kernel/panic.c - kernel/msm-4.9 - Gitiles

 /*
  *  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/interrupt.h>
 #include <linux/kmsg_dump.h>
 #include <linux/kallsyms.h>
 #include <linux/notifier.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/sched.h>
 #include <linux/sysrq.h>
 #include <linux/init.h>
 #include <linux/nmi.h>

 #define PANIC_TIMER_STEP 100
 #define PANIC_BLINK_SPD 18

 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
 static unsigned long tainted_mask;
 static int pause_on_oops;
 static int pause_on_oops_flag;
 static DEFINE_SPINLOCK(pause_on_oops_lock);
 static bool crash_kexec_post_notifiers;

 int panic_timeout = CONFIG_PANIC_TIMEOUT;
 EXPORT_SYMBOL_GPL(panic_timeout);

 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);

 EXPORT_SYMBOL(panic_notifier_list);

 static long no_blink(int state)
 {
 	return 0;
 }

 /* Returns how long it waited in ms */
 long (*panic_blink)(int state);
 EXPORT_SYMBOL(panic_blink);

 /*
  * Stop ourself in panic -- architecture code may override this
  */
 void __weak panic_smp_self_stop(void)
 {
 	while (1)
 		cpu_relax();
 }

 /**
  *	panic - halt the system
  *	@fmt: The text string to print
  *
  *	Display a message, then perform cleanups.
  *
  *	This function never returns.
  */
 void panic(const char *fmt, ...)
 {
 	static DEFINE_SPINLOCK(panic_lock);
 	static char buf[1024];
 	va_list args;
 	long i, i_next = 0;
 	int state = 0;

 	/*
 	 * Disable local interrupts. This will prevent panic_smp_self_stop
 	 * from deadlocking the first cpu that invokes the panic, since
 	 * there is nothing to prevent an interrupt handler (that runs
 	 * after the panic_lock is acquired) from invoking panic again.
 	 */
 	local_irq_disable();

 	/*
 	 * It's possible to come here directly from a panic-assertion and
 	 * not have preempt disabled. Some functions called from here want
 	 * preempt to be disabled. No point enabling it later though...
 	 *
 	 * Only one CPU is allowed to execute the panic code from here. For
 	 * multiple parallel invocations of panic, all other CPUs either
 	 * stop themself or will wait until they are stopped by the 1st CPU
 	 * with smp_send_stop().
 	 */
 	if (!spin_trylock(&panic_lock))
 		panic_smp_self_stop();

 	console_verbose();
 	bust_spinlocks(1);
 	va_start(args, fmt);
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 	pr_emerg("Kernel panic - not syncing: %s\n", buf);
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 	/*
 	 * Avoid nested stack-dumping if a panic occurs during oops processing
 	 */
 	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
 		dump_stack();
 #endif

 	/*
 	 * If we have crashed and we have a crash kernel loaded let it handle
 	 * everything else.
 	 * If we want to run this after calling panic_notifiers, pass
 	 * the "crash_kexec_post_notifiers" option to the kernel.
 	 */
 	if (!crash_kexec_post_notifiers)
 		crash_kexec(NULL);

 	/*
 	 * Note smp_send_stop is the usual smp shutdown function, which
 	 * unfortunately means it may not be hardened to work in a panic
 	 * situation.
 	 */
 	smp_send_stop();

 	/*
 	 * Run any panic handlers, including those that might need to
 	 * add information to the kmsg dump output.
 	 */
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);

 	kmsg_dump(KMSG_DUMP_PANIC);

 	/*
 	 * If you doubt kdump always works fine in any situation,
 	 * "crash_kexec_post_notifiers" offers you a chance to run
 	 * panic_notifiers and dumping kmsg before kdump.
 	 * Note: since some panic_notifiers can make crashed kernel
 	 * more unstable, it can increase risks of the kdump failure too.
 	 */
 	crash_kexec(NULL);

 	bust_spinlocks(0);

 	if (!panic_blink)
 		panic_blink = no_blink;

 	if (panic_timeout > 0) {
 		/*
 		 * Delay timeout seconds before rebooting the machine.
 		 * We can't use the "normal" timers since we just panicked.
 		 */
 		pr_emerg("Rebooting in %d seconds..", panic_timeout);

 		for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
 			touch_nmi_watchdog();
 			if (i >= i_next) {
 				i += panic_blink(state ^= 1);
 				i_next = i + 3600 / PANIC_BLINK_SPD;
 			}
 			mdelay(PANIC_TIMER_STEP);
 		}
 	}
 	if (panic_timeout != 0) {
 		/*
 		 * This will not be a clean reboot, with everything
 		 * shutting down.  But if there is a chance of
 		 * rebooting the system it will be rebooted.
 		 */
 		emergency_restart();
 	}
 #ifdef __sparc__
 	{
 		extern int stop_a_enabled;
 		/* Make sure the user can actually press Stop-A (L1-A) */
 		stop_a_enabled = 1;
 		pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
 	}
 #endif
 #if defined(CONFIG_S390)
 	{
 		unsigned long caller;

 		caller = (unsigned long)__builtin_return_address(0);
 		disabled_wait(caller);
 	}
 #endif
 	pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
 	local_irq_enable();
 	for (i = 0; ; i += PANIC_TIMER_STEP) {
 		touch_softlockup_watchdog();
 		if (i >= i_next) {
 			i += panic_blink(state ^= 1);
 			i_next = i + 3600 / PANIC_BLINK_SPD;
 		}
 		mdelay(PANIC_TIMER_STEP);
 	}
 }

 EXPORT_SYMBOL(panic);


 struct tnt {
 	u8	bit;
 	char	true;
 	char	false;
 };

 static const struct tnt tnts[] = {
 	{ TAINT_PROPRIETARY_MODULE,	'P', 'G' },
 	{ TAINT_FORCED_MODULE,		'F', ' ' },
 	{ TAINT_CPU_OUT_OF_SPEC,	'S', ' ' },
 	{ TAINT_FORCED_RMMOD,		'R', ' ' },
 	{ TAINT_MACHINE_CHECK,		'M', ' ' },
 	{ TAINT_BAD_PAGE,		'B', ' ' },
 	{ TAINT_USER,			'U', ' ' },
 	{ TAINT_DIE,			'D', ' ' },
 	{ TAINT_OVERRIDDEN_ACPI_TABLE,	'A', ' ' },
 	{ TAINT_WARN,			'W', ' ' },
 	{ TAINT_CRAP,			'C', ' ' },
 	{ TAINT_FIRMWARE_WORKAROUND,	'I', ' ' },
 	{ TAINT_OOT_MODULE,		'O', ' ' },
 	{ TAINT_UNSIGNED_MODULE,	'E', ' ' },
 	{ TAINT_SOFTLOCKUP,		'L', ' ' },
 };

 /**
  *	print_tainted - return a string to represent the kernel taint state.
  *
  *  'P' - Proprietary module has been loaded.
  *  'F' - Module has been forcibly loaded.
  *  'S' - SMP with CPUs not designed for SMP.
  *  'R' - User forced a module unload.
  *  'M' - System experienced a machine check exception.
  *  'B' - System has hit bad_page.
  *  'U' - Userspace-defined naughtiness.
  *  'D' - Kernel has oopsed before
  *  'A' - ACPI table overridden.
  *  'W' - Taint on warning.
  *  'C' - modules from drivers/staging are loaded.
  *  'I' - Working around severe firmware bug.
  *  'O' - Out-of-tree module has been loaded.
  *  'E' - Unsigned module has been loaded.
  *
  *	The string is overwritten by the next call to print_tainted().
  */
 const char *print_tainted(void)
 {
 	static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];

 	if (tainted_mask) {
 		char *s;
 		int i;

 		s = buf + sprintf(buf, "Tainted: ");
 		for (i = 0; i < ARRAY_SIZE(tnts); i++) {
 			const struct tnt *t = &tnts[i];
 			*s++ = test_bit(t->bit, &tainted_mask) ?
 					t->true : t->false;
 		}
 		*s = 0;
 	} else
 		snprintf(buf, sizeof(buf), "Not tainted");

 	return buf;
 }

 int test_taint(unsigned flag)
 {
 	return test_bit(flag, &tainted_mask);
 }
 EXPORT_SYMBOL(test_taint);

 unsigned long get_taint(void)
 {
 	return tainted_mask;
 }

 /**
  * add_taint: add a taint flag if not already set.
  * @flag: one of the TAINT_* constants.
  * @lockdep_ok: whether lock debugging is still OK.
  *
  * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
  * some notewortht-but-not-corrupting cases, it can be set to true.
  */
 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
 {
 	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
 		pr_warn("Disabling lock debugging due to kernel taint\n");

 	set_bit(flag, &tainted_mask);
 }
 EXPORT_SYMBOL(add_taint);

 static void spin_msec(int msecs)
 {
 	int i;

 	for (i = 0; i < msecs; i++) {
 		touch_nmi_watchdog();
 		mdelay(1);
 	}
 }

 /*
  * It just happens that oops_enter() and oops_exit() are identically
  * implemented...
  */
 static void do_oops_enter_exit(void)
 {
 	unsigned long flags;
 	static int spin_counter;

 	if (!pause_on_oops)
 		return;

 	spin_lock_irqsave(&pause_on_oops_lock, flags);
 	if (pause_on_oops_flag == 0) {
 		/* This CPU may now print the oops message */
 		pause_on_oops_flag = 1;
 	} else {
 		/* We need to stall this CPU */
 		if (!spin_counter) {
 			/* This CPU gets to do the counting */
 			spin_counter = pause_on_oops;
 			do {
 				spin_unlock(&pause_on_oops_lock);
 				spin_msec(MSEC_PER_SEC);
 				spin_lock(&pause_on_oops_lock);
 			} while (--spin_counter);
 			pause_on_oops_flag = 0;
 		} else {
 			/* This CPU waits for a different one */
 			while (spin_counter) {
 				spin_unlock(&pause_on_oops_lock);
 				spin_msec(1);
 				spin_lock(&pause_on_oops_lock);
 			}
 		}
 	}
 	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
 }

 /*
  * Return true if the calling CPU is allowed to print oops-related info.
  * This is a bit racy..
  */
 int oops_may_print(void)
 {
 	return pause_on_oops_flag == 0;
 }

 /*
  * Called when the architecture enters its oops handler, before it prints
  * anything.  If this is the first CPU to oops, and it's oopsing the first
  * time then let it proceed.
  *
  * This is all enabled by the pause_on_oops kernel boot option.  We do all
  * this to ensure that oopses don't scroll off the screen.  It has the
  * side-effect of preventing later-oopsing CPUs from mucking up the display,
  * too.
  *
  * It turns out that the CPU which is allowed to print ends up pausing for
  * the right duration, whereas all the other CPUs pause for twice as long:
  * once in oops_enter(), once in oops_exit().
  */
 void oops_enter(void)
 {
 	tracing_off();
 	/* can't trust the integrity of the kernel anymore: */
 	debug_locks_off();
 	do_oops_enter_exit();
 }

 /*
  * 64-bit random ID for oopses:
  */
 static u64 oops_id;

 static int init_oops_id(void)
 {
 	if (!oops_id)
 		get_random_bytes(&oops_id, sizeof(oops_id));
 	else
 		oops_id++;

 	return 0;
 }
 late_initcall(init_oops_id);

 void print_oops_end_marker(void)
 {
 	init_oops_id();
 	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
 }

 /*
  * Called when the architecture exits its oops handler, after printing
  * everything.
  */
 void oops_exit(void)
 {
 	do_oops_enter_exit();
 	print_oops_end_marker();
 	kmsg_dump(KMSG_DUMP_OOPS);
 }

 #ifdef WANT_WARN_ON_SLOWPATH
 struct slowpath_args {
 	const char *fmt;
 	va_list args;
 };

 static void warn_slowpath_common(const char *file, int line, void *caller,
 				 unsigned taint, struct slowpath_args *args)
 {
 	disable_trace_on_warning();

 	pr_warn("------------[ cut here ]------------\n");
 	pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
 		raw_smp_processor_id(), current->pid, file, line, caller);

 	if (args)
 		vprintk(args->fmt, args->args);

 	print_modules();
 	dump_stack();
 	print_oops_end_marker();
 	/* Just a warning, don't kill lockdep. */
 	add_taint(taint, LOCKDEP_STILL_OK);
 }

 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 {
 	struct slowpath_args args;

 	args.fmt = fmt;
 	va_start(args.args, fmt);
 	warn_slowpath_common(file, line, __builtin_return_address(0),
 			     TAINT_WARN, &args);
 	va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt);

 void warn_slowpath_fmt_taint(const char *file, int line,
 			     unsigned taint, const char *fmt, ...)
 {
 	struct slowpath_args args;

 	args.fmt = fmt;
 	va_start(args.args, fmt);
 	warn_slowpath_common(file, line, __builtin_return_address(0),
 			     taint, &args);
 	va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt_taint);

 void warn_slowpath_null(const char *file, int line)
 {
 	warn_slowpath_common(file, line, __builtin_return_address(0),
 			     TAINT_WARN, NULL);
 }
 EXPORT_SYMBOL(warn_slowpath_null);
 #endif

 #ifdef CONFIG_CC_STACKPROTECTOR

 /*
  * Called when gcc's -fstack-protector feature is used, and
  * gcc detects corruption of the on-stack canary value
  */
 __visible void __stack_chk_fail(void)
 {
 	panic("stack-protector: Kernel stack is corrupted in: %p\n",
 		__builtin_return_address(0));
 }
 EXPORT_SYMBOL(__stack_chk_fail);

 #endif

 core_param(panic, panic_timeout, int, 0644);
 core_param(pause_on_oops, pause_on_oops, int, 0644);

 static int __init setup_crash_kexec_post_notifiers(char *s)
 {
 	crash_kexec_post_notifiers = true;
 	return 0;
 }
 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);

 static int __init oops_setup(char *s)
 {
 	if (!s)
 		return -EINVAL;
 	if (!strcmp(s, "panic"))
 		panic_on_oops = 1;
 	return 0;
 }
 early_param("oops", oops_setup);
	/*
	* 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/interrupt.h>
	#include <linux/kmsg_dump.h>
	#include <linux/kallsyms.h>
	#include <linux/notifier.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/sched.h>
	#include <linux/sysrq.h>
	#include <linux/init.h>
	#include <linux/nmi.h>

	#define PANIC_TIMER_STEP 100
	#define PANIC_BLINK_SPD 18

	int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
	static unsigned long tainted_mask;
	static int pause_on_oops;
	static int pause_on_oops_flag;
	static DEFINE_SPINLOCK(pause_on_oops_lock);
	static bool crash_kexec_post_notifiers;

	int panic_timeout = CONFIG_PANIC_TIMEOUT;
	EXPORT_SYMBOL_GPL(panic_timeout);

	ATOMIC_NOTIFIER_HEAD(panic_notifier_list);

	EXPORT_SYMBOL(panic_notifier_list);

	static long no_blink(int state)
	{
	return 0;
	}

	/* Returns how long it waited in ms */
	long (*panic_blink)(int state);
	EXPORT_SYMBOL(panic_blink);

	/*
	* Stop ourself in panic -- architecture code may override this
	*/
	void __weak panic_smp_self_stop(void)
	{
	while (1)
	cpu_relax();
	}

	/**
	* panic - halt the system
	* @fmt: The text string to print
	*
	* Display a message, then perform cleanups.
	*
	* This function never returns.
	*/
	void panic(const char *fmt, ...)
	{
	static DEFINE_SPINLOCK(panic_lock);
	static char buf[1024];
	va_list args;
	long i, i_next = 0;
	int state = 0;

	/*
	* Disable local interrupts. This will prevent panic_smp_self_stop
	* from deadlocking the first cpu that invokes the panic, since
	* there is nothing to prevent an interrupt handler (that runs
	* after the panic_lock is acquired) from invoking panic again.
	*/
	local_irq_disable();

	/*
	* It's possible to come here directly from a panic-assertion and
	* not have preempt disabled. Some functions called from here want
	* preempt to be disabled. No point enabling it later though...
	*
	* Only one CPU is allowed to execute the panic code from here. For
	* multiple parallel invocations of panic, all other CPUs either
	* stop themself or will wait until they are stopped by the 1st CPU
	* with smp_send_stop().
	*/
	if (!spin_trylock(&panic_lock))
	panic_smp_self_stop();

	console_verbose();
	bust_spinlocks(1);
	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);
	pr_emerg("Kernel panic - not syncing: %s\n", buf);
	#ifdef CONFIG_DEBUG_BUGVERBOSE
	/*
	* Avoid nested stack-dumping if a panic occurs during oops processing
	*/
	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
	dump_stack();
	#endif

	/*
	* If we have crashed and we have a crash kernel loaded let it handle
	* everything else.
	* If we want to run this after calling panic_notifiers, pass
	* the "crash_kexec_post_notifiers" option to the kernel.
	*/
	if (!crash_kexec_post_notifiers)
	crash_kexec(NULL);

	/*
	* Note smp_send_stop is the usual smp shutdown function, which
	* unfortunately means it may not be hardened to work in a panic
	* situation.
	*/
	smp_send_stop();

	/*
	* Run any panic handlers, including those that might need to
	* add information to the kmsg dump output.
	*/
	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);

	kmsg_dump(KMSG_DUMP_PANIC);

	/*
	* If you doubt kdump always works fine in any situation,
	* "crash_kexec_post_notifiers" offers you a chance to run
	* panic_notifiers and dumping kmsg before kdump.
	* Note: since some panic_notifiers can make crashed kernel
	* more unstable, it can increase risks of the kdump failure too.
	*/
	crash_kexec(NULL);

	bust_spinlocks(0);

	if (!panic_blink)
	panic_blink = no_blink;

	if (panic_timeout > 0) {
	/*
	* Delay timeout seconds before rebooting the machine.
	* We can't use the "normal" timers since we just panicked.
	*/
	pr_emerg("Rebooting in %d seconds..", panic_timeout);

	for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
	touch_nmi_watchdog();
	if (i >= i_next) {
	i += panic_blink(state ^= 1);
	i_next = i + 3600 / PANIC_BLINK_SPD;
	}
	mdelay(PANIC_TIMER_STEP);
	}
	}
	if (panic_timeout != 0) {
	/*
	* This will not be a clean reboot, with everything
	* shutting down. But if there is a chance of
	* rebooting the system it will be rebooted.
	*/
	emergency_restart();
	}
	#ifdef __sparc__
	{
	extern int stop_a_enabled;
	/* Make sure the user can actually press Stop-A (L1-A) */
	stop_a_enabled = 1;
	pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
	}
	#endif
	#if defined(CONFIG_S390)
	{
	unsigned long caller;

	caller = (unsigned long)__builtin_return_address(0);
	disabled_wait(caller);
	}
	#endif
	pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
	local_irq_enable();
	for (i = 0; ; i += PANIC_TIMER_STEP) {
	touch_softlockup_watchdog();
	if (i >= i_next) {
	i += panic_blink(state ^= 1);
	i_next = i + 3600 / PANIC_BLINK_SPD;
	}
	mdelay(PANIC_TIMER_STEP);
	}
	}

	EXPORT_SYMBOL(panic);


	struct tnt {
	u8 bit;
	char true;
	char false;
	};

	static const struct tnt tnts[] = {
	{ TAINT_PROPRIETARY_MODULE, 'P', 'G' },
	{ TAINT_FORCED_MODULE, 'F', ' ' },
	{ TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
	{ TAINT_FORCED_RMMOD, 'R', ' ' },
	{ TAINT_MACHINE_CHECK, 'M', ' ' },
	{ TAINT_BAD_PAGE, 'B', ' ' },
	{ TAINT_USER, 'U', ' ' },
	{ TAINT_DIE, 'D', ' ' },
	{ TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
	{ TAINT_WARN, 'W', ' ' },
	{ TAINT_CRAP, 'C', ' ' },
	{ TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
	{ TAINT_OOT_MODULE, 'O', ' ' },
	{ TAINT_UNSIGNED_MODULE, 'E', ' ' },
	{ TAINT_SOFTLOCKUP, 'L', ' ' },
	};

	/**
	* print_tainted - return a string to represent the kernel taint state.
	*
	* 'P' - Proprietary module has been loaded.
	* 'F' - Module has been forcibly loaded.
	* 'S' - SMP with CPUs not designed for SMP.
	* 'R' - User forced a module unload.
	* 'M' - System experienced a machine check exception.
	* 'B' - System has hit bad_page.
	* 'U' - Userspace-defined naughtiness.
	* 'D' - Kernel has oopsed before
	* 'A' - ACPI table overridden.
	* 'W' - Taint on warning.
	* 'C' - modules from drivers/staging are loaded.
	* 'I' - Working around severe firmware bug.
	* 'O' - Out-of-tree module has been loaded.
	* 'E' - Unsigned module has been loaded.
	*
	* The string is overwritten by the next call to print_tainted().
	*/
	const char *print_tainted(void)
	{
	static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];

	if (tainted_mask) {
	char *s;
	int i;

	s = buf + sprintf(buf, "Tainted: ");
	for (i = 0; i < ARRAY_SIZE(tnts); i++) {
	const struct tnt *t = &tnts[i];
	*s++ = test_bit(t->bit, &tainted_mask) ?
	t->true : t->false;
	}
	*s = 0;
	} else
	snprintf(buf, sizeof(buf), "Not tainted");

	return buf;
	}

	int test_taint(unsigned flag)
	{
	return test_bit(flag, &tainted_mask);
	}
	EXPORT_SYMBOL(test_taint);

	unsigned long get_taint(void)
	{
	return tainted_mask;
	}

	/**
	* add_taint: add a taint flag if not already set.
	* @flag: one of the TAINT_* constants.
	* @lockdep_ok: whether lock debugging is still OK.
	*
	* If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
	* some notewortht-but-not-corrupting cases, it can be set to true.
	*/
	void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
	{
	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
	pr_warn("Disabling lock debugging due to kernel taint\n");

	set_bit(flag, &tainted_mask);
	}
	EXPORT_SYMBOL(add_taint);

	static void spin_msec(int msecs)
	{
	int i;

	for (i = 0; i < msecs; i++) {
	touch_nmi_watchdog();
	mdelay(1);
	}
	}

	/*
	* It just happens that oops_enter() and oops_exit() are identically
	* implemented...
	*/
	static void do_oops_enter_exit(void)
	{
	unsigned long flags;
	static int spin_counter;

	if (!pause_on_oops)
	return;

	spin_lock_irqsave(&pause_on_oops_lock, flags);
	if (pause_on_oops_flag == 0) {
	/* This CPU may now print the oops message */
	pause_on_oops_flag = 1;
	} else {
	/* We need to stall this CPU */
	if (!spin_counter) {
	/* This CPU gets to do the counting */
	spin_counter = pause_on_oops;
	do {
	spin_unlock(&pause_on_oops_lock);
	spin_msec(MSEC_PER_SEC);
	spin_lock(&pause_on_oops_lock);
	} while (--spin_counter);
	pause_on_oops_flag = 0;
	} else {
	/* This CPU waits for a different one */
	while (spin_counter) {
	spin_unlock(&pause_on_oops_lock);
	spin_msec(1);
	spin_lock(&pause_on_oops_lock);
	}
	}
	}
	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
	}

	/*
	* Return true if the calling CPU is allowed to print oops-related info.
	* This is a bit racy..
	*/
	int oops_may_print(void)
	{
	return pause_on_oops_flag == 0;
	}

	/*
	* Called when the architecture enters its oops handler, before it prints
	* anything. If this is the first CPU to oops, and it's oopsing the first
	* time then let it proceed.
	*
	* This is all enabled by the pause_on_oops kernel boot option. We do all
	* this to ensure that oopses don't scroll off the screen. It has the
	* side-effect of preventing later-oopsing CPUs from mucking up the display,
	* too.
	*
	* It turns out that the CPU which is allowed to print ends up pausing for
	* the right duration, whereas all the other CPUs pause for twice as long:
	* once in oops_enter(), once in oops_exit().
	*/
	void oops_enter(void)
	{
	tracing_off();
	/* can't trust the integrity of the kernel anymore: */
	debug_locks_off();
	do_oops_enter_exit();
	}

	/*
	* 64-bit random ID for oopses:
	*/
	static u64 oops_id;

	static int init_oops_id(void)
	{
	if (!oops_id)
	get_random_bytes(&oops_id, sizeof(oops_id));
	else
	oops_id++;

	return 0;
	}
	late_initcall(init_oops_id);

	void print_oops_end_marker(void)
	{
	init_oops_id();
	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
	}

	/*
	* Called when the architecture exits its oops handler, after printing
	* everything.
	*/
	void oops_exit(void)
	{
	do_oops_enter_exit();
	print_oops_end_marker();
	kmsg_dump(KMSG_DUMP_OOPS);
	}

	#ifdef WANT_WARN_ON_SLOWPATH
	struct slowpath_args {
	const char *fmt;
	va_list args;
	};

	static void warn_slowpath_common(const char file, int line, void caller,
	unsigned taint, struct slowpath_args *args)
	{
	disable_trace_on_warning();

	pr_warn("------------[ cut here ]------------\n");
	pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
	raw_smp_processor_id(), current->pid, file, line, caller);

	if (args)
	vprintk(args->fmt, args->args);

	print_modules();
	dump_stack();
	print_oops_end_marker();
	/* Just a warning, don't kill lockdep. */
	add_taint(taint, LOCKDEP_STILL_OK);
	}

	void warn_slowpath_fmt(const char file, int line, const char fmt, ...)
	{
	struct slowpath_args args;

	args.fmt = fmt;
	va_start(args.args, fmt);
	warn_slowpath_common(file, line, __builtin_return_address(0),
	TAINT_WARN, &args);
	va_end(args.args);
	}
	EXPORT_SYMBOL(warn_slowpath_fmt);

	void warn_slowpath_fmt_taint(const char *file, int line,
	unsigned taint, const char *fmt, ...)
	{
	struct slowpath_args args;

	args.fmt = fmt;
	va_start(args.args, fmt);
	warn_slowpath_common(file, line, __builtin_return_address(0),
	taint, &args);
	va_end(args.args);
	}
	EXPORT_SYMBOL(warn_slowpath_fmt_taint);

	void warn_slowpath_null(const char *file, int line)
	{
	warn_slowpath_common(file, line, __builtin_return_address(0),
	TAINT_WARN, NULL);
	}
	EXPORT_SYMBOL(warn_slowpath_null);
	#endif

	#ifdef CONFIG_CC_STACKPROTECTOR

	/*
	* Called when gcc's -fstack-protector feature is used, and
	* gcc detects corruption of the on-stack canary value
	*/
	__visible void __stack_chk_fail(void)
	{
	panic("stack-protector: Kernel stack is corrupted in: %p\n",
	__builtin_return_address(0));
	}
	EXPORT_SYMBOL(__stack_chk_fail);

	#endif

	core_param(panic, panic_timeout, int, 0644);
	core_param(pause_on_oops, pause_on_oops, int, 0644);

	static int __init setup_crash_kexec_post_notifiers(char *s)
	{
	crash_kexec_post_notifiers = true;
	return 0;
	}
	early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);

	static int __init oops_setup(char *s)
	{
	if (!s)
	return -EINVAL;
	if (!strcmp(s, "panic"))
	panic_on_oops = 1;
	return 0;
	}
	early_param("oops", oops_setup);