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(bool include_self)
  37 {
  38         int i;
  39         int cpu = get_cpu();
  40
  41         if (test_and_set_bit(0, &backtrace_flag)) {
  42                 /*
  43                  * If there is already a trigger_all_cpu_backtrace() in progress
  44                  * (backtrace_flag == 1), don't output double cpu dump infos.
  45                  */
  46                 put_cpu();
  47                 return;
  48         }
  49
  50         cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
  51         if (!include_self)
  52                 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
  53
  54         if (!cpumask_empty(to_cpumask(backtrace_mask))) {
  55                 pr_info("sending NMI to %s CPUs:\n",
  56                         (include_self ? "all" : "other"));
  57                 apic->send_IPI_mask(to_cpumask(backtrace_mask), NMI_VECTOR);
  58         }
  59
  60         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
  61         for (i = 0; i < 10 * 1000; i++) {
  62                 if (cpumask_empty(to_cpumask(backtrace_mask)))
  63                         break;
  64                 mdelay(1);
  65                 touch_softlockup_watchdog();
  66         }
  67
  68         clear_bit(0, &backtrace_flag);
  69         smp_mb__after_atomic();
  70         put_cpu();
  71 }
  72
  73 static int
  74 arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
  75 {
  76         int cpu;
  77
  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                 arch_spin_unlock(&lock);
  87                 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
  88                 return NMI_HANDLED;
  89         }
  90
  91         return NMI_DONE;
  92 }
  93 NOKPROBE_SYMBOL(arch_trigger_all_cpu_backtrace_handler);
  94
  95 static int __init register_trigger_all_cpu_backtrace(void)
  96 {
  97         register_nmi_handler(NMI_LOCAL, arch_trigger_all_cpu_backtrace_handler,
  98                                 0, "arch_bt");
  99         return 0;
 100 }
 101 early_initcall(register_trigger_all_cpu_backtrace);
 102 #endif