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Commit | Line | Data |
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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 | #include <linux/cpu.h> | |
20 | #include <linux/sched/debug.h> | |
21 | ||
22 | #ifdef arch_trigger_cpumask_backtrace | |
23 | /* For reliability, we're prepared to waste bits here. */ | |
24 | static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; | |
25 | ||
26 | /* "in progress" flag of arch_trigger_cpumask_backtrace */ | |
27 | static unsigned long backtrace_flag; | |
28 | ||
29 | /* | |
30 | * When raise() is called it will be passed a pointer to the | |
31 | * backtrace_mask. Architectures that call nmi_cpu_backtrace() | |
32 | * directly from their raise() functions may rely on the mask | |
33 | * they are passed being updated as a side effect of this call. | |
34 | */ | |
35 | void nmi_trigger_cpumask_backtrace(const cpumask_t *mask, | |
36 | bool exclude_self, | |
37 | void (*raise)(cpumask_t *mask)) | |
38 | { | |
39 | int i, this_cpu = get_cpu(); | |
40 | ||
41 | if (test_and_set_bit(0, &backtrace_flag)) { | |
42 | /* | |
43 | * If there is already a trigger_all_cpu_backtrace() in progress | |
44 | * (backtrace_flag == 1), don't output double cpu dump infos. | |
45 | */ | |
46 | put_cpu(); | |
47 | return; | |
48 | } | |
49 | ||
50 | cpumask_copy(to_cpumask(backtrace_mask), mask); | |
51 | if (exclude_self) | |
52 | cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask)); | |
53 | ||
54 | /* | |
55 | * Don't try to send an NMI to this cpu; it may work on some | |
56 | * architectures, but on others it may not, and we'll get | |
57 | * information at least as useful just by doing a dump_stack() here. | |
58 | * Note that nmi_cpu_backtrace(NULL) will clear the cpu bit. | |
59 | */ | |
60 | if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask))) | |
61 | nmi_cpu_backtrace(NULL); | |
62 | ||
63 | if (!cpumask_empty(to_cpumask(backtrace_mask))) { | |
64 | pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n", | |
65 | this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask)); | |
66 | raise(to_cpumask(backtrace_mask)); | |
67 | } | |
68 | ||
69 | /* Wait for up to 10 seconds for all CPUs to do the backtrace */ | |
70 | for (i = 0; i < 10 * 1000; i++) { | |
71 | if (cpumask_empty(to_cpumask(backtrace_mask))) | |
72 | break; | |
73 | mdelay(1); | |
74 | touch_softlockup_watchdog(); | |
75 | } | |
76 | ||
77 | /* | |
78 | * Force flush any remote buffers that might be stuck in IRQ context | |
79 | * and therefore could not run their irq_work. | |
80 | */ | |
81 | printk_safe_flush(); | |
82 | ||
83 | clear_bit_unlock(0, &backtrace_flag); | |
84 | put_cpu(); | |
85 | } | |
86 | ||
87 | bool nmi_cpu_backtrace(struct pt_regs *regs) | |
88 | { | |
89 | static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED; | |
90 | int cpu = smp_processor_id(); | |
91 | ||
92 | if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { | |
93 | arch_spin_lock(&lock); | |
94 | if (regs && cpu_in_idle(instruction_pointer(regs))) { | |
95 | pr_warn("NMI backtrace for cpu %d skipped: idling at pc %#lx\n", | |
96 | cpu, instruction_pointer(regs)); | |
97 | } else { | |
98 | pr_warn("NMI backtrace for cpu %d\n", cpu); | |
99 | if (regs) | |
100 | show_regs(regs); | |
101 | else | |
102 | dump_stack(); | |
103 | } | |
104 | arch_spin_unlock(&lock); | |
105 | cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); | |
106 | return true; | |
107 | } | |
108 | ||
109 | return false; | |
110 | } | |
111 | NOKPROBE_SYMBOL(nmi_cpu_backtrace); | |
112 | #endif |