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 #include <asm/nmi.h>
  13
  14 #include <linux/cpumask.h>
  15 #include <linux/kdebug.h>
  16 #include <linux/notifier.h>
  17 #include <linux/kprobes.h>
  18 #include <linux/nmi.h>
  19 #include <linux/module.h>
  20 #include <linux/delay.h>
  21
  22 #ifdef CONFIG_HARDLOCKUP_DETECTOR
  23 u64 hw_nmi_get_sample_period(int watchdog_thresh)
  24 {
  25         return (u64)(cpu_khz) * 1000 * watchdog_thresh;
  26 }
  27 #endif
  28
  29 #ifdef arch_trigger_all_cpu_backtrace
  30 /* For reliability, we're prepared to waste bits here. */
  31 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
  32
  33 /* "in progress" flag of arch_trigger_all_cpu_backtrace */
  34 static unsigned long backtrace_flag;
  35
  36 void arch_trigger_all_cpu_backtrace(void)
  37 {
  38         int i;
  39
  40         if (test_and_set_bit(0, &backtrace_flag))
  41                 /*
  42                  * If there is already a trigger_all_cpu_backtrace() in progress
  43                  * (backtrace_flag == 1), don't output double cpu dump infos.
  44                  */
  45                 return;
  46
  47         cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
  48
  49         printk(KERN_INFO "sending NMI to all CPUs:\n");
  50         apic->send_IPI_all(NMI_VECTOR);
  51
  52         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
  53         for (i = 0; i < 10 * 1000; i++) {
  54                 if (cpumask_empty(to_cpumask(backtrace_mask)))
  55                         break;
  56                 mdelay(1);
  57         }
  58
  59         clear_bit(0, &backtrace_flag);
  60         smp_mb__after_clear_bit();
  61 }
  62
  63 static int __kprobes
  64 arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
  65 {
  66         int cpu;
  67
  68         cpu = smp_processor_id();
  69
  70         if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
  71                 static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
  72
  73                 arch_spin_lock(&lock);
  74                 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
  75                 show_regs(regs);
  76                 arch_spin_unlock(&lock);
  77                 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
  78                 return NMI_HANDLED;
  79         }
  80
  81         return NMI_DONE;
  82 }
  83
  84 static int __init register_trigger_all_cpu_backtrace(void)
  85 {
  86         register_nmi_handler(NMI_LOCAL, arch_trigger_all_cpu_backtrace_handler,
  87                                 0, "arch_bt");
  88         return 0;
  89 }
  90 early_initcall(register_trigger_all_cpu_backtrace);
  91 #endif