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b2c0b2cb RK |
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> | |
b2c0b2cb | 19 | |
9a01c3ed | 20 | #ifdef arch_trigger_cpumask_backtrace |
b2c0b2cb RK |
21 | /* For reliability, we're prepared to waste bits here. */ |
22 | static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; | |
b2c0b2cb | 23 | |
9a01c3ed | 24 | /* "in progress" flag of arch_trigger_cpumask_backtrace */ |
b2c0b2cb RK |
25 | static unsigned long backtrace_flag; |
26 | ||
0768330d | 27 | /* |
9a01c3ed | 28 | * When raise() is called it will be passed a pointer to the |
0768330d DT |
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 | */ | |
9a01c3ed CM |
33 | void nmi_trigger_cpumask_backtrace(const cpumask_t *mask, |
34 | bool exclude_self, | |
b2c0b2cb RK |
35 | void (*raise)(cpumask_t *mask)) |
36 | { | |
42a0bb3f | 37 | int i, this_cpu = get_cpu(); |
b2c0b2cb RK |
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 | put_cpu(); | |
45 | return; | |
46 | } | |
47 | ||
9a01c3ed CM |
48 | cpumask_copy(to_cpumask(backtrace_mask), mask); |
49 | if (exclude_self) | |
b2c0b2cb RK |
50 | cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask)); |
51 | ||
67766489 CM |
52 | /* |
53 | * Don't try to send an NMI to this cpu; it may work on some | |
54 | * architectures, but on others it may not, and we'll get | |
55 | * information at least as useful just by doing a dump_stack() here. | |
56 | * Note that nmi_cpu_backtrace(NULL) will clear the cpu bit. | |
57 | */ | |
58 | if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask))) | |
59 | nmi_cpu_backtrace(NULL); | |
60 | ||
b2c0b2cb | 61 | if (!cpumask_empty(to_cpumask(backtrace_mask))) { |
9a01c3ed CM |
62 | pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n", |
63 | this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask)); | |
b2c0b2cb RK |
64 | raise(to_cpumask(backtrace_mask)); |
65 | } | |
66 | ||
67 | /* Wait for up to 10 seconds for all CPUs to do the backtrace */ | |
68 | for (i = 0; i < 10 * 1000; i++) { | |
69 | if (cpumask_empty(to_cpumask(backtrace_mask))) | |
70 | break; | |
71 | mdelay(1); | |
72 | touch_softlockup_watchdog(); | |
73 | } | |
74 | ||
75 | /* | |
42a0bb3f PM |
76 | * Force flush any remote buffers that might be stuck in IRQ context |
77 | * and therefore could not run their irq_work. | |
b2c0b2cb | 78 | */ |
42a0bb3f | 79 | printk_nmi_flush(); |
b2c0b2cb | 80 | |
42a0bb3f | 81 | clear_bit_unlock(0, &backtrace_flag); |
b2c0b2cb RK |
82 | put_cpu(); |
83 | } | |
84 | ||
b2c0b2cb RK |
85 | bool nmi_cpu_backtrace(struct pt_regs *regs) |
86 | { | |
87 | int cpu = smp_processor_id(); | |
88 | ||
89 | if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { | |
b2c0b2cb | 90 | pr_warn("NMI backtrace for cpu %d\n", cpu); |
0768330d DT |
91 | if (regs) |
92 | show_regs(regs); | |
93 | else | |
94 | dump_stack(); | |
b2c0b2cb RK |
95 | cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); |
96 | return true; | |
97 | } | |
98 | ||
99 | return false; | |
100 | } | |
101 | NOKPROBE_SYMBOL(nmi_cpu_backtrace); | |
102 | #endif |