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 /* For reliability, we're prepared to waste bits here. */ 30 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; 31 32 /* "in progress" flag of arch_trigger_all_cpu_backtrace */ 33 static unsigned long backtrace_flag; 34 35 void arch_trigger_all_cpu_backtrace(void) 36 { 37 int i; 38 39 if (test_and_set_bit(0, &backtrace_flag)) 40 /* 41 * If there is already a trigger_all_cpu_backtrace() in progress 42 * (backtrace_flag == 1), don't output double cpu dump infos. 43 */ 44 return; 45 46 cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask); 47 48 printk(KERN_INFO "sending NMI to all CPUs:\n"); 49 apic->send_IPI_all(NMI_VECTOR); 50 51 /* Wait for up to 10 seconds for all CPUs to do the backtrace */ 52 for (i = 0; i < 10 * 1000; i++) { 53 if (cpumask_empty(to_cpumask(backtrace_mask))) 54 break; 55 mdelay(1); 56 } 57 58 clear_bit(0, &backtrace_flag); 59 smp_mb__after_clear_bit(); 60 } 61 62 static int __kprobes 63 arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs) 64 { 65 int cpu; 66 67 cpu = smp_processor_id(); 68 69 if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { 70 static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED; 71 72 arch_spin_lock(&lock); 73 printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu); 74 show_regs(regs); 75 arch_spin_unlock(&lock); 76 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); 77 return NMI_HANDLED; 78 } 79 80 return NMI_DONE; 81 } 82 83 static int __init register_trigger_all_cpu_backtrace(void) 84 { 85 register_nmi_handler(NMI_LOCAL, arch_trigger_all_cpu_backtrace_handler, 86 0, "arch_bt"); 87 return 0; 88 } 89 early_initcall(register_trigger_all_cpu_backtrace); 90 #endif 91