linux-imx

// 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.

         */

        put_cpu();

        return;

    }

​

    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)))

        nmi_cpu_backtrace(NULL);

​