2 * HW NMI watchdog support
4 * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
6 * Arch specific calls to support NMI watchdog
8 * Bits copied from original nmi.c file
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>
22 #ifdef CONFIG_HARDLOCKUP_DETECTOR
23 u64 hw_nmi_get_sample_period(int watchdog_thresh)
25 return (u64)(cpu_khz) * 1000 * watchdog_thresh;
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;
33 /* "in progress" flag of arch_trigger_all_cpu_backtrace */
34 static unsigned long backtrace_flag;
36 void arch_trigger_all_cpu_backtrace(void)
40 if (test_and_set_bit(0, &backtrace_flag))
42 * If there is already a trigger_all_cpu_backtrace() in progress
43 * (backtrace_flag == 1), don't output double cpu dump infos.
47 cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
49 printk(KERN_INFO "sending NMI to all CPUs:\n");
50 apic->send_IPI_all(NMI_VECTOR);
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)))
59 clear_bit(0, &backtrace_flag);
60 smp_mb__after_clear_bit();
64 arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
68 cpu = smp_processor_id();
70 if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
71 static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
73 arch_spin_lock(&lock);
74 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
76 arch_spin_unlock(&lock);
77 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
84 static int __init register_trigger_all_cpu_backtrace(void)
86 register_nmi_handler(NMI_LOCAL, arch_trigger_all_cpu_backtrace_handler,
90 early_initcall(register_trigger_all_cpu_backtrace);