/*
* 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 <asm/processor.h>
#include <asm/msr.h>
#include <asm/mce.h>
#include <asm/kdebug.h>
#include <asm/uaccess.h>
#define MISC_MCELOG_MINOR 227
#define NR_BANKS 5
static int mce_dont_init;
/* 0: always panic, 1: panic if deadlock possible, 2: try to avoid panic,
3: never panic or exit (for testing only) */
static int tolerant = 1;
static int banks;
static unsigned long bank[NR_BANKS] = { [0 ... NR_BANKS-1] = ~0UL };
static unsigned long console_logged;
static int notify_user;
static int rip_msr;
/*
* 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;
mce->finished = 0;
smp_wmb();
for (;;) {
entry = rcu_dereference(mcelog.next);
/* 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)
continue;
smp_rmb();
next = entry + 1;
if (cmpxchg(&mcelog.next, entry, next) == entry)
break;
}
memcpy(mcelog.entry + entry, mce, sizeof(struct mce));
smp_wmb();
mcelog.entry[entry].finished = 1;
smp_wmb();
if (!test_and_set_bit(0, &console_logged))
notify_user = 1;
}
static void print_mce(struct mce *m)
{
printk(KERN_EMERG "\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");
}
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);
if (tolerant >= 3)
printk("Fake panic: %s\n", msg);
else
panic(msg);
}
static int mce_available(struct cpuinfo_x86 *c)
{
return test_bit(X86_FEATURE_MCE, &c->x86_capability) &&
test_bit(X86_FEATURE_MCA, &c->x86_capability);
}
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;
int nowayout = (tolerant < 1);
int kill_it = 0;
u64 mcestart = 0;
int i;
int panicm_found = 0;
if (regs)
notify_die(DIE_NMI, "machine check", regs, error_code, 255, SIGKILL);
if (!banks)
return;
memset(&m, 0, sizeof(struct mce));
m.cpu = hard_smp_processor_id();
rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
if (!(m.mcgstatus & MCG_STATUS_RIPV))
kill_it = 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) {
/* In theory _OVER could be a nowayout too, but
assume any overflowed errors were no fatal. */
nowayout |= !!(m.status & MCI_STATUS_PCC);
kill_it |= !!(m.status & MCI_STATUS_UC);
}
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 != -1)
rdtscll(m.tsc);
wrmsrl(MSR_IA32_MC0_STATUS + i*4, 0);
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;
}
tainted |= 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 (nowayout)
mce_panic("Machine check", &panicm, mcestart);
if (kill_it) {
int user_space = 0;
if (m.mcgstatus & MCG_STATUS_RIPV)
user_space = panicm.rip && (panicm.cs & 3);
/* When the machine was in user space and the CPU didn't get
confused it's normally not necessary to panic, unless you
are paranoid (tolerant == 0)
RED-PEN could be more tolerant for MCEs in idle,
but most likely they occur at boot anyways, where
it is best to just halt the machine. */
if ((!user_space && (panic_on_oops || tolerant < 2)) ||
(unsigned)current->pid <= 1)
mce_panic("Uncorrected machine check", &panicm, mcestart);
/* do_exit takes an awful lot of locks and has as
slight risk of deadlocking. If you don't want that
don't set tolerant >= 2 */
if (tolerant < 3)
do_exit(SIGBUS);
}
out:
/* Last thing done in the machine check exception to clear state. */
wrmsrl(MSR_IA32_MCG_STATUS, 0);
}
/*
* Periodic polling timer for "silent" machine check errors.
*/
static int check_interval = 5 * 60; /* 5 minutes */
static void mcheck_timer(void *data);
static DECLARE_WORK(mcheck_work, mcheck_timer, NULL);
static void mcheck_check_cpu(void *info)
{
if (mce_available(¤t_cpu_data))
do_machine_check(NULL, 0);
}
static void mcheck_timer(void *data)
{
on_each_cpu(mcheck_check_cpu, NULL, 1, 1);
schedule_delayed_work(&mcheck_work, check_interval * HZ);
/*
* It's ok to read stale data here for notify_user and
* console_logged as we'll simply get the updated versions
* on the next mcheck_timer execution and atomic operations
* on console_logged act as synchronization for notify_user
* writes.
*/
if (notify_user && console_logged) {
notify_user = 0;
clear_bit(0, &console_logged);
printk(KERN_INFO "Machine check events logged\n");
}
}
static __init int periodic_mcheck_init(void)
{
if (check_interval)
schedule_delayed_work(&mcheck_work, check_interval*HZ);
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, -1);
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 __init 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]);
}
}
static void __init mce_cpu_features(struct cpuinfo_x86 *c)
{
switch (c->x86_vendor) {
case X86_VENDOR_INTEL:
mce_intel_feature_init(c);
break;
default:
break;
}
}
/*
* Called for each booted CPU to set up machine checks.
* Must be called with preempt off.
*/
void __init mcheck_init(struct cpuinfo_x86 *c)
{
static cpumask_t mce_cpus __initdata = 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 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++) {
if (!mcelog.entry[i].finished)
continue;
smp_rmb();
err |= copy_to_user(buf, mcelog.entry + i, sizeof(struct mce));
buf += sizeof(struct mce);
}
memset(mcelog.entry, 0, next * sizeof(struct mce));
mcelog.next = 0;
synchronize_kernel();
/* 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 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 struct file_operations mce_chrdev_ops = {
.read = mce_read,
.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 0;
}
/* mce=off disables machine check. Note you can reenable it later
using sysfs */
static int __init mcheck_enable(char *str)
{
if (!strcmp(str, "off"))
mce_dont_init = 1;
else
printk("mce= argument %s ignored. Please use /sys", str);
return 0;
}
__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. */
static int mce_resume(struct sys_device *dev)
{
on_each_cpu(mce_init, NULL, 1, 1);
return 0;
}
/* Reinit MCEs after user configuration changes */
static void mce_restart(void)
{
if (check_interval)
cancel_delayed_work(&mcheck_work);
/* Timer race is harmless here */
on_each_cpu(mce_init, NULL, 1, 1);
if (check_interval)
schedule_delayed_work(&mcheck_work, check_interval*HZ);
}
static struct sysdev_class mce_sysclass = {
.resume = mce_resume,
set_kset_name("machinecheck"),
};
static struct sys_device device_mce = {
.id = 0,
.cls = &mce_sysclass,
};
/* 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);
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(tolerant,tolerant,)
ACCESSOR(check_interval,check_interval,mce_restart())
static __init int mce_init_device(void)
{
int err;
if (!mce_available(&boot_cpu_data))
return -EIO;
err = sysdev_class_register(&mce_sysclass);
if (!err)
err = sysdev_register(&device_mce);
if (!err) {
/* could create per CPU objects, but it is not worth it. */
sysdev_create_file(&device_mce, &attr_bank0ctl);
sysdev_create_file(&device_mce, &attr_bank1ctl);
sysdev_create_file(&device_mce, &attr_bank2ctl);
sysdev_create_file(&device_mce, &attr_bank3ctl);
sysdev_create_file(&device_mce, &attr_bank4ctl);
sysdev_create_file(&device_mce, &attr_tolerant);
sysdev_create_file(&device_mce, &attr_check_interval);
}
misc_register(&mce_log_device);
return err;
}
device_initcall(mce_init_device);
