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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/ctype.h>
11#include <linux/export.h>
12#include <linux/kexec.h>
13#include <linux/kmod.h>
14#include <linux/kmsg_dump.h>
15#include <linux/reboot.h>
16#include <linux/suspend.h>
17#include <linux/syscalls.h>
18#include <linux/syscore_ops.h>
19#include <linux/uaccess.h>
20
21/*
22 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
23 */
24
25int C_A_D = 1;
26struct pid *cad_pid;
27EXPORT_SYMBOL(cad_pid);
28
29#if defined(CONFIG_ARM) || defined(CONFIG_UNICORE32)
30#define DEFAULT_REBOOT_MODE = REBOOT_HARD
31#else
32#define DEFAULT_REBOOT_MODE
33#endif
34enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
35enum reboot_mode panic_reboot_mode = REBOOT_UNDEFINED;
36
37/*
38 * This variable is used privately to keep track of whether or not
39 * reboot_type is still set to its default value (i.e., reboot= hasn't
40 * been set on the command line). This is needed so that we can
41 * suppress DMI scanning for reboot quirks. Without it, it's
42 * impossible to override a faulty reboot quirk without recompiling.
43 */
44int reboot_default = 1;
45int reboot_cpu;
46enum reboot_type reboot_type = BOOT_ACPI;
47int reboot_force;
48
49/*
50 * If set, this is used for preparing the system to power off.
51 */
52
53void (*pm_power_off_prepare)(void);
54EXPORT_SYMBOL_GPL(pm_power_off_prepare);
55
56/**
57 * emergency_restart - reboot the system
58 *
59 * Without shutting down any hardware or taking any locks
60 * reboot the system. This is called when we know we are in
61 * trouble so this is our best effort to reboot. This is
62 * safe to call in interrupt context.
63 */
64void emergency_restart(void)
65{
66 kmsg_dump(KMSG_DUMP_EMERG);
67 machine_emergency_restart();
68}
69EXPORT_SYMBOL_GPL(emergency_restart);
70
71void kernel_restart_prepare(char *cmd)
72{
73 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
74 system_state = SYSTEM_RESTART;
75 usermodehelper_disable();
76 device_shutdown();
77}
78
79/**
80 * register_reboot_notifier - Register function to be called at reboot time
81 * @nb: Info about notifier function to be called
82 *
83 * Registers a function with the list of functions
84 * to be called at reboot time.
85 *
86 * Currently always returns zero, as blocking_notifier_chain_register()
87 * always returns zero.
88 */
89int register_reboot_notifier(struct notifier_block *nb)
90{
91 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
92}
93EXPORT_SYMBOL(register_reboot_notifier);
94
95/**
96 * unregister_reboot_notifier - Unregister previously registered reboot notifier
97 * @nb: Hook to be unregistered
98 *
99 * Unregisters a previously registered reboot
100 * notifier function.
101 *
102 * Returns zero on success, or %-ENOENT on failure.
103 */
104int unregister_reboot_notifier(struct notifier_block *nb)
105{
106 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
107}
108EXPORT_SYMBOL(unregister_reboot_notifier);
109
110static void devm_unregister_reboot_notifier(struct device *dev, void *res)
111{
112 WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
113}
114
115int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
116{
117 struct notifier_block **rcnb;
118 int ret;
119
120 rcnb = devres_alloc(devm_unregister_reboot_notifier,
121 sizeof(*rcnb), GFP_KERNEL);
122 if (!rcnb)
123 return -ENOMEM;
124
125 ret = register_reboot_notifier(nb);
126 if (!ret) {
127 *rcnb = nb;
128 devres_add(dev, rcnb);
129 } else {
130 devres_free(rcnb);
131 }
132
133 return ret;
134}
135EXPORT_SYMBOL(devm_register_reboot_notifier);
136
137/*
138 * Notifier list for kernel code which wants to be called
139 * to restart the system.
140 */
141static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
142
143/**
144 * register_restart_handler - Register function to be called to reset
145 * the system
146 * @nb: Info about handler function to be called
147 * @nb->priority: Handler priority. Handlers should follow the
148 * following guidelines for setting priorities.
149 * 0: Restart handler of last resort,
150 * with limited restart capabilities
151 * 128: Default restart handler; use if no other
152 * restart handler is expected to be available,
153 * and/or if restart functionality is
154 * sufficient to restart the entire system
155 * 255: Highest priority restart handler, will
156 * preempt all other restart handlers
157 *
158 * Registers a function with code to be called to restart the
159 * system.
160 *
161 * Registered functions will be called from machine_restart as last
162 * step of the restart sequence (if the architecture specific
163 * machine_restart function calls do_kernel_restart - see below
164 * for details).
165 * Registered functions are expected to restart the system immediately.
166 * If more than one function is registered, the restart handler priority
167 * selects which function will be called first.
168 *
169 * Restart handlers are expected to be registered from non-architecture
170 * code, typically from drivers. A typical use case would be a system
171 * where restart functionality is provided through a watchdog. Multiple
172 * restart handlers may exist; for example, one restart handler might
173 * restart the entire system, while another only restarts the CPU.
174 * In such cases, the restart handler which only restarts part of the
175 * hardware is expected to register with low priority to ensure that
176 * it only runs if no other means to restart the system is available.
177 *
178 * Currently always returns zero, as atomic_notifier_chain_register()
179 * always returns zero.
180 */
181int register_restart_handler(struct notifier_block *nb)
182{
183 return atomic_notifier_chain_register(&restart_handler_list, nb);
184}
185EXPORT_SYMBOL(register_restart_handler);
186
187/**
188 * unregister_restart_handler - Unregister previously registered
189 * restart handler
190 * @nb: Hook to be unregistered
191 *
192 * Unregisters a previously registered restart handler function.
193 *
194 * Returns zero on success, or %-ENOENT on failure.
195 */
196int unregister_restart_handler(struct notifier_block *nb)
197{
198 return atomic_notifier_chain_unregister(&restart_handler_list, nb);
199}
200EXPORT_SYMBOL(unregister_restart_handler);
201
202/**
203 * do_kernel_restart - Execute kernel restart handler call chain
204 *
205 * Calls functions registered with register_restart_handler.
206 *
207 * Expected to be called from machine_restart as last step of the restart
208 * sequence.
209 *
210 * Restarts the system immediately if a restart handler function has been
211 * registered. Otherwise does nothing.
212 */
213void do_kernel_restart(char *cmd)
214{
215 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
216}
217
218void migrate_to_reboot_cpu(void)
219{
220 /* The boot cpu is always logical cpu 0 */
221 int cpu = reboot_cpu;
222
223 cpu_hotplug_disable();
224
225 /* Make certain the cpu I'm about to reboot on is online */
226 if (!cpu_online(cpu))
227 cpu = cpumask_first(cpu_online_mask);
228
229 /* Prevent races with other tasks migrating this task */
230 current->flags |= PF_NO_SETAFFINITY;
231
232 /* Make certain I only run on the appropriate processor */
233 set_cpus_allowed_ptr(current, cpumask_of(cpu));
234}
235
236/**
237 * kernel_restart - reboot the system
238 * @cmd: pointer to buffer containing command to execute for restart
239 * or %NULL
240 *
241 * Shutdown everything and perform a clean reboot.
242 * This is not safe to call in interrupt context.
243 */
244void kernel_restart(char *cmd)
245{
246 kernel_restart_prepare(cmd);
247 migrate_to_reboot_cpu();
248 syscore_shutdown();
249 if (!cmd)
250 pr_emerg("Restarting system\n");
251 else
252 pr_emerg("Restarting system with command '%s'\n", cmd);
253 kmsg_dump(KMSG_DUMP_RESTART);
254 machine_restart(cmd);
255}
256EXPORT_SYMBOL_GPL(kernel_restart);
257
258static void kernel_shutdown_prepare(enum system_states state)
259{
260 blocking_notifier_call_chain(&reboot_notifier_list,
261 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
262 system_state = state;
263 usermodehelper_disable();
264 device_shutdown();
265}
266/**
267 * kernel_halt - halt the system
268 *
269 * Shutdown everything and perform a clean system halt.
270 */
271void kernel_halt(void)
272{
273 kernel_shutdown_prepare(SYSTEM_HALT);
274 migrate_to_reboot_cpu();
275 syscore_shutdown();
276 pr_emerg("System halted\n");
277 kmsg_dump(KMSG_DUMP_HALT);
278 machine_halt();
279}
280EXPORT_SYMBOL_GPL(kernel_halt);
281
282/**
283 * kernel_power_off - power_off the system
284 *
285 * Shutdown everything and perform a clean system power_off.
286 */
287void kernel_power_off(void)
288{
289 kernel_shutdown_prepare(SYSTEM_POWER_OFF);
290 if (pm_power_off_prepare)
291 pm_power_off_prepare();
292 migrate_to_reboot_cpu();
293 syscore_shutdown();
294 pr_emerg("Power down\n");
295 kmsg_dump(KMSG_DUMP_POWEROFF);
296 machine_power_off();
297}
298EXPORT_SYMBOL_GPL(kernel_power_off);
299
300DEFINE_MUTEX(system_transition_mutex);
301
302/*
303 * Reboot system call: for obvious reasons only root may call it,
304 * and even root needs to set up some magic numbers in the registers
305 * so that some mistake won't make this reboot the whole machine.
306 * You can also set the meaning of the ctrl-alt-del-key here.
307 *
308 * reboot doesn't sync: do that yourself before calling this.
309 */
310SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
311 void __user *, arg)
312{
313 struct pid_namespace *pid_ns = task_active_pid_ns(current);
314 char buffer[256];
315 int ret = 0;
316
317 /* We only trust the superuser with rebooting the system. */
318 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
319 return -EPERM;
320
321 /* For safety, we require "magic" arguments. */
322 if (magic1 != LINUX_REBOOT_MAGIC1 ||
323 (magic2 != LINUX_REBOOT_MAGIC2 &&
324 magic2 != LINUX_REBOOT_MAGIC2A &&
325 magic2 != LINUX_REBOOT_MAGIC2B &&
326 magic2 != LINUX_REBOOT_MAGIC2C))
327 return -EINVAL;
328
329 /*
330 * If pid namespaces are enabled and the current task is in a child
331 * pid_namespace, the command is handled by reboot_pid_ns() which will
332 * call do_exit().
333 */
334 ret = reboot_pid_ns(pid_ns, cmd);
335 if (ret)
336 return ret;
337
338 /* Instead of trying to make the power_off code look like
339 * halt when pm_power_off is not set do it the easy way.
340 */
341 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
342 cmd = LINUX_REBOOT_CMD_HALT;
343
344 mutex_lock(&system_transition_mutex);
345 switch (cmd) {
346 case LINUX_REBOOT_CMD_RESTART:
347 kernel_restart(NULL);
348 break;
349
350 case LINUX_REBOOT_CMD_CAD_ON:
351 C_A_D = 1;
352 break;
353
354 case LINUX_REBOOT_CMD_CAD_OFF:
355 C_A_D = 0;
356 break;
357
358 case LINUX_REBOOT_CMD_HALT:
359 kernel_halt();
360 do_exit(0);
361 panic("cannot halt");
362
363 case LINUX_REBOOT_CMD_POWER_OFF:
364 kernel_power_off();
365 do_exit(0);
366 break;
367
368 case LINUX_REBOOT_CMD_RESTART2:
369 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
370 if (ret < 0) {
371 ret = -EFAULT;
372 break;
373 }
374 buffer[sizeof(buffer) - 1] = '\0';
375
376 kernel_restart(buffer);
377 break;
378
379#ifdef CONFIG_KEXEC_CORE
380 case LINUX_REBOOT_CMD_KEXEC:
381 ret = kernel_kexec();
382 break;
383#endif
384
385#ifdef CONFIG_HIBERNATION
386 case LINUX_REBOOT_CMD_SW_SUSPEND:
387 ret = hibernate();
388 break;
389#endif
390
391 default:
392 ret = -EINVAL;
393 break;
394 }
395 mutex_unlock(&system_transition_mutex);
396 return ret;
397}
398
399static void deferred_cad(struct work_struct *dummy)
400{
401 kernel_restart(NULL);
402}
403
404/*
405 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
406 * As it's called within an interrupt, it may NOT sync: the only choice
407 * is whether to reboot at once, or just ignore the ctrl-alt-del.
408 */
409void ctrl_alt_del(void)
410{
411 static DECLARE_WORK(cad_work, deferred_cad);
412
413 if (C_A_D)
414 schedule_work(&cad_work);
415 else
416 kill_cad_pid(SIGINT, 1);
417}
418
419char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
420static const char reboot_cmd[] = "/sbin/reboot";
421
422static int run_cmd(const char *cmd)
423{
424 char **argv;
425 static char *envp[] = {
426 "HOME=/",
427 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
428 NULL
429 };
430 int ret;
431 argv = argv_split(GFP_KERNEL, cmd, NULL);
432 if (argv) {
433 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
434 argv_free(argv);
435 } else {
436 ret = -ENOMEM;
437 }
438
439 return ret;
440}
441
442static int __orderly_reboot(void)
443{
444 int ret;
445
446 ret = run_cmd(reboot_cmd);
447
448 if (ret) {
449 pr_warn("Failed to start orderly reboot: forcing the issue\n");
450 emergency_sync();
451 kernel_restart(NULL);
452 }
453
454 return ret;
455}
456
457static int __orderly_poweroff(bool force)
458{
459 int ret;
460
461 ret = run_cmd(poweroff_cmd);
462
463 if (ret && force) {
464 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
465
466 /*
467 * I guess this should try to kick off some daemon to sync and
468 * poweroff asap. Or not even bother syncing if we're doing an
469 * emergency shutdown?
470 */
471 emergency_sync();
472 kernel_power_off();
473 }
474
475 return ret;
476}
477
478static bool poweroff_force;
479
480static void poweroff_work_func(struct work_struct *work)
481{
482 __orderly_poweroff(poweroff_force);
483}
484
485static DECLARE_WORK(poweroff_work, poweroff_work_func);
486
487/**
488 * orderly_poweroff - Trigger an orderly system poweroff
489 * @force: force poweroff if command execution fails
490 *
491 * This may be called from any context to trigger a system shutdown.
492 * If the orderly shutdown fails, it will force an immediate shutdown.
493 */
494void orderly_poweroff(bool force)
495{
496 if (force) /* do not override the pending "true" */
497 poweroff_force = true;
498 schedule_work(&poweroff_work);
499}
500EXPORT_SYMBOL_GPL(orderly_poweroff);
501
502static void reboot_work_func(struct work_struct *work)
503{
504 __orderly_reboot();
505}
506
507static DECLARE_WORK(reboot_work, reboot_work_func);
508
509/**
510 * orderly_reboot - Trigger an orderly system reboot
511 *
512 * This may be called from any context to trigger a system reboot.
513 * If the orderly reboot fails, it will force an immediate reboot.
514 */
515void orderly_reboot(void)
516{
517 schedule_work(&reboot_work);
518}
519EXPORT_SYMBOL_GPL(orderly_reboot);
520
521static int __init reboot_setup(char *str)
522{
523 for (;;) {
524 enum reboot_mode *mode;
525
526 /*
527 * Having anything passed on the command line via
528 * reboot= will cause us to disable DMI checking
529 * below.
530 */
531 reboot_default = 0;
532
533 if (!strncmp(str, "panic_", 6)) {
534 mode = &panic_reboot_mode;
535 str += 6;
536 } else {
537 mode = &reboot_mode;
538 }
539
540 switch (*str) {
541 case 'w':
542 *mode = REBOOT_WARM;
543 break;
544
545 case 'c':
546 *mode = REBOOT_COLD;
547 break;
548
549 case 'h':
550 *mode = REBOOT_HARD;
551 break;
552
553 case 's':
554 {
555 int rc;
556
557 if (isdigit(*(str+1))) {
558 rc = kstrtoint(str+1, 0, &reboot_cpu);
559 if (rc)
560 return rc;
561 } else if (str[1] == 'm' && str[2] == 'p' &&
562 isdigit(*(str+3))) {
563 rc = kstrtoint(str+3, 0, &reboot_cpu);
564 if (rc)
565 return rc;
566 } else
567 *mode = REBOOT_SOFT;
568 break;
569 }
570 case 'g':
571 *mode = REBOOT_GPIO;
572 break;
573
574 case 'b':
575 case 'a':
576 case 'k':
577 case 't':
578 case 'e':
579 case 'p':
580 reboot_type = *str;
581 break;
582
583 case 'f':
584 reboot_force = 1;
585 break;
586 }
587
588 str = strchr(str, ',');
589 if (str)
590 str++;
591 else
592 break;
593 }
594 return 1;
595}
596__setup("reboot=", reboot_setup);
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