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