[linux.git] / kernel / reboot.c

/*
 *  linux/kernel/reboot.c
 *
 *  Copyright (C) 2013  Linus Torvalds
 */

#define pr_fmt(fmt)	"reboot: " fmt

#include <linux/ctype.h>
#include <linux/export.h>
#include <linux/kexec.h>
#include <linux/kmod.h>
#include <linux/kmsg_dump.h>
#include <linux/reboot.h>
#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/syscore_ops.h>
#include <linux/uaccess.h>

/*
 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
 */

int C_A_D = 1;
struct pid *cad_pid;
EXPORT_SYMBOL(cad_pid);

#if defined(CONFIG_ARM) || defined(CONFIG_UNICORE32)
#define DEFAULT_REBOOT_MODE		= REBOOT_HARD
#else
#define DEFAULT_REBOOT_MODE
#endif
enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;

/*
 * This variable is used privately to keep track of whether or not
 * reboot_type is still set to its default value (i.e., reboot= hasn't
 * been set on the command line).  This is needed so that we can
 * suppress DMI scanning for reboot quirks.  Without it, it's
 * impossible to override a faulty reboot quirk without recompiling.
 */
int reboot_default = 1;
int reboot_cpu;
enum reboot_type reboot_type = BOOT_ACPI;
int reboot_force;

/*
 * If set, this is used for preparing the system to power off.
 */

void (*pm_power_off_prepare)(void);

/**
 *	emergency_restart - reboot the system
 *
 *	Without shutting down any hardware or taking any locks
 *	reboot the system.  This is called when we know we are in
 *	trouble so this is our best effort to reboot.  This is
 *	safe to call in interrupt context.
 */
void emergency_restart(void)
{
	kmsg_dump(KMSG_DUMP_EMERG);
	machine_emergency_restart();
}
EXPORT_SYMBOL_GPL(emergency_restart);

void kernel_restart_prepare(char *cmd)
{
	blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
	system_state = SYSTEM_RESTART;
	usermodehelper_disable();
	device_shutdown();
}

/**
 *	register_reboot_notifier - Register function to be called at reboot time
 *	@nb: Info about notifier function to be called
 *
 *	Registers a function with the list of functions
 *	to be called at reboot time.
 *
 *	Currently always returns zero, as blocking_notifier_chain_register()
 *	always returns zero.
 */
int register_reboot_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&reboot_notifier_list, nb);
}
EXPORT_SYMBOL(register_reboot_notifier);

/**
 *	unregister_reboot_notifier - Unregister previously registered reboot notifier
 *	@nb: Hook to be unregistered
 *
 *	Unregisters a previously registered reboot
 *	notifier function.
 *
 *	Returns zero on success, or %-ENOENT on failure.
 */
int unregister_reboot_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
}
EXPORT_SYMBOL(unregister_reboot_notifier);

static void devm_unregister_reboot_notifier(struct device *dev, void *res)
{
	WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
}

int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
{
	struct notifier_block **rcnb;
	int ret;

	rcnb = devres_alloc(devm_unregister_reboot_notifier,
			    sizeof(*rcnb), GFP_KERNEL);
	if (!rcnb)
		return -ENOMEM;

	ret = register_reboot_notifier(nb);
	if (!ret) {
		*rcnb = nb;
		devres_add(dev, rcnb);
	} else {
		devres_free(rcnb);
	}

	return ret;
}
EXPORT_SYMBOL(devm_register_reboot_notifier);

/*
 *	Notifier list for kernel code which wants to be called
 *	to restart the system.
 */
static ATOMIC_NOTIFIER_HEAD(restart_handler_list);

/**
 *	register_restart_handler - Register function to be called to reset
 *				   the system
 *	@nb: Info about handler function to be called
 *	@nb->priority:	Handler priority. Handlers should follow the
 *			following guidelines for setting priorities.
 *			0:	Restart handler of last resort,
 *				with limited restart capabilities
 *			128:	Default restart handler; use if no other
 *				restart handler is expected to be available,
 *				and/or if restart functionality is
 *				sufficient to restart the entire system
 *			255:	Highest priority restart handler, will
 *				preempt all other restart handlers
 *
 *	Registers a function with code to be called to restart the
 *	system.
 *
 *	Registered functions will be called from machine_restart as last
 *	step of the restart sequence (if the architecture specific
 *	machine_restart function calls do_kernel_restart - see below
 *	for details).
 *	Registered functions are expected to restart the system immediately.
 *	If more than one function is registered, the restart handler priority
 *	selects which function will be called first.
 *
 *	Restart handlers are expected to be registered from non-architecture
 *	code, typically from drivers. A typical use case would be a system
 *	where restart functionality is provided through a watchdog. Multiple
 *	restart handlers may exist; for example, one restart handler might
 *	restart the entire system, while another only restarts the CPU.
 *	In such cases, the restart handler which only restarts part of the
 *	hardware is expected to register with low priority to ensure that
 *	it only runs if no other means to restart the system is available.
 *
 *	Currently always returns zero, as atomic_notifier_chain_register()
 *	always returns zero.
 */
int register_restart_handler(struct notifier_block *nb)
{
	return atomic_notifier_chain_register(&restart_handler_list, nb);
}
EXPORT_SYMBOL(register_restart_handler);

/**
 *	unregister_restart_handler - Unregister previously registered
 *				     restart handler
 *	@nb: Hook to be unregistered
 *
 *	Unregisters a previously registered restart handler function.
 *
 *	Returns zero on success, or %-ENOENT on failure.
 */
int unregister_restart_handler(struct notifier_block *nb)
{
	return atomic_notifier_chain_unregister(&restart_handler_list, nb);
}
EXPORT_SYMBOL(unregister_restart_handler);

/**
 *	do_kernel_restart - Execute kernel restart handler call chain
 *
 *	Calls functions registered with register_restart_handler.
 *
 *	Expected to be called from machine_restart as last step of the restart
 *	sequence.
 *
 *	Restarts the system immediately if a restart handler function has been
 *	registered. Otherwise does nothing.
 */
void do_kernel_restart(char *cmd)
{
	atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
}

void migrate_to_reboot_cpu(void)
{
	/* The boot cpu is always logical cpu 0 */
	int cpu = reboot_cpu;

	cpu_hotplug_disable();

	/* Make certain the cpu I'm about to reboot on is online */
	if (!cpu_online(cpu))
		cpu = cpumask_first(cpu_online_mask);

	/* Prevent races with other tasks migrating this task */
	current->flags |= PF_NO_SETAFFINITY;

	/* Make certain I only run on the appropriate processor */
	set_cpus_allowed_ptr(current, cpumask_of(cpu));
}

/**
 *	kernel_restart - reboot the system
 *	@cmd: pointer to buffer containing command to execute for restart
 *		or %NULL
 *
 *	Shutdown everything and perform a clean reboot.
 *	This is not safe to call in interrupt context.
 */
void kernel_restart(char *cmd)
{
	kernel_restart_prepare(cmd);
	migrate_to_reboot_cpu();
	syscore_shutdown();
	if (!cmd)
		pr_emerg("Restarting system\n");
	else
		pr_emerg("Restarting system with command '%s'\n", cmd);
	kmsg_dump(KMSG_DUMP_RESTART);
	machine_restart(cmd);
}
EXPORT_SYMBOL_GPL(kernel_restart);

static void kernel_shutdown_prepare(enum system_states state)
{
	blocking_notifier_call_chain(&reboot_notifier_list,
		(state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
	system_state = state;
	usermodehelper_disable();
	device_shutdown();
}
/**
 *	kernel_halt - halt the system
 *
 *	Shutdown everything and perform a clean system halt.
 */
void kernel_halt(void)
{
	kernel_shutdown_prepare(SYSTEM_HALT);
	migrate_to_reboot_cpu();
	syscore_shutdown();
	pr_emerg("System halted\n");
	kmsg_dump(KMSG_DUMP_HALT);
	machine_halt();
}
EXPORT_SYMBOL_GPL(kernel_halt);

/**
 *	kernel_power_off - power_off the system
 *
 *	Shutdown everything and perform a clean system power_off.
 */
void kernel_power_off(void)
{
	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
	if (pm_power_off_prepare)
		pm_power_off_prepare();
	migrate_to_reboot_cpu();
	syscore_shutdown();
	pr_emerg("Power down\n");
	kmsg_dump(KMSG_DUMP_POWEROFF);
	machine_power_off();
}
EXPORT_SYMBOL_GPL(kernel_power_off);

static DEFINE_MUTEX(reboot_mutex);

/*
 * Reboot system call: for obvious reasons only root may call it,
 * and even root needs to set up some magic numbers in the registers
 * so that some mistake won't make this reboot the whole machine.
 * You can also set the meaning of the ctrl-alt-del-key here.
 *
 * reboot doesn't sync: do that yourself before calling this.
 */
SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
		void __user *, arg)
{
	struct pid_namespace *pid_ns = task_active_pid_ns(current);
	char buffer[256];
	int ret = 0;

	/* We only trust the superuser with rebooting the system. */
	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
		return -EPERM;

	/* For safety, we require "magic" arguments. */
	if (magic1 != LINUX_REBOOT_MAGIC1 ||
			(magic2 != LINUX_REBOOT_MAGIC2 &&
			magic2 != LINUX_REBOOT_MAGIC2A &&
			magic2 != LINUX_REBOOT_MAGIC2B &&
			magic2 != LINUX_REBOOT_MAGIC2C))
		return -EINVAL;

	/*
	 * If pid namespaces are enabled and the current task is in a child
	 * pid_namespace, the command is handled by reboot_pid_ns() which will
	 * call do_exit().
	 */
	ret = reboot_pid_ns(pid_ns, cmd);
	if (ret)
		return ret;

	/* Instead of trying to make the power_off code look like
	 * halt when pm_power_off is not set do it the easy way.
	 */
	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
		cmd = LINUX_REBOOT_CMD_HALT;

	mutex_lock(&reboot_mutex);
	switch (cmd) {
	case LINUX_REBOOT_CMD_RESTART:
		kernel_restart(NULL);
		break;

	case LINUX_REBOOT_CMD_CAD_ON:
		C_A_D = 1;
		break;

	case LINUX_REBOOT_CMD_CAD_OFF:
		C_A_D = 0;
		break;

	case LINUX_REBOOT_CMD_HALT:
		kernel_halt();
		do_exit(0);
		panic("cannot halt");

	case LINUX_REBOOT_CMD_POWER_OFF:
		kernel_power_off();
		do_exit(0);
		break;

	case LINUX_REBOOT_CMD_RESTART2:
		ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
		if (ret < 0) {
			ret = -EFAULT;
			break;
		}
		buffer[sizeof(buffer) - 1] = '\0';

		kernel_restart(buffer);
		break;

#ifdef CONFIG_KEXEC_CORE
	case LINUX_REBOOT_CMD_KEXEC:
		ret = kernel_kexec();
		break;
#endif

#ifdef CONFIG_HIBERNATION
	case LINUX_REBOOT_CMD_SW_SUSPEND:
		ret = hibernate();
		break;
#endif

	default:
		ret = -EINVAL;
		break;
	}
	mutex_unlock(&reboot_mutex);
	return ret;
}

static void deferred_cad(struct work_struct *dummy)
{
	kernel_restart(NULL);
}

/*
 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
 * As it's called within an interrupt, it may NOT sync: the only choice
 * is whether to reboot at once, or just ignore the ctrl-alt-del.
 */
void ctrl_alt_del(void)
{
	static DECLARE_WORK(cad_work, deferred_cad);

	if (C_A_D)
		schedule_work(&cad_work);
	else
		kill_cad_pid(SIGINT, 1);
}

char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
static const char reboot_cmd[] = "/sbin/reboot";

static int run_cmd(const char *cmd)
{
	char **argv;
	static char *envp[] = {
		"HOME=/",
		"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
		NULL
	};
	int ret;
	argv = argv_split(GFP_KERNEL, cmd, NULL);
	if (argv) {
		ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
		argv_free(argv);
	} else {
		ret = -ENOMEM;
	}

	return ret;
}

static int __orderly_reboot(void)
{
	int ret;

	ret = run_cmd(reboot_cmd);

	if (ret) {
		pr_warn("Failed to start orderly reboot: forcing the issue\n");
		emergency_sync();
		kernel_restart(NULL);
	}

	return ret;
}

static int __orderly_poweroff(bool force)
{
	int ret;

	ret = run_cmd(poweroff_cmd);

	if (ret && force) {
		pr_warn("Failed to start orderly shutdown: forcing the issue\n");

		/*
		 * I guess this should try to kick off some daemon to sync and
		 * poweroff asap.  Or not even bother syncing if we're doing an
		 * emergency shutdown?
		 */
		emergency_sync();
		kernel_power_off();
	}

	return ret;
}

static bool poweroff_force;

static void poweroff_work_func(struct work_struct *work)
{
	__orderly_poweroff(poweroff_force);
}

static DECLARE_WORK(poweroff_work, poweroff_work_func);

/**
 * orderly_poweroff - Trigger an orderly system poweroff
 * @force: force poweroff if command execution fails
 *
 * This may be called from any context to trigger a system shutdown.
 * If the orderly shutdown fails, it will force an immediate shutdown.
 */
void orderly_poweroff(bool force)
{
	if (force) /* do not override the pending "true" */
		poweroff_force = true;
	schedule_work(&poweroff_work);
}
EXPORT_SYMBOL_GPL(orderly_poweroff);

static void reboot_work_func(struct work_struct *work)
{
	__orderly_reboot();
}

static DECLARE_WORK(reboot_work, reboot_work_func);

/**
 * orderly_reboot - Trigger an orderly system reboot
 *
 * This may be called from any context to trigger a system reboot.
 * If the orderly reboot fails, it will force an immediate reboot.
 */
void orderly_reboot(void)
{
	schedule_work(&reboot_work);
}
EXPORT_SYMBOL_GPL(orderly_reboot);

static int __init reboot_setup(char *str)
{
	for (;;) {
		/*
		 * Having anything passed on the command line via
		 * reboot= will cause us to disable DMI checking
		 * below.
		 */
		reboot_default = 0;

		switch (*str) {
		case 'w':
			reboot_mode = REBOOT_WARM;
			break;

		case 'c':
			reboot_mode = REBOOT_COLD;
			break;

		case 'h':
			reboot_mode = REBOOT_HARD;
			break;

		case 's':
		{
			int rc;

			if (isdigit(*(str+1))) {
				rc = kstrtoint(str+1, 0, &reboot_cpu);
				if (rc)
					return rc;
			} else if (str[1] == 'm' && str[2] == 'p' &&
				   isdigit(*(str+3))) {
				rc = kstrtoint(str+3, 0, &reboot_cpu);
				if (rc)
					return rc;
			} else
				reboot_mode = REBOOT_SOFT;
			break;
		}
		case 'g':
			reboot_mode = REBOOT_GPIO;
			break;

		case 'b':
		case 'a':
		case 'k':
		case 't':
		case 'e':
		case 'p':
			reboot_type = *str;
			break;

		case 'f':
			reboot_force = 1;
			break;
		}

		str = strchr(str, ',');
		if (str)
			str++;
		else
			break;
	}
	return 1;
}
__setup("reboot=", reboot_setup);
Commit	Line	Data
15d94b82 RH	1	/*
	2	* linux/kernel/reboot.c
	3	*
	4	* Copyright (C) 2013 Linus Torvalds
	5	*/
	6
972ee83d RH	7	#define pr_fmt(fmt) "reboot: " fmt
972ee83d RH	8
1b3a5d02	9	#include <linux/ctype.h>
15d94b82 RH	10	#include <linux/export.h>
	11	#include <linux/kexec.h>
	12	#include <linux/kmod.h>
	13	#include <linux/kmsg_dump.h>
	14	#include <linux/reboot.h>
	15	#include <linux/suspend.h>
	16	#include <linux/syscalls.h>
	17	#include <linux/syscore_ops.h>
	18	#include <linux/uaccess.h>
	19
	20	/*
	21	* this indicates whether you can reboot with ctrl-alt-del: the default is yes
	22	*/
	23
	24	int C_A_D = 1;
	25	struct pid *cad_pid;
	26	EXPORT_SYMBOL(cad_pid);
	27
1b3a5d02 RH	28	#if defined(CONFIG_ARM) \|\| defined(CONFIG_UNICORE32)
	29	#define DEFAULT_REBOOT_MODE = REBOOT_HARD
	30	#else
	31	#define DEFAULT_REBOOT_MODE
	32	#endif
	33	enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
	34
e2f0b88e CL	35	/*
	36	* This variable is used privately to keep track of whether or not
	37	* reboot_type is still set to its default value (i.e., reboot= hasn't
	38	* been set on the command line). This is needed so that we can
	39	* suppress DMI scanning for reboot quirks. Without it, it's
	40	* impossible to override a faulty reboot quirk without recompiling.
	41	*/
	42	int reboot_default = 1;
1b3a5d02 RH	43	int reboot_cpu;
	44	enum reboot_type reboot_type = BOOT_ACPI;
	45	int reboot_force;
	46
15d94b82 RH	47	/*
	48	* If set, this is used for preparing the system to power off.
	49	*/
	50
	51	void (*pm_power_off_prepare)(void);
	52
	53	/**
	54	* emergency_restart - reboot the system
	55	*
	56	* Without shutting down any hardware or taking any locks
	57	* reboot the system. This is called when we know we are in
	58	* trouble so this is our best effort to reboot. This is
	59	* safe to call in interrupt context.
	60	*/
	61	void emergency_restart(void)
	62	{
	63	kmsg_dump(KMSG_DUMP_EMERG);
	64	machine_emergency_restart();
	65	}
	66	EXPORT_SYMBOL_GPL(emergency_restart);
	67
	68	void kernel_restart_prepare(char *cmd)
	69	{
	70	blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
	71	system_state = SYSTEM_RESTART;
	72	usermodehelper_disable();
	73	device_shutdown();
	74	}
	75
	76	/**
	77	* register_reboot_notifier - Register function to be called at reboot time
	78	* @nb: Info about notifier function to be called
	79	*
	80	* Registers a function with the list of functions
	81	* to be called at reboot time.
	82	*
	83	* Currently always returns zero, as blocking_notifier_chain_register()
	84	* always returns zero.
	85	*/
	86	int register_reboot_notifier(struct notifier_block *nb)
	87	{
	88	return blocking_notifier_chain_register(&reboot_notifier_list, nb);
	89	}
	90	EXPORT_SYMBOL(register_reboot_notifier);
	91
	92	/**
	93	* unregister_reboot_notifier - Unregister previously registered reboot notifier
	94	* @nb: Hook to be unregistered
	95	*
	96	* Unregisters a previously registered reboot
	97	* notifier function.
	98	*
	99	* Returns zero on success, or %-ENOENT on failure.
	100	*/
	101	int unregister_reboot_notifier(struct notifier_block *nb)
	102	{
	103	return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
	104	}
	105	EXPORT_SYMBOL(unregister_reboot_notifier);
	106
2d8364ba AS	107	static void devm_unregister_reboot_notifier(struct device dev, void res)
	108	{
	109	WARN_ON(unregister_reboot_notifier((struct notifier_block *)res));
	110	}
	111
	112	int devm_register_reboot_notifier(struct device dev, struct notifier_block nb)
	113	{
	114	struct notifier_block **rcnb;
	115	int ret;
	116
	117	rcnb = devres_alloc(devm_unregister_reboot_notifier,
	118	sizeof(*rcnb), GFP_KERNEL);
	119	if (!rcnb)
	120	return -ENOMEM;
	121
	122	ret = register_reboot_notifier(nb);
	123	if (!ret) {
	124	*rcnb = nb;
	125	devres_add(dev, rcnb);
	126	} else {
	127	devres_free(rcnb);
	128	}
	129
	130	return ret;
	131	}
	132	EXPORT_SYMBOL(devm_register_reboot_notifier);
	133
b63adb97 GR	134	/*
	135	* Notifier list for kernel code which wants to be called
	136	* to restart the system.
	137	*/
	138	static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
	139
	140	/**
	141	* register_restart_handler - Register function to be called to reset
	142	* the system
	143	* @nb: Info about handler function to be called
	144	* @nb->priority: Handler priority. Handlers should follow the
	145	* following guidelines for setting priorities.
	146	* 0: Restart handler of last resort,
	147	* with limited restart capabilities
	148	* 128: Default restart handler; use if no other
	149	* restart handler is expected to be available,
	150	* and/or if restart functionality is
	151	* sufficient to restart the entire system
	152	* 255: Highest priority restart handler, will
	153	* preempt all other restart handlers
	154	*
	155	* Registers a function with code to be called to restart the
	156	* system.
	157	*
	158	* Registered functions will be called from machine_restart as last
	159	* step of the restart sequence (if the architecture specific
	160	* machine_restart function calls do_kernel_restart - see below
	161	* for details).
	162	* Registered functions are expected to restart the system immediately.
	163	* If more than one function is registered, the restart handler priority
	164	* selects which function will be called first.
	165	*
	166	* Restart handlers are expected to be registered from non-architecture
	167	* code, typically from drivers. A typical use case would be a system
	168	* where restart functionality is provided through a watchdog. Multiple
	169	* restart handlers may exist; for example, one restart handler might
	170	* restart the entire system, while another only restarts the CPU.
	171	* In such cases, the restart handler which only restarts part of the
	172	* hardware is expected to register with low priority to ensure that
	173	* it only runs if no other means to restart the system is available.
	174	*
	175	* Currently always returns zero, as atomic_notifier_chain_register()
	176	* always returns zero.
	177	*/
	178	int register_restart_handler(struct notifier_block *nb)
	179	{
	180	return atomic_notifier_chain_register(&restart_handler_list, nb);
	181	}
	182	EXPORT_SYMBOL(register_restart_handler);
	183
	184	/**
	185	* unregister_restart_handler - Unregister previously registered
	186	* restart handler
	187	* @nb: Hook to be unregistered
	188	*
	189	* Unregisters a previously registered restart handler function.
	190	*
	191	* Returns zero on success, or %-ENOENT on failure.
	192	*/
	193	int unregister_restart_handler(struct notifier_block *nb)
	194	{
	195	return atomic_notifier_chain_unregister(&restart_handler_list, nb);
	196	}
	197	EXPORT_SYMBOL(unregister_restart_handler);
198
199	/**
200	* do_kernel_restart - Execute kernel restart handler call chain
201	*
202	* Calls functions registered with register_restart_handler.
203	*
204	* Expected to be called from machine_restart as last step of the restart
205	* sequence.
206	*
207	* Restarts the system immediately if a restart handler function has been
208	* registered. Otherwise does nothing.
209	*/
210	void do_kernel_restart(char *cmd)
211	{
212	atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
213	}
214
c97102ba	215	void migrate_to_reboot_cpu(void)
15d94b82 RH	216	{
15d94b82 RH	217	/* The boot cpu is always logical cpu 0 */
1b3a5d02	218	int cpu = reboot_cpu;
15d94b82 RH	219
	220	cpu_hotplug_disable();
	221
	222	/* Make certain the cpu I'm about to reboot on is online */
	223	if (!cpu_online(cpu))
	224	cpu = cpumask_first(cpu_online_mask);
	225
	226	/* Prevent races with other tasks migrating this task */
	227	current->flags \|= PF_NO_SETAFFINITY;
	228
	229	/* Make certain I only run on the appropriate processor */
	230	set_cpus_allowed_ptr(current, cpumask_of(cpu));
	231	}
	232
	233	/**
	234	* kernel_restart - reboot the system
	235	* @cmd: pointer to buffer containing command to execute for restart
	236	* or %NULL
	237	*
	238	* Shutdown everything and perform a clean reboot.
	239	* This is not safe to call in interrupt context.
	240	*/
	241	void kernel_restart(char *cmd)
	242	{
	243	kernel_restart_prepare(cmd);
	244	migrate_to_reboot_cpu();
	245	syscore_shutdown();
	246	if (!cmd)
972ee83d	247	pr_emerg("Restarting system\n");
15d94b82	248	else
972ee83d	249	pr_emerg("Restarting system with command '%s'\n", cmd);
15d94b82 RH	250	kmsg_dump(KMSG_DUMP_RESTART);
	251	machine_restart(cmd);
	252	}
	253	EXPORT_SYMBOL_GPL(kernel_restart);
	254
	255	static void kernel_shutdown_prepare(enum system_states state)
	256	{
	257	blocking_notifier_call_chain(&reboot_notifier_list,
972ee83d	258	(state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
15d94b82 RH	259	system_state = state;
	260	usermodehelper_disable();
	261	device_shutdown();
	262	}
	263	/**
	264	* kernel_halt - halt the system
	265	*
	266	* Shutdown everything and perform a clean system halt.
	267	*/
	268	void kernel_halt(void)
	269	{
	270	kernel_shutdown_prepare(SYSTEM_HALT);
	271	migrate_to_reboot_cpu();
	272	syscore_shutdown();
972ee83d	273	pr_emerg("System halted\n");
15d94b82 RH	274	kmsg_dump(KMSG_DUMP_HALT);
	275	machine_halt();
	276	}
15d94b82 RH	277	EXPORT_SYMBOL_GPL(kernel_halt);
	278
	279	/**
	280	* kernel_power_off - power_off the system
	281	*
	282	* Shutdown everything and perform a clean system power_off.
	283	*/
	284	void kernel_power_off(void)
	285	{
	286	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
	287	if (pm_power_off_prepare)
	288	pm_power_off_prepare();
	289	migrate_to_reboot_cpu();
	290	syscore_shutdown();
972ee83d	291	pr_emerg("Power down\n");
15d94b82 RH	292	kmsg_dump(KMSG_DUMP_POWEROFF);
	293	machine_power_off();
	294	}
	295	EXPORT_SYMBOL_GPL(kernel_power_off);
	296
	297	static DEFINE_MUTEX(reboot_mutex);
	298
	299	/*
	300	* Reboot system call: for obvious reasons only root may call it,
	301	* and even root needs to set up some magic numbers in the registers
	302	* so that some mistake won't make this reboot the whole machine.
	303	* You can also set the meaning of the ctrl-alt-del-key here.
	304	*
	305	* reboot doesn't sync: do that yourself before calling this.
	306	*/
	307	SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
	308	void __user *, arg)
	309	{
	310	struct pid_namespace *pid_ns = task_active_pid_ns(current);
	311	char buffer[256];
	312	int ret = 0;
	313
	314	/* We only trust the superuser with rebooting the system. */
	315	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
	316	return -EPERM;
	317
	318	/* For safety, we require "magic" arguments. */
	319	if (magic1 != LINUX_REBOOT_MAGIC1 \|\|
972ee83d RH	320	(magic2 != LINUX_REBOOT_MAGIC2 &&
972ee83d RH	321	magic2 != LINUX_REBOOT_MAGIC2A &&
15d94b82	322	magic2 != LINUX_REBOOT_MAGIC2B &&
972ee83d	323	magic2 != LINUX_REBOOT_MAGIC2C))
15d94b82 RH	324	return -EINVAL;
	325
	326	/*
	327	* If pid namespaces are enabled and the current task is in a child
	328	* pid_namespace, the command is handled by reboot_pid_ns() which will
	329	* call do_exit().
	330	*/
	331	ret = reboot_pid_ns(pid_ns, cmd);
	332	if (ret)
	333	return ret;
	334
	335	/* Instead of trying to make the power_off code look like
	336	* halt when pm_power_off is not set do it the easy way.
	337	*/
	338	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
	339	cmd = LINUX_REBOOT_CMD_HALT;
	340
	341	mutex_lock(&reboot_mutex);
	342	switch (cmd) {
	343	case LINUX_REBOOT_CMD_RESTART:
	344	kernel_restart(NULL);
	345	break;
	346
	347	case LINUX_REBOOT_CMD_CAD_ON:
	348	C_A_D = 1;
	349	break;
	350
	351	case LINUX_REBOOT_CMD_CAD_OFF:
	352	C_A_D = 0;
	353	break;
	354
	355	case LINUX_REBOOT_CMD_HALT:
	356	kernel_halt();
	357	do_exit(0);
	358	panic("cannot halt");
	359
	360	case LINUX_REBOOT_CMD_POWER_OFF:
	361	kernel_power_off();
	362	do_exit(0);
	363	break;
	364
	365	case LINUX_REBOOT_CMD_RESTART2:
972ee83d RH	366	ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
972ee83d RH	367	if (ret < 0) {
15d94b82 RH	368	ret = -EFAULT;
	369	break;
	370	}
	371	buffer[sizeof(buffer) - 1] = '\0';
	372
	373	kernel_restart(buffer);
	374	break;
	375
2965faa5	376	#ifdef CONFIG_KEXEC_CORE
15d94b82 RH	377	case LINUX_REBOOT_CMD_KEXEC:
	378	ret = kernel_kexec();
	379	break;
	380	#endif
	381
	382	#ifdef CONFIG_HIBERNATION
	383	case LINUX_REBOOT_CMD_SW_SUSPEND:
	384	ret = hibernate();
	385	break;
	386	#endif
	387
	388	default:
	389	ret = -EINVAL;
	390	break;
	391	}
	392	mutex_unlock(&reboot_mutex);
	393	return ret;
	394	}
	395
	396	static void deferred_cad(struct work_struct *dummy)
	397	{
	398	kernel_restart(NULL);
	399	}
	400
	401	/*
	402	* This function gets called by ctrl-alt-del - ie the keyboard interrupt.
	403	* As it's called within an interrupt, it may NOT sync: the only choice
	404	* is whether to reboot at once, or just ignore the ctrl-alt-del.
	405	*/
	406	void ctrl_alt_del(void)
	407	{
	408	static DECLARE_WORK(cad_work, deferred_cad);
	409
	410	if (C_A_D)
	411	schedule_work(&cad_work);
	412	else
	413	kill_cad_pid(SIGINT, 1);
	414	}
	415
	416	char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
7a54f46b	417	static const char reboot_cmd[] = "/sbin/reboot";
15d94b82	418
7a54f46b	419	static int run_cmd(const char *cmd)
15d94b82 RH	420	{
	421	char **argv;
	422	static char *envp[] = {
	423	"HOME=/",
	424	"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
	425	NULL
	426	};
	427	int ret;
7a54f46b	428	argv = argv_split(GFP_KERNEL, cmd, NULL);
15d94b82 RH	429	if (argv) {
	430	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
	431	argv_free(argv);
	432	} else {
15d94b82 RH	433	ret = -ENOMEM;
	434	}
	435
7a54f46b JS	436	return ret;
	437	}
	438
	439	static int __orderly_reboot(void)
	440	{
	441	int ret;
	442
	443	ret = run_cmd(reboot_cmd);
	444
	445	if (ret) {
	446	pr_warn("Failed to start orderly reboot: forcing the issue\n");
	447	emergency_sync();
	448	kernel_restart(NULL);
	449	}
	450
	451	return ret;
	452	}
	453
	454	static int __orderly_poweroff(bool force)
	455	{
	456	int ret;
	457
	458	ret = run_cmd(poweroff_cmd);
	459
15d94b82	460	if (ret && force) {
972ee83d	461	pr_warn("Failed to start orderly shutdown: forcing the issue\n");
7a54f46b	462
15d94b82 RH	463	/*
	464	* I guess this should try to kick off some daemon to sync and
	465	* poweroff asap. Or not even bother syncing if we're doing an
	466	* emergency shutdown?
	467	*/
	468	emergency_sync();
	469	kernel_power_off();
	470	}
	471
	472	return ret;
	473	}
	474
	475	static bool poweroff_force;
	476
	477	static void poweroff_work_func(struct work_struct *work)
	478	{
	479	__orderly_poweroff(poweroff_force);
	480	}
	481
	482	static DECLARE_WORK(poweroff_work, poweroff_work_func);
	483
	484	/**
	485	* orderly_poweroff - Trigger an orderly system poweroff
	486	* @force: force poweroff if command execution fails
	487	*
	488	* This may be called from any context to trigger a system shutdown.
	489	* If the orderly shutdown fails, it will force an immediate shutdown.
	490	*/
7a54f46b	491	void orderly_poweroff(bool force)
15d94b82 RH	492	{
	493	if (force) /* do not override the pending "true" */
	494	poweroff_force = true;
	495	schedule_work(&poweroff_work);
15d94b82 RH	496	}
15d94b82 RH	497	EXPORT_SYMBOL_GPL(orderly_poweroff);
1b3a5d02	498
7a54f46b JS	499	static void reboot_work_func(struct work_struct *work)
	500	{
	501	__orderly_reboot();
	502	}
	503
	504	static DECLARE_WORK(reboot_work, reboot_work_func);
	505
	506	/**
	507	* orderly_reboot - Trigger an orderly system reboot
	508	*
	509	* This may be called from any context to trigger a system reboot.
	510	* If the orderly reboot fails, it will force an immediate reboot.
	511	*/
	512	void orderly_reboot(void)
	513	{
	514	schedule_work(&reboot_work);
	515	}
	516	EXPORT_SYMBOL_GPL(orderly_reboot);
	517
1b3a5d02 RH	518	static int __init reboot_setup(char *str)
	519	{
	520	for (;;) {
	521	/*
	522	* Having anything passed on the command line via
	523	* reboot= will cause us to disable DMI checking
	524	* below.
	525	*/
	526	reboot_default = 0;
	527
	528	switch (*str) {
	529	case 'w':
	530	reboot_mode = REBOOT_WARM;
	531	break;
	532
	533	case 'c':
	534	reboot_mode = REBOOT_COLD;
	535	break;
	536
	537	case 'h':
	538	reboot_mode = REBOOT_HARD;
	539	break;
	540
	541	case 's':
616feab7 FF	542	{
	543	int rc;
	544
	545	if (isdigit(*(str+1))) {
	546	rc = kstrtoint(str+1, 0, &reboot_cpu);
	547	if (rc)
	548	return rc;
	549	} else if (str[1] == 'm' && str[2] == 'p' &&
	550	isdigit(*(str+3))) {
	551	rc = kstrtoint(str+3, 0, &reboot_cpu);
	552	if (rc)
	553	return rc;
	554	} else
1b3a5d02 RH	555	reboot_mode = REBOOT_SOFT;
1b3a5d02 RH	556	break;
616feab7	557	}
1b3a5d02 RH	558	case 'g':
	559	reboot_mode = REBOOT_GPIO;
	560	break;
	561
	562	case 'b':
	563	case 'a':
	564	case 'k':
	565	case 't':
	566	case 'e':
	567	case 'p':
	568	reboot_type = *str;
	569	break;
	570
	571	case 'f':
	572	reboot_force = 1;
	573	break;
	574	}
	575
	576	str = strchr(str, ',');
	577	if (str)
	578	str++;
	579	else
	580	break;
	581	}
	582	return 1;
	583	}
	584	__setup("reboot=", reboot_setup);