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-rw-r--r--kernel/nmi_watchdog.c191
1 files changed, 191 insertions, 0 deletions
diff --git a/kernel/nmi_watchdog.c b/kernel/nmi_watchdog.c
new file mode 100644
index 00000000000..36817b214d6
--- /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);