x86_64: prepare shared kernel/mce.c
authorThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:14:53 +0000 (11:14 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:14:53 +0000 (11:14 +0200)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86_64/kernel/Makefile
arch/x86_64/kernel/mce.c [deleted file]
arch/x86_64/kernel/mce_64.c [new file with mode: 0644]

index fc8d1319e911165cd3a7b824bd9d252893f13b45..b0a29b510427a151074ee2eae95b0ccae21dc311 100644 (file)
@@ -12,7 +12,7 @@ obj-y := process.o signal_64.o entry.o traps_64.o irq.o \
                perfctr-watchdog.o
 
 obj-$(CONFIG_STACKTRACE)       += stacktrace.o
-obj-$(CONFIG_X86_MCE)          += mce.o therm_throt.o
+obj-$(CONFIG_X86_MCE)          += mce_64.o therm_throt.o
 obj-$(CONFIG_X86_MCE_INTEL)    += mce_intel_64.o
 obj-$(CONFIG_X86_MCE_AMD)      += mce_amd_64.o
 obj-$(CONFIG_MTRR)             += ../../i386/kernel/cpu/mtrr/
diff --git a/arch/x86_64/kernel/mce.c b/arch/x86_64/kernel/mce.c
deleted file mode 100644 (file)
index a66d607..0000000
+++ /dev/null
@@ -1,875 +0,0 @@
-/*
- * 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, &notify_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(&current_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,
-                               (int)round_jiffies_relative(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, &notify_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,
-                                     round_jiffies_relative(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,
-};
-
-static unsigned long old_cr4 __initdata;
-
-void __init stop_mce(void)
-{
-       old_cr4 = read_cr4();
-       clear_in_cr4(X86_CR4_MCE);
-}
-
-void __init restart_mce(void)
-{
-       if (old_cr4 & X86_CR4_MCE)
-               set_in_cr4(X86_CR4_MCE);
-}
-
-/* 
- * 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,
-                                     round_jiffies_relative(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);
diff --git a/arch/x86_64/kernel/mce_64.c b/arch/x86_64/kernel/mce_64.c
new file mode 100644 (file)
index 0000000..a66d607
--- /dev/null
@@ -0,0 +1,875 @@
+/*
+ * 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, &notify_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(&current_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,
+                               (int)round_jiffies_relative(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, &notify_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,
+                                     round_jiffies_relative(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,
+};
+
+static unsigned long old_cr4 __initdata;
+
+void __init stop_mce(void)
+{
+       old_cr4 = read_cr4();
+       clear_in_cr4(X86_CR4_MCE);
+}
+
+void __init restart_mce(void)
+{
+       if (old_cr4 & X86_CR4_MCE)
+               set_in_cr4(X86_CR4_MCE);
+}
+
+/* 
+ * 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,
+                                     round_jiffies_relative(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);