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 103