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