[linux-2.6-block.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/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);
bool crash_kexec_post_notifiers;
int panic_on_warn __read_mostly;

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.
	 */
	if (crash_kexec_post_notifiers)
		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', ' ' },
	{ TAINT_LIVEPATCH,		'K', ' ' },
};

/**
 *	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.
 *  'L' - A soft lockup has previously occurred.
 *  'K' - Kernel has been live patched.
 *
 *	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);

	if (panic_on_warn) {
		/*
		 * This thread may hit another WARN() in the panic path.
		 * Resetting this prevents additional WARN() from panicking the
		 * system on this thread.  Other threads are blocked by the
		 * panic_mutex in panic().
		 */
		panic_on_warn = 0;
		panic("panic_on_warn set ...\n");
	}

	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);
core_param(panic_on_warn, panic_on_warn, 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);
Commit	Line	Data
	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	*/
	11	#include <linux/debug_locks.h>
	12	#include <linux/interrupt.h>
	13	#include <linux/kmsg_dump.h>
	14	#include <linux/kallsyms.h>
	15	#include <linux/notifier.h>
	16	#include <linux/module.h>
	17	#include <linux/random.h>
	18	#include <linux/ftrace.h>
	19	#include <linux/reboot.h>
	20	#include <linux/delay.h>
	21	#include <linux/kexec.h>
	22	#include <linux/sched.h>
	23	#include <linux/sysrq.h>
	24	#include <linux/init.h>
	25	#include <linux/nmi.h>
	26
	27	#define PANIC_TIMER_STEP 100
	28	#define PANIC_BLINK_SPD 18
	29
	30	int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
	31	static unsigned long tainted_mask;
	32	static int pause_on_oops;
	33	static int pause_on_oops_flag;
	34	static DEFINE_SPINLOCK(pause_on_oops_lock);
	35	bool crash_kexec_post_notifiers;
	36	int panic_on_warn __read_mostly;
	37
	38	int panic_timeout = CONFIG_PANIC_TIMEOUT;
	39	EXPORT_SYMBOL_GPL(panic_timeout);
	40
	41	ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
	42
	43	EXPORT_SYMBOL(panic_notifier_list);
	44
	45	static long no_blink(int state)
	46	{
	47	return 0;
	48	}
	49
	50	/* Returns how long it waited in ms */
	51	long (*panic_blink)(int state);
	52	EXPORT_SYMBOL(panic_blink);
	53
	54	/*
	55	* Stop ourself in panic -- architecture code may override this
	56	*/
	57	void __weak panic_smp_self_stop(void)
	58	{
	59	while (1)
	60	cpu_relax();
	61	}
	62
	63	/**
	64	* panic - halt the system
	65	* @fmt: The text string to print
	66	*
	67	* Display a message, then perform cleanups.
	68	*
	69	* This function never returns.
	70	*/
	71	void panic(const char *fmt, ...)
	72	{
	73	static DEFINE_SPINLOCK(panic_lock);
	74	static char buf[1024];
	75	va_list args;
	76	long i, i_next = 0;
	77	int state = 0;
	78
	79	/*
	80	* Disable local interrupts. This will prevent panic_smp_self_stop
	81	* from deadlocking the first cpu that invokes the panic, since
	82	* there is nothing to prevent an interrupt handler (that runs
	83	* after the panic_lock is acquired) from invoking panic again.
	84	*/
	85	local_irq_disable();
	86
	87	/*
	88	* It's possible to come here directly from a panic-assertion and
	89	* not have preempt disabled. Some functions called from here want
	90	* preempt to be disabled. No point enabling it later though...
	91	*
	92	* Only one CPU is allowed to execute the panic code from here. For
	93	* multiple parallel invocations of panic, all other CPUs either
	94	* stop themself or will wait until they are stopped by the 1st CPU
	95	* with smp_send_stop().
	96	*/
	97	if (!spin_trylock(&panic_lock))
	98	panic_smp_self_stop();
	99
	100	console_verbose();
	101	bust_spinlocks(1);
	102	va_start(args, fmt);
	103	vsnprintf(buf, sizeof(buf), fmt, args);
	104	va_end(args);
	105	pr_emerg("Kernel panic - not syncing: %s\n", buf);
	106	#ifdef CONFIG_DEBUG_BUGVERBOSE
	107	/*
	108	* Avoid nested stack-dumping if a panic occurs during oops processing
	109	*/
	110	if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
	111	dump_stack();
	112	#endif
	113
	114	/*
	115	* If we have crashed and we have a crash kernel loaded let it handle
	116	* everything else.
	117	* If we want to run this after calling panic_notifiers, pass
	118	* the "crash_kexec_post_notifiers" option to the kernel.
	119	*/
	120	if (!crash_kexec_post_notifiers)
	121	crash_kexec(NULL);
	122
	123	/*
	124	* Note smp_send_stop is the usual smp shutdown function, which
	125	* unfortunately means it may not be hardened to work in a panic
	126	* situation.
	127	*/
	128	smp_send_stop();
	129
	130	/*
	131	* Run any panic handlers, including those that might need to
	132	* add information to the kmsg dump output.
	133	*/
	134	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
	135
	136	kmsg_dump(KMSG_DUMP_PANIC);
	137
	138	/*
	139	* If you doubt kdump always works fine in any situation,
	140	* "crash_kexec_post_notifiers" offers you a chance to run
	141	* panic_notifiers and dumping kmsg before kdump.
	142	* Note: since some panic_notifiers can make crashed kernel
	143	* more unstable, it can increase risks of the kdump failure too.
	144	*/
	145	if (crash_kexec_post_notifiers)
	146	crash_kexec(NULL);
	147
	148	bust_spinlocks(0);
	149
	150	if (!panic_blink)
	151	panic_blink = no_blink;
	152
	153	if (panic_timeout > 0) {
	154	/*
	155	* Delay timeout seconds before rebooting the machine.
	156	* We can't use the "normal" timers since we just panicked.
	157	*/
	158	pr_emerg("Rebooting in %d seconds..", panic_timeout);
	159
	160	for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
	161	touch_nmi_watchdog();
	162	if (i >= i_next) {
	163	i += panic_blink(state ^= 1);
	164	i_next = i + 3600 / PANIC_BLINK_SPD;
	165	}
	166	mdelay(PANIC_TIMER_STEP);
	167	}
	168	}
	169	if (panic_timeout != 0) {
	170	/*
	171	* This will not be a clean reboot, with everything
	172	* shutting down. But if there is a chance of
	173	* rebooting the system it will be rebooted.
	174	*/
	175	emergency_restart();
	176	}
	177	#ifdef __sparc__
	178	{
	179	extern int stop_a_enabled;
	180	/* Make sure the user can actually press Stop-A (L1-A) */
	181	stop_a_enabled = 1;
	182	pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
	183	}
	184	#endif
	185	#if defined(CONFIG_S390)
	186	{
	187	unsigned long caller;
	188
	189	caller = (unsigned long)__builtin_return_address(0);
	190	disabled_wait(caller);
	191	}
	192	#endif
	193	pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
	194	local_irq_enable();
	195	for (i = 0; ; i += PANIC_TIMER_STEP) {
	196	touch_softlockup_watchdog();
	197	if (i >= i_next) {
	198	i += panic_blink(state ^= 1);
	199	i_next = i + 3600 / PANIC_BLINK_SPD;
	200	}
	201	mdelay(PANIC_TIMER_STEP);
	202	}
	203	}
	204
	205	EXPORT_SYMBOL(panic);
	206
	207
	208	struct tnt {
	209	u8 bit;
	210	char true;
	211	char false;
	212	};
	213
	214	static const struct tnt tnts[] = {
	215	{ TAINT_PROPRIETARY_MODULE, 'P', 'G' },
	216	{ TAINT_FORCED_MODULE, 'F', ' ' },
	217	{ TAINT_CPU_OUT_OF_SPEC, 'S', ' ' },
	218	{ TAINT_FORCED_RMMOD, 'R', ' ' },
	219	{ TAINT_MACHINE_CHECK, 'M', ' ' },
	220	{ TAINT_BAD_PAGE, 'B', ' ' },
	221	{ TAINT_USER, 'U', ' ' },
	222	{ TAINT_DIE, 'D', ' ' },
	223	{ TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' },
	224	{ TAINT_WARN, 'W', ' ' },
	225	{ TAINT_CRAP, 'C', ' ' },
	226	{ TAINT_FIRMWARE_WORKAROUND, 'I', ' ' },
	227	{ TAINT_OOT_MODULE, 'O', ' ' },
	228	{ TAINT_UNSIGNED_MODULE, 'E', ' ' },
	229	{ TAINT_SOFTLOCKUP, 'L', ' ' },
	230	{ TAINT_LIVEPATCH, 'K', ' ' },
	231	};
	232
	233	/**
	234	* print_tainted - return a string to represent the kernel taint state.
	235	*
	236	* 'P' - Proprietary module has been loaded.
	237	* 'F' - Module has been forcibly loaded.
	238	* 'S' - SMP with CPUs not designed for SMP.
	239	* 'R' - User forced a module unload.
	240	* 'M' - System experienced a machine check exception.
	241	* 'B' - System has hit bad_page.
	242	* 'U' - Userspace-defined naughtiness.
	243	* 'D' - Kernel has oopsed before
	244	* 'A' - ACPI table overridden.
	245	* 'W' - Taint on warning.
	246	* 'C' - modules from drivers/staging are loaded.
	247	* 'I' - Working around severe firmware bug.
	248	* 'O' - Out-of-tree module has been loaded.
	249	* 'E' - Unsigned module has been loaded.
	250	* 'L' - A soft lockup has previously occurred.
	251	* 'K' - Kernel has been live patched.
	252	*
	253	* The string is overwritten by the next call to print_tainted().
	254	*/
	255	const char *print_tainted(void)
	256	{
	257	static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
	258
	259	if (tainted_mask) {
	260	char *s;
	261	int i;
	262
	263	s = buf + sprintf(buf, "Tainted: ");
	264	for (i = 0; i < ARRAY_SIZE(tnts); i++) {
	265	const struct tnt *t = &tnts[i];
	266	*s++ = test_bit(t->bit, &tainted_mask) ?
	267	t->true : t->false;
	268	}
	269	*s = 0;
	270	} else
	271	snprintf(buf, sizeof(buf), "Not tainted");
	272
	273	return buf;
	274	}
	275
	276	int test_taint(unsigned flag)
	277	{
	278	return test_bit(flag, &tainted_mask);
	279	}
	280	EXPORT_SYMBOL(test_taint);
	281
	282	unsigned long get_taint(void)
	283	{
	284	return tainted_mask;
	285	}
	286
	287	/**
	288	* add_taint: add a taint flag if not already set.
	289	* @flag: one of the TAINT_* constants.
	290	* @lockdep_ok: whether lock debugging is still OK.
	291	*
	292	* If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
	293	* some notewortht-but-not-corrupting cases, it can be set to true.
	294	*/
	295	void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
	296	{
	297	if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
	298	pr_warn("Disabling lock debugging due to kernel taint\n");
	299
	300	set_bit(flag, &tainted_mask);
	301	}
	302	EXPORT_SYMBOL(add_taint);
	303
	304	static void spin_msec(int msecs)
	305	{
	306	int i;
	307
	308	for (i = 0; i < msecs; i++) {
	309	touch_nmi_watchdog();
	310	mdelay(1);
	311	}
	312	}
	313
	314	/*
	315	* It just happens that oops_enter() and oops_exit() are identically
	316	* implemented...
	317	*/
	318	static void do_oops_enter_exit(void)
	319	{
	320	unsigned long flags;
	321	static int spin_counter;
	322
	323	if (!pause_on_oops)
	324	return;
	325
	326	spin_lock_irqsave(&pause_on_oops_lock, flags);
	327	if (pause_on_oops_flag == 0) {
	328	/* This CPU may now print the oops message */
	329	pause_on_oops_flag = 1;
	330	} else {
	331	/* We need to stall this CPU */
	332	if (!spin_counter) {
	333	/* This CPU gets to do the counting */
	334	spin_counter = pause_on_oops;
	335	do {
	336	spin_unlock(&pause_on_oops_lock);
	337	spin_msec(MSEC_PER_SEC);
	338	spin_lock(&pause_on_oops_lock);
	339	} while (--spin_counter);
	340	pause_on_oops_flag = 0;
	341	} else {
	342	/* This CPU waits for a different one */
	343	while (spin_counter) {
	344	spin_unlock(&pause_on_oops_lock);
	345	spin_msec(1);
	346	spin_lock(&pause_on_oops_lock);
	347	}
	348	}
	349	}
	350	spin_unlock_irqrestore(&pause_on_oops_lock, flags);
	351	}
	352
	353	/*
	354	* Return true if the calling CPU is allowed to print oops-related info.
	355	* This is a bit racy..
	356	*/
	357	int oops_may_print(void)
	358	{
	359	return pause_on_oops_flag == 0;
	360	}
	361
	362	/*
	363	* Called when the architecture enters its oops handler, before it prints
	364	* anything. If this is the first CPU to oops, and it's oopsing the first
	365	* time then let it proceed.
	366	*
	367	* This is all enabled by the pause_on_oops kernel boot option. We do all
	368	* this to ensure that oopses don't scroll off the screen. It has the
	369	* side-effect of preventing later-oopsing CPUs from mucking up the display,
	370	* too.
	371	*
	372	* It turns out that the CPU which is allowed to print ends up pausing for
	373	* the right duration, whereas all the other CPUs pause for twice as long:
	374	* once in oops_enter(), once in oops_exit().
	375	*/
	376	void oops_enter(void)
	377	{
	378	tracing_off();
	379	/* can't trust the integrity of the kernel anymore: */
	380	debug_locks_off();
	381	do_oops_enter_exit();
	382	}
	383
	384	/*
	385	* 64-bit random ID for oopses:
	386	*/
	387	static u64 oops_id;
	388
	389	static int init_oops_id(void)
	390	{
	391	if (!oops_id)
	392	get_random_bytes(&oops_id, sizeof(oops_id));
	393	else
	394	oops_id++;
	395
	396	return 0;
	397	}
	398	late_initcall(init_oops_id);
	399
	400	void print_oops_end_marker(void)
	401	{
	402	init_oops_id();
	403	pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
	404	}
	405
	406	/*
	407	* Called when the architecture exits its oops handler, after printing
	408	* everything.
	409	*/
	410	void oops_exit(void)
	411	{
	412	do_oops_enter_exit();
	413	print_oops_end_marker();
	414	kmsg_dump(KMSG_DUMP_OOPS);
	415	}
	416
	417	#ifdef WANT_WARN_ON_SLOWPATH
	418	struct slowpath_args {
	419	const char *fmt;
	420	va_list args;
	421	};
	422
	423	static void warn_slowpath_common(const char file, int line, void caller,
	424	unsigned taint, struct slowpath_args *args)
	425	{
	426	disable_trace_on_warning();
	427
	428	pr_warn("------------[ cut here ]------------\n");
	429	pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
	430	raw_smp_processor_id(), current->pid, file, line, caller);
	431
	432	if (args)
	433	vprintk(args->fmt, args->args);
	434
	435	if (panic_on_warn) {
	436	/*
	437	* This thread may hit another WARN() in the panic path.
	438	* Resetting this prevents additional WARN() from panicking the
	439	* system on this thread. Other threads are blocked by the
	440	* panic_mutex in panic().
	441	*/
	442	panic_on_warn = 0;
	443	panic("panic_on_warn set ...\n");
	444	}
	445
	446	print_modules();
	447	dump_stack();
	448	print_oops_end_marker();
	449	/* Just a warning, don't kill lockdep. */
	450	add_taint(taint, LOCKDEP_STILL_OK);
	451	}
	452
	453	void warn_slowpath_fmt(const char file, int line, const char fmt, ...)
	454	{
	455	struct slowpath_args args;
	456
	457	args.fmt = fmt;
	458	va_start(args.args, fmt);
	459	warn_slowpath_common(file, line, __builtin_return_address(0),
	460	TAINT_WARN, &args);
	461	va_end(args.args);
	462	}
	463	EXPORT_SYMBOL(warn_slowpath_fmt);
	464
	465	void warn_slowpath_fmt_taint(const char *file, int line,
	466	unsigned taint, const char *fmt, ...)
	467	{
	468	struct slowpath_args args;
	469
	470	args.fmt = fmt;
	471	va_start(args.args, fmt);
	472	warn_slowpath_common(file, line, __builtin_return_address(0),
	473	taint, &args);
	474	va_end(args.args);
	475	}
	476	EXPORT_SYMBOL(warn_slowpath_fmt_taint);
	477
	478	void warn_slowpath_null(const char *file, int line)
	479	{
	480	warn_slowpath_common(file, line, __builtin_return_address(0),
	481	TAINT_WARN, NULL);
	482	}
	483	EXPORT_SYMBOL(warn_slowpath_null);
	484	#endif
	485
	486	#ifdef CONFIG_CC_STACKPROTECTOR
	487
	488	/*
	489	* Called when gcc's -fstack-protector feature is used, and
	490	* gcc detects corruption of the on-stack canary value
	491	*/
	492	__visible void __stack_chk_fail(void)
	493	{
	494	panic("stack-protector: Kernel stack is corrupted in: %p\n",
	495	__builtin_return_address(0));
	496	}
	497	EXPORT_SYMBOL(__stack_chk_fail);
	498
	499	#endif
	500
	501	core_param(panic, panic_timeout, int, 0644);
	502	core_param(pause_on_oops, pause_on_oops, int, 0644);
	503	core_param(panic_on_warn, panic_on_warn, int, 0644);
	504
	505	static int __init setup_crash_kexec_post_notifiers(char *s)
	506	{
	507	crash_kexec_post_notifiers = true;
	508	return 0;
	509	}
	510	early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
	511
	512	static int __init oops_setup(char *s)
	513	{
	514	if (!s)
	515	return -EINVAL;
	516	if (!strcmp(s, "panic"))
	517	panic_on_oops = 1;
	518	return 0;
	519	}
	520	early_param("oops", oops_setup);