[linux.git] / kernel / panic.c

/*
 *  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/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>
#include <linux/dmi.h>

#define PANIC_TIMER_STEP 100
#define PANIC_BLINK_SPD 18

int panic_on_oops;
static unsigned long tainted_mask;
static int pause_on_oops;
static int pause_on_oops_flag;
static DEFINE_SPINLOCK(pause_on_oops_lock);

int 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);

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

	/*
	 * 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...
	 */
	preempt_disable();

	console_verbose();
	bust_spinlocks(1);
	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
	va_end(args);
	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
#ifdef CONFIG_DEBUG_BUGVERBOSE
	dump_stack();
#endif

	/*
	 * If we have crashed and we have a crash kernel loaded let it handle
	 * everything else.
	 * Do we want to call this before we try to display a message?
	 */
	crash_kexec(NULL);

	kmsg_dump(KMSG_DUMP_PANIC);

	/*
	 * 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();

	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);

	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.
		 */
		printk(KERN_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);
		}
		/*
		 * 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;
		printk(KERN_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
	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_UNSAFE_SMP,		'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', ' ' },
};

/**
 *	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.
 *
 *	The string is overwritten by the next call to print_tainted().
 */
const char *print_tainted(void)
{
	static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];

	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;
}

void add_taint(unsigned flag)
{
	/*
	 * Can't trust the integrity of the kernel anymore.
	 * We don't call directly debug_locks_off() because the issue
	 * is not necessarily serious enough to set oops_in_progress to 1
	 * Also we want to keep up lockdep for staging development and
	 * post-warning case.
	 */
	if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
		printk(KERN_WARNING "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();
	printk(KERN_WARNING "---[ 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)
{
	const char *board;

	printk(KERN_WARNING "------------[ cut here ]------------\n");
	printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
	board = dmi_get_system_info(DMI_PRODUCT_NAME);
	if (board)
		printk(KERN_WARNING "Hardware name: %s\n", board);

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

	print_modules();
	dump_stack();
	print_oops_end_marker();
	add_taint(taint);
}

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
 */
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);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/kernel/panic.c
	3	*
	4	* Copyright (C) 1991, 1992 Linus Torvalds
	5	*/
	6
	7	/*
	8	* This function is used through-out the kernel (including mm and fs)
	9	* to indicate a major problem.
	10	*/
c95dbf27 IM	11	#include <linux/debug_locks.h>
c95dbf27 IM	12	#include <linux/interrupt.h>
456b565c	13	#include <linux/kmsg_dump.h>
c95dbf27 IM	14	#include <linux/kallsyms.h>
c95dbf27 IM	15	#include <linux/notifier.h>
1da177e4	16	#include <linux/module.h>
c95dbf27	17	#include <linux/random.h>
1da177e4	18	#include <linux/reboot.h>
c95dbf27 IM	19	#include <linux/delay.h>
	20	#include <linux/kexec.h>
	21	#include <linux/sched.h>
1da177e4	22	#include <linux/sysrq.h>
c95dbf27	23	#include <linux/init.h>
1da177e4	24	#include <linux/nmi.h>
bd89bb29	25	#include <linux/dmi.h>
1da177e4	26
c7ff0d9c TS	27	#define PANIC_TIMER_STEP 100
	28	#define PANIC_BLINK_SPD 18
	29
1da177e4	30	int panic_on_oops;
25ddbb18	31	static unsigned long tainted_mask;
dd287796 AM	32	static int pause_on_oops;
	33	static int pause_on_oops_flag;
	34	static DEFINE_SPINLOCK(pause_on_oops_lock);
1da177e4	35
dd287796	36	int panic_timeout;
1da177e4	37
e041c683	38	ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
1da177e4 LT	39
	40	EXPORT_SYMBOL(panic_notifier_list);
	41
c7ff0d9c	42	static long no_blink(int state)
8aeee85a	43	{
c7ff0d9c	44	return 0;
8aeee85a AB	45	}
8aeee85a AB	46
c7ff0d9c TS	47	/* Returns how long it waited in ms */
	48	long (*panic_blink)(int state);
	49	EXPORT_SYMBOL(panic_blink);
	50
1da177e4 LT	51	/**
	52	* panic - halt the system
	53	* @fmt: The text string to print
	54	*
	55	* Display a message, then perform cleanups.
	56	*
	57	* This function never returns.
	58	*/
1da177e4 LT	59	NORET_TYPE void panic(const char * fmt, ...)
1da177e4 LT	60	{
1da177e4 LT	61	static char buf[1024];
1da177e4 LT	62	va_list args;
c7ff0d9c TS	63	long i, i_next = 0;
c7ff0d9c TS	64	int state = 0;
1da177e4	65
dc009d92	66	/*
c95dbf27 IM	67	* It's possible to come here directly from a panic-assertion and
c95dbf27 IM	68	* not have preempt disabled. Some functions called from here want
dc009d92 EB	69	* preempt to be disabled. No point enabling it later though...
	70	*/
	71	preempt_disable();
	72
5b530fc1	73	console_verbose();
1da177e4 LT	74	bust_spinlocks(1);
	75	va_start(args, fmt);
	76	vsnprintf(buf, sizeof(buf), fmt, args);
	77	va_end(args);
	78	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
5cb27301 IM	79	#ifdef CONFIG_DEBUG_BUGVERBOSE
	80	dump_stack();
	81	#endif
1da177e4	82
dc009d92 EB	83	/*
	84	* If we have crashed and we have a crash kernel loaded let it handle
	85	* everything else.
	86	* Do we want to call this before we try to display a message?
	87	*/
6e274d14	88	crash_kexec(NULL);
dc009d92	89
0f4bd46e KM	90	kmsg_dump(KMSG_DUMP_PANIC);
0f4bd46e KM	91
dc009d92 EB	92	/*
	93	* Note smp_send_stop is the usual smp shutdown function, which
	94	* unfortunately means it may not be hardened to work in a panic
	95	* situation.
	96	*/
1da177e4	97	smp_send_stop();
1da177e4	98
e041c683	99	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
1da177e4	100
d014e889 AK	101	bust_spinlocks(0);
d014e889 AK	102
c7ff0d9c TS	103	if (!panic_blink)
	104	panic_blink = no_blink;
	105
dc009d92	106	if (panic_timeout > 0) {
1da177e4	107	/*
c95dbf27 IM	108	* Delay timeout seconds before rebooting the machine.
	109	* We can't use the "normal" timers since we just panicked.
	110	*/
	111	printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
	112
c7ff0d9c	113	for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
1da177e4	114	touch_nmi_watchdog();
c7ff0d9c TS	115	if (i >= i_next) {
	116	i += panic_blink(state ^= 1);
	117	i_next = i + 3600 / PANIC_BLINK_SPD;
	118	}
	119	mdelay(PANIC_TIMER_STEP);
1da177e4	120	}
c95dbf27 IM	121	/*
	122	* This will not be a clean reboot, with everything
	123	* shutting down. But if there is a chance of
	124	* rebooting the system it will be rebooted.
1da177e4	125	*/
2f048ea8	126	emergency_restart();
1da177e4 LT	127	}
	128	#ifdef __sparc__
	129	{
	130	extern int stop_a_enabled;
a271c241	131	/* Make sure the user can actually press Stop-A (L1-A) */
1da177e4	132	stop_a_enabled = 1;
a271c241	133	printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
1da177e4 LT	134	}
1da177e4 LT	135	#endif
347a8dc3	136	#if defined(CONFIG_S390)
c95dbf27 IM	137	{
	138	unsigned long caller;
	139
	140	caller = (unsigned long)__builtin_return_address(0);
	141	disabled_wait(caller);
	142	}
1da177e4 LT	143	#endif
1da177e4 LT	144	local_irq_enable();
c7ff0d9c	145	for (i = 0; ; i += PANIC_TIMER_STEP) {
c22db941	146	touch_softlockup_watchdog();
c7ff0d9c TS	147	if (i >= i_next) {
	148	i += panic_blink(state ^= 1);
	149	i_next = i + 3600 / PANIC_BLINK_SPD;
	150	}
	151	mdelay(PANIC_TIMER_STEP);
1da177e4 LT	152	}
	153	}
	154
	155	EXPORT_SYMBOL(panic);
	156
c277e63f	157
25ddbb18	158	struct tnt {
c95dbf27 IM	159	u8 bit;
	160	char true;
	161	char false;
25ddbb18 AK	162	};
	163
	164	static const struct tnt tnts[] = {
c95dbf27 IM	165	{ TAINT_PROPRIETARY_MODULE, 'P', 'G' },
	166	{ TAINT_FORCED_MODULE, 'F', ' ' },
	167	{ TAINT_UNSAFE_SMP, 'S', ' ' },
	168	{ TAINT_FORCED_RMMOD, 'R', ' ' },
	169	{ TAINT_MACHINE_CHECK, 'M', ' ' },
	170	{ TAINT_BAD_PAGE, 'B', ' ' },
	171	{ TAINT_USER, 'U', ' ' },
	172	{ TAINT_DIE, 'D', ' ' },
	173	{ TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
	174	{ TAINT_WARN, 'W', ' ' },
	175	{ TAINT_CRAP, 'C', ' ' },
92946bc7	176	{ TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
25ddbb18 AK	177	};
25ddbb18 AK	178
1da177e4 LT	179	/**
	180	* print_tainted - return a string to represent the kernel taint state.
	181	*
	182	* 'P' - Proprietary module has been loaded.
	183	* 'F' - Module has been forcibly loaded.
	184	* 'S' - SMP with CPUs not designed for SMP.
	185	* 'R' - User forced a module unload.
9aa5e993	186	* 'M' - System experienced a machine check exception.
1da177e4	187	* 'B' - System has hit bad_page.
34f5a398	188	* 'U' - Userspace-defined naughtiness.
a8005992	189	* 'D' - Kernel has oopsed before
95b570c9 NH	190	* 'A' - ACPI table overridden.
95b570c9 NH	191	* 'W' - Taint on warning.
061b1bd3	192	* 'C' - modules from drivers/staging are loaded.
92946bc7	193	* 'I' - Working around severe firmware bug.
1da177e4	194	*
fe002a41	195	* The string is overwritten by the next call to print_tainted().
1da177e4	196	*/
1da177e4 LT	197	const char *print_tainted(void)
1da177e4 LT	198	{
25ddbb18 AK	199	static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
	200
	201	if (tainted_mask) {
	202	char *s;
	203	int i;
	204
	205	s = buf + sprintf(buf, "Tainted: ");
	206	for (i = 0; i < ARRAY_SIZE(tnts); i++) {
	207	const struct tnt *t = &tnts[i];
	208	*s++ = test_bit(t->bit, &tainted_mask) ?
	209	t->true : t->false;
	210	}
	211	*s = 0;
	212	} else
1da177e4	213	snprintf(buf, sizeof(buf), "Not tainted");
c95dbf27 IM	214
c95dbf27 IM	215	return buf;
1da177e4 LT	216	}
1da177e4 LT	217
25ddbb18	218	int test_taint(unsigned flag)
1da177e4	219	{
25ddbb18 AK	220	return test_bit(flag, &tainted_mask);
	221	}
	222	EXPORT_SYMBOL(test_taint);
	223
	224	unsigned long get_taint(void)
	225	{
	226	return tainted_mask;
1da177e4	227	}
dd287796	228
1da177e4	229	void add_taint(unsigned flag)
dd287796	230	{
9eeba613 FW	231	/*
	232	* Can't trust the integrity of the kernel anymore.
	233	* We don't call directly debug_locks_off() because the issue
	234	* is not necessarily serious enough to set oops_in_progress to 1
574bbe78 FW	235	* Also we want to keep up lockdep for staging development and
574bbe78 FW	236	* post-warning case.
9eeba613	237	*/
574bbe78	238	if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
b48ccb09	239	printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
9eeba613	240
25ddbb18	241	set_bit(flag, &tainted_mask);
dd287796	242	}
1da177e4	243	EXPORT_SYMBOL(add_taint);
dd287796 AM	244
	245	static void spin_msec(int msecs)
	246	{
	247	int i;
	248
	249	for (i = 0; i < msecs; i++) {
	250	touch_nmi_watchdog();
	251	mdelay(1);
	252	}
	253	}
	254
	255	/*
	256	* It just happens that oops_enter() and oops_exit() are identically
	257	* implemented...
	258	*/
	259	static void do_oops_enter_exit(void)
	260	{
	261	unsigned long flags;
	262	static int spin_counter;
	263
	264	if (!pause_on_oops)
	265	return;
	266
	267	spin_lock_irqsave(&pause_on_oops_lock, flags);
	268	if (pause_on_oops_flag == 0) {
	269	/* This CPU may now print the oops message */
	270	pause_on_oops_flag = 1;
	271	} else {
	272	/* We need to stall this CPU */
	273	if (!spin_counter) {
	274	/* This CPU gets to do the counting */
	275	spin_counter = pause_on_oops;
	276	do {
	277	spin_unlock(&pause_on_oops_lock);
	278	spin_msec(MSEC_PER_SEC);
	279	spin_lock(&pause_on_oops_lock);
	280	} while (--spin_counter);
	281	pause_on_oops_flag = 0;
	282	} else {
	283	/* This CPU waits for a different one */
	284	while (spin_counter) {
	285	spin_unlock(&pause_on_oops_lock);
	286	spin_msec(1);
	287	spin_lock(&pause_on_oops_lock);
	288	}
	289	}
	290	}
	291	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
	292	}
	293
	294	/*
c95dbf27 IM	295	* Return true if the calling CPU is allowed to print oops-related info.
c95dbf27 IM	296	* This is a bit racy..
dd287796 AM	297	*/
	298	int oops_may_print(void)
	299	{
	300	return pause_on_oops_flag == 0;
	301	}
	302
	303	/*
	304	* Called when the architecture enters its oops handler, before it prints
c95dbf27 IM	305	* anything. If this is the first CPU to oops, and it's oopsing the first
c95dbf27 IM	306	* time then let it proceed.
dd287796	307	*
c95dbf27 IM	308	* This is all enabled by the pause_on_oops kernel boot option. We do all
	309	* this to ensure that oopses don't scroll off the screen. It has the
	310	* side-effect of preventing later-oopsing CPUs from mucking up the display,
	311	* too.
dd287796	312	*
c95dbf27 IM	313	* It turns out that the CPU which is allowed to print ends up pausing for
	314	* the right duration, whereas all the other CPUs pause for twice as long:
	315	* once in oops_enter(), once in oops_exit().
dd287796 AM	316	*/
	317	void oops_enter(void)
	318	{
bdff7870	319	tracing_off();
c95dbf27 IM	320	/* can't trust the integrity of the kernel anymore: */
c95dbf27 IM	321	debug_locks_off();
dd287796 AM	322	do_oops_enter_exit();
	323	}
	324
2c3b20e9 AV	325	/*
	326	* 64-bit random ID for oopses:
	327	*/
	328	static u64 oops_id;
	329
	330	static int init_oops_id(void)
	331	{
	332	if (!oops_id)
	333	get_random_bytes(&oops_id, sizeof(oops_id));
d6624f99 AV	334	else
d6624f99 AV	335	oops_id++;
2c3b20e9 AV	336
	337	return 0;
	338	}
	339	late_initcall(init_oops_id);
	340
863a6049	341	void print_oops_end_marker(void)
71c33911 AV	342	{
	343	init_oops_id();
	344	printk(KERN_WARNING "---[ end trace %016llx ]---\n",
	345	(unsigned long long)oops_id);
	346	}
	347
dd287796 AM	348	/*
	349	* Called when the architecture exits its oops handler, after printing
	350	* everything.
	351	*/
	352	void oops_exit(void)
	353	{
	354	do_oops_enter_exit();
71c33911	355	print_oops_end_marker();
456b565c	356	kmsg_dump(KMSG_DUMP_OOPS);
dd287796	357	}
3162f751	358
79b4cc5e	359	#ifdef WANT_WARN_ON_SLOWPATH
0f6f49a8 LT	360	struct slowpath_args {
0f6f49a8 LT	361	const char *fmt;
a8f18b90	362	va_list args;
0f6f49a8	363	};
bd89bb29	364
b2be0527 BH	365	static void warn_slowpath_common(const char file, int line, void caller,
b2be0527 BH	366	unsigned taint, struct slowpath_args *args)
0f6f49a8 LT	367	{
0f6f49a8 LT	368	const char *board;
a8f18b90 AV	369
a8f18b90 AV	370	printk(KERN_WARNING "------------[ cut here ]------------\n");
0f6f49a8	371	printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
bd89bb29 AV	372	board = dmi_get_system_info(DMI_PRODUCT_NAME);
	373	if (board)
	374	printk(KERN_WARNING "Hardware name: %s\n", board);
74853dba	375
0f6f49a8 LT	376	if (args)
0f6f49a8 LT	377	vprintk(args->fmt, args->args);
a8f18b90 AV	378
	379	print_modules();
	380	dump_stack();
	381	print_oops_end_marker();
b2be0527	382	add_taint(taint);
a8f18b90	383	}
0f6f49a8 LT	384
	385	void warn_slowpath_fmt(const char file, int line, const char fmt, ...)
	386	{
	387	struct slowpath_args args;
	388
	389	args.fmt = fmt;
	390	va_start(args.args, fmt);
b2be0527 BH	391	warn_slowpath_common(file, line, __builtin_return_address(0),
b2be0527 BH	392	TAINT_WARN, &args);
0f6f49a8 LT	393	va_end(args.args);
0f6f49a8 LT	394	}
57adc4d2 AK	395	EXPORT_SYMBOL(warn_slowpath_fmt);
57adc4d2 AK	396
b2be0527 BH	397	void warn_slowpath_fmt_taint(const char *file, int line,
	398	unsigned taint, const char *fmt, ...)
	399	{
	400	struct slowpath_args args;
	401
	402	args.fmt = fmt;
	403	va_start(args.args, fmt);
	404	warn_slowpath_common(file, line, __builtin_return_address(0),
	405	taint, &args);
	406	va_end(args.args);
	407	}
	408	EXPORT_SYMBOL(warn_slowpath_fmt_taint);
	409
57adc4d2 AK	410	void warn_slowpath_null(const char *file, int line)
57adc4d2 AK	411	{
b2be0527 BH	412	warn_slowpath_common(file, line, __builtin_return_address(0),
b2be0527 BH	413	TAINT_WARN, NULL);
57adc4d2 AK	414	}
57adc4d2 AK	415	EXPORT_SYMBOL(warn_slowpath_null);
79b4cc5e AV	416	#endif
79b4cc5e AV	417
3162f751	418	#ifdef CONFIG_CC_STACKPROTECTOR
54371a43	419
3162f751 AV	420	/*
	421	* Called when gcc's -fstack-protector feature is used, and
	422	* gcc detects corruption of the on-stack canary value
	423	*/
	424	void __stack_chk_fail(void)
	425	{
517a92c4 IM	426	panic("stack-protector: Kernel stack is corrupted in: %p\n",
517a92c4 IM	427	__builtin_return_address(0));
3162f751 AV	428	}
3162f751 AV	429	EXPORT_SYMBOL(__stack_chk_fail);
54371a43	430
3162f751	431	#endif
f44dd164 RR	432
	433	core_param(panic, panic_timeout, int, 0644);
	434	core_param(pause_on_oops, pause_on_oops, int, 0644);