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