Merge branch 'linus' into x86/urgent

Merge reason: pull in latest to fix a bug in it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1964 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
new file mode 100644
index 00000000000..fabba15e455
--- /dev/null
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -0,0 +1,1964 @@
+/*
+ * Machine check handler.
+ *
+ * K8 parts Copyright 2002,2003 Andi Kleen, SuSE Labs.
+ * Rest from unknown author(s).
+ * 2004 Andi Kleen. Rewrote most of it.
+ * Copyright 2008 Intel Corporation
+ * Author: Andi Kleen
+ */
+#include <linux/thread_info.h>
+#include <linux/capability.h>
+#include <linux/miscdevice.h>
+#include <linux/interrupt.h>
+#include <linux/ratelimit.h>
+#include <linux/kallsyms.h>
+#include <linux/rcupdate.h>
+#include <linux/kobject.h>
+#include <linux/uaccess.h>
+#include <linux/kdebug.h>
+#include <linux/kernel.h>
+#include <linux/percpu.h>
+#include <linux/string.h>
+#include <linux/sysdev.h>
+#include <linux/delay.h>
+#include <linux/ctype.h>
+#include <linux/sched.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/kmod.h>
+#include <linux/poll.h>
+#include <linux/nmi.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+
+#include <asm/processor.h>
+#include <asm/hw_irq.h>
+#include <asm/apic.h>
+#include <asm/idle.h>
+#include <asm/ipi.h>
+#include <asm/mce.h>
+#include <asm/msr.h>
+
+#include "mce-internal.h"
+#include "mce.h"
+
+/* Handle unconfigured int18 (should never happen) */
+static void unexpected_machine_check(struct pt_regs *regs, long error_code)
+{
+	printk(KERN_ERR "CPU#%d: Unexpected int18 (Machine Check).\n",
+	       smp_processor_id());
+}
+
+/* Call the installed machine check handler for this CPU setup. */
+void (*machine_check_vector)(struct pt_regs *, long error_code) =
+						unexpected_machine_check;
+
+int				mce_disabled;
+
+#ifdef CONFIG_X86_NEW_MCE
+
+#define MISC_MCELOG_MINOR	227
+
+#define SPINUNIT 100	/* 100ns */
+
+atomic_t mce_entry;
+
+DEFINE_PER_CPU(unsigned, mce_exception_count);
+
+/*
+ * 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 u64			*bank;
+static unsigned long		notify_user;
+static int			rip_msr;
+static int			mce_bootlog = -1;
+static int			monarch_timeout = -1;
+static int			mce_panic_timeout;
+static int			mce_dont_log_ce;
+int				mce_cmci_disabled;
+int				mce_ignore_ce;
+int				mce_ser;
+
+static char			trigger[128];
+static char			*trigger_argv[2] = { trigger, NULL };
+
+static unsigned long		dont_init_banks;
+
+static DECLARE_WAIT_QUEUE_HEAD(mce_wait);
+static DEFINE_PER_CPU(struct mce, mces_seen);
+static int			cpu_missing;
+
+
+/* MCA banks polled by the period polling timer for corrected events */
+DEFINE_PER_CPU(mce_banks_t, mce_poll_banks) = {
+	[0 ... BITS_TO_LONGS(MAX_NR_BANKS)-1] = ~0UL
+};
+
+static inline int skip_bank_init(int i)
+{
+	return i < BITS_PER_LONG && test_bit(i, &dont_init_banks);
+}
+
+static DEFINE_PER_CPU(struct work_struct, mce_work);
+
+/* Do initial initialization of a struct mce */
+void mce_setup(struct mce *m)
+{
+	memset(m, 0, sizeof(struct mce));
+	m->cpu = m->extcpu = smp_processor_id();
+	rdtscll(m->tsc);
+	/* We hope get_seconds stays lockless */
+	m->time = get_seconds();
+	m->cpuvendor = boot_cpu_data.x86_vendor;
+	m->cpuid = cpuid_eax(1);
+#ifdef CONFIG_SMP
+	m->socketid = cpu_data(m->extcpu).phys_proc_id;
+#endif
+	m->apicid = cpu_data(m->extcpu).initial_apicid;
+	rdmsrl(MSR_IA32_MCG_CAP, m->mcgcap);
+}
+
+DEFINE_PER_CPU(struct mce, injectm);
+EXPORT_PER_CPU_SYMBOL_GPL(injectm);
+
+/*
+ * 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.
+ */
+
+static struct mce_log mcelog = {
+	.signature	= MCE_LOG_SIGNATURE,
+	.len		= MCE_LOG_LEN,
+	.recordlen	= sizeof(struct mce),
+};
+
+void mce_log(struct mce *mce)
+{
+	unsigned next, entry;
+
+	mce->finished = 0;
+	wmb();
+	for (;;) {
+		entry = rcu_dereference(mcelog.next);
+		for (;;) {
+			/*
+			 * When the buffer fills up discard new entries.
+			 * Assume that the earlier errors are the more
+			 * interesting ones:
+			 */
+			if (entry >= MCE_LOG_LEN) {
+				set_bit(MCE_OVERFLOW,
+					(unsigned long *)&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();
+
+	mce->finished = 1;
+	set_bit(0, &notify_user);
+}
+
+static void print_mce(struct mce *m)
+{
+	printk(KERN_EMERG
+	       "CPU %d: Machine Check Exception: %16Lx Bank %d: %016Lx\n",
+	       m->extcpu, m->mcgstatus, m->bank, m->status);
+	if (m->ip) {
+		printk(KERN_EMERG "RIP%s %02x:<%016Lx> ",
+		       !(m->mcgstatus & MCG_STATUS_EIPV) ? " !INEXACT!" : "",
+		       m->cs, m->ip);
+		if (m->cs == __KERNEL_CS)
+			print_symbol("{%s}", m->ip);
+		printk("\n");
+	}
+	printk(KERN_EMERG "TSC %llx ", m->tsc);
+	if (m->addr)
+		printk("ADDR %llx ", m->addr);
+	if (m->misc)
+		printk("MISC %llx ", m->misc);
+	printk("\n");
+	printk(KERN_EMERG "PROCESSOR %u:%x TIME %llu SOCKET %u APIC %x\n",
+			m->cpuvendor, m->cpuid, m->time, m->socketid,
+			m->apicid);
+}
+
+static void print_mce_head(void)
+{
+	printk(KERN_EMERG "\n" KERN_EMERG "HARDWARE ERROR\n");
+}
+
+static void print_mce_tail(void)
+{
+	printk(KERN_EMERG "This is not a software problem!\n"
+	       KERN_EMERG "Run through mcelog --ascii to decode and contact your hardware vendor\n");
+}
+
+#define PANIC_TIMEOUT 5 /* 5 seconds */
+
+static atomic_t mce_paniced;
+
+/* Panic in progress. Enable interrupts and wait for final IPI */
+static void wait_for_panic(void)
+{
+	long timeout = PANIC_TIMEOUT*USEC_PER_SEC;
+	preempt_disable();
+	local_irq_enable();
+	while (timeout-- > 0)
+		udelay(1);
+	if (panic_timeout == 0)
+		panic_timeout = mce_panic_timeout;
+	panic("Panicing machine check CPU died");
+}
+
+static void mce_panic(char *msg, struct mce *final, char *exp)
+{
+	int i;
+
+	/*
+	 * Make sure only one CPU runs in machine check panic
+	 */
+	if (atomic_add_return(1, &mce_paniced) > 1)
+		wait_for_panic();
+	barrier();
+
+	bust_spinlocks(1);
+	console_verbose();
+	print_mce_head();
+	/* First print corrected ones that are still unlogged */
+	for (i = 0; i < MCE_LOG_LEN; i++) {
+		struct mce *m = &mcelog.entry[i];
+		if (!(m->status & MCI_STATUS_VAL))
+			continue;
+		if (!(m->status & MCI_STATUS_UC))
+			print_mce(m);
+	}
+	/* Now print uncorrected but with the final one last */
+	for (i = 0; i < MCE_LOG_LEN; i++) {
+		struct mce *m = &mcelog.entry[i];
+		if (!(m->status & MCI_STATUS_VAL))
+			continue;
+		if (!(m->status & MCI_STATUS_UC))
+			continue;
+		if (!final || memcmp(m, final, sizeof(struct mce)))
+			print_mce(m);
+	}
+	if (final)
+		print_mce(final);
+	if (cpu_missing)
+		printk(KERN_EMERG "Some CPUs didn't answer in synchronization\n");
+	print_mce_tail();
+	if (exp)
+		printk(KERN_EMERG "Machine check: %s\n", exp);
+	if (panic_timeout == 0)
+		panic_timeout = mce_panic_timeout;
+	panic(msg);
+}
+
+/* Support code for software error injection */
+
+static int msr_to_offset(u32 msr)
+{
+	unsigned bank = __get_cpu_var(injectm.bank);
+	if (msr == rip_msr)
+		return offsetof(struct mce, ip);
+	if (msr == MSR_IA32_MC0_STATUS + bank*4)
+		return offsetof(struct mce, status);
+	if (msr == MSR_IA32_MC0_ADDR + bank*4)
+		return offsetof(struct mce, addr);
+	if (msr == MSR_IA32_MC0_MISC + bank*4)
+		return offsetof(struct mce, misc);
+	if (msr == MSR_IA32_MCG_STATUS)
+		return offsetof(struct mce, mcgstatus);
+	return -1;
+}
+
+/* MSR access wrappers used for error injection */
+static u64 mce_rdmsrl(u32 msr)
+{
+	u64 v;
+	if (__get_cpu_var(injectm).finished) {
+		int offset = msr_to_offset(msr);
+		if (offset < 0)
+			return 0;
+		return *(u64 *)((char *)&__get_cpu_var(injectm) + offset);
+	}
+	rdmsrl(msr, v);
+	return v;
+}
+
+static void mce_wrmsrl(u32 msr, u64 v)
+{
+	if (__get_cpu_var(injectm).finished) {
+		int offset = msr_to_offset(msr);
+		if (offset >= 0)
+			*(u64 *)((char *)&__get_cpu_var(injectm) + offset) = v;
+		return;
+	}
+	wrmsrl(msr, v);
+}
+
+/*
+ * Simple lockless ring to communicate PFNs from the exception handler with the
+ * process context work function. This is vastly simplified because there's
+ * only a single reader and a single writer.
+ */
+#define MCE_RING_SIZE 16	/* we use one entry less */
+
+struct mce_ring {
+	unsigned short start;
+	unsigned short end;
+	unsigned long ring[MCE_RING_SIZE];
+};
+static DEFINE_PER_CPU(struct mce_ring, mce_ring);
+
+/* Runs with CPU affinity in workqueue */
+static int mce_ring_empty(void)
+{
+	struct mce_ring *r = &__get_cpu_var(mce_ring);
+
+	return r->start == r->end;
+}
+
+static int mce_ring_get(unsigned long *pfn)
+{
+	struct mce_ring *r;
+	int ret = 0;
+
+	*pfn = 0;
+	get_cpu();
+	r = &__get_cpu_var(mce_ring);
+	if (r->start == r->end)
+		goto out;
+	*pfn = r->ring[r->start];
+	r->start = (r->start + 1) % MCE_RING_SIZE;
+	ret = 1;
+out:
+	put_cpu();
+	return ret;
+}
+
+/* Always runs in MCE context with preempt off */
+static int mce_ring_add(unsigned long pfn)
+{
+	struct mce_ring *r = &__get_cpu_var(mce_ring);
+	unsigned next;
+
+	next = (r->end + 1) % MCE_RING_SIZE;
+	if (next == r->start)
+		return -1;
+	r->ring[r->end] = pfn;
+	wmb();
+	r->end = next;
+	return 0;
+}
+
+int mce_available(struct cpuinfo_x86 *c)
+{
+	if (mce_disabled)
+		return 0;
+	return cpu_has(c, X86_FEATURE_MCE) && cpu_has(c, X86_FEATURE_MCA);
+}
+
+static void mce_schedule_work(void)
+{
+	if (!mce_ring_empty()) {
+		struct work_struct *work = &__get_cpu_var(mce_work);
+		if (!work_pending(work))
+			schedule_work(work);
+	}
+}
+
+/*
+ * Get the address of the instruction at the time of the machine check
+ * error.
+ */
+static inline void mce_get_rip(struct mce *m, struct pt_regs *regs)
+{
+
+	if (regs && (m->mcgstatus & (MCG_STATUS_RIPV|MCG_STATUS_EIPV))) {
+		m->ip = regs->ip;
+		m->cs = regs->cs;
+	} else {
+		m->ip = 0;
+		m->cs = 0;
+	}
+	if (rip_msr)
+		m->ip = mce_rdmsrl(rip_msr);
+}
+
+#ifdef CONFIG_X86_LOCAL_APIC 
+/*
+ * Called after interrupts have been reenabled again
+ * when a MCE happened during an interrupts off region
+ * in the kernel.
+ */
+asmlinkage void smp_mce_self_interrupt(struct pt_regs *regs)
+{
+	ack_APIC_irq();
+	exit_idle();
+	irq_enter();
+	mce_notify_irq();
+	mce_schedule_work();
+	irq_exit();
+}
+#endif
+
+static void mce_report_event(struct pt_regs *regs)
+{
+	if (regs->flags & (X86_VM_MASK|X86_EFLAGS_IF)) {
+		mce_notify_irq();
+		/*
+		 * Triggering the work queue here is just an insurance
+		 * policy in case the syscall exit notify handler
+		 * doesn't run soon enough or ends up running on the
+		 * wrong CPU (can happen when audit sleeps)
+		 */
+		mce_schedule_work();
+		return;
+	}
+
+#ifdef CONFIG_X86_LOCAL_APIC
+	/*
+	 * Without APIC do not notify. The event will be picked
+	 * up eventually.
+	 */
+	if (!cpu_has_apic)
+		return;
+
+	/*
+	 * When interrupts are disabled we cannot use
+	 * kernel services safely. Trigger an self interrupt
+	 * through the APIC to instead do the notification
+	 * after interrupts are reenabled again.
+	 */
+	apic->send_IPI_self(MCE_SELF_VECTOR);
+
+	/*
+	 * Wait for idle afterwards again so that we don't leave the
+	 * APIC in a non idle state because the normal APIC writes
+	 * cannot exclude us.
+	 */
+	apic_wait_icr_idle();
+#endif
+}
+
+DEFINE_PER_CPU(unsigned, mce_poll_count);
+
+/*
+ * Poll for corrected events or events that happened before reset.
+ * Those are just logged through /dev/mcelog.
+ *
+ * This is executed in standard interrupt context.
+ *
+ * Note: spec recommends to panic for fatal unsignalled
+ * errors here. However this would be quite problematic --
+ * we would need to reimplement the Monarch handling and
+ * it would mess up the exclusion between exception handler
+ * and poll hander -- * so we skip this for now.
+ * These cases should not happen anyways, or only when the CPU
+ * is already totally * confused. In this case it's likely it will
+ * not fully execute the machine check handler either.
+ */
+void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
+{
+	struct mce m;
+	int i;
+
+	__get_cpu_var(mce_poll_count)++;
+
+	mce_setup(&m);
+
+	m.mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
+	for (i = 0; i < banks; i++) {
+		if (!bank[i] || !test_bit(i, *b))
+			continue;
+
+		m.misc = 0;
+		m.addr = 0;
+		m.bank = i;
+		m.tsc = 0;
+
+		barrier();
+		m.status = mce_rdmsrl(MSR_IA32_MC0_STATUS + i*4);
+		if (!(m.status & MCI_STATUS_VAL))
+			continue;
+
+		/*
+		 * Uncorrected or signalled events are handled by the exception
+		 * handler when it is enabled, so don't process those here.
+		 *
+		 * TBD do the same check for MCI_STATUS_EN here?
+		 */
+		if (!(flags & MCP_UC) &&
+		    (m.status & (mce_ser ? MCI_STATUS_S : MCI_STATUS_UC)))
+			continue;
+
+		if (m.status & MCI_STATUS_MISCV)
+			m.misc = mce_rdmsrl(MSR_IA32_MC0_MISC + i*4);
+		if (m.status & MCI_STATUS_ADDRV)
+			m.addr = mce_rdmsrl(MSR_IA32_MC0_ADDR + i*4);
+
+		if (!(flags & MCP_TIMESTAMP))
+			m.tsc = 0;
+		/*
+		 * Don't get the IP here because it's unlikely to
+		 * have anything to do with the actual error location.
+		 */
+		if (!(flags & MCP_DONTLOG) && !mce_dont_log_ce) {
+			mce_log(&m);
+			add_taint(TAINT_MACHINE_CHECK);
+		}
+
+		/*
+		 * Clear state for this bank.
+		 */
+		mce_wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
+	}
+
+	/*
+	 * Don't clear MCG_STATUS here because it's only defined for
+	 * exceptions.
+	 */
+
+	sync_core();
+}
+EXPORT_SYMBOL_GPL(machine_check_poll);
+
+/*
+ * Do a quick check if any of the events requires a panic.
+ * This decides if we keep the events around or clear them.
+ */
+static int mce_no_way_out(struct mce *m, char **msg)
+{
+	int i;
+
+	for (i = 0; i < banks; i++) {
+		m->status = mce_rdmsrl(MSR_IA32_MC0_STATUS + i*4);
+		if (mce_severity(m, tolerant, msg) >= MCE_PANIC_SEVERITY)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Variable to establish order between CPUs while scanning.
+ * Each CPU spins initially until executing is equal its number.
+ */
+static atomic_t mce_executing;
+
+/*
+ * Defines order of CPUs on entry. First CPU becomes Monarch.
+ */
+static atomic_t mce_callin;
+
+/*
+ * Check if a timeout waiting for other CPUs happened.
+ */
+static int mce_timed_out(u64 *t)
+{
+	/*
+	 * The others already did panic for some reason.
+	 * Bail out like in a timeout.
+	 * rmb() to tell the compiler that system_state
+	 * might have been modified by someone else.
+	 */
+	rmb();
+	if (atomic_read(&mce_paniced))
+		wait_for_panic();
+	if (!monarch_timeout)
+		goto out;
+	if ((s64)*t < SPINUNIT) {
+		/* CHECKME: Make panic default for 1 too? */
+		if (tolerant < 1)
+			mce_panic("Timeout synchronizing machine check over CPUs",
+				  NULL, NULL);
+		cpu_missing = 1;
+		return 1;
+	}
+	*t -= SPINUNIT;
+out:
+	touch_nmi_watchdog();
+	return 0;
+}
+
+/*
+ * The Monarch's reign.  The Monarch is the CPU who entered
+ * the machine check handler first. It waits for the others to
+ * raise the exception too and then grades them. When any
+ * error is fatal panic. Only then let the others continue.
+ *
+ * The other CPUs entering the MCE handler will be controlled by the
+ * Monarch. They are called Subjects.
+ *
+ * This way we prevent any potential data corruption in a unrecoverable case
+ * and also makes sure always all CPU's errors are examined.
+ *
+ * Also this detects the case of an machine check event coming from outer
+ * space (not detected by any CPUs) In this case some external agent wants
+ * us to shut down, so panic too.
+ *
+ * The other CPUs might still decide to panic if the handler happens
+ * in a unrecoverable place, but in this case the system is in a semi-stable
+ * state and won't corrupt anything by itself. It's ok to let the others
+ * continue for a bit first.
+ *
+ * All the spin loops have timeouts; when a timeout happens a CPU
+ * typically elects itself to be Monarch.
+ */
+static void mce_reign(void)
+{
+	int cpu;
+	struct mce *m = NULL;
+	int global_worst = 0;
+	char *msg = NULL;
+	char *nmsg = NULL;
+
+	/*
+	 * This CPU is the Monarch and the other CPUs have run
+	 * through their handlers.
+	 * Grade the severity of the errors of all the CPUs.
+	 */
+	for_each_possible_cpu(cpu) {
+		int severity = mce_severity(&per_cpu(mces_seen, cpu), tolerant,
+					    &nmsg);
+		if (severity > global_worst) {
+			msg = nmsg;
+			global_worst = severity;
+			m = &per_cpu(mces_seen, cpu);
+		}
+	}
+
+	/*
+	 * Cannot recover? Panic here then.
+	 * This dumps all the mces in the log buffer and stops the
+	 * other CPUs.
+	 */
+	if (m && global_worst >= MCE_PANIC_SEVERITY && tolerant < 3)
+		mce_panic("Fatal Machine check", m, msg);
+
+	/*
+	 * For UC somewhere we let the CPU who detects it handle it.
+	 * Also must let continue the others, otherwise the handling
+	 * CPU could deadlock on a lock.
+	 */
+
+	/*
+	 * No machine check event found. Must be some external
+	 * source or one CPU is hung. Panic.
+	 */
+	if (!m && tolerant < 3)
+		mce_panic("Machine check from unknown source", NULL, NULL);
+
+	/*
+	 * Now clear all the mces_seen so that they don't reappear on
+	 * the next mce.
+	 */
+	for_each_possible_cpu(cpu)
+		memset(&per_cpu(mces_seen, cpu), 0, sizeof(struct mce));
+}
+
+static atomic_t global_nwo;
+
+/*
+ * Start of Monarch synchronization. This waits until all CPUs have
+ * entered the exception handler and then determines if any of them
+ * saw a fatal event that requires panic. Then it executes them
+ * in the entry order.
+ * TBD double check parallel CPU hotunplug
+ */
+static int mce_start(int no_way_out, int *order)
+{
+	int nwo;
+	int cpus = num_online_cpus();
+	u64 timeout = (u64)monarch_timeout * NSEC_PER_USEC;
+
+	if (!timeout) {
+		*order = -1;
+		return no_way_out;
+	}
+
+	atomic_add(no_way_out, &global_nwo);
+
+	/*
+	 * Wait for everyone.
+	 */
+	while (atomic_read(&mce_callin) != cpus) {
+		if (mce_timed_out(&timeout)) {
+			atomic_set(&global_nwo, 0);
+			*order = -1;
+			return no_way_out;
+		}
+		ndelay(SPINUNIT);
+	}
+
+	/*
+	 * Cache the global no_way_out state.
+	 */
+	nwo = atomic_read(&global_nwo);
+
+	/*
+	 * Monarch starts executing now, the others wait.
+	 */
+	if (*order == 1) {
+		atomic_set(&mce_executing, 1);
+		return nwo;
+	}
+
+	/*
+	 * Now start the scanning loop one by one
+	 * in the original callin order.
+	 * This way when there are any shared banks it will
+	 * be only seen by one CPU before cleared, avoiding duplicates.
+	 */
+	while (atomic_read(&mce_executing) < *order) {
+		if (mce_timed_out(&timeout)) {
+			atomic_set(&global_nwo, 0);
+			*order = -1;
+			return no_way_out;
+		}
+		ndelay(SPINUNIT);
+	}
+	return nwo;
+}
+
+/*
+ * Synchronize between CPUs after main scanning loop.
+ * This invokes the bulk of the Monarch processing.
+ */
+static int mce_end(int order)
+{
+	int ret = -1;
+	u64 timeout = (u64)monarch_timeout * NSEC_PER_USEC;
+
+	if (!timeout)
+		goto reset;
+	if (order < 0)
+		goto reset;
+
+	/*
+	 * Allow others to run.
+	 */
+	atomic_inc(&mce_executing);
+
+	if (order == 1) {
+		/* CHECKME: Can this race with a parallel hotplug? */
+		int cpus = num_online_cpus();
+
+		/*
+		 * Monarch: Wait for everyone to go through their scanning
+		 * loops.
+		 */
+		while (atomic_read(&mce_executing) <= cpus) {
+			if (mce_timed_out(&timeout))
+				goto reset;
+			ndelay(SPINUNIT);
+		}
+
+		mce_reign();
+		barrier();
+		ret = 0;
+	} else {
+		/*
+		 * Subject: Wait for Monarch to finish.
+		 */
+		while (atomic_read(&mce_executing) != 0) {
+			if (mce_timed_out(&timeout))
+				goto reset;
+			ndelay(SPINUNIT);
+		}
+
+		/*
+		 * Don't reset anything. That's done by the Monarch.
+		 */
+		return 0;
+	}
+
+	/*
+	 * Reset all global state.
+	 */
+reset:
+	atomic_set(&global_nwo, 0);
+	atomic_set(&mce_callin, 0);
+	barrier();
+
+	/*
+	 * Let others run again.
+	 */
+	atomic_set(&mce_executing, 0);
+	return ret;
+}
+
+/*
+ * Check if the address reported by the CPU is in a format we can parse.
+ * It would be possible to add code for most other cases, but all would
+ * be somewhat complicated (e.g. segment offset would require an instruction
+ * parser). So only support physical addresses upto page granuality for now.
+ */
+static int mce_usable_address(struct mce *m)
+{
+	if (!(m->status & MCI_STATUS_MISCV) || !(m->status & MCI_STATUS_ADDRV))
+		return 0;
+	if ((m->misc & 0x3f) > PAGE_SHIFT)
+		return 0;
+	if (((m->misc >> 6) & 7) != MCM_ADDR_PHYS)
+		return 0;
+	return 1;
+}
+
+static void mce_clear_state(unsigned long *toclear)
+{
+	int i;
+
+	for (i = 0; i < banks; i++) {
+		if (test_bit(i, toclear))
+			mce_wrmsrl(MSR_IA32_MC0_STATUS+4*i, 0);
+	}
+}
+
+/*
+ * The actual machine check handler. This only handles real
+ * exceptions when something got corrupted coming in through int 18.
+ *
+ * This is executed in NMI context not subject to normal locking rules. This
+ * implies that most kernel services cannot be safely used. Don't even
+ * think about putting a printk in there!
+ *
+ * On Intel systems this is entered on all CPUs in parallel through
+ * MCE broadcast. However some CPUs might be broken beyond repair,
+ * so be always careful when synchronizing with others.
+ */
+void do_machine_check(struct pt_regs *regs, long error_code)
+{
+	struct mce m, *final;
+	int i;
+	int worst = 0;
+	int severity;
+	/*
+	 * Establish sequential order between the CPUs entering the machine
+	 * check handler.
+	 */
+	int order;
+
+	/*
+	 * 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;
+	DECLARE_BITMAP(toclear, MAX_NR_BANKS);
+	char *msg = "Unknown";
+
+	atomic_inc(&mce_entry);
+
+	__get_cpu_var(mce_exception_count)++;
+
+	if (notify_die(DIE_NMI, "machine check", regs, error_code,
+			   18, SIGKILL) == NOTIFY_STOP)
+		goto out;
+	if (!banks)
+		goto out;
+
+	order = atomic_add_return(1, &mce_callin);
+	mce_setup(&m);
+
+	m.mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
+	no_way_out = mce_no_way_out(&m, &msg);
+
+	final = &__get_cpu_var(mces_seen);
+	*final = m;
+
+	barrier();
+
+	/*
+	 * When no restart IP must always kill or panic.
+	 */
+	if (!(m.mcgstatus & MCG_STATUS_RIPV))
+		kill_it = 1;
+
+	/*
+	 * Go through all the banks in exclusion of the other CPUs.
+	 * This way we don't report duplicated events on shared banks
+	 * because the first one to see it will clear it.
+	 */
+	no_way_out = mce_start(no_way_out, &order);
+	for (i = 0; i < banks; i++) {
+		__clear_bit(i, toclear);
+		if (!bank[i])
+			continue;
+
+		m.misc = 0;
+		m.addr = 0;
+		m.bank = i;
+
+		m.status = mce_rdmsrl(MSR_IA32_MC0_STATUS + i*4);
+		if ((m.status & MCI_STATUS_VAL) == 0)
+			continue;
+
+		/*
+		 * Non uncorrected or non signaled errors are handled by
+		 * machine_check_poll. Leave them alone, unless this panics.
+		 */
+		if (!(m.status & (mce_ser ? MCI_STATUS_S : MCI_STATUS_UC)) &&
+			!no_way_out)
+			continue;
+
+		/*
+		 * Set taint even when machine check was not enabled.
+		 */
+		add_taint(TAINT_MACHINE_CHECK);
+
+		severity = mce_severity(&m, tolerant, NULL);
+
+		/*
+		 * When machine check was for corrected handler don't touch,
+		 * unless we're panicing.
+		 */
+		if (severity == MCE_KEEP_SEVERITY && !no_way_out)
+			continue;
+		__set_bit(i, toclear);
+		if (severity == MCE_NO_SEVERITY) {
+			/*
+			 * Machine check event was not enabled. Clear, but
+			 * ignore.
+			 */
+			continue;
+		}
+
+		/*
+		 * Kill on action required.
+		 */
+		if (severity == MCE_AR_SEVERITY)
+			kill_it = 1;
+
+		if (m.status & MCI_STATUS_MISCV)
+			m.misc = mce_rdmsrl(MSR_IA32_MC0_MISC + i*4);
+		if (m.status & MCI_STATUS_ADDRV)
+			m.addr = mce_rdmsrl(MSR_IA32_MC0_ADDR + i*4);
+
+		/*
+		 * Action optional error. Queue address for later processing.
+		 * When the ring overflows we just ignore the AO error.
+		 * RED-PEN add some logging mechanism when
+		 * usable_address or mce_add_ring fails.
+		 * RED-PEN don't ignore overflow for tolerant == 0
+		 */
+		if (severity == MCE_AO_SEVERITY && mce_usable_address(&m))
+			mce_ring_add(m.addr >> PAGE_SHIFT);
+
+		mce_get_rip(&m, regs);
+		mce_log(&m);
+
+		if (severity > worst) {
+			*final = m;
+			worst = severity;
+		}
+	}
+
+	if (!no_way_out)
+		mce_clear_state(toclear);
+
+	/*
+	 * Do most of the synchronization with other CPUs.
+	 * When there's any problem use only local no_way_out state.
+	 */
+	if (mce_end(order) < 0)
+		no_way_out = worst >= MCE_PANIC_SEVERITY;
+
+	/*
+	 * 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.
+	 *
+	 * This is mainly used in the case when the system doesn't
+	 * support MCE broadcasting or it has been disabled.
+	 */
+	if (no_way_out && tolerant < 3)
+		mce_panic("Fatal machine check on current CPU", final, msg);
+
+	/*
+	 * 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)
+		force_sig(SIGBUS, current);
+
+	/* notify userspace ASAP */
+	set_thread_flag(TIF_MCE_NOTIFY);
+
+	if (worst > 0)
+		mce_report_event(regs);
+	mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
+out:
+	atomic_dec(&mce_entry);
+	sync_core();
+}
+EXPORT_SYMBOL_GPL(do_machine_check);
+
+/* dummy to break dependency. actual code is in mm/memory-failure.c */
+void __attribute__((weak)) memory_failure(unsigned long pfn, int vector)
+{
+	printk(KERN_ERR "Action optional memory failure at %lx ignored\n", pfn);
+}
+
+/*
+ * Called after mce notification in process context. This code
+ * is allowed to sleep. Call the high level VM handler to process
+ * any corrupted pages.
+ * Assume that the work queue code only calls this one at a time
+ * per CPU.
+ * Note we don't disable preemption, so this code might run on the wrong
+ * CPU. In this case the event is picked up by the scheduled work queue.
+ * This is merely a fast path to expedite processing in some common
+ * cases.
+ */
+void mce_notify_process(void)
+{
+	unsigned long pfn;
+	mce_notify_irq();
+	while (mce_ring_get(&pfn))
+		memory_failure(pfn, MCE_VECTOR);
+}
+
+static void mce_process_work(struct work_struct *dummy)
+{
+	mce_notify_process();
+}
+
+#ifdef CONFIG_X86_MCE_INTEL
+/***
+ * mce_log_therm_throt_event - Logs the thermal throttling event to mcelog
+ * @cpu: The CPU on which the event occurred.
+ * @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(__u64 status)
+{
+	struct mce m;
+
+	mce_setup(&m);
+	m.bank = MCE_THERMAL_BANK;
+	m.status = status;
+	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 DEFINE_PER_CPU(int, next_interval); /* in jiffies */
+static DEFINE_PER_CPU(struct timer_list, mce_timer);
+
+static void mcheck_timer(unsigned long data)
+{
+	struct timer_list *t = &per_cpu(mce_timer, data);
+	int *n;
+
+	WARN_ON(smp_processor_id() != data);
+
+	if (mce_available(&current_cpu_data)) {
+		machine_check_poll(MCP_TIMESTAMP,
+				&__get_cpu_var(mce_poll_banks));
+	}
+
+	/*
+	 * Alert userspace if needed.  If we logged an MCE, reduce the
+	 * polling interval, otherwise increase the polling interval.
+	 */
+	n = &__get_cpu_var(next_interval);
+	if (mce_notify_irq())
+		*n = max(*n/2, HZ/100);
+	else
+		*n = min(*n*2, (int)round_jiffies_relative(check_interval*HZ));
+
+	t->expires = jiffies + *n;
+	add_timer(t);
+}
+
+static void mce_do_trigger(struct work_struct *work)
+{
+	call_usermodehelper(trigger, trigger_argv, NULL, UMH_NO_WAIT);
+}
+
+static DECLARE_WORK(mce_trigger_work, mce_do_trigger);
+
+/*
+ * Notify the user(s) about new machine check events.
+ * Can be called from interrupt context, but not from machine check/NMI
+ * context.
+ */
+int mce_notify_irq(void)
+{
+	/* Not more than two messages every minute */
+	static DEFINE_RATELIMIT_STATE(ratelimit, 60*HZ, 2);
+
+	clear_thread_flag(TIF_MCE_NOTIFY);
+
+	if (test_and_clear_bit(0, &notify_user)) {
+		wake_up_interruptible(&mce_wait);
+
+		/*
+		 * There is no risk of missing notifications because
+		 * work_pending is always cleared before the function is
+		 * executed.
+		 */
+		if (trigger[0] && !work_pending(&mce_trigger_work))
+			schedule_work(&mce_trigger_work);
+
+		if (__ratelimit(&ratelimit))
+			printk(KERN_INFO "Machine check events logged\n");
+
+		return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mce_notify_irq);
+
+/*
+ * Initialize Machine Checks for a CPU.
+ */
+static int mce_cap_init(void)
+{
+	unsigned b;
+	u64 cap;
+
+	rdmsrl(MSR_IA32_MCG_CAP, cap);
+
+	b = cap & MCG_BANKCNT_MASK;
+	printk(KERN_INFO "mce: CPU supports %d MCE banks\n", b);
+
+	if (b > MAX_NR_BANKS) {
+		printk(KERN_WARNING
+		       "MCE: Using only %u machine check banks out of %u\n",
+			MAX_NR_BANKS, b);
+		b = MAX_NR_BANKS;
+	}
+
+	/* Don't support asymmetric configurations today */
+	WARN_ON(banks != 0 && b != banks);
+	banks = b;
+	if (!bank) {
+		bank = kmalloc(banks * sizeof(u64), GFP_KERNEL);
+		if (!bank)
+			return -ENOMEM;
+		memset(bank, 0xff, banks * sizeof(u64));
+	}
+
+	/* Use accurate RIP reporting if available. */
+	if ((cap & MCG_EXT_P) && MCG_EXT_CNT(cap) >= 9)
+		rip_msr = MSR_IA32_MCG_EIP;
+
+	if (cap & MCG_SER_P)
+		mce_ser = 1;
+
+	return 0;
+}
+
+static void mce_init(void)
+{
+	mce_banks_t all_banks;
+	u64 cap;
+	int i;
+
+	/*
+	 * Log the machine checks left over from the previous reset.
+	 */
+	bitmap_fill(all_banks, MAX_NR_BANKS);
+	machine_check_poll(MCP_UC|(!mce_bootlog ? MCP_DONTLOG : 0), &all_banks);
+
+	set_in_cr4(X86_CR4_MCE);
+
+	rdmsrl(MSR_IA32_MCG_CAP, cap);
+	if (cap & MCG_CTL_P)
+		wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff);
+
+	for (i = 0; i < banks; i++) {
+		if (skip_bank_init(i))
+			continue;
+		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 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) {
+		if (c->x86 == 15 && banks > 4) {
+			/*
+			 * disable GART TBL walk error reporting, which
+			 * trips off incorrectly with the IOMMU & 3ware
+			 * & Cerberus:
+			 */
+			clear_bit(10, (unsigned long *)&bank[4]);
+		}
+		if (c->x86 <= 17 && mce_bootlog < 0) {
+			/*
+			 * Lots of broken BIOS around that don't clear them
+			 * by default and leave crap in there. Don't log:
+			 */
+			mce_bootlog = 0;
+		}
+		/*
+		 * Various K7s with broken bank 0 around. Always disable
+		 * by default.
+		 */
+		 if (c->x86 == 6)
+			bank[0] = 0;
+	}
+
+	if (c->x86_vendor == X86_VENDOR_INTEL) {
+		/*
+		 * SDM documents that on family 6 bank 0 should not be written
+		 * because it aliases to another special BIOS controlled
+		 * register.
+		 * But it's not aliased anymore on model 0x1a+
+		 * Don't ignore bank 0 completely because there could be a
+		 * valid event later, merely don't write CTL0.
+		 */
+
+		if (c->x86 == 6 && c->x86_model < 0x1A)
+			__set_bit(0, &dont_init_banks);
+
+		/*
+		 * All newer Intel systems support MCE broadcasting. Enable
+		 * synchronization with a one second timeout.
+		 */
+		if ((c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xe)) &&
+			monarch_timeout < 0)
+			monarch_timeout = USEC_PER_SEC;
+	}
+	if (monarch_timeout < 0)
+		monarch_timeout = 0;
+	if (mce_bootlog != 0)
+		mce_panic_timeout = 30;
+}
+
+static void __cpuinit mce_ancient_init(struct cpuinfo_x86 *c)
+{
+	if (c->x86 != 5)
+		return;
+	switch (c->x86_vendor) {
+	case X86_VENDOR_INTEL:
+		if (mce_p5_enabled())
+			intel_p5_mcheck_init(c);
+		break;
+	case X86_VENDOR_CENTAUR:
+		winchip_mcheck_init(c);
+		break;
+	}
+}
+
+static void 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;
+	}
+}
+
+static void mce_init_timer(void)
+{
+	struct timer_list *t = &__get_cpu_var(mce_timer);
+	int *n = &__get_cpu_var(next_interval);
+
+	if (mce_ignore_ce)
+		return;
+
+	*n = check_interval * HZ;
+	if (!*n)
+		return;
+	setup_timer(t, mcheck_timer, smp_processor_id());
+	t->expires = round_jiffies(jiffies + *n);
+	add_timer(t);
+}
+
+/*
+ * Called for each booted CPU to set up machine checks.
+ * Must be called with preempt off:
+ */
+void __cpuinit mcheck_init(struct cpuinfo_x86 *c)
+{
+	if (mce_disabled)
+		return;
+
+	mce_ancient_init(c);
+
+	if (!mce_available(c))
+		return;
+
+	if (mce_cap_init() < 0) {
+		mce_disabled = 1;
+		return;
+	}
+	mce_cpu_quirks(c);
+
+	machine_check_vector = do_machine_check;
+
+	mce_init();
+	mce_cpu_features(c);
+	mce_init_timer();
+	INIT_WORK(&__get_cpu_var(mce_work), mce_process_work);
+}
+
+/*
+ * 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 DEFINE_MUTEX(mce_read_mutex);
+
+static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize,
+			loff_t *off)
+{
+	char __user *buf = ubuf;
+	unsigned long *cpu_tsc;
+	unsigned prev, next;
+	int i, err;
+
+	cpu_tsc = kmalloc(nr_cpu_ids * sizeof(long), GFP_KERNEL);
+	if (!cpu_tsc)
+		return -ENOMEM;
+
+	mutex_lock(&mce_read_mutex);
+	next = rcu_dereference(mcelog.next);
+
+	/* Only supports full reads right now */
+	if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce)) {
+		mutex_unlock(&mce_read_mutex);
+		kfree(cpu_tsc);
+
+		return -EINVAL;
+	}
+
+	err = 0;
+	prev = 0;
+	do {
+		for (i = prev; 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 + prev, 0,
+		       (next - prev) * sizeof(struct mce));
+		prev = next;
+		next = cmpxchg(&mcelog.next, prev, 0);
+	} while (next != prev);
+
+	synchronize_sched();
+
+	/*
+	 * Collect entries that were still getting written before the
+	 * synchronize.
+	 */
+	on_each_cpu(collect_tscs, cpu_tsc, 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));
+		}
+	}
+	mutex_unlock(&mce_read_mutex);
+	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 long mce_ioctl(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;
+	}
+}
+
+/* Modified in mce-inject.c, so not static or const */
+struct file_operations mce_chrdev_ops = {
+	.open			= mce_open,
+	.release		= mce_release,
+	.read			= mce_read,
+	.poll			= mce_poll,
+	.unlocked_ioctl		= mce_ioctl,
+};
+EXPORT_SYMBOL_GPL(mce_chrdev_ops);
+
+static struct miscdevice mce_log_device = {
+	MISC_MCELOG_MINOR,
+	"mcelog",
+	&mce_chrdev_ops,
+};
+
+/*
+ * mce=off Disables machine check
+ * mce=no_cmci Disables CMCI
+ * mce=dont_log_ce Clears corrected events silently, no log created for CEs.
+ * mce=ignore_ce Disables polling and CMCI, corrected events are not cleared.
+ * mce=TOLERANCELEVEL[,monarchtimeout] (number, see above)
+ *	monarchtimeout is how long to wait for other CPUs on machine
+ *	check, or 0 to not wait
+ * 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 == 0)
+		enable_p5_mce();
+	if (*str == '=')
+		str++;
+	if (!strcmp(str, "off"))
+		mce_disabled = 1;
+	else if (!strcmp(str, "no_cmci"))
+		mce_cmci_disabled = 1;
+	else if (!strcmp(str, "dont_log_ce"))
+		mce_dont_log_ce = 1;
+	else if (!strcmp(str, "ignore_ce"))
+		mce_ignore_ce = 1;
+	else if (!strcmp(str, "bootlog") || !strcmp(str, "nobootlog"))
+		mce_bootlog = (str[0] == 'b');
+	else if (isdigit(str[0])) {
+		get_option(&str, &tolerant);
+		if (*str == ',') {
+			++str;
+			get_option(&str, &monarch_timeout);
+		}
+	} else {
+		printk(KERN_INFO "mce argument %s ignored. Please use /sys\n",
+		       str);
+		return 0;
+	}
+	return 1;
+}
+__setup("mce", mcheck_enable);
+
+/*
+ * Sysfs support
+ */
+
+/*
+ * Disable machine checks on suspend and shutdown. We can't really handle
+ * them later.
+ */
+static int mce_disable(void)
+{
+	int i;
+
+	for (i = 0; i < banks; i++) {
+		if (!skip_bank_init(i))
+			wrmsrl(MSR_IA32_MC0_CTL + i*4, 0);
+	}
+	return 0;
+}
+
+static int mce_suspend(struct sys_device *dev, pm_message_t state)
+{
+	return mce_disable();
+}
+
+static int mce_shutdown(struct sys_device *dev)
+{
+	return mce_disable();
+}
+
+/*
+ * 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 re-added later using
+ * CPU hotplug:
+ */
+static int mce_resume(struct sys_device *dev)
+{
+	mce_init();
+	mce_cpu_features(&current_cpu_data);
+
+	return 0;
+}
+
+static void mce_cpu_restart(void *data)
+{
+	del_timer_sync(&__get_cpu_var(mce_timer));
+	if (mce_available(&current_cpu_data))
+		mce_init();
+	mce_init_timer();
+}
+
+/* Reinit MCEs after user configuration changes */
+static void mce_restart(void)
+{
+	on_each_cpu(mce_cpu_restart, NULL, 1);
+}
+
+static struct sysdev_class mce_sysclass = {
+	.suspend	= mce_suspend,
+	.shutdown	= mce_shutdown,
+	.resume		= mce_resume,
+	.name		= "machinecheck",
+};
+
+DEFINE_PER_CPU(struct sys_device, mce_dev);
+
+__cpuinitdata
+void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu);
+
+static struct sysdev_attribute *bank_attrs;
+
+static ssize_t show_bank(struct sys_device *s, struct sysdev_attribute *attr,
+			 char *buf)
+{
+	u64 b = bank[attr - bank_attrs];
+
+	return sprintf(buf, "%llx\n", b);
+}
+
+static ssize_t set_bank(struct sys_device *s, struct sysdev_attribute *attr,
+			const char *buf, size_t size)
+{
+	u64 new;
+
+	if (strict_strtoull(buf, 0, &new) < 0)
+		return -EINVAL;
+
+	bank[attr - bank_attrs] = new;
+	mce_restart();
+
+	return size;
+}
+
+static ssize_t
+show_trigger(struct sys_device *s, struct sysdev_attribute *attr, char *buf)
+{
+	strcpy(buf, trigger);
+	strcat(buf, "\n");
+	return strlen(trigger) + 1;
+}
+
+static ssize_t set_trigger(struct sys_device *s, struct sysdev_attribute *attr,
+				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 ssize_t store_int_with_restart(struct sys_device *s,
+				      struct sysdev_attribute *attr,
+				      const char *buf, size_t size)
+{
+	ssize_t ret = sysdev_store_int(s, attr, buf, size);
+	mce_restart();
+	return ret;
+}
+
+static SYSDEV_ATTR(trigger, 0644, show_trigger, set_trigger);
+static SYSDEV_INT_ATTR(tolerant, 0644, tolerant);
+static SYSDEV_INT_ATTR(monarch_timeout, 0644, monarch_timeout);
+
+static struct sysdev_ext_attribute attr_check_interval = {
+	_SYSDEV_ATTR(check_interval, 0644, sysdev_show_int,
+		     store_int_with_restart),
+	&check_interval
+};
+
+static struct sysdev_attribute *mce_attrs[] = {
+	&attr_tolerant.attr, &attr_check_interval.attr, &attr_trigger,
+	&attr_monarch_timeout.attr,
+	NULL
+};
+
+static cpumask_var_t mce_dev_initialized;
+
+/* Per cpu sysdev init. All of the cpus still share the same ctrl bank: */
+static __cpuinit int mce_create_device(unsigned int cpu)
+{
+	int err;
+	int i;
+
+	if (!mce_available(&boot_cpu_data))
+		return -EIO;
+
+	memset(&per_cpu(mce_dev, cpu).kobj, 0, sizeof(struct kobject));
+	per_cpu(mce_dev, cpu).id	= cpu;
+	per_cpu(mce_dev, cpu).cls	= &mce_sysclass;
+
+	err = sysdev_register(&per_cpu(mce_dev, cpu));
+	if (err)
+		return err;
+
+	for (i = 0; mce_attrs[i]; i++) {
+		err = sysdev_create_file(&per_cpu(mce_dev, cpu), mce_attrs[i]);
+		if (err)
+			goto error;
+	}
+	for (i = 0; i < banks; i++) {
+		err = sysdev_create_file(&per_cpu(mce_dev, cpu),
+					&bank_attrs[i]);
+		if (err)
+			goto error2;
+	}
+	cpumask_set_cpu(cpu, mce_dev_initialized);
+
+	return 0;
+error2:
+	while (--i >= 0)
+		sysdev_remove_file(&per_cpu(mce_dev, cpu), &bank_attrs[i]);
+error:
+	while (--i >= 0)
+		sysdev_remove_file(&per_cpu(mce_dev, cpu), mce_attrs[i]);
+
+	sysdev_unregister(&per_cpu(mce_dev, cpu));
+
+	return err;
+}
+
+static __cpuinit void mce_remove_device(unsigned int cpu)
+{
+	int i;
+
+	if (!cpumask_test_cpu(cpu, mce_dev_initialized))
+		return;
+
+	for (i = 0; mce_attrs[i]; i++)
+		sysdev_remove_file(&per_cpu(mce_dev, cpu), mce_attrs[i]);
+
+	for (i = 0; i < banks; i++)
+		sysdev_remove_file(&per_cpu(mce_dev, cpu), &bank_attrs[i]);
+
+	sysdev_unregister(&per_cpu(mce_dev, cpu));
+	cpumask_clear_cpu(cpu, mce_dev_initialized);
+}
+
+/* Make sure there are no machine checks on offlined CPUs. */
+static void mce_disable_cpu(void *h)
+{
+	unsigned long action = *(unsigned long *)h;
+	int i;
+
+	if (!mce_available(&current_cpu_data))
+		return;
+	if (!(action & CPU_TASKS_FROZEN))
+		cmci_clear();
+	for (i = 0; i < banks; i++) {
+		if (!skip_bank_init(i))
+			wrmsrl(MSR_IA32_MC0_CTL + i*4, 0);
+	}
+}
+
+static void mce_reenable_cpu(void *h)
+{
+	unsigned long action = *(unsigned long *)h;
+	int i;
+
+	if (!mce_available(&current_cpu_data))
+		return;
+
+	if (!(action & CPU_TASKS_FROZEN))
+		cmci_reenable();
+	for (i = 0; i < banks; i++) {
+		if (!skip_bank_init(i))
+			wrmsrl(MSR_IA32_MC0_CTL + i*4, bank[i]);
+	}
+}
+
+/* Get notified when a cpu comes on/off. Be hotplug friendly. */
+static int __cpuinit
+mce_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned long)hcpu;
+	struct timer_list *t = &per_cpu(mce_timer, cpu);
+
+	switch (action) {
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		mce_create_device(cpu);
+		if (threshold_cpu_callback)
+			threshold_cpu_callback(action, cpu);
+		break;
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+		if (threshold_cpu_callback)
+			threshold_cpu_callback(action, cpu);
+		mce_remove_device(cpu);
+		break;
+	case CPU_DOWN_PREPARE:
+	case CPU_DOWN_PREPARE_FROZEN:
+		del_timer_sync(t);
+		smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
+		break;
+	case CPU_DOWN_FAILED:
+	case CPU_DOWN_FAILED_FROZEN:
+		t->expires = round_jiffies(jiffies +
+						__get_cpu_var(next_interval));
+		add_timer_on(t, cpu);
+		smp_call_function_single(cpu, mce_reenable_cpu, &action, 1);
+		break;
+	case CPU_POST_DEAD:
+		/* intentionally ignoring frozen here */
+		cmci_rediscover(cpu);
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block mce_cpu_notifier __cpuinitdata = {
+	.notifier_call = mce_cpu_callback,
+};
+
+static __init int mce_init_banks(void)
+{
+	int i;
+
+	bank_attrs = kzalloc(sizeof(struct sysdev_attribute) * banks,
+				GFP_KERNEL);
+	if (!bank_attrs)
+		return -ENOMEM;
+
+	for (i = 0; i < banks; i++) {
+		struct sysdev_attribute *a = &bank_attrs[i];
+
+		a->attr.name	= kasprintf(GFP_KERNEL, "bank%d", i);
+		if (!a->attr.name)
+			goto nomem;
+
+		a->attr.mode	= 0644;
+		a->show		= show_bank;
+		a->store	= set_bank;
+	}
+	return 0;
+
+nomem:
+	while (--i >= 0)
+		kfree(bank_attrs[i].attr.name);
+	kfree(bank_attrs);
+	bank_attrs = NULL;
+
+	return -ENOMEM;
+}
+
+static __init int mce_init_device(void)
+{
+	int err;
+	int i = 0;
+
+	if (!mce_available(&boot_cpu_data))
+		return -EIO;
+
+	alloc_cpumask_var(&mce_dev_initialized, GFP_KERNEL);
+
+	err = mce_init_banks();
+	if (err)
+		return err;
+
+	err = sysdev_class_register(&mce_sysclass);
+	if (err)
+		return err;
+
+	for_each_online_cpu(i) {
+		err = mce_create_device(i);
+		if (err)
+			return err;
+	}
+
+	register_hotcpu_notifier(&mce_cpu_notifier);
+	misc_register(&mce_log_device);
+
+	return err;
+}
+
+device_initcall(mce_init_device);
+
+#else /* CONFIG_X86_OLD_MCE: */
+
+int nr_mce_banks;
+EXPORT_SYMBOL_GPL(nr_mce_banks);	/* non-fatal.o */
+
+/* This has to be run for each processor */
+void mcheck_init(struct cpuinfo_x86 *c)
+{
+	if (mce_disabled == 1)
+		return;
+
+	switch (c->x86_vendor) {
+	case X86_VENDOR_AMD:
+		amd_mcheck_init(c);
+		break;
+
+	case X86_VENDOR_INTEL:
+		if (c->x86 == 5)
+			intel_p5_mcheck_init(c);
+		if (c->x86 == 6)
+			intel_p6_mcheck_init(c);
+		if (c->x86 == 15)
+			intel_p4_mcheck_init(c);
+		break;
+
+	case X86_VENDOR_CENTAUR:
+		if (c->x86 == 5)
+			winchip_mcheck_init(c);
+		break;
+
+	default:
+		break;
+	}
+	printk(KERN_INFO "mce: CPU supports %d MCE banks\n", nr_mce_banks);
+}
+
+static int __init mcheck_enable(char *str)
+{
+	mce_disabled = -1;
+	return 1;
+}
+
+__setup("mce", mcheck_enable);
+
+#endif /* CONFIG_X86_OLD_MCE */
+
+/*
+ * Old style boot options parsing. Only for compatibility.
+ */
+static int __init mcheck_disable(char *str)
+{
+	mce_disabled = 1;
+	return 1;
+}
+__setup("nomce", mcheck_disable);