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 20 #ifdef CONFIG_HARDLOCKUP_DETECTOR 21 u64 hw_nmi_get_sample_period(void) 22 { 23 return (u64)(cpu_khz) * 1000 * 60; 24 } 25 #endif 26 27 #ifdef arch_trigger_all_cpu_backtrace 28 /* For reliability, we're prepared to waste bits here. */ 29 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; 30 31 /* "in progress" flag of arch_trigger_all_cpu_backtrace */ 32 static unsigned long backtrace_flag; 33 34 void arch_trigger_all_cpu_backtrace(void) 35 { 36 int i; 37 38 if (test_and_set_bit(0, &backtrace_flag)) 39 /* 40 * If there is already a trigger_all_cpu_backtrace() in progress 41 * (backtrace_flag == 1), don't output double cpu dump infos. 42 */ 43 return; 44 45 cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask); 46 47 printk(KERN_INFO "sending NMI to all CPUs:\n"); 48 apic->send_IPI_all(NMI_VECTOR); 49 50 /* Wait for up to 10 seconds for all CPUs to do the backtrace */ 51 for (i = 0; i < 10 * 1000; i++) { 52 if (cpumask_empty(to_cpumask(backtrace_mask))) 53 break; 54 mdelay(1); 55 } 56 57 clear_bit(0, &backtrace_flag); 58 smp_mb__after_clear_bit(); 59 } 60 61 static int __kprobes 62 arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self, 63 unsigned long cmd, void *__args) 64 { 65 struct die_args *args = __args; 66 struct pt_regs *regs; 67 int cpu; 68 69 switch (cmd) { 70 case DIE_NMI: 71 break; 72 73 default: 74 return NOTIFY_DONE; 75 } 76 77 regs = args->regs; 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 dump_stack(); 87 arch_spin_unlock(&lock); 88 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); 89 return NOTIFY_STOP; 90 } 91 92 return NOTIFY_DONE; 93 } 94 95 static __read_mostly struct notifier_block backtrace_notifier = { 96 .notifier_call = arch_trigger_all_cpu_backtrace_handler, 97 .next = NULL, 98 .priority = NMI_LOCAL_LOW_PRIOR, 99 }; 100 101 static int __init register_trigger_all_cpu_backtrace(void) 102 { 103 register_die_notifier(&backtrace_notifier); 104 return 0; 105 } 106 early_initcall(register_trigger_all_cpu_backtrace); 107 #endif 108