Commit | Line | Data |
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15d94b82 RH |
1 | /* |
2 | * linux/kernel/reboot.c | |
3 | * | |
4 | * Copyright (C) 2013 Linus Torvalds | |
5 | */ | |
6 | ||
972ee83d RH |
7 | #define pr_fmt(fmt) "reboot: " fmt |
8 | ||
1b3a5d02 | 9 | #include <linux/ctype.h> |
15d94b82 RH |
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 | ||
24 | int C_A_D = 1; | |
25 | struct pid *cad_pid; | |
26 | EXPORT_SYMBOL(cad_pid); | |
27 | ||
1b3a5d02 RH |
28 | #if defined(CONFIG_ARM) || defined(CONFIG_UNICORE32) |
29 | #define DEFAULT_REBOOT_MODE = REBOOT_HARD | |
30 | #else | |
31 | #define DEFAULT_REBOOT_MODE | |
32 | #endif | |
33 | enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE; | |
34 | ||
e2f0b88e CL |
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 | */ | |
42 | int reboot_default = 1; | |
1b3a5d02 RH |
43 | int reboot_cpu; |
44 | enum reboot_type reboot_type = BOOT_ACPI; | |
45 | int reboot_force; | |
46 | ||
15d94b82 RH |
47 | /* |
48 | * If set, this is used for preparing the system to power off. | |
49 | */ | |
50 | ||
51 | void (*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 | */ | |
61 | void emergency_restart(void) | |
62 | { | |
63 | kmsg_dump(KMSG_DUMP_EMERG); | |
64 | machine_emergency_restart(); | |
65 | } | |
66 | EXPORT_SYMBOL_GPL(emergency_restart); | |
67 | ||
68 | void 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 | */ | |
86 | int register_reboot_notifier(struct notifier_block *nb) | |
87 | { | |
88 | return blocking_notifier_chain_register(&reboot_notifier_list, nb); | |
89 | } | |
90 | EXPORT_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 | */ | |
101 | int unregister_reboot_notifier(struct notifier_block *nb) | |
102 | { | |
103 | return blocking_notifier_chain_unregister(&reboot_notifier_list, nb); | |
104 | } | |
105 | EXPORT_SYMBOL(unregister_reboot_notifier); | |
106 | ||
b63adb97 GR |
107 | /* |
108 | * Notifier list for kernel code which wants to be called | |
109 | * to restart the system. | |
110 | */ | |
0b1ac11f | 111 | ATOMIC_NOTIFIER_HEAD(restart_handler_list); |
b63adb97 GR |
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 | */ | |
151 | int register_restart_handler(struct notifier_block *nb) | |
152 | { | |
153 | return atomic_notifier_chain_register(&restart_handler_list, nb); | |
154 | } | |
155 | EXPORT_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 | */ | |
166 | int unregister_restart_handler(struct notifier_block *nb) | |
167 | { | |
168 | return atomic_notifier_chain_unregister(&restart_handler_list, nb); | |
169 | } | |
170 | EXPORT_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 | */ | |
183 | void do_kernel_restart(char *cmd) | |
184 | { | |
185 | atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd); | |
186 | } | |
187 | ||
c97102ba | 188 | void migrate_to_reboot_cpu(void) |
15d94b82 RH |
189 | { |
190 | /* The boot cpu is always logical cpu 0 */ | |
1b3a5d02 | 191 | int cpu = reboot_cpu; |
15d94b82 RH |
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 | */ | |
214 | void kernel_restart(char *cmd) | |
215 | { | |
216 | kernel_restart_prepare(cmd); | |
217 | migrate_to_reboot_cpu(); | |
218 | syscore_shutdown(); | |
219 | if (!cmd) | |
972ee83d | 220 | pr_emerg("Restarting system\n"); |
15d94b82 | 221 | else |
972ee83d | 222 | pr_emerg("Restarting system with command '%s'\n", cmd); |
4f62450e | 223 | printk(KERN_EMERG "Current task:%s(%d) Parent task:%s(%d)\n", |
224 | current->comm, current->pid, | |
225 | current->real_parent->comm, | |
226 | current->real_parent->pid); | |
15d94b82 RH |
227 | kmsg_dump(KMSG_DUMP_RESTART); |
228 | machine_restart(cmd); | |
229 | } | |
230 | EXPORT_SYMBOL_GPL(kernel_restart); | |
231 | ||
232 | static void kernel_shutdown_prepare(enum system_states state) | |
233 | { | |
234 | blocking_notifier_call_chain(&reboot_notifier_list, | |
972ee83d | 235 | (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL); |
15d94b82 RH |
236 | system_state = state; |
237 | usermodehelper_disable(); | |
238 | device_shutdown(); | |
239 | } | |
240 | /** | |
241 | * kernel_halt - halt the system | |
242 | * | |
243 | * Shutdown everything and perform a clean system halt. | |
244 | */ | |
245 | void kernel_halt(void) | |
246 | { | |
247 | kernel_shutdown_prepare(SYSTEM_HALT); | |
248 | migrate_to_reboot_cpu(); | |
249 | syscore_shutdown(); | |
972ee83d | 250 | pr_emerg("System halted\n"); |
15d94b82 RH |
251 | kmsg_dump(KMSG_DUMP_HALT); |
252 | machine_halt(); | |
253 | } | |
15d94b82 RH |
254 | EXPORT_SYMBOL_GPL(kernel_halt); |
255 | ||
256 | /** | |
257 | * kernel_power_off - power_off the system | |
258 | * | |
259 | * Shutdown everything and perform a clean system power_off. | |
260 | */ | |
261 | void kernel_power_off(void) | |
262 | { | |
263 | kernel_shutdown_prepare(SYSTEM_POWER_OFF); | |
264 | if (pm_power_off_prepare) | |
265 | pm_power_off_prepare(); | |
266 | migrate_to_reboot_cpu(); | |
267 | syscore_shutdown(); | |
972ee83d | 268 | pr_emerg("Power down\n"); |
4f62450e | 269 | printk(KERN_EMERG "Current task:%s(%d) Parent task:%s(%d)\n", |
270 | current->comm, current->pid, | |
271 | current->real_parent->comm, | |
272 | current->real_parent->pid); | |
15d94b82 RH |
273 | kmsg_dump(KMSG_DUMP_POWEROFF); |
274 | machine_power_off(); | |
275 | } | |
276 | EXPORT_SYMBOL_GPL(kernel_power_off); | |
277 | ||
278 | static DEFINE_MUTEX(reboot_mutex); | |
279 | ||
280 | /* | |
281 | * Reboot system call: for obvious reasons only root may call it, | |
282 | * and even root needs to set up some magic numbers in the registers | |
283 | * so that some mistake won't make this reboot the whole machine. | |
284 | * You can also set the meaning of the ctrl-alt-del-key here. | |
285 | * | |
286 | * reboot doesn't sync: do that yourself before calling this. | |
287 | */ | |
288 | SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, | |
289 | void __user *, arg) | |
290 | { | |
291 | struct pid_namespace *pid_ns = task_active_pid_ns(current); | |
292 | char buffer[256]; | |
293 | int ret = 0; | |
294 | ||
295 | /* We only trust the superuser with rebooting the system. */ | |
296 | if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT)) | |
297 | return -EPERM; | |
298 | ||
299 | /* For safety, we require "magic" arguments. */ | |
300 | if (magic1 != LINUX_REBOOT_MAGIC1 || | |
972ee83d RH |
301 | (magic2 != LINUX_REBOOT_MAGIC2 && |
302 | magic2 != LINUX_REBOOT_MAGIC2A && | |
15d94b82 | 303 | magic2 != LINUX_REBOOT_MAGIC2B && |
972ee83d | 304 | magic2 != LINUX_REBOOT_MAGIC2C)) |
15d94b82 RH |
305 | return -EINVAL; |
306 | ||
307 | /* | |
308 | * If pid namespaces are enabled and the current task is in a child | |
309 | * pid_namespace, the command is handled by reboot_pid_ns() which will | |
310 | * call do_exit(). | |
311 | */ | |
312 | ret = reboot_pid_ns(pid_ns, cmd); | |
313 | if (ret) | |
314 | return ret; | |
315 | ||
316 | /* Instead of trying to make the power_off code look like | |
317 | * halt when pm_power_off is not set do it the easy way. | |
318 | */ | |
319 | if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off) | |
320 | cmd = LINUX_REBOOT_CMD_HALT; | |
321 | ||
322 | mutex_lock(&reboot_mutex); | |
323 | switch (cmd) { | |
324 | case LINUX_REBOOT_CMD_RESTART: | |
325 | kernel_restart(NULL); | |
326 | break; | |
327 | ||
328 | case LINUX_REBOOT_CMD_CAD_ON: | |
329 | C_A_D = 1; | |
330 | break; | |
331 | ||
332 | case LINUX_REBOOT_CMD_CAD_OFF: | |
333 | C_A_D = 0; | |
334 | break; | |
335 | ||
336 | case LINUX_REBOOT_CMD_HALT: | |
337 | kernel_halt(); | |
338 | do_exit(0); | |
339 | panic("cannot halt"); | |
340 | ||
341 | case LINUX_REBOOT_CMD_POWER_OFF: | |
342 | kernel_power_off(); | |
343 | do_exit(0); | |
344 | break; | |
345 | ||
346 | case LINUX_REBOOT_CMD_RESTART2: | |
972ee83d RH |
347 | ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1); |
348 | if (ret < 0) { | |
15d94b82 RH |
349 | ret = -EFAULT; |
350 | break; | |
351 | } | |
352 | buffer[sizeof(buffer) - 1] = '\0'; | |
353 | ||
354 | kernel_restart(buffer); | |
355 | break; | |
356 | ||
2965faa5 | 357 | #ifdef CONFIG_KEXEC_CORE |
15d94b82 RH |
358 | case LINUX_REBOOT_CMD_KEXEC: |
359 | ret = kernel_kexec(); | |
360 | break; | |
361 | #endif | |
362 | ||
363 | #ifdef CONFIG_HIBERNATION | |
364 | case LINUX_REBOOT_CMD_SW_SUSPEND: | |
365 | ret = hibernate(); | |
366 | break; | |
367 | #endif | |
368 | ||
369 | default: | |
370 | ret = -EINVAL; | |
371 | break; | |
372 | } | |
373 | mutex_unlock(&reboot_mutex); | |
374 | return ret; | |
375 | } | |
376 | ||
377 | static void deferred_cad(struct work_struct *dummy) | |
378 | { | |
379 | kernel_restart(NULL); | |
380 | } | |
381 | ||
382 | /* | |
383 | * This function gets called by ctrl-alt-del - ie the keyboard interrupt. | |
384 | * As it's called within an interrupt, it may NOT sync: the only choice | |
385 | * is whether to reboot at once, or just ignore the ctrl-alt-del. | |
386 | */ | |
387 | void ctrl_alt_del(void) | |
388 | { | |
389 | static DECLARE_WORK(cad_work, deferred_cad); | |
390 | ||
391 | if (C_A_D) | |
392 | schedule_work(&cad_work); | |
393 | else | |
394 | kill_cad_pid(SIGINT, 1); | |
395 | } | |
396 | ||
397 | char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff"; | |
7a54f46b | 398 | static const char reboot_cmd[] = "/sbin/reboot"; |
15d94b82 | 399 | |
7a54f46b | 400 | static int run_cmd(const char *cmd) |
15d94b82 RH |
401 | { |
402 | char **argv; | |
403 | static char *envp[] = { | |
404 | "HOME=/", | |
405 | "PATH=/sbin:/bin:/usr/sbin:/usr/bin", | |
406 | NULL | |
407 | }; | |
408 | int ret; | |
7a54f46b | 409 | argv = argv_split(GFP_KERNEL, cmd, NULL); |
15d94b82 RH |
410 | if (argv) { |
411 | ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
412 | argv_free(argv); | |
413 | } else { | |
15d94b82 RH |
414 | ret = -ENOMEM; |
415 | } | |
416 | ||
7a54f46b JS |
417 | return ret; |
418 | } | |
419 | ||
420 | static int __orderly_reboot(void) | |
421 | { | |
422 | int ret; | |
423 | ||
424 | ret = run_cmd(reboot_cmd); | |
425 | ||
426 | if (ret) { | |
427 | pr_warn("Failed to start orderly reboot: forcing the issue\n"); | |
428 | emergency_sync(); | |
429 | kernel_restart(NULL); | |
430 | } | |
431 | ||
432 | return ret; | |
433 | } | |
434 | ||
435 | static int __orderly_poweroff(bool force) | |
436 | { | |
437 | int ret; | |
438 | ||
439 | ret = run_cmd(poweroff_cmd); | |
440 | ||
15d94b82 | 441 | if (ret && force) { |
972ee83d | 442 | pr_warn("Failed to start orderly shutdown: forcing the issue\n"); |
7a54f46b | 443 | |
15d94b82 RH |
444 | /* |
445 | * I guess this should try to kick off some daemon to sync and | |
446 | * poweroff asap. Or not even bother syncing if we're doing an | |
447 | * emergency shutdown? | |
448 | */ | |
449 | emergency_sync(); | |
450 | kernel_power_off(); | |
451 | } | |
452 | ||
453 | return ret; | |
454 | } | |
455 | ||
456 | static bool poweroff_force; | |
457 | ||
458 | static void poweroff_work_func(struct work_struct *work) | |
459 | { | |
460 | __orderly_poweroff(poweroff_force); | |
461 | } | |
462 | ||
463 | static DECLARE_WORK(poweroff_work, poweroff_work_func); | |
464 | ||
465 | /** | |
466 | * orderly_poweroff - Trigger an orderly system poweroff | |
467 | * @force: force poweroff if command execution fails | |
468 | * | |
469 | * This may be called from any context to trigger a system shutdown. | |
470 | * If the orderly shutdown fails, it will force an immediate shutdown. | |
471 | */ | |
7a54f46b | 472 | void orderly_poweroff(bool force) |
15d94b82 RH |
473 | { |
474 | if (force) /* do not override the pending "true" */ | |
475 | poweroff_force = true; | |
476 | schedule_work(&poweroff_work); | |
15d94b82 RH |
477 | } |
478 | EXPORT_SYMBOL_GPL(orderly_poweroff); | |
1b3a5d02 | 479 | |
7a54f46b JS |
480 | static void reboot_work_func(struct work_struct *work) |
481 | { | |
482 | __orderly_reboot(); | |
483 | } | |
484 | ||
485 | static DECLARE_WORK(reboot_work, reboot_work_func); | |
486 | ||
487 | /** | |
488 | * orderly_reboot - Trigger an orderly system reboot | |
489 | * | |
490 | * This may be called from any context to trigger a system reboot. | |
491 | * If the orderly reboot fails, it will force an immediate reboot. | |
492 | */ | |
493 | void orderly_reboot(void) | |
494 | { | |
495 | schedule_work(&reboot_work); | |
496 | } | |
497 | EXPORT_SYMBOL_GPL(orderly_reboot); | |
498 | ||
1b3a5d02 RH |
499 | static int __init reboot_setup(char *str) |
500 | { | |
501 | for (;;) { | |
502 | /* | |
503 | * Having anything passed on the command line via | |
504 | * reboot= will cause us to disable DMI checking | |
505 | * below. | |
506 | */ | |
507 | reboot_default = 0; | |
508 | ||
509 | switch (*str) { | |
510 | case 'w': | |
511 | reboot_mode = REBOOT_WARM; | |
512 | break; | |
513 | ||
514 | case 'c': | |
515 | reboot_mode = REBOOT_COLD; | |
516 | break; | |
517 | ||
518 | case 'h': | |
519 | reboot_mode = REBOOT_HARD; | |
520 | break; | |
521 | ||
522 | case 's': | |
616feab7 FF |
523 | { |
524 | int rc; | |
525 | ||
526 | if (isdigit(*(str+1))) { | |
527 | rc = kstrtoint(str+1, 0, &reboot_cpu); | |
528 | if (rc) | |
529 | return rc; | |
530 | } else if (str[1] == 'm' && str[2] == 'p' && | |
531 | isdigit(*(str+3))) { | |
532 | rc = kstrtoint(str+3, 0, &reboot_cpu); | |
533 | if (rc) | |
534 | return rc; | |
535 | } else | |
1b3a5d02 RH |
536 | reboot_mode = REBOOT_SOFT; |
537 | break; | |
616feab7 | 538 | } |
1b3a5d02 RH |
539 | case 'g': |
540 | reboot_mode = REBOOT_GPIO; | |
541 | break; | |
542 | ||
543 | case 'b': | |
544 | case 'a': | |
545 | case 'k': | |
546 | case 't': | |
547 | case 'e': | |
548 | case 'p': | |
549 | reboot_type = *str; | |
550 | break; | |
551 | ||
552 | case 'f': | |
553 | reboot_force = 1; | |
554 | break; | |
555 | } | |
556 | ||
557 | str = strchr(str, ','); | |
558 | if (str) | |
559 | str++; | |
560 | else | |
561 | break; | |
562 | } | |
563 | return 1; | |
564 | } | |
565 | __setup("reboot=", reboot_setup); |