arch/x86/kernel/apic/hw_nmi.c

   1 /*
   2  *  HW NMI watchdog support
   3  *
   4  *  started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
   5  *
   6  *  Arch specific calls to support NMI watchdog
   7  *
   8  *  Bits copied from original nmi.c file
   9  *
  10  */
  11 #include <asm/apic.h>
  12
  13 #include <linux/cpumask.h>
  14 #include <linux/kdebug.h>
  15 #include <linux/notifier.h>
  16 #include <linux/kprobes.h>
  17 #include <linux/nmi.h>
  18 #include <linux/module.h>
  19
  20 u64 hw_nmi_get_sample_period(void)
  21 {
  22         return (u64)(cpu_khz) * 1000 * 60;
  23 }
  24
  25 #ifdef ARCH_HAS_NMI_WATCHDOG
  26
  27 /* For reliability, we're prepared to waste bits here. */
  28 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
  29
  30 void arch_trigger_all_cpu_backtrace(void)
  31 {
  32         int i;
  33
  34         cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
  35
  36         printk(KERN_INFO "sending NMI to all CPUs:\n");
  37         apic->send_IPI_all(NMI_VECTOR);
  38
  39         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
  40         for (i = 0; i < 10 * 1000; i++) {
  41                 if (cpumask_empty(to_cpumask(backtrace_mask)))
  42                         break;
  43                 mdelay(1);
  44         }
  45 }
  46
  47 static int __kprobes
  48 arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self,
  49                          unsigned long cmd, void *__args)
  50 {
  51         struct die_args *args = __args;
  52         struct pt_regs *regs;
  53         int cpu = smp_processor_id();
  54
  55         switch (cmd) {
  56         case DIE_NMI:
  57         case DIE_NMI_IPI:
  58                 break;
  59
  60         default:
  61                 return NOTIFY_DONE;
  62         }
  63
  64         regs = args->regs;
  65
  66         if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
  67                 static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
  68
  69                 arch_spin_lock(&lock);
  70                 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
  71                 show_regs(regs);
  72                 dump_stack();
  73                 arch_spin_unlock(&lock);
  74                 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
  75                 return NOTIFY_STOP;
  76         }
  77
  78         return NOTIFY_DONE;
  79 }
  80
  81 static __read_mostly struct notifier_block backtrace_notifier = {
  82         .notifier_call          = arch_trigger_all_cpu_backtrace_handler,
  83         .next                   = NULL,
  84         .priority               = 1
  85 };
  86
  87 static int __init register_trigger_all_cpu_backtrace(void)
  88 {
  89         register_die_notifier(&backtrace_notifier);
  90         return 0;
  91 }
  92 early_initcall(register_trigger_all_cpu_backtrace);
  93 #endif
  94
  95 /* STUB calls to mimic old nmi_watchdog behaviour */
  96 #if defined(CONFIG_X86_LOCAL_APIC)
  97 unsigned int nmi_watchdog = NMI_NONE;
  98 EXPORT_SYMBOL(nmi_watchdog);
  99 void acpi_nmi_enable(void) { return; }
 100 void acpi_nmi_disable(void) { return; }
 101 #endif
 102 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
 103 EXPORT_SYMBOL(nmi_active);
 104 int unknown_nmi_panic;
 105 void cpu_nmi_set_wd_enabled(void) { return; }
 106 void stop_apic_nmi_watchdog(void *unused) { return; }
 107 void setup_apic_nmi_watchdog(void *unused) { return; }
 108 int __init check_nmi_watchdog(void) { return 0; }