[mirror_ubuntu-artful-kernel.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>
#include <linux/random.h>
#include <linux/kallsyms.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);
#ifdef CONFIG_DEBUG_BUGVERBOSE
	dump_stack();
#endif
	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' - System experienced a machine check exception.
 *  'B' - System has hit bad_page.
 *  'U' - Userspace-defined naughtiness.
 *  'A' - ACPI table overridden.
 *  'W' - Taint on warning.
 *
 *	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%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' : ' ',
			tainted & TAINT_OVERRIDDEN_ACPI_TABLE ? 'A' : ' ',
			tainted & TAINT_WARN ? 'W' : ' ');
	}
	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();
}

/*
 * 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));

	return 0;
}
late_initcall(init_oops_id);

static 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();
}

#ifdef WANT_WARN_ON_SLOWPATH
void warn_on_slowpath(const char *file, int line)
{
	char function[KSYM_SYMBOL_LEN];
	unsigned long caller = (unsigned long) __builtin_return_address(0);
	sprint_symbol(function, caller);

	printk(KERN_WARNING "------------[ cut here ]------------\n");
	printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
		line, function);
	print_modules();
	dump_stack();
	print_oops_end_marker();
	add_taint(TAINT_WARN);
}
EXPORT_SYMBOL(warn_on_slowpath);
#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
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>
2c3b20e9	22	#include <linux/random.h>
79b4cc5e	23	#include <linux/kallsyms.h>
1da177e4	24
1da177e4 LT	25	int panic_on_oops;
1da177e4 LT	26	int tainted;
dd287796 AM	27	static int pause_on_oops;
	28	static int pause_on_oops_flag;
	29	static DEFINE_SPINLOCK(pause_on_oops_lock);
1da177e4	30
dd287796	31	int panic_timeout;
1da177e4	32
e041c683	33	ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
1da177e4 LT	34
	35	EXPORT_SYMBOL(panic_notifier_list);
	36
	37	static int __init panic_setup(char *str)
	38	{
	39	panic_timeout = simple_strtoul(str, NULL, 0);
	40	return 1;
	41	}
	42	__setup("panic=", panic_setup);
	43
	44	static long no_blink(long time)
	45	{
	46	return 0;
	47	}
	48
	49	/* Returns how long it waited in ms */
	50	long (*panic_blink)(long time);
	51	EXPORT_SYMBOL(panic_blink);
	52
	53	/**
	54	* panic - halt the system
	55	* @fmt: The text string to print
	56	*
	57	* Display a message, then perform cleanups.
	58	*
	59	* This function never returns.
	60	*/
c277e63f	61
1da177e4 LT	62	NORET_TYPE void panic(const char * fmt, ...)
	63	{
	64	long i;
	65	static char buf[1024];
	66	va_list args;
347a8dc3	67	#if defined(CONFIG_S390)
c277e63f	68	unsigned long caller = (unsigned long) __builtin_return_address(0);
1da177e4 LT	69	#endif
1da177e4 LT	70
dc009d92 EB	71	/*
	72	* It's possible to come here directly from a panic-assertion and not
	73	* have preempt disabled. Some functions called from here want
	74	* preempt to be disabled. No point enabling it later though...
	75	*/
	76	preempt_disable();
	77
1da177e4 LT	78	bust_spinlocks(1);
	79	va_start(args, fmt);
	80	vsnprintf(buf, sizeof(buf), fmt, args);
	81	va_end(args);
	82	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
5cb27301 IM	83	#ifdef CONFIG_DEBUG_BUGVERBOSE
	84	dump_stack();
	85	#endif
1da177e4 LT	86	bust_spinlocks(0);
1da177e4 LT	87
dc009d92 EB	88	/*
	89	* If we have crashed and we have a crash kernel loaded let it handle
	90	* everything else.
	91	* Do we want to call this before we try to display a message?
	92	*/
6e274d14	93	crash_kexec(NULL);
dc009d92	94
1da177e4	95	#ifdef CONFIG_SMP
dc009d92 EB	96	/*
	97	* Note smp_send_stop is the usual smp shutdown function, which
	98	* unfortunately means it may not be hardened to work in a panic
	99	* situation.
	100	*/
1da177e4 LT	101	smp_send_stop();
	102	#endif
	103
e041c683	104	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
1da177e4 LT	105
	106	if (!panic_blink)
	107	panic_blink = no_blink;
	108
dc009d92	109	if (panic_timeout > 0) {
1da177e4 LT	110	/*
	111	* Delay timeout seconds before rebooting the machine.
	112	* We can't use the "normal" timers since we just panicked..
	113	*/
	114	printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout);
	115	for (i = 0; i < panic_timeout*1000; ) {
	116	touch_nmi_watchdog();
	117	i += panic_blink(i);
	118	mdelay(1);
	119	i++;
	120	}
2f048ea8 EB	121	/* This will not be a clean reboot, with everything
	122	* shutting down. But if there is a chance of
	123	* rebooting the system it will be rebooted.
1da177e4	124	*/
2f048ea8	125	emergency_restart();
1da177e4 LT	126	}
	127	#ifdef __sparc__
	128	{
	129	extern int stop_a_enabled;
a271c241	130	/* Make sure the user can actually press Stop-A (L1-A) */
1da177e4	131	stop_a_enabled = 1;
a271c241	132	printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
1da177e4 LT	133	}
1da177e4 LT	134	#endif
347a8dc3	135	#if defined(CONFIG_S390)
c277e63f	136	disabled_wait(caller);
1da177e4 LT	137	#endif
	138	local_irq_enable();
	139	for (i = 0;;) {
c22db941	140	touch_softlockup_watchdog();
1da177e4 LT	141	i += panic_blink(i);
	142	mdelay(1);
	143	i++;
	144	}
	145	}
	146
	147	EXPORT_SYMBOL(panic);
	148
	149	/**
	150	* print_tainted - return a string to represent the kernel taint state.
	151	*
	152	* 'P' - Proprietary module has been loaded.
	153	* 'F' - Module has been forcibly loaded.
	154	* 'S' - SMP with CPUs not designed for SMP.
	155	* 'R' - User forced a module unload.
9aa5e993	156	* 'M' - System experienced a machine check exception.
1da177e4	157	* 'B' - System has hit bad_page.
34f5a398	158	* 'U' - Userspace-defined naughtiness.
95b570c9 NH	159	* 'A' - ACPI table overridden.
95b570c9 NH	160	* 'W' - Taint on warning.
1da177e4 LT	161	*
	162	* The string is overwritten by the next call to print_taint().
	163	*/
c277e63f	164
1da177e4 LT	165	const char *print_tainted(void)
	166	{
	167	static char buf[20];
	168	if (tainted) {
95b570c9	169	snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c%c%c%c",
1da177e4 LT	170	tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G',
	171	tainted & TAINT_FORCED_MODULE ? 'F' : ' ',
	172	tainted & TAINT_UNSAFE_SMP ? 'S' : ' ',
	173	tainted & TAINT_FORCED_RMMOD ? 'R' : ' ',
c277e63f	174	tainted & TAINT_MACHINE_CHECK ? 'M' : ' ',
34f5a398	175	tainted & TAINT_BAD_PAGE ? 'B' : ' ',
bcdcd8e7	176	tainted & TAINT_USER ? 'U' : ' ',
6ed31e92	177	tainted & TAINT_DIE ? 'D' : ' ',
95b570c9 NH	178	tainted & TAINT_OVERRIDDEN_ACPI_TABLE ? 'A' : ' ',
95b570c9 NH	179	tainted & TAINT_WARN ? 'W' : ' ');
1da177e4 LT	180	}
	181	else
	182	snprintf(buf, sizeof(buf), "Not tainted");
	183	return(buf);
	184	}
	185
	186	void add_taint(unsigned flag)
	187	{
068c4579	188	debug_locks = 0; /* can't trust the integrity of the kernel anymore */
1da177e4 LT	189	tainted \|= flag;
	190	}
	191	EXPORT_SYMBOL(add_taint);
dd287796 AM	192
	193	static int __init pause_on_oops_setup(char *str)
	194	{
	195	pause_on_oops = simple_strtoul(str, NULL, 0);
	196	return 1;
	197	}
	198	__setup("pause_on_oops=", pause_on_oops_setup);
	199
	200	static void spin_msec(int msecs)
	201	{
	202	int i;
	203
	204	for (i = 0; i < msecs; i++) {
	205	touch_nmi_watchdog();
	206	mdelay(1);
	207	}
	208	}
	209
	210	/*
	211	* It just happens that oops_enter() and oops_exit() are identically
	212	* implemented...
	213	*/
	214	static void do_oops_enter_exit(void)
	215	{
	216	unsigned long flags;
	217	static int spin_counter;
	218
	219	if (!pause_on_oops)
	220	return;
	221
	222	spin_lock_irqsave(&pause_on_oops_lock, flags);
	223	if (pause_on_oops_flag == 0) {
	224	/* This CPU may now print the oops message */
	225	pause_on_oops_flag = 1;
	226	} else {
	227	/* We need to stall this CPU */
	228	if (!spin_counter) {
	229	/* This CPU gets to do the counting */
	230	spin_counter = pause_on_oops;
	231	do {
	232	spin_unlock(&pause_on_oops_lock);
	233	spin_msec(MSEC_PER_SEC);
	234	spin_lock(&pause_on_oops_lock);
	235	} while (--spin_counter);
	236	pause_on_oops_flag = 0;
	237	} else {
	238	/* This CPU waits for a different one */
	239	while (spin_counter) {
	240	spin_unlock(&pause_on_oops_lock);
	241	spin_msec(1);
	242	spin_lock(&pause_on_oops_lock);
	243	}
	244	}
	245	}
	246	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
	247	}
	248
	249	/*
	250	* Return true if the calling CPU is allowed to print oops-related info. This
	251	* is a bit racy..
	252	*/
	253	int oops_may_print(void)
	254	{
	255	return pause_on_oops_flag == 0;
256	}
257
258	/*
259	* Called when the architecture enters its oops handler, before it prints
260	* anything. If this is the first CPU to oops, and it's oopsing the first time
261	* then let it proceed.
262	*
263	* This is all enabled by the pause_on_oops kernel boot option. We do all this
264	* to ensure that oopses don't scroll off the screen. It has the side-effect
265	* of preventing later-oopsing CPUs from mucking up the display, too.
266	*
267	* It turns out that the CPU which is allowed to print ends up pausing for the
268	* right duration, whereas all the other CPUs pause for twice as long: once in
269	* oops_enter(), once in oops_exit().
270	*/
271	void oops_enter(void)
272	{
2c16e9c8	273	debug_locks_off(); /* can't trust the integrity of the kernel anymore */
dd287796 AM	274	do_oops_enter_exit();
	275	}
	276
2c3b20e9 AV	277	/*
	278	* 64-bit random ID for oopses:
	279	*/
	280	static u64 oops_id;
	281
	282	static int init_oops_id(void)
	283	{
	284	if (!oops_id)
	285	get_random_bytes(&oops_id, sizeof(oops_id));
	286
	287	return 0;
	288	}
	289	late_initcall(init_oops_id);
	290
71c33911 AV	291	static void print_oops_end_marker(void)
	292	{
	293	init_oops_id();
	294	printk(KERN_WARNING "---[ end trace %016llx ]---\n",
	295	(unsigned long long)oops_id);
	296	}
	297
dd287796 AM	298	/*
	299	* Called when the architecture exits its oops handler, after printing
	300	* everything.
	301	*/
	302	void oops_exit(void)
	303	{
	304	do_oops_enter_exit();
71c33911	305	print_oops_end_marker();
dd287796	306	}
3162f751	307
79b4cc5e AV	308	#ifdef WANT_WARN_ON_SLOWPATH
	309	void warn_on_slowpath(const char *file, int line)
	310	{
	311	char function[KSYM_SYMBOL_LEN];
	312	unsigned long caller = (unsigned long) __builtin_return_address(0);
79b4cc5e	313	sprint_symbol(function, caller);
71c33911 AV	314
71c33911 AV	315	printk(KERN_WARNING "------------[ cut here ]------------\n");
79b4cc5e AV	316	printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
79b4cc5e AV	317	line, function);
71c33911	318	print_modules();
79b4cc5e	319	dump_stack();
71c33911	320	print_oops_end_marker();
95b570c9	321	add_taint(TAINT_WARN);
79b4cc5e AV	322	}
	323	EXPORT_SYMBOL(warn_on_slowpath);
	324	#endif
	325
3162f751 AV	326	#ifdef CONFIG_CC_STACKPROTECTOR
	327	/*
	328	* Called when gcc's -fstack-protector feature is used, and
	329	* gcc detects corruption of the on-stack canary value
	330	*/
	331	void __stack_chk_fail(void)
	332	{
517a92c4 IM	333	panic("stack-protector: Kernel stack is corrupted in: %p\n",
517a92c4 IM	334	__builtin_return_address(0));
3162f751 AV	335	}
	336	EXPORT_SYMBOL(__stack_chk_fail);
	337	#endif