blob: 70b1f9d830cda984c4801abd0278f4b2528a02fa [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
* NMI backtrace support
* Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King,
* with the following header:
* HW NMI watchdog support
* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
* Arch specific calls to support NMI watchdog
* Bits copied from original nmi.c file
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/kprobes.h>
#include <linux/nmi.h>
#include <linux/cpu.h>
#include <linux/sched/debug.h>
#ifdef arch_trigger_cpumask_backtrace
/* For reliability, we're prepared to waste bits here. */
static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
/* "in progress" flag of arch_trigger_cpumask_backtrace */
static unsigned long backtrace_flag;
* When raise() is called it will be passed a pointer to the
* backtrace_mask. Architectures that call nmi_cpu_backtrace()
* directly from their raise() functions may rely on the mask
* they are passed being updated as a side effect of this call.
void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
bool exclude_self,
void (*raise)(cpumask_t *mask))
int i, this_cpu = get_cpu();
if (test_and_set_bit(0, &backtrace_flag)) {
* If there is already a trigger_all_cpu_backtrace() in progress
* (backtrace_flag == 1), don't output double cpu dump infos.
cpumask_copy(to_cpumask(backtrace_mask), mask);
if (exclude_self)
cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
* Don't try to send an NMI to this cpu; it may work on some
* architectures, but on others it may not, and we'll get
* information at least as useful just by doing a dump_stack() here.
* Note that nmi_cpu_backtrace(NULL) will clear the cpu bit.
if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask)))
if (!cpumask_empty(to_cpumask(backtrace_mask))) {
pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n",
this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask));
/* Wait for up to 10 seconds for all CPUs to do the backtrace */
for (i = 0; i < 10 * 1000; i++) {
if (cpumask_empty(to_cpumask(backtrace_mask)))
* Force flush any remote buffers that might be stuck in IRQ context
* and therefore could not run their irq_work.
clear_bit_unlock(0, &backtrace_flag);
bool nmi_cpu_backtrace(struct pt_regs *regs)
int cpu = smp_processor_id();
if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
if (regs && cpu_in_idle(instruction_pointer(regs))) {
pr_warn("NMI backtrace for cpu %d skipped: idling at pc %#lx\n",
cpu, instruction_pointer(regs));
} else {
pr_warn("NMI backtrace for cpu %d\n", cpu);
if (regs)
cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
return true;
return false;