diff options
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/nmi_watchdog.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/kernel/nmi_watchdog.c b/kernel/nmi_watchdog.c new file mode 100644 index 0000000..36817b2 --- /dev/null +++ b/kernel/nmi_watchdog.c @@ -0,0 +1,191 @@ +/* + * Detect Hard Lockups using the NMI + * + * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. + * + * this code detects hard lockups: incidents in where on a CPU + * the kernel does not respond to anything except NMI. + * + * Note: Most of this code is borrowed heavily from softlockup.c, + * so thanks to Ingo for the initial implementation. + * Some chunks also taken from arch/x86/kernel/apic/nmi.c, thanks + * to those contributors as well. + */ + +#include <linux/mm.h> +#include <linux/cpu.h> +#include <linux/nmi.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/freezer.h> +#include <linux/lockdep.h> +#include <linux/notifier.h> +#include <linux/module.h> +#include <linux/sysctl.h> + +#include <asm/irq_regs.h> +#include <linux/perf_event.h> + +static DEFINE_PER_CPU(struct perf_event *, nmi_watchdog_ev); +static DEFINE_PER_CPU(int, nmi_watchdog_touch); +static DEFINE_PER_CPU(long, alert_counter); + +void touch_nmi_watchdog(void) +{ + __raw_get_cpu_var(nmi_watchdog_touch) = 1; + touch_softlockup_watchdog(); +} +EXPORT_SYMBOL(touch_nmi_watchdog); + +void touch_all_nmi_watchdog(void) +{ + int cpu; + + for_each_online_cpu(cpu) + per_cpu(nmi_watchdog_touch, cpu) = 1; + touch_softlockup_watchdog(); +} + +#ifdef CONFIG_SYSCTL +/* + * proc handler for /proc/sys/kernel/nmi_watchdog + */ +int proc_nmi_enabled(struct ctl_table *table, int write, + void __user *buffer, size_t *length, loff_t *ppos) +{ + int cpu; + + if (per_cpu(nmi_watchdog_ev, smp_processor_id()) == NULL) + nmi_watchdog_enabled = 0; + else + nmi_watchdog_enabled = 1; + + touch_all_nmi_watchdog(); + proc_dointvec(table, write, buffer, length, ppos); + if (nmi_watchdog_enabled) + for_each_online_cpu(cpu) + perf_event_enable(per_cpu(nmi_watchdog_ev, cpu)); + else + for_each_online_cpu(cpu) + perf_event_disable(per_cpu(nmi_watchdog_ev, cpu)); + return 0; +} + +#endif /* CONFIG_SYSCTL */ + +struct perf_event_attr wd_attr = { + .type = PERF_TYPE_HARDWARE, + .config = PERF_COUNT_HW_CPU_CYCLES, + .size = sizeof(struct perf_event_attr), + .pinned = 1, + .disabled = 1, +}; + +static int panic_on_timeout; + +void wd_overflow(struct perf_event *event, int nmi, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + int cpu = smp_processor_id(); + int touched = 0; + + if (__get_cpu_var(nmi_watchdog_touch)) { + per_cpu(nmi_watchdog_touch, cpu) = 0; + touched = 1; + } + + /* check to see if the cpu is doing anything */ + if (!touched && hw_nmi_is_cpu_stuck(regs)) { + /* + * Ayiee, looks like this CPU is stuck ... + * wait a few IRQs (5 seconds) before doing the oops ... + */ + per_cpu(alert_counter,cpu) += 1; + if (per_cpu(alert_counter,cpu) == 5) { + /* + * die_nmi will return ONLY if NOTIFY_STOP happens.. + */ + die_nmi("BUG: NMI Watchdog detected LOCKUP", + regs, panic_on_timeout); + } + } else { + per_cpu(alert_counter,cpu) = 0; + } + + return; +} + +/* + * Create/destroy watchdog threads as CPUs come and go: + */ +static int __cpuinit +cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) +{ + int hotcpu = (unsigned long)hcpu; + struct perf_event *event; + + switch (action) { + case CPU_UP_PREPARE: + case CPU_UP_PREPARE_FROZEN: + per_cpu(nmi_watchdog_touch, hotcpu) = 0; + break; + case CPU_ONLINE: + case CPU_ONLINE_FROZEN: + /* originally wanted the below chunk to be in CPU_UP_PREPARE, but caps is unpriv for non-CPU0 */ + wd_attr.sample_period = cpu_khz * 1000; + event = perf_event_create_kernel_counter(&wd_attr, hotcpu, -1, wd_overflow); + if (IS_ERR(event)) { + printk(KERN_ERR "nmi watchdog failed to create perf event on %i: %p\n", hotcpu, event); + return NOTIFY_BAD; + } + per_cpu(nmi_watchdog_ev, hotcpu) = event; + perf_event_enable(per_cpu(nmi_watchdog_ev, hotcpu)); + break; +#ifdef CONFIG_HOTPLUG_CPU + case CPU_UP_CANCELED: + case CPU_UP_CANCELED_FROZEN: + perf_event_disable(per_cpu(nmi_watchdog_ev, hotcpu)); + case CPU_DEAD: + case CPU_DEAD_FROZEN: + event = per_cpu(nmi_watchdog_ev, hotcpu); + per_cpu(nmi_watchdog_ev, hotcpu) = NULL; + perf_event_release_kernel(event); + break; +#endif /* CONFIG_HOTPLUG_CPU */ + } + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata cpu_nfb = { + .notifier_call = cpu_callback +}; + +static int __initdata nonmi_watchdog; + +static int __init nonmi_watchdog_setup(char *str) +{ + nonmi_watchdog = 1; + return 1; +} +__setup("nonmi_watchdog", nonmi_watchdog_setup); + +static int __init spawn_nmi_watchdog_task(void) +{ + void *cpu = (void *)(long)smp_processor_id(); + int err; + + if (nonmi_watchdog) + return 0; + + err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu); + if (err == NOTIFY_BAD) { + BUG(); + return 1; + } + cpu_callback(&cpu_nfb, CPU_ONLINE, cpu); + register_cpu_notifier(&cpu_nfb); + + return 0; +} +early_initcall(spawn_nmi_watchdog_task); |