1 /* 2 * NMI backtrace support 3 * 4 * Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King, 5 * with the following header: 6 * 7 * HW NMI watchdog support 8 * 9 * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. 10 * 11 * Arch specific calls to support NMI watchdog 12 * 13 * Bits copied from original nmi.c file 14 */ 15 #include <linux/cpumask.h> 16 #include <linux/delay.h> 17 #include <linux/kprobes.h> 18 #include <linux/nmi.h> 19 20 #ifdef arch_trigger_all_cpu_backtrace 21 /* For reliability, we're prepared to waste bits here. */ 22 static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; 23 24 /* "in progress" flag of arch_trigger_all_cpu_backtrace */ 25 static unsigned long backtrace_flag; 26 27 /* 28 * When raise() is called it will be is passed a pointer to the 29 * backtrace_mask. Architectures that call nmi_cpu_backtrace() 30 * directly from their raise() functions may rely on the mask 31 * they are passed being updated as a side effect of this call. 32 */ 33 void nmi_trigger_all_cpu_backtrace(bool include_self, 34 void (*raise)(cpumask_t *mask)) 35 { 36 int i, this_cpu = get_cpu(); 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 put_cpu(); 44 return; 45 } 46 47 cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask); 48 if (!include_self) 49 cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask)); 50 51 if (!cpumask_empty(to_cpumask(backtrace_mask))) { 52 pr_info("Sending NMI to %s CPUs:\n", 53 (include_self ? "all" : "other")); 54 raise(to_cpumask(backtrace_mask)); 55 } 56 57 /* Wait for up to 10 seconds for all CPUs to do the backtrace */ 58 for (i = 0; i < 10 * 1000; i++) { 59 if (cpumask_empty(to_cpumask(backtrace_mask))) 60 break; 61 mdelay(1); 62 touch_softlockup_watchdog(); 63 } 64 65 /* 66 * Force flush any remote buffers that might be stuck in IRQ context 67 * and therefore could not run their irq_work. 68 */ 69 printk_nmi_flush(); 70 71 clear_bit_unlock(0, &backtrace_flag); 72 put_cpu(); 73 } 74 75 bool nmi_cpu_backtrace(struct pt_regs *regs) 76 { 77 int cpu = smp_processor_id(); 78 79 if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { 80 pr_warn("NMI backtrace for cpu %d\n", cpu); 81 if (regs) 82 show_regs(regs); 83 else 84 dump_stack(); 85 cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); 86 return true; 87 } 88 89 return false; 90 } 91 NOKPROBE_SYMBOL(nmi_cpu_backtrace); 92 #endif 93