projects/linux·blob v3.11 · refs

419 lines · 9.2 KiB

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
35int reboot_default;
36int reboot_cpu;
37enum reboot_type reboot_type = BOOT_ACPI;
38int reboot_force;
39
40/*
41 * If set, this is used for preparing the system to power off.
42 */
43
44void (*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 */
54void emergency_restart(void)
55{
56 kmsg_dump(KMSG_DUMP_EMERG);
57 machine_emergency_restart();
58}
59EXPORT_SYMBOL_GPL(emergency_restart);
60
61void 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 */
79int register_reboot_notifier(struct notifier_block *nb)
80{
81 return blocking_notifier_chain_register(&reboot_notifier_list, nb);
82}
83EXPORT_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 */
94int unregister_reboot_notifier(struct notifier_block *nb)
95{
96 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
97}
98EXPORT_SYMBOL(unregister_reboot_notifier);
99
100static void migrate_to_reboot_cpu(void)
101{
102 /* The boot cpu is always logical cpu 0 */
103 int cpu = reboot_cpu;
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 */
126void kernel_restart(char *cmd)
127{
128 kernel_restart_prepare(cmd);
129 migrate_to_reboot_cpu();
130 syscore_shutdown();
131 if (!cmd)
132 pr_emerg("Restarting system\n");
133 else
134 pr_emerg("Restarting system with command '%s'\n", cmd);
135 kmsg_dump(KMSG_DUMP_RESTART);
136 machine_restart(cmd);
137}
138EXPORT_SYMBOL_GPL(kernel_restart);
139
140static void kernel_shutdown_prepare(enum system_states state)
141{
142 blocking_notifier_call_chain(&reboot_notifier_list,
143 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
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 */
153void kernel_halt(void)
154{
155 kernel_shutdown_prepare(SYSTEM_HALT);
156 migrate_to_reboot_cpu();
157 syscore_shutdown();
158 pr_emerg("System halted\n");
159 kmsg_dump(KMSG_DUMP_HALT);
160 machine_halt();
161}
162EXPORT_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 */
169void 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();
176 pr_emerg("Power down\n");
177 kmsg_dump(KMSG_DUMP_POWEROFF);
178 machine_power_off();
179}
180EXPORT_SYMBOL_GPL(kernel_power_off);
181
182static 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 */
192SYSCALL_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 ||
205 (magic2 != LINUX_REBOOT_MAGIC2 &&
206 magic2 != LINUX_REBOOT_MAGIC2A &&
207 magic2 != LINUX_REBOOT_MAGIC2B &&
208 magic2 != LINUX_REBOOT_MAGIC2C))
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:
251 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
252 if (ret < 0) {
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
281static 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 */
291void 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
301char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
302
303static 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 {
318 ret = -ENOMEM;
319 }
320
321 if (ret && force) {
322 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
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
335static bool poweroff_force;
336
337static void poweroff_work_func(struct work_struct *work)
338{
339 __orderly_poweroff(poweroff_force);
340}
341
342static 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 */
351int 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}
358EXPORT_SYMBOL_GPL(orderly_poweroff);
359
360static 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);