i386: prepare shared kernel/nmi.c
authorThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:12:19 +0000 (11:12 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:12:19 +0000 (11:12 +0200)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/i386/kernel/Makefile
arch/i386/kernel/nmi.c [deleted file]
arch/i386/kernel/nmi_32.c [new file with mode: 0644]

index 2d22e13ecfd856e251538e5dd30bce3d6d97c45b..4967012119ae04b83b7cb160e64636a91a16b0fc 100644 (file)
@@ -22,7 +22,7 @@ obj-$(CONFIG_X86_SMP)         += smp_32.o smpboot.o tsc_sync.o
 obj-$(CONFIG_SMP)              += smpcommon.o
 obj-$(CONFIG_X86_TRAMPOLINE)   += trampoline.o
 obj-$(CONFIG_X86_MPPARSE)      += mpparse.o
-obj-$(CONFIG_X86_LOCAL_APIC)   += apic_32.o nmi.o
+obj-$(CONFIG_X86_LOCAL_APIC)   += apic_32.o nmi_32.o
 obj-$(CONFIG_X86_IO_APIC)      += io_apic_32.o
 obj-$(CONFIG_X86_REBOOTFIXUPS) += reboot_fixups.o
 obj-$(CONFIG_KEXEC)            += machine_kexec.o relocate_kernel_32.o crash_32.o
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
deleted file mode 100644 (file)
index c7227e2..0000000
+++ /dev/null
@@ -1,468 +0,0 @@
-/*
- *  linux/arch/i386/nmi.c
- *
- *  NMI watchdog support on APIC systems
- *
- *  Started by Ingo Molnar <mingo@redhat.com>
- *
- *  Fixes:
- *  Mikael Pettersson  : AMD K7 support for local APIC NMI watchdog.
- *  Mikael Pettersson  : Power Management for local APIC NMI watchdog.
- *  Mikael Pettersson  : Pentium 4 support for local APIC NMI watchdog.
- *  Pavel Machek and
- *  Mikael Pettersson  : PM converted to driver model. Disable/enable API.
- */
-
-#include <linux/delay.h>
-#include <linux/interrupt.h>
-#include <linux/module.h>
-#include <linux/nmi.h>
-#include <linux/sysdev.h>
-#include <linux/sysctl.h>
-#include <linux/percpu.h>
-#include <linux/kprobes.h>
-#include <linux/cpumask.h>
-#include <linux/kernel_stat.h>
-#include <linux/kdebug.h>
-
-#include <asm/smp.h>
-#include <asm/nmi.h>
-
-#include "mach_traps.h"
-
-int unknown_nmi_panic;
-int nmi_watchdog_enabled;
-
-static cpumask_t backtrace_mask = CPU_MASK_NONE;
-
-/* nmi_active:
- * >0: the lapic NMI watchdog is active, but can be disabled
- * <0: the lapic NMI watchdog has not been set up, and cannot
- *     be enabled
- *  0: the lapic NMI watchdog is disabled, but can be enabled
- */
-atomic_t nmi_active = ATOMIC_INIT(0);          /* oprofile uses this */
-
-unsigned int nmi_watchdog = NMI_DEFAULT;
-static unsigned int nmi_hz = HZ;
-
-static DEFINE_PER_CPU(short, wd_enabled);
-
-/* local prototypes */
-static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu);
-
-static int endflag __initdata = 0;
-
-#ifdef CONFIG_SMP
-/* The performance counters used by NMI_LOCAL_APIC don't trigger when
- * the CPU is idle. To make sure the NMI watchdog really ticks on all
- * CPUs during the test make them busy.
- */
-static __init void nmi_cpu_busy(void *data)
-{
-       local_irq_enable_in_hardirq();
-       /* Intentionally don't use cpu_relax here. This is
-          to make sure that the performance counter really ticks,
-          even if there is a simulator or similar that catches the
-          pause instruction. On a real HT machine this is fine because
-          all other CPUs are busy with "useless" delay loops and don't
-          care if they get somewhat less cycles. */
-       while (endflag == 0)
-               mb();
-}
-#endif
-
-static int __init check_nmi_watchdog(void)
-{
-       unsigned int *prev_nmi_count;
-       int cpu;
-
-       if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED))
-               return 0;
-
-       if (!atomic_read(&nmi_active))
-               return 0;
-
-       prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
-       if (!prev_nmi_count)
-               return -1;
-
-       printk(KERN_INFO "Testing NMI watchdog ... ");
-
-       if (nmi_watchdog == NMI_LOCAL_APIC)
-               smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
-
-       for_each_possible_cpu(cpu)
-               prev_nmi_count[cpu] = per_cpu(irq_stat, cpu).__nmi_count;
-       local_irq_enable();
-       mdelay((20*1000)/nmi_hz); // wait 20 ticks
-
-       for_each_possible_cpu(cpu) {
-#ifdef CONFIG_SMP
-               /* Check cpu_callin_map here because that is set
-                  after the timer is started. */
-               if (!cpu_isset(cpu, cpu_callin_map))
-                       continue;
-#endif
-               if (!per_cpu(wd_enabled, cpu))
-                       continue;
-               if (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {
-                       printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n",
-                               cpu,
-                               prev_nmi_count[cpu],
-                               nmi_count(cpu));
-                       per_cpu(wd_enabled, cpu) = 0;
-                       atomic_dec(&nmi_active);
-               }
-       }
-       endflag = 1;
-       if (!atomic_read(&nmi_active)) {
-               kfree(prev_nmi_count);
-               atomic_set(&nmi_active, -1);
-               return -1;
-       }
-       printk("OK.\n");
-
-       /* now that we know it works we can reduce NMI frequency to
-          something more reasonable; makes a difference in some configs */
-       if (nmi_watchdog == NMI_LOCAL_APIC)
-               nmi_hz = lapic_adjust_nmi_hz(1);
-
-       kfree(prev_nmi_count);
-       return 0;
-}
-/* This needs to happen later in boot so counters are working */
-late_initcall(check_nmi_watchdog);
-
-static int __init setup_nmi_watchdog(char *str)
-{
-       int nmi;
-
-       get_option(&str, &nmi);
-
-       if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE))
-               return 0;
-
-       nmi_watchdog = nmi;
-       return 1;
-}
-
-__setup("nmi_watchdog=", setup_nmi_watchdog);
-
-
-/* Suspend/resume support */
-
-#ifdef CONFIG_PM
-
-static int nmi_pm_active; /* nmi_active before suspend */
-
-static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
-{
-       /* only CPU0 goes here, other CPUs should be offline */
-       nmi_pm_active = atomic_read(&nmi_active);
-       stop_apic_nmi_watchdog(NULL);
-       BUG_ON(atomic_read(&nmi_active) != 0);
-       return 0;
-}
-
-static int lapic_nmi_resume(struct sys_device *dev)
-{
-       /* only CPU0 goes here, other CPUs should be offline */
-       if (nmi_pm_active > 0) {
-               setup_apic_nmi_watchdog(NULL);
-               touch_nmi_watchdog();
-       }
-       return 0;
-}
-
-
-static struct sysdev_class nmi_sysclass = {
-       set_kset_name("lapic_nmi"),
-       .resume         = lapic_nmi_resume,
-       .suspend        = lapic_nmi_suspend,
-};
-
-static struct sys_device device_lapic_nmi = {
-       .id     = 0,
-       .cls    = &nmi_sysclass,
-};
-
-static int __init init_lapic_nmi_sysfs(void)
-{
-       int error;
-
-       /* should really be a BUG_ON but b/c this is an
-        * init call, it just doesn't work.  -dcz
-        */
-       if (nmi_watchdog != NMI_LOCAL_APIC)
-               return 0;
-
-       if (atomic_read(&nmi_active) < 0)
-               return 0;
-
-       error = sysdev_class_register(&nmi_sysclass);
-       if (!error)
-               error = sysdev_register(&device_lapic_nmi);
-       return error;
-}
-/* must come after the local APIC's device_initcall() */
-late_initcall(init_lapic_nmi_sysfs);
-
-#endif /* CONFIG_PM */
-
-static void __acpi_nmi_enable(void *__unused)
-{
-       apic_write_around(APIC_LVT0, APIC_DM_NMI);
-}
-
-/*
- * Enable timer based NMIs on all CPUs:
- */
-void acpi_nmi_enable(void)
-{
-       if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
-               on_each_cpu(__acpi_nmi_enable, NULL, 0, 1);
-}
-
-static void __acpi_nmi_disable(void *__unused)
-{
-       apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
-}
-
-/*
- * Disable timer based NMIs on all CPUs:
- */
-void acpi_nmi_disable(void)
-{
-       if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
-               on_each_cpu(__acpi_nmi_disable, NULL, 0, 1);
-}
-
-void setup_apic_nmi_watchdog (void *unused)
-{
-       if (__get_cpu_var(wd_enabled))
-               return;
-
-       /* cheap hack to support suspend/resume */
-       /* if cpu0 is not active neither should the other cpus */
-       if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0))
-               return;
-
-       switch (nmi_watchdog) {
-       case NMI_LOCAL_APIC:
-               __get_cpu_var(wd_enabled) = 1; /* enable it before to avoid race with handler */
-               if (lapic_watchdog_init(nmi_hz) < 0) {
-                       __get_cpu_var(wd_enabled) = 0;
-                       return;
-               }
-               /* FALL THROUGH */
-       case NMI_IO_APIC:
-               __get_cpu_var(wd_enabled) = 1;
-               atomic_inc(&nmi_active);
-       }
-}
-
-void stop_apic_nmi_watchdog(void *unused)
-{
-       /* only support LOCAL and IO APICs for now */
-       if ((nmi_watchdog != NMI_LOCAL_APIC) &&
-           (nmi_watchdog != NMI_IO_APIC))
-               return;
-       if (__get_cpu_var(wd_enabled) == 0)
-               return;
-       if (nmi_watchdog == NMI_LOCAL_APIC)
-               lapic_watchdog_stop();
-       __get_cpu_var(wd_enabled) = 0;
-       atomic_dec(&nmi_active);
-}
-
-/*
- * the best way to detect whether a CPU has a 'hard lockup' problem
- * is to check it's local APIC timer IRQ counts. If they are not
- * changing then that CPU has some problem.
- *
- * as these watchdog NMI IRQs are generated on every CPU, we only
- * have to check the current processor.
- *
- * since NMIs don't listen to _any_ locks, we have to be extremely
- * careful not to rely on unsafe variables. The printk might lock
- * up though, so we have to break up any console locks first ...
- * [when there will be more tty-related locks, break them up
- *  here too!]
- */
-
-static unsigned int
-       last_irq_sums [NR_CPUS],
-       alert_counter [NR_CPUS];
-
-void touch_nmi_watchdog(void)
-{
-       if (nmi_watchdog > 0) {
-               unsigned cpu;
-
-               /*
-                * Just reset the alert counters, (other CPUs might be
-                * spinning on locks we hold):
-                */
-               for_each_present_cpu(cpu) {
-                       if (alert_counter[cpu])
-                               alert_counter[cpu] = 0;
-               }
-       }
-
-       /*
-        * Tickle the softlockup detector too:
-        */
-       touch_softlockup_watchdog();
-}
-EXPORT_SYMBOL(touch_nmi_watchdog);
-
-extern void die_nmi(struct pt_regs *, const char *msg);
-
-__kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
-{
-
-       /*
-        * Since current_thread_info()-> is always on the stack, and we
-        * always switch the stack NMI-atomically, it's safe to use
-        * smp_processor_id().
-        */
-       unsigned int sum;
-       int touched = 0;
-       int cpu = smp_processor_id();
-       int rc=0;
-
-       /* check for other users first */
-       if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
-                       == NOTIFY_STOP) {
-               rc = 1;
-               touched = 1;
-       }
-
-       if (cpu_isset(cpu, backtrace_mask)) {
-               static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
-
-               spin_lock(&lock);
-               printk("NMI backtrace for cpu %d\n", cpu);
-               dump_stack();
-               spin_unlock(&lock);
-               cpu_clear(cpu, backtrace_mask);
-       }
-
-       /*
-        * Take the local apic timer and PIT/HPET into account. We don't
-        * know which one is active, when we have highres/dyntick on
-        */
-       sum = per_cpu(irq_stat, cpu).apic_timer_irqs + kstat_cpu(cpu).irqs[0];
-
-       /* if the none of the timers isn't firing, this cpu isn't doing much */
-       if (!touched && last_irq_sums[cpu] == sum) {
-               /*
-                * Ayiee, looks like this CPU is stuck ...
-                * wait a few IRQs (5 seconds) before doing the oops ...
-                */
-               alert_counter[cpu]++;
-               if (alert_counter[cpu] == 5*nmi_hz)
-                       /*
-                        * die_nmi will return ONLY if NOTIFY_STOP happens..
-                        */
-                       die_nmi(regs, "BUG: NMI Watchdog detected LOCKUP");
-       } else {
-               last_irq_sums[cpu] = sum;
-               alert_counter[cpu] = 0;
-       }
-       /* see if the nmi watchdog went off */
-       if (!__get_cpu_var(wd_enabled))
-               return rc;
-       switch (nmi_watchdog) {
-       case NMI_LOCAL_APIC:
-               rc |= lapic_wd_event(nmi_hz);
-               break;
-       case NMI_IO_APIC:
-               /* don't know how to accurately check for this.
-                * just assume it was a watchdog timer interrupt
-                * This matches the old behaviour.
-                */
-               rc = 1;
-               break;
-       }
-       return rc;
-}
-
-int do_nmi_callback(struct pt_regs * regs, int cpu)
-{
-#ifdef CONFIG_SYSCTL
-       if (unknown_nmi_panic)
-               return unknown_nmi_panic_callback(regs, cpu);
-#endif
-       return 0;
-}
-
-#ifdef CONFIG_SYSCTL
-
-static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
-{
-       unsigned char reason = get_nmi_reason();
-       char buf[64];
-
-       sprintf(buf, "NMI received for unknown reason %02x\n", reason);
-       die_nmi(regs, buf);
-       return 0;
-}
-
-/*
- * proc handler for /proc/sys/kernel/nmi
- */
-int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
-                       void __user *buffer, size_t *length, loff_t *ppos)
-{
-       int old_state;
-
-       nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;
-       old_state = nmi_watchdog_enabled;
-       proc_dointvec(table, write, file, buffer, length, ppos);
-       if (!!old_state == !!nmi_watchdog_enabled)
-               return 0;
-
-       if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) {
-               printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
-               return -EIO;
-       }
-
-       if (nmi_watchdog == NMI_DEFAULT) {
-               if (lapic_watchdog_ok())
-                       nmi_watchdog = NMI_LOCAL_APIC;
-               else
-                       nmi_watchdog = NMI_IO_APIC;
-       }
-
-       if (nmi_watchdog == NMI_LOCAL_APIC) {
-               if (nmi_watchdog_enabled)
-                       enable_lapic_nmi_watchdog();
-               else
-                       disable_lapic_nmi_watchdog();
-       } else {
-               printk( KERN_WARNING
-                       "NMI watchdog doesn't know what hardware to touch\n");
-               return -EIO;
-       }
-       return 0;
-}
-
-#endif
-
-void __trigger_all_cpu_backtrace(void)
-{
-       int i;
-
-       backtrace_mask = cpu_online_map;
-       /* Wait for up to 10 seconds for all CPUs to do the backtrace */
-       for (i = 0; i < 10 * 1000; i++) {
-               if (cpus_empty(backtrace_mask))
-                       break;
-               mdelay(1);
-       }
-}
-
-EXPORT_SYMBOL(nmi_active);
-EXPORT_SYMBOL(nmi_watchdog);
diff --git a/arch/i386/kernel/nmi_32.c b/arch/i386/kernel/nmi_32.c
new file mode 100644 (file)
index 0000000..c7227e2
--- /dev/null
@@ -0,0 +1,468 @@
+/*
+ *  linux/arch/i386/nmi.c
+ *
+ *  NMI watchdog support on APIC systems
+ *
+ *  Started by Ingo Molnar <mingo@redhat.com>
+ *
+ *  Fixes:
+ *  Mikael Pettersson  : AMD K7 support for local APIC NMI watchdog.
+ *  Mikael Pettersson  : Power Management for local APIC NMI watchdog.
+ *  Mikael Pettersson  : Pentium 4 support for local APIC NMI watchdog.
+ *  Pavel Machek and
+ *  Mikael Pettersson  : PM converted to driver model. Disable/enable API.
+ */
+
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/nmi.h>
+#include <linux/sysdev.h>
+#include <linux/sysctl.h>
+#include <linux/percpu.h>
+#include <linux/kprobes.h>
+#include <linux/cpumask.h>
+#include <linux/kernel_stat.h>
+#include <linux/kdebug.h>
+
+#include <asm/smp.h>
+#include <asm/nmi.h>
+
+#include "mach_traps.h"
+
+int unknown_nmi_panic;
+int nmi_watchdog_enabled;
+
+static cpumask_t backtrace_mask = CPU_MASK_NONE;
+
+/* nmi_active:
+ * >0: the lapic NMI watchdog is active, but can be disabled
+ * <0: the lapic NMI watchdog has not been set up, and cannot
+ *     be enabled
+ *  0: the lapic NMI watchdog is disabled, but can be enabled
+ */
+atomic_t nmi_active = ATOMIC_INIT(0);          /* oprofile uses this */
+
+unsigned int nmi_watchdog = NMI_DEFAULT;
+static unsigned int nmi_hz = HZ;
+
+static DEFINE_PER_CPU(short, wd_enabled);
+
+/* local prototypes */
+static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu);
+
+static int endflag __initdata = 0;
+
+#ifdef CONFIG_SMP
+/* The performance counters used by NMI_LOCAL_APIC don't trigger when
+ * the CPU is idle. To make sure the NMI watchdog really ticks on all
+ * CPUs during the test make them busy.
+ */
+static __init void nmi_cpu_busy(void *data)
+{
+       local_irq_enable_in_hardirq();
+       /* Intentionally don't use cpu_relax here. This is
+          to make sure that the performance counter really ticks,
+          even if there is a simulator or similar that catches the
+          pause instruction. On a real HT machine this is fine because
+          all other CPUs are busy with "useless" delay loops and don't
+          care if they get somewhat less cycles. */
+       while (endflag == 0)
+               mb();
+}
+#endif
+
+static int __init check_nmi_watchdog(void)
+{
+       unsigned int *prev_nmi_count;
+       int cpu;
+
+       if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DISABLED))
+               return 0;
+
+       if (!atomic_read(&nmi_active))
+               return 0;
+
+       prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
+       if (!prev_nmi_count)
+               return -1;
+
+       printk(KERN_INFO "Testing NMI watchdog ... ");
+
+       if (nmi_watchdog == NMI_LOCAL_APIC)
+               smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
+
+       for_each_possible_cpu(cpu)
+               prev_nmi_count[cpu] = per_cpu(irq_stat, cpu).__nmi_count;
+       local_irq_enable();
+       mdelay((20*1000)/nmi_hz); // wait 20 ticks
+
+       for_each_possible_cpu(cpu) {
+#ifdef CONFIG_SMP
+               /* Check cpu_callin_map here because that is set
+                  after the timer is started. */
+               if (!cpu_isset(cpu, cpu_callin_map))
+                       continue;
+#endif
+               if (!per_cpu(wd_enabled, cpu))
+                       continue;
+               if (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {
+                       printk("CPU#%d: NMI appears to be stuck (%d->%d)!\n",
+                               cpu,
+                               prev_nmi_count[cpu],
+                               nmi_count(cpu));
+                       per_cpu(wd_enabled, cpu) = 0;
+                       atomic_dec(&nmi_active);
+               }
+       }
+       endflag = 1;
+       if (!atomic_read(&nmi_active)) {
+               kfree(prev_nmi_count);
+               atomic_set(&nmi_active, -1);
+               return -1;
+       }
+       printk("OK.\n");
+
+       /* now that we know it works we can reduce NMI frequency to
+          something more reasonable; makes a difference in some configs */
+       if (nmi_watchdog == NMI_LOCAL_APIC)
+               nmi_hz = lapic_adjust_nmi_hz(1);
+
+       kfree(prev_nmi_count);
+       return 0;
+}
+/* This needs to happen later in boot so counters are working */
+late_initcall(check_nmi_watchdog);
+
+static int __init setup_nmi_watchdog(char *str)
+{
+       int nmi;
+
+       get_option(&str, &nmi);
+
+       if ((nmi >= NMI_INVALID) || (nmi < NMI_NONE))
+               return 0;
+
+       nmi_watchdog = nmi;
+       return 1;
+}
+
+__setup("nmi_watchdog=", setup_nmi_watchdog);
+
+
+/* Suspend/resume support */
+
+#ifdef CONFIG_PM
+
+static int nmi_pm_active; /* nmi_active before suspend */
+
+static int lapic_nmi_suspend(struct sys_device *dev, pm_message_t state)
+{
+       /* only CPU0 goes here, other CPUs should be offline */
+       nmi_pm_active = atomic_read(&nmi_active);
+       stop_apic_nmi_watchdog(NULL);
+       BUG_ON(atomic_read(&nmi_active) != 0);
+       return 0;
+}
+
+static int lapic_nmi_resume(struct sys_device *dev)
+{
+       /* only CPU0 goes here, other CPUs should be offline */
+       if (nmi_pm_active > 0) {
+               setup_apic_nmi_watchdog(NULL);
+               touch_nmi_watchdog();
+       }
+       return 0;
+}
+
+
+static struct sysdev_class nmi_sysclass = {
+       set_kset_name("lapic_nmi"),
+       .resume         = lapic_nmi_resume,
+       .suspend        = lapic_nmi_suspend,
+};
+
+static struct sys_device device_lapic_nmi = {
+       .id     = 0,
+       .cls    = &nmi_sysclass,
+};
+
+static int __init init_lapic_nmi_sysfs(void)
+{
+       int error;
+
+       /* should really be a BUG_ON but b/c this is an
+        * init call, it just doesn't work.  -dcz
+        */
+       if (nmi_watchdog != NMI_LOCAL_APIC)
+               return 0;
+
+       if (atomic_read(&nmi_active) < 0)
+               return 0;
+
+       error = sysdev_class_register(&nmi_sysclass);
+       if (!error)
+               error = sysdev_register(&device_lapic_nmi);
+       return error;
+}
+/* must come after the local APIC's device_initcall() */
+late_initcall(init_lapic_nmi_sysfs);
+
+#endif /* CONFIG_PM */
+
+static void __acpi_nmi_enable(void *__unused)
+{
+       apic_write_around(APIC_LVT0, APIC_DM_NMI);
+}
+
+/*
+ * Enable timer based NMIs on all CPUs:
+ */
+void acpi_nmi_enable(void)
+{
+       if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
+               on_each_cpu(__acpi_nmi_enable, NULL, 0, 1);
+}
+
+static void __acpi_nmi_disable(void *__unused)
+{
+       apic_write(APIC_LVT0, APIC_DM_NMI | APIC_LVT_MASKED);
+}
+
+/*
+ * Disable timer based NMIs on all CPUs:
+ */
+void acpi_nmi_disable(void)
+{
+       if (atomic_read(&nmi_active) && nmi_watchdog == NMI_IO_APIC)
+               on_each_cpu(__acpi_nmi_disable, NULL, 0, 1);
+}
+
+void setup_apic_nmi_watchdog (void *unused)
+{
+       if (__get_cpu_var(wd_enabled))
+               return;
+
+       /* cheap hack to support suspend/resume */
+       /* if cpu0 is not active neither should the other cpus */
+       if ((smp_processor_id() != 0) && (atomic_read(&nmi_active) <= 0))
+               return;
+
+       switch (nmi_watchdog) {
+       case NMI_LOCAL_APIC:
+               __get_cpu_var(wd_enabled) = 1; /* enable it before to avoid race with handler */
+               if (lapic_watchdog_init(nmi_hz) < 0) {
+                       __get_cpu_var(wd_enabled) = 0;
+                       return;
+               }
+               /* FALL THROUGH */
+       case NMI_IO_APIC:
+               __get_cpu_var(wd_enabled) = 1;
+               atomic_inc(&nmi_active);
+       }
+}
+
+void stop_apic_nmi_watchdog(void *unused)
+{
+       /* only support LOCAL and IO APICs for now */
+       if ((nmi_watchdog != NMI_LOCAL_APIC) &&
+           (nmi_watchdog != NMI_IO_APIC))
+               return;
+       if (__get_cpu_var(wd_enabled) == 0)
+               return;
+       if (nmi_watchdog == NMI_LOCAL_APIC)
+               lapic_watchdog_stop();
+       __get_cpu_var(wd_enabled) = 0;
+       atomic_dec(&nmi_active);
+}
+
+/*
+ * the best way to detect whether a CPU has a 'hard lockup' problem
+ * is to check it's local APIC timer IRQ counts. If they are not
+ * changing then that CPU has some problem.
+ *
+ * as these watchdog NMI IRQs are generated on every CPU, we only
+ * have to check the current processor.
+ *
+ * since NMIs don't listen to _any_ locks, we have to be extremely
+ * careful not to rely on unsafe variables. The printk might lock
+ * up though, so we have to break up any console locks first ...
+ * [when there will be more tty-related locks, break them up
+ *  here too!]
+ */
+
+static unsigned int
+       last_irq_sums [NR_CPUS],
+       alert_counter [NR_CPUS];
+
+void touch_nmi_watchdog(void)
+{
+       if (nmi_watchdog > 0) {
+               unsigned cpu;
+
+               /*
+                * Just reset the alert counters, (other CPUs might be
+                * spinning on locks we hold):
+                */
+               for_each_present_cpu(cpu) {
+                       if (alert_counter[cpu])
+                               alert_counter[cpu] = 0;
+               }
+       }
+
+       /*
+        * Tickle the softlockup detector too:
+        */
+       touch_softlockup_watchdog();
+}
+EXPORT_SYMBOL(touch_nmi_watchdog);
+
+extern void die_nmi(struct pt_regs *, const char *msg);
+
+__kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
+{
+
+       /*
+        * Since current_thread_info()-> is always on the stack, and we
+        * always switch the stack NMI-atomically, it's safe to use
+        * smp_processor_id().
+        */
+       unsigned int sum;
+       int touched = 0;
+       int cpu = smp_processor_id();
+       int rc=0;
+
+       /* check for other users first */
+       if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
+                       == NOTIFY_STOP) {
+               rc = 1;
+               touched = 1;
+       }
+
+       if (cpu_isset(cpu, backtrace_mask)) {
+               static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
+
+               spin_lock(&lock);
+               printk("NMI backtrace for cpu %d\n", cpu);
+               dump_stack();
+               spin_unlock(&lock);
+               cpu_clear(cpu, backtrace_mask);
+       }
+
+       /*
+        * Take the local apic timer and PIT/HPET into account. We don't
+        * know which one is active, when we have highres/dyntick on
+        */
+       sum = per_cpu(irq_stat, cpu).apic_timer_irqs + kstat_cpu(cpu).irqs[0];
+
+       /* if the none of the timers isn't firing, this cpu isn't doing much */
+       if (!touched && last_irq_sums[cpu] == sum) {
+               /*
+                * Ayiee, looks like this CPU is stuck ...
+                * wait a few IRQs (5 seconds) before doing the oops ...
+                */
+               alert_counter[cpu]++;
+               if (alert_counter[cpu] == 5*nmi_hz)
+                       /*
+                        * die_nmi will return ONLY if NOTIFY_STOP happens..
+                        */
+                       die_nmi(regs, "BUG: NMI Watchdog detected LOCKUP");
+       } else {
+               last_irq_sums[cpu] = sum;
+               alert_counter[cpu] = 0;
+       }
+       /* see if the nmi watchdog went off */
+       if (!__get_cpu_var(wd_enabled))
+               return rc;
+       switch (nmi_watchdog) {
+       case NMI_LOCAL_APIC:
+               rc |= lapic_wd_event(nmi_hz);
+               break;
+       case NMI_IO_APIC:
+               /* don't know how to accurately check for this.
+                * just assume it was a watchdog timer interrupt
+                * This matches the old behaviour.
+                */
+               rc = 1;
+               break;
+       }
+       return rc;
+}
+
+int do_nmi_callback(struct pt_regs * regs, int cpu)
+{
+#ifdef CONFIG_SYSCTL
+       if (unknown_nmi_panic)
+               return unknown_nmi_panic_callback(regs, cpu);
+#endif
+       return 0;
+}
+
+#ifdef CONFIG_SYSCTL
+
+static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
+{
+       unsigned char reason = get_nmi_reason();
+       char buf[64];
+
+       sprintf(buf, "NMI received for unknown reason %02x\n", reason);
+       die_nmi(regs, buf);
+       return 0;
+}
+
+/*
+ * proc handler for /proc/sys/kernel/nmi
+ */
+int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
+                       void __user *buffer, size_t *length, loff_t *ppos)
+{
+       int old_state;
+
+       nmi_watchdog_enabled = (atomic_read(&nmi_active) > 0) ? 1 : 0;
+       old_state = nmi_watchdog_enabled;
+       proc_dointvec(table, write, file, buffer, length, ppos);
+       if (!!old_state == !!nmi_watchdog_enabled)
+               return 0;
+
+       if (atomic_read(&nmi_active) < 0 || nmi_watchdog == NMI_DISABLED) {
+               printk( KERN_WARNING "NMI watchdog is permanently disabled\n");
+               return -EIO;
+       }
+
+       if (nmi_watchdog == NMI_DEFAULT) {
+               if (lapic_watchdog_ok())
+                       nmi_watchdog = NMI_LOCAL_APIC;
+               else
+                       nmi_watchdog = NMI_IO_APIC;
+       }
+
+       if (nmi_watchdog == NMI_LOCAL_APIC) {
+               if (nmi_watchdog_enabled)
+                       enable_lapic_nmi_watchdog();
+               else
+                       disable_lapic_nmi_watchdog();
+       } else {
+               printk( KERN_WARNING
+                       "NMI watchdog doesn't know what hardware to touch\n");
+               return -EIO;
+       }
+       return 0;
+}
+
+#endif
+
+void __trigger_all_cpu_backtrace(void)
+{
+       int i;
+
+       backtrace_mask = cpu_online_map;
+       /* Wait for up to 10 seconds for all CPUs to do the backtrace */
+       for (i = 0; i < 10 * 1000; i++) {
+               if (cpus_empty(backtrace_mask))
+                       break;
+               mdelay(1);
+       }
+}
+
+EXPORT_SYMBOL(nmi_active);
+EXPORT_SYMBOL(nmi_watchdog);