x86: fix compile warning building without CONFIG_SYSCTL
[sfrench/cifs-2.6.git] / 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 int unknown_nmi_panic;
30 int nmi_watchdog_enabled;
31 int panic_on_unrecovered_nmi;
32
33 static cpumask_t backtrace_mask = CPU_MASK_NONE;
34
35 /* nmi_active:
36  * >0: the lapic NMI watchdog is active, but can be disabled
37  * <0: the lapic NMI watchdog has not been set up, and cannot
38  *     be enabled
39  *  0: the lapic NMI watchdog is disabled, but can be enabled
40  */
41 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
42 static int panic_on_timeout;
43
44 unsigned int nmi_watchdog = NMI_DEFAULT;
45 static unsigned int nmi_hz = HZ;
46
47 static DEFINE_PER_CPU(short, wd_enabled);
48
49 /* Run after command line and cpu_init init, but before all other checks */
50 void nmi_watchdog_default(void)
51 {
52         if (nmi_watchdog != NMI_DEFAULT)
53                 return;
54         nmi_watchdog = NMI_NONE;
55 }
56
57 static int endflag __initdata = 0;
58
59 #ifdef CONFIG_SMP
60 /* The performance counters used by NMI_LOCAL_APIC don't trigger when
61  * the CPU is idle. To make sure the NMI watchdog really ticks on all
62  * CPUs during the test make them busy.
63  */
64 static __init void nmi_cpu_busy(void *data)
65 {
66         local_irq_enable_in_hardirq();
67         /* Intentionally don't use cpu_relax here. This is
68            to make sure that the performance counter really ticks,
69            even if there is a simulator or similar that catches the
70            pause instruction. On a real HT machine this is fine because
71            all other CPUs are busy with "useless" delay loops and don't
72            care if they get somewhat less cycles. */
73         while (endflag == 0)
74                 mb();
75 }
76 #endif
77
78 int __init check_nmi_watchdog(void)
79 {
80         int *prev_nmi_count;
81         int cpu;
82
83         if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED))
84                 return 0;
85
86         if (!atomic_read(&nmi_active))
87                 return 0;
88
89         prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
90         if (!prev_nmi_count)
91                 return -1;
92
93         printk(KERN_INFO "Testing NMI watchdog ... ");
94
95 #ifdef CONFIG_SMP
96         if (nmi_watchdog == NMI_LOCAL_APIC)
97                 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
98 #endif
99
100         for (cpu = 0; cpu < NR_CPUS; cpu++)
101                 prev_nmi_count[cpu] = cpu_pda(cpu)->__nmi_count;
102         local_irq_enable();
103         mdelay((20*1000)/nmi_hz); // wait 20 ticks
104
105         for_each_online_cpu(cpu) {
106                 if (!per_cpu(wd_enabled, cpu))
107                         continue;
108                 if (cpu_pda(cpu)->__nmi_count - prev_nmi_count[cpu] <= 5) {
109                         printk(KERN_WARNING "WARNING: CPU#%d: NMI "
110                                "appears to be stuck (%d->%d)!\n",
111                                 cpu,
112                                 prev_nmi_count[cpu],
113                                 cpu_pda(cpu)->__nmi_count);
114                         per_cpu(wd_enabled, cpu) = 0;
115                         atomic_dec(&nmi_active);
116                 }
117         }
118         endflag = 1;
119         if (!atomic_read(&nmi_active)) {
120                 kfree(prev_nmi_count);
121                 atomic_set(&nmi_active, -1);
122                 return -1;
123         }
124         printk("OK.\n");
125
126         /* now that we know it works we can reduce NMI frequency to
127            something more reasonable; makes a difference in some configs */
128         if (nmi_watchdog == NMI_LOCAL_APIC)
129                 nmi_hz = lapic_adjust_nmi_hz(1);
130
131         kfree(prev_nmi_count);
132         return 0;
133 }
134
135 static int __init setup_nmi_watchdog(char *str)
136 {
137         int nmi;
138
139         if (!strncmp(str,"panic",5)) {
140                 panic_on_timeout = 1;
141                 str = strchr(str, ',');
142                 if (!str)
143                         return 1;
144                 ++str;
145         }
146
147         get_option(&str, &nmi);
148
149         if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE))
150                 return 0;
151
152         nmi_watchdog = nmi;
153         return 1;
154 }
155
156 __setup("nmi_watchdog=", setup_nmi_watchdog);
157
158 #ifdef CONFIG_PM
159
160 static int nmi_pm_active; /* nmi_active before suspend */
161
162 static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
163 {
164         /* only CPU0 goes here, other CPUs should be offline */
165         nmi_pm_active = atomic_read(&nmi_active);
166         stop_apic_nmi_watchdog(NULL);
167         BUG_ON(atomic_read(&nmi_active) != 0);
168         return 0;
169 }
170
171 static int lapic_nmi_resume(struct sys_device *dev)
172 {
173         /* only CPU0 goes here, other CPUs should be offline */
174         if (nmi_pm_active > 0) {
175                 setup_apic_nmi_watchdog(NULL);
176                 touch_nmi_watchdog();
177         }
178         return 0;
179 }
180
181 static struct sysdev_class nmi_sysclass = {
182         .name           = "lapic_nmi",
183         .resume         = lapic_nmi_resume,
184         .suspend        = lapic_nmi_suspend,
185 };
186
187 static struct sys_device device_lapic_nmi = {
188         .id     = 0,
189         .cls    = &nmi_sysclass,
190 };
191
192 static int __init init_lapic_nmi_sysfs(void)
193 {
194         int error;
195
196         /* should really be a BUG_ON but b/c this is an
197          * init call, it just doesn't work.  -dcz
198          */
199         if (nmi_watchdog != NMI_LOCAL_APIC)
200                 return 0;
201
202         if (atomic_read(&nmi_active) < 0)
203                 return 0;
204
205         error = sysdev_class_register(&nmi_sysclass);
206         if (!error)
207                 error = sysdev_register(&device_lapic_nmi);
208         return error;
209 }
210 /* must come after the local APIC's device_initcall() */
211 late_initcall(init_lapic_nmi_sysfs);
212
213 #endif  /* CONFIG_PM */
214
215 static void __acpi_nmi_enable(void *__unused)
216 {
217         apic_write(APIC_LVT0, APIC_DM_NMI);
218 }
219
220 /*
221  * Enable timer based NMIs on all CPUs:
222  */
223 void acpi_nmi_enable(void)
224 {
225         if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
226                 on_each_cpu(__acpi_nmi_enable, NULL, 0, 1);
227 }
228
229 static void __acpi_nmi_disable(void *__unused)
230 {
231         apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
232 }
233
234 /*
235  * Disable timer based NMIs on all CPUs:
236  */
237 void acpi_nmi_disable(void)
238 {
239         if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
240                 on_each_cpu(__acpi_nmi_disable, NULL, 0, 1);
241 }
242
243 void setup_apic_nmi_watchdog(void *unused)
244 {
245         if (__get_cpu_var(wd_enabled))
246                 return;
247
248         /* cheap hack to support suspend/resume */
249         /* if cpu0 is not active neither should the other cpus */
250         if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0))
251                 return;
252
253         switch (nmi_watchdog) {
254         case NMI_LOCAL_APIC:
255                 __get_cpu_var(wd_enabled) = 1;
256                 if (lapic_watchdog_init(nmi_hz) < 0) {
257                         __get_cpu_var(wd_enabled) = 0;
258                         return;
259                 }
260                 /* FALL THROUGH */
261         case NMI_IO_APIC:
262                 __get_cpu_var(wd_enabled) = 1;
263                 atomic_inc(&nmi_active);
264         }
265 }
266
267 void stop_apic_nmi_watchdog(void *unused)
268 {
269         /* only support LOCAL and IO APICs for now */
270         if ((nmi_watchdog != NMI_LOCAL_APIC) &&
271             (nmi_watchdog != NMI_IO_APIC))
272                 return;
273         if (__get_cpu_var(wd_enabled) == 0)
274                 return;
275         if (nmi_watchdog == NMI_LOCAL_APIC)
276                 lapic_watchdog_stop();
277         __get_cpu_var(wd_enabled) = 0;
278         atomic_dec(&nmi_active);
279 }
280
281 /*
282  * the best way to detect whether a CPU has a 'hard lockup' problem
283  * is to check it's local APIC timer IRQ counts. If they are not
284  * changing then that CPU has some problem.
285  *
286  * as these watchdog NMI IRQs are generated on every CPU, we only
287  * have to check the current processor.
288  */
289
290 static DEFINE_PER_CPU(unsigned, last_irq_sum);
291 static DEFINE_PER_CPU(local_t, alert_counter);
292 static DEFINE_PER_CPU(int, nmi_touch);
293
294 void touch_nmi_watchdog(void)
295 {
296         if (nmi_watchdog > 0) {
297                 unsigned cpu;
298
299                 /*
300                  * Tell other CPUs to reset their alert counters. We cannot
301                  * do it ourselves because the alert count increase is not
302                  * atomic.
303                  */
304                 for_each_present_cpu(cpu) {
305                         if (per_cpu(nmi_touch, cpu) != 1)
306                                 per_cpu(nmi_touch, cpu) = 1;
307                 }
308         }
309
310         touch_softlockup_watchdog();
311 }
312 EXPORT_SYMBOL(touch_nmi_watchdog);
313
314 int __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
315 {
316         int sum;
317         int touched = 0;
318         int cpu = smp_processor_id();
319         int rc = 0;
320
321         /* check for other users first */
322         if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
323                         == NOTIFY_STOP) {
324                 rc = 1;
325                 touched = 1;
326         }
327
328         sum = read_pda(apic_timer_irqs) + read_pda(irq0_irqs);
329         if (__get_cpu_var(nmi_touch)) {
330                 __get_cpu_var(nmi_touch) = 0;
331                 touched = 1;
332         }
333
334         if (cpu_isset(cpu, backtrace_mask)) {
335                 static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
336
337                 spin_lock(&lock);
338                 printk("NMI backtrace for cpu %d\n", cpu);
339                 dump_stack();
340                 spin_unlock(&lock);
341                 cpu_clear(cpu, backtrace_mask);
342         }
343
344 #ifdef CONFIG_X86_MCE
345         /* Could check oops_in_progress here too, but it's safer
346            not too */
347         if (atomic_read(&mce_entry) > 0)
348                 touched = 1;
349 #endif
350         /* if the apic timer isn't firing, this cpu isn't doing much */
351         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
352                 /*
353                  * Ayiee, looks like this CPU is stuck ...
354                  * wait a few IRQs (5 seconds) before doing the oops ...
355                  */
356                 local_inc(&__get_cpu_var(alert_counter));
357                 if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz)
358                         die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs,
359                                 panic_on_timeout);
360         } else {
361                 __get_cpu_var(last_irq_sum) = sum;
362                 local_set(&__get_cpu_var(alert_counter), 0);
363         }
364
365         /* see if the nmi watchdog went off */
366         if (!__get_cpu_var(wd_enabled))
367                 return rc;
368         switch (nmi_watchdog) {
369         case NMI_LOCAL_APIC:
370                 rc |= lapic_wd_event(nmi_hz);
371                 break;
372         case NMI_IO_APIC:
373                 /* don't know how to accurately check for this.
374                  * just assume it was a watchdog timer interrupt
375                  * This matches the old behaviour.
376                  */
377                 rc = 1;
378                 break;
379         }
380         return rc;
381 }
382
383 static unsigned ignore_nmis;
384
385 asmlinkage __kprobes void do_nmi(struct pt_regs * regs, long error_code)
386 {
387         nmi_enter();
388         add_pda(__nmi_count,1);
389         if (!ignore_nmis)
390                 default_do_nmi(regs);
391         nmi_exit();
392 }
393
394 void stop_nmi(void)
395 {
396         acpi_nmi_disable();
397         ignore_nmis++;
398 }
399
400 void restart_nmi(void)
401 {
402         ignore_nmis--;
403         acpi_nmi_enable();
404 }
405
406 #ifdef CONFIG_SYSCTL
407
408 static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
409 {
410         unsigned char reason = get_nmi_reason();
411         char buf[64];
412
413         sprintf(buf, "NMI received for unknown reason %02x\n", reason);
414         die_nmi(buf, regs, 1);  /* Always panic here */
415         return 0;
416 }
417
418 /*
419  * proc handler for /proc/sys/kernel/nmi
420  */
421 int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
422                         void __user *buffer, size_t *length, loff_t *ppos)
423 {
424         int old_state;
425
426         nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;
427         old_state = nmi_watchdog_enabled;
428         proc_dointvec(table, write, file, buffer, length, ppos);
429         if (!!old_state == !!nmi_watchdog_enabled)
430                 return 0;
431
432         if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) {
433                 printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
434                 return -EIO;
435         }
436
437         /* if nmi_watchdog is not set yet, then set it */
438         nmi_watchdog_default();
439
440         if (nmi_watchdog == NMI_LOCAL_APIC) {
441                 if (nmi_watchdog_enabled)
442                         enable_lapic_nmi_watchdog();
443                 else
444                         disable_lapic_nmi_watchdog();
445         } else {
446                 printk( KERN_WARNING
447                         "NMI watchdog doesn't know what hardware to touch\n");
448                 return -EIO;
449         }
450         return 0;
451 }
452
453 #endif
454
455 int do_nmi_callback(struct pt_regs *regs, int cpu)
456 {
457 #ifdef CONFIG_SYSCTL
458         if (unknown_nmi_panic)
459                 return unknown_nmi_panic_callback(regs, cpu);
460 #endif
461         return 0;
462 }
463
464 void __trigger_all_cpu_backtrace(void)
465 {
466         int i;
467
468         backtrace_mask = cpu_online_map;
469         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
470         for (i = 0; i < 10 * 1000; i++) {
471                 if (cpus_empty(backtrace_mask))
472                         break;
473                 mdelay(1);
474         }
475 }
476
477 EXPORT_SYMBOL(nmi_active);
478 EXPORT_SYMBOL(nmi_watchdog);