1 files changed, 768 insertions, 24 deletions

diff --git a/kernel/reboot.c b/kernel/reboot.c
index 491f1347bf43..b5a8569e5d81 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -7,6 +7,7 @@
 
 #define pr_fmt(fmt)	"reboot: " fmt
 
+#include <linux/atomic.h>
 #include <linux/ctype.h>
 #include <linux/export.h>
 #include <linux/kexec.h>
@@ -22,16 +23,17 @@
  * this indicates whether you can reboot with ctrl-alt-del: the default is yes
  */
 
-int C_A_D = 1;
+static int C_A_D = 1;
 struct pid *cad_pid;
 EXPORT_SYMBOL(cad_pid);
 
-#if defined(CONFIG_ARM) || defined(CONFIG_UNICORE32)
+#if defined(CONFIG_ARM)
 #define DEFAULT_REBOOT_MODE		= REBOOT_HARD
 #else
 #define DEFAULT_REBOOT_MODE
 #endif
 enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
+EXPORT_SYMBOL_GPL(reboot_mode);
 enum reboot_mode panic_reboot_mode = REBOOT_UNDEFINED;
 
 /*
@@ -46,12 +48,36 @@ int reboot_cpu;
 enum reboot_type reboot_type = BOOT_ACPI;
 int reboot_force;
 
+struct sys_off_handler {
+	struct notifier_block nb;
+	int (*sys_off_cb)(struct sys_off_data *data);
+	void *cb_data;
+	enum sys_off_mode mode;
+	bool blocking;
+	void *list;
+	struct device *dev;
+};
+
 /*
- * If set, this is used for preparing the system to power off.
+ * This variable is used to indicate if a halt was initiated instead of a
+ * reboot when the reboot call was invoked with LINUX_REBOOT_CMD_POWER_OFF, but
+ * the system cannot be powered off. This allowes kernel_halt() to notify users
+ * of that.
  */
+static bool poweroff_fallback_to_halt;
 
-void (*pm_power_off_prepare)(void);
-EXPORT_SYMBOL_GPL(pm_power_off_prepare);
+/*
+ * Temporary stub that prevents linkage failure while we're in process
+ * of removing all uses of legacy pm_power_off() around the kernel.
+ */
+void __weak (*pm_power_off)(void);
+
+/*
+ *	Notifier list for kernel code which wants to be called
+ *	at shutdown. This is used to stop any idling DMA operations
+ *	and the like.
+ */
+static BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
 
 /**
  *	emergency_restart - reboot the system
@@ -64,6 +90,7 @@ EXPORT_SYMBOL_GPL(pm_power_off_prepare);
 void emergency_restart(void)
 {
 	kmsg_dump(KMSG_DUMP_EMERG);
+	system_state = SYSTEM_RESTART;
 	machine_emergency_restart();
 }
 EXPORT_SYMBOL_GPL(emergency_restart);
@@ -233,6 +260,17 @@ void migrate_to_reboot_cpu(void)
 	set_cpus_allowed_ptr(current, cpumask_of(cpu));
 }
 
+/*
+ *	Notifier list for kernel code which wants to be called
+ *	to prepare system for restart.
+ */
+static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list);
+
+static void do_kernel_restart_prepare(void)
+{
+	blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL);
+}
+
 /**
  *	kernel_restart - reboot the system
  *	@cmd: pointer to buffer containing command to execute for restart
@@ -244,6 +282,7 @@ void migrate_to_reboot_cpu(void)
 void kernel_restart(char *cmd)
 {
 	kernel_restart_prepare(cmd);
+	do_kernel_restart_prepare();
 	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	if (!cmd)
@@ -273,12 +312,386 @@ void kernel_halt(void)
 	kernel_shutdown_prepare(SYSTEM_HALT);
 	migrate_to_reboot_cpu();
 	syscore_shutdown();
-	pr_emerg("System halted\n");
+	if (poweroff_fallback_to_halt)
+		pr_emerg("Power off not available: System halted instead\n");
+	else
+		pr_emerg("System halted\n");
 	kmsg_dump(KMSG_DUMP_SHUTDOWN);
 	machine_halt();
 }
 EXPORT_SYMBOL_GPL(kernel_halt);
 
+/*
+ *	Notifier list for kernel code which wants to be called
+ *	to prepare system for power off.
+ */
+static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list);
+
+/*
+ *	Notifier list for kernel code which wants to be called
+ *	to power off system.
+ */
+static ATOMIC_NOTIFIER_HEAD(power_off_handler_list);
+
+static int sys_off_notify(struct notifier_block *nb,
+			  unsigned long mode, void *cmd)
+{
+	struct sys_off_handler *handler;
+	struct sys_off_data data = {};
+
+	handler = container_of(nb, struct sys_off_handler, nb);
+	data.cb_data = handler->cb_data;
+	data.mode = mode;
+	data.cmd = cmd;
+	data.dev = handler->dev;
+
+	return handler->sys_off_cb(&data);
+}
+
+static struct sys_off_handler platform_sys_off_handler;
+
+static struct sys_off_handler *alloc_sys_off_handler(int priority)
+{
+	struct sys_off_handler *handler;
+	gfp_t flags;
+
+	/*
+	 * Platforms like m68k can't allocate sys_off handler dynamically
+	 * at the early boot time because memory allocator isn't available yet.
+	 */
+	if (priority == SYS_OFF_PRIO_PLATFORM) {
+		handler = &platform_sys_off_handler;
+		if (handler->cb_data)
+			return ERR_PTR(-EBUSY);
+	} else {
+		if (system_state > SYSTEM_RUNNING)
+			flags = GFP_ATOMIC;
+		else
+			flags = GFP_KERNEL;
+
+		handler = kzalloc(sizeof(*handler), flags);
+		if (!handler)
+			return ERR_PTR(-ENOMEM);
+	}
+
+	return handler;
+}
+
+static void free_sys_off_handler(struct sys_off_handler *handler)
+{
+	if (handler == &platform_sys_off_handler)
+		memset(handler, 0, sizeof(*handler));
+	else
+		kfree(handler);
+}
+
+/**
+ *	register_sys_off_handler - Register sys-off handler
+ *	@mode: Sys-off mode
+ *	@priority: Handler priority
+ *	@callback: Callback function
+ *	@cb_data: Callback argument
+ *
+ *	Registers system power-off or restart handler that will be invoked
+ *	at the step corresponding to the given sys-off mode. Handler's callback
+ *	should return NOTIFY_DONE to permit execution of the next handler in
+ *	the call chain or NOTIFY_STOP to break the chain (in error case for
+ *	example).
+ *
+ *	Multiple handlers can be registered at the default priority level.
+ *
+ *	Only one handler can be registered at the non-default priority level,
+ *	otherwise ERR_PTR(-EBUSY) is returned.
+ *
+ *	Returns a new instance of struct sys_off_handler on success, or
+ *	an ERR_PTR()-encoded error code otherwise.
+ */
+struct sys_off_handler *
+register_sys_off_handler(enum sys_off_mode mode,
+			 int priority,
+			 int (*callback)(struct sys_off_data *data),
+			 void *cb_data)
+{
+	struct sys_off_handler *handler;
+	int err;
+
+	handler = alloc_sys_off_handler(priority);
+	if (IS_ERR(handler))
+		return handler;
+
+	switch (mode) {
+	case SYS_OFF_MODE_POWER_OFF_PREPARE:
+		handler->list = &power_off_prep_handler_list;
+		handler->blocking = true;
+		break;
+
+	case SYS_OFF_MODE_POWER_OFF:
+		handler->list = &power_off_handler_list;
+		break;
+
+	case SYS_OFF_MODE_RESTART_PREPARE:
+		handler->list = &restart_prep_handler_list;
+		handler->blocking = true;
+		break;
+
+	case SYS_OFF_MODE_RESTART:
+		handler->list = &restart_handler_list;
+		break;
+
+	default:
+		free_sys_off_handler(handler);
+		return ERR_PTR(-EINVAL);
+	}
+
+	handler->nb.notifier_call = sys_off_notify;
+	handler->nb.priority = priority;
+	handler->sys_off_cb = callback;
+	handler->cb_data = cb_data;
+	handler->mode = mode;
+
+	if (handler->blocking) {
+		if (priority == SYS_OFF_PRIO_DEFAULT)
+			err = blocking_notifier_chain_register(handler->list,
+							       &handler->nb);
+		else
+			err = blocking_notifier_chain_register_unique_prio(handler->list,
+									   &handler->nb);
+	} else {
+		if (priority == SYS_OFF_PRIO_DEFAULT)
+			err = atomic_notifier_chain_register(handler->list,
+							     &handler->nb);
+		else
+			err = atomic_notifier_chain_register_unique_prio(handler->list,
+									 &handler->nb);
+	}
+
+	if (err) {
+		free_sys_off_handler(handler);
+		return ERR_PTR(err);
+	}
+
+	return handler;
+}
+EXPORT_SYMBOL_GPL(register_sys_off_handler);
+
+/**
+ *	unregister_sys_off_handler - Unregister sys-off handler
+ *	@handler: Sys-off handler
+ *
+ *	Unregisters given sys-off handler.
+ */
+void unregister_sys_off_handler(struct sys_off_handler *handler)
+{
+	int err;
+
+	if (IS_ERR_OR_NULL(handler))
+		return;
+
+	if (handler->blocking)
+		err = blocking_notifier_chain_unregister(handler->list,
+							 &handler->nb);
+	else
+		err = atomic_notifier_chain_unregister(handler->list,
+						       &handler->nb);
+
+	/* sanity check, shall never happen */
+	WARN_ON(err);
+
+	free_sys_off_handler(handler);
+}
+EXPORT_SYMBOL_GPL(unregister_sys_off_handler);
+
+static void devm_unregister_sys_off_handler(void *data)
+{
+	struct sys_off_handler *handler = data;
+
+	unregister_sys_off_handler(handler);
+}
+
+/**
+ *	devm_register_sys_off_handler - Register sys-off handler
+ *	@dev: Device that registers handler
+ *	@mode: Sys-off mode
+ *	@priority: Handler priority
+ *	@callback: Callback function
+ *	@cb_data: Callback argument
+ *
+ *	Registers resource-managed sys-off handler.
+ *
+ *	Returns zero on success, or error code on failure.
+ */
+int devm_register_sys_off_handler(struct device *dev,
+				  enum sys_off_mode mode,
+				  int priority,
+				  int (*callback)(struct sys_off_data *data),
+				  void *cb_data)
+{
+	struct sys_off_handler *handler;
+
+	handler = register_sys_off_handler(mode, priority, callback, cb_data);
+	if (IS_ERR(handler))
+		return PTR_ERR(handler);
+	handler->dev = dev;
+
+	return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler,
+					handler);
+}
+EXPORT_SYMBOL_GPL(devm_register_sys_off_handler);
+
+/**
+ *	devm_register_power_off_handler - Register power-off handler
+ *	@dev: Device that registers callback
+ *	@callback: Callback function
+ *	@cb_data: Callback's argument
+ *
+ *	Registers resource-managed sys-off handler with a default priority
+ *	and using power-off mode.
+ *
+ *	Returns zero on success, or error code on failure.
+ */
+int devm_register_power_off_handler(struct device *dev,
+				    int (*callback)(struct sys_off_data *data),
+				    void *cb_data)
+{
+	return devm_register_sys_off_handler(dev,
+					     SYS_OFF_MODE_POWER_OFF,
+					     SYS_OFF_PRIO_DEFAULT,
+					     callback, cb_data);
+}
+EXPORT_SYMBOL_GPL(devm_register_power_off_handler);
+
+/**
+ *	devm_register_restart_handler - Register restart handler
+ *	@dev: Device that registers callback
+ *	@callback: Callback function
+ *	@cb_data: Callback's argument
+ *
+ *	Registers resource-managed sys-off handler with a default priority
+ *	and using restart mode.
+ *
+ *	Returns zero on success, or error code on failure.
+ */
+int devm_register_restart_handler(struct device *dev,
+				  int (*callback)(struct sys_off_data *data),
+				  void *cb_data)
+{
+	return devm_register_sys_off_handler(dev,
+					     SYS_OFF_MODE_RESTART,
+					     SYS_OFF_PRIO_DEFAULT,
+					     callback, cb_data);
+}
+EXPORT_SYMBOL_GPL(devm_register_restart_handler);
+
+static struct sys_off_handler *platform_power_off_handler;
+
+static int platform_power_off_notify(struct sys_off_data *data)
+{
+	void (*platform_power_power_off_cb)(void) = data->cb_data;
+
+	platform_power_power_off_cb();
+
+	return NOTIFY_DONE;
+}
+
+/**
+ *	register_platform_power_off - Register platform-level power-off callback
+ *	@power_off: Power-off callback
+ *
+ *	Registers power-off callback that will be called as last step
+ *	of the power-off sequence. This callback is expected to be invoked
+ *	for the last resort. Only one platform power-off callback is allowed
+ *	to be registered at a time.
+ *
+ *	Returns zero on success, or error code on failure.
+ */
+int register_platform_power_off(void (*power_off)(void))
+{
+	struct sys_off_handler *handler;
+
+	handler = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
+					   SYS_OFF_PRIO_PLATFORM,
+					   platform_power_off_notify,
+					   power_off);
+	if (IS_ERR(handler))
+		return PTR_ERR(handler);
+
+	platform_power_off_handler = handler;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(register_platform_power_off);
+
+/**
+ *	unregister_platform_power_off - Unregister platform-level power-off callback
+ *	@power_off: Power-off callback
+ *
+ *	Unregisters previously registered platform power-off callback.
+ */
+void unregister_platform_power_off(void (*power_off)(void))
+{
+	if (platform_power_off_handler &&
+	    platform_power_off_handler->cb_data == power_off) {
+		unregister_sys_off_handler(platform_power_off_handler);
+		platform_power_off_handler = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(unregister_platform_power_off);
+
+static int legacy_pm_power_off(struct sys_off_data *data)
+{
+	if (pm_power_off)
+		pm_power_off();
+
+	return NOTIFY_DONE;
+}
+
+static void do_kernel_power_off_prepare(void)
+{
+	blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL);
+}
+
+/**
+ *	do_kernel_power_off - Execute kernel power-off handler call chain
+ *
+ *	Expected to be called as last step of the power-off sequence.
+ *
+ *	Powers off the system immediately if a power-off handler function has
+ *	been registered. Otherwise does nothing.
+ */
+void do_kernel_power_off(void)
+{
+	struct sys_off_handler *sys_off = NULL;
+
+	/*
+	 * Register sys-off handlers for legacy PM callback. This allows
+	 * legacy PM callbacks temporary co-exist with the new sys-off API.
+	 *
+	 * TODO: Remove legacy handlers once all legacy PM users will be
+	 *       switched to the sys-off based APIs.
+	 */
+	if (pm_power_off)
+		sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
+						   SYS_OFF_PRIO_DEFAULT,
+						   legacy_pm_power_off, NULL);
+
+	atomic_notifier_call_chain(&power_off_handler_list, 0, NULL);
+
+	unregister_sys_off_handler(sys_off);
+}
+
+/**
+ *	kernel_can_power_off - check whether system can be powered off
+ *
+ *	Returns true if power-off handler is registered and system can be
+ *	powered off, false otherwise.
+ */
+bool kernel_can_power_off(void)
+{
+	return !atomic_notifier_call_chain_is_empty(&power_off_handler_list) ||
+		pm_power_off;
+}
+EXPORT_SYMBOL_GPL(kernel_can_power_off);
+
 /**
  *	kernel_power_off - power_off the system
  *
@@ -287,8 +700,7 @@ EXPORT_SYMBOL_GPL(kernel_halt);
 void kernel_power_off(void)
 {
 	kernel_shutdown_prepare(SYSTEM_POWER_OFF);
-	if (pm_power_off_prepare)
-		pm_power_off_prepare();
+	do_kernel_power_off_prepare();
 	migrate_to_reboot_cpu();
 	syscore_shutdown();
 	pr_emerg("Power down\n");
@@ -338,8 +750,10 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 	/* 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)
+	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off()) {
+		poweroff_fallback_to_halt = true;
 		cmd = LINUX_REBOOT_CMD_HALT;
+	}
 
 	mutex_lock(&system_transition_mutex);
 	switch (cmd) {
@@ -358,7 +772,6 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 	case LINUX_REBOOT_CMD_HALT:
 		kernel_halt();
 		do_exit(0);
-		panic("cannot halt");
 
 	case LINUX_REBOOT_CMD_POWER_OFF:
 		kernel_power_off();
@@ -416,7 +829,8 @@ void ctrl_alt_del(void)
 		kill_cad_pid(SIGINT, 1);
 }
 
-char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
+#define POWEROFF_CMD_PATH_LEN  256
+static char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
 static const char reboot_cmd[] = "/sbin/reboot";
 
 static int run_cmd(const char *cmd)
@@ -518,6 +932,90 @@ void orderly_reboot(void)
 }
 EXPORT_SYMBOL_GPL(orderly_reboot);
 
+/**
+ * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay
+ * @work: work_struct associated with the emergency poweroff function
+ *
+ * This function is called in very critical situations to force
+ * a kernel poweroff after a configurable timeout value.
+ */
+static void hw_failure_emergency_poweroff_func(struct work_struct *work)
+{
+	/*
+	 * We have reached here after the emergency shutdown waiting period has
+	 * expired. This means orderly_poweroff has not been able to shut off
+	 * the system for some reason.
+	 *
+	 * Try to shut down the system immediately using kernel_power_off
+	 * if populated
+	 */
+	pr_emerg("Hardware protection timed-out. Trying forced poweroff\n");
+	kernel_power_off();
+
+	/*
+	 * Worst of the worst case trigger emergency restart
+	 */
+	pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n");
+	emergency_restart();
+}
+
+static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
+			    hw_failure_emergency_poweroff_func);
+
+/**
+ * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
+ *
+ * This may be called from any critical situation to trigger a system shutdown
+ * after a given period of time. If time is negative this is not scheduled.
+ */
+static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
+{
+	if (poweroff_delay_ms <= 0)
+		return;
+	schedule_delayed_work(&hw_failure_emergency_poweroff_work,
+			      msecs_to_jiffies(poweroff_delay_ms));
+}
+
+/**
+ * __hw_protection_shutdown - Trigger an emergency system shutdown or reboot
+ *
+ * @reason:		Reason of emergency shutdown or reboot to be printed.
+ * @ms_until_forced:	Time to wait for orderly shutdown or reboot before
+ *			triggering it. Negative value disables the forced
+ *			shutdown or reboot.
+ * @shutdown:		If true, indicates that a shutdown will happen
+ *			after the critical tempeature is reached.
+ *			If false, indicates that a reboot will happen
+ *			after the critical tempeature is reached.
+ *
+ * Initiate an emergency system shutdown or reboot in order to protect
+ * hardware from further damage. Usage examples include a thermal protection.
+ * NOTE: The request is ignored if protection shutdown or reboot is already
+ * pending even if the previous request has given a large timeout for forced
+ * shutdown/reboot.
+ */
+void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shutdown)
+{
+	static atomic_t allow_proceed = ATOMIC_INIT(1);
+
+	pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
+
+	/* Shutdown should be initiated only once. */
+	if (!atomic_dec_and_test(&allow_proceed))
+		return;
+
+	/*
+	 * Queue a backup emergency shutdown in the event of
+	 * orderly_poweroff failure
+	 */
+	hw_failure_emergency_poweroff(ms_until_forced);
+	if (shutdown)
+		orderly_poweroff(true);
+	else
+		orderly_reboot();
+}
+EXPORT_SYMBOL_GPL(__hw_protection_shutdown);
+
 static int __init reboot_setup(char *str)
 {
 	for (;;) {
@@ -551,22 +1049,26 @@ static int __init reboot_setup(char *str)
 			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;
+			/*
+			 * reboot_cpu is s[mp]#### with #### being the processor
+			 * to be used for rebooting. Skip 's' or 'smp' prefix.
+			 */
+			str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
+
+			if (isdigit(str[0])) {
+				int cpu = simple_strtoul(str, NULL, 0);
+
+				if (cpu >= num_possible_cpus()) {
+					pr_err("Ignoring the CPU number in reboot= option. "
+					"CPU %d exceeds possible cpu number %d\n",
+					cpu, num_possible_cpus());
+					break;
+				}
+				reboot_cpu = cpu;
 			} else
 				*mode = REBOOT_SOFT;
 			break;
-		}
+
 		case 'g':
 			*mode = REBOOT_GPIO;
 			break;
@@ -594,3 +1096,245 @@ static int __init reboot_setup(char *str)
 	return 1;
 }
 __setup("reboot=", reboot_setup);
+
+#ifdef CONFIG_SYSFS
+
+#define REBOOT_COLD_STR		"cold"
+#define REBOOT_WARM_STR		"warm"
+#define REBOOT_HARD_STR		"hard"
+#define REBOOT_SOFT_STR		"soft"
+#define REBOOT_GPIO_STR		"gpio"
+#define REBOOT_UNDEFINED_STR	"undefined"
+
+#define BOOT_TRIPLE_STR		"triple"
+#define BOOT_KBD_STR		"kbd"
+#define BOOT_BIOS_STR		"bios"
+#define BOOT_ACPI_STR		"acpi"
+#define BOOT_EFI_STR		"efi"
+#define BOOT_PCI_STR		"pci"
+
+static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	const char *val;
+
+	switch (reboot_mode) {
+	case REBOOT_COLD:
+		val = REBOOT_COLD_STR;
+		break;
+	case REBOOT_WARM:
+		val = REBOOT_WARM_STR;
+		break;
+	case REBOOT_HARD:
+		val = REBOOT_HARD_STR;
+		break;
+	case REBOOT_SOFT:
+		val = REBOOT_SOFT_STR;
+		break;
+	case REBOOT_GPIO:
+		val = REBOOT_GPIO_STR;
+		break;
+	default:
+		val = REBOOT_UNDEFINED_STR;
+	}
+
+	return sysfs_emit(buf, "%s\n", val);
+}
+static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr,
+			  const char *buf, size_t count)
+{
+	if (!capable(CAP_SYS_BOOT))
+		return -EPERM;
+
+	if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR)))
+		reboot_mode = REBOOT_COLD;
+	else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR)))
+		reboot_mode = REBOOT_WARM;
+	else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR)))
+		reboot_mode = REBOOT_HARD;
+	else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR)))
+		reboot_mode = REBOOT_SOFT;
+	else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR)))
+		reboot_mode = REBOOT_GPIO;
+	else
+		return -EINVAL;
+
+	reboot_default = 0;
+
+	return count;
+}
+static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
+
+#ifdef CONFIG_X86
+static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", reboot_force);
+}
+static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
+			  const char *buf, size_t count)
+{
+	bool res;
+
+	if (!capable(CAP_SYS_BOOT))
+		return -EPERM;
+
+	if (kstrtobool(buf, &res))
+		return -EINVAL;
+
+	reboot_default = 0;
+	reboot_force = res;
+
+	return count;
+}
+static struct kobj_attribute reboot_force_attr = __ATTR_RW(force);
+
+static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	const char *val;
+
+	switch (reboot_type) {
+	case BOOT_TRIPLE:
+		val = BOOT_TRIPLE_STR;
+		break;
+	case BOOT_KBD:
+		val = BOOT_KBD_STR;
+		break;
+	case BOOT_BIOS:
+		val = BOOT_BIOS_STR;
+		break;
+	case BOOT_ACPI:
+		val = BOOT_ACPI_STR;
+		break;
+	case BOOT_EFI:
+		val = BOOT_EFI_STR;
+		break;
+	case BOOT_CF9_FORCE:
+		val = BOOT_PCI_STR;
+		break;
+	default:
+		val = REBOOT_UNDEFINED_STR;
+	}
+
+	return sysfs_emit(buf, "%s\n", val);
+}
+static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr,
+			  const char *buf, size_t count)
+{
+	if (!capable(CAP_SYS_BOOT))
+		return -EPERM;
+
+	if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR)))
+		reboot_type = BOOT_TRIPLE;
+	else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR)))
+		reboot_type = BOOT_KBD;
+	else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR)))
+		reboot_type = BOOT_BIOS;
+	else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR)))
+		reboot_type = BOOT_ACPI;
+	else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR)))
+		reboot_type = BOOT_EFI;
+	else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR)))
+		reboot_type = BOOT_CF9_FORCE;
+	else
+		return -EINVAL;
+
+	reboot_default = 0;
+
+	return count;
+}
+static struct kobj_attribute reboot_type_attr = __ATTR_RW(type);
+#endif
+
+#ifdef CONFIG_SMP
+static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", reboot_cpu);
+}
+static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr,
+			  const char *buf, size_t count)
+{
+	unsigned int cpunum;
+	int rc;
+
+	if (!capable(CAP_SYS_BOOT))
+		return -EPERM;
+
+	rc = kstrtouint(buf, 0, &cpunum);
+
+	if (rc)
+		return rc;
+
+	if (cpunum >= num_possible_cpus())
+		return -ERANGE;
+
+	reboot_default = 0;
+	reboot_cpu = cpunum;
+
+	return count;
+}
+static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu);
+#endif
+
+static struct attribute *reboot_attrs[] = {
+	&reboot_mode_attr.attr,
+#ifdef CONFIG_X86
+	&reboot_force_attr.attr,
+	&reboot_type_attr.attr,
+#endif
+#ifdef CONFIG_SMP
+	&reboot_cpu_attr.attr,
+#endif
+	NULL,
+};
+
+#ifdef CONFIG_SYSCTL
+static const struct ctl_table kern_reboot_table[] = {
+	{
+		.procname       = "poweroff_cmd",
+		.data           = &poweroff_cmd,
+		.maxlen         = POWEROFF_CMD_PATH_LEN,
+		.mode           = 0644,
+		.proc_handler   = proc_dostring,
+	},
+	{
+		.procname       = "ctrl-alt-del",
+		.data           = &C_A_D,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec,
+	},
+};
+
+static void __init kernel_reboot_sysctls_init(void)
+{
+	register_sysctl_init("kernel", kern_reboot_table);
+}
+#else
+#define kernel_reboot_sysctls_init() do { } while (0)
+#endif /* CONFIG_SYSCTL */
+
+static const struct attribute_group reboot_attr_group = {
+	.attrs = reboot_attrs,
+};
+
+static int __init reboot_ksysfs_init(void)
+{
+	struct kobject *reboot_kobj;
+	int ret;
+
+	reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);
+	if (!reboot_kobj)
+		return -ENOMEM;
+
+	ret = sysfs_create_group(reboot_kobj, &reboot_attr_group);
+	if (ret) {
+		kobject_put(reboot_kobj);
+		return ret;
+	}
+
+	kernel_reboot_sysctls_init();
+
+	return 0;
+}
+late_initcall(reboot_ksysfs_init);
+
+#endif