kernel/panic.c - third_party/linux - Git at Google

 /*
  *  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>

 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);

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

 static void panic_blink_one_second(void)
 {
 	static long i = 0, end;

 	if (panic_blink) {
 		end = i + MSEC_PER_SEC;

 		while (i < end) {
 			i += panic_blink(i);
 			mdelay(1);
 			i++;
 		}
 	} else {
 		/*
 		 * When running under a hypervisor a small mdelay may get
 		 * rounded up to the hypervisor timeslice. For example, with
 		 * a 1ms in 10ms hypervisor timeslice we might inflate a
 		 * mdelay(1) loop by 10x.
 		 *
 		 * If we have nothing to blink, spin on 1 second calls to
 		 * mdelay to avoid this.
 		 */
 		mdelay(MSEC_PER_SEC);
 	}
 }

 /**
  *	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;

 	/*
 	 * 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

 	/*
 	 * 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_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; i++) {
 			touch_nmi_watchdog();
 			panic_blink_one_second();
 		}
 		/*
 		 * 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();
 	while (1) {
 		touch_softlockup_watchdog();
 		panic_blink_one_second();
 	}
 }

 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', ' ' },
 };

 /**
  *	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.
  *
  *	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);

 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();
 	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, 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_WARN);
 }

 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), &args);
 	va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt);

 void warn_slowpath_null(const char *file, int line)
 {
 	warn_slowpath_common(file, line, __builtin_return_address(0), 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);
	/*
	* 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>

	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);

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

	static void panic_blink_one_second(void)
	{
	static long i = 0, end;

	if (panic_blink) {
	end = i + MSEC_PER_SEC;

	while (i < end) {
	i += panic_blink(i);
	mdelay(1);
	i++;
	}
	} else {
	/*
	* When running under a hypervisor a small mdelay may get
	* rounded up to the hypervisor timeslice. For example, with
	* a 1ms in 10ms hypervisor timeslice we might inflate a
	* mdelay(1) loop by 10x.
	*
	* If we have nothing to blink, spin on 1 second calls to
	* mdelay to avoid this.
	*/
	mdelay(MSEC_PER_SEC);
	}
	}

	/**
	* 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;

	/*
	* 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

	/*
	* 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_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; i++) {
	touch_nmi_watchdog();
	panic_blink_one_second();
	}
	/*
	* 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();
	while (1) {
	touch_softlockup_watchdog();
	panic_blink_one_second();
	}
	}

	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', ' ' },
	};

	/**
	* 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.
	*
	* 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);

	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();
	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, 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_WARN);
	}

	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), &args);
	va_end(args.args);
	}
	EXPORT_SYMBOL(warn_slowpath_fmt);

	void warn_slowpath_null(const char *file, int line)
	{
	warn_slowpath_common(file, line, __builtin_return_address(0), 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);