Line data Source code
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 :
24 : int C_A_D = 1;
25 : struct pid *cad_pid;
26 : EXPORT_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
33 : enum 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 : */
42 : int reboot_default = 1;
43 : int reboot_cpu;
44 : enum reboot_type reboot_type = BOOT_ACPI;
45 : int reboot_force;
46 :
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 0 : void emergency_restart(void)
62 : {
63 0 : kmsg_dump(KMSG_DUMP_EMERG);
64 : machine_emergency_restart();
65 0 : }
66 : EXPORT_SYMBOL_GPL(emergency_restart);
67 :
68 0 : void kernel_restart_prepare(char *cmd)
69 : {
70 0 : blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
71 0 : system_state = SYSTEM_RESTART;
72 : usermodehelper_disable();
73 0 : device_shutdown();
74 0 : }
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 2 : int register_reboot_notifier(struct notifier_block *nb)
87 : {
88 2 : 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 0 : int unregister_reboot_notifier(struct notifier_block *nb)
102 : {
103 0 : return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
104 : }
105 : EXPORT_SYMBOL(unregister_reboot_notifier);
106 :
107 : /*
108 : * Notifier list for kernel code which wants to be called
109 : * to restart the system.
110 : */
111 : static 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 : */
151 0 : int register_restart_handler(struct notifier_block *nb)
152 : {
153 0 : 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 0 : int unregister_restart_handler(struct notifier_block *nb)
167 : {
168 0 : 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 0 : void do_kernel_restart(char *cmd)
184 : {
185 0 : atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
186 0 : }
187 :
188 0 : void migrate_to_reboot_cpu(void)
189 : {
190 : /* The boot cpu is always logical cpu 0 */
191 0 : int cpu = reboot_cpu;
192 :
193 : cpu_hotplug_disable();
194 :
195 : /* Make certain the cpu I'm about to reboot on is online */
196 0 : if (!cpu_online(cpu))
197 : cpu = cpumask_first(cpu_online_mask);
198 :
199 : /* Prevent races with other tasks migrating this task */
200 0 : current->flags |= PF_NO_SETAFFINITY;
201 :
202 : /* Make certain I only run on the appropriate processor */
203 0 : set_cpus_allowed_ptr(current, cpumask_of(cpu));
204 0 : }
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 0 : void kernel_restart(char *cmd)
215 : {
216 0 : kernel_restart_prepare(cmd);
217 0 : migrate_to_reboot_cpu();
218 0 : syscore_shutdown();
219 0 : if (!cmd)
220 0 : pr_emerg("Restarting system\n");
221 : else
222 0 : pr_emerg("Restarting system with command '%s'\n", cmd);
223 0 : kmsg_dump(KMSG_DUMP_RESTART);
224 0 : machine_restart(cmd);
225 0 : }
226 : EXPORT_SYMBOL_GPL(kernel_restart);
227 :
228 0 : static void kernel_shutdown_prepare(enum system_states state)
229 : {
230 0 : blocking_notifier_call_chain(&reboot_notifier_list,
231 : (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
232 0 : system_state = state;
233 : usermodehelper_disable();
234 0 : device_shutdown();
235 0 : }
236 : /**
237 : * kernel_halt - halt the system
238 : *
239 : * Shutdown everything and perform a clean system halt.
240 : */
241 0 : void kernel_halt(void)
242 : {
243 0 : kernel_shutdown_prepare(SYSTEM_HALT);
244 0 : migrate_to_reboot_cpu();
245 0 : syscore_shutdown();
246 0 : pr_emerg("System halted\n");
247 0 : kmsg_dump(KMSG_DUMP_HALT);
248 0 : machine_halt();
249 0 : }
250 : EXPORT_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 : */
257 0 : void kernel_power_off(void)
258 : {
259 0 : kernel_shutdown_prepare(SYSTEM_POWER_OFF);
260 0 : if (pm_power_off_prepare)
261 0 : pm_power_off_prepare();
262 0 : migrate_to_reboot_cpu();
263 0 : syscore_shutdown();
264 0 : pr_emerg("Power down\n");
265 0 : kmsg_dump(KMSG_DUMP_POWEROFF);
266 0 : machine_power_off();
267 0 : }
268 : EXPORT_SYMBOL_GPL(kernel_power_off);
269 :
270 : static 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 : */
280 2 : SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
281 : void __user *, arg)
282 : {
283 1 : 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 1 : if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
289 : return -EPERM;
290 :
291 : /* For safety, we require "magic" arguments. */
292 2 : if (magic1 != LINUX_REBOOT_MAGIC1 ||
293 2 : (magic2 != LINUX_REBOOT_MAGIC2 &&
294 1 : magic2 != LINUX_REBOOT_MAGIC2A &&
295 0 : magic2 != LINUX_REBOOT_MAGIC2B &&
296 0 : 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 1 : ret = reboot_pid_ns(pid_ns, cmd);
305 1 : 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 1 : if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
312 : cmd = LINUX_REBOOT_CMD_HALT;
313 :
314 1 : mutex_lock(&reboot_mutex);
315 1 : switch (cmd) {
316 : case LINUX_REBOOT_CMD_RESTART:
317 0 : kernel_restart(NULL);
318 : break;
319 :
320 : case LINUX_REBOOT_CMD_CAD_ON:
321 0 : C_A_D = 1;
322 : break;
323 :
324 : case LINUX_REBOOT_CMD_CAD_OFF:
325 1 : C_A_D = 0;
326 : break;
327 :
328 : case LINUX_REBOOT_CMD_HALT:
329 0 : kernel_halt();
330 0 : do_exit(0);
331 : panic("cannot halt");
332 :
333 : case LINUX_REBOOT_CMD_POWER_OFF:
334 0 : kernel_power_off();
335 0 : do_exit(0);
336 : break;
337 :
338 : case LINUX_REBOOT_CMD_RESTART2:
339 0 : ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
340 0 : if (ret < 0) {
341 : ret = -EFAULT;
342 : break;
343 : }
344 0 : buffer[sizeof(buffer) - 1] = '\0';
345 :
346 0 : kernel_restart(buffer);
347 : break;
348 :
349 : #ifdef CONFIG_KEXEC
350 : case LINUX_REBOOT_CMD_KEXEC:
351 0 : 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 1 : mutex_unlock(&reboot_mutex);
366 : return ret;
367 : }
368 :
369 0 : static void deferred_cad(struct work_struct *dummy)
370 : {
371 0 : kernel_restart(NULL);
372 0 : }
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 : */
379 0 : void ctrl_alt_del(void)
380 : {
381 : static DECLARE_WORK(cad_work, deferred_cad);
382 :
383 0 : if (C_A_D)
384 : schedule_work(&cad_work);
385 : else
386 : kill_cad_pid(SIGINT, 1);
387 0 : }
388 :
389 : char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
390 :
391 0 : static int __orderly_poweroff(bool force)
392 : {
393 : char **argv;
394 : static char *envp[] = {
395 : "HOME=/",
396 : "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
397 : NULL
398 : };
399 : int ret;
400 :
401 0 : argv = argv_split(GFP_KERNEL, poweroff_cmd, NULL);
402 0 : if (argv) {
403 0 : ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
404 0 : argv_free(argv);
405 : } else {
406 : ret = -ENOMEM;
407 : }
408 :
409 0 : if (ret && force) {
410 0 : pr_warn("Failed to start orderly shutdown: forcing the issue\n");
411 : /*
412 : * I guess this should try to kick off some daemon to sync and
413 : * poweroff asap. Or not even bother syncing if we're doing an
414 : * emergency shutdown?
415 : */
416 0 : emergency_sync();
417 0 : kernel_power_off();
418 : }
419 :
420 0 : return ret;
421 : }
422 :
423 : static bool poweroff_force;
424 :
425 0 : static void poweroff_work_func(struct work_struct *work)
426 : {
427 0 : __orderly_poweroff(poweroff_force);
428 0 : }
429 :
430 : static DECLARE_WORK(poweroff_work, poweroff_work_func);
431 :
432 : /**
433 : * orderly_poweroff - Trigger an orderly system poweroff
434 : * @force: force poweroff if command execution fails
435 : *
436 : * This may be called from any context to trigger a system shutdown.
437 : * If the orderly shutdown fails, it will force an immediate shutdown.
438 : */
439 0 : int orderly_poweroff(bool force)
440 : {
441 0 : if (force) /* do not override the pending "true" */
442 0 : poweroff_force = true;
443 : schedule_work(&poweroff_work);
444 0 : return 0;
445 : }
446 : EXPORT_SYMBOL_GPL(orderly_poweroff);
447 :
448 0 : static int __init reboot_setup(char *str)
449 : {
450 : for (;;) {
451 : /*
452 : * Having anything passed on the command line via
453 : * reboot= will cause us to disable DMI checking
454 : * below.
455 : */
456 0 : reboot_default = 0;
457 :
458 0 : switch (*str) {
459 : case 'w':
460 0 : reboot_mode = REBOOT_WARM;
461 0 : break;
462 :
463 : case 'c':
464 0 : reboot_mode = REBOOT_COLD;
465 0 : break;
466 :
467 : case 'h':
468 0 : reboot_mode = REBOOT_HARD;
469 0 : break;
470 :
471 : case 's':
472 : {
473 : int rc;
474 :
475 0 : if (isdigit(*(str+1))) {
476 0 : rc = kstrtoint(str+1, 0, &reboot_cpu);
477 0 : if (rc)
478 : return rc;
479 0 : } else if (str[1] == 'm' && str[2] == 'p' &&
480 0 : isdigit(*(str+3))) {
481 0 : rc = kstrtoint(str+3, 0, &reboot_cpu);
482 0 : if (rc)
483 : return rc;
484 : } else
485 0 : reboot_mode = REBOOT_SOFT;
486 : break;
487 : }
488 : case 'g':
489 0 : reboot_mode = REBOOT_GPIO;
490 0 : break;
491 :
492 : case 'b':
493 : case 'a':
494 : case 'k':
495 : case 't':
496 : case 'e':
497 : case 'p':
498 0 : reboot_type = *str;
499 0 : break;
500 :
501 : case 'f':
502 0 : reboot_force = 1;
503 0 : break;
504 : }
505 :
506 0 : str = strchr(str, ',');
507 0 : if (str)
508 0 : str++;
509 : else
510 : break;
511 0 : }
512 : return 1;
513 : }
514 : __setup("reboot=", reboot_setup);
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