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1/*
2 * linux/kernel/reboot.c
3 *
4 * Copyright (C) 2013 Linus Torvalds
5 */
6
7#define pr_fmt(fmt) "reboot: " fmt
8
9#include <linux/ctype.h>
10#include <linux/export.h>
11#include <linux/kexec.h>
12#include <linux/kmod.h>
13#include <linux/kmsg_dump.h>
14#include <linux/reboot.h>
15#include <linux/suspend.h>
16#include <linux/syscalls.h>
17#include <linux/syscore_ops.h>
18#include <linux/uaccess.h>
19
20/*
21 * this indicates whether you can reboot with ctrl-alt-del: the default is yes
22 */
23
24int C_A_D = 1;
25struct pid *cad_pid;
26EXPORT_SYMBOL(cad_pid);
27
28#if defined(CONFIG_ARM) || defined(CONFIG_UNICORE32)
29#define DEFAULT_REBOOT_MODE = REBOOT_HARD
30#else
31#define DEFAULT_REBOOT_MODE
32#endif
33enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
34
35/*
36 * This variable is used privately to keep track of whether or not
37 * reboot_type is still set to its default value (i.e., reboot= hasn't
38 * been set on the command line). This is needed so that we can
39 * suppress DMI scanning for reboot quirks. Without it, it's
40 * impossible to override a faulty reboot quirk without recompiling.
41 */
42int reboot_default = 1;
43int reboot_cpu;
44enum reboot_type reboot_type = BOOT_ACPI;
45int reboot_force;
46
47/*
48 * If set, this is used for preparing the system to power off.
49 */
50
51void (*pm_power_off_prepare)(void);
52
53/**
54 * emergency_restart - reboot the system
55 *
56 * Without shutting down any hardware or taking any locks
57 * reboot the system. This is called when we know we are in
58 * trouble so this is our best effort to reboot. This is
59 * safe to call in interrupt context.
60 */
61void emergency_restart(void)
62{
63 kmsg_dump(KMSG_DUMP_EMERG);
64 machine_emergency_restart();
65}
66EXPORT_SYMBOL_GPL(emergency_restart);
67
68void kernel_restart_prepare(char *cmd)
69{
70 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
71 system_state = SYSTEM_RESTART;
72 usermodehelper_disable();
73 device_shutdown();
74}
75
76/**
77 * register_reboot_notifier - Register function to be called at reboot time
78 * @nb: Info about notifier function to be called
79 *
80 * Registers a function with the list of functions
81 * to be called at reboot time.
82 *
83 * Currently always returns zero, as blocking_notifier_chain_register()
84 * always returns zero.
85 */
86int register_reboot_notifier(struct notifier_block *nb)
87{
88 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
89}
90EXPORT_SYMBOL(register_reboot_notifier);
91
92/**
93 * unregister_reboot_notifier - Unregister previously registered reboot notifier
94 * @nb: Hook to be unregistered
95 *
96 * Unregisters a previously registered reboot
97 * notifier function.
98 *
99 * Returns zero on success, or %-ENOENT on failure.
100 */
101int unregister_reboot_notifier(struct notifier_block *nb)
102{
103 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
104}
105EXPORT_SYMBOL(unregister_reboot_notifier);
106
107/*
108 * Notifier list for kernel code which wants to be called
109 * to restart the system.
110 */
111static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
112
113/**
114 * register_restart_handler - Register function to be called to reset
115 * the system
116 * @nb: Info about handler function to be called
117 * @nb->priority: Handler priority. Handlers should follow the
118 * following guidelines for setting priorities.
119 * 0: Restart handler of last resort,
120 * with limited restart capabilities
121 * 128: Default restart handler; use if no other
122 * restart handler is expected to be available,
123 * and/or if restart functionality is
124 * sufficient to restart the entire system
125 * 255: Highest priority restart handler, will
126 * preempt all other restart handlers
127 *
128 * Registers a function with code to be called to restart the
129 * system.
130 *
131 * Registered functions will be called from machine_restart as last
132 * step of the restart sequence (if the architecture specific
133 * machine_restart function calls do_kernel_restart - see below
134 * for details).
135 * Registered functions are expected to restart the system immediately.
136 * If more than one function is registered, the restart handler priority
137 * selects which function will be called first.
138 *
139 * Restart handlers are expected to be registered from non-architecture
140 * code, typically from drivers. A typical use case would be a system
141 * where restart functionality is provided through a watchdog. Multiple
142 * restart handlers may exist; for example, one restart handler might
143 * restart the entire system, while another only restarts the CPU.
144 * In such cases, the restart handler which only restarts part of the
145 * hardware is expected to register with low priority to ensure that
146 * it only runs if no other means to restart the system is available.
147 *
148 * Currently always returns zero, as atomic_notifier_chain_register()
149 * always returns zero.
150 */
151int register_restart_handler(struct notifier_block *nb)
152{
153 return atomic_notifier_chain_register(&restart_handler_list, nb);
154}
155EXPORT_SYMBOL(register_restart_handler);
156
157/**
158 * unregister_restart_handler - Unregister previously registered
159 * restart handler
160 * @nb: Hook to be unregistered
161 *
162 * Unregisters a previously registered restart handler function.
163 *
164 * Returns zero on success, or %-ENOENT on failure.
165 */
166int unregister_restart_handler(struct notifier_block *nb)
167{
168 return atomic_notifier_chain_unregister(&restart_handler_list, nb);
169}
170EXPORT_SYMBOL(unregister_restart_handler);
171
172/**
173 * do_kernel_restart - Execute kernel restart handler call chain
174 *
175 * Calls functions registered with register_restart_handler.
176 *
177 * Expected to be called from machine_restart as last step of the restart
178 * sequence.
179 *
180 * Restarts the system immediately if a restart handler function has been
181 * registered. Otherwise does nothing.
182 */
183void do_kernel_restart(char *cmd)
184{
185 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
186}
187
188void migrate_to_reboot_cpu(void)
189{
190 /* The boot cpu is always logical cpu 0 */
191 int cpu = reboot_cpu;
192
193 cpu_hotplug_disable();
194
195 /* Make certain the cpu I'm about to reboot on is online */
196 if (!cpu_online(cpu))
197 cpu = cpumask_first(cpu_online_mask);
198
199 /* Prevent races with other tasks migrating this task */
200 current->flags |= PF_NO_SETAFFINITY;
201
202 /* Make certain I only run on the appropriate processor */
203 set_cpus_allowed_ptr(current, cpumask_of(cpu));
204}
205
206/**
207 * kernel_restart - reboot the system
208 * @cmd: pointer to buffer containing command to execute for restart
209 * or %NULL
210 *
211 * Shutdown everything and perform a clean reboot.
212 * This is not safe to call in interrupt context.
213 */
214void kernel_restart(char *cmd)
215{
216 kernel_restart_prepare(cmd);
217 migrate_to_reboot_cpu();
218 syscore_shutdown();
219 if (!cmd)
220 pr_emerg("Restarting system\n");
221 else
222 pr_emerg("Restarting system with command '%s'\n", cmd);
223 kmsg_dump(KMSG_DUMP_RESTART);
224 machine_restart(cmd);
225}
226EXPORT_SYMBOL_GPL(kernel_restart);
227
228static void kernel_shutdown_prepare(enum system_states state)
229{
230 blocking_notifier_call_chain(&reboot_notifier_list,
231 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
232 system_state = state;
233 usermodehelper_disable();
234 device_shutdown();
235}
236/**
237 * kernel_halt - halt the system
238 *
239 * Shutdown everything and perform a clean system halt.
240 */
241void kernel_halt(void)
242{
243 kernel_shutdown_prepare(SYSTEM_HALT);
244 migrate_to_reboot_cpu();
245 syscore_shutdown();
246 pr_emerg("System halted\n");
247 kmsg_dump(KMSG_DUMP_HALT);
248 machine_halt();
249}
250EXPORT_SYMBOL_GPL(kernel_halt);
251
252/**
253 * kernel_power_off - power_off the system
254 *
255 * Shutdown everything and perform a clean system power_off.
256 */
257void kernel_power_off(void)
258{
259 kernel_shutdown_prepare(SYSTEM_POWER_OFF);
260 if (pm_power_off_prepare)
261 pm_power_off_prepare();
262 migrate_to_reboot_cpu();
263 syscore_shutdown();
264 pr_emerg("Power down\n");
265 kmsg_dump(KMSG_DUMP_POWEROFF);
266 machine_power_off();
267}
268EXPORT_SYMBOL_GPL(kernel_power_off);
269
270static DEFINE_MUTEX(reboot_mutex);
271
272/*
273 * Reboot system call: for obvious reasons only root may call it,
274 * and even root needs to set up some magic numbers in the registers
275 * so that some mistake won't make this reboot the whole machine.
276 * You can also set the meaning of the ctrl-alt-del-key here.
277 *
278 * reboot doesn't sync: do that yourself before calling this.
279 */
280SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
281 void __user *, arg)
282{
283 struct pid_namespace *pid_ns = task_active_pid_ns(current);
284 char buffer[256];
285 int ret = 0;
286
287 /* We only trust the superuser with rebooting the system. */
288 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
289 return -EPERM;
290
291 /* For safety, we require "magic" arguments. */
292 if (magic1 != LINUX_REBOOT_MAGIC1 ||
293 (magic2 != LINUX_REBOOT_MAGIC2 &&
294 magic2 != LINUX_REBOOT_MAGIC2A &&
295 magic2 != LINUX_REBOOT_MAGIC2B &&
296 magic2 != LINUX_REBOOT_MAGIC2C))
297 return -EINVAL;
298
299 /*
300 * If pid namespaces are enabled and the current task is in a child
301 * pid_namespace, the command is handled by reboot_pid_ns() which will
302 * call do_exit().
303 */
304 ret = reboot_pid_ns(pid_ns, cmd);
305 if (ret)
306 return ret;
307
308 /* Instead of trying to make the power_off code look like
309 * halt when pm_power_off is not set do it the easy way.
310 */
311 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
312 cmd = LINUX_REBOOT_CMD_HALT;
313
314 mutex_lock(&reboot_mutex);
315 switch (cmd) {
316 case LINUX_REBOOT_CMD_RESTART:
317 kernel_restart(NULL);
318 break;
319
320 case LINUX_REBOOT_CMD_CAD_ON:
321 C_A_D = 1;
322 break;
323
324 case LINUX_REBOOT_CMD_CAD_OFF:
325 C_A_D = 0;
326 break;
327
328 case LINUX_REBOOT_CMD_HALT:
329 kernel_halt();
330 do_exit(0);
331 panic("cannot halt");
332
333 case LINUX_REBOOT_CMD_POWER_OFF:
334 kernel_power_off();
335 do_exit(0);
336 break;
337
338 case LINUX_REBOOT_CMD_RESTART2:
339 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
340 if (ret < 0) {
341 ret = -EFAULT;
342 break;
343 }
344 buffer[sizeof(buffer) - 1] = '\0';
345
346 kernel_restart(buffer);
347 break;
348
349#ifdef CONFIG_KEXEC_CORE
350 case LINUX_REBOOT_CMD_KEXEC:
351 ret = kernel_kexec();
352 break;
353#endif
354
355#ifdef CONFIG_HIBERNATION
356 case LINUX_REBOOT_CMD_SW_SUSPEND:
357 ret = hibernate();
358 break;
359#endif
360
361 default:
362 ret = -EINVAL;
363 break;
364 }
365 mutex_unlock(&reboot_mutex);
366 return ret;
367}
368
369static void deferred_cad(struct work_struct *dummy)
370{
371 kernel_restart(NULL);
372}
373
374/*
375 * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
376 * As it's called within an interrupt, it may NOT sync: the only choice
377 * is whether to reboot at once, or just ignore the ctrl-alt-del.
378 */
379void ctrl_alt_del(void)
380{
381 static DECLARE_WORK(cad_work, deferred_cad);
382
383 if (C_A_D)
384 schedule_work(&cad_work);
385 else
386 kill_cad_pid(SIGINT, 1);
387}
388
389char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
390static const char reboot_cmd[] = "/sbin/reboot";
391
392static int run_cmd(const char *cmd)
393{
394 char **argv;
395 static char *envp[] = {
396 "HOME=/",
397 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
398 NULL
399 };
400 int ret;
401 argv = argv_split(GFP_KERNEL, cmd, NULL);
402 if (argv) {
403 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
404 argv_free(argv);
405 } else {
406 ret = -ENOMEM;
407 }
408
409 return ret;
410}
411
412static int __orderly_reboot(void)
413{
414 int ret;
415
416 ret = run_cmd(reboot_cmd);
417
418 if (ret) {
419 pr_warn("Failed to start orderly reboot: forcing the issue\n");
420 emergency_sync();
421 kernel_restart(NULL);
422 }
423
424 return ret;
425}
426
427static int __orderly_poweroff(bool force)
428{
429 int ret;
430
431 ret = run_cmd(poweroff_cmd);
432
433 if (ret && force) {
434 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
435
436 /*
437 * I guess this should try to kick off some daemon to sync and
438 * poweroff asap. Or not even bother syncing if we're doing an
439 * emergency shutdown?
440 */
441 emergency_sync();
442 kernel_power_off();
443 }
444
445 return ret;
446}
447
448static bool poweroff_force;
449
450static void poweroff_work_func(struct work_struct *work)
451{
452 __orderly_poweroff(poweroff_force);
453}
454
455static DECLARE_WORK(poweroff_work, poweroff_work_func);
456
457/**
458 * orderly_poweroff - Trigger an orderly system poweroff
459 * @force: force poweroff if command execution fails
460 *
461 * This may be called from any context to trigger a system shutdown.
462 * If the orderly shutdown fails, it will force an immediate shutdown.
463 */
464void orderly_poweroff(bool force)
465{
466 if (force) /* do not override the pending "true" */
467 poweroff_force = true;
468 schedule_work(&poweroff_work);
469}
470EXPORT_SYMBOL_GPL(orderly_poweroff);
471
472static void reboot_work_func(struct work_struct *work)
473{
474 __orderly_reboot();
475}
476
477static DECLARE_WORK(reboot_work, reboot_work_func);
478
479/**
480 * orderly_reboot - Trigger an orderly system reboot
481 *
482 * This may be called from any context to trigger a system reboot.
483 * If the orderly reboot fails, it will force an immediate reboot.
484 */
485void orderly_reboot(void)
486{
487 schedule_work(&reboot_work);
488}
489EXPORT_SYMBOL_GPL(orderly_reboot);
490
491static int __init reboot_setup(char *str)
492{
493 for (;;) {
494 /*
495 * Having anything passed on the command line via
496 * reboot= will cause us to disable DMI checking
497 * below.
498 */
499 reboot_default = 0;
500
501 switch (*str) {
502 case 'w':
503 reboot_mode = REBOOT_WARM;
504 break;
505
506 case 'c':
507 reboot_mode = REBOOT_COLD;
508 break;
509
510 case 'h':
511 reboot_mode = REBOOT_HARD;
512 break;
513
514 case 's':
515 {
516 int rc;
517
518 if (isdigit(*(str+1))) {
519 rc = kstrtoint(str+1, 0, &reboot_cpu);
520 if (rc)
521 return rc;
522 } else if (str[1] == 'm' && str[2] == 'p' &&
523 isdigit(*(str+3))) {
524 rc = kstrtoint(str+3, 0, &reboot_cpu);
525 if (rc)
526 return rc;
527 } else
528 reboot_mode = REBOOT_SOFT;
529 break;
530 }
531 case 'g':
532 reboot_mode = REBOOT_GPIO;
533 break;
534
535 case 'b':
536 case 'a':
537 case 'k':
538 case 't':
539 case 'e':
540 case 'p':
541 reboot_type = *str;
542 break;
543
544 case 'f':
545 reboot_force = 1;
546 break;
547 }
548
549 str = strchr(str, ',');
550 if (str)
551 str++;
552 else
553 break;
554 }
555 return 1;
556}
557__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