2 * Machine check handler.
3 * K8 parts Copyright 2002,2003 Andi Kleen, SuSE Labs.
4 * Rest from unknown author(s).
5 * 2004 Andi Kleen. Rewrote most of it.
8 #include <linux/init.h>
9 #include <linux/types.h>
10 #include <linux/kernel.h>
11 #include <linux/sched.h>
12 #include <linux/smp_lock.h>
13 #include <linux/string.h>
14 #include <linux/rcupdate.h>
15 #include <linux/kallsyms.h>
16 #include <linux/sysdev.h>
17 #include <linux/miscdevice.h>
19 #include <linux/capability.h>
20 #include <linux/cpu.h>
21 #include <linux/percpu.h>
22 #include <linux/poll.h>
23 #include <linux/thread_info.h>
24 #include <linux/ctype.h>
25 #include <linux/kmod.h>
26 #include <linux/kdebug.h>
27 #include <asm/processor.h>
30 #include <asm/uaccess.h>
34 #define MISC_MCELOG_MINOR 227
39 static int mce_dont_init;
43 * 0: always panic on uncorrected errors, log corrected errors
44 * 1: panic or SIGBUS on uncorrected errors, log corrected errors
45 * 2: SIGBUS or log uncorrected errors (if possible), log corrected errors
46 * 3: never panic or SIGBUS, log all errors (for testing only)
48 static int tolerant = 1;
50 static unsigned long bank[NR_BANKS] = { [0 ... NR_BANKS-1] = ~0UL };
51 static unsigned long notify_user;
53 static int mce_bootlog = -1;
54 static atomic_t mce_events;
56 static char trigger[128];
57 static char *trigger_argv[2] = { trigger, NULL };
59 static DECLARE_WAIT_QUEUE_HEAD(mce_wait);
62 * Lockless MCE logging infrastructure.
63 * This avoids deadlocks on printk locks without having to break locks. Also
64 * separate MCEs from kernel messages to avoid bogus bug reports.
67 static struct mce_log mcelog = {
72 void mce_log(struct mce *mce)
75 atomic_inc(&mce_events);
79 entry = rcu_dereference(mcelog.next);
81 /* When the buffer fills up discard new entries. Assume
82 that the earlier errors are the more interesting. */
83 if (entry >= MCE_LOG_LEN) {
84 set_bit(MCE_OVERFLOW, (unsigned long *)&mcelog.flags);
87 /* Old left over entry. Skip. */
88 if (mcelog.entry[entry].finished) {
96 if (cmpxchg(&mcelog.next, entry, next) == entry)
99 memcpy(mcelog.entry + entry, mce, sizeof(struct mce));
101 mcelog.entry[entry].finished = 1;
104 set_bit(0, ¬ify_user);
107 static void print_mce(struct mce *m)
109 printk(KERN_EMERG "\n"
110 KERN_EMERG "HARDWARE ERROR\n"
112 "CPU %d: Machine Check Exception: %16Lx Bank %d: %016Lx\n",
113 m->cpu, m->mcgstatus, m->bank, m->status);
115 printk(KERN_EMERG "RIP%s %02x:<%016Lx> ",
116 !(m->mcgstatus & MCG_STATUS_EIPV) ? " !INEXACT!" : "",
118 if (m->cs == __KERNEL_CS)
119 print_symbol("{%s}", m->ip);
122 printk(KERN_EMERG "TSC %Lx ", m->tsc);
124 printk("ADDR %Lx ", m->addr);
126 printk("MISC %Lx ", m->misc);
128 printk(KERN_EMERG "This is not a software problem!\n");
129 printk(KERN_EMERG "Run through mcelog --ascii to decode "
130 "and contact your hardware vendor\n");
133 static void mce_panic(char *msg, struct mce *backup, unsigned long start)
138 for (i = 0; i < MCE_LOG_LEN; i++) {
139 unsigned long tsc = mcelog.entry[i].tsc;
141 if (time_before(tsc, start))
143 print_mce(&mcelog.entry[i]);
144 if (backup && mcelog.entry[i].tsc == backup->tsc)
152 static int mce_available(struct cpuinfo_x86 *c)
154 return cpu_has(c, X86_FEATURE_MCE) && cpu_has(c, X86_FEATURE_MCA);
157 static inline void mce_get_rip(struct mce *m, struct pt_regs *regs)
159 if (regs && (m->mcgstatus & MCG_STATUS_RIPV)) {
167 /* Assume the RIP in the MSR is exact. Is this true? */
168 m->mcgstatus |= MCG_STATUS_EIPV;
169 rdmsrl(rip_msr, m->ip);
175 * The actual machine check handler
177 void do_machine_check(struct pt_regs * regs, long error_code)
179 struct mce m, panicm;
182 int panicm_found = 0;
184 * If no_way_out gets set, there is no safe way to recover from this
185 * MCE. If tolerant is cranked up, we'll try anyway.
189 * If kill_it gets set, there might be a way to recover from this
194 atomic_inc(&mce_entry);
197 && notify_die(DIE_NMI, "machine check", regs, error_code,
198 18, SIGKILL) == NOTIFY_STOP)
202 memset(&m, 0, sizeof(struct mce));
203 m.cpu = smp_processor_id();
204 rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
205 /* if the restart IP is not valid, we're done for */
206 if (!(m.mcgstatus & MCG_STATUS_RIPV))
212 for (i = 0; i < banks; i++) {
221 rdmsrl(MSR_IA32_MC0_STATUS + i*4, m.status);
222 if ((m.status & MCI_STATUS_VAL) == 0)
225 if (m.status & MCI_STATUS_EN) {
226 /* if PCC was set, there's no way out */
227 no_way_out |= !!(m.status & MCI_STATUS_PCC);
229 * If this error was uncorrectable and there was
230 * an overflow, we're in trouble. If no overflow,
231 * we might get away with just killing a task.
233 if (m.status & MCI_STATUS_UC) {
234 if (tolerant < 1 || m.status & MCI_STATUS_OVER)
240 if (m.status & MCI_STATUS_MISCV)
241 rdmsrl(MSR_IA32_MC0_MISC + i*4, m.misc);
242 if (m.status & MCI_STATUS_ADDRV)
243 rdmsrl(MSR_IA32_MC0_ADDR + i*4, m.addr);
245 mce_get_rip(&m, regs);
248 if (error_code != -2)
251 /* Did this bank cause the exception? */
252 /* Assume that the bank with uncorrectable errors did it,
253 and that there is only a single one. */
254 if ((m.status & MCI_STATUS_UC) && (m.status & MCI_STATUS_EN)) {
259 add_taint(TAINT_MACHINE_CHECK);
262 /* Never do anything final in the polling timer */
266 /* If we didn't find an uncorrectable error, pick
267 the last one (shouldn't happen, just being safe). */
272 * If we have decided that we just CAN'T continue, and the user
273 * has not set tolerant to an insane level, give up and die.
275 if (no_way_out && tolerant < 3)
276 mce_panic("Machine check", &panicm, mcestart);
279 * If the error seems to be unrecoverable, something should be
280 * done. Try to kill as little as possible. If we can kill just
281 * one task, do that. If the user has set the tolerance very
282 * high, don't try to do anything at all.
284 if (kill_it && tolerant < 3) {
288 * If the EIPV bit is set, it means the saved IP is the
289 * instruction which caused the MCE.
291 if (m.mcgstatus & MCG_STATUS_EIPV)
292 user_space = panicm.ip && (panicm.cs & 3);
295 * If we know that the error was in user space, send a
296 * SIGBUS. Otherwise, panic if tolerance is low.
298 * do_exit() takes an awful lot of locks and has a slight
299 * risk of deadlocking.
303 } else if (panic_on_oops || tolerant < 2) {
304 mce_panic("Uncorrected machine check",
309 /* notify userspace ASAP */
310 set_thread_flag(TIF_MCE_NOTIFY);
313 /* the last thing we do is clear state */
314 for (i = 0; i < banks; i++)
315 wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
316 wrmsrl(MSR_IA32_MCG_STATUS, 0);
318 atomic_dec(&mce_entry);
321 #ifdef CONFIG_X86_MCE_INTEL
323 * mce_log_therm_throt_event - Logs the thermal throttling event to mcelog
324 * @cpu: The CPU on which the event occurred.
325 * @status: Event status information
327 * This function should be called by the thermal interrupt after the
328 * event has been processed and the decision was made to log the event
331 * The status parameter will be saved to the 'status' field of 'struct mce'
332 * and historically has been the register value of the
333 * MSR_IA32_THERMAL_STATUS (Intel) msr.
335 void mce_log_therm_throt_event(unsigned int cpu, __u64 status)
339 memset(&m, 0, sizeof(m));
341 m.bank = MCE_THERMAL_BANK;
346 #endif /* CONFIG_X86_MCE_INTEL */
349 * Periodic polling timer for "silent" machine check errors. If the
350 * poller finds an MCE, poll 2x faster. When the poller finds no more
351 * errors, poll 2x slower (up to check_interval seconds).
354 static int check_interval = 5 * 60; /* 5 minutes */
355 static int next_interval; /* in jiffies */
356 static void mcheck_timer(struct work_struct *work);
357 static DECLARE_DELAYED_WORK(mcheck_work, mcheck_timer);
359 static void mcheck_check_cpu(void *info)
361 if (mce_available(¤t_cpu_data))
362 do_machine_check(NULL, 0);
365 static void mcheck_timer(struct work_struct *work)
367 on_each_cpu(mcheck_check_cpu, NULL, 1, 1);
370 * Alert userspace if needed. If we logged an MCE, reduce the
371 * polling interval, otherwise increase the polling interval.
373 if (mce_notify_user()) {
374 next_interval = max(next_interval/2, HZ/100);
376 next_interval = min(next_interval * 2,
377 (int)round_jiffies_relative(check_interval*HZ));
380 schedule_delayed_work(&mcheck_work, next_interval);
384 * This is only called from process context. This is where we do
385 * anything we need to alert userspace about new MCEs. This is called
386 * directly from the poller and also from entry.S and idle, thanks to
389 int mce_notify_user(void)
391 clear_thread_flag(TIF_MCE_NOTIFY);
392 if (test_and_clear_bit(0, ¬ify_user)) {
393 static unsigned long last_print;
394 unsigned long now = jiffies;
396 wake_up_interruptible(&mce_wait);
398 call_usermodehelper(trigger, trigger_argv, NULL,
401 if (time_after_eq(now, last_print + (check_interval*HZ))) {
403 printk(KERN_INFO "Machine check events logged\n");
411 /* see if the idle task needs to notify userspace */
413 mce_idle_callback(struct notifier_block *nfb, unsigned long action, void *junk)
415 /* IDLE_END should be safe - interrupts are back on */
416 if (action == IDLE_END && test_thread_flag(TIF_MCE_NOTIFY))
422 static struct notifier_block mce_idle_notifier = {
423 .notifier_call = mce_idle_callback,
426 static __init int periodic_mcheck_init(void)
428 next_interval = check_interval * HZ;
430 schedule_delayed_work(&mcheck_work,
431 round_jiffies_relative(next_interval));
432 idle_notifier_register(&mce_idle_notifier);
435 __initcall(periodic_mcheck_init);
439 * Initialize Machine Checks for a CPU.
441 static void mce_init(void *dummy)
446 rdmsrl(MSR_IA32_MCG_CAP, cap);
448 if (banks > NR_BANKS) {
449 printk(KERN_INFO "MCE: warning: using only %d banks\n", banks);
452 /* Use accurate RIP reporting if available. */
453 if ((cap & (1<<9)) && ((cap >> 16) & 0xff) >= 9)
454 rip_msr = MSR_IA32_MCG_EIP;
456 /* Log the machine checks left over from the previous reset.
457 This also clears all registers */
458 do_machine_check(NULL, mce_bootlog ? -1 : -2);
460 set_in_cr4(X86_CR4_MCE);
463 wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff);
465 for (i = 0; i < banks; i++) {
466 wrmsrl(MSR_IA32_MC0_CTL+4*i, bank[i]);
467 wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
471 /* Add per CPU specific workarounds here */
472 static void __cpuinit mce_cpu_quirks(struct cpuinfo_x86 *c)
474 /* This should be disabled by the BIOS, but isn't always */
475 if (c->x86_vendor == X86_VENDOR_AMD) {
477 /* disable GART TBL walk error reporting, which trips off
478 incorrectly with the IOMMU & 3ware & Cerberus. */
479 clear_bit(10, &bank[4]);
480 if(c->x86 <= 17 && mce_bootlog < 0)
481 /* Lots of broken BIOS around that don't clear them
482 by default and leave crap in there. Don't log. */
488 static void __cpuinit mce_cpu_features(struct cpuinfo_x86 *c)
490 switch (c->x86_vendor) {
491 case X86_VENDOR_INTEL:
492 mce_intel_feature_init(c);
495 mce_amd_feature_init(c);
503 * Called for each booted CPU to set up machine checks.
504 * Must be called with preempt off.
506 void __cpuinit mcheck_init(struct cpuinfo_x86 *c)
508 static cpumask_t mce_cpus = CPU_MASK_NONE;
513 cpu_test_and_set(smp_processor_id(), mce_cpus) ||
522 * Character device to read and clear the MCE log.
525 static DEFINE_SPINLOCK(mce_state_lock);
526 static int open_count; /* #times opened */
527 static int open_exclu; /* already open exclusive? */
529 static int mce_open(struct inode *inode, struct file *file)
532 spin_lock(&mce_state_lock);
534 if (open_exclu || (open_count && (file->f_flags & O_EXCL))) {
535 spin_unlock(&mce_state_lock);
540 if (file->f_flags & O_EXCL)
544 spin_unlock(&mce_state_lock);
547 return nonseekable_open(inode, file);
550 static int mce_release(struct inode *inode, struct file *file)
552 spin_lock(&mce_state_lock);
557 spin_unlock(&mce_state_lock);
562 static void collect_tscs(void *data)
564 unsigned long *cpu_tsc = (unsigned long *)data;
566 rdtscll(cpu_tsc[smp_processor_id()]);
569 static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize,
572 unsigned long *cpu_tsc;
573 static DEFINE_MUTEX(mce_read_mutex);
575 char __user *buf = ubuf;
578 cpu_tsc = kmalloc(NR_CPUS * sizeof(long), GFP_KERNEL);
582 mutex_lock(&mce_read_mutex);
583 next = rcu_dereference(mcelog.next);
585 /* Only supports full reads right now */
586 if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce)) {
587 mutex_unlock(&mce_read_mutex);
593 for (i = 0; i < next; i++) {
594 unsigned long start = jiffies;
596 while (!mcelog.entry[i].finished) {
597 if (time_after_eq(jiffies, start + 2)) {
598 memset(mcelog.entry + i,0, sizeof(struct mce));
604 err |= copy_to_user(buf, mcelog.entry + i, sizeof(struct mce));
605 buf += sizeof(struct mce);
610 memset(mcelog.entry, 0, next * sizeof(struct mce));
616 * Collect entries that were still getting written before the
619 on_each_cpu(collect_tscs, cpu_tsc, 1, 1);
620 for (i = next; i < MCE_LOG_LEN; i++) {
621 if (mcelog.entry[i].finished &&
622 mcelog.entry[i].tsc < cpu_tsc[mcelog.entry[i].cpu]) {
623 err |= copy_to_user(buf, mcelog.entry+i,
626 buf += sizeof(struct mce);
627 memset(&mcelog.entry[i], 0, sizeof(struct mce));
630 mutex_unlock(&mce_read_mutex);
632 return err ? -EFAULT : buf - ubuf;
635 static unsigned int mce_poll(struct file *file, poll_table *wait)
637 poll_wait(file, &mce_wait, wait);
638 if (rcu_dereference(mcelog.next))
639 return POLLIN | POLLRDNORM;
643 static long mce_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
645 int __user *p = (int __user *)arg;
647 if (!capable(CAP_SYS_ADMIN))
650 case MCE_GET_RECORD_LEN:
651 return put_user(sizeof(struct mce), p);
652 case MCE_GET_LOG_LEN:
653 return put_user(MCE_LOG_LEN, p);
654 case MCE_GETCLEAR_FLAGS: {
658 flags = mcelog.flags;
659 } while (cmpxchg(&mcelog.flags, flags, 0) != flags);
660 return put_user(flags, p);
667 static const struct file_operations mce_chrdev_ops = {
669 .release = mce_release,
672 .unlocked_ioctl = mce_ioctl,
675 static struct miscdevice mce_log_device = {
681 static unsigned long old_cr4 __initdata;
683 void __init stop_mce(void)
685 old_cr4 = read_cr4();
686 clear_in_cr4(X86_CR4_MCE);
689 void __init restart_mce(void)
691 if (old_cr4 & X86_CR4_MCE)
692 set_in_cr4(X86_CR4_MCE);
696 * Old style boot options parsing. Only for compatibility.
698 static int __init mcheck_disable(char *str)
704 /* mce=off disables machine check. Note you can re-enable it later
706 mce=TOLERANCELEVEL (number, see above)
707 mce=bootlog Log MCEs from before booting. Disabled by default on AMD.
708 mce=nobootlog Don't log MCEs from before booting. */
709 static int __init mcheck_enable(char *str)
711 if (!strcmp(str, "off"))
713 else if (!strcmp(str, "bootlog") || !strcmp(str,"nobootlog"))
714 mce_bootlog = str[0] == 'b';
715 else if (isdigit(str[0]))
716 get_option(&str, &tolerant);
718 printk("mce= argument %s ignored. Please use /sys", str);
722 __setup("nomce", mcheck_disable);
723 __setup("mce=", mcheck_enable);
729 /* On resume clear all MCE state. Don't want to see leftovers from the BIOS.
730 Only one CPU is active at this time, the others get readded later using
732 static int mce_resume(struct sys_device *dev)
738 /* Reinit MCEs after user configuration changes */
739 static void mce_restart(void)
742 cancel_delayed_work(&mcheck_work);
743 /* Timer race is harmless here */
744 on_each_cpu(mce_init, NULL, 1, 1);
745 next_interval = check_interval * HZ;
747 schedule_delayed_work(&mcheck_work,
748 round_jiffies_relative(next_interval));
751 static struct sysdev_class mce_sysclass = {
752 .resume = mce_resume,
753 .name = "machinecheck",
756 DEFINE_PER_CPU(struct sys_device, device_mce);
758 /* Why are there no generic functions for this? */
759 #define ACCESSOR(name, var, start) \
760 static ssize_t show_ ## name(struct sys_device *s, char *buf) { \
761 return sprintf(buf, "%lx\n", (unsigned long)var); \
763 static ssize_t set_ ## name(struct sys_device *s,const char *buf,size_t siz) { \
765 unsigned long new = simple_strtoul(buf, &end, 0); \
766 if (end == buf) return -EINVAL; \
771 static SYSDEV_ATTR(name, 0644, show_ ## name, set_ ## name);
773 /* TBD should generate these dynamically based on number of available banks */
774 ACCESSOR(bank0ctl,bank[0],mce_restart())
775 ACCESSOR(bank1ctl,bank[1],mce_restart())
776 ACCESSOR(bank2ctl,bank[2],mce_restart())
777 ACCESSOR(bank3ctl,bank[3],mce_restart())
778 ACCESSOR(bank4ctl,bank[4],mce_restart())
779 ACCESSOR(bank5ctl,bank[5],mce_restart())
781 static ssize_t show_trigger(struct sys_device *s, char *buf)
783 strcpy(buf, trigger);
785 return strlen(trigger) + 1;
788 static ssize_t set_trigger(struct sys_device *s,const char *buf,size_t siz)
792 strncpy(trigger, buf, sizeof(trigger));
793 trigger[sizeof(trigger)-1] = 0;
794 len = strlen(trigger);
795 p = strchr(trigger, '\n');
800 static SYSDEV_ATTR(trigger, 0644, show_trigger, set_trigger);
801 ACCESSOR(tolerant,tolerant,)
802 ACCESSOR(check_interval,check_interval,mce_restart())
803 static struct sysdev_attribute *mce_attributes[] = {
804 &attr_bank0ctl, &attr_bank1ctl, &attr_bank2ctl,
805 &attr_bank3ctl, &attr_bank4ctl, &attr_bank5ctl,
806 &attr_tolerant, &attr_check_interval, &attr_trigger,
810 static cpumask_t mce_device_initialized = CPU_MASK_NONE;
812 /* Per cpu sysdev init. All of the cpus still share the same ctl bank */
813 static __cpuinit int mce_create_device(unsigned int cpu)
818 if (!mce_available(&boot_cpu_data))
821 memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject));
822 per_cpu(device_mce,cpu).id = cpu;
823 per_cpu(device_mce,cpu).cls = &mce_sysclass;
825 err = sysdev_register(&per_cpu(device_mce,cpu));
829 for (i = 0; mce_attributes[i]; i++) {
830 err = sysdev_create_file(&per_cpu(device_mce,cpu),
835 cpu_set(cpu, mce_device_initialized);
840 sysdev_remove_file(&per_cpu(device_mce,cpu),
843 sysdev_unregister(&per_cpu(device_mce,cpu));
848 static void mce_remove_device(unsigned int cpu)
852 if (!cpu_isset(cpu, mce_device_initialized))
855 for (i = 0; mce_attributes[i]; i++)
856 sysdev_remove_file(&per_cpu(device_mce,cpu),
858 sysdev_unregister(&per_cpu(device_mce,cpu));
859 cpu_clear(cpu, mce_device_initialized);
862 /* Get notified when a cpu comes on/off. Be hotplug friendly. */
863 static int __cpuinit mce_cpu_callback(struct notifier_block *nfb,
864 unsigned long action, void *hcpu)
866 unsigned int cpu = (unsigned long)hcpu;
870 case CPU_ONLINE_FROZEN:
871 mce_create_device(cpu);
874 case CPU_DEAD_FROZEN:
875 mce_remove_device(cpu);
881 static struct notifier_block mce_cpu_notifier __cpuinitdata = {
882 .notifier_call = mce_cpu_callback,
885 static __init int mce_init_device(void)
890 if (!mce_available(&boot_cpu_data))
892 err = sysdev_class_register(&mce_sysclass);
896 for_each_online_cpu(i) {
897 err = mce_create_device(i);
902 register_hotcpu_notifier(&mce_cpu_notifier);
903 misc_register(&mce_log_device);
907 device_initcall(mce_init_device);