Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6.26
[linux-2.6] / arch / x86 / kernel / nmi_64.c
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, 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 int __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
317 {
318         int sum;
319         int touched = 0;
320         int cpu = smp_processor_id();
321         int rc = 0;
322
323         /* check for other users first */
324         if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
325                         == NOTIFY_STOP) {
326                 rc = 1;
327                 touched = 1;
328         }
329
330         sum = read_pda(apic_timer_irqs) + read_pda(irq0_irqs);
331         if (__get_cpu_var(nmi_touch)) {
332                 __get_cpu_var(nmi_touch) = 0;
333                 touched = 1;
334         }
335
336         if (cpu_isset(cpu, backtrace_mask)) {
337                 static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
338
339                 spin_lock(&lock);
340                 printk("NMI backtrace for cpu %d\n", cpu);
341                 dump_stack();
342                 spin_unlock(&lock);
343                 cpu_clear(cpu, backtrace_mask);
344         }
345
346 #ifdef CONFIG_X86_MCE
347         /* Could check oops_in_progress here too, but it's safer
348            not too */
349         if (atomic_read(&mce_entry) > 0)
350                 touched = 1;
351 #endif
352         /* if the apic timer isn't firing, this cpu isn't doing much */
353         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
354                 /*
355                  * Ayiee, looks like this CPU is stuck ...
356                  * wait a few IRQs (5 seconds) before doing the oops ...
357                  */
358                 local_inc(&__get_cpu_var(alert_counter));
359                 if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz)
360                         die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs,
361                                 panic_on_timeout);
362         } else {
363                 __get_cpu_var(last_irq_sum) = sum;
364                 local_set(&__get_cpu_var(alert_counter), 0);
365         }
366
367         /* see if the nmi watchdog went off */
368         if (!__get_cpu_var(wd_enabled))
369                 return rc;
370         switch (nmi_watchdog) {
371         case NMI_LOCAL_APIC:
372                 rc |= lapic_wd_event(nmi_hz);
373                 break;
374         case NMI_IO_APIC:
375                 /* don't know how to accurately check for this.
376                  * just assume it was a watchdog timer interrupt
377                  * This matches the old behaviour.
378                  */
379                 rc = 1;
380                 break;
381         }
382         return rc;
383 }
384
385 static unsigned ignore_nmis;
386
387 asmlinkage __kprobes void do_nmi(struct pt_regs * regs, long error_code)
388 {
389         nmi_enter();
390         add_pda(__nmi_count,1);
391         if (!ignore_nmis)
392                 default_do_nmi(regs);
393         nmi_exit();
394 }
395
396 void stop_nmi(void)
397 {
398         acpi_nmi_disable();
399         ignore_nmis++;
400 }
401
402 void restart_nmi(void)
403 {
404         ignore_nmis--;
405         acpi_nmi_enable();
406 }
407
408 #ifdef CONFIG_SYSCTL
409
410 static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
411 {
412         unsigned char reason = get_nmi_reason();
413         char buf[64];
414
415         sprintf(buf, "NMI received for unknown reason %02x\n", reason);
416         die_nmi(buf, regs, 1);  /* Always panic here */
417         return 0;
418 }
419
420 /*
421  * proc handler for /proc/sys/kernel/nmi
422  */
423 int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
424                         void __user *buffer, size_t *length, loff_t *ppos)
425 {
426         int old_state;
427
428         nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;
429         old_state = nmi_watchdog_enabled;
430         proc_dointvec(table, write, file, buffer, length, ppos);
431         if (!!old_state == !!nmi_watchdog_enabled)
432                 return 0;
433
434         if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) {
435                 printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
436                 return -EIO;
437         }
438
439         /* if nmi_watchdog is not set yet, then set it */
440         nmi_watchdog_default();
441
442         if (nmi_watchdog == NMI_LOCAL_APIC) {
443                 if (nmi_watchdog_enabled)
444                         enable_lapic_nmi_watchdog();
445                 else
446                         disable_lapic_nmi_watchdog();
447         } else {
448                 printk( KERN_WARNING
449                         "NMI watchdog doesn't know what hardware to touch\n");
450                 return -EIO;
451         }
452         return 0;
453 }
454
455 #endif
456
457 int do_nmi_callback(struct pt_regs *regs, int cpu)
458 {
459 #ifdef CONFIG_SYSCTL
460         if (unknown_nmi_panic)
461                 return unknown_nmi_panic_callback(regs, cpu);
462 #endif
463         return 0;
464 }
465
466 void __trigger_all_cpu_backtrace(void)
467 {
468         int i;
469
470         backtrace_mask = cpu_online_map;
471         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
472         for (i = 0; i < 10 * 1000; i++) {
473                 if (cpus_empty(backtrace_mask))
474                         break;
475                 mdelay(1);
476         }
477 }
478
479 EXPORT_SYMBOL(nmi_active);
480 EXPORT_SYMBOL(nmi_watchdog);