ||
347 | #ifdef CONFIG_X86_MCE | |
348 | /* Could check oops_in_progress here too, but it's safer | |
349 | not too */ | |
350 | if (atomic_read(&mce_entry) > 0) | |
351 | touched = 1; | |
352 | #endif | |
353 | /* if the apic timer isn't firing, this cpu isn't doing much */ | |
354 | if (!touched && __get_cpu_var(last_irq_sum) == sum) { | |
355 | /* | |
356 | * Ayiee, looks like this CPU is stuck ... | |
357 | * wait a few IRQs (5 seconds) before doing the oops ... | |
358 | */ | |
359 | local_inc(&__get_cpu_var(alert_counter)); | |
360 | if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz) | |
361 | die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs, | |
362 | panic_on_timeout); | |
363 | } else { | |
364 | __get_cpu_var(last_irq_sum) = sum; | |
365 | local_set(&__get_cpu_var(alert_counter), 0); | |
366 | } | |
367 | ||
368 | /* see if the nmi watchdog went off */ | |
369 | if (!__get_cpu_var(wd_enabled)) | |
370 | return rc; | |
371 | switch (nmi_watchdog) { | |
372 | case NMI_LOCAL_APIC: | |
373 | rc |= lapic_wd_event(nmi_hz); | |
374 | break; | |
375 | case NMI_IO_APIC: | |
376 | /* don't know how to accurately check for this. | |
377 | * just assume it was a watchdog timer interrupt | |
378 | * This matches the old behaviour. | |
379 | */ | |
380 | rc = 1; | |
381 | break; | |
382 | } | |
383 | return rc; | |
384 | } | |
385 | ||
386 | static unsigned ignore_nmis; | |
387 | ||
388 | asmlinkage notrace __kprobes void | |
389 | do_nmi(struct pt_regs *regs, long error_code) | |
390 | { | |
391 | nmi_enter(); | |
392 | add_pda(__nmi_count,1); | |
393 | if (!ignore_nmis) | |
394 | default_do_nmi(regs); | |
395 | nmi_exit(); | |
396 | } | |
397 | ||
398 | void stop_nmi(void) | |
399 | { | |
400 | acpi_nmi_disable(); | |
401 | ignore_nmis++; | |
402 | } | |
403 | ||
404 | void restart_nmi(void) | |
405 | { | |
406 | ignore_nmis--; | |
407 | acpi_nmi_enable(); | |
408 | } | |
409 | ||
410 | #ifdef CONFIG_SYSCTL | |
411 | ||
412 | static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu) | |
413 | { | |
414 | unsigned char reason = get_nmi_reason(); | |
415 | char buf[64]; | |
416 | ||
417 | sprintf(buf, "NMI received for unknown reason %02x\n", reason); | |
418 | die_nmi(buf, regs, 1); /* Always panic here */ | |
419 | return 0; | |
420 | } | |
421 | ||
422 | /* | |
423 | * proc handler for /proc/sys/kernel/nmi | |
424 | */ | |
425 | int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file, | |
426 | void __user *buffer, size_t *length, loff_t *ppos) | |
427 | { | |
428 | int old_state; | |
429 | ||
430 | nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0; | |
431 | old_state = nmi_watchdog_enabled; | |
432 | proc_dointvec(table, write, file, buffer, length, ppos); | |
433 | if (!!old_state == !!nmi_watchdog_enabled) | |
434 | return 0; | |
435 | ||
436 | if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) { | |
437 | printk( KERN_WARNING "NMI watchdog is permanently disabled\n"); | |
438 | return -EIO; | |
439 | } | |
440 | ||
441 | /* if nmi_watchdog is not set yet, then set it */ | |
442 | nmi_watchdog_default(); | |
443 | ||
444 | if (nmi_watchdog == NMI_LOCAL_APIC) { | |
445 | if (nmi_watchdog_enabled) | |
446 | enable_lapic_nmi_watchdog(); | |
447 | else | |
448 | disable_lapic_nmi_watchdog(); | |
449 | } else { | |
450 | printk( KERN_WARNING | |
451 | "NMI watchdog doesn't know what hardware to touch\n"); | |
452 | return -EIO; | |
453 | } | |
454 | return 0; | |
455 | } | |
456 | ||
457 | #endif | |
458 | ||
459 | int do_nmi_callback(struct pt_regs *regs, int cpu) | |
460 | { | |
461 | #ifdef CONFIG_SYSCTL | |
462 | if (unknown_nmi_panic) | |
463 | return unknown_nmi_panic_callback(regs, cpu); | |
464 | #endif | |
465 | return 0; | |
466 | } | |
467 | ||
468 | void __trigger_all_cpu_backtrace(void) | |
469 | { | |
470 | int i; | |
471 | ||
472 | backtrace_mask = cpu_online_map; | |
473 | /* Wait for up to 10 seconds for all CPUs to do the backtrace */ | |
474 | for (i = 0; i < 10 * 1000; i++) { | |
475 | if (cpus_empty(backtrace_mask)) | |
476 | break; | |
477 | mdelay(1); | |
478 | } | |
479 | } | |
480 | ||
481 | EXPORT_SYMBOL(nmi_active); | |
482 | EXPORT_SYMBOL(nmi_watchdog); |