path: root/kernel/panic.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/kernel/panic.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * This function is used through-out the kernel (including mm and fs)
 * to indicate a major problem.
 */
#include <linux/debug_locks.h>
#include <linux/sched/debug.h>
#include <linux/interrupt.h>
#include <linux/kgdb.h>
#include <linux/kmsg_dump.h>
#include <linux/kallsyms.h>
#include <linux/notifier.h>
#include <linux/vt_kern.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/ftrace.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/kexec.h>
#include <linux/panic_notifier.h>
#include <linux/sched.h>
#include <linux/string_helpers.h>
#include <linux/sysrq.h>
#include <linux/init.h>
#include <linux/nmi.h>
#include <linux/console.h>
#include <linux/bug.h>
#include <linux/ratelimit.h>
#include <linux/debugfs.h>
#include <linux/sysfs.h>
#include <linux/context_tracking.h>
#include <linux/seq_buf.h>
#include <linux/sys_info.h>
#include <trace/events/error_report.h>
#include <asm/sections.h>

#define PANIC_TIMER_STEP 100
#define PANIC_BLINK_SPD 18

#ifdef CONFIG_SMP
/*
 * Should we dump all CPUs backtraces in an oops event?
 * Defaults to 0, can be changed via sysctl.
 */
static unsigned int __read_mostly sysctl_oops_all_cpu_backtrace;
#else
#define sysctl_oops_all_cpu_backtrace 0
#endif /* CONFIG_SMP */

int panic_on_oops = IS_ENABLED(CONFIG_PANIC_ON_OOPS);
static unsigned long tainted_mask =
	IS_ENABLED(CONFIG_RANDSTRUCT) ? (1 << TAINT_RANDSTRUCT) : 0;
static int pause_on_oops;
static int pause_on_oops_flag;
static DEFINE_SPINLOCK(pause_on_oops_lock);
bool crash_kexec_post_notifiers;
int panic_on_warn __read_mostly;
unsigned long panic_on_taint;
bool panic_on_taint_nousertaint = false;
static unsigned int warn_limit __read_mostly;
static bool panic_console_replay;

bool panic_triggering_all_cpu_backtrace;
static bool panic_this_cpu_backtrace_printed;

int panic_timeout = CONFIG_PANIC_TIMEOUT;
EXPORT_SYMBOL_GPL(panic_timeout);

unsigned long panic_print;

ATOMIC_NOTIFIER_HEAD(panic_notifier_list);

EXPORT_SYMBOL(panic_notifier_list);

static void panic_print_deprecated(void)
{
	pr_info_once("Kernel: The 'panic_print' parameter is now deprecated. Please use 'panic_sys_info' and 'panic_console_replay' instead.\n");
}

#ifdef CONFIG_SYSCTL

/*
 * Taint values can only be increased
 * This means we can safely use a temporary.
 */
static int proc_taint(const struct ctl_table *table, int write,
			       void *buffer, size_t *lenp, loff_t *ppos)
{
	struct ctl_table t;
	unsigned long tmptaint = get_taint();
	int err;

	if (write && !capable(CAP_SYS_ADMIN))
		return -EPERM;

	t = *table;
	t.data = &tmptaint;
	err = proc_doulongvec_minmax(&t, write, buffer, lenp, ppos);
	if (err < 0)
		return err;

	if (write) {
		int i;

		/*
		 * If we are relying on panic_on_taint not producing
		 * false positives due to userspace input, bail out
		 * before setting the requested taint flags.
		 */
		if (panic_on_taint_nousertaint && (tmptaint & panic_on_taint))
			return -EINVAL;

		/*
		 * Poor man's atomic or. Not worth adding a primitive
		 * to everyone's atomic.h for this
		 */
		for (i = 0; i < TAINT_FLAGS_COUNT; i++)
			if ((1UL << i) & tmptaint)
				add_taint(i, LOCKDEP_STILL_OK);
	}

	return err;
}

static int sysctl_panic_print_handler(const struct ctl_table *table, int write,
			   void *buffer, size_t *lenp, loff_t *ppos)
{
	panic_print_deprecated();
	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
}

static const struct ctl_table kern_panic_table[] = {
#ifdef CONFIG_SMP
	{
		.procname       = "oops_all_cpu_backtrace",
		.data           = &sysctl_oops_all_cpu_backtrace,
		.maxlen         = sizeof(int),
		.mode           = 0644,
		.proc_handler   = proc_dointvec_minmax,
		.extra1         = SYSCTL_ZERO,
		.extra2         = SYSCTL_ONE,
	},
#endif
	{
		.procname	= "tainted",
		.maxlen		= sizeof(long),
		.mode		= 0644,
		.proc_handler