Linux-2.6.12-rc2

[mirror_ubuntu-artful-kernel.git] / arch / x86_64 / kernel / mce.c

/*
 * 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;

/*
 * 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);
}

/* 
 * 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);

                if (regs && (m.mcgstatus & MCG_STATUS_RIPV)) {
                        m.rip = regs->rip;
                        m.cs = regs->cs;
                } else {
                        m.rip = 0;
                        m.cs = 0;
                }

                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(&current_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; 
        }

        /* 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[NR_CPUS];
        static DECLARE_MUTEX(mce_read_sem);
        unsigned next;
        char __user *buf = ubuf;
        int i, err;

        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);
                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);
        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);