-/*
- * 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);
-
-static int panic_on_timeout;
-
-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();
-}
-
-static int __init setup_nmi_watchdog(char *str)
-{
- if (!strncmp(str, "panic", 5)) {
- panic_on_timeout = 1;
- str = strchr(str, ',');
- if (!str)
- return 1;
- ++str;
- }
- return 1;
-}
-__setup("nmi_watchdog=", setup_nmi_watchdog);
-
-struct perf_event_attr wd_hw_attr = {
- .type = PERF_TYPE_HARDWARE,
- .config = PERF_COUNT_HW_CPU_CYCLES,
- .size = sizeof(struct perf_event_attr),
- .pinned = 1,
- .disabled = 1,
-};
-
-struct perf_event_attr wd_sw_attr = {
- .type = PERF_TYPE_SOFTWARE,
- .config = PERF_COUNT_SW_CPU_CLOCK,
- .size = sizeof(struct perf_event_attr),
- .pinned = 1,
- .disabled = 1,
-};
-
-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) {
- if (panic_on_timeout)
- panic("NMI Watchdog detected LOCKUP on cpu %d", cpu);
- else
- WARN(1, "NMI Watchdog detected LOCKUP on cpu %d", cpu);
- }
- } else {
- per_cpu(alert_counter, cpu) = 0;
- }
-
- return;
-}
-
-static int enable_nmi_watchdog(int cpu)
-{
- struct perf_event *event;
- struct perf_event_attr *wd_attr;
-
- event = per_cpu(nmi_watchdog_ev, cpu);
- if (event && event->state > PERF_EVENT_STATE_OFF)
- return 0;
-
- if (event == NULL) {
- /* Try to register using hardware perf events first */
- wd_attr = &wd_hw_attr;
- wd_attr->sample_period = hw_nmi_get_sample_period();
- event = perf_event_create_kernel_counter(wd_attr, cpu, -1, wd_overflow);
- if (IS_ERR(event)) {
- /* hardware doesn't exist or not supported, fallback to software events */
- printk(KERN_INFO "nmi_watchdog: hardware not available, trying software events\n");
- wd_attr = &wd_sw_attr;
- wd_attr->sample_period = NSEC_PER_SEC;
- event = perf_event_create_kernel_counter(wd_attr, cpu, -1, wd_overflow);
- if (IS_ERR(event)) {
- printk(KERN_ERR "nmi watchdog failed to create perf event on %i: %p\n", cpu, event);
- return -1;
- }
- }
- per_cpu(nmi_watchdog_ev, cpu) = event;
- }
- perf_event_enable(per_cpu(nmi_watchdog_ev, cpu));
- return 0;
-}
-
-static void disable_nmi_watchdog(int cpu)
-{
- struct perf_event *event;
-
- event = per_cpu(nmi_watchdog_ev, cpu);
- if (event) {
- perf_event_disable(per_cpu(nmi_watchdog_ev, cpu));
- per_cpu(nmi_watchdog_ev, cpu) = NULL;
- perf_event_release_kernel(event);
- }
-}
-
-#ifdef CONFIG_SYSCTL
-/*
- * proc handler for /proc/sys/kernel/nmi_watchdog
- */
-int nmi_watchdog_enabled;
-
-int proc_nmi_enabled(struct ctl_table *table, int write,
- void __user *buffer, size_t *length, loff_t *ppos)
-{
- int cpu;
-
- if (!write) {
- struct perf_event *event;
- for_each_online_cpu(cpu) {
- event = per_cpu(nmi_watchdog_ev, cpu);
- if (event && event->state > PERF_EVENT_STATE_OFF) {
- nmi_watchdog_enabled = 1;
- break;
- }
- }
- proc_dointvec(table, write, buffer, length, ppos);
- return 0;
- }
-
- touch_all_nmi_watchdog();
- proc_dointvec(table, write, buffer, length, ppos);
- if (nmi_watchdog_enabled) {
- for_each_online_cpu(cpu)
- if (enable_nmi_watchdog(cpu)) {
- printk(KERN_ERR "NMI watchdog failed configuration, "
- " can not be enabled\n");
- }
- } else {
- for_each_online_cpu(cpu)
- disable_nmi_watchdog(cpu);
- }
- return 0;
-}
-
-#endif /* CONFIG_SYSCTL */
-
-/*
- * 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;
-
- 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:
- if (enable_nmi_watchdog(hotcpu))
- return NOTIFY_BAD;
- break;
-#ifdef CONFIG_HOTPLUG_CPU
- case CPU_UP_CANCELED:
- case CPU_UP_CANCELED_FROZEN:
- disable_nmi_watchdog(hotcpu);
- case CPU_DEAD:
- case CPU_DEAD_FROZEN:
- 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;
-
- printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
-
- 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);
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