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 #include <linux/delay.h>
  20
  21 #ifdef CONFIG_HARDLOCKUP_DETECTOR
  22 u64 hw_nmi_get_sample_period(int watchdog_thresh)
  23 {
  24         return (u64)(cpu_khz) * 1000 * watchdog_thresh;
  25 }
  26 #endif
  27
  28 #ifdef arch_trigger_all_cpu_backtrace
  29 #ifdef CONFIG_XEN
  30 #include <asm/ipi.h>
  31 #endif
  32
  33 /* For reliability, we're prepared to waste bits here. */
  34 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
  35
  36 /* "in progress" flag of arch_trigger_all_cpu_backtrace */
  37 static unsigned long backtrace_flag;
  38
  39 void arch_trigger_all_cpu_backtrace(void)
  40 {
  41         int i;
  42
  43         if (test_and_set_bit(0, &backtrace_flag))
  44                 /*
  45                  * If there is already a trigger_all_cpu_backtrace() in progress
  46                  * (backtrace_flag == 1), don't output double cpu dump infos.
  47                  */
  48                 return;
  49
  50         cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
  51
  52         printk(KERN_INFO "sending NMI to all CPUs:\n");
  53 #ifndef CONFIG_XEN
  54         apic->send_IPI_all(NMI_VECTOR);
  55 #else /* this works even without CONFIG_X86_LOCAL_APIC */
  56         xen_send_IPI_all(NMI_VECTOR);
  57 #endif
  58
  59         /* Wait for up to 10 seconds for all CPUs to do the backtrace */
  60         for (i = 0; i < 10 * 1000; i++) {
  61                 if (cpumask_empty(to_cpumask(backtrace_mask)))
  62                         break;
  63                 mdelay(1);
  64         }
  65
  66         clear_bit(0, &backtrace_flag);
  67         smp_mb__after_clear_bit();
  68 }
  69
  70 static int __kprobes
  71 arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
  72 {
  73         int cpu;
  74
  75         cpu = smp_processor_id();
  76
  77         if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
  78                 static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
  79
  80                 arch_spin_lock(&lock);
  81                 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
  82                 show_regs(regs);
  83                 arch_spin_unlock(&lock);
  84                 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
  85                 return NMI_HANDLED;
  86         }
  87
  88         return NMI_DONE;
  89 }
  90
  91 static int __init register_trigger_all_cpu_backtrace(void)
  92 {
  93         register_nmi_handler(NMI_LOCAL, arch_trigger_all_cpu_backtrace_handler,
  94                                 0, "arch_bt");
  95         return 0;
  96 }
  97 early_initcall(register_trigger_all_cpu_backtrace);
  98 #endif