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