projects/linux·blob v6.7-rc3 · refs

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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 struct device *dev;
59};
60
61/*
62 * Temporary stub that prevents linkage failure while we're in process
63 * of removing all uses of legacy pm_power_off() around the kernel.
64 */
65void __weak (*pm_power_off)(void);
66
67/**
68 * emergency_restart - reboot the system
69 *
70 * Without shutting down any hardware or taking any locks
71 * reboot the system. This is called when we know we are in
72 * trouble so this is our best effort to reboot. This is
73 * safe to call in interrupt context.
74 */
75void emergency_restart(void)
76{
77 kmsg_dump(KMSG_DUMP_EMERG);
78 system_state = SYSTEM_RESTART;
79 machine_emergency_restart();
80}
81EXPORT_SYMBOL_GPL(emergency_restart);
82
83void kernel_restart_prepare(char *cmd)
84{
85 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
86 system_state = SYSTEM_RESTART;
87 usermodehelper_disable();
88 device_shutdown();
89}
90
91/**
92 * register_reboot_notifier - Register function to be called at reboot time
93 * @nb: Info about notifier function to be called
94 *
95 * Registers a function with the list of functions
96 * to be called at reboot time.
97 *
98 * Currently always returns zero, as blocking_notifier_chain_register()
99 * always returns zero.
100 */
101int register_reboot_notifier(struct notifier_block *nb)
102{
103 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
104}
105EXPORT_SYMBOL(register_reboot_notifier);
106
107/**
108 * unregister_reboot_notifier - Unregister previously registered reboot notifier
109 * @nb: Hook to be unregistered
110 *
111 * Unregisters a previously registered reboot
112 * notifier function.
113 *
114 * Returns zero on success, or %-ENOENT on failure.
115 */
116int unregister_reboot_notifier(struct notifier_block *nb)
117{
118 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
119}
120EXPORT_SYMBOL(unregister_reboot_notifier);
121
122static void devm_unregister_reboot_notifier(struct device *dev, void *res)
123{
124 WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
125}
126
127int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
128{
129 struct notifier_block **rcnb;
130 int ret;
131
132 rcnb = devres_alloc(devm_unregister_reboot_notifier,
133 sizeof(*rcnb), GFP_KERNEL);
134 if (!rcnb)
135 return -ENOMEM;
136
137 ret = register_reboot_notifier(nb);
138 if (!ret) {
139 *rcnb = nb;
140 devres_add(dev, rcnb);
141 } else {
142 devres_free(rcnb);
143 }
144
145 return ret;
146}
147EXPORT_SYMBOL(devm_register_reboot_notifier);
148
149/*
150 * Notifier list for kernel code which wants to be called
151 * to restart the system.
152 */
153static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
154
155/**
156 * register_restart_handler - Register function to be called to reset
157 * the system
158 * @nb: Info about handler function to be called
159 * @nb->priority: Handler priority. Handlers should follow the
160 * following guidelines for setting priorities.
161 * 0: Restart handler of last resort,
162 * with limited restart capabilities
163 * 128: Default restart handler; use if no other
164 * restart handler is expected to be available,
165 * and/or if restart functionality is
166 * sufficient to restart the entire system
167 * 255: Highest priority restart handler, will
168 * preempt all other restart handlers
169 *
170 * Registers a function with code to be called to restart the
171 * system.
172 *
173 * Registered functions will be called from machine_restart as last
174 * step of the restart sequence (if the architecture specific
175 * machine_restart function calls do_kernel_restart - see below
176 * for details).
177 * Registered functions are expected to restart the system immediately.
178 * If more than one function is registered, the restart handler priority
179 * selects which function will be called first.
180 *
181 * Restart handlers are expected to be registered from non-architecture
182 * code, typically from drivers. A typical use case would be a system
183 * where restart functionality is provided through a watchdog. Multiple
184 * restart handlers may exist; for example, one restart handler might
185 * restart the entire system, while another only restarts the CPU.
186 * In such cases, the restart handler which only restarts part of the
187 * hardware is expected to register with low priority to ensure that
188 * it only runs if no other means to restart the system is available.
189 *
190 * Currently always returns zero, as atomic_notifier_chain_register()
191 * always returns zero.
192 */
193int register_restart_handler(struct notifier_block *nb)
194{
195 return atomic_notifier_chain_register(&restart_handler_list, nb);
196}
197EXPORT_SYMBOL(register_restart_handler);
198
199/**
200 * unregister_restart_handler - Unregister previously registered
201 * restart handler
202 * @nb: Hook to be unregistered
203 *
204 * Unregisters a previously registered restart handler function.
205 *
206 * Returns zero on success, or %-ENOENT on failure.
207 */
208int unregister_restart_handler(struct notifier_block *nb)
209{
210 return atomic_notifier_chain_unregister(&restart_handler_list, nb);
211}
212EXPORT_SYMBOL(unregister_restart_handler);
213
214/**
215 * do_kernel_restart - Execute kernel restart handler call chain
216 *
217 * Calls functions registered with register_restart_handler.
218 *
219 * Expected to be called from machine_restart as last step of the restart
220 * sequence.
221 *
222 * Restarts the system immediately if a restart handler function has been
223 * registered. Otherwise does nothing.
224 */
225void do_kernel_restart(char *cmd)
226{
227 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
228}
229
230void migrate_to_reboot_cpu(void)
231{
232 /* The boot cpu is always logical cpu 0 */
233 int cpu = reboot_cpu;
234
235 cpu_hotplug_disable();
236
237 /* Make certain the cpu I'm about to reboot on is online */
238 if (!cpu_online(cpu))
239 cpu = cpumask_first(cpu_online_mask);
240
241 /* Prevent races with other tasks migrating this task */
242 current->flags |= PF_NO_SETAFFINITY;
243
244 /* Make certain I only run on the appropriate processor */
245 set_cpus_allowed_ptr(current, cpumask_of(cpu));
246}
247
248/*
249 * Notifier list for kernel code which wants to be called
250 * to prepare system for restart.
251 */
252static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list);
253
254static void do_kernel_restart_prepare(void)
255{
256 blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL);
257}
258
259/**
260 * kernel_restart - reboot the system
261 * @cmd: pointer to buffer containing command to execute for restart
262 * or %NULL
263 *
264 * Shutdown everything and perform a clean reboot.
265 * This is not safe to call in interrupt context.
266 */
267void kernel_restart(char *cmd)
268{
269 kernel_restart_prepare(cmd);
270 do_kernel_restart_prepare();
271 migrate_to_reboot_cpu();
272 syscore_shutdown();
273 if (!cmd)
274 pr_emerg("Restarting system\n");
275 else
276 pr_emerg("Restarting system with command '%s'\n", cmd);
277 kmsg_dump(KMSG_DUMP_SHUTDOWN);
278 machine_restart(cmd);
279}
280EXPORT_SYMBOL_GPL(kernel_restart);
281
282static void kernel_shutdown_prepare(enum system_states state)
283{
284 blocking_notifier_call_chain(&reboot_notifier_list,
285 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
286 system_state = state;
287 usermodehelper_disable();
288 device_shutdown();
289}
290/**
291 * kernel_halt - halt the system
292 *
293 * Shutdown everything and perform a clean system halt.
294 */
295void kernel_halt(void)
296{
297 kernel_shutdown_prepare(SYSTEM_HALT);
298 migrate_to_reboot_cpu();
299 syscore_shutdown();
300 pr_emerg("System halted\n");
301 kmsg_dump(KMSG_DUMP_SHUTDOWN);
302 machine_halt();
303}
304EXPORT_SYMBOL_GPL(kernel_halt);
305
306/*
307 * Notifier list for kernel code which wants to be called
308 * to prepare system for power off.
309 */
310static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list);
311
312/*
313 * Notifier list for kernel code which wants to be called
314 * to power off system.
315 */
316static ATOMIC_NOTIFIER_HEAD(power_off_handler_list);
317
318static int sys_off_notify(struct notifier_block *nb,
319 unsigned long mode, void *cmd)
320{
321 struct sys_off_handler *handler;
322 struct sys_off_data data = {};
323
324 handler = container_of(nb, struct sys_off_handler, nb);
325 data.cb_data = handler->cb_data;
326 data.mode = mode;
327 data.cmd = cmd;
328 data.dev = handler->dev;
329
330 return handler->sys_off_cb(&data);
331}
332
333static struct sys_off_handler platform_sys_off_handler;
334
335static struct sys_off_handler *alloc_sys_off_handler(int priority)
336{
337 struct sys_off_handler *handler;
338 gfp_t flags;
339
340 /*
341 * Platforms like m68k can't allocate sys_off handler dynamically
342 * at the early boot time because memory allocator isn't available yet.
343 */
344 if (priority == SYS_OFF_PRIO_PLATFORM) {
345 handler = &platform_sys_off_handler;
346 if (handler->cb_data)
347 return ERR_PTR(-EBUSY);
348 } else {
349 if (system_state > SYSTEM_RUNNING)
350 flags = GFP_ATOMIC;
351 else
352 flags = GFP_KERNEL;
353
354 handler = kzalloc(sizeof(*handler), flags);
355 if (!handler)
356 return ERR_PTR(-ENOMEM);
357 }
358
359 return handler;
360}
361
362static void free_sys_off_handler(struct sys_off_handler *handler)
363{
364 if (handler == &platform_sys_off_handler)
365 memset(handler, 0, sizeof(*handler));
366 else
367 kfree(handler);
368}
369
370/**
371 * register_sys_off_handler - Register sys-off handler
372 * @mode: Sys-off mode
373 * @priority: Handler priority
374 * @callback: Callback function
375 * @cb_data: Callback argument
376 *
377 * Registers system power-off or restart handler that will be invoked
378 * at the step corresponding to the given sys-off mode. Handler's callback
379 * should return NOTIFY_DONE to permit execution of the next handler in
380 * the call chain or NOTIFY_STOP to break the chain (in error case for
381 * example).
382 *
383 * Multiple handlers can be registered at the default priority level.
384 *
385 * Only one handler can be registered at the non-default priority level,
386 * otherwise ERR_PTR(-EBUSY) is returned.
387 *
388 * Returns a new instance of struct sys_off_handler on success, or
389 * an ERR_PTR()-encoded error code otherwise.
390 */
391struct sys_off_handler *
392register_sys_off_handler(enum sys_off_mode mode,
393 int priority,
394 int (*callback)(struct sys_off_data *data),
395 void *cb_data)
396{
397 struct sys_off_handler *handler;
398 int err;
399
400 handler = alloc_sys_off_handler(priority);
401 if (IS_ERR(handler))
402 return handler;
403
404 switch (mode) {
405 case SYS_OFF_MODE_POWER_OFF_PREPARE:
406 handler->list = &power_off_prep_handler_list;
407 handler->blocking = true;
408 break;
409
410 case SYS_OFF_MODE_POWER_OFF:
411 handler->list = &power_off_handler_list;
412 break;
413
414 case SYS_OFF_MODE_RESTART_PREPARE:
415 handler->list = &restart_prep_handler_list;
416 handler->blocking = true;
417 break;
418
419 case SYS_OFF_MODE_RESTART:
420 handler->list = &restart_handler_list;
421 break;
422
423 default:
424 free_sys_off_handler(handler);
425 return ERR_PTR(-EINVAL);
426 }
427
428 handler->nb.notifier_call = sys_off_notify;
429 handler->nb.priority = priority;
430 handler->sys_off_cb = callback;
431 handler->cb_data = cb_data;
432 handler->mode = mode;
433
434 if (handler->blocking) {
435 if (priority == SYS_OFF_PRIO_DEFAULT)
436 err = blocking_notifier_chain_register(handler->list,
437 &handler->nb);
438 else
439 err = blocking_notifier_chain_register_unique_prio(handler->list,
440 &handler->nb);
441 } else {
442 if (priority == SYS_OFF_PRIO_DEFAULT)
443 err = atomic_notifier_chain_register(handler->list,
444 &handler->nb);
445 else
446 err = atomic_notifier_chain_register_unique_prio(handler->list,
447 &handler->nb);
448 }
449
450 if (err) {
451 free_sys_off_handler(handler);
452 return ERR_PTR(err);
453 }
454
455 return handler;
456}
457EXPORT_SYMBOL_GPL(register_sys_off_handler);
458
459/**
460 * unregister_sys_off_handler - Unregister sys-off handler
461 * @handler: Sys-off handler
462 *
463 * Unregisters given sys-off handler.
464 */
465void unregister_sys_off_handler(struct sys_off_handler *handler)
466{
467 int err;
468
469 if (IS_ERR_OR_NULL(handler))
470 return;
471
472 if (handler->blocking)
473 err = blocking_notifier_chain_unregister(handler->list,
474 &handler->nb);
475 else
476 err = atomic_notifier_chain_unregister(handler->list,
477 &handler->nb);
478
479 /* sanity check, shall never happen */
480 WARN_ON(err);
481
482 free_sys_off_handler(handler);
483}
484EXPORT_SYMBOL_GPL(unregister_sys_off_handler);
485
486static void devm_unregister_sys_off_handler(void *data)
487{
488 struct sys_off_handler *handler = data;
489
490 unregister_sys_off_handler(handler);
491}
492
493/**
494 * devm_register_sys_off_handler - Register sys-off handler
495 * @dev: Device that registers handler
496 * @mode: Sys-off mode
497 * @priority: Handler priority
498 * @callback: Callback function
499 * @cb_data: Callback argument
500 *
501 * Registers resource-managed sys-off handler.
502 *
503 * Returns zero on success, or error code on failure.
504 */
505int devm_register_sys_off_handler(struct device *dev,
506 enum sys_off_mode mode,
507 int priority,
508 int (*callback)(struct sys_off_data *data),
509 void *cb_data)
510{
511 struct sys_off_handler *handler;
512
513 handler = register_sys_off_handler(mode, priority, callback, cb_data);
514 if (IS_ERR(handler))
515 return PTR_ERR(handler);
516 handler->dev = dev;
517
518 return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler,
519 handler);
520}
521EXPORT_SYMBOL_GPL(devm_register_sys_off_handler);
522
523/**
524 * devm_register_power_off_handler - Register power-off handler
525 * @dev: Device that registers callback
526 * @callback: Callback function
527 * @cb_data: Callback's argument
528 *
529 * Registers resource-managed sys-off handler with a default priority
530 * and using power-off mode.
531 *
532 * Returns zero on success, or error code on failure.
533 */
534int devm_register_power_off_handler(struct device *dev,
535 int (*callback)(struct sys_off_data *data),
536 void *cb_data)
537{
538 return devm_register_sys_off_handler(dev,
539 SYS_OFF_MODE_POWER_OFF,
540 SYS_OFF_PRIO_DEFAULT,
541 callback, cb_data);
542}
543EXPORT_SYMBOL_GPL(devm_register_power_off_handler);
544
545/**
546 * devm_register_restart_handler - Register restart handler
547 * @dev: Device that registers callback
548 * @callback: Callback function
549 * @cb_data: Callback's argument
550 *
551 * Registers resource-managed sys-off handler with a default priority
552 * and using restart mode.
553 *
554 * Returns zero on success, or error code on failure.
555 */
556int devm_register_restart_handler(struct device *dev,
557 int (*callback)(struct sys_off_data *data),
558 void *cb_data)
559{
560 return devm_register_sys_off_handler(dev,
561 SYS_OFF_MODE_RESTART,
562 SYS_OFF_PRIO_DEFAULT,
563 callback, cb_data);
564}
565EXPORT_SYMBOL_GPL(devm_register_restart_handler);
566
567static struct sys_off_handler *platform_power_off_handler;
568
569static int platform_power_off_notify(struct sys_off_data *data)
570{
571 void (*platform_power_power_off_cb)(void) = data->cb_data;
572
573 platform_power_power_off_cb();
574
575 return NOTIFY_DONE;
576}
577
578/**
579 * register_platform_power_off - Register platform-level power-off callback
580 * @power_off: Power-off callback
581 *
582 * Registers power-off callback that will be called as last step
583 * of the power-off sequence. This callback is expected to be invoked
584 * for the last resort. Only one platform power-off callback is allowed
585 * to be registered at a time.
586 *
587 * Returns zero on success, or error code on failure.
588 */
589int register_platform_power_off(void (*power_off)(void))
590{
591 struct sys_off_handler *handler;
592
593 handler = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
594 SYS_OFF_PRIO_PLATFORM,
595 platform_power_off_notify,
596 power_off);
597 if (IS_ERR(handler))
598 return PTR_ERR(handler);
599
600 platform_power_off_handler = handler;
601
602 return 0;
603}
604EXPORT_SYMBOL_GPL(register_platform_power_off);
605
606/**
607 * unregister_platform_power_off - Unregister platform-level power-off callback
608 * @power_off: Power-off callback
609 *
610 * Unregisters previously registered platform power-off callback.
611 */
612void unregister_platform_power_off(void (*power_off)(void))
613{
614 if (platform_power_off_handler &&
615 platform_power_off_handler->cb_data == power_off) {
616 unregister_sys_off_handler(platform_power_off_handler);
617 platform_power_off_handler = NULL;
618 }
619}
620EXPORT_SYMBOL_GPL(unregister_platform_power_off);
621
622static int legacy_pm_power_off(struct sys_off_data *data)
623{
624 if (pm_power_off)
625 pm_power_off();
626
627 return NOTIFY_DONE;
628}
629
630static void do_kernel_power_off_prepare(void)
631{
632 blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL);
633}
634
635/**
636 * do_kernel_power_off - Execute kernel power-off handler call chain
637 *
638 * Expected to be called as last step of the power-off sequence.
639 *
640 * Powers off the system immediately if a power-off handler function has
641 * been registered. Otherwise does nothing.
642 */
643void do_kernel_power_off(void)
644{
645 struct sys_off_handler *sys_off = NULL;
646
647 /*
648 * Register sys-off handlers for legacy PM callback. This allows
649 * legacy PM callbacks temporary co-exist with the new sys-off API.
650 *
651 * TODO: Remove legacy handlers once all legacy PM users will be
652 * switched to the sys-off based APIs.
653 */
654 if (pm_power_off)
655 sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
656 SYS_OFF_PRIO_DEFAULT,
657 legacy_pm_power_off, NULL);
658
659 atomic_notifier_call_chain(&power_off_handler_list, 0, NULL);
660
661 unregister_sys_off_handler(sys_off);
662}
663
664/**
665 * kernel_can_power_off - check whether system can be powered off
666 *
667 * Returns true if power-off handler is registered and system can be
668 * powered off, false otherwise.
669 */
670bool kernel_can_power_off(void)
671{
672 return !atomic_notifier_call_chain_is_empty(&power_off_handler_list) ||
673 pm_power_off;
674}
675EXPORT_SYMBOL_GPL(kernel_can_power_off);
676
677/**
678 * kernel_power_off - power_off the system
679 *
680 * Shutdown everything and perform a clean system power_off.
681 */
682void kernel_power_off(void)
683{
684 kernel_shutdown_prepare(SYSTEM_POWER_OFF);
685 do_kernel_power_off_prepare();
686 migrate_to_reboot_cpu();
687 syscore_shutdown();
688 pr_emerg("Power down\n");
689 kmsg_dump(KMSG_DUMP_SHUTDOWN);
690 machine_power_off();
691}
692EXPORT_SYMBOL_GPL(kernel_power_off);
693
694DEFINE_MUTEX(system_transition_mutex);
695
696/*
697 * Reboot system call: for obvious reasons only root may call it,
698 * and even root needs to set up some magic numbers in the registers
699 * so that some mistake won't make this reboot the whole machine.
700 * You can also set the meaning of the ctrl-alt-del-key here.
701 *
702 * reboot doesn't sync: do that yourself before calling this.
703 */
704SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
705 void __user *, arg)
706{
707 struct pid_namespace *pid_ns = task_active_pid_ns(current);
708 char buffer[256];
709 int ret = 0;
710
711 /* We only trust the superuser with rebooting the system. */
712 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
713 return -EPERM;
714
715 /* For safety, we require "magic" arguments. */
716 if (magic1 != LINUX_REBOOT_MAGIC1 ||
717 (magic2 != LINUX_REBOOT_MAGIC2 &&
718 magic2 != LINUX_REBOOT_MAGIC2A &&
719 magic2 != LINUX_REBOOT_MAGIC2B &&
720 magic2 != LINUX_REBOOT_MAGIC2C))
721 return -EINVAL;
722
723 /*
724 * If pid namespaces are enabled and the current task is in a child
725 * pid_namespace, the command is handled by reboot_pid_ns() which will
726 * call do_exit().
727 */
728 ret = reboot_pid_ns(pid_ns, cmd);
729 if (ret)
730 return ret;
731
732 /* Instead of trying to make the power_off code look like
733 * halt when pm_power_off is not set do it the easy way.
734 */
735 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off())
736 cmd = LINUX_REBOOT_CMD_HALT;
737
738 mutex_lock(&system_transition_mutex);
739 switch (cmd) {
740 case LINUX_REBOOT_CMD_RESTART:
741 kernel_restart(NULL);
742 break;
743
744 case LINUX_REBOOT_CMD_CAD_ON:
745 C_A_D = 1;
746 break;
747
748 case LINUX_REBOOT_CMD_CAD_OFF:
749 C_A_D = 0;
750 break;
751
752 case LINUX_REBOOT_CMD_HALT:
753 kernel_halt();
754 do_exit(0);
755
756 case LINUX_REBOOT_CMD_POWER_OFF:
757 kernel_power_off();
758 do_exit(0);
759 break;
760
761 case LINUX_REBOOT_CMD_RESTART2:
762 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
763 if (ret < 0) {
764 ret = -EFAULT;
765 break;
766 }
767 buffer[sizeof(buffer) - 1] = '\0';
768
769 kernel_restart(buffer);
770 break;
771
772#ifdef CONFIG_KEXEC_CORE
773 case LINUX_REBOOT_CMD_KEXEC:
774 ret = kernel_kexec();
775 break;
776#endif
777
778#ifdef CONFIG_HIBERNATION
779 case LINUX_REBOOT_CMD_SW_SUSPEND:
780 ret = hibernate();
781 break;
782#endif
783
784 default:
785 ret = -EINVAL;
786 break;
787 }
788 mutex_unlock(&system_transition_mutex);
789 return ret;
790}
791
792static void deferred_cad(struct work_struct *dummy)
793{
794 kernel_restart(NULL);
795}
796
797/*
798 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
799 * As it's called within an interrupt, it may NOT sync: the only choice
800 * is whether to reboot at once, or just ignore the ctrl-alt-del.
801 */
802void ctrl_alt_del(void)
803{
804 static DECLARE_WORK(cad_work, deferred_cad);
805
806 if (C_A_D)
807 schedule_work(&cad_work);
808 else
809 kill_cad_pid(SIGINT, 1);
810}
811
812#define POWEROFF_CMD_PATH_LEN 256
813static char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
814static const char reboot_cmd[] = "/sbin/reboot";
815
816static int run_cmd(const char *cmd)
817{
818 char **argv;
819 static char *envp[] = {
820 "HOME=/",
821 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
822 NULL
823 };
824 int ret;
825 argv = argv_split(GFP_KERNEL, cmd, NULL);
826 if (argv) {
827 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
828 argv_free(argv);
829 } else {
830 ret = -ENOMEM;
831 }
832
833 return ret;
834}
835
836static int __orderly_reboot(void)
837{
838 int ret;
839
840 ret = run_cmd(reboot_cmd);
841
842 if (ret) {
843 pr_warn("Failed to start orderly reboot: forcing the issue\n");
844 emergency_sync();
845 kernel_restart(NULL);
846 }
847
848 return ret;
849}
850
851static int __orderly_poweroff(bool force)
852{
853 int ret;
854
855 ret = run_cmd(poweroff_cmd);
856
857 if (ret && force) {
858 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
859
860 /*
861 * I guess this should try to kick off some daemon to sync and
862 * poweroff asap. Or not even bother syncing if we're doing an
863 * emergency shutdown?
864 */
865 emergency_sync();
866 kernel_power_off();
867 }
868
869 return ret;
870}
871
872static bool poweroff_force;
873
874static void poweroff_work_func(struct work_struct *work)
875{
876 __orderly_poweroff(poweroff_force);
877}
878
879static DECLARE_WORK(poweroff_work, poweroff_work_func);
880
881/**
882 * orderly_poweroff - Trigger an orderly system poweroff
883 * @force: force poweroff if command execution fails
884 *
885 * This may be called from any context to trigger a system shutdown.
886 * If the orderly shutdown fails, it will force an immediate shutdown.
887 */
888void orderly_poweroff(bool force)
889{
890 if (force) /* do not override the pending "true" */
891 poweroff_force = true;
892 schedule_work(&poweroff_work);
893}
894EXPORT_SYMBOL_GPL(orderly_poweroff);
895
896static void reboot_work_func(struct work_struct *work)
897{
898 __orderly_reboot();
899}
900
901static DECLARE_WORK(reboot_work, reboot_work_func);
902
903/**
904 * orderly_reboot - Trigger an orderly system reboot
905 *
906 * This may be called from any context to trigger a system reboot.
907 * If the orderly reboot fails, it will force an immediate reboot.
908 */
909void orderly_reboot(void)
910{
911 schedule_work(&reboot_work);
912}
913EXPORT_SYMBOL_GPL(orderly_reboot);
914
915/**
916 * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay
917 * @work: work_struct associated with the emergency poweroff function
918 *
919 * This function is called in very critical situations to force
920 * a kernel poweroff after a configurable timeout value.
921 */
922static void hw_failure_emergency_poweroff_func(struct work_struct *work)
923{
924 /*
925 * We have reached here after the emergency shutdown waiting period has
926 * expired. This means orderly_poweroff has not been able to shut off
927 * the system for some reason.
928 *
929 * Try to shut down the system immediately using kernel_power_off
930 * if populated
931 */
932 pr_emerg("Hardware protection timed-out. Trying forced poweroff\n");
933 kernel_power_off();
934
935 /*
936 * Worst of the worst case trigger emergency restart
937 */
938 pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n");
939 emergency_restart();
940}
941
942static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
943 hw_failure_emergency_poweroff_func);
944
945/**
946 * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
947 *
948 * This may be called from any critical situation to trigger a system shutdown
949 * after a given period of time. If time is negative this is not scheduled.
950 */
951static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
952{
953 if (poweroff_delay_ms <= 0)
954 return;
955 schedule_delayed_work(&hw_failure_emergency_poweroff_work,
956 msecs_to_jiffies(poweroff_delay_ms));
957}
958
959/**
960 * hw_protection_shutdown - Trigger an emergency system poweroff
961 *
962 * @reason: Reason of emergency shutdown to be printed.
963 * @ms_until_forced: Time to wait for orderly shutdown before tiggering a
964 * forced shudown. Negative value disables the forced
965 * shutdown.
966 *
967 * Initiate an emergency system shutdown in order to protect hardware from
968 * further damage. Usage examples include a thermal protection or a voltage or
969 * current regulator failures.
970 * NOTE: The request is ignored if protection shutdown is already pending even
971 * if the previous request has given a large timeout for forced shutdown.
972 * Can be called from any context.
973 */
974void hw_protection_shutdown(const char *reason, int ms_until_forced)
975{
976 static atomic_t allow_proceed = ATOMIC_INIT(1);
977
978 pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
979
980 /* Shutdown should be initiated only once. */
981 if (!atomic_dec_and_test(&allow_proceed))
982 return;
983
984 /*
985 * Queue a backup emergency shutdown in the event of
986 * orderly_poweroff failure
987 */
988 hw_failure_emergency_poweroff(ms_until_forced);
989 orderly_poweroff(true);
990}
991EXPORT_SYMBOL_GPL(hw_protection_shutdown);
992
993static int __init reboot_setup(char *str)
994{
995 for (;;) {
996 enum reboot_mode *mode;
997
998 /*
999 * Having anything passed on the command line via
1000 * reboot= will cause us to disable DMI checking
1001 * below.
1002 */
1003 reboot_default = 0;
1004
1005 if (!strncmp(str, "panic_", 6)) {
1006 mode = &panic_reboot_mode;
1007 str += 6;
1008 } else {
1009 mode = &reboot_mode;
1010 }
1011
1012 switch (*str) {
1013 case 'w':
1014 *mode = REBOOT_WARM;
1015 break;
1016
1017 case 'c':
1018 *mode = REBOOT_COLD;
1019 break;
1020
1021 case 'h':
1022 *mode = REBOOT_HARD;
1023 break;
1024
1025 case 's':
1026 /*
1027 * reboot_cpu is s[mp]#### with #### being the processor
1028 * to be used for rebooting. Skip 's' or 'smp' prefix.
1029 */
1030 str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
1031
1032 if (isdigit(str[0])) {
1033 int cpu = simple_strtoul(str, NULL, 0);
1034
1035 if (cpu >= num_possible_cpus()) {
1036 pr_err("Ignoring the CPU number in reboot= option. "
1037 "CPU %d exceeds possible cpu number %d\n",
1038 cpu, num_possible_cpus());
1039 break;
1040 }
1041 reboot_cpu = cpu;
1042 } else
1043 *mode = REBOOT_SOFT;
1044 break;
1045
1046 case 'g':
1047 *mode = REBOOT_GPIO;
1048 break;
1049
1050 case 'b':
1051 case 'a':
1052 case 'k':
1053 case 't':
1054 case 'e':
1055 case 'p':
1056 reboot_type = *str;
1057 break;
1058
1059 case 'f':
1060 reboot_force = 1;
1061 break;
1062 }
1063
1064 str = strchr(str, ',');
1065 if (str)
1066 str++;
1067 else
1068 break;
1069 }
1070 return 1;
1071}
1072__setup("reboot=", reboot_setup);
1073
1074#ifdef CONFIG_SYSFS
1075
1076#define REBOOT_COLD_STR "cold"
1077#define REBOOT_WARM_STR "warm"
1078#define REBOOT_HARD_STR "hard"
1079#define REBOOT_SOFT_STR "soft"
1080#define REBOOT_GPIO_STR "gpio"
1081#define REBOOT_UNDEFINED_STR "undefined"
1082
1083#define BOOT_TRIPLE_STR "triple"
1084#define BOOT_KBD_STR "kbd"
1085#define BOOT_BIOS_STR "bios"
1086#define BOOT_ACPI_STR "acpi"
1087#define BOOT_EFI_STR "efi"
1088#define BOOT_PCI_STR "pci"
1089
1090static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1091{
1092 const char *val;
1093
1094 switch (reboot_mode) {
1095 case REBOOT_COLD:
1096 val = REBOOT_COLD_STR;
1097 break;
1098 case REBOOT_WARM:
1099 val = REBOOT_WARM_STR;
1100 break;
1101 case REBOOT_HARD:
1102 val = REBOOT_HARD_STR;
1103 break;
1104 case REBOOT_SOFT:
1105 val = REBOOT_SOFT_STR;
1106 break;
1107 case REBOOT_GPIO:
1108 val = REBOOT_GPIO_STR;
1109 break;
1110 default:
1111 val = REBOOT_UNDEFINED_STR;
1112 }
1113
1114 return sprintf(buf, "%s\n", val);
1115}
1116static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr,
1117 const char *buf, size_t count)
1118{
1119 if (!capable(CAP_SYS_BOOT))
1120 return -EPERM;
1121
1122 if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR)))
1123 reboot_mode = REBOOT_COLD;
1124 else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR)))
1125 reboot_mode = REBOOT_WARM;
1126 else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR)))
1127 reboot_mode = REBOOT_HARD;
1128 else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR)))
1129 reboot_mode = REBOOT_SOFT;
1130 else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR)))
1131 reboot_mode = REBOOT_GPIO;
1132 else
1133 return -EINVAL;
1134
1135 reboot_default = 0;
1136
1137 return count;
1138}
1139static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
1140
1141#ifdef CONFIG_X86
1142static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1143{
1144 return sprintf(buf, "%d\n", reboot_force);
1145}
1146static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
1147 const char *buf, size_t count)
1148{
1149 bool res;
1150
1151 if (!capable(CAP_SYS_BOOT))
1152 return -EPERM;
1153
1154 if (kstrtobool(buf, &res))
1155 return -EINVAL;
1156
1157 reboot_default = 0;
1158 reboot_force = res;
1159
1160 return count;
1161}
1162static struct kobj_attribute reboot_force_attr = __ATTR_RW(force);
1163
1164static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1165{
1166 const char *val;
1167
1168 switch (reboot_type) {
1169 case BOOT_TRIPLE:
1170 val = BOOT_TRIPLE_STR;
1171 break;
1172 case BOOT_KBD:
1173 val = BOOT_KBD_STR;
1174 break;
1175 case BOOT_BIOS:
1176 val = BOOT_BIOS_STR;
1177 break;
1178 case BOOT_ACPI:
1179 val = BOOT_ACPI_STR;
1180 break;
1181 case BOOT_EFI:
1182 val = BOOT_EFI_STR;
1183 break;
1184 case BOOT_CF9_FORCE:
1185 val = BOOT_PCI_STR;
1186 break;
1187 default:
1188 val = REBOOT_UNDEFINED_STR;
1189 }
1190
1191 return sprintf(buf, "%s\n", val);
1192}
1193static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr,
1194 const char *buf, size_t count)
1195{
1196 if (!capable(CAP_SYS_BOOT))
1197 return -EPERM;
1198
1199 if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR)))
1200 reboot_type = BOOT_TRIPLE;
1201 else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR)))
1202 reboot_type = BOOT_KBD;
1203 else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR)))
1204 reboot_type = BOOT_BIOS;
1205 else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR)))
1206 reboot_type = BOOT_ACPI;
1207 else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR)))
1208 reboot_type = BOOT_EFI;
1209 else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR)))
1210 reboot_type = BOOT_CF9_FORCE;
1211 else
1212 return -EINVAL;
1213
1214 reboot_default = 0;
1215
1216 return count;
1217}
1218static struct kobj_attribute reboot_type_attr = __ATTR_RW(type);
1219#endif
1220
1221#ifdef CONFIG_SMP
1222static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1223{
1224 return sprintf(buf, "%d\n", reboot_cpu);
1225}
1226static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr,
1227 const char *buf, size_t count)
1228{
1229 unsigned int cpunum;
1230 int rc;
1231
1232 if (!capable(CAP_SYS_BOOT))
1233 return -EPERM;
1234
1235 rc = kstrtouint(buf, 0, &cpunum);
1236
1237 if (rc)
1238 return rc;
1239
1240 if (cpunum >= num_possible_cpus())
1241 return -ERANGE;
1242
1243 reboot_default = 0;
1244 reboot_cpu = cpunum;
1245
1246 return count;
1247}
1248static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu);
1249#endif
1250
1251static struct attribute *reboot_attrs[] = {
1252 &reboot_mode_attr.attr,
1253#ifdef CONFIG_X86
1254 &reboot_force_attr.attr,
1255 &reboot_type_attr.attr,
1256#endif
1257#ifdef CONFIG_SMP
1258 &reboot_cpu_attr.attr,
1259#endif
1260 NULL,
1261};
1262
1263#ifdef CONFIG_SYSCTL
1264static struct ctl_table kern_reboot_table[] = {
1265 {
1266 .procname = "poweroff_cmd",
1267 .data = &poweroff_cmd,
1268 .maxlen = POWEROFF_CMD_PATH_LEN,
1269 .mode = 0644,
1270 .proc_handler = proc_dostring,
1271 },
1272 {
1273 .procname = "ctrl-alt-del",
1274 .data = &C_A_D,
1275 .maxlen = sizeof(int),
1276 .mode = 0644,
1277 .proc_handler = proc_dointvec,
1278 },
1279 { }
1280};
1281
1282static void __init kernel_reboot_sysctls_init(void)
1283{
1284 register_sysctl_init("kernel", kern_reboot_table);
1285}
1286#else
1287#define kernel_reboot_sysctls_init() do { } while (0)
1288#endif /* CONFIG_SYSCTL */
1289
1290static const struct attribute_group reboot_attr_group = {
1291 .attrs = reboot_attrs,
1292};
1293
1294static int __init reboot_ksysfs_init(void)
1295{
1296 struct kobject *reboot_kobj;
1297 int ret;
1298
1299 reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);
1300 if (!reboot_kobj)
1301 return -ENOMEM;
1302
1303 ret = sysfs_create_group(reboot_kobj, &reboot_attr_group);
1304 if (ret) {
1305 kobject_put(reboot_kobj);
1306 return ret;
1307 }
1308
1309 kernel_reboot_sysctls_init();
1310
1311 return 0;
1312}
1313late_initcall(reboot_ksysfs_init);
1314
1315#endif