[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/module.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/notifier.h>
#include <linux/init.h>
#include <linux/sysrq.h>
#include <linux/interrupt.h>
#include <linux/nmi.h>
#include <linux/kexec.h>
#include <linux/debug_locks.h>

int panic_on_oops;
int tainted;
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 int __init panic_setup(char *str)
{
	panic_timeout = simple_strtoul(str, NULL, 0);
	return 1;
}
__setup("panic=", panic_setup);

static long no_blink(long time)
{
	return 0;
}

/* Returns how long it waited in ms */
long (*panic_blink)(long time);
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, ...)
{
	long i;
	static char buf[1024];
	va_list args;
#if defined(CONFIG_S390)
        unsigned long caller = (unsigned long) __builtin_return_address(0);
#endif

	/*
	 * 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();

	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);
	bust_spinlocks(0);

	/*
	 * 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);

#ifdef CONFIG_SMP
	/*
	 * 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();
#endif

	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);

	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; ) {
			touch_nmi_watchdog();
			i += panic_blink(i);
			mdelay(1);
			i++;
		}
		/*	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)
        disabled_wait(caller);
#endif
	local_irq_enable();
	for (i = 0;;) {
		touch_softlockup_watchdog();
		i += panic_blink(i);
		mdelay(1);
		i++;
	}
}

EXPORT_SYMBOL(panic);

/**
 *	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' - Machine had a machine check experience.
 *  'B' - System has hit bad_page.
 *  'U' - Userspace-defined naughtiness.
 *
 *	The string is overwritten by the next call to print_taint().
 */
 
const char *print_tainted(void)
{
	static char buf[20];
	if (tainted) {
		snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c",
			tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
			tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
			tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
			tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
 			tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
			tainted & TAINT_BAD_PAGE ? 'B' : ' ',
			tainted & TAINT_USER ? 'U' : ' ',
			tainted & TAINT_DIE ? 'D' : ' ');
	}
	else
		snprintf(buf, sizeof(buf), "Not tainted");
	return(buf);
}

void add_taint(unsigned flag)
{
	debug_locks = 0; /* can't trust the integrity of the kernel anymore */
	tainted |= flag;
}
EXPORT_SYMBOL(add_taint);

static int __init pause_on_oops_setup(char *str)
{
	pause_on_oops = simple_strtoul(str, NULL, 0);
	return 1;
}
__setup("pause_on_oops=", pause_on_oops_setup);

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)
{
	debug_locks_off(); /* can't trust the integrity of the kernel anymore */
	do_oops_enter_exit();
}

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

#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");
}
EXPORT_SYMBOL(__stack_chk_fail);
#endif
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	*/
1da177e4 LT	11	#include <linux/module.h>
	12	#include <linux/sched.h>
	13	#include <linux/delay.h>
	14	#include <linux/reboot.h>
	15	#include <linux/notifier.h>
	16	#include <linux/init.h>
	17	#include <linux/sysrq.h>
	18	#include <linux/interrupt.h>
	19	#include <linux/nmi.h>
dc009d92	20	#include <linux/kexec.h>
657b3010	21	#include <linux/debug_locks.h>
1da177e4	22
1da177e4 LT	23	int panic_on_oops;
1da177e4 LT	24	int tainted;
dd287796 AM	25	static int pause_on_oops;
	26	static int pause_on_oops_flag;
	27	static DEFINE_SPINLOCK(pause_on_oops_lock);
1da177e4	28
dd287796	29	int panic_timeout;
1da177e4	30
e041c683	31	ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
1da177e4 LT	32
	33	EXPORT_SYMBOL(panic_notifier_list);
	34
	35	static int __init panic_setup(char *str)
	36	{
	37	panic_timeout = simple_strtoul(str, NULL, 0);
	38	return 1;
	39	}
	40	__setup("panic=", panic_setup);
	41
	42	static long no_blink(long time)
	43	{
	44	return 0;
	45	}
	46
	47	/* Returns how long it waited in ms */
	48	long (*panic_blink)(long time);
	49	EXPORT_SYMBOL(panic_blink);
	50
	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	*/
	59
	60	NORET_TYPE void panic(const char * fmt, ...)
	61	{
	62	long i;
	63	static char buf[1024];
	64	va_list args;
347a8dc3	65	#if defined(CONFIG_S390)
1da177e4 LT	66	unsigned long caller = (unsigned long) __builtin_return_address(0);
	67	#endif
	68
dc009d92 EB	69	/*
	70	* It's possible to come here directly from a panic-assertion and not
	71	* have preempt disabled. Some functions called from here want
	72	* preempt to be disabled. No point enabling it later though...
	73	*/
	74	preempt_disable();
	75
1da177e4 LT	76	bust_spinlocks(1);
	77	va_start(args, fmt);
	78	vsnprintf(buf, sizeof(buf), fmt, args);
	79	va_end(args);
	80	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
	81	bust_spinlocks(0);
	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
1da177e4	90	#ifdef CONFIG_SMP
dc009d92 EB	91	/*
	92	* Note smp_send_stop is the usual smp shutdown function, which
	93	* unfortunately means it may not be hardened to work in a panic
	94	* situation.
	95	*/
1da177e4 LT	96	smp_send_stop();
	97	#endif
	98
e041c683	99	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
1da177e4 LT	100
	101	if (!panic_blink)
	102	panic_blink = no_blink;
	103
dc009d92	104	if (panic_timeout > 0) {
1da177e4 LT	105	/*
	106	* Delay timeout seconds before rebooting the machine.
	107	* We can't use the "normal" timers since we just panicked..
	108	*/
	109	printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
	110	for (i = 0; i < panic_timeout*1000; ) {
	111	touch_nmi_watchdog();
	112	i += panic_blink(i);
	113	mdelay(1);
	114	i++;
	115	}
2f048ea8 EB	116	/* This will not be a clean reboot, with everything
	117	* shutting down. But if there is a chance of
	118	* rebooting the system it will be rebooted.
1da177e4	119	*/
2f048ea8	120	emergency_restart();
1da177e4 LT	121	}
	122	#ifdef __sparc__
	123	{
	124	extern int stop_a_enabled;
a271c241	125	/* Make sure the user can actually press Stop-A (L1-A) */
1da177e4	126	stop_a_enabled = 1;
a271c241	127	printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
1da177e4 LT	128	}
1da177e4 LT	129	#endif
347a8dc3	130	#if defined(CONFIG_S390)
1da177e4 LT	131	disabled_wait(caller);
	132	#endif
	133	local_irq_enable();
	134	for (i = 0;;) {
c22db941	135	touch_softlockup_watchdog();
1da177e4 LT	136	i += panic_blink(i);
	137	mdelay(1);
	138	i++;
	139	}
	140	}
	141
	142	EXPORT_SYMBOL(panic);
	143
	144	/**
	145	* print_tainted - return a string to represent the kernel taint state.
	146	*
	147	* 'P' - Proprietary module has been loaded.
	148	* 'F' - Module has been forcibly loaded.
	149	* 'S' - SMP with CPUs not designed for SMP.
	150	* 'R' - User forced a module unload.
	151	* 'M' - Machine had a machine check experience.
	152	* 'B' - System has hit bad_page.
34f5a398	153	* 'U' - Userspace-defined naughtiness.
1da177e4 LT	154	*
	155	* The string is overwritten by the next call to print_taint().
	156	*/
	157
	158	const char *print_tainted(void)
	159	{
	160	static char buf[20];
	161	if (tainted) {
bcdcd8e7	162	snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c",
1da177e4 LT	163	tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
	164	tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
	165	tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
	166	tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
	167	tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
34f5a398	168	tainted & TAINT_BAD_PAGE ? 'B' : ' ',
bcdcd8e7 PE	169	tainted & TAINT_USER ? 'U' : ' ',
bcdcd8e7 PE	170	tainted & TAINT_DIE ? 'D' : ' ');
1da177e4 LT	171	}
	172	else
	173	snprintf(buf, sizeof(buf), "Not tainted");
	174	return(buf);
	175	}
	176
	177	void add_taint(unsigned flag)
	178	{
068c4579	179	debug_locks = 0; /* can't trust the integrity of the kernel anymore */
1da177e4 LT	180	tainted \|= flag;
	181	}
	182	EXPORT_SYMBOL(add_taint);
dd287796 AM	183
	184	static int __init pause_on_oops_setup(char *str)
	185	{
	186	pause_on_oops = simple_strtoul(str, NULL, 0);
	187	return 1;
	188	}
	189	__setup("pause_on_oops=", pause_on_oops_setup);
	190
	191	static void spin_msec(int msecs)
	192	{
	193	int i;
	194
	195	for (i = 0; i < msecs; i++) {
	196	touch_nmi_watchdog();
	197	mdelay(1);
	198	}
	199	}
	200
	201	/*
	202	* It just happens that oops_enter() and oops_exit() are identically
	203	* implemented...
	204	*/
	205	static void do_oops_enter_exit(void)
	206	{
	207	unsigned long flags;
	208	static int spin_counter;
	209
	210	if (!pause_on_oops)
	211	return;
	212
	213	spin_lock_irqsave(&pause_on_oops_lock, flags);
	214	if (pause_on_oops_flag == 0) {
	215	/* This CPU may now print the oops message */
	216	pause_on_oops_flag = 1;
	217	} else {
	218	/* We need to stall this CPU */
	219	if (!spin_counter) {
	220	/* This CPU gets to do the counting */
	221	spin_counter = pause_on_oops;
	222	do {
	223	spin_unlock(&pause_on_oops_lock);
	224	spin_msec(MSEC_PER_SEC);
	225	spin_lock(&pause_on_oops_lock);
	226	} while (--spin_counter);
	227	pause_on_oops_flag = 0;
	228	} else {
	229	/* This CPU waits for a different one */
	230	while (spin_counter) {
	231	spin_unlock(&pause_on_oops_lock);
	232	spin_msec(1);
	233	spin_lock(&pause_on_oops_lock);
	234	}
	235	}
	236	}
	237	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
	238	}
	239
	240	/*
	241	* Return true if the calling CPU is allowed to print oops-related info. This
	242	* is a bit racy..
	243	*/
	244	int oops_may_print(void)
	245	{
	246	return pause_on_oops_flag == 0;
247	}
248
249	/*
250	* Called when the architecture enters its oops handler, before it prints
251	* anything. If this is the first CPU to oops, and it's oopsing the first time
252	* then let it proceed.
253	*
254	* This is all enabled by the pause_on_oops kernel boot option. We do all this
255	* to ensure that oopses don't scroll off the screen. It has the side-effect
256	* of preventing later-oopsing CPUs from mucking up the display, too.
257	*
258	* It turns out that the CPU which is allowed to print ends up pausing for the
259	* right duration, whereas all the other CPUs pause for twice as long: once in
260	* oops_enter(), once in oops_exit().
261	*/
262	void oops_enter(void)
263	{
2c16e9c8	264	debug_locks_off(); /* can't trust the integrity of the kernel anymore */
dd287796 AM	265	do_oops_enter_exit();
	266	}
	267
	268	/*
	269	* Called when the architecture exits its oops handler, after printing
	270	* everything.
	271	*/
	272	void oops_exit(void)
	273	{
	274	do_oops_enter_exit();
	275	}
3162f751 AV	276
	277	#ifdef CONFIG_CC_STACKPROTECTOR
	278	/*
	279	* Called when gcc's -fstack-protector feature is used, and
	280	* gcc detects corruption of the on-stack canary value
	281	*/
	282	void __stack_chk_fail(void)
	283	{
	284	panic("stack-protector: Kernel stack is corrupted");
	285	}
	286	EXPORT_SYMBOL(__stack_chk_fail);
	287	#endif