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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/reboot.c
4 *
5 * Copyright (C) 2013 Linus Torvalds
6 */
7
8#define pr_fmt(fmt) "reboot: " fmt
9
10#include <linux/atomic.h>
11#include <linux/ctype.h>
12#include <linux/export.h>
13#include <linux/kexec.h>
14#include <linux/kmod.h>
15#include <linux/kmsg_dump.h>
16#include <linux/reboot.h>
17#include <linux/suspend.h>
18#include <linux/syscalls.h>
19#include <linux/syscore_ops.h>
20#include <linux/uaccess.h>
21
22/*
23 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
24 */
25
26static int C_A_D = 1;
27struct pid *cad_pid;
28EXPORT_SYMBOL(cad_pid);
29
30#if defined(CONFIG_ARM)
31#define DEFAULT_REBOOT_MODE = REBOOT_HARD
32#else
33#define DEFAULT_REBOOT_MODE
34#endif
35enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
36EXPORT_SYMBOL_GPL(reboot_mode);
37enum reboot_mode panic_reboot_mode = REBOOT_UNDEFINED;
38
39/*
40 * This variable is used privately to keep track of whether or not
41 * reboot_type is still set to its default value (i.e., reboot= hasn't
42 * been set on the command line). This is needed so that we can
43 * suppress DMI scanning for reboot quirks. Without it, it's
44 * impossible to override a faulty reboot quirk without recompiling.
45 */
46int reboot_default = 1;
47int reboot_cpu;
48enum reboot_type reboot_type = BOOT_ACPI;
49int reboot_force;
50
51struct sys_off_handler {
52 struct notifier_block nb;
53 int (*sys_off_cb)(struct sys_off_data *data);
54 void *cb_data;
55 enum sys_off_mode mode;
56 bool blocking;
57 void *list;
58};
59
60/*
61 * Temporary stub that prevents linkage failure while we're in process
62 * of removing all uses of legacy pm_power_off() around the kernel.
63 */
64void __weak (*pm_power_off)(void);
65
66/**
67 * emergency_restart - reboot the system
68 *
69 * Without shutting down any hardware or taking any locks
70 * reboot the system. This is called when we know we are in
71 * trouble so this is our best effort to reboot. This is
72 * safe to call in interrupt context.
73 */
74void emergency_restart(void)
75{
76 kmsg_dump(KMSG_DUMP_EMERG);
77 machine_emergency_restart();
78}
79EXPORT_SYMBOL_GPL(emergency_restart);
80
81void kernel_restart_prepare(char *cmd)
82{
83 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
84 system_state = SYSTEM_RESTART;
85 usermodehelper_disable();
86 device_shutdown();
87}
88
89/**
90 * register_reboot_notifier - Register function to be called at reboot time
91 * @nb: Info about notifier function to be called
92 *
93 * Registers a function with the list of functions
94 * to be called at reboot time.
95 *
96 * Currently always returns zero, as blocking_notifier_chain_register()
97 * always returns zero.
98 */
99int register_reboot_notifier(struct notifier_block *nb)
100{
101 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
102}
103EXPORT_SYMBOL(register_reboot_notifier);
104
105/**
106 * unregister_reboot_notifier - Unregister previously registered reboot notifier
107 * @nb: Hook to be unregistered
108 *
109 * Unregisters a previously registered reboot
110 * notifier function.
111 *
112 * Returns zero on success, or %-ENOENT on failure.
113 */
114int unregister_reboot_notifier(struct notifier_block *nb)
115{
116 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
117}
118EXPORT_SYMBOL(unregister_reboot_notifier);
119
120static void devm_unregister_reboot_notifier(struct device *dev, void *res)
121{
122 WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
123}
124
125int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
126{
127 struct notifier_block **rcnb;
128 int ret;
129
130 rcnb = devres_alloc(devm_unregister_reboot_notifier,
131 sizeof(*rcnb), GFP_KERNEL);
132 if (!rcnb)
133 return -ENOMEM;
134
135 ret = register_reboot_notifier(nb);
136 if (!ret) {
137 *rcnb = nb;
138 devres_add(dev, rcnb);
139 } else {
140 devres_free(rcnb);
141 }
142
143 return ret;
144}
145EXPORT_SYMBOL(devm_register_reboot_notifier);
146
147/*
148 * Notifier list for kernel code which wants to be called
149 * to restart the system.
150 */
151static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
152
153/**
154 * register_restart_handler - Register function to be called to reset
155 * the system
156 * @nb: Info about handler function to be called
157 * @nb->priority: Handler priority. Handlers should follow the
158 * following guidelines for setting priorities.
159 * 0: Restart handler of last resort,
160 * with limited restart capabilities
161 * 128: Default restart handler; use if no other
162 * restart handler is expected to be available,
163 * and/or if restart functionality is
164 * sufficient to restart the entire system
165 * 255: Highest priority restart handler, will
166 * preempt all other restart handlers
167 *
168 * Registers a function with code to be called to restart the
169 * system.
170 *
171 * Registered functions will be called from machine_restart as last
172 * step of the restart sequence (if the architecture specific
173 * machine_restart function calls do_kernel_restart - see below
174 * for details).
175 * Registered functions are expected to restart the system immediately.
176 * If more than one function is registered, the restart handler priority
177 * selects which function will be called first.
178 *
179 * Restart handlers are expected to be registered from non-architecture
180 * code, typically from drivers. A typical use case would be a system
181 * where restart functionality is provided through a watchdog. Multiple
182 * restart handlers may exist; for example, one restart handler might
183 * restart the entire system, while another only restarts the CPU.
184 * In such cases, the restart handler which only restarts part of the
185 * hardware is expected to register with low priority to ensure that
186 * it only runs if no other means to restart the system is available.
187 *
188 * Currently always returns zero, as atomic_notifier_chain_register()
189 * always returns zero.
190 */
191int register_restart_handler(struct notifier_block *nb)
192{
193 return atomic_notifier_chain_register(&restart_handler_list, nb);
194}
195EXPORT_SYMBOL(register_restart_handler);
196
197/**
198 * unregister_restart_handler - Unregister previously registered
199 * restart handler
200 * @nb: Hook to be unregistered
201 *
202 * Unregisters a previously registered restart handler function.
203 *
204 * Returns zero on success, or %-ENOENT on failure.
205 */
206int unregister_restart_handler(struct notifier_block *nb)
207{
208 return atomic_notifier_chain_unregister(&restart_handler_list, nb);
209}
210EXPORT_SYMBOL(unregister_restart_handler);
211
212/**
213 * do_kernel_restart - Execute kernel restart handler call chain
214 *
215 * Calls functions registered with register_restart_handler.
216 *
217 * Expected to be called from machine_restart as last step of the restart
218 * sequence.
219 *
220 * Restarts the system immediately if a restart handler function has been
221 * registered. Otherwise does nothing.
222 */
223void do_kernel_restart(char *cmd)
224{
225 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
226}
227
228void migrate_to_reboot_cpu(void)
229{
230 /* The boot cpu is always logical cpu 0 */
231 int cpu = reboot_cpu;
232
233 cpu_hotplug_disable();
234
235 /* Make certain the cpu I'm about to reboot on is online */
236 if (!cpu_online(cpu))
237 cpu = cpumask_first(cpu_online_mask);
238
239 /* Prevent races with other tasks migrating this task */
240 current->flags |= PF_NO_SETAFFINITY;
241
242 /* Make certain I only run on the appropriate processor */
243 set_cpus_allowed_ptr(current, cpumask_of(cpu));
244}
245
246/*
247 * Notifier list for kernel code which wants to be called
248 * to prepare system for restart.
249 */
250static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list);
251
252static void do_kernel_restart_prepare(void)
253{
254 blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL);
255}
256
257/**
258 * kernel_restart - reboot the system
259 * @cmd: pointer to buffer containing command to execute for restart
260 * or %NULL
261 *
262 * Shutdown everything and perform a clean reboot.
263 * This is not safe to call in interrupt context.
264 */
265void kernel_restart(char *cmd)
266{
267 kernel_restart_prepare(cmd);
268 do_kernel_restart_prepare();
269 migrate_to_reboot_cpu();
270 syscore_shutdown();
271 if (!cmd)
272 pr_emerg("Restarting system\n");
273 else
274 pr_emerg("Restarting system with command '%s'\n", cmd);
275 kmsg_dump(KMSG_DUMP_SHUTDOWN);
276 machine_restart(cmd);
277}
278EXPORT_SYMBOL_GPL(kernel_restart);
279
280static void kernel_shutdown_prepare(enum system_states state)
281{
282 blocking_notifier_call_chain(&reboot_notifier_list,
283 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
284 system_state = state;
285 usermodehelper_disable();
286 device_shutdown();
287}
288/**
289 * kernel_halt - halt the system
290 *
291 * Shutdown everything and perform a clean system halt.
292 */
293void kernel_halt(void)
294{
295 kernel_shutdown_prepare(SYSTEM_HALT);
296 migrate_to_reboot_cpu();
297 syscore_shutdown();
298 pr_emerg("System halted\n");
299 kmsg_dump(KMSG_DUMP_SHUTDOWN);
300 machine_halt();
301}
302EXPORT_SYMBOL_GPL(kernel_halt);
303
304/*
305 * Notifier list for kernel code which wants to be called
306 * to prepare system for power off.
307 */
308static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list);
309
310/*
311 * Notifier list for kernel code which wants to be called
312 * to power off system.
313 */
314static ATOMIC_NOTIFIER_HEAD(power_off_handler_list);
315
316static int sys_off_notify(struct notifier_block *nb,
317 unsigned long mode, void *cmd)
318{
319 struct sys_off_handler *handler;
320 struct sys_off_data data = {};
321
322 handler = container_of(nb, struct sys_off_handler, nb);
323 data.cb_data = handler->cb_data;
324 data.mode = mode;
325 data.cmd = cmd;
326
327 return handler->sys_off_cb(&data);
328}
329
330static struct sys_off_handler platform_sys_off_handler;
331
332static struct sys_off_handler *alloc_sys_off_handler(int priority)
333{
334 struct sys_off_handler *handler;
335 gfp_t flags;
336
337 /*
338 * Platforms like m68k can't allocate sys_off handler dynamically
339 * at the early boot time because memory allocator isn't available yet.
340 */
341 if (priority == SYS_OFF_PRIO_PLATFORM) {
342 handler = &platform_sys_off_handler;
343 if (handler->cb_data)
344 return ERR_PTR(-EBUSY);
345 } else {
346 if (system_state > SYSTEM_RUNNING)
347 flags = GFP_ATOMIC;
348 else
349 flags = GFP_KERNEL;
350
351 handler = kzalloc(sizeof(*handler), flags);
352 if (!handler)
353 return ERR_PTR(-ENOMEM);
354 }
355
356 return handler;
357}
358
359static void free_sys_off_handler(struct sys_off_handler *handler)
360{
361 if (handler == &platform_sys_off_handler)
362 memset(handler, 0, sizeof(*handler));
363 else
364 kfree(handler);
365}
366
367/**
368 * register_sys_off_handler - Register sys-off handler
369 * @mode: Sys-off mode
370 * @priority: Handler priority
371 * @callback: Callback function
372 * @cb_data: Callback argument
373 *
374 * Registers system power-off or restart handler that will be invoked
375 * at the step corresponding to the given sys-off mode. Handler's callback
376 * should return NOTIFY_DONE to permit execution of the next handler in
377 * the call chain or NOTIFY_STOP to break the chain (in error case for
378 * example).
379 *
380 * Multiple handlers can be registered at the default priority level.
381 *
382 * Only one handler can be registered at the non-default priority level,
383 * otherwise ERR_PTR(-EBUSY) is returned.
384 *
385 * Returns a new instance of struct sys_off_handler on success, or
386 * an ERR_PTR()-encoded error code otherwise.
387 */
388struct sys_off_handler *
389register_sys_off_handler(enum sys_off_mode mode,
390 int priority,
391 int (*callback)(struct sys_off_data *data),
392 void *cb_data)
393{
394 struct sys_off_handler *handler;
395 int err;
396
397 handler = alloc_sys_off_handler(priority);
398 if (IS_ERR(handler))
399 return handler;
400
401 switch (mode) {
402 case SYS_OFF_MODE_POWER_OFF_PREPARE:
403 handler->list = &power_off_prep_handler_list;
404 handler->blocking = true;
405 break;
406
407 case SYS_OFF_MODE_POWER_OFF:
408 handler->list = &power_off_handler_list;
409 break;
410
411 case SYS_OFF_MODE_RESTART_PREPARE:
412 handler->list = &restart_prep_handler_list;
413 handler->blocking = true;
414 break;
415
416 case SYS_OFF_MODE_RESTART:
417 handler->list = &restart_handler_list;
418 break;
419
420 default:
421 free_sys_off_handler(handler);
422 return ERR_PTR(-EINVAL);
423 }
424
425 handler->nb.notifier_call = sys_off_notify;
426 handler->nb.priority = priority;
427 handler->sys_off_cb = callback;
428 handler->cb_data = cb_data;
429 handler->mode = mode;
430
431 if (handler->blocking) {
432 if (priority == SYS_OFF_PRIO_DEFAULT)
433 err = blocking_notifier_chain_register(handler->list,
434 &handler->nb);
435 else
436 err = blocking_notifier_chain_register_unique_prio(handler->list,
437 &handler->nb);
438 } else {
439 if (priority == SYS_OFF_PRIO_DEFAULT)
440 err = atomic_notifier_chain_register(handler->list,
441 &handler->nb);
442 else
443 err = atomic_notifier_chain_register_unique_prio(handler->list,
444 &handler->nb);
445 }
446
447 if (err) {
448 free_sys_off_handler(handler);
449 return ERR_PTR(err);
450 }
451
452 return handler;
453}
454EXPORT_SYMBOL_GPL(register_sys_off_handler);
455
456/**
457 * unregister_sys_off_handler - Unregister sys-off handler
458 * @handler: Sys-off handler
459 *
460 * Unregisters given sys-off handler.
461 */
462void unregister_sys_off_handler(struct sys_off_handler *handler)
463{
464 int err;
465
466 if (IS_ERR_OR_NULL(handler))
467 return;
468
469 if (handler->blocking)
470 err = blocking_notifier_chain_unregister(handler->list,
471 &handler->nb);
472 else
473 err = atomic_notifier_chain_unregister(handler->list,
474 &handler->nb);
475
476 /* sanity check, shall never happen */
477 WARN_ON(err);
478
479 free_sys_off_handler(handler);
480}
481EXPORT_SYMBOL_GPL(unregister_sys_off_handler);
482
483static void devm_unregister_sys_off_handler(void *data)
484{
485 struct sys_off_handler *handler = data;
486
487 unregister_sys_off_handler(handler);
488}
489
490/**
491 * devm_register_sys_off_handler - Register sys-off handler
492 * @dev: Device that registers handler
493 * @mode: Sys-off mode
494 * @priority: Handler priority
495 * @callback: Callback function
496 * @cb_data: Callback argument
497 *
498 * Registers resource-managed sys-off handler.
499 *
500 * Returns zero on success, or error code on failure.
501 */
502int devm_register_sys_off_handler(struct device *dev,
503 enum sys_off_mode mode,
504 int priority,
505 int (*callback)(struct sys_off_data *data),
506 void *cb_data)
507{
508 struct sys_off_handler *handler;
509
510 handler = register_sys_off_handler(mode, priority, callback, cb_data);
511 if (IS_ERR(handler))
512 return PTR_ERR(handler);
513
514 return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler,
515 handler);
516}
517EXPORT_SYMBOL_GPL(devm_register_sys_off_handler);
518
519/**
520 * devm_register_power_off_handler - Register power-off handler
521 * @dev: Device that registers callback
522 * @callback: Callback function
523 * @cb_data: Callback's argument
524 *
525 * Registers resource-managed sys-off handler with a default priority
526 * and using power-off mode.
527 *
528 * Returns zero on success, or error code on failure.
529 */
530int devm_register_power_off_handler(struct device *dev,
531 int (*callback)(struct sys_off_data *data),
532 void *cb_data)
533{
534 return devm_register_sys_off_handler(dev,
535 SYS_OFF_MODE_POWER_OFF,
536 SYS_OFF_PRIO_DEFAULT,
537 callback, cb_data);
538}
539EXPORT_SYMBOL_GPL(devm_register_power_off_handler);
540
541/**
542 * devm_register_restart_handler - Register restart handler
543 * @dev: Device that registers callback
544 * @callback: Callback function
545 * @cb_data: Callback's argument
546 *
547 * Registers resource-managed sys-off handler with a default priority
548 * and using restart mode.
549 *
550 * Returns zero on success, or error code on failure.
551 */
552int devm_register_restart_handler(struct device *dev,
553 int (*callback)(struct sys_off_data *data),
554 void *cb_data)
555{
556 return devm_register_sys_off_handler(dev,
557 SYS_OFF_MODE_RESTART,
558 SYS_OFF_PRIO_DEFAULT,
559 callback, cb_data);
560}
561EXPORT_SYMBOL_GPL(devm_register_restart_handler);
562
563static struct sys_off_handler *platform_power_off_handler;
564
565static int platform_power_off_notify(struct sys_off_data *data)
566{
567 void (*platform_power_power_off_cb)(void) = data->cb_data;
568
569 platform_power_power_off_cb();
570
571 return NOTIFY_DONE;
572}
573
574/**
575 * register_platform_power_off - Register platform-level power-off callback
576 * @power_off: Power-off callback
577 *
578 * Registers power-off callback that will be called as last step
579 * of the power-off sequence. This callback is expected to be invoked
580 * for the last resort. Only one platform power-off callback is allowed
581 * to be registered at a time.
582 *
583 * Returns zero on success, or error code on failure.
584 */
585int register_platform_power_off(void (*power_off)(void))
586{
587 struct sys_off_handler *handler;
588
589 handler = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
590 SYS_OFF_PRIO_PLATFORM,
591 platform_power_off_notify,
592 power_off);
593 if (IS_ERR(handler))
594 return PTR_ERR(handler);
595
596 platform_power_off_handler = handler;
597
598 return 0;
599}
600EXPORT_SYMBOL_GPL(register_platform_power_off);
601
602/**
603 * unregister_platform_power_off - Unregister platform-level power-off callback
604 * @power_off: Power-off callback
605 *
606 * Unregisters previously registered platform power-off callback.
607 */
608void unregister_platform_power_off(void (*power_off)(void))
609{
610 if (platform_power_off_handler &&
611 platform_power_off_handler->cb_data == power_off) {
612 unregister_sys_off_handler(platform_power_off_handler);
613 platform_power_off_handler = NULL;
614 }
615}
616EXPORT_SYMBOL_GPL(unregister_platform_power_off);
617
618static int legacy_pm_power_off(struct sys_off_data *data)
619{
620 if (pm_power_off)
621 pm_power_off();
622
623 return NOTIFY_DONE;
624}
625
626static void do_kernel_power_off_prepare(void)
627{
628 blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL);
629}
630
631/**
632 * do_kernel_power_off - Execute kernel power-off handler call chain
633 *
634 * Expected to be called as last step of the power-off sequence.
635 *
636 * Powers off the system immediately if a power-off handler function has
637 * been registered. Otherwise does nothing.
638 */
639void do_kernel_power_off(void)
640{
641 struct sys_off_handler *sys_off = NULL;
642
643 /*
644 * Register sys-off handlers for legacy PM callback. This allows
645 * legacy PM callbacks temporary co-exist with the new sys-off API.
646 *
647 * TODO: Remove legacy handlers once all legacy PM users will be
648 * switched to the sys-off based APIs.
649 */
650 if (pm_power_off)
651 sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
652 SYS_OFF_PRIO_DEFAULT,
653 legacy_pm_power_off, NULL);
654
655 atomic_notifier_call_chain(&power_off_handler_list, 0, NULL);
656
657 unregister_sys_off_handler(sys_off);
658}
659
660/**
661 * kernel_can_power_off - check whether system can be powered off
662 *
663 * Returns true if power-off handler is registered and system can be
664 * powered off, false otherwise.
665 */
666bool kernel_can_power_off(void)
667{
668 return !atomic_notifier_call_chain_is_empty(&power_off_handler_list) ||
669 pm_power_off;
670}
671EXPORT_SYMBOL_GPL(kernel_can_power_off);
672
673/**
674 * kernel_power_off - power_off the system
675 *
676 * Shutdown everything and perform a clean system power_off.
677 */
678void kernel_power_off(void)
679{
680 kernel_shutdown_prepare(SYSTEM_POWER_OFF);
681 do_kernel_power_off_prepare();
682 migrate_to_reboot_cpu();
683 syscore_shutdown();
684 pr_emerg("Power down\n");
685 kmsg_dump(KMSG_DUMP_SHUTDOWN);
686 machine_power_off();
687}
688EXPORT_SYMBOL_GPL(kernel_power_off);
689
690DEFINE_MUTEX(system_transition_mutex);
691
692/*
693 * Reboot system call: for obvious reasons only root may call it,
694 * and even root needs to set up some magic numbers in the registers
695 * so that some mistake won't make this reboot the whole machine.
696 * You can also set the meaning of the ctrl-alt-del-key here.
697 *
698 * reboot doesn't sync: do that yourself before calling this.
699 */
700SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
701 void __user *, arg)
702{
703 struct pid_namespace *pid_ns = task_active_pid_ns(current);
704 char buffer[256];
705 int ret = 0;
706
707 /* We only trust the superuser with rebooting the system. */
708 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
709 return -EPERM;
710
711 /* For safety, we require "magic" arguments. */
712 if (magic1 != LINUX_REBOOT_MAGIC1 ||
713 (magic2 != LINUX_REBOOT_MAGIC2 &&
714 magic2 != LINUX_REBOOT_MAGIC2A &&
715 magic2 != LINUX_REBOOT_MAGIC2B &&
716 magic2 != LINUX_REBOOT_MAGIC2C))
717 return -EINVAL;
718
719 /*
720 * If pid namespaces are enabled and the current task is in a child
721 * pid_namespace, the command is handled by reboot_pid_ns() which will
722 * call do_exit().
723 */
724 ret = reboot_pid_ns(pid_ns, cmd);
725 if (ret)
726 return ret;
727
728 /* Instead of trying to make the power_off code look like
729 * halt when pm_power_off is not set do it the easy way.
730 */
731 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off())
732 cmd = LINUX_REBOOT_CMD_HALT;
733
734 mutex_lock(&system_transition_mutex);
735 switch (cmd) {
736 case LINUX_REBOOT_CMD_RESTART:
737 kernel_restart(NULL);
738 break;
739
740 case LINUX_REBOOT_CMD_CAD_ON:
741 C_A_D = 1;
742 break;
743
744 case LINUX_REBOOT_CMD_CAD_OFF:
745 C_A_D = 0;
746 break;
747
748 case LINUX_REBOOT_CMD_HALT:
749 kernel_halt();
750 do_exit(0);
751
752 case LINUX_REBOOT_CMD_POWER_OFF:
753 kernel_power_off();
754 do_exit(0);
755 break;
756
757 case LINUX_REBOOT_CMD_RESTART2:
758 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
759 if (ret < 0) {
760 ret = -EFAULT;
761 break;
762 }
763 buffer[sizeof(buffer) - 1] = '\0';
764
765 kernel_restart(buffer);
766 break;
767
768#ifdef CONFIG_KEXEC_CORE
769 case LINUX_REBOOT_CMD_KEXEC:
770 ret = kernel_kexec();
771 break;
772#endif
773
774#ifdef CONFIG_HIBERNATION
775 case LINUX_REBOOT_CMD_SW_SUSPEND:
776 ret = hibernate();
777 break;
778#endif
779
780 default:
781 ret = -EINVAL;
782 break;
783 }
784 mutex_unlock(&system_transition_mutex);
785 return ret;
786}
787
788static void deferred_cad(struct work_struct *dummy)
789{
790 kernel_restart(NULL);
791}
792
793/*
794 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
795 * As it's called within an interrupt, it may NOT sync: the only choice
796 * is whether to reboot at once, or just ignore the ctrl-alt-del.
797 */
798void ctrl_alt_del(void)
799{
800 static DECLARE_WORK(cad_work, deferred_cad);
801
802 if (C_A_D)
803 schedule_work(&cad_work);
804 else
805 kill_cad_pid(SIGINT, 1);
806}
807
808#define POWEROFF_CMD_PATH_LEN 256
809static char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
810static const char reboot_cmd[] = "/sbin/reboot";
811
812static int run_cmd(const char *cmd)
813{
814 char **argv;
815 static char *envp[] = {
816 "HOME=/",
817 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
818 NULL
819 };
820 int ret;
821 argv = argv_split(GFP_KERNEL, cmd, NULL);
822 if (argv) {
823 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
824 argv_free(argv);
825 } else {
826 ret = -ENOMEM;
827 }
828
829 return ret;
830}
831
832static int __orderly_reboot(void)
833{
834 int ret;
835
836 ret = run_cmd(reboot_cmd);
837
838 if (ret) {
839 pr_warn("Failed to start orderly reboot: forcing the issue\n");
840 emergency_sync();
841 kernel_restart(NULL);
842 }
843
844 return ret;
845}
846
847static int __orderly_poweroff(bool force)
848{
849 int ret;
850
851 ret = run_cmd(poweroff_cmd);
852
853 if (ret && force) {
854 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
855
856 /*
857 * I guess this should try to kick off some daemon to sync and
858 * poweroff asap. Or not even bother syncing if we're doing an
859 * emergency shutdown?
860 */
861 emergency_sync();
862 kernel_power_off();
863 }
864
865 return ret;
866}
867
868static bool poweroff_force;
869
870static void poweroff_work_func(struct work_struct *work)
871{
872 __orderly_poweroff(poweroff_force);
873}
874
875static DECLARE_WORK(poweroff_work, poweroff_work_func);
876
877/**
878 * orderly_poweroff - Trigger an orderly system poweroff
879 * @force: force poweroff if command execution fails
880 *
881 * This may be called from any context to trigger a system shutdown.
882 * If the orderly shutdown fails, it will force an immediate shutdown.
883 */
884void orderly_poweroff(bool force)
885{
886 if (force) /* do not override the pending "true" */
887 poweroff_force = true;
888 schedule_work(&poweroff_work);
889}
890EXPORT_SYMBOL_GPL(orderly_poweroff);
891
892static void reboot_work_func(struct work_struct *work)
893{
894 __orderly_reboot();
895}
896
897static DECLARE_WORK(reboot_work, reboot_work_func);
898
899/**
900 * orderly_reboot - Trigger an orderly system reboot
901 *
902 * This may be called from any context to trigger a system reboot.
903 * If the orderly reboot fails, it will force an immediate reboot.
904 */
905void orderly_reboot(void)
906{
907 schedule_work(&reboot_work);
908}
909EXPORT_SYMBOL_GPL(orderly_reboot);
910
911/**
912 * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay
913 * @work: work_struct associated with the emergency poweroff function
914 *
915 * This function is called in very critical situations to force
916 * a kernel poweroff after a configurable timeout value.
917 */
918static void hw_failure_emergency_poweroff_func(struct work_struct *work)
919{
920 /*
921 * We have reached here after the emergency shutdown waiting period has
922 * expired. This means orderly_poweroff has not been able to shut off
923 * the system for some reason.
924 *
925 * Try to shut down the system immediately using kernel_power_off
926 * if populated
927 */
928 pr_emerg("Hardware protection timed-out. Trying forced poweroff\n");
929 kernel_power_off();
930
931 /*
932 * Worst of the worst case trigger emergency restart
933 */
934 pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n");
935 emergency_restart();
936}
937
938static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
939 hw_failure_emergency_poweroff_func);
940
941/**
942 * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
943 *
944 * This may be called from any critical situation to trigger a system shutdown
945 * after a given period of time. If time is negative this is not scheduled.
946 */
947static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
948{
949 if (poweroff_delay_ms <= 0)
950 return;
951 schedule_delayed_work(&hw_failure_emergency_poweroff_work,
952 msecs_to_jiffies(poweroff_delay_ms));
953}
954
955/**
956 * hw_protection_shutdown - Trigger an emergency system poweroff
957 *
958 * @reason: Reason of emergency shutdown to be printed.
959 * @ms_until_forced: Time to wait for orderly shutdown before tiggering a
960 * forced shudown. Negative value disables the forced
961 * shutdown.
962 *
963 * Initiate an emergency system shutdown in order to protect hardware from
964 * further damage. Usage examples include a thermal protection or a voltage or
965 * current regulator failures.
966 * NOTE: The request is ignored if protection shutdown is already pending even
967 * if the previous request has given a large timeout for forced shutdown.
968 * Can be called from any context.
969 */
970void hw_protection_shutdown(const char *reason, int ms_until_forced)
971{
972 static atomic_t allow_proceed = ATOMIC_INIT(1);
973
974 pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
975
976 /* Shutdown should be initiated only once. */
977 if (!atomic_dec_and_test(&allow_proceed))
978 return;
979
980 /*
981 * Queue a backup emergency shutdown in the event of
982 * orderly_poweroff failure
983 */
984 hw_failure_emergency_poweroff(ms_until_forced);
985 orderly_poweroff(true);
986}
987EXPORT_SYMBOL_GPL(hw_protection_shutdown);
988
989static int __init reboot_setup(char *str)
990{
991 for (;;) {
992 enum reboot_mode *mode;
993
994 /*
995 * Having anything passed on the command line via
996 * reboot= will cause us to disable DMI checking
997 * below.
998 */
999 reboot_default = 0;
1000
1001 if (!strncmp(str, "panic_", 6)) {
1002 mode = &panic_reboot_mode;
1003 str += 6;
1004 } else {
1005 mode = &reboot_mode;
1006 }
1007
1008 switch (*str) {
1009 case 'w':
1010 *mode = REBOOT_WARM;
1011 break;
1012
1013 case 'c':
1014 *mode = REBOOT_COLD;
1015 break;
1016
1017 case 'h':
1018 *mode = REBOOT_HARD;
1019 break;
1020
1021 case 's':
1022 /*
1023 * reboot_cpu is s[mp]#### with #### being the processor
1024 * to be used for rebooting. Skip 's' or 'smp' prefix.
1025 */
1026 str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
1027
1028 if (isdigit(str[0])) {
1029 int cpu = simple_strtoul(str, NULL, 0);
1030
1031 if (cpu >= num_possible_cpus()) {
1032 pr_err("Ignoring the CPU number in reboot= option. "
1033 "CPU %d exceeds possible cpu number %d\n",
1034 cpu, num_possible_cpus());
1035 break;
1036 }
1037 reboot_cpu = cpu;
1038 } else
1039 *mode = REBOOT_SOFT;
1040 break;
1041
1042 case 'g':
1043 *mode = REBOOT_GPIO;
1044 break;
1045
1046 case 'b':
1047 case 'a':
1048 case 'k':
1049 case 't':
1050 case 'e':
1051 case 'p':
1052 reboot_type = *str;
1053 break;
1054
1055 case 'f':
1056 reboot_force = 1;
1057 break;
1058 }
1059
1060 str = strchr(str, ',');
1061 if (str)
1062 str++;
1063 else
1064 break;
1065 }
1066 return 1;
1067}
1068__setup("reboot=", reboot_setup);
1069
1070#ifdef CONFIG_SYSFS
1071
1072#define REBOOT_COLD_STR "cold"
1073#define REBOOT_WARM_STR "warm"
1074#define REBOOT_HARD_STR "hard"
1075#define REBOOT_SOFT_STR "soft"
1076#define REBOOT_GPIO_STR "gpio"
1077#define REBOOT_UNDEFINED_STR "undefined"
1078
1079#define BOOT_TRIPLE_STR "triple"
1080#define BOOT_KBD_STR "kbd"
1081#define BOOT_BIOS_STR "bios"
1082#define BOOT_ACPI_STR "acpi"
1083#define BOOT_EFI_STR "efi"
1084#define BOOT_PCI_STR "pci"
1085
1086static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1087{
1088 const char *val;
1089
1090 switch (reboot_mode) {
1091 case REBOOT_COLD:
1092 val = REBOOT_COLD_STR;
1093 break;
1094 case REBOOT_WARM:
1095 val = REBOOT_WARM_STR;
1096 break;
1097 case REBOOT_HARD:
1098 val = REBOOT_HARD_STR;
1099 break;
1100 case REBOOT_SOFT:
1101 val = REBOOT_SOFT_STR;
1102 break;
1103 case REBOOT_GPIO:
1104 val = REBOOT_GPIO_STR;
1105 break;
1106 default:
1107 val = REBOOT_UNDEFINED_STR;
1108 }
1109
1110 return sprintf(buf, "%s\n", val);
1111}
1112static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr,
1113 const char *buf, size_t count)
1114{
1115 if (!capable(CAP_SYS_BOOT))
1116 return -EPERM;
1117
1118 if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR)))
1119 reboot_mode = REBOOT_COLD;
1120 else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR)))
1121 reboot_mode = REBOOT_WARM;
1122 else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR)))
1123 reboot_mode = REBOOT_HARD;
1124 else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR)))
1125 reboot_mode = REBOOT_SOFT;
1126 else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR)))
1127 reboot_mode = REBOOT_GPIO;
1128 else
1129 return -EINVAL;
1130
1131 reboot_default = 0;
1132
1133 return count;
1134}
1135static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
1136
1137#ifdef CONFIG_X86
1138static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1139{
1140 return sprintf(buf, "%d\n", reboot_force);
1141}
1142static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
1143 const char *buf, size_t count)
1144{
1145 bool res;
1146
1147 if (!capable(CAP_SYS_BOOT))
1148 return -EPERM;
1149
1150 if (kstrtobool(buf, &res))
1151 return -EINVAL;
1152
1153 reboot_default = 0;
1154 reboot_force = res;
1155
1156 return count;
1157}
1158static struct kobj_attribute reboot_force_attr = __ATTR_RW(force);
1159
1160static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1161{
1162 const char *val;
1163
1164 switch (reboot_type) {
1165 case BOOT_TRIPLE:
1166 val = BOOT_TRIPLE_STR;
1167 break;
1168 case BOOT_KBD:
1169 val = BOOT_KBD_STR;
1170 break;
1171 case BOOT_BIOS:
1172 val = BOOT_BIOS_STR;
1173 break;
1174 case BOOT_ACPI:
1175 val = BOOT_ACPI_STR;
1176 break;
1177 case BOOT_EFI:
1178 val = BOOT_EFI_STR;
1179 break;
1180 case BOOT_CF9_FORCE:
1181 val = BOOT_PCI_STR;
1182 break;
1183 default:
1184 val = REBOOT_UNDEFINED_STR;
1185 }
1186
1187 return sprintf(buf, "%s\n", val);
1188}
1189static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr,
1190 const char *buf, size_t count)
1191{
1192 if (!capable(CAP_SYS_BOOT))
1193 return -EPERM;
1194
1195 if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR)))
1196 reboot_type = BOOT_TRIPLE;
1197 else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR)))
1198 reboot_type = BOOT_KBD;
1199 else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR)))
1200 reboot_type = BOOT_BIOS;
1201 else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR)))
1202 reboot_type = BOOT_ACPI;
1203 else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR)))
1204 reboot_type = BOOT_EFI;
1205 else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR)))
1206 reboot_type = BOOT_CF9_FORCE;
1207 else
1208 return -EINVAL;
1209
1210 reboot_default = 0;
1211
1212 return count;
1213}
1214static struct kobj_attribute reboot_type_attr = __ATTR_RW(type);
1215#endif
1216
1217#ifdef CONFIG_SMP
1218static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1219{
1220 return sprintf(buf, "%d\n", reboot_cpu);
1221}
1222static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr,
1223 const char *buf, size_t count)
1224{
1225 unsigned int cpunum;
1226 int rc;
1227
1228 if (!capable(CAP_SYS_BOOT))
1229 return -EPERM;
1230
1231 rc = kstrtouint(buf, 0, &cpunum);
1232
1233 if (rc)
1234 return rc;
1235
1236 if (cpunum >= num_possible_cpus())
1237 return -ERANGE;
1238
1239 reboot_default = 0;
1240 reboot_cpu = cpunum;
1241
1242 return count;
1243}
1244static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu);
1245#endif
1246
1247static struct attribute *reboot_attrs[] = {
1248 &reboot_mode_attr.attr,
1249#ifdef CONFIG_X86
1250 &reboot_force_attr.attr,
1251 &reboot_type_attr.attr,
1252#endif
1253#ifdef CONFIG_SMP
1254 &reboot_cpu_attr.attr,
1255#endif
1256 NULL,
1257};
1258
1259#ifdef CONFIG_SYSCTL
1260static struct ctl_table kern_reboot_table[] = {
1261 {
1262 .procname = "poweroff_cmd",
1263 .data = &poweroff_cmd,
1264 .maxlen = POWEROFF_CMD_PATH_LEN,
1265 .mode = 0644,
1266 .proc_handler = proc_dostring,
1267 },
1268 {
1269 .procname = "ctrl-alt-del",
1270 .data = &C_A_D,
1271 .maxlen = sizeof(int),
1272 .mode = 0644,
1273 .proc_handler = proc_dointvec,
1274 },
1275 { }
1276};
1277
1278static void __init kernel_reboot_sysctls_init(void)
1279{
1280 register_sysctl_init("kernel", kern_reboot_table);
1281}
1282#else
1283#define kernel_reboot_sysctls_init() do { } while (0)
1284#endif /* CONFIG_SYSCTL */
1285
1286static const struct attribute_group reboot_attr_group = {
1287 .attrs = reboot_attrs,
1288};
1289
1290static int __init reboot_ksysfs_init(void)
1291{
1292 struct kobject *reboot_kobj;
1293 int ret;
1294
1295 reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);
1296 if (!reboot_kobj)
1297 return -ENOMEM;
1298
1299 ret = sysfs_create_group(reboot_kobj, &reboot_attr_group);
1300 if (ret) {
1301 kobject_put(reboot_kobj);
1302 return ret;
1303 }
1304
1305 kernel_reboot_sysctls_init();
1306
1307 return 0;
1308}
1309late_initcall(reboot_ksysfs_init);
1310
1311#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/reboot.c
4 *
5 * Copyright (C) 2013 Linus Torvalds
6 */
7
8#define pr_fmt(fmt) "reboot: " fmt
9
10#include <linux/atomic.h>
11#include <linux/ctype.h>
12#include <linux/export.h>
13#include <linux/kexec.h>
14#include <linux/kmod.h>
15#include <linux/kmsg_dump.h>
16#include <linux/reboot.h>
17#include <linux/suspend.h>
18#include <linux/syscalls.h>
19#include <linux/syscore_ops.h>
20#include <linux/uaccess.h>
21
22/*
23 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
24 */
25
26int C_A_D = 1;
27struct pid *cad_pid;
28EXPORT_SYMBOL(cad_pid);
29
30#if defined(CONFIG_ARM)
31#define DEFAULT_REBOOT_MODE = REBOOT_HARD
32#else
33#define DEFAULT_REBOOT_MODE
34#endif
35enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
36enum reboot_mode panic_reboot_mode = REBOOT_UNDEFINED;
37
38/*
39 * This variable is used privately to keep track of whether or not
40 * reboot_type is still set to its default value (i.e., reboot= hasn't
41 * been set on the command line). This is needed so that we can
42 * suppress DMI scanning for reboot quirks. Without it, it's
43 * impossible to override a faulty reboot quirk without recompiling.
44 */
45int reboot_default = 1;
46int reboot_cpu;
47enum reboot_type reboot_type = BOOT_ACPI;
48int reboot_force;
49
50/*
51 * If set, this is used for preparing the system to power off.
52 */
53
54void (*pm_power_off_prepare)(void);
55EXPORT_SYMBOL_GPL(pm_power_off_prepare);
56
57/**
58 * emergency_restart - reboot the system
59 *
60 * Without shutting down any hardware or taking any locks
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
63 * safe to call in interrupt context.
64 */
65void emergency_restart(void)
66{
67 kmsg_dump(KMSG_DUMP_EMERG);
68 machine_emergency_restart();
69}
70EXPORT_SYMBOL_GPL(emergency_restart);
71
72void kernel_restart_prepare(char *cmd)
73{
74 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
75 system_state = SYSTEM_RESTART;
76 usermodehelper_disable();
77 device_shutdown();
78}
79
80/**
81 * register_reboot_notifier - Register function to be called at reboot time
82 * @nb: Info about notifier function to be called
83 *
84 * Registers a function with the list of functions
85 * to be called at reboot time.
86 *
87 * Currently always returns zero, as blocking_notifier_chain_register()
88 * always returns zero.
89 */
90int register_reboot_notifier(struct notifier_block *nb)
91{
92 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
93}
94EXPORT_SYMBOL(register_reboot_notifier);
95
96/**
97 * unregister_reboot_notifier - Unregister previously registered reboot notifier
98 * @nb: Hook to be unregistered
99 *
100 * Unregisters a previously registered reboot
101 * notifier function.
102 *
103 * Returns zero on success, or %-ENOENT on failure.
104 */
105int unregister_reboot_notifier(struct notifier_block *nb)
106{
107 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
108}
109EXPORT_SYMBOL(unregister_reboot_notifier);
110
111static void devm_unregister_reboot_notifier(struct device *dev, void *res)
112{
113 WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
114}
115
116int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
117{
118 struct notifier_block **rcnb;
119 int ret;
120
121 rcnb = devres_alloc(devm_unregister_reboot_notifier,
122 sizeof(*rcnb), GFP_KERNEL);
123 if (!rcnb)
124 return -ENOMEM;
125
126 ret = register_reboot_notifier(nb);
127 if (!ret) {
128 *rcnb = nb;
129 devres_add(dev, rcnb);
130 } else {
131 devres_free(rcnb);
132 }
133
134 return ret;
135}
136EXPORT_SYMBOL(devm_register_reboot_notifier);
137
138/*
139 * Notifier list for kernel code which wants to be called
140 * to restart the system.
141 */
142static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
143
144/**
145 * register_restart_handler - Register function to be called to reset
146 * the system
147 * @nb: Info about handler function to be called
148 * @nb->priority: Handler priority. Handlers should follow the
149 * following guidelines for setting priorities.
150 * 0: Restart handler of last resort,
151 * with limited restart capabilities
152 * 128: Default restart handler; use if no other
153 * restart handler is expected to be available,
154 * and/or if restart functionality is
155 * sufficient to restart the entire system
156 * 255: Highest priority restart handler, will
157 * preempt all other restart handlers
158 *
159 * Registers a function with code to be called to restart the
160 * system.
161 *
162 * Registered functions will be called from machine_restart as last
163 * step of the restart sequence (if the architecture specific
164 * machine_restart function calls do_kernel_restart - see below
165 * for details).
166 * Registered functions are expected to restart the system immediately.
167 * If more than one function is registered, the restart handler priority
168 * selects which function will be called first.
169 *
170 * Restart handlers are expected to be registered from non-architecture
171 * code, typically from drivers. A typical use case would be a system
172 * where restart functionality is provided through a watchdog. Multiple
173 * restart handlers may exist; for example, one restart handler might
174 * restart the entire system, while another only restarts the CPU.
175 * In such cases, the restart handler which only restarts part of the
176 * hardware is expected to register with low priority to ensure that
177 * it only runs if no other means to restart the system is available.
178 *
179 * Currently always returns zero, as atomic_notifier_chain_register()
180 * always returns zero.
181 */
182int register_restart_handler(struct notifier_block *nb)
183{
184 return atomic_notifier_chain_register(&restart_handler_list, nb);
185}
186EXPORT_SYMBOL(register_restart_handler);
187
188/**
189 * unregister_restart_handler - Unregister previously registered
190 * restart handler
191 * @nb: Hook to be unregistered
192 *
193 * Unregisters a previously registered restart handler function.
194 *
195 * Returns zero on success, or %-ENOENT on failure.
196 */
197int unregister_restart_handler(struct notifier_block *nb)
198{
199 return atomic_notifier_chain_unregister(&restart_handler_list, nb);
200}
201EXPORT_SYMBOL(unregister_restart_handler);
202
203/**
204 * do_kernel_restart - Execute kernel restart handler call chain
205 *
206 * Calls functions registered with register_restart_handler.
207 *
208 * Expected to be called from machine_restart as last step of the restart
209 * sequence.
210 *
211 * Restarts the system immediately if a restart handler function has been
212 * registered. Otherwise does nothing.
213 */
214void do_kernel_restart(char *cmd)
215{
216 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
217}
218
219void migrate_to_reboot_cpu(void)
220{
221 /* The boot cpu is always logical cpu 0 */
222 int cpu = reboot_cpu;
223
224 cpu_hotplug_disable();
225
226 /* Make certain the cpu I'm about to reboot on is online */
227 if (!cpu_online(cpu))
228 cpu = cpumask_first(cpu_online_mask);
229
230 /* Prevent races with other tasks migrating this task */
231 current->flags |= PF_NO_SETAFFINITY;
232
233 /* Make certain I only run on the appropriate processor */
234 set_cpus_allowed_ptr(current, cpumask_of(cpu));
235}
236
237/**
238 * kernel_restart - reboot the system
239 * @cmd: pointer to buffer containing command to execute for restart
240 * or %NULL
241 *
242 * Shutdown everything and perform a clean reboot.
243 * This is not safe to call in interrupt context.
244 */
245void kernel_restart(char *cmd)
246{
247 kernel_restart_prepare(cmd);
248 migrate_to_reboot_cpu();
249 syscore_shutdown();
250 if (!cmd)
251 pr_emerg("Restarting system\n");
252 else
253 pr_emerg("Restarting system with command '%s'\n", cmd);
254 kmsg_dump(KMSG_DUMP_SHUTDOWN);
255 machine_restart(cmd);
256}
257EXPORT_SYMBOL_GPL(kernel_restart);
258
259static void kernel_shutdown_prepare(enum system_states state)
260{
261 blocking_notifier_call_chain(&reboot_notifier_list,
262 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
263 system_state = state;
264 usermodehelper_disable();
265 device_shutdown();
266}
267/**
268 * kernel_halt - halt the system
269 *
270 * Shutdown everything and perform a clean system halt.
271 */
272void kernel_halt(void)
273{
274 kernel_shutdown_prepare(SYSTEM_HALT);
275 migrate_to_reboot_cpu();
276 syscore_shutdown();
277 pr_emerg("System halted\n");
278 kmsg_dump(KMSG_DUMP_SHUTDOWN);
279 machine_halt();
280}
281EXPORT_SYMBOL_GPL(kernel_halt);
282
283/**
284 * kernel_power_off - power_off the system
285 *
286 * Shutdown everything and perform a clean system power_off.
287 */
288void kernel_power_off(void)
289{
290 kernel_shutdown_prepare(SYSTEM_POWER_OFF);
291 if (pm_power_off_prepare)
292 pm_power_off_prepare();
293 migrate_to_reboot_cpu();
294 syscore_shutdown();
295 pr_emerg("Power down\n");
296 kmsg_dump(KMSG_DUMP_SHUTDOWN);
297 machine_power_off();
298}
299EXPORT_SYMBOL_GPL(kernel_power_off);
300
301DEFINE_MUTEX(system_transition_mutex);
302
303/*
304 * Reboot system call: for obvious reasons only root may call it,
305 * and even root needs to set up some magic numbers in the registers
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.
308 *
309 * reboot doesn't sync: do that yourself before calling this.
310 */
311SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
312 void __user *, arg)
313{
314 struct pid_namespace *pid_ns = task_active_pid_ns(current);
315 char buffer[256];
316 int ret = 0;
317
318 /* We only trust the superuser with rebooting the system. */
319 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
320 return -EPERM;
321
322 /* For safety, we require "magic" arguments. */
323 if (magic1 != LINUX_REBOOT_MAGIC1 ||
324 (magic2 != LINUX_REBOOT_MAGIC2 &&
325 magic2 != LINUX_REBOOT_MAGIC2A &&
326 magic2 != LINUX_REBOOT_MAGIC2B &&
327 magic2 != LINUX_REBOOT_MAGIC2C))
328 return -EINVAL;
329
330 /*
331 * If pid namespaces are enabled and the current task is in a child
332 * pid_namespace, the command is handled by reboot_pid_ns() which will
333 * call do_exit().
334 */
335 ret = reboot_pid_ns(pid_ns, cmd);
336 if (ret)
337 return ret;
338
339 /* Instead of trying to make the power_off code look like
340 * halt when pm_power_off is not set do it the easy way.
341 */
342 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
343 cmd = LINUX_REBOOT_CMD_HALT;
344
345 mutex_lock(&system_transition_mutex);
346 switch (cmd) {
347 case LINUX_REBOOT_CMD_RESTART:
348 kernel_restart(NULL);
349 break;
350
351 case LINUX_REBOOT_CMD_CAD_ON:
352 C_A_D = 1;
353 break;
354
355 case LINUX_REBOOT_CMD_CAD_OFF:
356 C_A_D = 0;
357 break;
358
359 case LINUX_REBOOT_CMD_HALT:
360 kernel_halt();
361 do_exit(0);
362 panic("cannot halt");
363
364 case LINUX_REBOOT_CMD_POWER_OFF:
365 kernel_power_off();
366 do_exit(0);
367 break;
368
369 case LINUX_REBOOT_CMD_RESTART2:
370 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
371 if (ret < 0) {
372 ret = -EFAULT;
373 break;
374 }
375 buffer[sizeof(buffer) - 1] = '\0';
376
377 kernel_restart(buffer);
378 break;
379
380#ifdef CONFIG_KEXEC_CORE
381 case LINUX_REBOOT_CMD_KEXEC:
382 ret = kernel_kexec();
383 break;
384#endif
385
386#ifdef CONFIG_HIBERNATION
387 case LINUX_REBOOT_CMD_SW_SUSPEND:
388 ret = hibernate();
389 break;
390#endif
391
392 default:
393 ret = -EINVAL;
394 break;
395 }
396 mutex_unlock(&system_transition_mutex);
397 return ret;
398}
399
400static void deferred_cad(struct work_struct *dummy)
401{
402 kernel_restart(NULL);
403}
404
405/*
406 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
407 * As it's called within an interrupt, it may NOT sync: the only choice
408 * is whether to reboot at once, or just ignore the ctrl-alt-del.
409 */
410void ctrl_alt_del(void)
411{
412 static DECLARE_WORK(cad_work, deferred_cad);
413
414 if (C_A_D)
415 schedule_work(&cad_work);
416 else
417 kill_cad_pid(SIGINT, 1);
418}
419
420char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
421static const char reboot_cmd[] = "/sbin/reboot";
422
423static int run_cmd(const char *cmd)
424{
425 char **argv;
426 static char *envp[] = {
427 "HOME=/",
428 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
429 NULL
430 };
431 int ret;
432 argv = argv_split(GFP_KERNEL, cmd, NULL);
433 if (argv) {
434 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
435 argv_free(argv);
436 } else {
437 ret = -ENOMEM;
438 }
439
440 return ret;
441}
442
443static int __orderly_reboot(void)
444{
445 int ret;
446
447 ret = run_cmd(reboot_cmd);
448
449 if (ret) {
450 pr_warn("Failed to start orderly reboot: forcing the issue\n");
451 emergency_sync();
452 kernel_restart(NULL);
453 }
454
455 return ret;
456}
457
458static int __orderly_poweroff(bool force)
459{
460 int ret;
461
462 ret = run_cmd(poweroff_cmd);
463
464 if (ret && force) {
465 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
466
467 /*
468 * I guess this should try to kick off some daemon to sync and
469 * poweroff asap. Or not even bother syncing if we're doing an
470 * emergency shutdown?
471 */
472 emergency_sync();
473 kernel_power_off();
474 }
475
476 return ret;
477}
478
479static bool poweroff_force;
480
481static void poweroff_work_func(struct work_struct *work)
482{
483 __orderly_poweroff(poweroff_force);
484}
485
486static DECLARE_WORK(poweroff_work, poweroff_work_func);
487
488/**
489 * orderly_poweroff - Trigger an orderly system poweroff
490 * @force: force poweroff if command execution fails
491 *
492 * This may be called from any context to trigger a system shutdown.
493 * If the orderly shutdown fails, it will force an immediate shutdown.
494 */
495void orderly_poweroff(bool force)
496{
497 if (force) /* do not override the pending "true" */
498 poweroff_force = true;
499 schedule_work(&poweroff_work);
500}
501EXPORT_SYMBOL_GPL(orderly_poweroff);
502
503static void reboot_work_func(struct work_struct *work)
504{
505 __orderly_reboot();
506}
507
508static DECLARE_WORK(reboot_work, reboot_work_func);
509
510/**
511 * orderly_reboot - Trigger an orderly system reboot
512 *
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.
515 */
516void orderly_reboot(void)
517{
518 schedule_work(&reboot_work);
519}
520EXPORT_SYMBOL_GPL(orderly_reboot);
521
522/**
523 * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay
524 * @work: work_struct associated with the emergency poweroff function
525 *
526 * This function is called in very critical situations to force
527 * a kernel poweroff after a configurable timeout value.
528 */
529static void hw_failure_emergency_poweroff_func(struct work_struct *work)
530{
531 /*
532 * We have reached here after the emergency shutdown waiting period has
533 * expired. This means orderly_poweroff has not been able to shut off
534 * the system for some reason.
535 *
536 * Try to shut down the system immediately using kernel_power_off
537 * if populated
538 */
539 pr_emerg("Hardware protection timed-out. Trying forced poweroff\n");
540 kernel_power_off();
541
542 /*
543 * Worst of the worst case trigger emergency restart
544 */
545 pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n");
546 emergency_restart();
547}
548
549static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
550 hw_failure_emergency_poweroff_func);
551
552/**
553 * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
554 *
555 * This may be called from any critical situation to trigger a system shutdown
556 * after a given period of time. If time is negative this is not scheduled.
557 */
558static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
559{
560 if (poweroff_delay_ms <= 0)
561 return;
562 schedule_delayed_work(&hw_failure_emergency_poweroff_work,
563 msecs_to_jiffies(poweroff_delay_ms));
564}
565
566/**
567 * hw_protection_shutdown - Trigger an emergency system poweroff
568 *
569 * @reason: Reason of emergency shutdown to be printed.
570 * @ms_until_forced: Time to wait for orderly shutdown before tiggering a
571 * forced shudown. Negative value disables the forced
572 * shutdown.
573 *
574 * Initiate an emergency system shutdown in order to protect hardware from
575 * further damage. Usage examples include a thermal protection or a voltage or
576 * current regulator failures.
577 * NOTE: The request is ignored if protection shutdown is already pending even
578 * if the previous request has given a large timeout for forced shutdown.
579 * Can be called from any context.
580 */
581void hw_protection_shutdown(const char *reason, int ms_until_forced)
582{
583 static atomic_t allow_proceed = ATOMIC_INIT(1);
584
585 pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
586
587 /* Shutdown should be initiated only once. */
588 if (!atomic_dec_and_test(&allow_proceed))
589 return;
590
591 /*
592 * Queue a backup emergency shutdown in the event of
593 * orderly_poweroff failure
594 */
595 hw_failure_emergency_poweroff(ms_until_forced);
596 orderly_poweroff(true);
597}
598EXPORT_SYMBOL_GPL(hw_protection_shutdown);
599
600static int __init reboot_setup(char *str)
601{
602 for (;;) {
603 enum reboot_mode *mode;
604
605 /*
606 * Having anything passed on the command line via
607 * reboot= will cause us to disable DMI checking
608 * below.
609 */
610 reboot_default = 0;
611
612 if (!strncmp(str, "panic_", 6)) {
613 mode = &panic_reboot_mode;
614 str += 6;
615 } else {
616 mode = &reboot_mode;
617 }
618
619 switch (*str) {
620 case 'w':
621 *mode = REBOOT_WARM;
622 break;
623
624 case 'c':
625 *mode = REBOOT_COLD;
626 break;
627
628 case 'h':
629 *mode = REBOOT_HARD;
630 break;
631
632 case 's':
633 /*
634 * reboot_cpu is s[mp]#### with #### being the processor
635 * to be used for rebooting. Skip 's' or 'smp' prefix.
636 */
637 str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
638
639 if (isdigit(str[0])) {
640 int cpu = simple_strtoul(str, NULL, 0);
641
642 if (cpu >= num_possible_cpus()) {
643 pr_err("Ignoring the CPU number in reboot= option. "
644 "CPU %d exceeds possible cpu number %d\n",
645 cpu, num_possible_cpus());
646 break;
647 }
648 reboot_cpu = cpu;
649 } else
650 *mode = REBOOT_SOFT;
651 break;
652
653 case 'g':
654 *mode = REBOOT_GPIO;
655 break;
656
657 case 'b':
658 case 'a':
659 case 'k':
660 case 't':
661 case 'e':
662 case 'p':
663 reboot_type = *str;
664 break;
665
666 case 'f':
667 reboot_force = 1;
668 break;
669 }
670
671 str = strchr(str, ',');
672 if (str)
673 str++;
674 else
675 break;
676 }
677 return 1;
678}
679__setup("reboot=", reboot_setup);
680
681#ifdef CONFIG_SYSFS
682
683#define REBOOT_COLD_STR "cold"
684#define REBOOT_WARM_STR "warm"
685#define REBOOT_HARD_STR "hard"
686#define REBOOT_SOFT_STR "soft"
687#define REBOOT_GPIO_STR "gpio"
688#define REBOOT_UNDEFINED_STR "undefined"
689
690#define BOOT_TRIPLE_STR "triple"
691#define BOOT_KBD_STR "kbd"
692#define BOOT_BIOS_STR "bios"
693#define BOOT_ACPI_STR "acpi"
694#define BOOT_EFI_STR "efi"
695#define BOOT_PCI_STR "pci"
696
697static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
698{
699 const char *val;
700
701 switch (reboot_mode) {
702 case REBOOT_COLD:
703 val = REBOOT_COLD_STR;
704 break;
705 case REBOOT_WARM:
706 val = REBOOT_WARM_STR;
707 break;
708 case REBOOT_HARD:
709 val = REBOOT_HARD_STR;
710 break;
711 case REBOOT_SOFT:
712 val = REBOOT_SOFT_STR;
713 break;
714 case REBOOT_GPIO:
715 val = REBOOT_GPIO_STR;
716 break;
717 default:
718 val = REBOOT_UNDEFINED_STR;
719 }
720
721 return sprintf(buf, "%s\n", val);
722}
723static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr,
724 const char *buf, size_t count)
725{
726 if (!capable(CAP_SYS_BOOT))
727 return -EPERM;
728
729 if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR)))
730 reboot_mode = REBOOT_COLD;
731 else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR)))
732 reboot_mode = REBOOT_WARM;
733 else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR)))
734 reboot_mode = REBOOT_HARD;
735 else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR)))
736 reboot_mode = REBOOT_SOFT;
737 else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR)))
738 reboot_mode = REBOOT_GPIO;
739 else
740 return -EINVAL;
741
742 reboot_default = 0;
743
744 return count;
745}
746static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
747
748#ifdef CONFIG_X86
749static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
750{
751 return sprintf(buf, "%d\n", reboot_force);
752}
753static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
754 const char *buf, size_t count)
755{
756 bool res;
757
758 if (!capable(CAP_SYS_BOOT))
759 return -EPERM;
760
761 if (kstrtobool(buf, &res))
762 return -EINVAL;
763
764 reboot_default = 0;
765 reboot_force = res;
766
767 return count;
768}
769static struct kobj_attribute reboot_force_attr = __ATTR_RW(force);
770
771static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
772{
773 const char *val;
774
775 switch (reboot_type) {
776 case BOOT_TRIPLE:
777 val = BOOT_TRIPLE_STR;
778 break;
779 case BOOT_KBD:
780 val = BOOT_KBD_STR;
781 break;
782 case BOOT_BIOS:
783 val = BOOT_BIOS_STR;
784 break;
785 case BOOT_ACPI:
786 val = BOOT_ACPI_STR;
787 break;
788 case BOOT_EFI:
789 val = BOOT_EFI_STR;
790 break;
791 case BOOT_CF9_FORCE:
792 val = BOOT_PCI_STR;
793 break;
794 default:
795 val = REBOOT_UNDEFINED_STR;
796 }
797
798 return sprintf(buf, "%s\n", val);
799}
800static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr,
801 const char *buf, size_t count)
802{
803 if (!capable(CAP_SYS_BOOT))
804 return -EPERM;
805
806 if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR)))
807 reboot_type = BOOT_TRIPLE;
808 else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR)))
809 reboot_type = BOOT_KBD;
810 else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR)))
811 reboot_type = BOOT_BIOS;
812 else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR)))
813 reboot_type = BOOT_ACPI;
814 else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR)))
815 reboot_type = BOOT_EFI;
816 else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR)))
817 reboot_type = BOOT_CF9_FORCE;
818 else
819 return -EINVAL;
820
821 reboot_default = 0;
822
823 return count;
824}
825static struct kobj_attribute reboot_type_attr = __ATTR_RW(type);
826#endif
827
828#ifdef CONFIG_SMP
829static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
830{
831 return sprintf(buf, "%d\n", reboot_cpu);
832}
833static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr,
834 const char *buf, size_t count)
835{
836 unsigned int cpunum;
837 int rc;
838
839 if (!capable(CAP_SYS_BOOT))
840 return -EPERM;
841
842 rc = kstrtouint(buf, 0, &cpunum);
843
844 if (rc)
845 return rc;
846
847 if (cpunum >= num_possible_cpus())
848 return -ERANGE;
849
850 reboot_default = 0;
851 reboot_cpu = cpunum;
852
853 return count;
854}
855static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu);
856#endif
857
858static struct attribute *reboot_attrs[] = {
859 &reboot_mode_attr.attr,
860#ifdef CONFIG_X86
861 &reboot_force_attr.attr,
862 &reboot_type_attr.attr,
863#endif
864#ifdef CONFIG_SMP
865 &reboot_cpu_attr.attr,
866#endif
867 NULL,
868};
869
870static const struct attribute_group reboot_attr_group = {
871 .attrs = reboot_attrs,
872};
873
874static int __init reboot_ksysfs_init(void)
875{
876 struct kobject *reboot_kobj;
877 int ret;
878
879 reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);
880 if (!reboot_kobj)
881 return -ENOMEM;
882
883 ret = sysfs_create_group(reboot_kobj, &reboot_attr_group);
884 if (ret) {
885 kobject_put(reboot_kobj);
886 return ret;
887 }
888
889 return 0;
890}
891late_initcall(reboot_ksysfs_init);
892
893#endif