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 26static int C_A_D = 1; 27struct pid *cad_pid; 28EXPORT_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 35enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE; 36EXPORT_SYMBOL_GPL(reboot_mode); 37enum 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 */ 46int reboot_default = 1; 47int reboot_cpu; 48enum reboot_type reboot_type = BOOT_ACPI; 49int reboot_force; 50 51struct 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 struct device *dev; 59}; 60 61/* 62 * This variable is used to indicate if a halt was initiated instead of a 63 * reboot when the reboot call was invoked with LINUX_REBOOT_CMD_POWER_OFF, but 64 * the system cannot be powered off. This allowes kernel_halt() to notify users 65 * of that. 66 */ 67static bool poweroff_fallback_to_halt; 68 69/* 70 * Temporary stub that prevents linkage failure while we're in process 71 * of removing all uses of legacy pm_power_off() around the kernel. 72 */ 73void __weak (*pm_power_off)(void); 74 75/** 76 * emergency_restart - reboot the system 77 * 78 * Without shutting down any hardware or taking any locks 79 * reboot the system. This is called when we know we are in 80 * trouble so this is our best effort to reboot. This is 81 * safe to call in interrupt context. 82 */ 83void emergency_restart(void) 84{ 85 kmsg_dump(KMSG_DUMP_EMERG); 86 system_state = SYSTEM_RESTART; 87 machine_emergency_restart(); 88} 89EXPORT_SYMBOL_GPL(emergency_restart); 90 91void kernel_restart_prepare(char *cmd) 92{ 93 blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); 94 system_state = SYSTEM_RESTART; 95 usermodehelper_disable(); 96 device_shutdown(); 97} 98 99/** 100 * register_reboot_notifier - Register function to be called at reboot time 101 * @nb: Info about notifier function to be called 102 * 103 * Registers a function with the list of functions 104 * to be called at reboot time. 105 * 106 * Currently always returns zero, as blocking_notifier_chain_register() 107 * always returns zero. 108 */ 109int register_reboot_notifier(struct notifier_block *nb) 110{ 111 return blocking_notifier_chain_register(&reboot_notifier_list, nb); 112} 113EXPORT_SYMBOL(register_reboot_notifier); 114 115/** 116 * unregister_reboot_notifier - Unregister previously registered reboot notifier 117 * @nb: Hook to be unregistered 118 * 119 * Unregisters a previously registered reboot 120 * notifier function. 121 * 122 * Returns zero on success, or %-ENOENT on failure. 123 */ 124int unregister_reboot_notifier(struct notifier_block *nb) 125{ 126 return blocking_notifier_chain_unregister(&reboot_notifier_list, nb); 127} 128EXPORT_SYMBOL(unregister_reboot_notifier); 129 130static void devm_unregister_reboot_notifier(struct device *dev, void *res) 131{ 132 WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res)); 133} 134 135int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb) 136{ 137 struct notifier_block **rcnb; 138 int ret; 139 140 rcnb = devres_alloc(devm_unregister_reboot_notifier, 141 sizeof(*rcnb), GFP_KERNEL); 142 if (!rcnb) 143 return -ENOMEM; 144 145 ret = register_reboot_notifier(nb); 146 if (!ret) { 147 *rcnb = nb; 148 devres_add(dev, rcnb); 149 } else { 150 devres_free(rcnb); 151 } 152 153 return ret; 154} 155EXPORT_SYMBOL(devm_register_reboot_notifier); 156 157/* 158 * Notifier list for kernel code which wants to be called 159 * to restart the system. 160 */ 161static ATOMIC_NOTIFIER_HEAD(restart_handler_list); 162 163/** 164 * register_restart_handler - Register function to be called to reset 165 * the system 166 * @nb: Info about handler function to be called 167 * @nb->priority: Handler priority. Handlers should follow the 168 * following guidelines for setting priorities. 169 * 0: Restart handler of last resort, 170 * with limited restart capabilities 171 * 128: Default restart handler; use if no other 172 * restart handler is expected to be available, 173 * and/or if restart functionality is 174 * sufficient to restart the entire system 175 * 255: Highest priority restart handler, will 176 * preempt all other restart handlers 177 * 178 * Registers a function with code to be called to restart the 179 * system. 180 * 181 * Registered functions will be called from machine_restart as last 182 * step of the restart sequence (if the architecture specific 183 * machine_restart function calls do_kernel_restart - see below 184 * for details). 185 * Registered functions are expected to restart the system immediately. 186 * If more than one function is registered, the restart handler priority 187 * selects which function will be called first. 188 * 189 * Restart handlers are expected to be registered from non-architecture 190 * code, typically from drivers. A typical use case would be a system 191 * where restart functionality is provided through a watchdog. Multiple 192 * restart handlers may exist; for example, one restart handler might 193 * restart the entire system, while another only restarts the CPU. 194 * In such cases, the restart handler which only restarts part of the 195 * hardware is expected to register with low priority to ensure that 196 * it only runs if no other means to restart the system is available. 197 * 198 * Currently always returns zero, as atomic_notifier_chain_register() 199 * always returns zero. 200 */ 201int register_restart_handler(struct notifier_block *nb) 202{ 203 return atomic_notifier_chain_register(&restart_handler_list, nb); 204} 205EXPORT_SYMBOL(register_restart_handler); 206 207/** 208 * unregister_restart_handler - Unregister previously registered 209 * restart handler 210 * @nb: Hook to be unregistered 211 * 212 * Unregisters a previously registered restart handler function. 213 * 214 * Returns zero on success, or %-ENOENT on failure. 215 */ 216int unregister_restart_handler(struct notifier_block *nb) 217{ 218 return atomic_notifier_chain_unregister(&restart_handler_list, nb); 219} 220EXPORT_SYMBOL(unregister_restart_handler); 221 222/** 223 * do_kernel_restart - Execute kernel restart handler call chain 224 * 225 * Calls functions registered with register_restart_handler. 226 * 227 * Expected to be called from machine_restart as last step of the restart 228 * sequence. 229 * 230 * Restarts the system immediately if a restart handler function has been 231 * registered. Otherwise does nothing. 232 */ 233void do_kernel_restart(char *cmd) 234{ 235 atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd); 236} 237 238void migrate_to_reboot_cpu(void) 239{ 240 /* The boot cpu is always logical cpu 0 */ 241 int cpu = reboot_cpu; 242 243 cpu_hotplug_disable(); 244 245 /* Make certain the cpu I'm about to reboot on is online */ 246 if (!cpu_online(cpu)) 247 cpu = cpumask_first(cpu_online_mask); 248 249 /* Prevent races with other tasks migrating this task */ 250 current->flags |= PF_NO_SETAFFINITY; 251 252 /* Make certain I only run on the appropriate processor */ 253 set_cpus_allowed_ptr(current, cpumask_of(cpu)); 254} 255 256/* 257 * Notifier list for kernel code which wants to be called 258 * to prepare system for restart. 259 */ 260static BLOCKING_NOTIFIER_HEAD(restart_prep_handler_list); 261 262static void do_kernel_restart_prepare(void) 263{ 264 blocking_notifier_call_chain(&restart_prep_handler_list, 0, NULL); 265} 266 267/** 268 * kernel_restart - reboot the system 269 * @cmd: pointer to buffer containing command to execute for restart 270 * or %NULL 271 * 272 * Shutdown everything and perform a clean reboot. 273 * This is not safe to call in interrupt context. 274 */ 275void kernel_restart(char *cmd) 276{ 277 kernel_restart_prepare(cmd); 278 do_kernel_restart_prepare(); 279 migrate_to_reboot_cpu(); 280 syscore_shutdown(); 281 if (!cmd) 282 pr_emerg("Restarting system\n"); 283 else 284 pr_emerg("Restarting system with command '%s'\n", cmd); 285 kmsg_dump(KMSG_DUMP_SHUTDOWN); 286 machine_restart(cmd); 287} 288EXPORT_SYMBOL_GPL(kernel_restart); 289 290static void kernel_shutdown_prepare(enum system_states state) 291{ 292 blocking_notifier_call_chain(&reboot_notifier_list, 293 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL); 294 system_state = state; 295 usermodehelper_disable(); 296 device_shutdown(); 297} 298/** 299 * kernel_halt - halt the system 300 * 301 * Shutdown everything and perform a clean system halt. 302 */ 303void kernel_halt(void) 304{ 305 kernel_shutdown_prepare(SYSTEM_HALT); 306 migrate_to_reboot_cpu(); 307 syscore_shutdown(); 308 if (poweroff_fallback_to_halt) 309 pr_emerg("Power off not available: System halted instead\n"); 310 else 311 pr_emerg("System halted\n"); 312 kmsg_dump(KMSG_DUMP_SHUTDOWN); 313 machine_halt(); 314} 315EXPORT_SYMBOL_GPL(kernel_halt); 316 317/* 318 * Notifier list for kernel code which wants to be called 319 * to prepare system for power off. 320 */ 321static BLOCKING_NOTIFIER_HEAD(power_off_prep_handler_list); 322 323/* 324 * Notifier list for kernel code which wants to be called 325 * to power off system. 326 */ 327static ATOMIC_NOTIFIER_HEAD(power_off_handler_list); 328 329static int sys_off_notify(struct notifier_block *nb, 330 unsigned long mode, void *cmd) 331{ 332 struct sys_off_handler *handler; 333 struct sys_off_data data = {}; 334 335 handler = container_of(nb, struct sys_off_handler, nb); 336 data.cb_data = handler->cb_data; 337 data.mode = mode; 338 data.cmd = cmd; 339 data.dev = handler->dev; 340 341 return handler->sys_off_cb(&data); 342} 343 344static struct sys_off_handler platform_sys_off_handler; 345 346static struct sys_off_handler *alloc_sys_off_handler(int priority) 347{ 348 struct sys_off_handler *handler; 349 gfp_t flags; 350 351 /* 352 * Platforms like m68k can't allocate sys_off handler dynamically 353 * at the early boot time because memory allocator isn't available yet. 354 */ 355 if (priority == SYS_OFF_PRIO_PLATFORM) { 356 handler = &platform_sys_off_handler; 357 if (handler->cb_data) 358 return ERR_PTR(-EBUSY); 359 } else { 360 if (system_state > SYSTEM_RUNNING) 361 flags = GFP_ATOMIC; 362 else 363 flags = GFP_KERNEL; 364 365 handler = kzalloc(sizeof(*handler), flags); 366 if (!handler) 367 return ERR_PTR(-ENOMEM); 368 } 369 370 return handler; 371} 372 373static void free_sys_off_handler(struct sys_off_handler *handler) 374{ 375 if (handler == &platform_sys_off_handler) 376 memset(handler, 0, sizeof(*handler)); 377 else 378 kfree(handler); 379} 380 381/** 382 * register_sys_off_handler - Register sys-off handler 383 * @mode: Sys-off mode 384 * @priority: Handler priority 385 * @callback: Callback function 386 * @cb_data: Callback argument 387 * 388 * Registers system power-off or restart handler that will be invoked 389 * at the step corresponding to the given sys-off mode. Handler's callback 390 * should return NOTIFY_DONE to permit execution of the next handler in 391 * the call chain or NOTIFY_STOP to break the chain (in error case for 392 * example). 393 * 394 * Multiple handlers can be registered at the default priority level. 395 * 396 * Only one handler can be registered at the non-default priority level, 397 * otherwise ERR_PTR(-EBUSY) is returned. 398 * 399 * Returns a new instance of struct sys_off_handler on success, or 400 * an ERR_PTR()-encoded error code otherwise. 401 */ 402struct sys_off_handler * 403register_sys_off_handler(enum sys_off_mode mode, 404 int priority, 405 int (*callback)(struct sys_off_data *data), 406 void *cb_data) 407{ 408 struct sys_off_handler *handler; 409 int err; 410 411 handler = alloc_sys_off_handler(priority); 412 if (IS_ERR(handler)) 413 return handler; 414 415 switch (mode) { 416 case SYS_OFF_MODE_POWER_OFF_PREPARE: 417 handler->list = &power_off_prep_handler_list; 418 handler->blocking = true; 419 break; 420 421 case SYS_OFF_MODE_POWER_OFF: 422 handler->list = &power_off_handler_list; 423 break; 424 425 case SYS_OFF_MODE_RESTART_PREPARE: 426 handler->list = &restart_prep_handler_list; 427 handler->blocking = true; 428 break; 429 430 case SYS_OFF_MODE_RESTART: 431 handler->list = &restart_handler_list; 432 break; 433 434 default: 435 free_sys_off_handler(handler); 436 return ERR_PTR(-EINVAL); 437 } 438 439 handler->nb.notifier_call = sys_off_notify; 440 handler->nb.priority = priority; 441 handler->sys_off_cb = callback; 442 handler->cb_data = cb_data; 443 handler->mode = mode; 444 445 if (handler->blocking) { 446 if (priority == SYS_OFF_PRIO_DEFAULT) 447 err = blocking_notifier_chain_register(handler->list, 448 &handler->nb); 449 else 450 err = blocking_notifier_chain_register_unique_prio(handler->list, 451 &handler->nb); 452 } else { 453 if (priority == SYS_OFF_PRIO_DEFAULT) 454 err = atomic_notifier_chain_register(handler->list, 455 &handler->nb); 456 else 457 err = atomic_notifier_chain_register_unique_prio(handler->list, 458 &handler->nb); 459 } 460 461 if (err) { 462 free_sys_off_handler(handler); 463 return ERR_PTR(err); 464 } 465 466 return handler; 467} 468EXPORT_SYMBOL_GPL(register_sys_off_handler); 469 470/** 471 * unregister_sys_off_handler - Unregister sys-off handler 472 * @handler: Sys-off handler 473 * 474 * Unregisters given sys-off handler. 475 */ 476void unregister_sys_off_handler(struct sys_off_handler *handler) 477{ 478 int err; 479 480 if (IS_ERR_OR_NULL(handler)) 481 return; 482 483 if (handler->blocking) 484 err = blocking_notifier_chain_unregister(handler->list, 485 &handler->nb); 486 else 487 err = atomic_notifier_chain_unregister(handler->list, 488 &handler->nb); 489 490 /* sanity check, shall never happen */ 491 WARN_ON(err); 492 493 free_sys_off_handler(handler); 494} 495EXPORT_SYMBOL_GPL(unregister_sys_off_handler); 496 497static void devm_unregister_sys_off_handler(void *data) 498{ 499 struct sys_off_handler *handler = data; 500 501 unregister_sys_off_handler(handler); 502} 503 504/** 505 * devm_register_sys_off_handler - Register sys-off handler 506 * @dev: Device that registers handler 507 * @mode: Sys-off mode 508 * @priority: Handler priority 509 * @callback: Callback function 510 * @cb_data: Callback argument 511 * 512 * Registers resource-managed sys-off handler. 513 * 514 * Returns zero on success, or error code on failure. 515 */ 516int devm_register_sys_off_handler(struct device *dev, 517 enum sys_off_mode mode, 518 int priority, 519 int (*callback)(struct sys_off_data *data), 520 void *cb_data) 521{ 522 struct sys_off_handler *handler; 523 524 handler = register_sys_off_handler(mode, priority, callback, cb_data); 525 if (IS_ERR(handler)) 526 return PTR_ERR(handler); 527 handler->dev = dev; 528 529 return devm_add_action_or_reset(dev, devm_unregister_sys_off_handler, 530 handler); 531} 532EXPORT_SYMBOL_GPL(devm_register_sys_off_handler); 533 534/** 535 * devm_register_power_off_handler - Register power-off handler 536 * @dev: Device that registers callback 537 * @callback: Callback function 538 * @cb_data: Callback's argument 539 * 540 * Registers resource-managed sys-off handler with a default priority 541 * and using power-off mode. 542 * 543 * Returns zero on success, or error code on failure. 544 */ 545int devm_register_power_off_handler(struct device *dev, 546 int (*callback)(struct sys_off_data *data), 547 void *cb_data) 548{ 549 return devm_register_sys_off_handler(dev, 550 SYS_OFF_MODE_POWER_OFF, 551 SYS_OFF_PRIO_DEFAULT, 552 callback, cb_data); 553} 554EXPORT_SYMBOL_GPL(devm_register_power_off_handler); 555 556/** 557 * devm_register_restart_handler - Register restart handler 558 * @dev: Device that registers callback 559 * @callback: Callback function 560 * @cb_data: Callback's argument 561 * 562 * Registers resource-managed sys-off handler with a default priority 563 * and using restart mode. 564 * 565 * Returns zero on success, or error code on failure. 566 */ 567int devm_register_restart_handler(struct device *dev, 568 int (*callback)(struct sys_off_data *data), 569 void *cb_data) 570{ 571 return devm_register_sys_off_handler(dev, 572 SYS_OFF_MODE_RESTART, 573 SYS_OFF_PRIO_DEFAULT, 574 callback, cb_data); 575} 576EXPORT_SYMBOL_GPL(devm_register_restart_handler); 577 578static struct sys_off_handler *platform_power_off_handler; 579 580static int platform_power_off_notify(struct sys_off_data *data) 581{ 582 void (*platform_power_power_off_cb)(void) = data->cb_data; 583 584 platform_power_power_off_cb(); 585 586 return NOTIFY_DONE; 587} 588 589/** 590 * register_platform_power_off - Register platform-level power-off callback 591 * @power_off: Power-off callback 592 * 593 * Registers power-off callback that will be called as last step 594 * of the power-off sequence. This callback is expected to be invoked 595 * for the last resort. Only one platform power-off callback is allowed 596 * to be registered at a time. 597 * 598 * Returns zero on success, or error code on failure. 599 */ 600int register_platform_power_off(void (*power_off)(void)) 601{ 602 struct sys_off_handler *handler; 603 604 handler = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, 605 SYS_OFF_PRIO_PLATFORM, 606 platform_power_off_notify, 607 power_off); 608 if (IS_ERR(handler)) 609 return PTR_ERR(handler); 610 611 platform_power_off_handler = handler; 612 613 return 0; 614} 615EXPORT_SYMBOL_GPL(register_platform_power_off); 616 617/** 618 * unregister_platform_power_off - Unregister platform-level power-off callback 619 * @power_off: Power-off callback 620 * 621 * Unregisters previously registered platform power-off callback. 622 */ 623void unregister_platform_power_off(void (*power_off)(void)) 624{ 625 if (platform_power_off_handler && 626 platform_power_off_handler->cb_data == power_off) { 627 unregister_sys_off_handler(platform_power_off_handler); 628 platform_power_off_handler = NULL; 629 } 630} 631EXPORT_SYMBOL_GPL(unregister_platform_power_off); 632 633static int legacy_pm_power_off(struct sys_off_data *data) 634{ 635 if (pm_power_off) 636 pm_power_off(); 637 638 return NOTIFY_DONE; 639} 640 641static void do_kernel_power_off_prepare(void) 642{ 643 blocking_notifier_call_chain(&power_off_prep_handler_list, 0, NULL); 644} 645 646/** 647 * do_kernel_power_off - Execute kernel power-off handler call chain 648 * 649 * Expected to be called as last step of the power-off sequence. 650 * 651 * Powers off the system immediately if a power-off handler function has 652 * been registered. Otherwise does nothing. 653 */ 654void do_kernel_power_off(void) 655{ 656 struct sys_off_handler *sys_off = NULL; 657 658 /* 659 * Register sys-off handlers for legacy PM callback. This allows 660 * legacy PM callbacks temporary co-exist with the new sys-off API. 661 * 662 * TODO: Remove legacy handlers once all legacy PM users will be 663 * switched to the sys-off based APIs. 664 */ 665 if (pm_power_off) 666 sys_off = register_sys_off_handler(SYS_OFF_MODE_POWER_OFF, 667 SYS_OFF_PRIO_DEFAULT, 668 legacy_pm_power_off, NULL); 669 670 atomic_notifier_call_chain(&power_off_handler_list, 0, NULL); 671 672 unregister_sys_off_handler(sys_off); 673} 674 675/** 676 * kernel_can_power_off - check whether system can be powered off 677 * 678 * Returns true if power-off handler is registered and system can be 679 * powered off, false otherwise. 680 */ 681bool kernel_can_power_off(void) 682{ 683 return !atomic_notifier_call_chain_is_empty(&power_off_handler_list) || 684 pm_power_off; 685} 686EXPORT_SYMBOL_GPL(kernel_can_power_off); 687 688/** 689 * kernel_power_off - power_off the system 690 * 691 * Shutdown everything and perform a clean system power_off. 692 */ 693void kernel_power_off(void) 694{ 695 kernel_shutdown_prepare(SYSTEM_POWER_OFF); 696 do_kernel_power_off_prepare(); 697 migrate_to_reboot_cpu(); 698 syscore_shutdown(); 699 pr_emerg("Power down\n"); 700 kmsg_dump(KMSG_DUMP_SHUTDOWN); 701 machine_power_off(); 702} 703EXPORT_SYMBOL_GPL(kernel_power_off); 704 705DEFINE_MUTEX(system_transition_mutex); 706 707/* 708 * Reboot system call: for obvious reasons only root may call it, 709 * and even root needs to set up some magic numbers in the registers 710 * so that some mistake won't make this reboot the whole machine. 711 * You can also set the meaning of the ctrl-alt-del-key here. 712 * 713 * reboot doesn't sync: do that yourself before calling this. 714 */ 715SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd, 716 void __user *, arg) 717{ 718 struct pid_namespace *pid_ns = task_active_pid_ns(current); 719 char buffer[256]; 720 int ret = 0; 721 722 /* We only trust the superuser with rebooting the system. */ 723 if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT)) 724 return -EPERM; 725 726 /* For safety, we require "magic" arguments. */ 727 if (magic1 != LINUX_REBOOT_MAGIC1 || 728 (magic2 != LINUX_REBOOT_MAGIC2 && 729 magic2 != LINUX_REBOOT_MAGIC2A && 730 magic2 != LINUX_REBOOT_MAGIC2B && 731 magic2 != LINUX_REBOOT_MAGIC2C)) 732 return -EINVAL; 733 734 /* 735 * If pid namespaces are enabled and the current task is in a child 736 * pid_namespace, the command is handled by reboot_pid_ns() which will 737 * call do_exit(). 738 */ 739 ret = reboot_pid_ns(pid_ns, cmd); 740 if (ret) 741 return ret; 742 743 /* Instead of trying to make the power_off code look like 744 * halt when pm_power_off is not set do it the easy way. 745 */ 746 if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off()) { 747 poweroff_fallback_to_halt = true; 748 cmd = LINUX_REBOOT_CMD_HALT; 749 } 750 751 mutex_lock(&system_transition_mutex); 752 switch (cmd) { 753 case LINUX_REBOOT_CMD_RESTART: 754 kernel_restart(NULL); 755 break; 756 757 case LINUX_REBOOT_CMD_CAD_ON: 758 C_A_D = 1; 759 break; 760 761 case LINUX_REBOOT_CMD_CAD_OFF: 762 C_A_D = 0; 763 break; 764 765 case LINUX_REBOOT_CMD_HALT: 766 kernel_halt(); 767 do_exit(0); 768 769 case LINUX_REBOOT_CMD_POWER_OFF: 770 kernel_power_off(); 771 do_exit(0); 772 break; 773 774 case LINUX_REBOOT_CMD_RESTART2: 775 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1); 776 if (ret < 0) { 777 ret = -EFAULT; 778 break; 779 } 780 buffer[sizeof(buffer) - 1] = '\0'; 781 782 kernel_restart(buffer); 783 break; 784 785#ifdef CONFIG_KEXEC_CORE 786 case LINUX_REBOOT_CMD_KEXEC: 787 ret = kernel_kexec(); 788 break; 789#endif 790 791#ifdef CONFIG_HIBERNATION 792 case LINUX_REBOOT_CMD_SW_SUSPEND: 793 ret = hibernate(); 794 break; 795#endif 796 797 default: 798 ret = -EINVAL; 799 break; 800 } 801 mutex_unlock(&system_transition_mutex); 802 return ret; 803} 804 805static void deferred_cad(struct work_struct *dummy) 806{ 807 kernel_restart(NULL); 808} 809 810/* 811 * This function gets called by ctrl-alt-del - ie the keyboard interrupt. 812 * As it's called within an interrupt, it may NOT sync: the only choice 813 * is whether to reboot at once, or just ignore the ctrl-alt-del. 814 */ 815void ctrl_alt_del(void) 816{ 817 static DECLARE_WORK(cad_work, deferred_cad); 818 819 if (C_A_D) 820 schedule_work(&cad_work); 821 else 822 kill_cad_pid(SIGINT, 1); 823} 824 825#define POWEROFF_CMD_PATH_LEN 256 826static char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff"; 827static const char reboot_cmd[] = "/sbin/reboot"; 828 829static int run_cmd(const char *cmd) 830{ 831 char **argv; 832 static char *envp[] = { 833 "HOME=/", 834 "PATH=/sbin:/bin:/usr/sbin:/usr/bin", 835 NULL 836 }; 837 int ret; 838 argv = argv_split(GFP_KERNEL, cmd, NULL); 839 if (argv) { 840 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); 841 argv_free(argv); 842 } else { 843 ret = -ENOMEM; 844 } 845 846 return ret; 847} 848 849static int __orderly_reboot(void) 850{ 851 int ret; 852 853 ret = run_cmd(reboot_cmd); 854 855 if (ret) { 856 pr_warn("Failed to start orderly reboot: forcing the issue\n"); 857 emergency_sync(); 858 kernel_restart(NULL); 859 } 860 861 return ret; 862} 863 864static int __orderly_poweroff(bool force) 865{ 866 int ret; 867 868 ret = run_cmd(poweroff_cmd); 869 870 if (ret && force) { 871 pr_warn("Failed to start orderly shutdown: forcing the issue\n"); 872 873 /* 874 * I guess this should try to kick off some daemon to sync and 875 * poweroff asap. Or not even bother syncing if we're doing an 876 * emergency shutdown? 877 */ 878 emergency_sync(); 879 kernel_power_off(); 880 } 881 882 return ret; 883} 884 885static bool poweroff_force; 886 887static void poweroff_work_func(struct work_struct *work) 888{ 889 __orderly_poweroff(poweroff_force); 890} 891 892static DECLARE_WORK(poweroff_work, poweroff_work_func); 893 894/** 895 * orderly_poweroff - Trigger an orderly system poweroff 896 * @force: force poweroff if command execution fails 897 * 898 * This may be called from any context to trigger a system shutdown. 899 * If the orderly shutdown fails, it will force an immediate shutdown. 900 */ 901void orderly_poweroff(bool force) 902{ 903 if (force) /* do not override the pending "true" */ 904 poweroff_force = true; 905 schedule_work(&poweroff_work); 906} 907EXPORT_SYMBOL_GPL(orderly_poweroff); 908 909static void reboot_work_func(struct work_struct *work) 910{ 911 __orderly_reboot(); 912} 913 914static DECLARE_WORK(reboot_work, reboot_work_func); 915 916/** 917 * orderly_reboot - Trigger an orderly system reboot 918 * 919 * This may be called from any context to trigger a system reboot. 920 * If the orderly reboot fails, it will force an immediate reboot. 921 */ 922void orderly_reboot(void) 923{ 924 schedule_work(&reboot_work); 925} 926EXPORT_SYMBOL_GPL(orderly_reboot); 927 928/** 929 * hw_failure_emergency_poweroff_func - emergency poweroff work after a known delay 930 * @work: work_struct associated with the emergency poweroff function 931 * 932 * This function is called in very critical situations to force 933 * a kernel poweroff after a configurable timeout value. 934 */ 935static void hw_failure_emergency_poweroff_func(struct work_struct *work) 936{ 937 /* 938 * We have reached here after the emergency shutdown waiting period has 939 * expired. This means orderly_poweroff has not been able to shut off 940 * the system for some reason. 941 * 942 * Try to shut down the system immediately using kernel_power_off 943 * if populated 944 */ 945 pr_emerg("Hardware protection timed-out. Trying forced poweroff\n"); 946 kernel_power_off(); 947 948 /* 949 * Worst of the worst case trigger emergency restart 950 */ 951 pr_emerg("Hardware protection shutdown failed. Trying emergency restart\n"); 952 emergency_restart(); 953} 954 955static DECLARE_DELAYED_WORK(hw_failure_emergency_poweroff_work, 956 hw_failure_emergency_poweroff_func); 957 958/** 959 * hw_failure_emergency_poweroff - Trigger an emergency system poweroff 960 * 961 * This may be called from any critical situation to trigger a system shutdown 962 * after a given period of time. If time is negative this is not scheduled. 963 */ 964static void hw_failure_emergency_poweroff(int poweroff_delay_ms) 965{ 966 if (poweroff_delay_ms <= 0) 967 return; 968 schedule_delayed_work(&hw_failure_emergency_poweroff_work, 969 msecs_to_jiffies(poweroff_delay_ms)); 970} 971 972/** 973 * __hw_protection_shutdown - Trigger an emergency system shutdown or reboot 974 * 975 * @reason: Reason of emergency shutdown or reboot to be printed. 976 * @ms_until_forced: Time to wait for orderly shutdown or reboot before 977 * triggering it. Negative value disables the forced 978 * shutdown or reboot. 979 * @shutdown: If true, indicates that a shutdown will happen 980 * after the critical tempeature is reached. 981 * If false, indicates that a reboot will happen 982 * after the critical tempeature is reached. 983 * 984 * Initiate an emergency system shutdown or reboot in order to protect 985 * hardware from further damage. Usage examples include a thermal protection. 986 * NOTE: The request is ignored if protection shutdown or reboot is already 987 * pending even if the previous request has given a large timeout for forced 988 * shutdown/reboot. 989 */ 990void __hw_protection_shutdown(const char *reason, int ms_until_forced, bool shutdown) 991{ 992 static atomic_t allow_proceed = ATOMIC_INIT(1); 993 994 pr_emerg("HARDWARE PROTECTION shutdown (%s)\n", reason); 995 996 /* Shutdown should be initiated only once. */ 997 if (!atomic_dec_and_test(&allow_proceed)) 998 return; 999 1000 /* 1001 * Queue a backup emergency shutdown in the event of 1002 * orderly_poweroff failure 1003 */ 1004 hw_failure_emergency_poweroff(ms_until_forced); 1005 if (shutdown) 1006 orderly_poweroff(true); 1007 else 1008 orderly_reboot(); 1009} 1010EXPORT_SYMBOL_GPL(__hw_protection_shutdown); 1011 1012static int __init reboot_setup(char *str) 1013{ 1014 for (;;) { 1015 enum reboot_mode *mode; 1016 1017 /* 1018 * Having anything passed on the command line via 1019 * reboot= will cause us to disable DMI checking 1020 * below. 1021 */ 1022 reboot_default = 0; 1023 1024 if (!strncmp(str, "panic_", 6)) { 1025 mode = &panic_reboot_mode; 1026 str += 6; 1027 } else { 1028 mode = &reboot_mode; 1029 } 1030 1031 switch (*str) { 1032 case 'w': 1033 *mode = REBOOT_WARM; 1034 break; 1035 1036 case 'c': 1037 *mode = REBOOT_COLD; 1038 break; 1039 1040 case 'h': 1041 *mode = REBOOT_HARD; 1042 break; 1043 1044 case 's': 1045 /* 1046 * reboot_cpu is s[mp]#### with #### being the processor 1047 * to be used for rebooting. Skip 's' or 'smp' prefix. 1048 */ 1049 str += str[1] == 'm' && str[2] == 'p' ? 3 : 1; 1050 1051 if (isdigit(str[0])) { 1052 int cpu = simple_strtoul(str, NULL, 0); 1053 1054 if (cpu >= num_possible_cpus()) { 1055 pr_err("Ignoring the CPU number in reboot= option. " 1056 "CPU %d exceeds possible cpu number %d\n", 1057 cpu, num_possible_cpus()); 1058 break; 1059 } 1060 reboot_cpu = cpu; 1061 } else 1062 *mode = REBOOT_SOFT; 1063 break; 1064 1065 case 'g': 1066 *mode = REBOOT_GPIO; 1067 break; 1068 1069 case 'b': 1070 case 'a': 1071 case 'k': 1072 case 't': 1073 case 'e': 1074 case 'p': 1075 reboot_type = *str; 1076 break; 1077 1078 case 'f': 1079 reboot_force = 1; 1080 break; 1081 } 1082 1083 str = strchr(str, ','); 1084 if (str) 1085 str++; 1086 else 1087 break; 1088 } 1089 return 1; 1090} 1091__setup("reboot=", reboot_setup); 1092 1093#ifdef CONFIG_SYSFS 1094 1095#define REBOOT_COLD_STR "cold" 1096#define REBOOT_WARM_STR "warm" 1097#define REBOOT_HARD_STR "hard" 1098#define REBOOT_SOFT_STR "soft" 1099#define REBOOT_GPIO_STR "gpio" 1100#define REBOOT_UNDEFINED_STR "undefined" 1101 1102#define BOOT_TRIPLE_STR "triple" 1103#define BOOT_KBD_STR "kbd" 1104#define BOOT_BIOS_STR "bios" 1105#define BOOT_ACPI_STR "acpi" 1106#define BOOT_EFI_STR "efi" 1107#define BOOT_PCI_STR "pci" 1108 1109static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1110{ 1111 const char *val; 1112 1113 switch (reboot_mode) { 1114 case REBOOT_COLD: 1115 val = REBOOT_COLD_STR; 1116 break; 1117 case REBOOT_WARM: 1118 val = REBOOT_WARM_STR; 1119 break; 1120 case REBOOT_HARD: 1121 val = REBOOT_HARD_STR; 1122 break; 1123 case REBOOT_SOFT: 1124 val = REBOOT_SOFT_STR; 1125 break; 1126 case REBOOT_GPIO: 1127 val = REBOOT_GPIO_STR; 1128 break; 1129 default: 1130 val = REBOOT_UNDEFINED_STR; 1131 } 1132 1133 return sprintf(buf, "%s\n", val); 1134} 1135static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr, 1136 const char *buf, size_t count) 1137{ 1138 if (!capable(CAP_SYS_BOOT)) 1139 return -EPERM; 1140 1141 if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR))) 1142 reboot_mode = REBOOT_COLD; 1143 else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR))) 1144 reboot_mode = REBOOT_WARM; 1145 else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR))) 1146 reboot_mode = REBOOT_HARD; 1147 else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR))) 1148 reboot_mode = REBOOT_SOFT; 1149 else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR))) 1150 reboot_mode = REBOOT_GPIO; 1151 else 1152 return -EINVAL; 1153 1154 reboot_default = 0; 1155 1156 return count; 1157} 1158static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode); 1159 1160#ifdef CONFIG_X86 1161static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1162{ 1163 return sprintf(buf, "%d\n", reboot_force); 1164} 1165static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr, 1166 const char *buf, size_t count) 1167{ 1168 bool res; 1169 1170 if (!capable(CAP_SYS_BOOT)) 1171 return -EPERM; 1172 1173 if (kstrtobool(buf, &res)) 1174 return -EINVAL; 1175 1176 reboot_default = 0; 1177 reboot_force = res; 1178 1179 return count; 1180} 1181static struct kobj_attribute reboot_force_attr = __ATTR_RW(force); 1182 1183static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1184{ 1185 const char *val; 1186 1187 switch (reboot_type) { 1188 case BOOT_TRIPLE: 1189 val = BOOT_TRIPLE_STR; 1190 break; 1191 case BOOT_KBD: 1192 val = BOOT_KBD_STR; 1193 break; 1194 case BOOT_BIOS: 1195 val = BOOT_BIOS_STR; 1196 break; 1197 case BOOT_ACPI: 1198 val = BOOT_ACPI_STR; 1199 break; 1200 case BOOT_EFI: 1201 val = BOOT_EFI_STR; 1202 break; 1203 case BOOT_CF9_FORCE: 1204 val = BOOT_PCI_STR; 1205 break; 1206 default: 1207 val = REBOOT_UNDEFINED_STR; 1208 } 1209 1210 return sprintf(buf, "%s\n", val); 1211} 1212static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr, 1213 const char *buf, size_t count) 1214{ 1215 if (!capable(CAP_SYS_BOOT)) 1216 return -EPERM; 1217 1218 if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR))) 1219 reboot_type = BOOT_TRIPLE; 1220 else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR))) 1221 reboot_type = BOOT_KBD; 1222 else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR))) 1223 reboot_type = BOOT_BIOS; 1224 else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR))) 1225 reboot_type = BOOT_ACPI; 1226 else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR))) 1227 reboot_type = BOOT_EFI; 1228 else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR))) 1229 reboot_type = BOOT_CF9_FORCE; 1230 else 1231 return -EINVAL; 1232 1233 reboot_default = 0; 1234 1235 return count; 1236} 1237static struct kobj_attribute reboot_type_attr = __ATTR_RW(type); 1238#endif 1239 1240#ifdef CONFIG_SMP 1241static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) 1242{ 1243 return sprintf(buf, "%d\n", reboot_cpu); 1244} 1245static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr, 1246 const char *buf, size_t count) 1247{ 1248 unsigned int cpunum; 1249 int rc; 1250 1251 if (!capable(CAP_SYS_BOOT)) 1252 return -EPERM; 1253 1254 rc = kstrtouint(buf, 0, &cpunum); 1255 1256 if (rc) 1257 return rc; 1258 1259 if (cpunum >= num_possible_cpus()) 1260 return -ERANGE; 1261 1262 reboot_default = 0; 1263 reboot_cpu = cpunum; 1264 1265 return count; 1266} 1267static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu); 1268#endif 1269 1270static struct attribute *reboot_attrs[] = { 1271 &reboot_mode_attr.attr, 1272#ifdef CONFIG_X86 1273 &reboot_force_attr.attr, 1274 &reboot_type_attr.attr, 1275#endif 1276#ifdef CONFIG_SMP 1277 &reboot_cpu_attr.attr, 1278#endif 1279 NULL, 1280}; 1281 1282#ifdef CONFIG_SYSCTL 1283static struct ctl_table kern_reboot_table[] = { 1284 { 1285 .procname = "poweroff_cmd", 1286 .data = &poweroff_cmd, 1287 .maxlen = POWEROFF_CMD_PATH_LEN, 1288 .mode = 0644, 1289 .proc_handler = proc_dostring, 1290 }, 1291 { 1292 .procname = "ctrl-alt-del", 1293 .data = &C_A_D, 1294 .maxlen = sizeof(int), 1295 .mode = 0644, 1296 .proc_handler = proc_dointvec, 1297 }, 1298}; 1299 1300static void __init kernel_reboot_sysctls_init(void) 1301{ 1302 register_sysctl_init("kernel", kern_reboot_table); 1303} 1304#else 1305#define kernel_reboot_sysctls_init() do { } while (0) 1306#endif /* CONFIG_SYSCTL */ 1307 1308static const struct attribute_group reboot_attr_group = { 1309 .attrs = reboot_attrs, 1310}; 1311 1312static int __init reboot_ksysfs_init(void) 1313{ 1314 struct kobject *reboot_kobj; 1315 int ret; 1316 1317 reboot_kobj = kobject_create_and_add("reboot", kernel_kobj); 1318 if (!reboot_kobj) 1319 return -ENOMEM; 1320 1321 ret = sysfs_create_group(reboot_kobj, &reboot_attr_group); 1322 if (ret) { 1323 kobject_put(reboot_kobj); 1324 return ret; 1325 } 1326 1327 kernel_reboot_sysctls_init(); 1328 1329 return 0; 1330} 1331late_initcall(reboot_ksysfs_init); 1332 1333#endif 1334