/*
* Machine check handler.
* K8 parts Copyright 2002,2003 Andi Kleen, SuSE Labs.
* Rest from unknown author(s).
* 2004 Andi Kleen. Rewrote most of it.
*/
#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
#include <linux/sysdev.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/percpu.h>
#include <linux/poll.h>
#include <linux/thread_info.h>
#include <linux/ctype.h>
#include <linux/kmod.h>
#include <linux/kdebug.h>
#include <asm/processor.h>
#include <asm/msr.h>
#include <asm/mce.h>
#include <asm/uaccess.h>
#include <asm/smp.h>
#include <asm/idle.h>
#define MISC_MCELOG_MINOR 227
#define NR_BANKS 6
atomic_t mce_entry;
static int mce_dont_init;
/*
* Tolerant levels:
* 0: always panic on uncorrected errors, log corrected errors
* 1: panic or SIGBUS on uncorrected errors, log corrected errors
* 2: SIGBUS or log uncorrected errors (if possible), log corrected errors
* 3: never panic or SIGBUS, log all errors (for testing only)
*/
static int tolerant = 1;
static int banks;
static unsigned long bank[NR_BANKS] = { [0 ... NR_BANKS-1] = ~0UL };
static unsigned long notify_user;
static int rip_msr;
static int mce_bootlog = 1;
static atomic_t mce_events;
static char trigger[128];
static char *trigger_argv[2] = { trigger, NULL };
static DECLARE_WAIT_QUEUE_HEAD(mce_wait);
/*
* Lockless MCE logging infrastructure.
* This avoids deadlocks on printk locks without having to break locks. Also
* separate MCEs from kernel messages to avoid bogus bug reports.
*/
struct mce_log mcelog = {
MCE_LOG_SIGNATURE,
MCE_LOG_LEN,
};
void mce_log(struct mce *mce)
{
unsigned next, entry;
atomic_inc(&mce_events);
mce->finished = 0;
wmb();
for (;;) {
entry = rcu_dereference(mcelog.next);
/* The rmb forces the compiler to reload next in each
iteration */
rmb();
for (;;) {
/* When the buffer fills up discard new entries. Assume
that the earlier errors are the more interesting. */
if (entry >= MCE_LOG_LEN) {
set_bit(MCE_OVERFLOW, &mcelog.flags);
return;
}
/* Old left over entry. Skip. */
if (mcelog.entry[entry].finished) {
entry++;
continue;
}
break;
}
smp_rmb();
next = entry + 1;
if (cmpxchg(&mcelog.next, entry, next) == entry)
break;
}
memcpy(mcelog.entry + entry, mce, sizeof(struct mce));
wmb();
mcelog.entry[entry].finished = 1;
wmb();
set_bit(0, ¬ify_user);
}
static void print_mce(struct mce *m)
{
printk(KERN_EMERG "\n"
KERN_EMERG "HARDWARE ERROR\n"
KERN_EMERG
"CPU %d: Machine Check Exception: %16Lx Bank %d: %016Lx\n",
m->cpu, m->mcgstatus, m->bank, m->status);
if (m->rip) {
printk(KERN_EMERG
"RIP%s %02x:<%016Lx> ",
!(m->mcgstatus & MCG_STATUS_EIPV) ? " !INEXACT!" : "",
m->cs, m->rip);
if (m->cs == __KERNEL_CS)
print_symbol("{%s}", m->rip);
printk("\n");
}
printk(KERN_EMERG "TSC %Lx ", m->tsc);
if (m->addr)
printk("ADDR %Lx ", m->addr);
if (m->misc)
printk("MISC %Lx ", m->misc);
printk("\n");
printk(KERN_EMERG "This is not a software problem!\n");
printk(KERN_EMERG
"Run through mcelog --ascii to decode and contact your hardware vendor\n");
}
static void mce_panic(char *msg, struct mce *backup, unsigned long start)
{
int i;
oops_begin();
for (i = 0; i < MCE_LOG_LEN; i++) {
unsigned long tsc = mcelog.entry[i].tsc;
if (time_before(tsc, start))
continue;
print_mce(&mcelog.entry[i]);
if (backup && mcelog.entry[i].tsc == backup->tsc)
backup = NULL;
}
if (backup)
print_mce(backup);
panic(msg);
}
static int mce_available(struct cpuinfo_x86 *c)
{
return cpu_has(c, X86_FEATURE_MCE) && cpu_has(c, X86_FEATURE_MCA);
}
static inline void mce_get_rip(struct mce *m, struct pt_regs *regs)
{
if (regs && (m->mcgstatus & MCG_STATUS_RIPV)) {
m->rip = regs->rip;
m->cs = regs->cs;
} else {
m->rip = 0;
m->cs = 0;
}
if (rip_msr) {
/* Assume the RIP in the MSR is exact. Is this true? */
m->mcgstatus |= MCG_STATUS_EIPV;
rdmsrl(rip_msr, m->rip);
m->cs = 0;
}
}
/*
* The actual machine check handler
*/
void do_machine_check(struct pt_regs * regs, long error_code)
{
struct mce m, panicm;
u64 mcestart = 0;
int i;
int panicm_found = 0;
/*
* If no_way_out gets set, there is no safe way to recover from this
* MCE. If tolerant is cranked up, we'll try anyway.
*/
int no_way_out = 0;
/*
* If kill_it gets set, there might be a way to recover from this
* error.
*/
int kill_it = 0;
atomic_inc(&mce_entry);
if (regs)
notify_die(DIE_NMI, "machine check", regs, error_code, 18, SIGKILL);
if (!banks)
goto out2;
memset(&m, 0, sizeof(struct mce));
m.cpu = smp_processor_id();
rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
/* if the restart IP is not valid, we're done for */
if (!(m.mcgstatus & MCG_STATUS_RIPV))
no_way_out = 1;
rdtscll(mcestart);
barrier();
for (i = 0; i < banks; i++) {
if (!bank[i])
continue;
m.misc = 0;
m.addr = 0;
m.bank = i;
m.tsc = 0;
rdmsrl(MSR_IA32_MC0_STATUS + i*4, m.status);
if ((m.status & MCI_STATUS_VAL) == 0)
continue;
if (m.status & MCI_STATUS_EN) {
/* if PCC was set, there's no way out */
no_way_out |= !!(m.status & MCI_STATUS_PCC);
/*
* If this error was uncorrectable and there was
* an overflow, we're in trouble. If no overflow,
* we might get away with just killing a task.
*/
if (m.status & MCI_STATUS_UC) {
if (tolerant < 1 || m.status & MCI_STATUS_OVER)
no_way_out = 1;
kill_it = 1;
}
}
if (m.status & MCI_STATUS_MISCV)
rdmsrl(MSR_IA32_MC0_MISC + i*4, m.misc);
if (m.status & MCI_STATUS_ADDRV)
rdmsrl(MSR_IA32_MC0_ADDR + i*4, m.addr);
mce_get_rip(&m, regs);
if (error_code >= 0)
rdtscll(m.tsc);
if (error_code != -2)
mce_log(&m);
/* Did this bank cause the exception? */
/* Assume that the bank with uncorrectable errors did it,
and that there is only a single one. */
if ((m.status & MCI_STATUS_UC) && (m.status & MCI_STATUS_EN)) {
panicm = m;
panicm_found = 1;
}
add_taint(TAINT_MACHINE_CHECK);
}
/* Never do anything final in the polling timer */
if (!regs)
goto out;
/* If we didn't find an uncorrectable error, pick
the last one (shouldn't happen, just being safe). */
if (!panicm_found)
panicm = m;
/*
* If we have decided that we just CAN'T continue, and the user
* has not set tolerant to an insane level, give up and die.
*/
if (no_way_out && tolerant < 3)
mce_panic("Machine check", &panicm, mcestart);
/*
* If the error seems to be unrecoverable, something should be
* done. Try to kill as little as possible. If we can kill just
* one task, do that. If the user has set the tolerance very
* high, don't try to do anything at all.
*/
if (kill_it && tolerant < 3) {
int user_space = 0;
/*
* If the EIPV bit is set, it means the saved IP is the
* instruction which caused the MCE.
*/
if (m.mcgstatus & MCG_STATUS_EIPV)
user_space = panicm.rip && (panicm.cs & 3);
/*
* If we know that the error was in user space, send a
* SIGBUS. Otherwise, panic if tolerance is low.
*
* do_exit() takes an awful lot of locks and has a slight
* risk of deadlocking.
*/
if (user_space) {
do_exit(SIGBUS);
} else if (panic_on_oops || tolerant < 2) {
mce_panic("Uncorrected machine check",
&panicm, mcestart);
}
}
/* notify userspace ASAP */
set_thread_flag(TIF_MCE_NOTIFY);
out:
/* the last thing we do is clear state */
for (i = 0; i < banks; i++)
wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
wrmsrl(MSR_IA32_MCG_STATUS, 0);
out2:
atomic_dec(&mce_entry);
}
#ifdef CONFIG_X86_MCE_INTEL
/***
* mce_log_therm_throt_event - Logs the thermal throttling event to mcelog
* @cpu: The CPU on which the event occured.
* @status: Event status information
*
* This function should be called by the thermal interrupt after the
* event has been processed and the decision was made to log the event
* further.
*
* The status parameter will be saved to the 'status' field of 'struct mce'
* and historically has been the register value of the
* MSR_IA32_THERMAL_STATUS (Intel) msr.
*/
void mce_log_therm_throt_event(unsigned int cpu, __u64 status)
{
struct mce m;
memset(&m, 0, sizeof(m));
m.cpu = cpu;
m.bank = MCE_THERMAL_BANK;
m.status = status;
rdtscll(m.tsc);
mce_log(&m);
}
#endif /* CONFIG_X86_MCE_INTEL */
/*
* Periodic polling timer for "silent" machine check errors. If the
* poller finds an MCE, poll 2x faster. When the poller finds no more
* errors, poll 2x slower (up to check_interval seconds).
*/
static int check_interval = 5 * 60; /* 5 minutes */
static int next_interval; /* in jiffies */
static void mcheck_timer(struct work_struct *work);
static DECLARE_DELAYED_WORK(mcheck_work, mcheck_timer);
static void mcheck_check_cpu(void *info)
{
if (mce_available(¤t_cpu_data))
do_machine_check(NULL, 0);
}
static void mcheck_timer(struct work_struct *work)
{
on_each_cpu(mcheck_check_cpu, NULL, 1, 1);
/*
* Alert userspace if needed. If we logged an MCE, reduce the
* polling interval, otherwise increase the polling interval.
*/
if (mce_notify_user()) {
next_interval = max(next_interval/2, HZ/100);
} else {
next_interval = min(next_interval*2, check_interval*HZ);
}
schedule_delayed_work(&mcheck_work, next_interval);
}
/*
* This is only called from process context. This is where we do
* anything we need to alert userspace about new MCEs. This is called
* directly from the poller and also from entry.S and idle, thanks to
* TIF_MCE_NOTIFY.
*/
int mce_notify_user(void)
{
clear_thread_flag(TIF_MCE_NOTIFY);
if (test_and_clear_bit(0, ¬ify_user)) {
static unsigned long last_print;
unsigned long now = jiffies;
wake_up_interruptible(&mce_wait);
if (trigger[0])
call_usermodehelper(trigger, trigger_argv, NULL,
UMH_NO_WAIT);
if (time_after_eq(now, last_print + (check_interval*HZ))) {
last_print = now;
printk(KERN_INFO "Machine check events logged\n");
}
return 1;
}
return 0;
}
/* see if the idle task needs to notify userspace */
static int
mce_idle_callback(struct notifier_block *nfb, unsigned long action, void *junk)
{
/* IDLE_END should be safe - interrupts are back on */
if (action == IDLE_END && test_thread_flag(TIF_MCE_NOTIFY))
mce_notify_user();
return NOTIFY_OK;
}
static struct notifier_block mce_idle_notifier = {
.notifier_call = mce_idle_callback,
};
static __init int periodic_mcheck_init(void)
{
next_interval = check_interval * HZ;
if (next_interval)
schedule_delayed_work(&mcheck_work, next_interval);
idle_notifier_register(&mce_idle_notifier);
return 0;
}
__initcall(periodic_mcheck_init);
/*
* Initialize Machine Checks for a CPU.
*/
static void mce_init(void *dummy)
{
u64 cap;
int i;
rdmsrl(MSR_IA32_MCG_CAP, cap);
banks = cap & 0xff;
if (banks > NR_BANKS) {
printk(KERN_INFO "MCE: warning: using only %d banks\n", banks);
banks = NR_BANKS;
}
/* Use accurate RIP reporting if available. */
if ((cap & (1<<9)) && ((cap >> 16) & 0xff) >= 9)
rip_msr = MSR_IA32_MCG_EIP;
/* Log the machine checks left over from the previous reset.
This also clears all registers */
do_machine_check(NULL, mce_bootlog ? -1 : -2);
set_in_cr4(X86_CR4_MCE);
if (cap & MCG_CTL_P)
wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff);
for (i = 0; i < banks; i++) {
wrmsrl(MSR_IA32_MC0_CTL+4*i, bank[i]);
wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
}
}
/* Add per CPU specific workarounds here */
static void __cpuinit mce_cpu_quirks(struct cpuinfo_x86 *c)
{
/* This should be disabled by the BIOS, but isn't always */
if (c->x86_vendor == X86_VENDOR_AMD && c->x86 == 15) {
/* disable GART TBL walk error reporting, which trips off
incorrectly with the IOMMU & 3ware & Cerberus. */
clear_bit(10, &bank[4]);
/* Lots of broken BIOS around that don't clear them
by default and leave crap in there. Don't log. */
mce_bootlog = 0;
}
}
static void __cpuinit mce_cpu_features(struct cpuinfo_x86 *c)
{
switch (c->x86_vendor) {
case X86_VENDOR_INTEL:
mce_intel_feature_init(c);
break;
case X86_VENDOR_AMD:
mce_amd_feature_init(c);
break;
default:
break;
}
}
/*
* Called for each booted CPU to set up machine checks.
* Must be called with preempt off.
*/
void __cpuinit mcheck_init(struct cpuinfo_x86 *c)
{
static cpumask_t mce_cpus = CPU_MASK_NONE;
mce_cpu_quirks(c);
if (mce_dont_init ||
cpu_test_and_set(smp_processor_id(), mce_cpus) ||
!mce_available(c))
return;
mce_init(NULL);
mce_cpu_features(c);
}
/*
* Character device to read and clear the MCE log.
*/
static DEFINE_SPINLOCK(mce_state_lock);
static int open_count; /* #times opened */
static int open_exclu; /* already open exclusive? */
static int mce_open(struct inode *inode, struct file *file)
{
spin_lock(&mce_state_lock);
if (open_exclu || (open_count && (file->f_flags & O_EXCL))) {
spin_unlock(&mce_state_lock);
return -EBUSY;
}
if (file->f_flags & O_EXCL)
open_exclu = 1;
open_count++;
spin_unlock(&mce_state_lock);
return nonseekable_open(inode, file);
}
static int mce_release(struct inode *inode, struct file *file)
{
spin_lock(&mce_state_lock);
open_count--;
open_exclu = 0;
spin_unlock(&mce_state_lock);
return 0;
}
static void collect_tscs(void *data)
{
unsigned long *cpu_tsc = (unsigned long *)data;
rdtscll(cpu_tsc[smp_processor_id()]);
}
static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize, loff_t *off)
{
unsigned long *cpu_tsc;
static DECLARE_MUTEX(mce_read_sem);
unsigned next;
char __user *buf = ubuf;
int i, err;
cpu_tsc = kmalloc(NR_CPUS * sizeof(long), GFP_KERNEL);
if (!cpu_tsc)
return -ENOMEM;
down(&mce_read_sem);
next = rcu_dereference(mcelog.next);
/* Only supports full reads right now */
if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce)) {
up(&mce_read_sem);
kfree(cpu_tsc);
return -EINVAL;
}
err = 0;
for (i = 0; i < next; i++) {
unsigned long start = jiffies;
while (!mcelog.entry[i].finished) {
if (time_after_eq(jiffies, start + 2)) {
memset(mcelog.entry + i,0, sizeof(struct mce));
goto timeout;
}
cpu_relax();
}
smp_rmb();
err |= copy_to_user(buf, mcelog.entry + i, sizeof(struct mce));
buf += sizeof(struct mce);
timeout:
;
}
memset(mcelog.entry, 0, next * sizeof(struct mce));
mcelog.next = 0;
synchronize_sched();
/* Collect entries that were still getting written before the synchronize. */
on_each_cpu(collect_tscs, cpu_tsc, 1, 1);
for (i = next; i < MCE_LOG_LEN; i++) {
if (mcelog.entry[i].finished &&
mcelog.entry[i].tsc < cpu_tsc[mcelog.entry[i].cpu]) {
err |= copy_to_user(buf, mcelog.entry+i, sizeof(struct mce));
smp_rmb();
buf += sizeof(struct mce);
memset(&mcelog.entry[i], 0, sizeof(struct mce));
}
}
up(&mce_read_sem);
kfree(cpu_tsc);
return err ? -EFAULT : buf - ubuf;
}
static unsigned int mce_poll(struct file *file, poll_table *wait)
{
poll_wait(file, &mce_wait, wait);
if (rcu_dereference(mcelog.next))
return POLLIN | POLLRDNORM;
return 0;
}
static int mce_ioctl(struct inode *i, struct file *f,unsigned int cmd, unsigned long arg)
{
int __user *p = (int __user *)arg;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
switch (cmd) {
case MCE_GET_RECORD_LEN:
return put_user(sizeof(struct mce), p);
case MCE_GET_LOG_LEN:
return put_user(MCE_LOG_LEN, p);
case MCE_GETCLEAR_FLAGS: {
unsigned flags;
do {
flags = mcelog.flags;
} while (cmpxchg(&mcelog.flags, flags, 0) != flags);
return put_user(flags, p);
}
default:
return -ENOTTY;
}
}
static const struct file_operations mce_chrdev_ops = {
.open = mce_open,
.release = mce_release,
.read = mce_read,
.poll = mce_poll,
.ioctl = mce_ioctl,
};
static struct miscdevice mce_log_device = {
MISC_MCELOG_MINOR,
"mcelog",
&mce_chrdev_ops,
};
/*
* Old style boot options parsing. Only for compatibility.
*/
static int __init mcheck_disable(char *str)
{
mce_dont_init = 1;
return 1;
}
/* mce=off disables machine check. Note you can reenable it later
using sysfs.
mce=TOLERANCELEVEL (number, see above)
mce=bootlog Log MCEs from before booting. Disabled by default on AMD.
mce=nobootlog Don't log MCEs from before booting. */
static int __init mcheck_enable(char *str)
{
if (*str == '=')
str++;
if (!strcmp(str, "off"))
mce_dont_init = 1;
else if (!strcmp(str, "bootlog") || !strcmp(str,"nobootlog"))
mce_bootlog = str[0] == 'b';
else if (isdigit(str[0]))
get_option(&str, &tolerant);
else
printk("mce= argument %s ignored. Please use /sys", str);
return 1;
}
__setup("nomce", mcheck_disable);
__setup("mce", mcheck_enable);
/*
* Sysfs support
*/
/* On resume clear all MCE state. Don't want to see leftovers from the BIOS.
Only one CPU is active at this time, the others get readded later using
CPU hotplug. */
static int mce_resume(struct sys_device *dev)
{
mce_init(NULL);
return 0;
}
/* Reinit MCEs after user configuration changes */
static void mce_restart(void)
{
if (next_interval)
cancel_delayed_work(&mcheck_work);
/* Timer race is harmless here */
on_each_cpu(mce_init, NULL, 1, 1);
next_interval = check_interval * HZ;
if (next_interval)
schedule_delayed_work(&mcheck_work, next_interval);
}
static struct sysdev_class mce_sysclass = {
.resume = mce_resume,
set_kset_name("machinecheck"),
};
DEFINE_PER_CPU(struct sys_device, device_mce);
/* Why are there no generic functions for this? */
#define ACCESSOR(name, var, start) \
static ssize_t show_ ## name(struct sys_device *s, char *buf) { \
return sprintf(buf, "%lx\n", (unsigned long)var); \
} \
static ssize_t set_ ## name(struct sys_device *s,const char *buf,size_t siz) { \
char *end; \
unsigned long new = simple_strtoul(buf, &end, 0); \
if (end == buf) return -EINVAL; \
var = new; \
start; \
return end-buf; \
} \
static SYSDEV_ATTR(name, 0644, show_ ## name, set_ ## name);
/* TBD should generate these dynamically based on number of available banks */
ACCESSOR(bank0ctl,bank[0],mce_restart())
ACCESSOR(bank1ctl,bank[1],mce_restart())
ACCESSOR(bank2ctl,bank[2],mce_restart())
ACCESSOR(bank3ctl,bank[3],mce_restart())
ACCESSOR(bank4ctl,bank[4],mce_restart())
ACCESSOR(bank5ctl,bank[5],mce_restart())
static ssize_t show_trigger(struct sys_device *s, char *buf)
{
strcpy(buf, trigger);
strcat(buf, "\n");
return strlen(trigger) + 1;
}
static ssize_t set_trigger(struct sys_device *s,const char *buf,size_t siz)
{
char *p;
int len;
strncpy(trigger, buf, sizeof(trigger));
trigger[sizeof(trigger)-1] = 0;
len = strlen(trigger);
p = strchr(trigger, '\n');
if (*p) *p = 0;
return len;
}
static SYSDEV_ATTR(trigger, 0644, show_trigger, set_trigger);
ACCESSOR(tolerant,tolerant,)
ACCESSOR(check_interval,check_interval,mce_restart())
static struct sysdev_attribute *mce_attributes[] = {
&attr_bank0ctl, &attr_bank1ctl, &attr_bank2ctl,
&attr_bank3ctl, &attr_bank4ctl, &attr_bank5ctl,
&attr_tolerant, &attr_check_interval, &attr_trigger,
NULL
};
/* Per cpu sysdev init. All of the cpus still share the same ctl bank */
static __cpuinit int mce_create_device(unsigned int cpu)
{
int err;
int i;
if (!mce_available(&cpu_data[cpu]))
return -EIO;
per_cpu(device_mce,cpu).id = cpu;
per_cpu(device_mce,cpu).cls = &mce_sysclass;
err = sysdev_register(&per_cpu(device_mce,cpu));
if (!err) {
for (i = 0; mce_attributes[i]; i++)
sysdev_create_file(&per_cpu(device_mce,cpu),
mce_attributes[i]);
}
return err;
}
static void mce_remove_device(unsigned int cpu)
{
int i;
for (i = 0; mce_attributes[i]; i++)
sysdev_remove_file(&per_cpu(device_mce,cpu),
mce_attributes[i]);
sysdev_unregister(&per_cpu(device_mce,cpu));
memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject));
}
/* Get notified when a cpu comes on/off. Be hotplug friendly. */
static int
mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
switch (action) {
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
mce_create_device(cpu);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
mce_remove_device(cpu);
break;
}
return NOTIFY_OK;
}
static struct notifier_block mce_cpu_notifier = {
.notifier_call = mce_cpu_callback,
};
static __init int mce_init_device(void)
{
int err;
int i = 0;
if (!mce_available(&boot_cpu_data))
return -EIO;
err = sysdev_class_register(&mce_sysclass);
for_each_online_cpu(i) {
mce_create_device(i);
}
register_hotcpu_notifier(&mce_cpu_notifier);
misc_register(&mce_log_device);
return err;
}
device_initcall(mce_init_device);
