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 #ifdef CONFIG_HARDLOCKUP_DETECTOR
  21 u64 hw_nmi_get_sample_period(void)
  22 {
  23         return (u64)(cpu_khz) * 1000 * 60;
  24 }
  25 #endif
  26
  27 #ifdef arch_trigger_all_cpu_backtrace
  28 /* For reliability, we're prepared to waste bits here. */
  29 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
  30
  31 /* "in progress" flag of arch_trigger_all_cpu_backtrace */
  32 static unsigned long backtrace_flag;
  33
  34 void arch_trigger_all_cpu_backtrace(void)
  35 {
  36         int i;
  37
  38         if (test_and_set_bit(0, &backtrace_flag))
  39                 /*
  40                  * If there is already a trigger_all_cpu_backtrace() in progress
  41                  * (backtrace_flag == 1), don't output double cpu dump infos.
  42                  */
  43                 return;
  44
  45         cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
  46
  47         printk(KERN_INFO "sending NMI to all CPUs:\n");
  48         apic->send_IPI_all(NMI_VECTOR);
  49
  50         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
  51         for (i = 0; i < 10 * 1000; i++) {
  52                 if (cpumask_empty(to_cpumask(backtrace_mask)))
  53                         break;
  54                 mdelay(1);
  55         }
  56
  57         clear_bit(0, &backtrace_flag);
  58         smp_mb__after_clear_bit();
  59 }
  60
  61 static int __kprobes
  62 arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self,
  63                          unsigned long cmd, void *__args)
  64 {
  65         struct die_args *args = __args;
  66         struct pt_regs *regs;
  67         int cpu;
  68
  69         switch (cmd) {
  70         case DIE_NMI:
  71                 break;
  72
  73         default:
  74                 return NOTIFY_DONE;
  75         }
  76
  77         regs = args->regs;
  78         cpu = smp_processor_id();
  79
  80         if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
  81                 static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
  82
  83                 arch_spin_lock(&lock);
  84                 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
  85                 show_regs(regs);
  86                 dump_stack();
  87                 arch_spin_unlock(&lock);
  88                 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
  89                 return NOTIFY_STOP;
  90         }
  91
  92         return NOTIFY_DONE;
  93 }
  94
  95 static __read_mostly struct notifier_block backtrace_notifier = {
  96         .notifier_call          = arch_trigger_all_cpu_backtrace_handler,
  97         .next                   = NULL,
  98         .priority               = NMI_LOCAL_LOW_PRIOR,
  99 };
 100
 101 static int __init register_trigger_all_cpu_backtrace(void)
 102 {
 103         register_die_notifier(&backtrace_notifier);
 104         return 0;
 105 }
 106 early_initcall(register_trigger_all_cpu_backtrace);
 107 #endif