Initial import

1 files changed, 2566 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 000000000..20190bdac
--- /dev/null
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -0,0 +1,2566 @@
+/*
+ * 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
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/thread_info.h>
+#include <linux/capability.h>
+#include <linux/miscdevice.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/device.h>
+#include <linux/syscore_ops.h>
+#include <linux/delay.h>
+#include <linux/ctype.h>
+#include <linux/sched.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+#include <linux/slab.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 <linux/debugfs.h>
+#include <linux/irq_work.h>
+#include <linux/export.h>
+
+#include <asm/processor.h>
+#include <asm/traps.h>
+#include <asm/tlbflush.h>
+#include <asm/mce.h>
+#include <asm/msr.h>
+
+#include "mce-internal.h"
+
+static DEFINE_MUTEX(mce_chrdev_read_mutex);
+
+#define rcu_dereference_check_mce(p) \
+	rcu_dereference_index_check((p), \
+			      rcu_read_lock_sched_held() || \
+			      lockdep_is_held(&mce_chrdev_read_mutex))
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/mce.h>
+
+#define SPINUNIT		100	/* 100ns */
+
+DEFINE_PER_CPU(unsigned, mce_exception_count);
+
+struct mce_bank *mce_banks __read_mostly;
+struct mce_vendor_flags mce_flags __read_mostly;
+
+struct mca_config mca_cfg __read_mostly = {
+	.bootlog  = -1,
+	/*
+	 * 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 corr. errors
+	 * 3: never panic or SIGBUS, log all errors (for testing only)
+	 */
+	.tolerant = 1,
+	.monarch_timeout = -1
+};
+
+/* User mode helper program triggered by machine check event */
+static unsigned long		mce_need_notify;
+static char			mce_helper[128];
+static char			*mce_helper_argv[2] = { mce_helper, NULL };
+
+static DECLARE_WAIT_QUEUE_HEAD(mce_chrdev_wait);
+
+static DEFINE_PER_CPU(struct mce, mces_seen);
+static int			cpu_missing;
+
+/*
+ * MCA banks polled by the period polling timer for corrected events.
+ * With Intel CMCI, this only has MCA banks which do not support CMCI (if any).
+ */
+DEFINE_PER_CPU(mce_banks_t, mce_poll_banks) = {
+	[0 ... BITS_TO_LONGS(MAX_NR_BANKS)-1] = ~0UL
+};
+
+/*
+ * MCA banks controlled through firmware first for corrected errors.
+ * This is a global list of banks for which we won't enable CMCI and we
+ * won't poll. Firmware controls these banks and is responsible for
+ * reporting corrected errors through GHES. Uncorrected/recoverable
+ * errors are still notified through a machine check.
+ */
+mce_banks_t mce_banks_ce_disabled;
+
+static DEFINE_PER_CPU(struct work_struct, mce_work);
+
+static void (*quirk_no_way_out)(int bank, struct mce *m, struct pt_regs *regs);
+
+/*
+ * CPU/chipset specific EDAC code can register a notifier call here to print
+ * MCE errors in a human-readable form.
+ */
+static ATOMIC_NOTIFIER_HEAD(x86_mce_decoder_chain);
+
+/* 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);
+	m->socketid = cpu_data(m->extcpu).phys_proc_id;
+	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;
+
+	/* Emit the trace record: */
+	trace_mce_record(mce);
+
+	atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, mce);
+
+	mce->finished = 0;
+	wmb();
+	for (;;) {
+		entry = rcu_dereference_check_mce(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, &mce_need_notify);
+}
+
+static void drain_mcelog_buffer(void)
+{
+	unsigned int next, i, prev = 0;
+
+	next = ACCESS_ONCE(mcelog.next);
+
+	do {
+		struct mce *m;
+
+		/* drain what was logged during boot */
+		for (i = prev; i < next; i++) {
+			unsigned long start = jiffies;
+			unsigned retries = 1;
+
+			m = &mcelog.entry[i];
+
+			while (!m->finished) {
+				if (time_after_eq(jiffies, start + 2*retries))
+					retries++;
+
+				cpu_relax();
+
+				if (!m->finished && retries >= 4) {
+					pr_err("skipping error being logged currently!\n");
+					break;
+				}
+			}
+			smp_rmb();
+			atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m);
+		}
+
+		memset(mcelog.entry + prev, 0, (next - prev) * sizeof(*m));
+		prev = next;
+		next = cmpxchg(&mcelog.next, prev, 0);
+	} while (next != prev);
+}
+
+
+void mce_register_decode_chain(struct notifier_block *nb)
+{
+	atomic_notifier_chain_register(&x86_mce_decoder_chain, nb);
+	drain_mcelog_buffer();
+}
+EXPORT_SYMBOL_GPL(mce_register_decode_chain);
+
+void mce_unregister_decode_chain(struct notifier_block *nb)
+{
+	atomic_notifier_chain_unregister(&x86_mce_decoder_chain, nb);
+}
+EXPORT_SYMBOL_GPL(mce_unregister_decode_chain);
+
+static void print_mce(struct mce *m)
+{
+	int ret = 0;
+
+	pr_emerg(HW_ERR "CPU %d: Machine Check Exception: %Lx Bank %d: %016Lx\n",
+	       m->extcpu, m->mcgstatus, m->bank, m->status);
+
+	if (m->ip) {
+		pr_emerg(HW_ERR "RIP%s %02x:<%016Lx> ",
+			!(m->mcgstatus & MCG_STATUS_EIPV) ? " !INEXACT!" : "",
+				m->cs, m->ip);
+
+		if (m->cs == __KERNEL_CS)
+			print_symbol("{%s}", m->ip);
+		pr_cont("\n");
+	}
+
+	pr_emerg(HW_ERR "TSC %llx ", m->tsc);
+	if (m->addr)
+		pr_cont("ADDR %llx ", m->addr);
+	if (m->misc)
+		pr_cont("MISC %llx ", m->misc);
+
+	pr_cont("\n");
+	/*
+	 * Note this output is parsed by external tools and old fields
+	 * should not be changed.
+	 */
+	pr_emerg(HW_ERR "PROCESSOR %u:%x TIME %llu SOCKET %u APIC %x microcode %x\n",
+		m->cpuvendor, m->cpuid, m->time, m->socketid, m->apicid,
+		cpu_data(m->extcpu).microcode);
+
+	/*
+	 * Print out human-readable details about the MCE error,
+	 * (if the CPU has an implementation for that)
+	 */
+	ret = atomic_notifier_call_chain(&x86_mce_decoder_chain, 0, m);
+	if (ret == NOTIFY_STOP)
+		return;
+
+	pr_emerg_ratelimited(HW_ERR "Run the above through 'mcelog --ascii'\n");
+}
+
+#define PANIC_TIMEOUT 5 /* 5 seconds */
+
+static atomic_t mce_panicked;
+
+static int fake_panic;
+static atomic_t mce_fake_panicked;
+
+/* 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 = mca_cfg.panic_timeout;
+	panic("Panicing machine check CPU died");
+}
+
+static void mce_panic(const char *msg, struct mce *final, char *exp)
+{
+	int i, apei_err = 0;
+
+	if (!fake_panic) {
+		/*
+		 * Make sure only one CPU runs in machine check panic
+		 */
+		if (atomic_inc_return(&mce_panicked) > 1)
+			wait_for_panic();
+		barrier();
+
+		bust_spinlocks(1);
+		console_verbose();
+	} else {
+		/* Don't log too much for fake panic */
+		if (atomic_inc_return(&mce_fake_panicked) > 1)
+			return;
+	}
+	/* 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);
+			if (!apei_err)
+				apei_err = apei_write_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 (!apei_err)
+				apei_err = apei_write_mce(m);
+		}
+	}
+	if (final) {
+		print_mce(final);
+		if (!apei_err)
+			apei_err = apei_write_mce(final);
+	}
+	if (cpu_missing)
+		pr_emerg(HW_ERR "Some CPUs didn't answer in synchronization\n");
+	if (exp)
+		pr_emerg(HW_ERR "Machine check: %s\n", exp);
+	if (!fake_panic) {
+		if (panic_timeout == 0)
+			panic_timeout = mca_cfg.panic_timeout;
+		panic(msg);
+	} else
+		pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg);
+}
+
+/* Support code for software error injection */
+
+static int msr_to_offset(u32 msr)
+{
+	unsigned bank = __this_cpu_read(injectm.bank);
+
+	if (msr == mca_cfg.rip_msr)
+		return offsetof(struct mce, ip);
+	if (msr == MSR_IA32_MCx_STATUS(bank))
+		return offsetof(struct mce, status);
+	if (msr == MSR_IA32_MCx_ADDR(bank))
+		return offsetof(struct mce, addr);
+	if (msr == MSR_IA32_MCx_MISC(bank))
+		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 (__this_cpu_read(injectm.finished)) {
+		int offset = msr_to_offset(msr);
+
+		if (offset < 0)
+			return 0;
+		return *(u64 *)((char *)this_cpu_ptr(&injectm) + offset);
+	}
+
+	if (rdmsrl_safe(msr, &v)) {
+		WARN_ONCE(1, "mce: Unable to read msr %d!\n", msr);
+		/*
+		 * Return zero in case the access faulted. This should
+		 * not happen normally but can happen if the CPU does
+		 * something weird, or if the code is buggy.
+		 */
+		v = 0;
+	}
+
+	return v;
+}
+
+static void mce_wrmsrl(u32 msr, u64 v)
+{
+	if (__this_cpu_read(injectm.finished)) {
+		int offset = msr_to_offset(msr);
+
+		if (offset >= 0)
+			*(u64 *)((char *)this_cpu_ptr(&injectm) + offset) = v;
+		return;
+	}
+	wrmsrl(msr, v);
+}
+
+/*
+ * Collect all global (w.r.t. this processor) status about this machine
+ * check into our "mce" struct so that we can use it later to assess
+ * the severity of the problem as we read per-bank specific details.
+ */
+static inline void mce_gather_info(struct mce *m, struct pt_regs *regs)
+{
+	mce_setup(m);
+
+	m->mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
+	if (regs) {
+		/*
+		 * Get the address of the instruction at the time of
+		 * the machine check error.
+		 */
+		if (m->mcgstatus & (MCG_STATUS_RIPV|MCG_STATUS_EIPV)) {
+			m->ip = regs->ip;
+			m->cs = regs->cs;
+
+			/*
+			 * When in VM86 mode make the cs look like ring 3
+			 * always. This is a lie, but it's better than passing
+			 * the additional vm86 bit around everywhere.
+			 */
+			if (v8086_mode(regs))
+				m->cs |= 3;
+		}
+		/* Use accurate RIP reporting if available. */
+		if (mca_cfg.rip_msr)
+			m->ip = mce_rdmsrl(mca_cfg.rip_msr);
+	}
+}
+
+/*
+ * 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 = this_cpu_ptr(&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 = this_cpu_ptr(&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 = this_cpu_ptr(&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 (mca_cfg.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())
+		schedule_work(this_cpu_ptr(&mce_work));
+}
+
+static DEFINE_PER_CPU(struct irq_work, mce_irq_work);
+
+static void mce_irq_work_cb(struct irq_work *entry)
+{
+	mce_notify_irq();
+	mce_schedule_work();
+}
+
+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;
+	}
+
+	irq_work_queue(this_cpu_ptr(&mce_irq_work));
+}
+
+/*
+ * Read ADDR and MISC registers.
+ */
+static void mce_read_aux(struct mce *m, int i)
+{
+	if (m->status & MCI_STATUS_MISCV)
+		m->misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i));
+	if (m->status & MCI_STATUS_ADDRV) {
+		m->addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i));
+
+		/*
+		 * Mask the reported address by the reported granularity.
+		 */
+		if (mca_cfg.ser && (m->status & MCI_STATUS_MISCV)) {
+			u8 shift = MCI_MISC_ADDR_LSB(m->misc);
+			m->addr >>= shift;
+			m->addr <<= shift;
+		}
+	}
+}
+
+static bool memory_error(struct mce *m)
+{
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
+	if (c->x86_vendor == X86_VENDOR_AMD) {
+		/*
+		 * coming soon
+		 */
+		return false;
+	} else if (c->x86_vendor == X86_VENDOR_INTEL) {
+		/*
+		 * Intel SDM Volume 3B - 15.9.2 Compound Error Codes
+		 *
+		 * Bit 7 of the MCACOD field of IA32_MCi_STATUS is used for
+		 * indicating a memory error. Bit 8 is used for indicating a
+		 * cache hierarchy error. The combination of bit 2 and bit 3
+		 * is used for indicating a `generic' cache hierarchy error
+		 * But we can't just blindly check the above bits, because if
+		 * bit 11 is set, then it is a bus/interconnect error - and
+		 * either way the above bits just gives more detail on what
+		 * bus/interconnect error happened. Note that bit 12 can be
+		 * ignored, as it's the "filter" bit.
+		 */
+		return (m->status & 0xef80) == BIT(7) ||
+		       (m->status & 0xef00) == BIT(8) ||
+		       (m->status & 0xeffc) == 0xc;
+	}
+
+	return false;
+}
+
+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.
+ */
+bool machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
+{
+	bool error_logged = false;
+	struct mce m;
+	int severity;
+	int i;
+
+	this_cpu_inc(mce_poll_count);
+
+	mce_gather_info(&m, NULL);
+
+	for (i = 0; i < mca_cfg.banks; i++) {
+		if (!mce_banks[i].ctl || !test_bit(i, *b))
+			continue;
+
+		m.misc = 0;
+		m.addr = 0;
+		m.bank = i;
+		m.tsc = 0;
+
+		barrier();
+		m.status = mce_rdmsrl(MSR_IA32_MCx_STATUS(i));
+		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 & (mca_cfg.ser ? MCI_STATUS_S : MCI_STATUS_UC)))
+			continue;
+
+		mce_read_aux(&m, i);
+
+		if (!(flags & MCP_TIMESTAMP))
+			m.tsc = 0;
+
+		severity = mce_severity(&m, mca_cfg.tolerant, NULL, false);
+
+		/*
+		 * In the cases where we don't have a valid address after all,
+		 * do not add it into the ring buffer.
+		 */
+		if (severity == MCE_DEFERRED_SEVERITY && memory_error(&m)) {
+			if (m.status & MCI_STATUS_ADDRV) {
+				mce_ring_add(m.addr >> PAGE_SHIFT);
+				mce_schedule_work();
+			}
+		}
+
+		/*
+		 * Don't get the IP here because it's unlikely to
+		 * have anything to do with the actual error location.
+		 */
+		if (!(flags & MCP_DONTLOG) && !mca_cfg.dont_log_ce) {
+			error_logged = true;
+			mce_log(&m);
+		}
+
+		/*
+		 * Clear state for this bank.
+		 */
+		mce_wrmsrl(MSR_IA32_MCx_STATUS(i), 0);
+	}
+
+	/*
+	 * Don't clear MCG_STATUS here because it's only defined for
+	 * exceptions.
+	 */
+
+	sync_core();
+
+	return error_logged;
+}
+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, unsigned long *validp,
+			  struct pt_regs *regs)
+{
+	int i, ret = 0;
+	char *tmp;
+
+	for (i = 0; i < mca_cfg.banks; i++) {
+		m->status = mce_rdmsrl(MSR_IA32_MCx_STATUS(i));
+		if (m->status & MCI_STATUS_VAL) {
+			__set_bit(i, validp);
+			if (quirk_no_way_out)
+				quirk_no_way_out(i, m, regs);
+		}
+
+		if (mce_severity(m, mca_cfg.tolerant, &tmp, true) >= MCE_PANIC_SEVERITY) {
+			*msg = tmp;
+			ret = 1;
+		}
+	}
+	return ret;
+}
+
+/*
+ * 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, const char *msg)
+{
+	/*
+	 * 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_panicked))
+		wait_for_panic();
+	if (!mca_cfg.monarch_timeout)
+		goto out;
+	if ((s64)*t < SPINUNIT) {
+		if (mca_cfg.tolerant <= 1)
+			mce_panic(msg, 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 a 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),
+					    mca_cfg.tolerant,
+					    &nmsg, true);
+		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 && mca_cfg.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 (global_worst <= MCE_KEEP_SEVERITY && mca_cfg.tolerant < 3)
+		mce_panic("Fatal 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 cpus = num_online_cpus();
+	u64 timeout = (u64)mca_cfg.monarch_timeout * NSEC_PER_USEC;
+
+	if (!timeout)
+		return -1;
+
+	atomic_add(*no_way_out, &global_nwo);
+	/*
+	 * global_nwo should be updated before mce_callin
+	 */
+	smp_wmb();
+	order = atomic_inc_return(&mce_callin);
+
+	/*
+	 * Wait for everyone.
+	 */
+	while (atomic_read(&mce_callin) != cpus) {
+		if (mce_timed_out(&timeout,
+				  "Timeout: Not all CPUs entered broadcast exception handler")) {
+			atomic_set(&global_nwo, 0);
+			return -1;
+		}
+		ndelay(SPINUNIT);
+	}
+
+	/*
+	 * mce_callin should be read before global_nwo
+	 */
+	smp_rmb();
+
+	if (order == 1) {
+		/*
+		 * Monarch: Starts executing now, the others wait.
+		 */
+		atomic_set(&mce_executing, 1);
+	} else {
+		/*
+		 * Subject: 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,
+					  "Timeout: Subject CPUs unable to finish machine check processing")) {
+				atomic_set(&global_nwo, 0);
+				return -1;
+			}
+			ndelay(SPINUNIT);
+		}
+	}
+
+	/*
+	 * Cache the global no_way_out state.
+	 */
+	*no_way_out = atomic_read(&global_nwo);
+
+	return order;
+}
+
+/*
+ * 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)mca_cfg.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,
+					  "Timeout: Monarch CPU unable to finish machine check processing"))
+				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,
+					  "Timeout: Monarch CPU did not finish machine check processing"))
+				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 up to 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 (MCI_MISC_ADDR_LSB(m->misc) > PAGE_SHIFT)
+		return 0;
+	if (MCI_MISC_ADDR_MODE(m->misc) != MCI_MISC_ADDR_PHYS)
+		return 0;
+	return 1;
+}
+
+static void mce_clear_state(unsigned long *toclear)
+{
+	int i;
+
+	for (i = 0; i < mca_cfg.banks; i++) {
+		if (test_bit(i, toclear))
+			mce_wrmsrl(MSR_IA32_MCx_STATUS(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 mca_config *cfg = &mca_cfg;
+	struct mce m, *final;
+	enum ctx_state prev_state;
+	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 mca_cfg.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);
+	DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
+	char *msg = "Unknown";
+	u64 recover_paddr = ~0ull;
+	int flags = MF_ACTION_REQUIRED;
+
+	prev_state = ist_enter(regs);
+
+	this_cpu_inc(mce_exception_count);
+
+	if (!cfg->banks)
+		goto out;
+
+	mce_gather_info(&m, regs);
+
+	final = this_cpu_ptr(&mces_seen);
+	*final = m;
+
+	memset(valid_banks, 0, sizeof(valid_banks));
+	no_way_out = mce_no_way_out(&m, &msg, valid_banks, regs);
+
+	barrier();
+
+	/*
+	 * When no restart IP might need to kill or panic.
+	 * Assume the worst for now, but if we find the
+	 * severity is MCE_AR_SEVERITY we have other options.
+	 */
+	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.
+	 */
+	order = mce_start(&no_way_out);
+	for (i = 0; i < cfg->banks; i++) {
+		__clear_bit(i, toclear);
+		if (!test_bit(i, valid_banks))
+			continue;
+		if (!mce_banks[i].ctl)
+			continue;
+
+		m.misc = 0;
+		m.addr = 0;
+		m.bank = i;
+
+		m.status = mce_rdmsrl(MSR_IA32_MCx_STATUS(i));
+		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 & (cfg->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, LOCKDEP_NOW_UNRELIABLE);
+
+		severity = mce_severity(&m, cfg->tolerant, NULL, true);
+
+		/*
+		 * When machine check was for corrected/deferred handler don't
+		 * touch, unless we're panicing.
+		 */
+		if ((severity == MCE_KEEP_SEVERITY ||
+		     severity == MCE_UCNA_SEVERITY) && !no_way_out)
+			continue;
+		__set_bit(i, toclear);
+		if (severity == MCE_NO_SEVERITY) {
+			/*
+			 * Machine check event was not enabled. Clear, but
+			 * ignore.
+			 */
+			continue;
+		}
+
+		mce_read_aux(&m, i);
+
+		/*
+		 * 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 mca_cfg.tolerant == 0
+		 */
+		if (severity == MCE_AO_SEVERITY && mce_usable_address(&m))
+			mce_ring_add(m.addr >> PAGE_SHIFT);
+
+		mce_log(&m);
+
+		if (severity > worst) {
+			*final = m;
+			worst = severity;
+		}
+	}
+
+	/* mce_clear_state will clear *final, save locally for use later */
+	m = *final;
+
+	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;
+
+	/*
+	 * At insane "tolerant" levels we take no action. Otherwise
+	 * we only die if we have no other choice. For less serious
+	 * issues we try to recover, or limit damage to the current
+	 * process.
+	 */
+	if (cfg->tolerant < 3) {
+		if (no_way_out)
+			mce_panic("Fatal machine check on current CPU", &m, msg);
+		if (worst == MCE_AR_SEVERITY) {
+			recover_paddr = m.addr;
+			if (!(m.mcgstatus & MCG_STATUS_RIPV))
+				flags |= MF_MUST_KILL;
+		} else if (kill_it) {
+			force_sig(SIGBUS, current);
+		}
+	}
+
+	if (worst > 0)
+		mce_report_event(regs);
+	mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
+out:
+	sync_core();
+
+	if (recover_paddr == ~0ull)
+		goto done;
+
+	pr_err("Uncorrected hardware memory error in user-access at %llx",
+		 recover_paddr);
+	/*
+	 * We must call memory_failure() here even if the current process is
+	 * doomed. We still need to mark the page as poisoned and alert any
+	 * other users of the page.
+	 */
+	ist_begin_non_atomic(regs);
+	local_irq_enable();
+	if (memory_failure(recover_paddr >> PAGE_SHIFT, MCE_VECTOR, flags) < 0) {
+		pr_err("Memory error not recovered");
+		force_sig(SIGBUS, current);
+	}
+	local_irq_disable();
+	ist_end_non_atomic();
+done:
+	ist_exit(regs, prev_state);
+}
+EXPORT_SYMBOL_GPL(do_machine_check);
+
+#ifndef CONFIG_MEMORY_FAILURE
+int memory_failure(unsigned long pfn, int vector, int flags)
+{
+	/* mce_severity() should not hand us an ACTION_REQUIRED error */
+	BUG_ON(flags & MF_ACTION_REQUIRED);
+	pr_err("Uncorrected memory error in page 0x%lx ignored\n"
+	       "Rebuild kernel with CONFIG_MEMORY_FAILURE=y for smarter handling\n",
+	       pfn);
+
+	return 0;
+}
+#endif
+
+/*
+ * Action optional processing happens here (picking up
+ * from the list of faulting pages that do_machine_check()
+ * placed into the "ring").
+ */
+static void mce_process_work(struct work_struct *dummy)
+{
+	unsigned long pfn;
+
+	while (mce_ring_get(&pfn))
+		memory_failure(pfn, MCE_VECTOR, 0);
+}
+
+#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 unsigned long check_interval = INITIAL_CHECK_INTERVAL;
+
+static DEFINE_PER_CPU(unsigned long, mce_next_interval); /* in jiffies */
+static DEFINE_PER_CPU(struct timer_list, mce_timer);
+
+static unsigned long mce_adjust_timer_default(unsigned long interval)
+{
+	return interval;
+}
+
+static unsigned long (*mce_adjust_timer)(unsigned long interval) = mce_adjust_timer_default;
+
+static void __restart_timer(struct timer_list *t, unsigned long interval)
+{
+	unsigned long when = jiffies + interval;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	if (timer_pending(t)) {
+		if (time_before(when, t->expires))
+			mod_timer_pinned(t, when);
+	} else {
+		t->expires = round_jiffies(when);
+		add_timer_on(t, smp_processor_id());
+	}
+
+	local_irq_restore(flags);
+}
+
+static void mce_timer_fn(unsigned long data)
+{
+	struct timer_list *t = this_cpu_ptr(&mce_timer);
+	int cpu = smp_processor_id();
+	unsigned long iv;
+
+	WARN_ON(cpu != data);
+
+	iv = __this_cpu_read(mce_next_interval);
+
+	if (mce_available(this_cpu_ptr(&cpu_info))) {
+		machine_check_poll(MCP_TIMESTAMP, this_cpu_ptr(&mce_poll_banks));
+
+		if (mce_intel_cmci_poll()) {
+			iv = mce_adjust_timer(iv);
+			goto done;
+		}
+	}
+
+	/*
+	 * Alert userspace if needed. If we logged an MCE, reduce the polling
+	 * interval, otherwise increase the polling interval.
+	 */
+	if (mce_notify_irq())
+		iv = max(iv / 2, (unsigned long) HZ/100);
+	else
+		iv = min(iv * 2, round_jiffies_relative(check_interval * HZ));
+
+done:
+	__this_cpu_write(mce_next_interval, iv);
+	__restart_timer(t, iv);
+}
+
+/*
+ * Ensure that the timer is firing in @interval from now.
+ */
+void mce_timer_kick(unsigned long interval)
+{
+	struct timer_list *t = this_cpu_ptr(&mce_timer);
+	unsigned long iv = __this_cpu_read(mce_next_interval);
+
+	__restart_timer(t, interval);
+
+	if (interval < iv)
+		__this_cpu_write(mce_next_interval, interval);
+}
+
+/* Must not be called in IRQ context where del_timer_sync() can deadlock */
+static void mce_timer_delete_all(void)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		del_timer_sync(&per_cpu(mce_timer, cpu));
+}
+
+static void mce_do_trigger(struct work_struct *work)
+{
+	call_usermodehelper(mce_helper, mce_helper_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);
+
+	if (test_and_clear_bit(0, &mce_need_notify)) {
+		/* wake processes polling /dev/mcelog */
+		wake_up_interruptible(&mce_chrdev_wait);
+
+		if (mce_helper[0])
+			schedule_work(&mce_trigger_work);
+
+		if (__ratelimit(&ratelimit))
+			pr_info(HW_ERR "Machine check events logged\n");
+
+		return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mce_notify_irq);
+
+static int __mcheck_cpu_mce_banks_init(void)
+{
+	int i;
+	u8 num_banks = mca_cfg.banks;
+
+	mce_banks = kzalloc(num_banks * sizeof(struct mce_bank), GFP_KERNEL);
+	if (!mce_banks)
+		return -ENOMEM;
+
+	for (i = 0; i < num_banks; i++) {
+		struct mce_bank *b = &mce_banks[i];
+
+		b->ctl = -1ULL;
+		b->init = 1;
+	}
+	return 0;
+}
+
+/*
+ * Initialize Machine Checks for a CPU.
+ */
+static int __mcheck_cpu_cap_init(void)
+{
+	unsigned b;
+	u64 cap;
+
+	rdmsrl(MSR_IA32_MCG_CAP, cap);
+
+	b = cap & MCG_BANKCNT_MASK;
+	if (!mca_cfg.banks)
+		pr_info("CPU supports %d MCE banks\n", b);
+
+	if (b > MAX_NR_BANKS) {
+		pr_warn("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(mca_cfg.banks != 0 && b != mca_cfg.banks);
+	mca_cfg.banks = b;
+
+	if (!mce_banks) {
+		int err = __mcheck_cpu_mce_banks_init();
+
+		if (err)
+			return err;
+	}
+
+	/* Use accurate RIP reporting if available. */
+	if ((cap & MCG_EXT_P) && MCG_EXT_CNT(cap) >= 9)
+		mca_cfg.rip_msr = MSR_IA32_MCG_EIP;
+
+	if (cap & MCG_SER_P)
+		mca_cfg.ser = true;
+
+	return 0;
+}
+
+static void __mcheck_cpu_init_generic(void)
+{
+	enum mcp_flags m_fl = 0;
+	mce_banks_t all_banks;
+	u64 cap;
+	int i;
+
+	if (!mca_cfg.bootlog)
+		m_fl = MCP_DONTLOG;
+
+	/*
+	 * Log the machine checks left over from the previous reset.
+	 */
+	bitmap_fill(all_banks, MAX_NR_BANKS);
+	machine_check_poll(MCP_UC | m_fl, &all_banks);
+
+	cr4_set_bits(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 < mca_cfg.banks; i++) {
+		struct mce_bank *b = &mce_banks[i];
+
+		if (!b->init)
+			continue;
+		wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl);
+		wrmsrl(MSR_IA32_MCx_STATUS(i), 0);
+	}
+}
+
+/*
+ * During IFU recovery Sandy Bridge -EP4S processors set the RIPV and
+ * EIPV bits in MCG_STATUS to zero on the affected logical processor (SDM
+ * Vol 3B Table 15-20). But this confuses both the code that determines
+ * whether the machine check occurred in kernel or user mode, and also
+ * the severity assessment code. Pretend that EIPV was set, and take the
+ * ip/cs values from the pt_regs that mce_gather_info() ignored earlier.
+ */
+static void quirk_sandybridge_ifu(int bank, struct mce *m, struct pt_regs *regs)
+{
+	if (bank != 0)
+		return;
+	if ((m->mcgstatus & (MCG_STATUS_EIPV|MCG_STATUS_RIPV)) != 0)
+		return;
+	if ((m->status & (MCI_STATUS_OVER|MCI_STATUS_UC|
+		          MCI_STATUS_EN|MCI_STATUS_MISCV|MCI_STATUS_ADDRV|
+			  MCI_STATUS_PCC|MCI_STATUS_S|MCI_STATUS_AR|
+			  MCACOD)) !=
+			 (MCI_STATUS_UC|MCI_STATUS_EN|
+			  MCI_STATUS_MISCV|MCI_STATUS_ADDRV|MCI_STATUS_S|
+			  MCI_STATUS_AR|MCACOD_INSTR))
+		return;
+
+	m->mcgstatus |= MCG_STATUS_EIPV;
+	m->ip = regs->ip;
+	m->cs = regs->cs;
+}
+
+/* Add per CPU specific workarounds here */
+static int __mcheck_cpu_apply_quirks(struct cpuinfo_x86 *c)
+{
+	struct mca_config *cfg = &mca_cfg;
+
+	if (c->x86_vendor == X86_VENDOR_UNKNOWN) {
+		pr_info("unknown CPU type - not enabling MCE support\n");
+		return -EOPNOTSUPP;
+	}
+
+	/* This should be disabled by the BIOS, but isn't always */
+	if (c->x86_vendor == X86_VENDOR_AMD) {
+		if (c->x86 == 15 && cfg->banks > 4) {
+			/*
+			 * disable GART TBL walk error reporting, which
+			 * trips off incorrectly with the IOMMU & 3ware
+			 * & Cerberus:
+			 */
+			clear_bit(10, (unsigned long *)&mce_banks[4].ctl);
+		}
+		if (c->x86 <= 17 && cfg->bootlog < 0) {
+			/*
+			 * Lots of broken BIOS around that don't clear them
+			 * by default and leave crap in there. Don't log:
+			 */
+			cfg->bootlog = 0;
+		}
+		/*
+		 * Various K7s with broken bank 0 around. Always disable
+		 * by default.
+		 */
+		if (c->x86 == 6 && cfg->banks > 0)
+			mce_banks[0].ctl = 0;
+
+		/*
+		 * overflow_recov is supported for F15h Models 00h-0fh
+		 * even though we don't have a CPUID bit for it.
+		 */
+		if (c->x86 == 0x15 && c->x86_model <= 0xf)
+			mce_flags.overflow_recov = 1;
+
+		/*
+		 * Turn off MC4_MISC thresholding banks on those models since
+		 * they're not supported there.
+		 */
+		if (c->x86 == 0x15 &&
+		    (c->x86_model >= 0x10 && c->x86_model <= 0x1f)) {
+			int i;
+			u64 hwcr;
+			bool need_toggle;
+			u32 msrs[] = {
+				0x00000413, /* MC4_MISC0 */
+				0xc0000408, /* MC4_MISC1 */
+			};
+
+			rdmsrl(MSR_K7_HWCR, hwcr);
+
+			/* McStatusWrEn has to be set */
+			need_toggle = !(hwcr & BIT(18));
+
+			if (need_toggle)
+				wrmsrl(MSR_K7_HWCR, hwcr | BIT(18));
+
+			/* Clear CntP bit safely */
+			for (i = 0; i < ARRAY_SIZE(msrs); i++)
+				msr_clear_bit(msrs[i], 62);
+
+			/* restore old settings */
+			if (need_toggle)
+				wrmsrl(MSR_K7_HWCR, hwcr);
+		}
+	}
+
+	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 && cfg->banks > 0)
+			mce_banks[0].init = 0;
+
+		/*
+		 * 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)) &&
+			cfg->monarch_timeout < 0)
+			cfg->monarch_timeout = USEC_PER_SEC;
+
+		/*
+		 * There are also broken BIOSes on some Pentium M and
+		 * earlier systems:
+		 */
+		if (c->x86 == 6 && c->x86_model <= 13 && cfg->bootlog < 0)
+			cfg->bootlog = 0;
+
+		if (c->x86 == 6 && c->x86_model == 45)
+			quirk_no_way_out = quirk_sandybridge_ifu;
+	}
+	if (cfg->monarch_timeout < 0)
+		cfg->monarch_timeout = 0;
+	if (cfg->bootlog != 0)
+		cfg->panic_timeout = 30;
+
+	return 0;
+}
+
+static int __mcheck_cpu_ancient_init(struct cpuinfo_x86 *c)
+{
+	if (c->x86 != 5)
+		return 0;
+
+	switch (c->x86_vendor) {
+	case X86_VENDOR_INTEL:
+		intel_p5_mcheck_init(c);
+		return 1;
+		break;
+	case X86_VENDOR_CENTAUR:
+		winchip_mcheck_init(c);
+		return 1;
+		break;
+	}
+
+	return 0;
+}
+
+static void __mcheck_cpu_init_vendor(struct cpuinfo_x86 *c)
+{
+	switch (c->x86_vendor) {
+	case X86_VENDOR_INTEL:
+		mce_intel_feature_init(c);
+		mce_adjust_timer = cmci_intel_adjust_timer;
+		break;
+	case X86_VENDOR_AMD:
+		mce_amd_feature_init(c);
+		mce_flags.overflow_recov = cpuid_ebx(0x80000007) & 0x1;
+		break;
+	default:
+		break;
+	}
+}
+
+static void mce_start_timer(unsigned int cpu, struct timer_list *t)
+{
+	unsigned long iv = check_interval * HZ;
+
+	if (mca_cfg.ignore_ce || !iv)
+		return;
+
+	per_cpu(mce_next_interval, cpu) = iv;
+
+	t->expires = round_jiffies(jiffies + iv);
+	add_timer_on(t, cpu);
+}
+
+static void __mcheck_cpu_init_timer(void)
+{
+	struct timer_list *t = this_cpu_ptr(&mce_timer);
+	unsigned int cpu = smp_processor_id();
+
+	setup_timer(t, mce_timer_fn, cpu);
+	mce_start_timer(cpu, t);
+}
+
+/* Handle unconfigured int18 (should never happen) */
+static void unexpected_machine_check(struct pt_regs *regs, long error_code)
+{
+	pr_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;
+
+/*
+ * Called for each booted CPU to set up machine checks.
+ * Must be called with preempt off:
+ */
+void mcheck_cpu_init(struct cpuinfo_x86 *c)
+{
+	if (mca_cfg.disabled)
+		return;
+
+	if (__mcheck_cpu_ancient_init(c))
+		return;
+
+	if (!mce_available(c))
+		return;
+
+	if (__mcheck_cpu_cap_init() < 0 || __mcheck_cpu_apply_quirks(c) < 0) {
+		mca_cfg.disabled = true;
+		return;
+	}
+
+	machine_check_vector = do_machine_check;
+
+	__mcheck_cpu_init_generic();
+	__mcheck_cpu_init_vendor(c);
+	__mcheck_cpu_init_timer();
+	INIT_WORK(this_cpu_ptr(&mce_work), mce_process_work);
+	init_irq_work(this_cpu_ptr(&mce_irq_work), &mce_irq_work_cb);
+}
+
+/*
+ * mce_chrdev: Character device /dev/mcelog to read and clear the MCE log.
+ */
+
+static DEFINE_SPINLOCK(mce_chrdev_state_lock);
+static int mce_chrdev_open_count;	/* #times opened */
+static int mce_chrdev_open_exclu;	/* already open exclusive? */
+
+static int mce_chrdev_open(struct inode *inode, struct file *file)
+{
+	spin_lock(&mce_chrdev_state_lock);
+
+	if (mce_chrdev_open_exclu ||
+	    (mce_chrdev_open_count && (file->f_flags & O_EXCL))) {
+		spin_unlock(&mce_chrdev_state_lock);
+
+		return -EBUSY;
+	}
+
+	if (file->f_flags & O_EXCL)
+		mce_chrdev_open_exclu = 1;
+	mce_chrdev_open_count++;
+
+	spin_unlock(&mce_chrdev_state_lock);
+
+	return nonseekable_open(inode, file);
+}
+
+static int mce_chrdev_release(struct inode *inode, struct file *file)
+{
+	spin_lock(&mce_chrdev_state_lock);
+
+	mce_chrdev_open_count--;
+	mce_chrdev_open_exclu = 0;
+
+	spin_unlock(&mce_chrdev_state_lock);
+
+	return 0;
+}
+
+static void collect_tscs(void *data)
+{
+	unsigned long *cpu_tsc = (unsigned long *)data;
+
+	rdtscll(cpu_tsc[smp_processor_id()]);
+}
+
+static int mce_apei_read_done;
+
+/* Collect MCE record of previous boot in persistent storage via APEI ERST. */
+static int __mce_read_apei(char __user **ubuf, size_t usize)
+{
+	int rc;
+	u64 record_id;
+	struct mce m;
+
+	if (usize < sizeof(struct mce))
+		return -EINVAL;
+
+	rc = apei_read_mce(&m, &record_id);
+	/* Error or no more MCE record */
+	if (rc <= 0) {
+		mce_apei_read_done = 1;
+		/*
+		 * When ERST is disabled, mce_chrdev_read() should return
+		 * "no record" instead of "no device."
+		 */
+		if (rc == -ENODEV)
+			return 0;
+		return rc;
+	}
+	rc = -EFAULT;
+	if (copy_to_user(*ubuf, &m, sizeof(struct mce)))
+		return rc;
+	/*
+	 * In fact, we should have cleared the record after that has
+	 * been flushed to the disk or sent to network in
+	 * /sbin/mcelog, but we have no interface to support that now,
+	 * so just clear it to avoid duplication.
+	 */
+	rc = apei_clear_mce(record_id);
+	if (rc) {
+		mce_apei_read_done = 1;
+		return rc;
+	}
+	*ubuf += sizeof(struct mce);
+
+	return 0;
+}
+
+static ssize_t mce_chrdev_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_chrdev_read_mutex);
+
+	if (!mce_apei_read_done) {
+		err = __mce_read_apei(&buf, usize);
+		if (err || buf != ubuf)
+			goto out;
+	}
+
+	next = rcu_dereference_check_mce(mcelog.next);
+
+	/* Only supports full reads right now */
+	err = -EINVAL;
+	if (*off != 0 || usize < MCE_LOG_LEN*sizeof(struct mce))
+		goto out;
+
+	err = 0;
+	prev = 0;
+	do {
+		for (i = prev; i < next; i++) {
+			unsigned long start = jiffies;
+			struct mce *m = &mcelog.entry[i];
+
+			while (!m->finished) {
+				if (time_after_eq(jiffies, start + 2)) {
+					memset(m, 0, sizeof(*m));
+					goto timeout;
+				}
+				cpu_relax();
+			}
+			smp_rmb();
+			err |= copy_to_user(buf, m, sizeof(*m));
+			buf += sizeof(*m);
+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++) {
+		struct mce *m = &mcelog.entry[i];
+
+		if (m->finished && m->tsc < cpu_tsc[m->cpu]) {
+			err |= copy_to_user(buf, m, sizeof(*m));
+			smp_rmb();
+			buf += sizeof(*m);
+			memset(m, 0, sizeof(*m));
+		}
+	}
+
+	if (err)
+		err = -EFAULT;
+
+out:
+	mutex_unlock(&mce_chrdev_read_mutex);
+	kfree(cpu_tsc);
+
+	return err ? err : buf - ubuf;
+}
+
+static unsigned int mce_chrdev_poll(struct file *file, poll_table *wait)
+{
+	poll_wait(file, &mce_chrdev_wait, wait);
+	if (rcu_access_index(mcelog.next))
+		return POLLIN | POLLRDNORM;
+	if (!mce_apei_read_done && apei_check_mce())
+		return POLLIN | POLLRDNORM;
+	return 0;
+}
+
+static long mce_chrdev_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;
+	}
+}
+
+static ssize_t (*mce_write)(struct file *filp, const char __user *ubuf,
+			    size_t usize, loff_t *off);
+
+void register_mce_write_callback(ssize_t (*fn)(struct file *filp,
+			     const char __user *ubuf,
+			     size_t usize, loff_t *off))
+{
+	mce_write = fn;
+}
+EXPORT_SYMBOL_GPL(register_mce_write_callback);
+
+ssize_t mce_chrdev_write(struct file *filp, const char __user *ubuf,
+			 size_t usize, loff_t *off)
+{
+	if (mce_write)
+		return mce_write(filp, ubuf, usize, off);
+	else
+		return -EINVAL;
+}
+
+static const struct file_operations mce_chrdev_ops = {
+	.open			= mce_chrdev_open,
+	.release		= mce_chrdev_release,
+	.read			= mce_chrdev_read,
+	.write			= mce_chrdev_write,
+	.poll			= mce_chrdev_poll,
+	.unlocked_ioctl		= mce_chrdev_ioctl,
+	.llseek			= no_llseek,
+};
+
+static struct miscdevice mce_chrdev_device = {
+	MISC_MCELOG_MINOR,
+	"mcelog",
+	&mce_chrdev_ops,
+};
+
+static void __mce_disable_bank(void *arg)
+{
+	int bank = *((int *)arg);
+	__clear_bit(bank, this_cpu_ptr(mce_poll_banks));
+	cmci_disable_bank(bank);
+}
+
+void mce_disable_bank(int bank)
+{
+	if (bank >= mca_cfg.banks) {
+		pr_warn(FW_BUG
+			"Ignoring request to disable invalid MCA bank %d.\n",
+			bank);
+		return;
+	}
+	set_bit(bank, mce_banks_ce_disabled);
+	on_each_cpu(__mce_disable_bank, &bank, 1);
+}
+
+/*
+ * 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.
+ * mce=bios_cmci_threshold Don't program the CMCI threshold
+ */
+static int __init mcheck_enable(char *str)
+{
+	struct mca_config *cfg = &mca_cfg;
+
+	if (*str == 0) {
+		enable_p5_mce();
+		return 1;
+	}
+	if (*str == '=')
+		str++;
+	if (!strcmp(str, "off"))
+		cfg->disabled = true;
+	else if (!strcmp(str, "no_cmci"))
+		cfg->cmci_disabled = true;
+	else if (!strcmp(str, "dont_log_ce"))
+		cfg->dont_log_ce = true;
+	else if (!strcmp(str, "ignore_ce"))
+		cfg->ignore_ce = true;
+	else if (!strcmp(str, "bootlog") || !strcmp(str, "nobootlog"))
+		cfg->bootlog = (str[0] == 'b');
+	else if (!strcmp(str, "bios_cmci_threshold"))
+		cfg->bios_cmci_threshold = true;
+	else if (isdigit(str[0])) {
+		get_option(&str, &(cfg->tolerant));
+		if (*str == ',') {
+			++str;
+			get_option(&str, &(cfg->monarch_timeout));
+		}
+	} else {
+		pr_info("mce argument %s ignored. Please use /sys\n", str);
+		return 0;
+	}
+	return 1;
+}
+__setup("mce", mcheck_enable);
+
+int __init mcheck_init(void)
+{
+	mcheck_intel_therm_init();
+	mcheck_vendor_init_severity();
+
+	return 0;
+}
+
+/*
+ * mce_syscore: PM support
+ */
+
+/*
+ * Disable machine checks on suspend and shutdown. We can't really handle
+ * them later.
+ */
+static int mce_disable_error_reporting(void)
+{
+	int i;
+
+	for (i = 0; i < mca_cfg.banks; i++) {
+		struct mce_bank *b = &mce_banks[i];
+
+		if (b->init)
+			wrmsrl(MSR_IA32_MCx_CTL(i), 0);
+	}
+	return 0;
+}
+
+static int mce_syscore_suspend(void)
+{
+	return mce_disable_error_reporting();
+}
+
+static void mce_syscore_shutdown(void)
+{
+	mce_disable_error_reporting();
+}
+
+/*
+ * 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 void mce_syscore_resume(void)
+{
+	__mcheck_cpu_init_generic();
+	__mcheck_cpu_init_vendor(raw_cpu_ptr(&cpu_info));
+}
+
+static struct syscore_ops mce_syscore_ops = {
+	.suspend	= mce_syscore_suspend,
+	.shutdown	= mce_syscore_shutdown,
+	.resume		= mce_syscore_resume,
+};
+
+/*
+ * mce_device: Sysfs support
+ */
+
+static void mce_cpu_restart(void *data)
+{
+	if (!mce_available(raw_cpu_ptr(&cpu_info)))
+		return;
+	__mcheck_cpu_init_generic();
+	__mcheck_cpu_init_timer();
+}
+
+/* Reinit MCEs after user configuration changes */
+static void mce_restart(void)
+{
+	mce_timer_delete_all();
+	on_each_cpu(mce_cpu_restart, NULL, 1);
+}
+
+/* Toggle features for corrected errors */
+static void mce_disable_cmci(void *data)
+{
+	if (!mce_available(raw_cpu_ptr(&cpu_info)))
+		return;
+	cmci_clear();
+}
+
+static void mce_enable_ce(void *all)
+{
+	if (!mce_available(raw_cpu_ptr(&cpu_info)))
+		return;
+	cmci_reenable();
+	cmci_recheck();
+	if (all)
+		__mcheck_cpu_init_timer();
+}
+
+static struct bus_type mce_subsys = {
+	.name		= "machinecheck",
+	.dev_name	= "machinecheck",
+};
+
+DEFINE_PER_CPU(struct device *, mce_device);
+
+void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu);
+
+static inline struct mce_bank *attr_to_bank(struct device_attribute *attr)
+{
+	return container_of(attr, struct mce_bank, attr);
+}
+
+static ssize_t show_bank(struct device *s, struct device_attribute *attr,
+			 char *buf)
+{
+	return sprintf(buf, "%llx\n", attr_to_bank(attr)->ctl);
+}
+
+static ssize_t set_bank(struct device *s, struct device_attribute *attr,
+			const char *buf, size_t size)
+{
+	u64 new;
+
+	if (kstrtou64(buf, 0, &new) < 0)
+		return -EINVAL;
+
+	attr_to_bank(attr)->ctl = new;
+	mce_restart();
+
+	return size;
+}
+
+static ssize_t
+show_trigger(struct device *s, struct device_attribute *attr, char *buf)
+{
+	strcpy(buf, mce_helper);
+	strcat(buf, "\n");
+	return strlen(mce_helper) + 1;
+}
+
+static ssize_t set_trigger(struct device *s, struct device_attribute *attr,
+				const char *buf, size_t siz)
+{
+	char *p;
+
+	strncpy(mce_helper, buf, sizeof(mce_helper));
+	mce_helper[sizeof(mce_helper)-1] = 0;
+	p = strchr(mce_helper, '\n');
+
+	if (p)
+		*p = 0;
+
+	return strlen(mce_helper) + !!p;
+}
+
+static ssize_t set_ignore_ce(struct device *s,
+			     struct device_attribute *attr,
+			     const char *buf, size_t size)
+{
+	u64 new;
+
+	if (kstrtou64(buf, 0, &new) < 0)
+		return -EINVAL;
+
+	if (mca_cfg.ignore_ce ^ !!new) {
+		if (new) {
+			/* disable ce features */
+			mce_timer_delete_all();
+			on_each_cpu(mce_disable_cmci, NULL, 1);
+			mca_cfg.ignore_ce = true;
+		} else {
+			/* enable ce features */
+			mca_cfg.ignore_ce = false;
+			on_each_cpu(mce_enable_ce, (void *)1, 1);
+		}
+	}
+	return size;
+}
+
+static ssize_t set_cmci_disabled(struct device *s,
+				 struct device_attribute *attr,
+				 const char *buf, size_t size)
+{
+	u64 new;
+
+	if (kstrtou64(buf, 0, &new) < 0)
+		return -EINVAL;
+
+	if (mca_cfg.cmci_disabled ^ !!new) {
+		if (new) {
+			/* disable cmci */
+			on_each_cpu(mce_disable_cmci, NULL, 1);
+			mca_cfg.cmci_disabled = true;
+		} else {
+			/* enable cmci */
+			mca_cfg.cmci_disabled = false;
+			on_each_cpu(mce_enable_ce, NULL, 1);
+		}
+	}
+	return size;
+}
+
+static ssize_t store_int_with_restart(struct device *s,
+				      struct device_attribute *attr,
+				      const char *buf, size_t size)
+{
+	ssize_t ret = device_store_int(s, attr, buf, size);
+	mce_restart();
+	return ret;
+}
+
+static DEVICE_ATTR(trigger, 0644, show_trigger, set_trigger);
+static DEVICE_INT_ATTR(tolerant, 0644, mca_cfg.tolerant);
+static DEVICE_INT_ATTR(monarch_timeout, 0644, mca_cfg.monarch_timeout);
+static DEVICE_BOOL_ATTR(dont_log_ce, 0644, mca_cfg.dont_log_ce);
+
+static struct dev_ext_attribute dev_attr_check_interval = {
+	__ATTR(check_interval, 0644, device_show_int, store_int_with_restart),
+	&check_interval
+};
+
+static struct dev_ext_attribute dev_attr_ignore_ce = {
+	__ATTR(ignore_ce, 0644, device_show_bool, set_ignore_ce),
+	&mca_cfg.ignore_ce
+};
+
+static struct dev_ext_attribute dev_attr_cmci_disabled = {
+	__ATTR(cmci_disabled, 0644, device_show_bool, set_cmci_disabled),
+	&mca_cfg.cmci_disabled
+};
+
+static struct device_attribute *mce_device_attrs[] = {
+	&dev_attr_tolerant.attr,
+	&dev_attr_check_interval.attr,
+	&dev_attr_trigger,
+	&dev_attr_monarch_timeout.attr,
+	&dev_attr_dont_log_ce.attr,
+	&dev_attr_ignore_ce.attr,
+	&dev_attr_cmci_disabled.attr,
+	NULL
+};
+
+static cpumask_var_t mce_device_initialized;
+
+static void mce_device_release(struct device *dev)
+{
+	kfree(dev);
+}
+
+/* Per cpu device init. All of the cpus still share the same ctrl bank: */
+static int mce_device_create(unsigned int cpu)
+{
+	struct device *dev;
+	int err;
+	int i, j;
+
+	if (!mce_available(&boot_cpu_data))
+		return -EIO;
+
+	dev = kzalloc(sizeof *dev, GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+	dev->id  = cpu;
+	dev->bus = &mce_subsys;
+	dev->release = &mce_device_release;
+
+	err = device_register(dev);
+	if (err) {
+		put_device(dev);
+		return err;
+	}
+
+	for (i = 0; mce_device_attrs[i]; i++) {
+		err = device_create_file(dev, mce_device_attrs[i]);
+		if (err)
+			goto error;
+	}
+	for (j = 0; j < mca_cfg.banks; j++) {
+		err = device_create_file(dev, &mce_banks[j].attr);
+		if (err)
+			goto error2;
+	}
+	cpumask_set_cpu(cpu, mce_device_initialized);
+	per_cpu(mce_device, cpu) = dev;
+
+	return 0;
+error2:
+	while (--j >= 0)
+		device_remove_file(dev, &mce_banks[j].attr);
+error:
+	while (--i >= 0)
+		device_remove_file(dev, mce_device_attrs[i]);
+
+	device_unregister(dev);
+
+	return err;
+}
+
+static void mce_device_remove(unsigned int cpu)
+{
+	struct device *dev = per_cpu(mce_device, cpu);
+	int i;
+
+	if (!cpumask_test_cpu(cpu, mce_device_initialized))
+		return;
+
+	for (i = 0; mce_device_attrs[i]; i++)
+		device_remove_file(dev, mce_device_attrs[i]);
+
+	for (i = 0; i < mca_cfg.banks; i++)
+		device_remove_file(dev, &mce_banks[i].attr);
+
+	device_unregister(dev);
+	cpumask_clear_cpu(cpu, mce_device_initialized);
+	per_cpu(mce_device, cpu) = NULL;
+}
+
+/* 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(raw_cpu_ptr(&cpu_info)))
+		return;
+
+	if (!(action & CPU_TASKS_FROZEN))
+		cmci_clear();
+	for (i = 0; i < mca_cfg.banks; i++) {
+		struct mce_bank *b = &mce_banks[i];
+
+		if (b->init)
+			wrmsrl(MSR_IA32_MCx_CTL(i), 0);
+	}
+}
+
+static void mce_reenable_cpu(void *h)
+{
+	unsigned long action = *(unsigned long *)h;
+	int i;
+
+	if (!mce_available(raw_cpu_ptr(&cpu_info)))
+		return;
+
+	if (!(action & CPU_TASKS_FROZEN))
+		cmci_reenable();
+	for (i = 0; i < mca_cfg.banks; i++) {
+		struct mce_bank *b = &mce_banks[i];
+
+		if (b->init)
+			wrmsrl(MSR_IA32_MCx_CTL(i), b->ctl);
+	}
+}
+
+/* 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;
+	struct timer_list *t = &per_cpu(mce_timer, cpu);
+
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_ONLINE:
+		mce_device_create(cpu);
+		if (threshold_cpu_callback)
+			threshold_cpu_callback(action, cpu);
+		break;
+	case CPU_DEAD:
+		if (threshold_cpu_callback)
+			threshold_cpu_callback(action, cpu);
+		mce_device_remove(cpu);
+		mce_intel_hcpu_update(cpu);
+
+		/* intentionally ignoring frozen here */
+		if (!(action & CPU_TASKS_FROZEN))
+			cmci_rediscover();
+		break;
+	case CPU_DOWN_PREPARE:
+		smp_call_function_single(cpu, mce_disable_cpu, &action, 1);
+		del_timer_sync(t);
+		break;
+	case CPU_DOWN_FAILED:
+		smp_call_function_single(cpu, mce_reenable_cpu, &action, 1);
+		mce_start_timer(cpu, t);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block mce_cpu_notifier = {
+	.notifier_call = mce_cpu_callback,
+};
+
+static __init void mce_init_banks(void)
+{
+	int i;
+
+	for (i = 0; i < mca_cfg.banks; i++) {
+		struct mce_bank *b = &mce_banks[i];
+		struct device_attribute *a = &b->attr;
+
+		sysfs_attr_init(&a->attr);
+		a->attr.name	= b->attrname;
+		snprintf(b->attrname, ATTR_LEN, "bank%d", i);
+
+		a->attr.mode	= 0644;
+		a->show		= show_bank;
+		a->store	= set_bank;
+	}
+}
+
+static __init int mcheck_init_device(void)
+{
+	int err;
+	int i = 0;
+
+	if (!mce_available(&boot_cpu_data)) {
+		err = -EIO;
+		goto err_out;
+	}
+
+	if (!zalloc_cpumask_var(&mce_device_initialized, GFP_KERNEL)) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	mce_init_banks();
+
+	err = subsys_system_register(&mce_subsys, NULL);
+	if (err)
+		goto err_out_mem;
+
+	cpu_notifier_register_begin();
+	for_each_online_cpu(i) {
+		err = mce_device_create(i);
+		if (err) {
+			/*
+			 * Register notifier anyway (and do not unreg it) so
+			 * that we don't leave undeleted timers, see notifier
+			 * callback above.
+			 */
+			__register_hotcpu_notifier(&mce_cpu_notifier);
+			cpu_notifier_register_done();
+			goto err_device_create;
+		}
+	}
+
+	__register_hotcpu_notifier(&mce_cpu_notifier);
+	cpu_notifier_register_done();
+
+	register_syscore_ops(&mce_syscore_ops);
+
+	/* register character device /dev/mcelog */
+	err = misc_register(&mce_chrdev_device);
+	if (err)
+		goto err_register;
+
+	return 0;
+
+err_register:
+	unregister_syscore_ops(&mce_syscore_ops);
+
+err_device_create:
+	/*
+	 * We didn't keep track of which devices were created above, but
+	 * even if we had, the set of online cpus might have changed.
+	 * Play safe and remove for every possible cpu, since
+	 * mce_device_remove() will do the right thing.
+	 */
+	for_each_possible_cpu(i)
+		mce_device_remove(i);
+
+err_out_mem:
+	free_cpumask_var(mce_device_initialized);
+
+err_out:
+	pr_err("Unable to init device /dev/mcelog (rc: %d)\n", err);
+
+	return err;
+}
+device_initcall_sync(mcheck_init_device);
+
+/*
+ * Old style boot options parsing. Only for compatibility.
+ */
+static int __init mcheck_disable(char *str)
+{
+	mca_cfg.disabled = true;
+	return 1;
+}
+__setup("nomce", mcheck_disable);
+
+#ifdef CONFIG_DEBUG_FS
+struct dentry *mce_get_debugfs_dir(void)
+{
+	static struct dentry *dmce;
+
+	if (!dmce)
+		dmce = debugfs_create_dir("mce", NULL);
+
+	return dmce;
+}
+
+static void mce_reset(void)
+{
+	cpu_missing = 0;
+	atomic_set(&mce_fake_panicked, 0);
+	atomic_set(&mce_executing, 0);
+	atomic_set(&mce_callin, 0);
+	atomic_set(&global_nwo, 0);
+}
+
+static int fake_panic_get(void *data, u64 *val)
+{
+	*val = fake_panic;
+	return 0;
+}
+
+static int fake_panic_set(void *data, u64 val)
+{
+	mce_reset();
+	fake_panic = val;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fake_panic_fops, fake_panic_get,
+			fake_panic_set, "%llu\n");
+
+static int __init mcheck_debugfs_init(void)
+{
+	struct dentry *dmce, *ffake_panic;
+
+	dmce = mce_get_debugfs_dir();
+	if (!dmce)
+		return -ENOMEM;
+	ffake_panic = debugfs_create_file("fake_panic", 0444, dmce, NULL,
+					  &fake_panic_fops);
+	if (!ffake_panic)
+		return -ENOMEM;
+
+	return 0;
+}
+late_initcall(mcheck_debugfs_init);
+#endif