| 1 | |
| 2 | |
| 3 | * NMI backtrace support
|
| 4 | *
|
| 5 | * Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King,
|
| 6 | * with the following header:
|
| 7 | *
|
| 8 | * HW NMI watchdog support
|
| 9 | *
|
| 10 | * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
|
| 11 | *
|
| 12 | * Arch specific calls to support NMI watchdog
|
| 13 | *
|
| 14 | * Bits copied from original nmi.c file
|
| 15 |
|
| 16 | #include <linux/cpumask.h>
|
| 17 | #include <linux/delay.h>
|
| 18 | #include <linux/kprobes.h>
|
| 19 | #include <linux/nmi.h>
|
| 20 | #include <linux/cpu.h>
|
| 21 | #include <linux/sched/debug.h>
|
| 22 |
|
| 23 | #ifdef arch_trigger_cpumask_backtrace
|
| 24 |
|
| 25 | static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
|
| 26 |
|
| 27 |
|
| 28 | static unsigned long backtrace_flag;
|
| 29 |
|
| 30 | |
| 31 | * When raise() is called it will be passed a pointer to the
|
| 32 | * backtrace_mask. Architectures that call nmi_cpu_backtrace()
|
| 33 | * directly from their raise() functions may rely on the mask
|
| 34 | * they are passed being updated as a side effect of this call.
|
| 35 |
|
| 36 | void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
|
| 37 | bool exclude_self,
|
| 38 | void (*raise)(cpumask_t *mask))
|
| 39 | {
|
| 40 | int i, this_cpu = get_cpu();
|
| 41 |
|
| 42 | if (test_and_set_bit(0, &backtrace_flag)) {
|
| 43 | |
| 44 | * If there is already a trigger_all_cpu_backtrace() in progress
|
| 45 | * (backtrace_flag == 1), don't output double cpu dump infos.
|
| 46 |
|
| 47 | put_cpu();
|
| 48 | return;
|
| 49 | }
|
| 50 |
|
| 51 | cpumask_copy(to_cpumask(backtrace_mask), mask);
|
| 52 | if (exclude_self)
|
| 53 | cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
|
| 54 |
|
| 55 | |
| 56 | * Don't try to send an NMI to this cpu; it may work on some
|
| 57 | * architectures, but on others it may not, and we'll get
|
| 58 | * information at least as useful just by doing a dump_stack() here.
|
| 59 | * Note that nmi_cpu_backtrace(NULL) will clear the cpu bit.
|
| 60 |
|
| 61 | if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask)))
|
| 62 | nmi_cpu_backtrace(NULL);
|
| 63 |
|
| 64 | if (!cpumask_empty(to_cpumask(backtrace_mask))) {
|
| 65 | pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n",
|
| 66 | this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask));
|
| 67 | raise(to_cpumask(backtrace_mask));
|
| 68 | }
|
| 69 |
|
| 70 |
|
| 71 | for (i = 0; i < 10 * 1000; i++) {
|
| 72 | if (cpumask_empty(to_cpumask(backtrace_mask)))
|
| 73 | break;
|
| 74 | mdelay(1);
|
| 75 | touch_softlockup_watchdog();
|
| 76 | }
|
| 77 |
|
| 78 | |
| 79 | * Force flush any remote buffers that might be stuck in IRQ context
|
| 80 | * and therefore could not run their irq_work.
|
| 81 |
|
| 82 | printk_trigger_flush();
|
| 83 |
|
| 84 | clear_bit_unlock(0, &backtrace_flag);
|
| 85 | put_cpu();
|
| 86 | }
|
| 87 |
|
| 88 | |
| 89 | static bool backtrace_idle;
|
| 90 | module_param(backtrace_idle, bool, 0644);
|
| 91 |
|
| 92 | bool nmi_cpu_backtrace(struct pt_regs *regs)
|
| 93 | {
|
| 94 | int cpu = smp_processor_id();
|
| 95 | unsigned long flags;
|
| 96 |
|
| 97 | if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
|
| 98 | |
| 99 | * Allow nested NMI backtraces while serializing
|
| 100 | * against other CPUs.
|
| 101 |
|
| 102 | printk_cpu_sync_get_irqsave(flags);
|
| 103 | if (!READ_ONCE(backtrace_idle) && regs && cpu_in_idle(instruction_pointer(regs))) {
|
| 104 | pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n",
|
| 105 | cpu, (void *)instruction_pointer(regs));
|
| 106 | } else {
|
| 107 | pr_warn("NMI backtrace for cpu %d\n", cpu);
|
| 108 | if (regs)
|
| 109 | show_regs(regs);
|
| 110 | else
|
| 111 | dump_stack();
|
| 112 | }
|
| 113 | printk_cpu_sync_put_irqrestore(flags);
|
| 114 | cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
|
| 115 | return true;
|
| 116 | }
|
| 117 |
|
| 118 | return false;
|
| 119 | }
|
| 120 | NOKPROBE_SYMBOL(nmi_cpu_backtrace);
|
| 121 | #endif
|