1 // SPDX-License-Identifier: GPL-2.0-only
3  *  linux/kernel/reboot.c
8 #define pr_fmt(fmt)	"reboot: " fmt
16 #include <linux/reboot.h>
23  * this indicates whether you can reboot with ctrl-alt-del: the default is yes
41  * reboot_type is still set to its default value (i.e., reboot= hasn't
43  * suppress DMI scanning for reboot quirks.  Without it, it's
44  * impossible to override a faulty reboot quirk without recompiling.
55 	enum sys_off_mode mode;  member
63  * reboot when the reboot call was invoked with LINUX_REBOOT_CMD_POWER_OFF, but
83  *	emergency_restart - reboot the system
86  *	reboot the system.  This is called when we know we are in
87  *	trouble so this is our best effort to reboot.  This is
107  *	register_reboot_notifier - Register function to be called at reboot time
111  *	to be called at reboot time.
123  *	unregister_reboot_notifier - Unregister previously registered reboot notifier
126  *	Unregisters a previously registered reboot
129  *	Returns zero on success, or %-ENOENT on failure.
150 		return -ENOMEM;  in devm_register_reboot_notifier()
171  *	register_restart_handler - Register function to be called to reset
174  *	@nb->priority:	Handler priority. Handlers should follow the
190  *	machine_restart function calls do_kernel_restart - see below
196  *	Restart handlers are expected to be registered from non-architecture
215  *	unregister_restart_handler - Unregister previously registered
221  *	Returns zero on success, or %-ENOENT on failure.
230  *	do_kernel_restart - Execute kernel restart handler call chain
252 	/* Make certain the cpu I'm about to reboot on is online */  in migrate_to_reboot_cpu()
257 	current->flags |= PF_NO_SETAFFINITY;  in migrate_to_reboot_cpu()
275  *	kernel_restart - reboot the system
279  *	Shutdown everything and perform a clean reboot.
306  *	kernel_halt - halt the system
337 			  unsigned long mode, void *cmd)  in sys_off_notify()  argument
343 	data.cb_data = handler->cb_data;  in sys_off_notify()
344 	data.mode = mode;  in sys_off_notify()
346 	data.dev = handler->dev;  in sys_off_notify()
348 	return handler->sys_off_cb(&data);  in sys_off_notify()
364 		if (handler->cb_data)  in alloc_sys_off_handler()
365 			return ERR_PTR(-EBUSY);  in alloc_sys_off_handler()
374 			return ERR_PTR(-ENOMEM);  in alloc_sys_off_handler()
389  *	register_sys_off_handler - Register sys-off handler
390  *	@mode: Sys-off mode
395  *	Registers system power-off or restart handler that will be invoked
396  *	at the step corresponding to the given sys-off mode. Handler's callback
403  *	Only one handler can be registered at the non-default priority level,
404  *	otherwise ERR_PTR(-EBUSY) is returned.
407  *	an ERR_PTR()-encoded error code otherwise.
410 register_sys_off_handler(enum sys_off_mode mode,  in register_sys_off_handler()  argument
422 	switch (mode) {  in register_sys_off_handler()
424 		handler->list = &power_off_prep_handler_list;  in register_sys_off_handler()
425 		handler->blocking = true;  in register_sys_off_handler()
429 		handler->list = &power_off_handler_list;  in register_sys_off_handler()
433 		handler->list = &restart_prep_handler_list;  in register_sys_off_handler()
434 		handler->blocking = true;  in register_sys_off_handler()
438 		handler->list = &restart_handler_list;  in register_sys_off_handler()
443 		return ERR_PTR(-EINVAL);  in register_sys_off_handler()
446 	handler->nb.notifier_call = sys_off_notify;  in register_sys_off_handler()
447 	handler->nb.priority = priority;  in register_sys_off_handler()
448 	handler->sys_off_cb = callback;  in register_sys_off_handler()
449 	handler->cb_data = cb_data;  in register_sys_off_handler()
450 	handler->mode = mode;  in register_sys_off_handler()
452 	if (handler->blocking) {  in register_sys_off_handler()
454 			err = blocking_notifier_chain_register(handler->list,  in register_sys_off_handler()
455 							       &handler->nb);  in register_sys_off_handler()
457 			err = blocking_notifier_chain_register_unique_prio(handler->list,  in register_sys_off_handler()
458 									   &handler->nb);  in register_sys_off_handler()
461 			err = atomic_notifier_chain_register(handler->list,  in register_sys_off_handler()
462 							     &handler->nb);  in register_sys_off_handler()
464 			err = atomic_notifier_chain_register_unique_prio(handler->list,  in register_sys_off_handler()
465 									 &handler->nb);  in register_sys_off_handler()
478  *	unregister_sys_off_handler - Unregister sys-off handler
479  *	@handler: Sys-off handler
481  *	Unregisters given sys-off handler.
490 	if (handler->blocking)  in unregister_sys_off_handler()
491 		err = blocking_notifier_chain_unregister(handler->list,  in unregister_sys_off_handler()
492 							 &handler->nb);  in unregister_sys_off_handler()
494 		err = atomic_notifier_chain_unregister(handler->list,  in unregister_sys_off_handler()
495 						       &handler->nb);  in unregister_sys_off_handler()
512  *	devm_register_sys_off_handler - Register sys-off handler
514  *	@mode: Sys-off mode
519  *	Registers resource-managed sys-off handler.
524 				  enum sys_off_mode mode,  in devm_register_sys_off_handler()  argument
531 	handler = register_sys_off_handler(mode, priority, callback, cb_data);  in devm_register_sys_off_handler()
534 	handler->dev = dev;  in devm_register_sys_off_handler()
542  *	devm_register_power_off_handler - Register power-off handler
547  *	Registers resource-managed sys-off handler with a default priority
548  *	and using power-off mode.
564  *	devm_register_restart_handler - Register restart handler
569  *	Registers resource-managed sys-off handler with a default priority
570  *	and using restart mode.
589 	void (*platform_power_power_off_cb)(void) = data->cb_data;  in platform_power_off_notify()
597  *	register_platform_power_off - Register platform-level power-off callback
598  *	@power_off: Power-off callback
600  *	Registers power-off callback that will be called as last step
601  *	of the power-off sequence. This callback is expected to be invoked
602  *	for the last resort. Only one platform power-off callback is allowed
625  *	unregister_platform_power_off - Unregister platform-level power-off callback
626  *	@power_off: Power-off callback
628  *	Unregisters previously registered platform power-off callback.
633 	    platform_power_off_handler->cb_data == power_off) {  in unregister_platform_power_off()
654  *	do_kernel_power_off - Execute kernel power-off handler call chain
656  *	Expected to be called as last step of the power-off sequence.
658  *	Powers off the system immediately if a power-off handler function has
666 	 * Register sys-off handlers for legacy PM callback. This allows  in do_kernel_power_off()
667 	 * legacy PM callbacks temporary co-exist with the new sys-off API.  in do_kernel_power_off()
670 	 *       switched to the sys-off based APIs.  in do_kernel_power_off()
683  *	kernel_can_power_off - check whether system can be powered off
685  *	Returns true if power-off handler is registered and system can be
696  *	kernel_power_off - power_off the system
716  * Reboot system call: for obvious reasons only root may call it,
718  * so that some mistake won't make this reboot the whole machine.
719  * You can also set the meaning of the ctrl-alt-del-key here.
721  * reboot doesn't sync: do that yourself before calling this.
723 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,  in SYSCALL_DEFINE4()  argument
731 	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))  in SYSCALL_DEFINE4()
732 		return -EPERM;  in SYSCALL_DEFINE4()
740 		return -EINVAL;  in SYSCALL_DEFINE4()
783 		ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);  in SYSCALL_DEFINE4()
785 			ret = -EFAULT;  in SYSCALL_DEFINE4()
788 		buffer[sizeof(buffer) - 1] = '\0';  in SYSCALL_DEFINE4()
806 		ret = -EINVAL;  in SYSCALL_DEFINE4()
819  * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
821  * is whether to reboot at once, or just ignore the ctrl-alt-del.
835 static const char reboot_cmd[] = "/sbin/reboot";
851 		ret = -ENOMEM;  in run_cmd()
864 		pr_warn("Failed to start orderly reboot: forcing the issue\n");  in __orderly_reboot()
903  * orderly_poweroff - Trigger an orderly system poweroff
925  * orderly_reboot - Trigger an orderly system reboot
927  * This may be called from any context to trigger a system reboot.
928  * If the orderly reboot fails, it will force an immediate reboot.
942 		return "reboot";  in hw_protection_action_str()
951  * hw_failure_emergency_action_func - emergency action work after a known delay
955  * a kernel poweroff or reboot after a configurable timeout value.
961 	pr_emerg("Hardware protection timed-out. Trying forced %s\n",  in hw_failure_emergency_action_func()
966 	 * expired. This means orderly_poweroff/reboot has not been able to  in hw_failure_emergency_action_func()
989  * hw_failure_emergency_schedule - Schedule an emergency system shutdown or reboot
995  * or reboot after a given period of time.
1009  * __hw_protection_shutdown - Trigger an emergency system shutdown or reboot
1011  * @reason:		Reason of emergency shutdown or reboot to be printed.
1012  * @ms_until_forced:	Time to wait for orderly shutdown or reboot before
1014  *			shutdown or reboot.
1017  * Initiate an emergency system shutdown or reboot in order to protect
1019  * NOTE: The request is ignored if protection shutdown or reboot is already
1021  * shutdown/reboot.
1049 		enum reboot_mode *mode;  in reboot_setup()  local
1053 		 * reboot= will cause us to disable DMI checking  in reboot_setup()
1059 			mode = &panic_reboot_mode;  in reboot_setup()
1062 			mode = &reboot_mode;  in reboot_setup()
1067 			*mode = REBOOT_WARM;  in reboot_setup()
1071 			*mode = REBOOT_COLD;  in reboot_setup()
1075 			*mode = REBOOT_HARD;  in reboot_setup()
1089 					pr_err("Ignoring the CPU number in reboot= option. "  in reboot_setup()
1096 				*mode = REBOOT_SOFT;  in reboot_setup()
1100 			*mode = REBOOT_GPIO;  in reboot_setup()
1125 __setup("reboot=", reboot_setup);
1173 		return -EPERM;  in mode_store()
1186 		return -EINVAL;  in mode_store()
1192 static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
1205 		return -EPERM;  in force_store()
1208 		return -EINVAL;  in force_store()
1250 		return -EPERM;  in type_store()
1265 		return -EINVAL;  in type_store()
1286 		return -EPERM;  in cpu_store()
1294 		return -ERANGE;  in cpu_store()
1322 		.mode           = 0644,
1326 		.procname       = "ctrl-alt-del",
1329 		.mode           = 0644,
1351 	reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);  in reboot_ksysfs_init()
1353 		return -ENOMEM;  in reboot_ksysfs_init()