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
40  * reboot_type is still set to its default value (i.e., reboot= hasn't
42  * suppress DMI scanning for reboot quirks.  Without it, it's
43  * impossible to override a faulty reboot quirk without recompiling.
58  *	emergency_restart - reboot the system
61  *	reboot the system.  This is called when we know we are in
62  *	trouble so this is our best effort to reboot.  This is
81  *	register_reboot_notifier - Register function to be called at reboot time
85  *	to be called at reboot time.
97  *	unregister_reboot_notifier - Unregister previously registered reboot notifier
100  *	Unregisters a previously registered reboot
103  *	Returns zero on success, or %-ENOENT on failure.
124 		return -ENOMEM;  in devm_register_reboot_notifier()
145  *	register_restart_handler - Register function to be called to reset
148  *	@nb->priority:	Handler priority. Handlers should follow the
164  *	machine_restart function calls do_kernel_restart - see below
170  *	Restart handlers are expected to be registered from non-architecture
189  *	unregister_restart_handler - Unregister previously registered
195  *	Returns zero on success, or %-ENOENT on failure.
204  *	do_kernel_restart - Execute kernel restart handler call chain
226 	/* Make certain the cpu I'm about to reboot on is online */  in migrate_to_reboot_cpu()
231 	current->flags |= PF_NO_SETAFFINITY;  in migrate_to_reboot_cpu()
238  *	kernel_restart - reboot the system
242  *	Shutdown everything and perform a clean reboot.
268  *	kernel_halt - halt the system
284  *	kernel_power_off - power_off the system
304  * Reboot system call: for obvious reasons only root may call it,
306  * so that some mistake won't make this reboot the whole machine.
307  * You can also set the meaning of the ctrl-alt-del-key here.
309  * reboot doesn't sync: do that yourself before calling this.
311 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,  in SYSCALL_DEFINE4()  argument
319 	if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))  in SYSCALL_DEFINE4()
320 		return -EPERM;  in SYSCALL_DEFINE4()
328 		return -EINVAL;  in SYSCALL_DEFINE4()
370 		ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);  in SYSCALL_DEFINE4()
372 			ret = -EFAULT;  in SYSCALL_DEFINE4()
375 		buffer[sizeof(buffer) - 1] = '\0';  in SYSCALL_DEFINE4()
393 		ret = -EINVAL;  in SYSCALL_DEFINE4()
406  * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
408  * is whether to reboot at once, or just ignore the ctrl-alt-del.
421 static const char reboot_cmd[] = "/sbin/reboot";
437 		ret = -ENOMEM;  in run_cmd()
450 		pr_warn("Failed to start orderly reboot: forcing the issue\n");  in __orderly_reboot()
489  * orderly_poweroff - Trigger an orderly system poweroff
511  * orderly_reboot - Trigger an orderly system reboot
513  * This may be called from any context to trigger a system reboot.
514  * If the orderly reboot fails, it will force an immediate reboot.
523  * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay
539 	pr_emerg("Hardware protection timed-out. Trying forced poweroff\n");  in hw_failure_emergency_poweroff_func()
553  * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
567  * hw_protection_shutdown - Trigger an emergency system poweroff
603 		enum reboot_mode *mode;  in reboot_setup()  local
607 		 * reboot= will cause us to disable DMI checking  in reboot_setup()
613 			mode = &panic_reboot_mode;  in reboot_setup()
616 			mode = &reboot_mode;  in reboot_setup()
621 			*mode = REBOOT_WARM;  in reboot_setup()
625 			*mode = REBOOT_COLD;  in reboot_setup()
629 			*mode = REBOOT_HARD;  in reboot_setup()
643 					pr_err("Ignoring the CPU number in reboot= option. "  in reboot_setup()
650 				*mode = REBOOT_SOFT;  in reboot_setup()
654 			*mode = REBOOT_GPIO;  in reboot_setup()
679 __setup("reboot=", reboot_setup);
727 		return -EPERM;  in mode_store()
740 		return -EINVAL;  in mode_store()
746 static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
759 		return -EPERM;  in force_store()
762 		return -EINVAL;  in force_store()
804 		return -EPERM;  in type_store()
819 		return -EINVAL;  in type_store()
840 		return -EPERM;  in cpu_store()
848 		return -ERANGE;  in cpu_store()
879 	reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);  in reboot_ksysfs_init()
881 		return -ENOMEM;  in reboot_ksysfs_init()