1 files changed, 516 insertions, 0 deletions

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
new file mode 100644
index 000000000000..ec024b3baad0
--- /dev/null
+++ b/arch/x86/kernel/nmi.c
@@ -0,0 +1,516 @@
+/*
+ *  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 <asm/apic.h>
+
+#include <linux/nmi.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/module.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 <linux/smp.h>
+
+#include <asm/i8259.h>
+#include <asm/io_apic.h>
+#include <asm/smp.h>
+#include <asm/nmi.h>
+#include <asm/proto.h>
+#include <asm/timer.h>
+
+#include <asm/mce.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 */
+EXPORT_SYMBOL(nmi_active);
+
+unsigned int nmi_watchdog = NMI_NONE;
+EXPORT_SYMBOL(nmi_watchdog);
+
+static int panic_on_timeout;
+
+static unsigned int nmi_hz = HZ;
+static DEFINE_PER_CPU(short, wd_enabled);
+static int endflag __initdata;
+
+static inline unsigned int get_nmi_count(int cpu)
+{
+#ifdef CONFIG_X86_64
+        return cpu_pda(cpu)->__nmi_count;
+#else
+        return nmi_count(cpu);
+#endif
+}
+
+static inline int mce_in_progress(void)
+{
+#if defined(CONFIG_X86_64) && defined(CONFIG_X86_MCE)
+        return atomic_read(&mce_entry) > 0;
+#endif
+        return 0;
+}
+
+/*
+ * Take the local apic timer and PIT/HPET into account. We don't
+ * know which one is active, when we have highres/dyntick on
+ */
+static inline unsigned int get_timer_irqs(int cpu)
+{
+#ifdef CONFIG_X86_64
+        return read_pda(apic_timer_irqs) + read_pda(irq0_irqs);
+#else
+        return per_cpu(irq_stat, cpu).apic_timer_irqs +
+                per_cpu(irq_stat, cpu).irq0_irqs;
+#endif
+}
+
+#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
+
+int __init check_nmi_watchdog(void)
+{
+        unsigned int *prev_nmi_count;
+        int cpu;
+
+        if (!nmi_watchdog_active() || !atomic_read(&nmi_active))
+                return 0;
+
+        prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
+        if (!prev_nmi_count)
+                goto error;
+
+        printk(KERN_INFO "Testing NMI watchdog ... ");
+
+#ifdef CONFIG_SMP
+        if (nmi_watchdog == NMI_LOCAL_APIC)
+                smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
+#endif
+
+        for_each_possible_cpu(cpu)
+                prev_nmi_count[cpu] = get_nmi_count(cpu);
+        local_irq_enable();
+        mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
+
+        for_each_online_cpu(cpu) {
+                if (!per_cpu(wd_enabled, cpu))
+                        continue;
+                if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {
+                        printk(KERN_WARNING "WARNING: CPU#%d: NMI "
+                                "appears to be stuck (%d->%d)!\n",
+                                cpu,
+                                prev_nmi_count[cpu],
+                                get_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);
+                goto error;
+        }
+        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;
+error:
+        if (nmi_watchdog == NMI_IO_APIC && !timer_through_8259)
+                disable_8259A_irq(0);
+#ifdef CONFIG_X86_32
+        timer_ack = 0;
+#endif
+        return -1;
+}
+
+static int __init setup_nmi_watchdog(char *str)
+{
+        unsigned int nmi;
+
+        if (!strncmp(str, "panic", 5)) {
+                panic_on_timeout = 1;
+                str = strchr(str, ',');
+                if (!str)
+                        return 1;
+                ++str;
+        }
+
+        get_option(&str, &nmi);
+
+        if (nmi >= NMI_INVALID)
+                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 = {
+        .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, 1);
+}
+
+static void __acpi_nmi_disable(void *__unused)
+{
+        apic_write_around(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, 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:
+                 /* enable it before to avoid race with handler */
+                __get_cpu_var(wd_enabled) = 1;
+                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_active())
+                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 DEFINE_PER_CPU(unsigned, last_irq_sum);
+static DEFINE_PER_CPU(local_t, alert_counter);
+static DEFINE_PER_CPU(int, nmi_touch);
+
+void touch_nmi_watchdog(void)
+{
+        if (nmi_watchdog_active()) {
+                unsigned cpu;
+
+                /*
+                 * Tell other CPUs to reset their alert counters. We cannot
+                 * do it ourselves because the alert count increase is not
+                 * atomic.
+                 */
+                for_each_present_cpu(cpu) {
+                        if (per_cpu(nmi_touch, cpu) != 1)
+                                per_cpu(nmi_touch, cpu) = 1;
+                }
+        }
+
+        /*
+         * Tickle the softlockup detector too:
+         */
+        touch_softlockup_watchdog();
+}
+EXPORT_SYMBOL(touch_nmi_watchdog);
+
+notrace __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;
+        }
+
+        sum = get_timer_irqs(cpu);
+
+        if (__get_cpu_var(nmi_touch)) {
+                __get_cpu_var(nmi_touch) = 0;
+                touched = 1;
+        }
+
+        if (cpu_isset(cpu, backtrace_mask)) {
+                static DEFINE_SPINLOCK(lock);   /* Serialise the printks */
+
+                spin_lock(&lock);
+                printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
+                dump_stack();
+                spin_unlock(&lock);
+                cpu_clear(cpu, backtrace_mask);
+        }
+
+        /* Could check oops_in_progress here too, but it's safer not to */
+        if (mce_in_progress())
+                touched = 1;
+
+        /* if the none of the timers isn't firing, this cpu isn't doing much */
+        if (!touched && __get_cpu_var(last_irq_sum) == sum) {
+                /*
+                 * Ayiee, looks like this CPU is stuck ...
+                 * wait a few IRQs (5 seconds) before doing the oops ...
+                 */
+                local_inc(&__get_cpu_var(alert_counter));
+                if (local_read(&__get_cpu_var(alert_counter)) == 5 * nmi_hz)
+                        /*
+                         * die_nmi will return ONLY if NOTIFY_STOP happens..
+                         */
+                        die_nmi("BUG: NMI Watchdog detected LOCKUP",
+                                regs, panic_on_timeout);
+        } else {
+                __get_cpu_var(last_irq_sum) = sum;
+                local_set(&__get_cpu_var(alert_counter), 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;
+}
+
+#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(buf, regs, 1); /* Always panic here */
+        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_active()) {
+                printk(KERN_WARNING
+                        "NMI watchdog is permanently disabled\n");
+                return -EIO;
+        }
+
+        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 /* CONFIG_SYSCTL */
+
+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;
+}
+
+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);
+        }
+}