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