2 * linux/arch/x86_64/nmi.c
4 * NMI watchdog support on APIC systems
6 * Started by Ingo Molnar <mingo@redhat.com>
9 * Mikael Pettersson : AMD K7 support for local APIC NMI watchdog.
10 * Mikael Pettersson : Power Management for local APIC NMI watchdog.
12 * Mikael Pettersson : PM converted to driver model. Disable/enable API.
15 #include <linux/config.h>
17 #include <linux/delay.h>
18 #include <linux/interrupt.h>
19 #include <linux/module.h>
20 #include <linux/sysdev.h>
21 #include <linux/nmi.h>
22 #include <linux/sysctl.h>
23 #include <linux/kprobes.h>
27 #include <asm/proto.h>
28 #include <asm/kdebug.h>
32 * lapic_nmi_owner tracks the ownership of the lapic NMI hardware:
33 * - it may be reserved by some other driver, or not
34 * - when not reserved by some other driver, it may be used for
35 * the NMI watchdog, or not
37 * This is maintained separately from nmi_active because the NMI
38 * watchdog may also be driven from the I/O APIC timer.
40 static DEFINE_SPINLOCK(lapic_nmi_owner_lock);
41 static unsigned int lapic_nmi_owner;
42 #define LAPIC_NMI_WATCHDOG (1<<0)
43 #define LAPIC_NMI_RESERVED (1<<1)
46 * +1: the lapic NMI watchdog is active, but can be disabled
47 * 0: the lapic NMI watchdog has not been set up, and cannot
49 * -1: the lapic NMI watchdog is disabled, but can be enabled
51 int nmi_active; /* oprofile uses this */
54 unsigned int nmi_watchdog = NMI_DEFAULT;
55 static unsigned int nmi_hz = HZ;
56 static unsigned int nmi_perfctr_msr; /* the MSR to reset in NMI handler */
57 static unsigned int nmi_p4_cccr_val;
59 /* Note that these events don't tick when the CPU idles. This means
60 the frequency varies with CPU load. */
62 #define K7_EVNTSEL_ENABLE (1 << 22)
63 #define K7_EVNTSEL_INT (1 << 20)
64 #define K7_EVNTSEL_OS (1 << 17)
65 #define K7_EVNTSEL_USR (1 << 16)
66 #define K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING 0x76
67 #define K7_NMI_EVENT K7_EVENT_CYCLES_PROCESSOR_IS_RUNNING
69 #define MSR_P4_MISC_ENABLE 0x1A0
70 #define MSR_P4_MISC_ENABLE_PERF_AVAIL (1<<7)
71 #define MSR_P4_MISC_ENABLE_PEBS_UNAVAIL (1<<12)
72 #define MSR_P4_PERFCTR0 0x300
73 #define MSR_P4_CCCR0 0x360
74 #define P4_ESCR_EVENT_SELECT(N) ((N)<<25)
75 #define P4_ESCR_OS (1<<3)
76 #define P4_ESCR_USR (1<<2)
77 #define P4_CCCR_OVF_PMI0 (1<<26)
78 #define P4_CCCR_OVF_PMI1 (1<<27)
79 #define P4_CCCR_THRESHOLD(N) ((N)<<20)
80 #define P4_CCCR_COMPLEMENT (1<<19)
81 #define P4_CCCR_COMPARE (1<<18)
82 #define P4_CCCR_REQUIRED (3<<16)
83 #define P4_CCCR_ESCR_SELECT(N) ((N)<<13)
84 #define P4_CCCR_ENABLE (1<<12)
85 /* Set up IQ_COUNTER0 to behave like a clock, by having IQ_CCCR0 filter
86 CRU_ESCR0 (with any non-null event selector) through a complemented
87 max threshold. [IA32-Vol3, Section 14.9.9] */
88 #define MSR_P4_IQ_COUNTER0 0x30C
89 #define P4_NMI_CRU_ESCR0 (P4_ESCR_EVENT_SELECT(0x3F)|P4_ESCR_OS|P4_ESCR_USR)
90 #define P4_NMI_IQ_CCCR0 \
91 (P4_CCCR_OVF_PMI0|P4_CCCR_THRESHOLD(15)|P4_CCCR_COMPLEMENT| \
92 P4_CCCR_COMPARE|P4_CCCR_REQUIRED|P4_CCCR_ESCR_SELECT(4)|P4_CCCR_ENABLE)
94 static __cpuinit inline int nmi_known_cpu(void)
96 switch (boot_cpu_data.x86_vendor) {
98 return boot_cpu_data.x86 == 15;
99 case X86_VENDOR_INTEL:
100 return boot_cpu_data.x86 == 15;
105 /* Run after command line and cpu_init init, but before all other checks */
106 void __cpuinit nmi_watchdog_default(void)
108 if (nmi_watchdog != NMI_DEFAULT)
111 nmi_watchdog = NMI_LOCAL_APIC;
113 nmi_watchdog = NMI_IO_APIC;
117 /* The performance counters used by NMI_LOCAL_APIC don't trigger when
118 * the CPU is idle. To make sure the NMI watchdog really ticks on all
119 * CPUs during the test make them busy.
121 static __init void nmi_cpu_busy(void *data)
123 volatile int *endflag = data;
125 /* Intentionally don't use cpu_relax here. This is
126 to make sure that the performance counter really ticks,
127 even if there is a simulator or similar that catches the
128 pause instruction. On a real HT machine this is fine because
129 all other CPUs are busy with "useless" delay loops and don't
130 care if they get somewhat less cycles. */
131 while (*endflag == 0)
136 int __init check_nmi_watchdog (void)
138 volatile int endflag = 0;
142 counts = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
146 printk(KERN_INFO "testing NMI watchdog ... ");
149 if (nmi_watchdog == NMI_LOCAL_APIC)
150 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
153 for (cpu = 0; cpu < NR_CPUS; cpu++)
154 counts[cpu] = cpu_pda(cpu)->__nmi_count;
156 mdelay((10*1000)/nmi_hz); // wait 10 ticks
158 for_each_online_cpu(cpu) {
159 if (cpu_pda(cpu)->__nmi_count - counts[cpu] <= 5) {
161 printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n",
164 cpu_pda(cpu)->__nmi_count);
166 lapic_nmi_owner &= ~LAPIC_NMI_WATCHDOG;
175 /* now that we know it works we can reduce NMI frequency to
176 something more reasonable; makes a difference in some configs */
177 if (nmi_watchdog == NMI_LOCAL_APIC)
184 int __init setup_nmi_watchdog(char *str)
188 if (!strncmp(str,"panic",5)) {
189 panic_on_timeout = 1;
190 str = strchr(str, ',');
196 get_option(&str, &nmi);
198 if (nmi >= NMI_INVALID)
204 __setup("nmi_watchdog=", setup_nmi_watchdog);
206 static void disable_lapic_nmi_watchdog(void)
210 switch (boot_cpu_data.x86_vendor) {
212 wrmsr(MSR_K7_EVNTSEL0, 0, 0);
214 case X86_VENDOR_INTEL:
215 if (boot_cpu_data.x86 == 15) {
216 wrmsr(MSR_P4_IQ_CCCR0, 0, 0);
217 wrmsr(MSR_P4_CRU_ESCR0, 0, 0);
222 /* tell do_nmi() and others that we're not active any more */
226 static void enable_lapic_nmi_watchdog(void)
228 if (nmi_active < 0) {
229 nmi_watchdog = NMI_LOCAL_APIC;
230 touch_nmi_watchdog();
231 setup_apic_nmi_watchdog();
235 int reserve_lapic_nmi(void)
237 unsigned int old_owner;
239 spin_lock(&lapic_nmi_owner_lock);
240 old_owner = lapic_nmi_owner;
241 lapic_nmi_owner |= LAPIC_NMI_RESERVED;
242 spin_unlock(&lapic_nmi_owner_lock);
243 if (old_owner & LAPIC_NMI_RESERVED)
245 if (old_owner & LAPIC_NMI_WATCHDOG)
246 disable_lapic_nmi_watchdog();
250 void release_lapic_nmi(void)
252 unsigned int new_owner;
254 spin_lock(&lapic_nmi_owner_lock);
255 new_owner = lapic_nmi_owner & ~LAPIC_NMI_RESERVED;
256 lapic_nmi_owner = new_owner;
257 spin_unlock(&lapic_nmi_owner_lock);
258 if (new_owner & LAPIC_NMI_WATCHDOG)
259 enable_lapic_nmi_watchdog();
262 void disable_timer_nmi_watchdog(void)
264 if ((nmi_watchdog != NMI_IO_APIC) || (nmi_active <= 0))
268 unset_nmi_callback();
270 nmi_watchdog = NMI_NONE;
273 void enable_timer_nmi_watchdog(void)
275 if (nmi_active < 0) {
276 nmi_watchdog = NMI_IO_APIC;
277 touch_nmi_watchdog();
285 static int nmi_pm_active; /* nmi_active before suspend */
287 static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
289 nmi_pm_active = nmi_active;
290 disable_lapic_nmi_watchdog();
294 static int lapic_nmi_resume(struct sys_device *dev)
296 if (nmi_pm_active > 0)
297 enable_lapic_nmi_watchdog();
301 static struct sysdev_class nmi_sysclass = {
302 set_kset_name("lapic_nmi"),
303 .resume = lapic_nmi_resume,
304 .suspend = lapic_nmi_suspend,
307 static struct sys_device device_lapic_nmi = {
309 .cls = &nmi_sysclass,
312 static int __init init_lapic_nmi_sysfs(void)
316 if (nmi_active == 0 || nmi_watchdog != NMI_LOCAL_APIC)
319 error = sysdev_class_register(&nmi_sysclass);
321 error = sysdev_register(&device_lapic_nmi);
324 /* must come after the local APIC's device_initcall() */
325 late_initcall(init_lapic_nmi_sysfs);
327 #endif /* CONFIG_PM */
330 * Activate the NMI watchdog via the local APIC.
331 * Original code written by Keith Owens.
334 static void clear_msr_range(unsigned int base, unsigned int n)
338 for(i = 0; i < n; ++i)
342 static void setup_k7_watchdog(void)
345 unsigned int evntsel;
347 nmi_perfctr_msr = MSR_K7_PERFCTR0;
349 for(i = 0; i < 4; ++i) {
350 /* Simulator may not support it */
351 if (checking_wrmsrl(MSR_K7_EVNTSEL0+i, 0UL)) {
355 wrmsrl(MSR_K7_PERFCTR0+i, 0UL);
358 evntsel = K7_EVNTSEL_INT
363 wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
364 wrmsrl(MSR_K7_PERFCTR0, -((u64)cpu_khz * 1000 / nmi_hz));
365 apic_write(APIC_LVTPC, APIC_DM_NMI);
366 evntsel |= K7_EVNTSEL_ENABLE;
367 wrmsr(MSR_K7_EVNTSEL0, evntsel, 0);
371 static int setup_p4_watchdog(void)
373 unsigned int misc_enable, dummy;
375 rdmsr(MSR_P4_MISC_ENABLE, misc_enable, dummy);
376 if (!(misc_enable & MSR_P4_MISC_ENABLE_PERF_AVAIL))
379 nmi_perfctr_msr = MSR_P4_IQ_COUNTER0;
380 nmi_p4_cccr_val = P4_NMI_IQ_CCCR0;
382 if (smp_num_siblings == 2)
383 nmi_p4_cccr_val |= P4_CCCR_OVF_PMI1;
386 if (!(misc_enable & MSR_P4_MISC_ENABLE_PEBS_UNAVAIL))
387 clear_msr_range(0x3F1, 2);
388 /* MSR 0x3F0 seems to have a default value of 0xFC00, but current
389 docs doesn't fully define it, so leave it alone for now. */
390 if (boot_cpu_data.x86_model >= 0x3) {
391 /* MSR_P4_IQ_ESCR0/1 (0x3ba/0x3bb) removed */
392 clear_msr_range(0x3A0, 26);
393 clear_msr_range(0x3BC, 3);
395 clear_msr_range(0x3A0, 31);
397 clear_msr_range(0x3C0, 6);
398 clear_msr_range(0x3C8, 6);
399 clear_msr_range(0x3E0, 2);
400 clear_msr_range(MSR_P4_CCCR0, 18);
401 clear_msr_range(MSR_P4_PERFCTR0, 18);
403 wrmsr(MSR_P4_CRU_ESCR0, P4_NMI_CRU_ESCR0, 0);
404 wrmsr(MSR_P4_IQ_CCCR0, P4_NMI_IQ_CCCR0 & ~P4_CCCR_ENABLE, 0);
405 Dprintk("setting P4_IQ_COUNTER0 to 0x%08lx\n", -(cpu_khz * 1000UL / nmi_hz));
406 wrmsrl(MSR_P4_IQ_COUNTER0, -((u64)cpu_khz * 1000 / nmi_hz));
407 apic_write(APIC_LVTPC, APIC_DM_NMI);
408 wrmsr(MSR_P4_IQ_CCCR0, nmi_p4_cccr_val, 0);
412 void setup_apic_nmi_watchdog(void)
414 switch (boot_cpu_data.x86_vendor) {
416 if (boot_cpu_data.x86 != 15)
418 if (strstr(boot_cpu_data.x86_model_id, "Screwdriver"))
422 case X86_VENDOR_INTEL:
423 if (boot_cpu_data.x86 != 15)
425 if (!setup_p4_watchdog())
432 lapic_nmi_owner = LAPIC_NMI_WATCHDOG;
437 * the best way to detect whether a CPU has a 'hard lockup' problem
438 * is to check it's local APIC timer IRQ counts. If they are not
439 * changing then that CPU has some problem.
441 * as these watchdog NMI IRQs are generated on every CPU, we only
442 * have to check the current processor.
445 static DEFINE_PER_CPU(unsigned, last_irq_sum);
446 static DEFINE_PER_CPU(local_t, alert_counter);
447 static DEFINE_PER_CPU(int, nmi_touch);
449 void touch_nmi_watchdog (void)
451 if (nmi_watchdog > 0) {
455 * Tell other CPUs to reset their alert counters. We cannot
456 * do it ourselves because the alert count increase is not
459 for_each_present_cpu (cpu)
460 per_cpu(nmi_touch, cpu) = 1;
463 touch_softlockup_watchdog();
466 void __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
471 sum = read_pda(apic_timer_irqs);
472 if (__get_cpu_var(nmi_touch)) {
473 __get_cpu_var(nmi_touch) = 0;
476 #ifdef CONFIG_X86_MCE
477 /* Could check oops_in_progress here too, but it's safer
479 if (atomic_read(&mce_entry) > 0)
482 if (!touched && __get_cpu_var(last_irq_sum) == sum) {
484 * Ayiee, looks like this CPU is stuck ...
485 * wait a few IRQs (5 seconds) before doing the oops ...
487 local_inc(&__get_cpu_var(alert_counter));
488 if (local_read(&__get_cpu_var(alert_counter)) == 5*nmi_hz) {
489 if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
491 local_set(&__get_cpu_var(alert_counter), 0);
494 die_nmi("NMI Watchdog detected LOCKUP on CPU %d\n", regs);
497 __get_cpu_var(last_irq_sum) = sum;
498 local_set(&__get_cpu_var(alert_counter), 0);
500 if (nmi_perfctr_msr) {
501 if (nmi_perfctr_msr == MSR_P4_IQ_COUNTER0) {
504 * - An overflown perfctr will assert its interrupt
505 * until the OVF flag in its CCCR is cleared.
506 * - LVTPC is masked on interrupt and must be
507 * unmasked by the LVTPC handler.
509 wrmsr(MSR_P4_IQ_CCCR0, nmi_p4_cccr_val, 0);
510 apic_write(APIC_LVTPC, APIC_DM_NMI);
512 wrmsrl(nmi_perfctr_msr, -((u64)cpu_khz * 1000 / nmi_hz));
516 static __kprobes int dummy_nmi_callback(struct pt_regs * regs, int cpu)
521 static nmi_callback_t nmi_callback = dummy_nmi_callback;
523 asmlinkage __kprobes void do_nmi(struct pt_regs * regs, long error_code)
525 int cpu = safe_smp_processor_id();
528 add_pda(__nmi_count,1);
529 if (!rcu_dereference(nmi_callback)(regs, cpu))
530 default_do_nmi(regs);
534 void set_nmi_callback(nmi_callback_t callback)
537 rcu_assign_pointer(nmi_callback, callback);
540 void unset_nmi_callback(void)
542 nmi_callback = dummy_nmi_callback;
547 static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
549 unsigned char reason = get_nmi_reason();
552 if (!(reason & 0xc0)) {
553 sprintf(buf, "NMI received for unknown reason %02x\n", reason);
560 * proc handler for /proc/sys/kernel/unknown_nmi_panic
562 int proc_unknown_nmi_panic(struct ctl_table *table, int write, struct file *file,
563 void __user *buffer, size_t *length, loff_t *ppos)
567 old_state = unknown_nmi_panic;
568 proc_dointvec(table, write, file, buffer, length, ppos);
569 if (!!old_state == !!unknown_nmi_panic)
572 if (unknown_nmi_panic) {
573 if (reserve_lapic_nmi() < 0) {
574 unknown_nmi_panic = 0;
577 set_nmi_callback(unknown_nmi_panic_callback);
581 unset_nmi_callback();
588 EXPORT_SYMBOL(nmi_active);
589 EXPORT_SYMBOL(nmi_watchdog);
590 EXPORT_SYMBOL(reserve_lapic_nmi);
591 EXPORT_SYMBOL(release_lapic_nmi);
592 EXPORT_SYMBOL(disable_timer_nmi_watchdog);
593 EXPORT_SYMBOL(enable_timer_nmi_watchdog);
594 EXPORT_SYMBOL(touch_nmi_watchdog);