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121 lines
3.3 KiB
121 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* NMI backtrace support |
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* |
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* Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King, |
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* with the following header: |
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* |
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* HW NMI watchdog support |
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* |
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* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. |
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* |
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* Arch specific calls to support NMI watchdog |
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* |
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* Bits copied from original nmi.c file |
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*/ |
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#include <linux/cpumask.h> |
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#include <linux/delay.h> |
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#include <linux/kprobes.h> |
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#include <linux/nmi.h> |
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#include <linux/cpu.h> |
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#include <linux/sched/debug.h> |
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#ifdef arch_trigger_cpumask_backtrace |
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/* For reliability, we're prepared to waste bits here. */ |
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static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; |
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/* "in progress" flag of arch_trigger_cpumask_backtrace */ |
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static unsigned long backtrace_flag; |
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/* |
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* When raise() is called it will be passed a pointer to the |
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* backtrace_mask. Architectures that call nmi_cpu_backtrace() |
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* directly from their raise() functions may rely on the mask |
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* they are passed being updated as a side effect of this call. |
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*/ |
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void nmi_trigger_cpumask_backtrace(const cpumask_t *mask, |
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bool exclude_self, |
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void (*raise)(cpumask_t *mask)) |
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{ |
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int i, this_cpu = get_cpu(); |
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if (test_and_set_bit(0, &backtrace_flag)) { |
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/* |
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* If there is already a trigger_all_cpu_backtrace() in progress |
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* (backtrace_flag == 1), don't output double cpu dump infos. |
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*/ |
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put_cpu(); |
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return; |
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} |
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cpumask_copy(to_cpumask(backtrace_mask), mask); |
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if (exclude_self) |
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cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask)); |
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/* |
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* Don't try to send an NMI to this cpu; it may work on some |
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* architectures, but on others it may not, and we'll get |
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* information at least as useful just by doing a dump_stack() here. |
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* Note that nmi_cpu_backtrace(NULL) will clear the cpu bit. |
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*/ |
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if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask))) |
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nmi_cpu_backtrace(NULL); |
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if (!cpumask_empty(to_cpumask(backtrace_mask))) { |
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pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n", |
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this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask)); |
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raise(to_cpumask(backtrace_mask)); |
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} |
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/* Wait for up to 10 seconds for all CPUs to do the backtrace */ |
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for (i = 0; i < 10 * 1000; i++) { |
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if (cpumask_empty(to_cpumask(backtrace_mask))) |
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break; |
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mdelay(1); |
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touch_softlockup_watchdog(); |
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} |
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/* |
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* Force flush any remote buffers that might be stuck in IRQ context |
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* and therefore could not run their irq_work. |
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*/ |
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printk_trigger_flush(); |
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clear_bit_unlock(0, &backtrace_flag); |
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put_cpu(); |
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} |
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// Dump stacks even for idle CPUs. |
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static bool backtrace_idle; |
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module_param(backtrace_idle, bool, 0644); |
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bool nmi_cpu_backtrace(struct pt_regs *regs) |
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{ |
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int cpu = smp_processor_id(); |
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unsigned long flags; |
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if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { |
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/* |
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* Allow nested NMI backtraces while serializing |
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* against other CPUs. |
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*/ |
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printk_cpu_lock_irqsave(flags); |
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if (!READ_ONCE(backtrace_idle) && regs && cpu_in_idle(instruction_pointer(regs))) { |
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pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n", |
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cpu, (void *)instruction_pointer(regs)); |
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} else { |
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pr_warn("NMI backtrace for cpu %d\n", cpu); |
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if (regs) |
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show_regs(regs); |
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else |
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dump_stack(); |
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} |
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printk_cpu_unlock_irqrestore(flags); |
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cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); |
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return true; |
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} |
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return false; |
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} |
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NOKPROBE_SYMBOL(nmi_cpu_backtrace); |
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#endif
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