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 26 static int C_A_D = 1; 27 struct pid *cad_pid; 28 EXPORT_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 35 enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE; 36 EXPORT_SYMBOL_GPL(reboot_mode); 37 enum reboot_mode panic_reboot_mode = REBOOT_UNDEFINED; 38 39 /* 40 * This variable is used privately to keep track of whether or not 41 * reboot_type is still set to its default value (i.e., reboot= hasn't 42 * been set on the command line). This is needed so that we can 43 * suppress DMI scanning for reboot quirks. Without it, it's 44 * impossible to override a faulty reboot quirk without recompiling. 45 */ 46 int reboot_default = 1; 47 int reboot_cpu; 48 enum reboot_type reboot_type = BOOT_ACPI; 49 int reboot_force; 50 51 struct sys_off_handler { 52 struct notifier_block nb; 53 int (*sys_off_cb)(struct sys_off_data *data); 54 void *cb_data; 55 enum sys_off_mode mode; 56 bool blocking; 57 void *list; 58 }; 59 60 /* 61 * Temporary stub that prevents linkage failure while we're in process 62 * of removing all uses of legacy pm_power_off() around the kernel. 63 */ 64 void __weak (*pm_power_off)(void); 65 66 /** 67 * emergency_restart - reboot the system 68 * 69 * Without shutting down any hardware or taking any locks 70 * reboot the system. This is called when we know we are in 71 * trouble so this is our best effort to reboot. This is 72 * safe to call in interrupt context. 73 */ 74 void emergency_restart(void) 75 { 76 kmsg_dump(KMSG_DUMP_EMERG); 77 machine_emergency_restart(); 78 } 79 EXPORT_SYMBOL_GPL(emergency_restart); 80 81 void kernel_restart_prepare(char *cmd) 82 { 83 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); 84 system_state = SYSTEM_RESTART; 85 usermodehelper_disable(); 86 device_shutdown(); 87 } 88 89 /** 90 * register_reboot_notifier - Register function to be called at reboot time 91 * @nb: Info about notifier function to be called 92 * 93 * Registers a function with the list of functions 94 * to be called at reboot time. 95 * 96 * Currently always returns zero, as blocking_notifier_chain_register() 97 * always returns zero. 98 */ 99 int register_reboot_notifier(struct notifier_block *nb) 100 { 101 return blocking_notifier_chain_register(&reboot_notifier_list, nb); 102 } 103 EXPORT_SYMBOL(register_reboot_notifier); 104 105 /** 106 * unregister_reboot_notifier - Unregister previously registered reboot notifier 107 * @nb: Hook to be unregistered 108 * 109 * Unregisters a previously registered reboot 110 * notifier function. 111 * 112 * Returns zero on success, or %-ENOENT on failure. 113 */ 114 int unregister_reboot_notifier(struct notifier_block *nb) 115 { 116 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb); 117 } 118 EXPORT_SYMBOL(unregister_reboot_notifier); 119 120 static void devm_unregister_reboot_notifier(struct device *dev, void *res) 121 { 122 WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res)); 123 } 124 125 int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb) 126 { 127 struct notifier_block **rcnb; 128 int ret; 129 130 rcnb = devres_alloc(devm_unregister_reboot_notifier, 131 sizeof(*rcnb), GFP_KERNEL); 132 if (!rcnb) 133 return -ENOMEM; 134 135 ret = register_reboot_notifier(nb); 136 if (!ret) { 137 *rcnb = nb; 138 devres_add(dev, rcnb); 139 } else { 140 devres_free(rcnb); 141 } 142 143 return ret; 144 } 145 EXPORT_SYMBOL(devm_register_reboot_notifier); 146 147 /* 148 * Notifier list for kernel code which wants to be called 149 * to restart the system. 150 */ 151 static ATOMIC_NOTIFIER_HEAD(restart_handler_list); 152 153 /** 154 * register_restart_handler - Register function to be called to reset 155 * the system 156 * @nb: Info about handler function to be called 157 * @nb->priority: Handler priority. Handlers should follow the 158 * following guidelines for setting priorities. 159 * 0: Restart handler of last resort, 160 * with limited restart capabilities 161 * 128: Default restart handler; use if no other 162 * restart handler is expected to be available, 163 * and/or if restart functionality is 164 * sufficient to restart the entire system 165 * 255: Highest priority restart handler, will 166 * preempt all other restart handlers 167 * 168 * Registers a function with code to be called to restart the 169 * system. 170 * 171 * Registered functions will be called from machine_restart as last 172 * step of the restart sequence (if the architecture specific 173 * machine_restart function calls do_kernel_restart - see below 174 * for details). 175 * Registered functions are expected to restart the system immediately. 176 * If more than one function is registered, the restart handler priority 177 * selects which function will be called first. 178 * 179 * Restart handlers are expected to be registered from non-architecture 180 * code, typically from drivers. A typical use case would be a system 181 * where restart functionality is provided through a watchdog. Multiple 182 * restart handlers may exist; for example, one restart handler might 183 * restart the entire system, while another only restarts the CPU. 184 * In such cases, the restart handler which only restarts part of the 185 * hardware is expected to register with low priority to ensure that 186 * it only runs if no other means to restart the system is available. 187 * 188 * Currently always returns zero, as atomic_notifier_chain_register() 189 * always returns zero. 190 */ 191 int register_restart_handler(struct notifier_block *nb) 192 { 193 return atomic_notifier_chain_register(&restart_handler_list, nb); 194 } 195 EXPORT_SYMBOL(register_restart_handler); 196 197 /** 198 * unregister_restart_handler - Unregister previously registered 199 * restart handler 200 * @nb: Hook to be unregistered 201 * 202 * Unregisters a previously registered restart handler function. 203 * 204 * Returns zero on success, or %-ENOENT on failure. 205 */ 206 int unregister_restart_handler(struct notifier_block *nb) 207 { 208 return atomic_notifier_chain_unregister(&restart_handler_list, nb); 209 } 210 EXPORT_SYMBOL(unregister_restart_handler); 211 212 /** 213 * do_kernel_restart - Execute kernel restart handler call chain 214 * 215 * Calls functions registered with register_restart_handler. 216 * 217 * Expected to be called from machine_restart as last step of the restart 218 * sequence. 219 * 220 * Restarts the system immediately if a restart handler function has been 221 * registered. Otherwise does nothing. 222 */ 223 void do_kernel_restart(char *cmd) 224 { 225 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd); 226 } 227 228 void migrate_to_reboot_cpu(void) 229 { 230 /* The boot cpu is always logical cpu 0 */ 231 int cpu = reboot_cpu; 232 233 cpu_hotplug_disable(); 234 235 /* Make certain the cpu I'm about to reboot on is online */ 236 if (!cpu_online(cpu)) 237 cpu = cpumask_first(cpu_online_mask); 238 239 /* Prevent races with other tasks migrating this task */ 240 current->flags |= PF_NO_SETAFFINITY; 241 242 /* Make certain I only run on the appropriate processor */ 243 set_cpus_allowed_ptr(current, cpumask_of(cpu)); 244 } 245 246 /** 247 * kernel_restart - reboot the system 248 * @cmd: pointer to buffer containing command to execute for restart 249 * or %NULL 250 * 251 * Shutdown everything and perform a clean reboot. 252 * This is not safe to call in interrupt context. 253 */ 254 void kernel_restart(char *cmd) 255 { 256 kernel_restart_prepare(cmd); 257 migrate_to_reboot_cpu(); 258 syscore_shutdown(); 259 if (!cmd) 260 pr_emerg("Restarting system\n"); 261 else 262 pr_emerg("Restarting system with command '%s'\n", cmd); 263 kmsg_dump(KMSG_DUMP_SHUTDOWN); 264 machine_restart(cmd); 265 } 266 EXPORT_SYMBOL_GPL(kernel_restart); 267 268 static void kernel_shutdown_prepare(enum system_states state) 269 { 270 blocking_notifier_call_chain(&reboot_notifier_list, 271 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL); 272 system_state = state; 273 usermodehelper_disable(); 274 device_shutdown(); 275 } 276 /** 277 * kernel_halt - halt the system 278 * 279 * Shutdown everything and perform a clean system halt. 280 */ 281 void kernel_halt(void) 282 { 283 kernel_shutdown_prepare(SYSTEM_HALT); 284 migrate_to_reboot_cpu(); 285 syscore_shutdown(); 286 pr_emerg("System halted\n"); 287 kmsg_dump(KMSG_DUMP_SHUTDOWN); 288 machine_halt(); 289 } 290 EXPORT_SYMBOL_GPL(kernel_halt); 291 292 /* 293 * Notifier list for kernel code which wants to be called 294 * to prepare system for power off. 295 */ 296 static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list); 297 298 /* 299 * Notifier list for kernel code which wants to be called 300 * to power off system. 301 */ 302 static ATOMIC_NOTIFIER_HEAD(power_off_handler_list); 303 304 static int sys_off_notify(struct notifier_block *nb, 305 unsigned long mode, void *cmd) 306 { 307 struct sys_off_handler *handler; 308 struct sys_off_data data = {}; 309 310 handler = container_of(nb, struct sys_off_handler, nb); 311 data.cb_data = handler->cb_data; 312 data.mode = mode; 313 data.cmd = cmd; 314 315 return handler->sys_off_cb(&data); 316 } 317 318 static struct sys_off_handler platform_sys_off_handler; 319 320 static struct sys_off_handler *alloc_sys_off_handler(int priority) 321 { 322 struct sys_off_handler *handler; 323 324 /* 325 * Platforms like m68k can't allocate sys_off handler dynamically 326 * at the early boot time because memory allocator isn't available yet. 327 */ 328 if (priority == SYS_OFF_PRIO_PLATFORM) { 329 handler = &platform_sys_off_handler; 330 if (handler->cb_data) 331 return ERR_PTR(-EBUSY); 332 } else { 333 handler = kzalloc(sizeof(*handler), GFP_KERNEL); 334 if (!handler) 335 return ERR_PTR(-ENOMEM); 336 } 337 338 return handler; 339 } 340 341 static void free_sys_off_handler(struct sys_off_handler *handler) 342 { 343 if (handler == &platform_sys_off_handler) 344 memset(handler, 0, sizeof(*handler)); 345 else 346 kfree(handler); 347 } 348 349 /** 350 * register_sys_off_handler - Register sys-off handler 351 * @mode: Sys-off mode 352 * @priority: Handler priority 353 * @callback: Callback function 354 * @cb_data: Callback argument 355 * 356 * Registers system power-off or restart handler that will be invoked 357 * at the step corresponding to the given sys-off mode. Handler's callback 358 * should return NOTIFY_DONE to permit execution of the next handler in 359 * the call chain or NOTIFY_STOP to break the chain (in error case for 360 * example). 361 * 362 * Multiple handlers can be registered at the default priority level. 363 * 364 * Only one handler can be registered at the non-default priority level, 365 * otherwise ERR_PTR(-EBUSY) is returned. 366 * 367 * Returns a new instance of struct sys_off_handler on success, or 368 * an ERR_PTR()-encoded error code otherwise. 369 */ 370 struct sys_off_handler * 371 register_sys_off_handler(enum sys_off_mode mode, 372 int priority, 373 int (*callback)(struct sys_off_data *data), 374 void *cb_data) 375 { 376 struct sys_off_handler *handler; 377 int err; 378 379 handler = alloc_sys_off_handler(priority); 380 if (IS_ERR(handler)) 381 return handler; 382 383 switch (mode) { 384 case SYS_OFF_MODE_POWER_OFF_PREPARE: 385 handler->list = &power_off_prep_handler_list; 386 handler->blocking = true; 387 break; 388 389 case SYS_OFF_MODE_POWER_OFF: 390 handler->list = &power_off_handler_list; 391 break; 392 393 case SYS_OFF_MODE_RESTART: 394 handler->list = &restart_handler_list; 395 break; 396 397 default: 398 free_sys_off_handler(handler); 399 return ERR_PTR(-EINVAL); 400 } 401 402 handler->nb.notifier_call = sys_off_notify; 403 handler->nb.priority = priority; 404 handler->sys_off_cb = callback; 405 handler->cb_data = cb_data; 406 handler->mode = mode; 407 408 if (handler->blocking) { 409 if (priority == SYS_OFF_PRIO_DEFAULT) 410 err = blocking_notifier_chain_register(handler->list, 411 &handler->nb); 412 else 413 err = blocking_notifier_chain_register_unique_prio(handler->list, 414 &handler->nb); 415 } else { 416 if (priority == SYS_OFF_PRIO_DEFAULT) 417 err = atomic_notifier_chain_register(handler->list, 418 &handler->nb); 419 else 420 err = atomic_notifier_chain_register_unique_prio(handler->list, 421 &handler->nb); 422 } 423 424 if (err) { 425 free_sys_off_handler(handler); 426 return ERR_PTR(err); 427 } 428 429 return handler; 430 } 431 EXPORT_SYMBOL_GPL(register_sys_off_handler); 432 433 /** 434 * unregister_sys_off_handler - Unregister sys-off handler 435 * @handler: Sys-off handler 436 * 437 * Unregisters given sys-off handler. 438 */ 439 void unregister_sys_off_handler(struct sys_off_handler *handler) 440 { 441 int err; 442 443 if (!handler) 444 return; 445 446 if (handler->blocking) 447 err = blocking_notifier_chain_unregister(handler->list, 448 &handler->nb); 449 else 450 err = atomic_notifier_chain_unregister(handler->list, 451 &handler->nb); 452 453 /* sanity check, shall never happen */ 454 WARN_ON(err); 455 456 free_sys_off_handler(handler); 457 } 458 EXPORT_SYMBOL_GPL(unregister_sys_off_handler); 459 460 static void devm_unregister_sys_off_handler(void *data) 461 { 462 struct sys_off_handler *handler = data; 463 464 unregister_sys_off_handler(handler); 465 } 466 467 /** 468 * devm_register_sys_off_handler - Register sys-off handler 469 * @dev: Device that registers handler 470 * @mode: Sys-off mode 471 * @priority: Handler priority 472 * @callback: Callback function 473 * @cb_data: Callback argument 474 * 475 * Registers resource-managed sys-off handler. 476 * 477 * Returns zero on success, or error code on failure. 478 */ 479 int devm_register_sys_off_handler(struct device *dev, 480 enum sys_off_mode mode, 481 int priority, 482 int (*callback)(struct sys_off_data *data), 483 void *cb_data) 484 { 485 struct sys_off_handler *handler; 486 487 handler = register_sys_off_handler(mode, priority, callback, cb_data); 488 if (IS_ERR(handler)) 489 return PTR_ERR(handler); 490 491 return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler, 492 handler); 493 } 494 EXPORT_SYMBOL_GPL(devm_register_sys_off_handler); 495 496 /** 497 * devm_register_power_off_handler - Register power-off handler 498 * @dev: Device that registers callback 499 * @callback: Callback function 500 * @cb_data: Callback's argument 501 * 502 * Registers resource-managed sys-off handler with a default priority 503 * and using power-off mode. 504 * 505 * Returns zero on success, or error code on failure. 506 */ 507 int devm_register_power_off_handler(struct device *dev, 508 int (*callback)(struct sys_off_data *data), 509 void *cb_data) 510 { 511 return devm_register_sys_off_handler(dev, 512 SYS_OFF_MODE_POWER_OFF, 513 SYS_OFF_PRIO_DEFAULT, 514 callback, cb_data); 515 } 516 EXPORT_SYMBOL_GPL(devm_register_power_off_handler); 517 518 /** 519 * devm_register_restart_handler - Register restart handler 520 * @dev: Device that registers callback 521 * @callback: Callback function 522 * @cb_data: Callback's argument 523 * 524 * Registers resource-managed sys-off handler with a default priority 525 * and using restart mode. 526 * 527 * Returns zero on success, or error code on failure. 528 */ 529 int devm_register_restart_handler(struct device *dev, 530 int (*callback)(struct sys_off_data *data), 531 void *cb_data) 532 { 533 return devm_register_sys_off_handler(dev, 534 SYS_OFF_MODE_RESTART, 535 SYS_OFF_PRIO_DEFAULT, 536 callback, cb_data); 537 } 538 EXPORT_SYMBOL_GPL(devm_register_restart_handler); 539 540 static struct sys_off_handler *platform_power_off_handler; 541 542 static int platform_power_off_notify(struct sys_off_data *data) 543 { 544 void (*platform_power_power_off_cb)(void) = data->cb_data; 545 546 platform_power_power_off_cb(); 547 548 return NOTIFY_DONE; 549 } 550 551 /** 552 * register_platform_power_off - Register platform-level power-off callback 553 * @power_off: Power-off callback 554 * 555 * Registers power-off callback that will be called as last step 556 * of the power-off sequence. This callback is expected to be invoked 557 * for the last resort. Only one platform power-off callback is allowed 558 * to be registered at a time. 559 * 560 * Returns zero on success, or error code on failure. 561 */ 562 int register_platform_power_off(void (*power_off)(void)) 563 { 564 struct sys_off_handler *handler; 565 566 handler = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, 567 SYS_OFF_PRIO_PLATFORM, 568 platform_power_off_notify, 569 power_off); 570 if (IS_ERR(handler)) 571 return PTR_ERR(handler); 572 573 platform_power_off_handler = handler; 574 575 return 0; 576 } 577 EXPORT_SYMBOL_GPL(register_platform_power_off); 578 579 /** 580 * unregister_platform_power_off - Unregister platform-level power-off callback 581 * @power_off: Power-off callback 582 * 583 * Unregisters previously registered platform power-off callback. 584 */ 585 void unregister_platform_power_off(void (*power_off)(void)) 586 { 587 if (platform_power_off_handler && 588 platform_power_off_handler->cb_data == power_off) { 589 unregister_sys_off_handler(platform_power_off_handler); 590 platform_power_off_handler = NULL; 591 } 592 } 593 EXPORT_SYMBOL_GPL(unregister_platform_power_off); 594 595 static int legacy_pm_power_off(struct sys_off_data *data) 596 { 597 if (pm_power_off) 598 pm_power_off(); 599 600 return NOTIFY_DONE; 601 } 602 603 static void do_kernel_power_off_prepare(void) 604 { 605 blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL); 606 } 607 608 /** 609 * do_kernel_power_off - Execute kernel power-off handler call chain 610 * 611 * Expected to be called as last step of the power-off sequence. 612 * 613 * Powers off the system immediately if a power-off handler function has 614 * been registered. Otherwise does nothing. 615 */ 616 void do_kernel_power_off(void) 617 { 618 atomic_notifier_call_chain(&power_off_handler_list, 0, NULL); 619 } 620 621 /** 622 * kernel_can_power_off - check whether system can be powered off 623 * 624 * Returns true if power-off handler is registered and system can be 625 * powered off, false otherwise. 626 */ 627 bool kernel_can_power_off(void) 628 { 629 return !atomic_notifier_call_chain_is_empty(&power_off_handler_list); 630 } 631 EXPORT_SYMBOL_GPL(kernel_can_power_off); 632 633 /** 634 * kernel_power_off - power_off the system 635 * 636 * Shutdown everything and perform a clean system power_off. 637 */ 638 void kernel_power_off(void) 639 { 640 kernel_shutdown_prepare(SYSTEM_POWER_OFF); 641 do_kernel_power_off_prepare(); 642 migrate_to_reboot_cpu(); 643 syscore_shutdown(); 644 pr_emerg("Power down\n"); 645 kmsg_dump(KMSG_DUMP_SHUTDOWN); 646 machine_power_off(); 647 } 648 EXPORT_SYMBOL_GPL(kernel_power_off); 649 650 DEFINE_MUTEX(system_transition_mutex); 651 652 /* 653 * Reboot system call: for obvious reasons only root may call it, 654 * and even root needs to set up some magic numbers in the registers 655 * so that some mistake won't make this reboot the whole machine. 656 * You can also set the meaning of the ctrl-alt-del-key here. 657 * 658 * reboot doesn't sync: do that yourself before calling this. 659 */ 660 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, 661 void __user *, arg) 662 { 663 struct pid_namespace *pid_ns = task_active_pid_ns(current); 664 struct sys_off_handler *sys_off = NULL; 665 char buffer[256]; 666 int ret = 0; 667 668 /* We only trust the superuser with rebooting the system. */ 669 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT)) 670 return -EPERM; 671 672 /* For safety, we require "magic" arguments. */ 673 if (magic1 != LINUX_REBOOT_MAGIC1 || 674 (magic2 != LINUX_REBOOT_MAGIC2 && 675 magic2 != LINUX_REBOOT_MAGIC2A && 676 magic2 != LINUX_REBOOT_MAGIC2B && 677 magic2 != LINUX_REBOOT_MAGIC2C)) 678 return -EINVAL; 679 680 /* 681 * If pid namespaces are enabled and the current task is in a child 682 * pid_namespace, the command is handled by reboot_pid_ns() which will 683 * call do_exit(). 684 */ 685 ret = reboot_pid_ns(pid_ns, cmd); 686 if (ret) 687 return ret; 688 689 /* 690 * Register sys-off handlers for legacy PM callback. This allows 691 * legacy PM callbacks temporary co-exist with the new sys-off API. 692 * 693 * TODO: Remove legacy handlers once all legacy PM users will be 694 * switched to the sys-off based APIs. 695 */ 696 if (pm_power_off) { 697 sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, 698 SYS_OFF_PRIO_DEFAULT, 699 legacy_pm_power_off, NULL); 700 if (IS_ERR(sys_off)) 701 return PTR_ERR(sys_off); 702 } 703 704 /* Instead of trying to make the power_off code look like 705 * halt when pm_power_off is not set do it the easy way. 706 */ 707 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off()) 708 cmd = LINUX_REBOOT_CMD_HALT; 709 710 mutex_lock(&system_transition_mutex); 711 switch (cmd) { 712 case LINUX_REBOOT_CMD_RESTART: 713 kernel_restart(NULL); 714 break; 715 716 case LINUX_REBOOT_CMD_CAD_ON: 717 C_A_D = 1; 718 break; 719 720 case LINUX_REBOOT_CMD_CAD_OFF: 721 C_A_D = 0; 722 break; 723 724 case LINUX_REBOOT_CMD_HALT: 725 kernel_halt(); 726 do_exit(0); 727 728 case LINUX_REBOOT_CMD_POWER_OFF: 729 kernel_power_off(); 730 do_exit(0); 731 break; 732 733 case LINUX_REBOOT_CMD_RESTART2: 734 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1); 735 if (ret < 0) { 736 ret = -EFAULT; 737 break; 738 } 739 buffer[sizeof(buffer) - 1] = '\0'; 740 741 kernel_restart(buffer); 742 break; 743 744 #ifdef CONFIG_KEXEC_CORE 745 case LINUX_REBOOT_CMD_KEXEC: 746 ret = kernel_kexec(); 747 break; 748 #endif 749 750 #ifdef CONFIG_HIBERNATION 751 case LINUX_REBOOT_CMD_SW_SUSPEND: 752 ret = hibernate(); 753 break; 754 #endif 755 756 default: 757 ret = -EINVAL; 758 break; 759 } 760 mutex_unlock(&system_transition_mutex); 761 unregister_sys_off_handler(sys_off); 762 return ret; 763 } 764 765 static void deferred_cad(struct work_struct *dummy) 766 { 767 kernel_restart(NULL); 768 } 769 770 /* 771 * This function gets called by ctrl-alt-del - ie the keyboard interrupt. 772 * As it's called within an interrupt, it may NOT sync: the only choice 773 * is whether to reboot at once, or just ignore the ctrl-alt-del. 774 */ 775 void ctrl_alt_del(void) 776 { 777 static DECLARE_WORK(cad_work, deferred_cad); 778 779 if (C_A_D) 780 schedule_work(&cad_work); 781 else 782 kill_cad_pid(SIGINT, 1); 783 } 784 785 #define POWEROFF_CMD_PATH_LEN 256 786 static char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff"; 787 static const char reboot_cmd[] = "/sbin/reboot"; 788 789 static int run_cmd(const char *cmd) 790 { 791 char **argv; 792 static char *envp[] = { 793 "HOME=/", 794 "PATH=/sbin:/bin:/usr/sbin:/usr/bin", 795 NULL 796 }; 797 int ret; 798 argv = argv_split(GFP_KERNEL, cmd, NULL); 799 if (argv) { 800 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); 801 argv_free(argv); 802 } else { 803 ret = -ENOMEM; 804 } 805 806 return ret; 807 } 808 809 static int __orderly_reboot(void) 810 { 811 int ret; 812 813 ret = run_cmd(reboot_cmd); 814 815 if (ret) { 816 printk_prefer_direct_enter(); 817 pr_warn("Failed to start orderly reboot: forcing the issue\n"); 818 emergency_sync(); 819 kernel_restart(NULL); 820 printk_prefer_direct_exit(); 821 } 822 823 return ret; 824 } 825 826 static int __orderly_poweroff(bool force) 827 { 828 int ret; 829 830 ret = run_cmd(poweroff_cmd); 831 832 if (ret && force) { 833 printk_prefer_direct_enter(); 834 pr_warn("Failed to start orderly shutdown: forcing the issue\n"); 835 836 /* 837 * I guess this should try to kick off some daemon to sync and 838 * poweroff asap. Or not even bother syncing if we're doing an 839 * emergency shutdown? 840 */ 841 emergency_sync(); 842 kernel_power_off(); 843 printk_prefer_direct_exit(); 844 } 845 846 return ret; 847 } 848 849 static bool poweroff_force; 850 851 static void poweroff_work_func(struct work_struct *work) 852 { 853 __orderly_poweroff(poweroff_force); 854 } 855 856 static DECLARE_WORK(poweroff_work, poweroff_work_func); 857 858 /** 859 * orderly_poweroff - Trigger an orderly system poweroff 860 * @force: force poweroff if command execution fails 861 * 862 * This may be called from any context to trigger a system shutdown. 863 * If the orderly shutdown fails, it will force an immediate shutdown. 864 */ 865 void orderly_poweroff(bool force) 866 { 867 if (force) /* do not override the pending "true" */ 868 poweroff_force = true; 869 schedule_work(&poweroff_work); 870 } 871 EXPORT_SYMBOL_GPL(orderly_poweroff); 872 873 static void reboot_work_func(struct work_struct *work) 874 { 875 __orderly_reboot(); 876 } 877 878 static DECLARE_WORK(reboot_work, reboot_work_func); 879 880 /** 881 * orderly_reboot - Trigger an orderly system reboot 882 * 883 * This may be called from any context to trigger a system reboot. 884 * If the orderly reboot fails, it will force an immediate reboot. 885 */ 886 void orderly_reboot(void) 887 { 888 schedule_work(&reboot_work); 889 } 890 EXPORT_SYMBOL_GPL(orderly_reboot); 891 892 /** 893 * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay 894 * @work: work_struct associated with the emergency poweroff function 895 * 896 * This function is called in very critical situations to force 897 * a kernel poweroff after a configurable timeout value. 898 */ 899 static void hw_failure_emergency_poweroff_func(struct work_struct *work) 900 { 901 printk_prefer_direct_enter(); 902 903 /* 904 * We have reached here after the emergency shutdown waiting period has 905 * expired. This means orderly_poweroff has not been able to shut off 906 * the system for some reason. 907 * 908 * Try to shut down the system immediately using kernel_power_off 909 * if populated 910 */ 911 pr_emerg("Hardware protection timed-out. Trying forced poweroff\n"); 912 kernel_power_off(); 913 914 /* 915 * Worst of the worst case trigger emergency restart 916 */ 917 pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n"); 918 emergency_restart(); 919 920 printk_prefer_direct_exit(); 921 } 922 923 static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work, 924 hw_failure_emergency_poweroff_func); 925 926 /** 927 * hw_failure_emergency_poweroff - Trigger an emergency system poweroff 928 * 929 * This may be called from any critical situation to trigger a system shutdown 930 * after a given period of time. If time is negative this is not scheduled. 931 */ 932 static void hw_failure_emergency_poweroff(int poweroff_delay_ms) 933 { 934 if (poweroff_delay_ms <= 0) 935 return; 936 schedule_delayed_work(&hw_failure_emergency_poweroff_work, 937 msecs_to_jiffies(poweroff_delay_ms)); 938 } 939 940 /** 941 * hw_protection_shutdown - Trigger an emergency system poweroff 942 * 943 * @reason: Reason of emergency shutdown to be printed. 944 * @ms_until_forced: Time to wait for orderly shutdown before tiggering a 945 * forced shudown. Negative value disables the forced 946 * shutdown. 947 * 948 * Initiate an emergency system shutdown in order to protect hardware from 949 * further damage. Usage examples include a thermal protection or a voltage or 950 * current regulator failures. 951 * NOTE: The request is ignored if protection shutdown is already pending even 952 * if the previous request has given a large timeout for forced shutdown. 953 * Can be called from any context. 954 */ 955 void hw_protection_shutdown(const char *reason, int ms_until_forced) 956 { 957 static atomic_t allow_proceed = ATOMIC_INIT(1); 958 959 printk_prefer_direct_enter(); 960 961 pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason); 962 963 /* Shutdown should be initiated only once. */ 964 if (!atomic_dec_and_test(&allow_proceed)) 965 goto out; 966 967 /* 968 * Queue a backup emergency shutdown in the event of 969 * orderly_poweroff failure 970 */ 971 hw_failure_emergency_poweroff(ms_until_forced); 972 orderly_poweroff(true); 973 out: 974 printk_prefer_direct_exit(); 975 } 976 EXPORT_SYMBOL_GPL(hw_protection_shutdown); 977 978 static int __init reboot_setup(char *str) 979 { 980 for (;;) { 981 enum reboot_mode *mode; 982 983 /* 984 * Having anything passed on the command line via 985 * reboot= will cause us to disable DMI checking 986 * below. 987 */ 988 reboot_default = 0; 989 990 if (!strncmp(str, "panic_", 6)) { 991 mode = &panic_reboot_mode; 992 str += 6; 993 } else { 994 mode = &reboot_mode; 995 } 996 997 switch (*str) { 998 case 'w': 999 *mode = REBOOT_WARM; 1000 break; 1001 1002 case 'c': 1003 *mode = REBOOT_COLD; 1004 break; 1005 1006 case 'h': 1007 *mode = REBOOT_HARD; 1008 break; 1009 1010 case 's': 1011 /* 1012 * reboot_cpu is s[mp]#### with #### being the processor 1013 * to be used for rebooting. Skip 's' or 'smp' prefix. 1014 */ 1015 str += str[1] == 'm' && str[2] == 'p' ? 3 : 1; 1016 1017 if (isdigit(str[0])) { 1018 int cpu = simple_strtoul(str, NULL, 0); 1019 1020 if (cpu >= num_possible_cpus()) { 1021 pr_err("Ignoring the CPU number in reboot= option. " 1022 "CPU %d exceeds possible cpu number %d\n", 1023 cpu, num_possible_cpus()); 1024 break; 1025 } 1026 reboot_cpu = cpu; 1027 } else 1028 *mode = REBOOT_SOFT; 1029 break; 1030 1031 case 'g': 1032 *mode = REBOOT_GPIO; 1033 break; 1034 1035 case 'b': 1036 case 'a': 1037 case 'k': 1038 case 't': 1039 case 'e': 1040 case 'p': 1041 reboot_type = *str; 1042 break; 1043 1044 case 'f': 1045 reboot_force = 1; 1046 break; 1047 } 1048 1049 str = strchr(str, ','); 1050 if (str) 1051 str++; 1052 else 1053 break; 1054 } 1055 return 1; 1056 } 1057 __setup("reboot=", reboot_setup); 1058 1059 #ifdef CONFIG_SYSFS 1060 1061 #define REBOOT_COLD_STR "cold" 1062 #define REBOOT_WARM_STR "warm" 1063 #define REBOOT_HARD_STR "hard" 1064 #define REBOOT_SOFT_STR "soft" 1065 #define REBOOT_GPIO_STR "gpio" 1066 #define REBOOT_UNDEFINED_STR "undefined" 1067 1068 #define BOOT_TRIPLE_STR "triple" 1069 #define BOOT_KBD_STR "kbd" 1070 #define BOOT_BIOS_STR "bios" 1071 #define BOOT_ACPI_STR "acpi" 1072 #define BOOT_EFI_STR "efi" 1073 #define BOOT_PCI_STR "pci" 1074 1075 static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1076 { 1077 const char *val; 1078 1079 switch (reboot_mode) { 1080 case REBOOT_COLD: 1081 val = REBOOT_COLD_STR; 1082 break; 1083 case REBOOT_WARM: 1084 val = REBOOT_WARM_STR; 1085 break; 1086 case REBOOT_HARD: 1087 val = REBOOT_HARD_STR; 1088 break; 1089 case REBOOT_SOFT: 1090 val = REBOOT_SOFT_STR; 1091 break; 1092 case REBOOT_GPIO: 1093 val = REBOOT_GPIO_STR; 1094 break; 1095 default: 1096 val = REBOOT_UNDEFINED_STR; 1097 } 1098 1099 return sprintf(buf, "%s\n", val); 1100 } 1101 static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr, 1102 const char *buf, size_t count) 1103 { 1104 if (!capable(CAP_SYS_BOOT)) 1105 return -EPERM; 1106 1107 if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR))) 1108 reboot_mode = REBOOT_COLD; 1109 else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR))) 1110 reboot_mode = REBOOT_WARM; 1111 else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR))) 1112 reboot_mode = REBOOT_HARD; 1113 else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR))) 1114 reboot_mode = REBOOT_SOFT; 1115 else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR))) 1116 reboot_mode = REBOOT_GPIO; 1117 else 1118 return -EINVAL; 1119 1120 reboot_default = 0; 1121 1122 return count; 1123 } 1124 static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode); 1125 1126 #ifdef CONFIG_X86 1127 static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1128 { 1129 return sprintf(buf, "%d\n", reboot_force); 1130 } 1131 static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, 1132 const char *buf, size_t count) 1133 { 1134 bool res; 1135 1136 if (!capable(CAP_SYS_BOOT)) 1137 return -EPERM; 1138 1139 if (kstrtobool(buf, &res)) 1140 return -EINVAL; 1141 1142 reboot_default = 0; 1143 reboot_force = res; 1144 1145 return count; 1146 } 1147 static struct kobj_attribute reboot_force_attr = __ATTR_RW(force); 1148 1149 static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1150 { 1151 const char *val; 1152 1153 switch (reboot_type) { 1154 case BOOT_TRIPLE: 1155 val = BOOT_TRIPLE_STR; 1156 break; 1157 case BOOT_KBD: 1158 val = BOOT_KBD_STR; 1159 break; 1160 case BOOT_BIOS: 1161 val = BOOT_BIOS_STR; 1162 break; 1163 case BOOT_ACPI: 1164 val = BOOT_ACPI_STR; 1165 break; 1166 case BOOT_EFI: 1167 val = BOOT_EFI_STR; 1168 break; 1169 case BOOT_CF9_FORCE: 1170 val = BOOT_PCI_STR; 1171 break; 1172 default: 1173 val = REBOOT_UNDEFINED_STR; 1174 } 1175 1176 return sprintf(buf, "%s\n", val); 1177 } 1178 static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr, 1179 const char *buf, size_t count) 1180 { 1181 if (!capable(CAP_SYS_BOOT)) 1182 return -EPERM; 1183 1184 if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR))) 1185 reboot_type = BOOT_TRIPLE; 1186 else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR))) 1187 reboot_type = BOOT_KBD; 1188 else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR))) 1189 reboot_type = BOOT_BIOS; 1190 else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR))) 1191 reboot_type = BOOT_ACPI; 1192 else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR))) 1193 reboot_type = BOOT_EFI; 1194 else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR))) 1195 reboot_type = BOOT_CF9_FORCE; 1196 else 1197 return -EINVAL; 1198 1199 reboot_default = 0; 1200 1201 return count; 1202 } 1203 static struct kobj_attribute reboot_type_attr = __ATTR_RW(type); 1204 #endif 1205 1206 #ifdef CONFIG_SMP 1207 static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1208 { 1209 return sprintf(buf, "%d\n", reboot_cpu); 1210 } 1211 static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr, 1212 const char *buf, size_t count) 1213 { 1214 unsigned int cpunum; 1215 int rc; 1216 1217 if (!capable(CAP_SYS_BOOT)) 1218 return -EPERM; 1219 1220 rc = kstrtouint(buf, 0, &cpunum); 1221 1222 if (rc) 1223 return rc; 1224 1225 if (cpunum >= num_possible_cpus()) 1226 return -ERANGE; 1227 1228 reboot_default = 0; 1229 reboot_cpu = cpunum; 1230 1231 return count; 1232 } 1233 static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu); 1234 #endif 1235 1236 static struct attribute *reboot_attrs[] = { 1237 &reboot_mode_attr.attr, 1238 #ifdef CONFIG_X86 1239 &reboot_force_attr.attr, 1240 &reboot_type_attr.attr, 1241 #endif 1242 #ifdef CONFIG_SMP 1243 &reboot_cpu_attr.attr, 1244 #endif 1245 NULL, 1246 }; 1247 1248 #ifdef CONFIG_SYSCTL 1249 static struct ctl_table kern_reboot_table[] = { 1250 { 1251 .procname = "poweroff_cmd", 1252 .data = &poweroff_cmd, 1253 .maxlen = POWEROFF_CMD_PATH_LEN, 1254 .mode = 0644, 1255 .proc_handler = proc_dostring, 1256 }, 1257 { 1258 .procname = "ctrl-alt-del", 1259 .data = &C_A_D, 1260 .maxlen = sizeof(int), 1261 .mode = 0644, 1262 .proc_handler = proc_dointvec, 1263 }, 1264 { } 1265 }; 1266 1267 static void __init kernel_reboot_sysctls_init(void) 1268 { 1269 register_sysctl_init("kernel", kern_reboot_table); 1270 } 1271 #else 1272 #define kernel_reboot_sysctls_init() do { } while (0) 1273 #endif /* CONFIG_SYSCTL */ 1274 1275 static const struct attribute_group reboot_attr_group = { 1276 .attrs = reboot_attrs, 1277 }; 1278 1279 static int __init reboot_ksysfs_init(void) 1280 { 1281 struct kobject *reboot_kobj; 1282 int ret; 1283 1284 reboot_kobj = kobject_create_and_add("reboot", kernel_kobj); 1285 if (!reboot_kobj) 1286 return -ENOMEM; 1287 1288 ret = sysfs_create_group(reboot_kobj, &reboot_attr_group); 1289 if (ret) { 1290 kobject_put(reboot_kobj); 1291 return ret; 1292 } 1293 1294 kernel_reboot_sysctls_init(); 1295 1296 return 0; 1297 } 1298 late_initcall(reboot_ksysfs_init); 1299 1300 #endif 1301