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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 * This variable is used to indicate if a halt was initiated instead of a
63 * reboot when the reboot call was invoked with LINUX_REBOOT_CMD_POWER_OFF, but
64 * the system cannot be powered off. This allowes kernel_halt() to notify users
65 * of that.
66 */
67static bool poweroff_fallback_to_halt;
68
69/*
70 * Temporary stub that prevents linkage failure while we're in process
71 * of removing all uses of legacy pm_power_off() around the kernel.
72 */
73void __weak (*pm_power_off)(void);
74
75/*
76 * Notifier list for kernel code which wants to be called
77 * at shutdown. This is used to stop any idling DMA operations
78 * and the like.
79 */
80static BLOCKING_NOTIFIER_HEAD(reboot_notifier_list);
81
82/**
83 * emergency_restart - reboot the system
84 *
85 * Without shutting down any hardware or taking any locks
86 * reboot the system. This is called when we know we are in
87 * trouble so this is our best effort to reboot. This is
88 * safe to call in interrupt context.
89 */
90void emergency_restart(void)
91{
92 kmsg_dump(KMSG_DUMP_EMERG);
93 system_state = SYSTEM_RESTART;
94 machine_emergency_restart();
95}
96EXPORT_SYMBOL_GPL(emergency_restart);
97
98void kernel_restart_prepare(char *cmd)
99{
100 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
101 system_state = SYSTEM_RESTART;
102 usermodehelper_disable();
103 device_shutdown();
104}
105
106/**
107 * register_reboot_notifier - Register function to be called at reboot time
108 * @nb: Info about notifier function to be called
109 *
110 * Registers a function with the list of functions
111 * to be called at reboot time.
112 *
113 * Currently always returns zero, as blocking_notifier_chain_register()
114 * always returns zero.
115 */
116int register_reboot_notifier(struct notifier_block *nb)
117{
118 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
119}
120EXPORT_SYMBOL(register_reboot_notifier);
121
122/**
123 * unregister_reboot_notifier - Unregister previously registered reboot notifier
124 * @nb: Hook to be unregistered
125 *
126 * Unregisters a previously registered reboot
127 * notifier function.
128 *
129 * Returns zero on success, or %-ENOENT on failure.
130 */
131int unregister_reboot_notifier(struct notifier_block *nb)
132{
133 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
134}
135EXPORT_SYMBOL(unregister_reboot_notifier);
136
137static void devm_unregister_reboot_notifier(struct device *dev, void *res)
138{
139 WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
140}
141
142int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
143{
144 struct notifier_block **rcnb;
145 int ret;
146
147 rcnb = devres_alloc(devm_unregister_reboot_notifier,
148 sizeof(*rcnb), GFP_KERNEL);
149 if (!rcnb)
150 return -ENOMEM;
151
152 ret = register_reboot_notifier(nb);
153 if (!ret) {
154 *rcnb = nb;
155 devres_add(dev, rcnb);
156 } else {
157 devres_free(rcnb);
158 }
159
160 return ret;
161}
162EXPORT_SYMBOL(devm_register_reboot_notifier);
163
164/*
165 * Notifier list for kernel code which wants to be called
166 * to restart the system.
167 */
168static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
169
170/**
171 * register_restart_handler - Register function to be called to reset
172 * the system
173 * @nb: Info about handler function to be called
174 * @nb->priority: Handler priority. Handlers should follow the
175 * following guidelines for setting priorities.
176 * 0: Restart handler of last resort,
177 * with limited restart capabilities
178 * 128: Default restart handler; use if no other
179 * restart handler is expected to be available,
180 * and/or if restart functionality is
181 * sufficient to restart the entire system
182 * 255: Highest priority restart handler, will
183 * preempt all other restart handlers
184 *
185 * Registers a function with code to be called to restart the
186 * system.
187 *
188 * Registered functions will be called from machine_restart as last
189 * step of the restart sequence (if the architecture specific
190 * machine_restart function calls do_kernel_restart - see below
191 * for details).
192 * Registered functions are expected to restart the system immediately.
193 * If more than one function is registered, the restart handler priority
194 * selects which function will be called first.
195 *
196 * Restart handlers are expected to be registered from non-architecture
197 * code, typically from drivers. A typical use case would be a system
198 * where restart functionality is provided through a watchdog. Multiple
199 * restart handlers may exist; for example, one restart handler might
200 * restart the entire system, while another only restarts the CPU.
201 * In such cases, the restart handler which only restarts part of the
202 * hardware is expected to register with low priority to ensure that
203 * it only runs if no other means to restart the system is available.
204 *
205 * Currently always returns zero, as atomic_notifier_chain_register()
206 * always returns zero.
207 */
208int register_restart_handler(struct notifier_block *nb)
209{
210 return atomic_notifier_chain_register(&restart_handler_list, nb);
211}
212EXPORT_SYMBOL(register_restart_handler);
213
214/**
215 * unregister_restart_handler - Unregister previously registered
216 * restart handler
217 * @nb: Hook to be unregistered
218 *
219 * Unregisters a previously registered restart handler function.
220 *
221 * Returns zero on success, or %-ENOENT on failure.
222 */
223int unregister_restart_handler(struct notifier_block *nb)
224{
225 return atomic_notifier_chain_unregister(&restart_handler_list, nb);
226}
227EXPORT_SYMBOL(unregister_restart_handler);
228
229/**
230 * do_kernel_restart - Execute kernel restart handler call chain
231 *
232 * Calls functions registered with register_restart_handler.
233 *
234 * Expected to be called from machine_restart as last step of the restart
235 * sequence.
236 *
237 * Restarts the system immediately if a restart handler function has been
238 * registered. Otherwise does nothing.
239 */
240void do_kernel_restart(char *cmd)
241{
242 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
243}
244
245void migrate_to_reboot_cpu(void)
246{
247 /* The boot cpu is always logical cpu 0 */
248 int cpu = reboot_cpu;
249
250 cpu_hotplug_disable();
251
252 /* Make certain the cpu I'm about to reboot on is online */
253 if (!cpu_online(cpu))
254 cpu = cpumask_first(cpu_online_mask);
255
256 /* Prevent races with other tasks migrating this task */
257 current->flags |= PF_NO_SETAFFINITY;
258
259 /* Make certain I only run on the appropriate processor */
260 set_cpus_allowed_ptr(current, cpumask_of(cpu));
261}
262
263/*
264 * Notifier list for kernel code which wants to be called
265 * to prepare system for restart.
266 */
267static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list);
268
269static void do_kernel_restart_prepare(void)
270{
271 blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL);
272}
273
274/**
275 * kernel_restart - reboot the system
276 * @cmd: pointer to buffer containing command to execute for restart
277 * or %NULL
278 *
279 * Shutdown everything and perform a clean reboot.
280 * This is not safe to call in interrupt context.
281 */
282void kernel_restart(char *cmd)
283{
284 kernel_restart_prepare(cmd);
285 do_kernel_restart_prepare();
286 migrate_to_reboot_cpu();
287 syscore_shutdown();
288 if (!cmd)
289 pr_emerg("Restarting system\n");
290 else
291 pr_emerg("Restarting system with command '%s'\n", cmd);
292 kmsg_dump(KMSG_DUMP_SHUTDOWN);
293 machine_restart(cmd);
294}
295EXPORT_SYMBOL_GPL(kernel_restart);
296
297static void kernel_shutdown_prepare(enum system_states state)
298{
299 blocking_notifier_call_chain(&reboot_notifier_list,
300 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
301 system_state = state;
302 usermodehelper_disable();
303 device_shutdown();
304}
305/**
306 * kernel_halt - halt the system
307 *
308 * Shutdown everything and perform a clean system halt.
309 */
310void kernel_halt(void)
311{
312 kernel_shutdown_prepare(SYSTEM_HALT);
313 migrate_to_reboot_cpu();
314 syscore_shutdown();
315 if (poweroff_fallback_to_halt)
316 pr_emerg("Power off not available: System halted instead\n");
317 else
318 pr_emerg("System halted\n");
319 kmsg_dump(KMSG_DUMP_SHUTDOWN);
320 machine_halt();
321}
322EXPORT_SYMBOL_GPL(kernel_halt);
323
324/*
325 * Notifier list for kernel code which wants to be called
326 * to prepare system for power off.
327 */
328static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list);
329
330/*
331 * Notifier list for kernel code which wants to be called
332 * to power off system.
333 */
334static ATOMIC_NOTIFIER_HEAD(power_off_handler_list);
335
336static int sys_off_notify(struct notifier_block *nb,
337 unsigned long mode, void *cmd)
338{
339 struct sys_off_handler *handler;
340 struct sys_off_data data = {};
341
342 handler = container_of(nb, struct sys_off_handler, nb);
343 data.cb_data = handler->cb_data;
344 data.mode = mode;
345 data.cmd = cmd;
346 data.dev = handler->dev;
347
348 return handler->sys_off_cb(&data);
349}
350
351static struct sys_off_handler platform_sys_off_handler;
352
353static struct sys_off_handler *alloc_sys_off_handler(int priority)
354{
355 struct sys_off_handler *handler;
356 gfp_t flags;
357
358 /*
359 * Platforms like m68k can't allocate sys_off handler dynamically
360 * at the early boot time because memory allocator isn't available yet.
361 */
362 if (priority == SYS_OFF_PRIO_PLATFORM) {
363 handler = &platform_sys_off_handler;
364 if (handler->cb_data)
365 return ERR_PTR(-EBUSY);
366 } else {
367 if (system_state > SYSTEM_RUNNING)
368 flags = GFP_ATOMIC;
369 else
370 flags = GFP_KERNEL;
371
372 handler = kzalloc(sizeof(*handler), flags);
373 if (!handler)
374 return ERR_PTR(-ENOMEM);
375 }
376
377 return handler;
378}
379
380static void free_sys_off_handler(struct sys_off_handler *handler)
381{
382 if (handler == &platform_sys_off_handler)
383 memset(handler, 0, sizeof(*handler));
384 else
385 kfree(handler);
386}
387
388/**
389 * register_sys_off_handler - Register sys-off handler
390 * @mode: Sys-off mode
391 * @priority: Handler priority
392 * @callback: Callback function
393 * @cb_data: Callback argument
394 *
395 * Registers system power-off or restart handler that will be invoked
396 * at the step corresponding to the given sys-off mode. Handler's callback
397 * should return NOTIFY_DONE to permit execution of the next handler in
398 * the call chain or NOTIFY_STOP to break the chain (in error case for
399 * example).
400 *
401 * Multiple handlers can be registered at the default priority level.
402 *
403 * Only one handler can be registered at the non-default priority level,
404 * otherwise ERR_PTR(-EBUSY) is returned.
405 *
406 * Returns a new instance of struct sys_off_handler on success, or
407 * an ERR_PTR()-encoded error code otherwise.
408 */
409struct sys_off_handler *
410register_sys_off_handler(enum sys_off_mode mode,
411 int priority,
412 int (*callback)(struct sys_off_data *data),
413 void *cb_data)
414{
415 struct sys_off_handler *handler;
416 int err;
417
418 handler = alloc_sys_off_handler(priority);
419 if (IS_ERR(handler))
420 return handler;
421
422 switch (mode) {
423 case SYS_OFF_MODE_POWER_OFF_PREPARE:
424 handler->list = &power_off_prep_handler_list;
425 handler->blocking = true;
426 break;
427
428 case SYS_OFF_MODE_POWER_OFF:
429 handler->list = &power_off_handler_list;
430 break;
431
432 case SYS_OFF_MODE_RESTART_PREPARE:
433 handler->list = &restart_prep_handler_list;
434 handler->blocking = true;
435 break;
436
437 case SYS_OFF_MODE_RESTART:
438 handler->list = &restart_handler_list;
439 break;
440
441 default:
442 free_sys_off_handler(handler);
443 return ERR_PTR(-EINVAL);
444 }
445
446 handler->nb.notifier_call = sys_off_notify;
447 handler->nb.priority = priority;
448 handler->sys_off_cb = callback;
449 handler->cb_data = cb_data;
450 handler->mode = mode;
451
452 if (handler->blocking) {
453 if (priority == SYS_OFF_PRIO_DEFAULT)
454 err = blocking_notifier_chain_register(handler->list,
455 &handler->nb);
456 else
457 err = blocking_notifier_chain_register_unique_prio(handler->list,
458 &handler->nb);
459 } else {
460 if (priority == SYS_OFF_PRIO_DEFAULT)
461 err = atomic_notifier_chain_register(handler->list,
462 &handler->nb);
463 else
464 err = atomic_notifier_chain_register_unique_prio(handler->list,
465 &handler->nb);
466 }
467
468 if (err) {
469 free_sys_off_handler(handler);
470 return ERR_PTR(err);
471 }
472
473 return handler;
474}
475EXPORT_SYMBOL_GPL(register_sys_off_handler);
476
477/**
478 * unregister_sys_off_handler - Unregister sys-off handler
479 * @handler: Sys-off handler
480 *
481 * Unregisters given sys-off handler.
482 */
483void unregister_sys_off_handler(struct sys_off_handler *handler)
484{
485 int err;
486
487 if (IS_ERR_OR_NULL(handler))
488 return;
489
490 if (handler->blocking)
491 err = blocking_notifier_chain_unregister(handler->list,
492 &handler->nb);
493 else
494 err = atomic_notifier_chain_unregister(handler->list,
495 &handler->nb);
496
497 /* sanity check, shall never happen */
498 WARN_ON(err);
499
500 free_sys_off_handler(handler);
501}
502EXPORT_SYMBOL_GPL(unregister_sys_off_handler);
503
504static void devm_unregister_sys_off_handler(void *data)
505{
506 struct sys_off_handler *handler = data;
507
508 unregister_sys_off_handler(handler);
509}
510
511/**
512 * devm_register_sys_off_handler - Register sys-off handler
513 * @dev: Device that registers handler
514 * @mode: Sys-off mode
515 * @priority: Handler priority
516 * @callback: Callback function
517 * @cb_data: Callback argument
518 *
519 * Registers resource-managed sys-off handler.
520 *
521 * Returns zero on success, or error code on failure.
522 */
523int devm_register_sys_off_handler(struct device *dev,
524 enum sys_off_mode mode,
525 int priority,
526 int (*callback)(struct sys_off_data *data),
527 void *cb_data)
528{
529 struct sys_off_handler *handler;
530
531 handler = register_sys_off_handler(mode, priority, callback, cb_data);
532 if (IS_ERR(handler))
533 return PTR_ERR(handler);
534 handler->dev = dev;
535
536 return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler,
537 handler);
538}
539EXPORT_SYMBOL_GPL(devm_register_sys_off_handler);
540
541/**
542 * devm_register_power_off_handler - Register power-off 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 power-off mode.
549 *
550 * Returns zero on success, or error code on failure.
551 */
552int devm_register_power_off_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_POWER_OFF,
558 SYS_OFF_PRIO_DEFAULT,
559 callback, cb_data);
560}
561EXPORT_SYMBOL_GPL(devm_register_power_off_handler);
562
563/**
564 * devm_register_restart_handler - Register restart handler
565 * @dev: Device that registers callback
566 * @callback: Callback function
567 * @cb_data: Callback's argument
568 *
569 * Registers resource-managed sys-off handler with a default priority
570 * and using restart mode.
571 *
572 * Returns zero on success, or error code on failure.
573 */
574int devm_register_restart_handler(struct device *dev,
575 int (*callback)(struct sys_off_data *data),
576 void *cb_data)
577{
578 return devm_register_sys_off_handler(dev,
579 SYS_OFF_MODE_RESTART,
580 SYS_OFF_PRIO_DEFAULT,
581 callback, cb_data);
582}
583EXPORT_SYMBOL_GPL(devm_register_restart_handler);
584
585static struct sys_off_handler *platform_power_off_handler;
586
587static int platform_power_off_notify(struct sys_off_data *data)
588{
589 void (*platform_power_power_off_cb)(void) = data->cb_data;
590
591 platform_power_power_off_cb();
592
593 return NOTIFY_DONE;
594}
595
596/**
597 * register_platform_power_off - Register platform-level power-off callback
598 * @power_off: Power-off callback
599 *
600 * Registers power-off callback that will be called as last step
601 * of the power-off sequence. This callback is expected to be invoked
602 * for the last resort. Only one platform power-off callback is allowed
603 * to be registered at a time.
604 *
605 * Returns zero on success, or error code on failure.
606 */
607int register_platform_power_off(void (*power_off)(void))
608{
609 struct sys_off_handler *handler;
610
611 handler = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
612 SYS_OFF_PRIO_PLATFORM,
613 platform_power_off_notify,
614 power_off);
615 if (IS_ERR(handler))
616 return PTR_ERR(handler);
617
618 platform_power_off_handler = handler;
619
620 return 0;
621}
622EXPORT_SYMBOL_GPL(register_platform_power_off);
623
624/**
625 * unregister_platform_power_off - Unregister platform-level power-off callback
626 * @power_off: Power-off callback
627 *
628 * Unregisters previously registered platform power-off callback.
629 */
630void unregister_platform_power_off(void (*power_off)(void))
631{
632 if (platform_power_off_handler &&
633 platform_power_off_handler->cb_data == power_off) {
634 unregister_sys_off_handler(platform_power_off_handler);
635 platform_power_off_handler = NULL;
636 }
637}
638EXPORT_SYMBOL_GPL(unregister_platform_power_off);
639
640static int legacy_pm_power_off(struct sys_off_data *data)
641{
642 if (pm_power_off)
643 pm_power_off();
644
645 return NOTIFY_DONE;
646}
647
648static void do_kernel_power_off_prepare(void)
649{
650 blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL);
651}
652
653/**
654 * do_kernel_power_off - Execute kernel power-off handler call chain
655 *
656 * Expected to be called as last step of the power-off sequence.
657 *
658 * Powers off the system immediately if a power-off handler function has
659 * been registered. Otherwise does nothing.
660 */
661void do_kernel_power_off(void)
662{
663 struct sys_off_handler *sys_off = NULL;
664
665 /*
666 * Register sys-off handlers for legacy PM callback. This allows
667 * legacy PM callbacks temporary co-exist with the new sys-off API.
668 *
669 * TODO: Remove legacy handlers once all legacy PM users will be
670 * switched to the sys-off based APIs.
671 */
672 if (pm_power_off)
673 sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF,
674 SYS_OFF_PRIO_DEFAULT,
675 legacy_pm_power_off, NULL);
676
677 atomic_notifier_call_chain(&power_off_handler_list, 0, NULL);
678
679 unregister_sys_off_handler(sys_off);
680}
681
682/**
683 * kernel_can_power_off - check whether system can be powered off
684 *
685 * Returns true if power-off handler is registered and system can be
686 * powered off, false otherwise.
687 */
688bool kernel_can_power_off(void)
689{
690 return !atomic_notifier_call_chain_is_empty(&power_off_handler_list) ||
691 pm_power_off;
692}
693EXPORT_SYMBOL_GPL(kernel_can_power_off);
694
695/**
696 * kernel_power_off - power_off the system
697 *
698 * Shutdown everything and perform a clean system power_off.
699 */
700void kernel_power_off(void)
701{
702 kernel_shutdown_prepare(SYSTEM_POWER_OFF);
703 do_kernel_power_off_prepare();
704 migrate_to_reboot_cpu();
705 syscore_shutdown();
706 pr_emerg("Power down\n");
707 kmsg_dump(KMSG_DUMP_SHUTDOWN);
708 machine_power_off();
709}
710EXPORT_SYMBOL_GPL(kernel_power_off);
711
712DEFINE_MUTEX(system_transition_mutex);
713
714/*
715 * Reboot system call: for obvious reasons only root may call it,
716 * and even root needs to set up some magic numbers in the registers
717 * so that some mistake won't make this reboot the whole machine.
718 * You can also set the meaning of the ctrl-alt-del-key here.
719 *
720 * reboot doesn't sync: do that yourself before calling this.
721 */
722SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
723 void __user *, arg)
724{
725 struct pid_namespace *pid_ns = task_active_pid_ns(current);
726 char buffer[256];
727 int ret = 0;
728
729 /* We only trust the superuser with rebooting the system. */
730 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
731 return -EPERM;
732
733 /* For safety, we require "magic" arguments. */
734 if (magic1 != LINUX_REBOOT_MAGIC1 ||
735 (magic2 != LINUX_REBOOT_MAGIC2 &&
736 magic2 != LINUX_REBOOT_MAGIC2A &&
737 magic2 != LINUX_REBOOT_MAGIC2B &&
738 magic2 != LINUX_REBOOT_MAGIC2C))
739 return -EINVAL;
740
741 /*
742 * If pid namespaces are enabled and the current task is in a child
743 * pid_namespace, the command is handled by reboot_pid_ns() which will
744 * call do_exit().
745 */
746 ret = reboot_pid_ns(pid_ns, cmd);
747 if (ret)
748 return ret;
749
750 /* Instead of trying to make the power_off code look like
751 * halt when pm_power_off is not set do it the easy way.
752 */
753 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off()) {
754 poweroff_fallback_to_halt = true;
755 cmd = LINUX_REBOOT_CMD_HALT;
756 }
757
758 mutex_lock(&system_transition_mutex);
759 switch (cmd) {
760 case LINUX_REBOOT_CMD_RESTART:
761 kernel_restart(NULL);
762 break;
763
764 case LINUX_REBOOT_CMD_CAD_ON:
765 C_A_D = 1;
766 break;
767
768 case LINUX_REBOOT_CMD_CAD_OFF:
769 C_A_D = 0;
770 break;
771
772 case LINUX_REBOOT_CMD_HALT:
773 kernel_halt();
774 do_exit(0);
775
776 case LINUX_REBOOT_CMD_POWER_OFF:
777 kernel_power_off();
778 do_exit(0);
779 break;
780
781 case LINUX_REBOOT_CMD_RESTART2:
782 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
783 if (ret < 0) {
784 ret = -EFAULT;
785 break;
786 }
787 buffer[sizeof(buffer) - 1] = '\0';
788
789 kernel_restart(buffer);
790 break;
791
792#ifdef CONFIG_KEXEC_CORE
793 case LINUX_REBOOT_CMD_KEXEC:
794 ret = kernel_kexec();
795 break;
796#endif
797
798#ifdef CONFIG_HIBERNATION
799 case LINUX_REBOOT_CMD_SW_SUSPEND:
800 ret = hibernate();
801 break;
802#endif
803
804 default:
805 ret = -EINVAL;
806 break;
807 }
808 mutex_unlock(&system_transition_mutex);
809 return ret;
810}
811
812static void deferred_cad(struct work_struct *dummy)
813{
814 kernel_restart(NULL);
815}
816
817/*
818 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
819 * As it's called within an interrupt, it may NOT sync: the only choice
820 * is whether to reboot at once, or just ignore the ctrl-alt-del.
821 */
822void ctrl_alt_del(void)
823{
824 static DECLARE_WORK(cad_work, deferred_cad);
825
826 if (C_A_D)
827 schedule_work(&cad_work);
828 else
829 kill_cad_pid(SIGINT, 1);
830}
831
832#define POWEROFF_CMD_PATH_LEN 256
833static char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
834static const char reboot_cmd[] = "/sbin/reboot";
835
836static int run_cmd(const char *cmd)
837{
838 char **argv;
839 static char *envp[] = {
840 "HOME=/",
841 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
842 NULL
843 };
844 int ret;
845 argv = argv_split(GFP_KERNEL, cmd, NULL);
846 if (argv) {
847 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
848 argv_free(argv);
849 } else {
850 ret = -ENOMEM;
851 }
852
853 return ret;
854}
855
856static int __orderly_reboot(void)
857{
858 int ret;
859
860 ret = run_cmd(reboot_cmd);
861
862 if (ret) {
863 pr_warn("Failed to start orderly reboot: forcing the issue\n");
864 emergency_sync();
865 kernel_restart(NULL);
866 }
867
868 return ret;
869}
870
871static int __orderly_poweroff(bool force)
872{
873 int ret;
874
875 ret = run_cmd(poweroff_cmd);
876
877 if (ret && force) {
878 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
879
880 /*
881 * I guess this should try to kick off some daemon to sync and
882 * poweroff asap. Or not even bother syncing if we're doing an
883 * emergency shutdown?
884 */
885 emergency_sync();
886 kernel_power_off();
887 }
888
889 return ret;
890}
891
892static bool poweroff_force;
893
894static void poweroff_work_func(struct work_struct *work)
895{
896 __orderly_poweroff(poweroff_force);
897}
898
899static DECLARE_WORK(poweroff_work, poweroff_work_func);
900
901/**
902 * orderly_poweroff - Trigger an orderly system poweroff
903 * @force: force poweroff if command execution fails
904 *
905 * This may be called from any context to trigger a system shutdown.
906 * If the orderly shutdown fails, it will force an immediate shutdown.
907 */
908void orderly_poweroff(bool force)
909{
910 if (force) /* do not override the pending "true" */
911 poweroff_force = true;
912 schedule_work(&poweroff_work);
913}
914EXPORT_SYMBOL_GPL(orderly_poweroff);
915
916static void reboot_work_func(struct work_struct *work)
917{
918 __orderly_reboot();
919}
920
921static DECLARE_WORK(reboot_work, reboot_work_func);
922
923/**
924 * orderly_reboot - Trigger an orderly system reboot
925 *
926 * This may be called from any context to trigger a system reboot.
927 * If the orderly reboot fails, it will force an immediate reboot.
928 */
929void orderly_reboot(void)
930{
931 schedule_work(&reboot_work);
932}
933EXPORT_SYMBOL_GPL(orderly_reboot);
934
935/**
936 * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay
937 * @work: work_struct associated with the emergency poweroff function
938 *
939 * This function is called in very critical situations to force
940 * a kernel poweroff after a configurable timeout value.
941 */
942static void hw_failure_emergency_poweroff_func(struct work_struct *work)
943{
944 /*
945 * We have reached here after the emergency shutdown waiting period has
946 * expired. This means orderly_poweroff has not been able to shut off
947 * the system for some reason.
948 *
949 * Try to shut down the system immediately using kernel_power_off
950 * if populated
951 */
952 pr_emerg("Hardware protection timed-out. Trying forced poweroff\n");
953 kernel_power_off();
954
955 /*
956 * Worst of the worst case trigger emergency restart
957 */
958 pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n");
959 emergency_restart();
960}
961
962static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work,
963 hw_failure_emergency_poweroff_func);
964
965/**
966 * hw_failure_emergency_poweroff - Trigger an emergency system poweroff
967 *
968 * This may be called from any critical situation to trigger a system shutdown
969 * after a given period of time. If time is negative this is not scheduled.
970 */
971static void hw_failure_emergency_poweroff(int poweroff_delay_ms)
972{
973 if (poweroff_delay_ms <= 0)
974 return;
975 schedule_delayed_work(&hw_failure_emergency_poweroff_work,
976 msecs_to_jiffies(poweroff_delay_ms));
977}
978
979/**
980 * __hw_protection_shutdown - Trigger an emergency system shutdown or reboot
981 *
982 * @reason: Reason of emergency shutdown or reboot to be printed.
983 * @ms_until_forced: Time to wait for orderly shutdown or reboot before
984 * triggering it. Negative value disables the forced
985 * shutdown or reboot.
986 * @shutdown: If true, indicates that a shutdown will happen
987 * after the critical tempeature is reached.
988 * If false, indicates that a reboot will happen
989 * after the critical tempeature is reached.
990 *
991 * Initiate an emergency system shutdown or reboot in order to protect
992 * hardware from further damage. Usage examples include a thermal protection.
993 * NOTE: The request is ignored if protection shutdown or reboot is already
994 * pending even if the previous request has given a large timeout for forced
995 * shutdown/reboot.
996 */
997void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shutdown)
998{
999 static atomic_t allow_proceed = ATOMIC_INIT(1);
1000
1001 pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason);
1002
1003 /* Shutdown should be initiated only once. */
1004 if (!atomic_dec_and_test(&allow_proceed))
1005 return;
1006
1007 /*
1008 * Queue a backup emergency shutdown in the event of
1009 * orderly_poweroff failure
1010 */
1011 hw_failure_emergency_poweroff(ms_until_forced);
1012 if (shutdown)
1013 orderly_poweroff(true);
1014 else
1015 orderly_reboot();
1016}
1017EXPORT_SYMBOL_GPL(__hw_protection_shutdown);
1018
1019static int __init reboot_setup(char *str)
1020{
1021 for (;;) {
1022 enum reboot_mode *mode;
1023
1024 /*
1025 * Having anything passed on the command line via
1026 * reboot= will cause us to disable DMI checking
1027 * below.
1028 */
1029 reboot_default = 0;
1030
1031 if (!strncmp(str, "panic_", 6)) {
1032 mode = &panic_reboot_mode;
1033 str += 6;
1034 } else {
1035 mode = &reboot_mode;
1036 }
1037
1038 switch (*str) {
1039 case 'w':
1040 *mode = REBOOT_WARM;
1041 break;
1042
1043 case 'c':
1044 *mode = REBOOT_COLD;
1045 break;
1046
1047 case 'h':
1048 *mode = REBOOT_HARD;
1049 break;
1050
1051 case 's':
1052 /*
1053 * reboot_cpu is s[mp]#### with #### being the processor
1054 * to be used for rebooting. Skip 's' or 'smp' prefix.
1055 */
1056 str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
1057
1058 if (isdigit(str[0])) {
1059 int cpu = simple_strtoul(str, NULL, 0);
1060
1061 if (cpu >= num_possible_cpus()) {
1062 pr_err("Ignoring the CPU number in reboot= option. "
1063 "CPU %d exceeds possible cpu number %d\n",
1064 cpu, num_possible_cpus());
1065 break;
1066 }
1067 reboot_cpu = cpu;
1068 } else
1069 *mode = REBOOT_SOFT;
1070 break;
1071
1072 case 'g':
1073 *mode = REBOOT_GPIO;
1074 break;
1075
1076 case 'b':
1077 case 'a':
1078 case 'k':
1079 case 't':
1080 case 'e':
1081 case 'p':
1082 reboot_type = *str;
1083 break;
1084
1085 case 'f':
1086 reboot_force = 1;
1087 break;
1088 }
1089
1090 str = strchr(str, ',');
1091 if (str)
1092 str++;
1093 else
1094 break;
1095 }
1096 return 1;
1097}
1098__setup("reboot=", reboot_setup);
1099
1100#ifdef CONFIG_SYSFS
1101
1102#define REBOOT_COLD_STR "cold"
1103#define REBOOT_WARM_STR "warm"
1104#define REBOOT_HARD_STR "hard"
1105#define REBOOT_SOFT_STR "soft"
1106#define REBOOT_GPIO_STR "gpio"
1107#define REBOOT_UNDEFINED_STR "undefined"
1108
1109#define BOOT_TRIPLE_STR "triple"
1110#define BOOT_KBD_STR "kbd"
1111#define BOOT_BIOS_STR "bios"
1112#define BOOT_ACPI_STR "acpi"
1113#define BOOT_EFI_STR "efi"
1114#define BOOT_PCI_STR "pci"
1115
1116static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1117{
1118 const char *val;
1119
1120 switch (reboot_mode) {
1121 case REBOOT_COLD:
1122 val = REBOOT_COLD_STR;
1123 break;
1124 case REBOOT_WARM:
1125 val = REBOOT_WARM_STR;
1126 break;
1127 case REBOOT_HARD:
1128 val = REBOOT_HARD_STR;
1129 break;
1130 case REBOOT_SOFT:
1131 val = REBOOT_SOFT_STR;
1132 break;
1133 case REBOOT_GPIO:
1134 val = REBOOT_GPIO_STR;
1135 break;
1136 default:
1137 val = REBOOT_UNDEFINED_STR;
1138 }
1139
1140 return sysfs_emit(buf, "%s\n", val);
1141}
1142static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr,
1143 const char *buf, size_t count)
1144{
1145 if (!capable(CAP_SYS_BOOT))
1146 return -EPERM;
1147
1148 if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR)))
1149 reboot_mode = REBOOT_COLD;
1150 else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR)))
1151 reboot_mode = REBOOT_WARM;
1152 else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR)))
1153 reboot_mode = REBOOT_HARD;
1154 else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR)))
1155 reboot_mode = REBOOT_SOFT;
1156 else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR)))
1157 reboot_mode = REBOOT_GPIO;
1158 else
1159 return -EINVAL;
1160
1161 reboot_default = 0;
1162
1163 return count;
1164}
1165static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
1166
1167#ifdef CONFIG_X86
1168static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1169{
1170 return sysfs_emit(buf, "%d\n", reboot_force);
1171}
1172static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
1173 const char *buf, size_t count)
1174{
1175 bool res;
1176
1177 if (!capable(CAP_SYS_BOOT))
1178 return -EPERM;
1179
1180 if (kstrtobool(buf, &res))
1181 return -EINVAL;
1182
1183 reboot_default = 0;
1184 reboot_force = res;
1185
1186 return count;
1187}
1188static struct kobj_attribute reboot_force_attr = __ATTR_RW(force);
1189
1190static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1191{
1192 const char *val;
1193
1194 switch (reboot_type) {
1195 case BOOT_TRIPLE:
1196 val = BOOT_TRIPLE_STR;
1197 break;
1198 case BOOT_KBD:
1199 val = BOOT_KBD_STR;
1200 break;
1201 case BOOT_BIOS:
1202 val = BOOT_BIOS_STR;
1203 break;
1204 case BOOT_ACPI:
1205 val = BOOT_ACPI_STR;
1206 break;
1207 case BOOT_EFI:
1208 val = BOOT_EFI_STR;
1209 break;
1210 case BOOT_CF9_FORCE:
1211 val = BOOT_PCI_STR;
1212 break;
1213 default:
1214 val = REBOOT_UNDEFINED_STR;
1215 }
1216
1217 return sysfs_emit(buf, "%s\n", val);
1218}
1219static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr,
1220 const char *buf, size_t count)
1221{
1222 if (!capable(CAP_SYS_BOOT))
1223 return -EPERM;
1224
1225 if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR)))
1226 reboot_type = BOOT_TRIPLE;
1227 else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR)))
1228 reboot_type = BOOT_KBD;
1229 else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR)))
1230 reboot_type = BOOT_BIOS;
1231 else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR)))
1232 reboot_type = BOOT_ACPI;
1233 else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR)))
1234 reboot_type = BOOT_EFI;
1235 else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR)))
1236 reboot_type = BOOT_CF9_FORCE;
1237 else
1238 return -EINVAL;
1239
1240 reboot_default = 0;
1241
1242 return count;
1243}
1244static struct kobj_attribute reboot_type_attr = __ATTR_RW(type);
1245#endif
1246
1247#ifdef CONFIG_SMP
1248static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1249{
1250 return sysfs_emit(buf, "%d\n", reboot_cpu);
1251}
1252static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr,
1253 const char *buf, size_t count)
1254{
1255 unsigned int cpunum;
1256 int rc;
1257
1258 if (!capable(CAP_SYS_BOOT))
1259 return -EPERM;
1260
1261 rc = kstrtouint(buf, 0, &cpunum);
1262
1263 if (rc)
1264 return rc;
1265
1266 if (cpunum >= num_possible_cpus())
1267 return -ERANGE;
1268
1269 reboot_default = 0;
1270 reboot_cpu = cpunum;
1271
1272 return count;
1273}
1274static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu);
1275#endif
1276
1277static struct attribute *reboot_attrs[] = {
1278 &reboot_mode_attr.attr,
1279#ifdef CONFIG_X86
1280 &reboot_force_attr.attr,
1281 &reboot_type_attr.attr,
1282#endif
1283#ifdef CONFIG_SMP
1284 &reboot_cpu_attr.attr,
1285#endif
1286 NULL,
1287};
1288
1289#ifdef CONFIG_SYSCTL
1290static struct ctl_table kern_reboot_table[] = {
1291 {
1292 .procname = "poweroff_cmd",
1293 .data = &poweroff_cmd,
1294 .maxlen = POWEROFF_CMD_PATH_LEN,
1295 .mode = 0644,
1296 .proc_handler = proc_dostring,
1297 },
1298 {
1299 .procname = "ctrl-alt-del",
1300 .data = &C_A_D,
1301 .maxlen = sizeof(int),
1302 .mode = 0644,
1303 .proc_handler = proc_dointvec,
1304 },
1305};
1306
1307static void __init kernel_reboot_sysctls_init(void)
1308{
1309 register_sysctl_init("kernel", kern_reboot_table);
1310}
1311#else
1312#define kernel_reboot_sysctls_init() do { } while (0)
1313#endif /* CONFIG_SYSCTL */
1314
1315static const struct attribute_group reboot_attr_group = {
1316 .attrs = reboot_attrs,
1317};
1318
1319static int __init reboot_ksysfs_init(void)
1320{
1321 struct kobject *reboot_kobj;
1322 int ret;
1323
1324 reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);
1325 if (!reboot_kobj)
1326 return -ENOMEM;
1327
1328 ret = sysfs_create_group(reboot_kobj, &reboot_attr_group);
1329 if (ret) {
1330 kobject_put(reboot_kobj);
1331 return ret;
1332 }
1333
1334 kernel_reboot_sysctls_init();
1335
1336 return 0;
1337}
1338late_initcall(reboot_ksysfs_init);
1339
1340#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