xref: /openbmc/linux/arch/x86/kernel/apic/hw_nmi.c (revision e23feb16)
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
92