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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 | ||
35 | int reboot_default; | |
36 | int reboot_cpu; | |
37 | enum reboot_type reboot_type = BOOT_ACPI; | |
38 | int reboot_force; | |
39 | ||
15d94b82 RH |
40 | /* |
41 | * If set, this is used for preparing the system to power off. | |
42 | */ | |
43 | ||
44 | void (*pm_power_off_prepare)(void); | |
45 | ||
46 | /** | |
47 | * emergency_restart - reboot the system | |
48 | * | |
49 | * Without shutting down any hardware or taking any locks | |
50 | * reboot the system. This is called when we know we are in | |
51 | * trouble so this is our best effort to reboot. This is | |
52 | * safe to call in interrupt context. | |
53 | */ | |
54 | void emergency_restart(void) | |
55 | { | |
56 | kmsg_dump(KMSG_DUMP_EMERG); | |
57 | machine_emergency_restart(); | |
58 | } | |
59 | EXPORT_SYMBOL_GPL(emergency_restart); | |
60 | ||
61 | void kernel_restart_prepare(char *cmd) | |
62 | { | |
63 | blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); | |
64 | system_state = SYSTEM_RESTART; | |
65 | usermodehelper_disable(); | |
66 | device_shutdown(); | |
67 | } | |
68 | ||
69 | /** | |
70 | * register_reboot_notifier - Register function to be called at reboot time | |
71 | * @nb: Info about notifier function to be called | |
72 | * | |
73 | * Registers a function with the list of functions | |
74 | * to be called at reboot time. | |
75 | * | |
76 | * Currently always returns zero, as blocking_notifier_chain_register() | |
77 | * always returns zero. | |
78 | */ | |
79 | int register_reboot_notifier(struct notifier_block *nb) | |
80 | { | |
81 | return blocking_notifier_chain_register(&reboot_notifier_list, nb); | |
82 | } | |
83 | EXPORT_SYMBOL(register_reboot_notifier); | |
84 | ||
85 | /** | |
86 | * unregister_reboot_notifier - Unregister previously registered reboot notifier | |
87 | * @nb: Hook to be unregistered | |
88 | * | |
89 | * Unregisters a previously registered reboot | |
90 | * notifier function. | |
91 | * | |
92 | * Returns zero on success, or %-ENOENT on failure. | |
93 | */ | |
94 | int unregister_reboot_notifier(struct notifier_block *nb) | |
95 | { | |
96 | return blocking_notifier_chain_unregister(&reboot_notifier_list, nb); | |
97 | } | |
98 | EXPORT_SYMBOL(unregister_reboot_notifier); | |
99 | ||
100 | static void migrate_to_reboot_cpu(void) | |
101 | { | |
102 | /* The boot cpu is always logical cpu 0 */ | |
1b3a5d02 | 103 | int cpu = reboot_cpu; |
15d94b82 RH |
104 | |
105 | cpu_hotplug_disable(); | |
106 | ||
107 | /* Make certain the cpu I'm about to reboot on is online */ | |
108 | if (!cpu_online(cpu)) | |
109 | cpu = cpumask_first(cpu_online_mask); | |
110 | ||
111 | /* Prevent races with other tasks migrating this task */ | |
112 | current->flags |= PF_NO_SETAFFINITY; | |
113 | ||
114 | /* Make certain I only run on the appropriate processor */ | |
115 | set_cpus_allowed_ptr(current, cpumask_of(cpu)); | |
116 | } | |
117 | ||
118 | /** | |
119 | * kernel_restart - reboot the system | |
120 | * @cmd: pointer to buffer containing command to execute for restart | |
121 | * or %NULL | |
122 | * | |
123 | * Shutdown everything and perform a clean reboot. | |
124 | * This is not safe to call in interrupt context. | |
125 | */ | |
126 | void kernel_restart(char *cmd) | |
127 | { | |
128 | kernel_restart_prepare(cmd); | |
129 | migrate_to_reboot_cpu(); | |
130 | syscore_shutdown(); | |
131 | if (!cmd) | |
972ee83d | 132 | pr_emerg("Restarting system\n"); |
15d94b82 | 133 | else |
972ee83d | 134 | pr_emerg("Restarting system with command '%s'\n", cmd); |
15d94b82 RH |
135 | kmsg_dump(KMSG_DUMP_RESTART); |
136 | machine_restart(cmd); | |
137 | } | |
138 | EXPORT_SYMBOL_GPL(kernel_restart); | |
139 | ||
140 | static void kernel_shutdown_prepare(enum system_states state) | |
141 | { | |
142 | blocking_notifier_call_chain(&reboot_notifier_list, | |
972ee83d | 143 | (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL); |
15d94b82 RH |
144 | system_state = state; |
145 | usermodehelper_disable(); | |
146 | device_shutdown(); | |
147 | } | |
148 | /** | |
149 | * kernel_halt - halt the system | |
150 | * | |
151 | * Shutdown everything and perform a clean system halt. | |
152 | */ | |
153 | void kernel_halt(void) | |
154 | { | |
155 | kernel_shutdown_prepare(SYSTEM_HALT); | |
156 | migrate_to_reboot_cpu(); | |
157 | syscore_shutdown(); | |
972ee83d | 158 | pr_emerg("System halted\n"); |
15d94b82 RH |
159 | kmsg_dump(KMSG_DUMP_HALT); |
160 | machine_halt(); | |
161 | } | |
15d94b82 RH |
162 | EXPORT_SYMBOL_GPL(kernel_halt); |
163 | ||
164 | /** | |
165 | * kernel_power_off - power_off the system | |
166 | * | |
167 | * Shutdown everything and perform a clean system power_off. | |
168 | */ | |
169 | void kernel_power_off(void) | |
170 | { | |
171 | kernel_shutdown_prepare(SYSTEM_POWER_OFF); | |
172 | if (pm_power_off_prepare) | |
173 | pm_power_off_prepare(); | |
174 | migrate_to_reboot_cpu(); | |
175 | syscore_shutdown(); | |
972ee83d | 176 | pr_emerg("Power down\n"); |
15d94b82 RH |
177 | kmsg_dump(KMSG_DUMP_POWEROFF); |
178 | machine_power_off(); | |
179 | } | |
180 | EXPORT_SYMBOL_GPL(kernel_power_off); | |
181 | ||
182 | static DEFINE_MUTEX(reboot_mutex); | |
183 | ||
184 | /* | |
185 | * Reboot system call: for obvious reasons only root may call it, | |
186 | * and even root needs to set up some magic numbers in the registers | |
187 | * so that some mistake won't make this reboot the whole machine. | |
188 | * You can also set the meaning of the ctrl-alt-del-key here. | |
189 | * | |
190 | * reboot doesn't sync: do that yourself before calling this. | |
191 | */ | |
192 | SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, | |
193 | void __user *, arg) | |
194 | { | |
195 | struct pid_namespace *pid_ns = task_active_pid_ns(current); | |
196 | char buffer[256]; | |
197 | int ret = 0; | |
198 | ||
199 | /* We only trust the superuser with rebooting the system. */ | |
200 | if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT)) | |
201 | return -EPERM; | |
202 | ||
203 | /* For safety, we require "magic" arguments. */ | |
204 | if (magic1 != LINUX_REBOOT_MAGIC1 || | |
972ee83d RH |
205 | (magic2 != LINUX_REBOOT_MAGIC2 && |
206 | magic2 != LINUX_REBOOT_MAGIC2A && | |
15d94b82 | 207 | magic2 != LINUX_REBOOT_MAGIC2B && |
972ee83d | 208 | magic2 != LINUX_REBOOT_MAGIC2C)) |
15d94b82 RH |
209 | return -EINVAL; |
210 | ||
211 | /* | |
212 | * If pid namespaces are enabled and the current task is in a child | |
213 | * pid_namespace, the command is handled by reboot_pid_ns() which will | |
214 | * call do_exit(). | |
215 | */ | |
216 | ret = reboot_pid_ns(pid_ns, cmd); | |
217 | if (ret) | |
218 | return ret; | |
219 | ||
220 | /* Instead of trying to make the power_off code look like | |
221 | * halt when pm_power_off is not set do it the easy way. | |
222 | */ | |
223 | if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off) | |
224 | cmd = LINUX_REBOOT_CMD_HALT; | |
225 | ||
226 | mutex_lock(&reboot_mutex); | |
227 | switch (cmd) { | |
228 | case LINUX_REBOOT_CMD_RESTART: | |
229 | kernel_restart(NULL); | |
230 | break; | |
231 | ||
232 | case LINUX_REBOOT_CMD_CAD_ON: | |
233 | C_A_D = 1; | |
234 | break; | |
235 | ||
236 | case LINUX_REBOOT_CMD_CAD_OFF: | |
237 | C_A_D = 0; | |
238 | break; | |
239 | ||
240 | case LINUX_REBOOT_CMD_HALT: | |
241 | kernel_halt(); | |
242 | do_exit(0); | |
243 | panic("cannot halt"); | |
244 | ||
245 | case LINUX_REBOOT_CMD_POWER_OFF: | |
246 | kernel_power_off(); | |
247 | do_exit(0); | |
248 | break; | |
249 | ||
250 | case LINUX_REBOOT_CMD_RESTART2: | |
972ee83d RH |
251 | ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1); |
252 | if (ret < 0) { | |
15d94b82 RH |
253 | ret = -EFAULT; |
254 | break; | |
255 | } | |
256 | buffer[sizeof(buffer) - 1] = '\0'; | |
257 | ||
258 | kernel_restart(buffer); | |
259 | break; | |
260 | ||
261 | #ifdef CONFIG_KEXEC | |
262 | case LINUX_REBOOT_CMD_KEXEC: | |
263 | ret = kernel_kexec(); | |
264 | break; | |
265 | #endif | |
266 | ||
267 | #ifdef CONFIG_HIBERNATION | |
268 | case LINUX_REBOOT_CMD_SW_SUSPEND: | |
269 | ret = hibernate(); | |
270 | break; | |
271 | #endif | |
272 | ||
273 | default: | |
274 | ret = -EINVAL; | |
275 | break; | |
276 | } | |
277 | mutex_unlock(&reboot_mutex); | |
278 | return ret; | |
279 | } | |
280 | ||
281 | static void deferred_cad(struct work_struct *dummy) | |
282 | { | |
283 | kernel_restart(NULL); | |
284 | } | |
285 | ||
286 | /* | |
287 | * This function gets called by ctrl-alt-del - ie the keyboard interrupt. | |
288 | * As it's called within an interrupt, it may NOT sync: the only choice | |
289 | * is whether to reboot at once, or just ignore the ctrl-alt-del. | |
290 | */ | |
291 | void ctrl_alt_del(void) | |
292 | { | |
293 | static DECLARE_WORK(cad_work, deferred_cad); | |
294 | ||
295 | if (C_A_D) | |
296 | schedule_work(&cad_work); | |
297 | else | |
298 | kill_cad_pid(SIGINT, 1); | |
299 | } | |
300 | ||
301 | char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff"; | |
302 | ||
303 | static int __orderly_poweroff(bool force) | |
304 | { | |
305 | char **argv; | |
306 | static char *envp[] = { | |
307 | "HOME=/", | |
308 | "PATH=/sbin:/bin:/usr/sbin:/usr/bin", | |
309 | NULL | |
310 | }; | |
311 | int ret; | |
312 | ||
313 | argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL); | |
314 | if (argv) { | |
315 | ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); | |
316 | argv_free(argv); | |
317 | } else { | |
15d94b82 RH |
318 | ret = -ENOMEM; |
319 | } | |
320 | ||
321 | if (ret && force) { | |
972ee83d | 322 | pr_warn("Failed to start orderly shutdown: forcing the issue\n"); |
15d94b82 RH |
323 | /* |
324 | * I guess this should try to kick off some daemon to sync and | |
325 | * poweroff asap. Or not even bother syncing if we're doing an | |
326 | * emergency shutdown? | |
327 | */ | |
328 | emergency_sync(); | |
329 | kernel_power_off(); | |
330 | } | |
331 | ||
332 | return ret; | |
333 | } | |
334 | ||
335 | static bool poweroff_force; | |
336 | ||
337 | static void poweroff_work_func(struct work_struct *work) | |
338 | { | |
339 | __orderly_poweroff(poweroff_force); | |
340 | } | |
341 | ||
342 | static DECLARE_WORK(poweroff_work, poweroff_work_func); | |
343 | ||
344 | /** | |
345 | * orderly_poweroff - Trigger an orderly system poweroff | |
346 | * @force: force poweroff if command execution fails | |
347 | * | |
348 | * This may be called from any context to trigger a system shutdown. | |
349 | * If the orderly shutdown fails, it will force an immediate shutdown. | |
350 | */ | |
351 | int orderly_poweroff(bool force) | |
352 | { | |
353 | if (force) /* do not override the pending "true" */ | |
354 | poweroff_force = true; | |
355 | schedule_work(&poweroff_work); | |
356 | return 0; | |
357 | } | |
358 | EXPORT_SYMBOL_GPL(orderly_poweroff); | |
1b3a5d02 RH |
359 | |
360 | static int __init reboot_setup(char *str) | |
361 | { | |
362 | for (;;) { | |
363 | /* | |
364 | * Having anything passed on the command line via | |
365 | * reboot= will cause us to disable DMI checking | |
366 | * below. | |
367 | */ | |
368 | reboot_default = 0; | |
369 | ||
370 | switch (*str) { | |
371 | case 'w': | |
372 | reboot_mode = REBOOT_WARM; | |
373 | break; | |
374 | ||
375 | case 'c': | |
376 | reboot_mode = REBOOT_COLD; | |
377 | break; | |
378 | ||
379 | case 'h': | |
380 | reboot_mode = REBOOT_HARD; | |
381 | break; | |
382 | ||
383 | case 's': | |
384 | if (isdigit(*(str+1))) | |
385 | reboot_cpu = simple_strtoul(str+1, NULL, 0); | |
386 | else if (str[1] == 'm' && str[2] == 'p' && | |
387 | isdigit(*(str+3))) | |
388 | reboot_cpu = simple_strtoul(str+3, NULL, 0); | |
389 | else | |
390 | reboot_mode = REBOOT_SOFT; | |
391 | break; | |
392 | ||
393 | case 'g': | |
394 | reboot_mode = REBOOT_GPIO; | |
395 | break; | |
396 | ||
397 | case 'b': | |
398 | case 'a': | |
399 | case 'k': | |
400 | case 't': | |
401 | case 'e': | |
402 | case 'p': | |
403 | reboot_type = *str; | |
404 | break; | |
405 | ||
406 | case 'f': | |
407 | reboot_force = 1; | |
408 | break; | |
409 | } | |
410 | ||
411 | str = strchr(str, ','); | |
412 | if (str) | |
413 | str++; | |
414 | else | |
415 | break; | |
416 | } | |
417 | return 1; | |
418 | } | |
419 | __setup("reboot=", reboot_setup); |