kernel/reboot.c

   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/ctype.h>
  11 #include <linux/export.h>
  12 #include <linux/kexec.h>
  13 #include <linux/kmod.h>
  14 #include <linux/kmsg_dump.h>
  15 #include <linux/reboot.h>
  16 #include <linux/suspend.h>
  17 #include <linux/syscalls.h>
  18 #include <linux/syscore_ops.h>
  19 #include <linux/uaccess.h>
  20
  21 /*
  22  * this indicates whether you can reboot with ctrl-alt-del: the default is yes
  23  */
  24
  25 int C_A_D = 1;
  26 struct pid *cad_pid;
  27 EXPORT_SYMBOL(cad_pid);
  28
  29 #if defined(CONFIG_ARM)
  30 #define DEFAULT_REBOOT_MODE             = REBOOT_HARD
  31 #else
  32 #define DEFAULT_REBOOT_MODE
  33 #endif
  34 enum reboot_mode reboot_mode DEFAULT_REBOOT_MODE;
  35 enum reboot_mode panic_reboot_mode = REBOOT_UNDEFINED;
  36
  37 /*
  38  * This variable is used privately to keep track of whether or not
  39  * reboot_type is still set to its default value (i.e., reboot= hasn't
  40  * been set on the command line).  This is needed so that we can
  41  * suppress DMI scanning for reboot quirks.  Without it, it's
  42  * impossible to override a faulty reboot quirk without recompiling.
  43  */
  44 int reboot_default = 1;
  45 int reboot_cpu;
  46 enum reboot_type reboot_type = BOOT_ACPI;
  47 int reboot_force;
  48
  49 /*
  50  * If set, this is used for preparing the system to power off.
  51  */
  52
  53 void (*pm_power_off_prepare)(void);
  54 EXPORT_SYMBOL_GPL(pm_power_off_prepare);
  55
  56 /**
  57  *      emergency_restart - reboot the system
  58  *
  59  *      Without shutting down any hardware or taking any locks
  60  *      reboot the system.  This is called when we know we are in
  61  *      trouble so this is our best effort to reboot.  This is
  62  *      safe to call in interrupt context.
  63  */
  64 void emergency_restart(void)
  65 {
  66         kmsg_dump(KMSG_DUMP_EMERG);
  67         machine_emergency_restart();
  68 }
  69 EXPORT_SYMBOL_GPL(emergency_restart);
  70
  71 void kernel_restart_prepare(char *cmd)
  72 {
  73         blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
  74         system_state = SYSTEM_RESTART;
  75         usermodehelper_disable();
  76         device_shutdown();
  77 }
  78
  79 /**
  80  *      register_reboot_notifier - Register function to be called at reboot time
  81  *      @nb: Info about notifier function to be called
  82  *
  83  *      Registers a function with the list of functions
  84  *      to be called at reboot time.
  85  *
  86  *      Currently always returns zero, as blocking_notifier_chain_register()
  87  *      always returns zero.
  88  */
  89 int register_reboot_notifier(struct notifier_block *nb)
  90 {
  91         return blocking_notifier_chain_register(&reboot_notifier_list, nb);
  92 }
  93 EXPORT_SYMBOL(register_reboot_notifier);
  94
  95 /**
  96  *      unregister_reboot_notifier - Unregister previously registered reboot notifier
  97  *      @nb: Hook to be unregistered
  98  *
  99  *      Unregisters a previously registered reboot
 100  *      notifier function.
 101  *
 102  *      Returns zero on success, or %-ENOENT on failure.
 103  */
 104 int unregister_reboot_notifier(struct notifier_block *nb)
 105 {
 106         return blocking_notifier_chain_unregister(&reboot_notifier_list, nb);
 107 }
 108 EXPORT_SYMBOL(unregister_reboot_notifier);
 109
 110 static void devm_unregister_reboot_notifier(struct device *dev, void *res)
 111 {
 112         WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
 113 }
 114
 115 int devm_register_reboot_notifier(struct device *dev, struct notifier_block *nb)
 116 {
 117         struct notifier_block **rcnb;
 118         int ret;
 119
 120         rcnb = devres_alloc(devm_unregister_reboot_notifier,
 121                             sizeof(*rcnb), GFP_KERNEL);
 122         if (!rcnb)
 123                 return -ENOMEM;
 124
 125         ret = register_reboot_notifier(nb);
 126         if (!ret) {
 127                 *rcnb = nb;
 128                 devres_add(dev, rcnb);
 129         } else {
 130                 devres_free(rcnb);
 131         }
 132
 133         return ret;
 134 }
 135 EXPORT_SYMBOL(devm_register_reboot_notifier);
 136
 137 /*
 138  *      Notifier list for kernel code which wants to be called
 139  *      to restart the system.
 140  */
 141 static ATOMIC_NOTIFIER_HEAD(restart_handler_list);
 142
 143 /**
 144  *      register_restart_handler - Register function to be called to reset
 145  *                                 the system
 146  *      @nb: Info about handler function to be called
 147  *      @nb->priority:  Handler priority. Handlers should follow the
 148  *                      following guidelines for setting priorities.
 149  *                      0:      Restart handler of last resort,
 150  *                              with limited restart capabilities
 151  *                      128:    Default restart handler; use if no other
 152  *                              restart handler is expected to be available,
 153  *                              and/or if restart functionality is
 154  *                              sufficient to restart the entire system
 155  *                      255:    Highest priority restart handler, will
 156  *                              preempt all other restart handlers
 157  *
 158  *      Registers a function with code to be called to restart the
 159  *      system.
 160  *
 161  *      Registered functions will be called from machine_restart as last
 162  *      step of the restart sequence (if the architecture specific
 163  *      machine_restart function calls do_kernel_restart - see below
 164  *      for details).
 165  *      Registered functions are expected to restart the system immediately.
 166  *      If more than one function is registered, the restart handler priority
 167  *      selects which function will be called first.
 168  *
 169  *      Restart handlers are expected to be registered from non-architecture
 170  *      code, typically from drivers. A typical use case would be a system
 171  *      where restart functionality is provided through a watchdog. Multiple
 172  *      restart handlers may exist; for example, one restart handler might
 173  *      restart the entire system, while another only restarts the CPU.
 174  *      In such cases, the restart handler which only restarts part of the
 175  *      hardware is expected to register with low priority to ensure that
 176  *      it only runs if no other means to restart the system is available.
 177  *
 178  *      Currently always returns zero, as atomic_notifier_chain_register()
 179  *      always returns zero.
 180  */
 181 int register_restart_handler(struct notifier_block *nb)
 182 {
 183         return atomic_notifier_chain_register(&restart_handler_list, nb);
 184 }
 185 EXPORT_SYMBOL(register_restart_handler);
 186
 187 /**
 188  *      unregister_restart_handler - Unregister previously registered
 189  *                                   restart handler
 190  *      @nb: Hook to be unregistered
 191  *
 192  *      Unregisters a previously registered restart handler function.
 193  *
 194  *      Returns zero on success, or %-ENOENT on failure.
 195  */
 196 int unregister_restart_handler(struct notifier_block *nb)
 197 {
 198         return atomic_notifier_chain_unregister(&restart_handler_list, nb);
 199 }
 200 EXPORT_SYMBOL(unregister_restart_handler);
 201
 202 /**
 203  *      do_kernel_restart - Execute kernel restart handler call chain
 204  *
 205  *      Calls functions registered with register_restart_handler.
 206  *
 207  *      Expected to be called from machine_restart as last step of the restart
 208  *      sequence.
 209  *
 210  *      Restarts the system immediately if a restart handler function has been
 211  *      registered. Otherwise does nothing.
 212  */
 213 void do_kernel_restart(char *cmd)
 214 {
 215         atomic_notifier_call_chain(&restart_handler_list, reboot_mode, cmd);
 216 }
 217
 218 void migrate_to_reboot_cpu(void)
 219 {
 220         /* The boot cpu is always logical cpu 0 */
 221         int cpu = reboot_cpu;
 222
 223         cpu_hotplug_disable();
 224
 225         /* Make certain the cpu I'm about to reboot on is online */
 226         if (!cpu_online(cpu))
 227                 cpu = cpumask_first(cpu_online_mask);
 228
 229         /* Prevent races with other tasks migrating this task */
 230         current->flags |= PF_NO_SETAFFINITY;
 231
 232         /* Make certain I only run on the appropriate processor */
 233         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 234 }
 235
 236 /**
 237  *      kernel_restart - reboot the system
 238  *      @cmd: pointer to buffer containing command to execute for restart
 239  *              or %NULL
 240  *
 241  *      Shutdown everything and perform a clean reboot.
 242  *      This is not safe to call in interrupt context.
 243  */
 244 void kernel_restart(char *cmd)
 245 {
 246         kernel_restart_prepare(cmd);
 247         if (pm_power_off_prepare)
 248                 pm_power_off_prepare();
 249         migrate_to_reboot_cpu();
 250         syscore_shutdown();
 251         if (!cmd)
 252                 pr_emerg("Restarting system\n");
 253         else
 254                 pr_emerg("Restarting system with command '%s'\n", cmd);
 255         kmsg_dump(KMSG_DUMP_SHUTDOWN);
 256         machine_restart(cmd);
 257 }
 258 EXPORT_SYMBOL_GPL(kernel_restart);
 259
 260 static void kernel_shutdown_prepare(enum system_states state)
 261 {
 262         blocking_notifier_call_chain(&reboot_notifier_list,
 263                 (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL);
 264         system_state = state;
 265         usermodehelper_disable();
 266         device_shutdown();
 267 }
 268 /**
 269  *      kernel_halt - halt the system
 270  *
 271  *      Shutdown everything and perform a clean system halt.
 272  */
 273 void kernel_halt(void)
 274 {
 275         kernel_shutdown_prepare(SYSTEM_HALT);
 276         migrate_to_reboot_cpu();
 277         syscore_shutdown();
 278         pr_emerg("System halted\n");
 279         kmsg_dump(KMSG_DUMP_SHUTDOWN);
 280         machine_halt();
 281 }
 282 EXPORT_SYMBOL_GPL(kernel_halt);
 283
 284 /**
 285  *      kernel_power_off - power_off the system
 286  *
 287  *      Shutdown everything and perform a clean system power_off.
 288  */
 289 void kernel_power_off(void)
 290 {
 291         kernel_shutdown_prepare(SYSTEM_POWER_OFF);
 292         if (pm_power_off_prepare)
 293                 pm_power_off_prepare();
 294         migrate_to_reboot_cpu();
 295         syscore_shutdown();
 296         pr_emerg("Power down\n");
 297         kmsg_dump(KMSG_DUMP_SHUTDOWN);
 298         machine_power_off();
 299 }
 300 EXPORT_SYMBOL_GPL(kernel_power_off);
 301
 302 DEFINE_MUTEX(system_transition_mutex);
 303
 304 /*
 305  * Reboot system call: for obvious reasons only root may call it,
 306  * and even root needs to set up some magic numbers in the registers
 307  * so that some mistake won't make this reboot the whole machine.
 308  * You can also set the meaning of the ctrl-alt-del-key here.
 309  *
 310  * reboot doesn't sync: do that yourself before calling this.
 311  */
 312 SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 313                 void __user *, arg)
 314 {
 315         struct pid_namespace *pid_ns = task_active_pid_ns(current);
 316         char buffer[256];
 317         int ret = 0;
 318
 319         /* We only trust the superuser with rebooting the system. */
 320         if (!ns_capable(pid_ns->user_ns, CAP_SYS_BOOT))
 321                 return -EPERM;
 322
 323         /* For safety, we require "magic" arguments. */
 324         if (magic1 != LINUX_REBOOT_MAGIC1 ||
 325                         (magic2 != LINUX_REBOOT_MAGIC2 &&
 326                         magic2 != LINUX_REBOOT_MAGIC2A &&
 327                         magic2 != LINUX_REBOOT_MAGIC2B &&
 328                         magic2 != LINUX_REBOOT_MAGIC2C))
 329                 return -EINVAL;
 330
 331         /*
 332          * If pid namespaces are enabled and the current task is in a child
 333          * pid_namespace, the command is handled by reboot_pid_ns() which will
 334          * call do_exit().
 335          */
 336         ret = reboot_pid_ns(pid_ns, cmd);
 337         if (ret)
 338                 return ret;
 339
 340         /* Instead of trying to make the power_off code look like
 341          * halt when pm_power_off is not set do it the easy way.
 342          */
 343         if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
 344                 cmd = LINUX_REBOOT_CMD_HALT;
 345
 346         mutex_lock(&system_transition_mutex);
 347         switch (cmd) {
 348         case LINUX_REBOOT_CMD_RESTART:
 349                 kernel_restart(NULL);
 350                 break;
 351
 352         case LINUX_REBOOT_CMD_CAD_ON:
 353                 C_A_D = 1;
 354                 break;
 355
 356         case LINUX_REBOOT_CMD_CAD_OFF:
 357                 C_A_D = 0;
 358                 break;
 359
 360         case LINUX_REBOOT_CMD_HALT:
 361                 kernel_halt();
 362                 do_exit(0);
 363                 panic("cannot halt");
 364
 365         case LINUX_REBOOT_CMD_POWER_OFF:
 366                 kernel_power_off();
 367                 do_exit(0);
 368                 break;
 369
 370         case LINUX_REBOOT_CMD_RESTART2:
 371                 ret = strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1);
 372                 if (ret < 0) {
 373                         ret = -EFAULT;
 374                         break;
 375                 }
 376                 buffer[sizeof(buffer) - 1] = '\0';
 377
 378                 kernel_restart(buffer);
 379                 break;
 380
 381 #ifdef CONFIG_KEXEC_CORE
 382         case LINUX_REBOOT_CMD_KEXEC:
 383                 ret = kernel_kexec();
 384                 break;
 385 #endif
 386
 387 #ifdef CONFIG_HIBERNATION
 388         case LINUX_REBOOT_CMD_SW_SUSPEND:
 389                 ret = hibernate();
 390                 break;
 391 #endif
 392
 393         default:
 394                 ret = -EINVAL;
 395                 break;
 396         }
 397         mutex_unlock(&system_transition_mutex);
 398         return ret;
 399 }
 400
 401 static void deferred_cad(struct work_struct *dummy)
 402 {
 403         kernel_restart(NULL);
 404 }
 405
 406 /*
 407  * This function gets called by ctrl-alt-del - ie the keyboard interrupt.
 408  * As it's called within an interrupt, it may NOT sync: the only choice
 409  * is whether to reboot at once, or just ignore the ctrl-alt-del.
 410  */
 411 void ctrl_alt_del(void)
 412 {
 413         static DECLARE_WORK(cad_work, deferred_cad);
 414
 415         if (C_A_D)
 416                 schedule_work(&cad_work);
 417         else
 418                 kill_cad_pid(SIGINT, 1);
 419 }
 420
 421 char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
 422 static const char reboot_cmd[] = "/sbin/reboot";
 423
 424 static int run_cmd(const char *cmd)
 425 {
 426         char **argv;
 427         static char *envp[] = {
 428                 "HOME=/",
 429                 "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
 430                 NULL
 431         };
 432         int ret;
 433         argv = argv_split(GFP_KERNEL, cmd, NULL);
 434         if (argv) {
 435                 ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
 436                 argv_free(argv);
 437         } else {
 438                 ret = -ENOMEM;
 439         }
 440
 441         return ret;
 442 }
 443
 444 static int __orderly_reboot(void)
 445 {
 446         int ret;
 447
 448         ret = run_cmd(reboot_cmd);
 449
 450         if (ret) {
 451                 pr_warn("Failed to start orderly reboot: forcing the issue\n");
 452                 emergency_sync();
 453                 kernel_restart(NULL);
 454         }
 455
 456         return ret;
 457 }
 458
 459 static int __orderly_poweroff(bool force)
 460 {
 461         int ret;
 462
 463         ret = run_cmd(poweroff_cmd);
 464
 465         if (ret && force) {
 466                 pr_warn("Failed to start orderly shutdown: forcing the issue\n");
 467
 468                 /*
 469                  * I guess this should try to kick off some daemon to sync and
 470                  * poweroff asap.  Or not even bother syncing if we're doing an
 471                  * emergency shutdown?
 472                  */
 473                 emergency_sync();
 474                 kernel_power_off();
 475         }
 476
 477         return ret;
 478 }
 479
 480 static bool poweroff_force;
 481
 482 static void poweroff_work_func(struct work_struct *work)
 483 {
 484         __orderly_poweroff(poweroff_force);
 485 }
 486
 487 static DECLARE_WORK(poweroff_work, poweroff_work_func);
 488
 489 /**
 490  * orderly_poweroff - Trigger an orderly system poweroff
 491  * @force: force poweroff if command execution fails
 492  *
 493  * This may be called from any context to trigger a system shutdown.
 494  * If the orderly shutdown fails, it will force an immediate shutdown.
 495  */
 496 void orderly_poweroff(bool force)
 497 {
 498         if (force) /* do not override the pending "true" */
 499                 poweroff_force = true;
 500         schedule_work(&poweroff_work);
 501 }
 502 EXPORT_SYMBOL_GPL(orderly_poweroff);
 503
 504 static void reboot_work_func(struct work_struct *work)
 505 {
 506         __orderly_reboot();
 507 }
 508
 509 static DECLARE_WORK(reboot_work, reboot_work_func);
 510
 511 /**
 512  * orderly_reboot - Trigger an orderly system reboot
 513  *
 514  * This may be called from any context to trigger a system reboot.
 515  * If the orderly reboot fails, it will force an immediate reboot.
 516  */
 517 void orderly_reboot(void)
 518 {
 519         schedule_work(&reboot_work);
 520 }
 521 EXPORT_SYMBOL_GPL(orderly_reboot);
 522
 523 static int __init reboot_setup(char *str)
 524 {
 525         for (;;) {
 526                 enum reboot_mode *mode;
 527
 528                 /*
 529                  * Having anything passed on the command line via
 530                  * reboot= will cause us to disable DMI checking
 531                  * below.
 532                  */
 533                 reboot_default = 0;
 534
 535                 if (!strncmp(str, "panic_", 6)) {
 536                         mode = &panic_reboot_mode;
 537                         str += 6;
 538                 } else {
 539                         mode = &reboot_mode;
 540                 }
 541
 542                 switch (*str) {
 543                 case 'w':
 544                         *mode = REBOOT_WARM;
 545                         break;
 546
 547                 case 'c':
 548                         *mode = REBOOT_COLD;
 549                         break;
 550
 551                 case 'h':
 552                         *mode = REBOOT_HARD;
 553                         break;
 554
 555                 case 's':
 556                         /*
 557                          * reboot_cpu is s[mp]#### with #### being the processor
 558                          * to be used for rebooting. Skip 's' or 'smp' prefix.
 559                          */
 560                         str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
 561
 562                         if (isdigit(str[0])) {
 563                                 int cpu = simple_strtoul(str, NULL, 0);
 564
 565                                 if (cpu >= num_possible_cpus()) {
 566                                         pr_err("Ignoring the CPU number in reboot= option. "
 567                                         "CPU %d exceeds possible cpu number %d\n",
 568                                         cpu, num_possible_cpus());
 569                                         break;
 570                                 }
 571                                 reboot_cpu = cpu;
 572                         } else
 573                                 *mode = REBOOT_SOFT;
 574                         break;
 575
 576                 case 'g':
 577                         *mode = REBOOT_GPIO;
 578                         break;
 579
 580                 case 'b':
 581                 case 'a':
 582                 case 'k':
 583                 case 't':
 584                 case 'e':
 585                 case 'p':
 586                         reboot_type = *str;
 587                         break;
 588
 589                 case 'f':
 590                         reboot_force = 1;
 591                         break;
 592                 }
 593
 594                 str = strchr(str, ',');
 595                 if (str)
 596                         str++;
 597                 else
 598                         break;
 599         }
 600         return 1;
 601 }
 602 __setup("reboot=", reboot_setup);
 603
 604 #ifdef CONFIG_SYSFS
 605
 606 #define REBOOT_COLD_STR         "cold"
 607 #define REBOOT_WARM_STR         "warm"
 608 #define REBOOT_HARD_STR         "hard"
 609 #define REBOOT_SOFT_STR         "soft"
 610 #define REBOOT_GPIO_STR         "gpio"
 611 #define REBOOT_UNDEFINED_STR    "undefined"
 612
 613 #define BOOT_TRIPLE_STR         "triple"
 614 #define BOOT_KBD_STR            "kbd"
 615 #define BOOT_BIOS_STR           "bios"
 616 #define BOOT_ACPI_STR           "acpi"
 617 #define BOOT_EFI_STR            "efi"
 618 #define BOOT_PCI_STR            "pci"
 619
 620 static ssize_t mode_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 621 {
 622         const char *val;
 623
 624         switch (reboot_mode) {
 625         case REBOOT_COLD:
 626                 val = REBOOT_COLD_STR;
 627                 break;
 628         case REBOOT_WARM:
 629                 val = REBOOT_WARM_STR;
 630                 break;
 631         case REBOOT_HARD:
 632                 val = REBOOT_HARD_STR;
 633                 break;
 634         case REBOOT_SOFT:
 635                 val = REBOOT_SOFT_STR;
 636                 break;
 637         case REBOOT_GPIO:
 638                 val = REBOOT_GPIO_STR;
 639                 break;
 640         default:
 641                 val = REBOOT_UNDEFINED_STR;
 642         }
 643
 644         return sprintf(buf, "%s\n", val);
 645 }
 646 static ssize_t mode_store(struct kobject *kobj, struct kobj_attribute *attr,
 647                           const char *buf, size_t count)
 648 {
 649         if (!capable(CAP_SYS_BOOT))
 650                 return -EPERM;
 651
 652         if (!strncmp(buf, REBOOT_COLD_STR, strlen(REBOOT_COLD_STR)))
 653                 reboot_mode = REBOOT_COLD;
 654         else if (!strncmp(buf, REBOOT_WARM_STR, strlen(REBOOT_WARM_STR)))
 655                 reboot_mode = REBOOT_WARM;
 656         else if (!strncmp(buf, REBOOT_HARD_STR, strlen(REBOOT_HARD_STR)))
 657                 reboot_mode = REBOOT_HARD;
 658         else if (!strncmp(buf, REBOOT_SOFT_STR, strlen(REBOOT_SOFT_STR)))
 659                 reboot_mode = REBOOT_SOFT;
 660         else if (!strncmp(buf, REBOOT_GPIO_STR, strlen(REBOOT_GPIO_STR)))
 661                 reboot_mode = REBOOT_GPIO;
 662         else
 663                 return -EINVAL;
 664
 665         reboot_default = 0;
 666
 667         return count;
 668 }
 669 static struct kobj_attribute reboot_mode_attr = __ATTR_RW(mode);
 670
 671 #ifdef CONFIG_X86
 672 static ssize_t force_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 673 {
 674         return sprintf(buf, "%d\n", reboot_force);
 675 }
 676 static ssize_t force_store(struct kobject *kobj, struct kobj_attribute *attr,
 677                           const char *buf, size_t count)
 678 {
 679         bool res;
 680
 681         if (!capable(CAP_SYS_BOOT))
 682                 return -EPERM;
 683
 684         if (kstrtobool(buf, &res))
 685                 return -EINVAL;
 686
 687         reboot_default = 0;
 688         reboot_force = res;
 689
 690         return count;
 691 }
 692 static struct kobj_attribute reboot_force_attr = __ATTR_RW(force);
 693
 694 static ssize_t type_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 695 {
 696         const char *val;
 697
 698         switch (reboot_type) {
 699         case BOOT_TRIPLE:
 700                 val = BOOT_TRIPLE_STR;
 701                 break;
 702         case BOOT_KBD:
 703                 val = BOOT_KBD_STR;
 704                 break;
 705         case BOOT_BIOS:
 706                 val = BOOT_BIOS_STR;
 707                 break;
 708         case BOOT_ACPI:
 709                 val = BOOT_ACPI_STR;
 710                 break;
 711         case BOOT_EFI:
 712                 val = BOOT_EFI_STR;
 713                 break;
 714         case BOOT_CF9_FORCE:
 715                 val = BOOT_PCI_STR;
 716                 break;
 717         default:
 718                 val = REBOOT_UNDEFINED_STR;
 719         }
 720
 721         return sprintf(buf, "%s\n", val);
 722 }
 723 static ssize_t type_store(struct kobject *kobj, struct kobj_attribute *attr,
 724                           const char *buf, size_t count)
 725 {
 726         if (!capable(CAP_SYS_BOOT))
 727                 return -EPERM;
 728
 729         if (!strncmp(buf, BOOT_TRIPLE_STR, strlen(BOOT_TRIPLE_STR)))
 730                 reboot_type = BOOT_TRIPLE;
 731         else if (!strncmp(buf, BOOT_KBD_STR, strlen(BOOT_KBD_STR)))
 732                 reboot_type = BOOT_KBD;
 733         else if (!strncmp(buf, BOOT_BIOS_STR, strlen(BOOT_BIOS_STR)))
 734                 reboot_type = BOOT_BIOS;
 735         else if (!strncmp(buf, BOOT_ACPI_STR, strlen(BOOT_ACPI_STR)))
 736                 reboot_type = BOOT_ACPI;
 737         else if (!strncmp(buf, BOOT_EFI_STR, strlen(BOOT_EFI_STR)))
 738                 reboot_type = BOOT_EFI;
 739         else if (!strncmp(buf, BOOT_PCI_STR, strlen(BOOT_PCI_STR)))
 740                 reboot_type = BOOT_CF9_FORCE;
 741         else
 742                 return -EINVAL;
 743
 744         reboot_default = 0;
 745
 746         return count;
 747 }
 748 static struct kobj_attribute reboot_type_attr = __ATTR_RW(type);
 749 #endif
 750
 751 #ifdef CONFIG_SMP
 752 static ssize_t cpu_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 753 {
 754         return sprintf(buf, "%d\n", reboot_cpu);
 755 }
 756 static ssize_t cpu_store(struct kobject *kobj, struct kobj_attribute *attr,
 757                           const char *buf, size_t count)
 758 {
 759         unsigned int cpunum;
 760         int rc;
 761
 762         if (!capable(CAP_SYS_BOOT))
 763                 return -EPERM;
 764
 765         rc = kstrtouint(buf, 0, &cpunum);
 766
 767         if (rc)
 768                 return rc;
 769
 770         if (cpunum >= num_possible_cpus())
 771                 return -ERANGE;
 772
 773         reboot_default = 0;
 774         reboot_cpu = cpunum;
 775
 776         return count;
 777 }
 778 static struct kobj_attribute reboot_cpu_attr = __ATTR_RW(cpu);
 779 #endif
 780
 781 static struct attribute *reboot_attrs[] = {
 782         &reboot_mode_attr.attr,
 783 #ifdef CONFIG_X86
 784         &reboot_force_attr.attr,
 785         &reboot_type_attr.attr,
 786 #endif
 787 #ifdef CONFIG_SMP
 788         &reboot_cpu_attr.attr,
 789 #endif
 790         NULL,
 791 };
 792
 793 static const struct attribute_group reboot_attr_group = {
 794         .attrs = reboot_attrs,
 795 };
 796
 797 static int __init reboot_ksysfs_init(void)
 798 {
 799         struct kobject *reboot_kobj;
 800         int ret;
 801
 802         reboot_kobj = kobject_create_and_add("reboot", kernel_kobj);
 803         if (!reboot_kobj)
 804                 return -ENOMEM;
 805
 806         ret = sysfs_create_group(reboot_kobj, &reboot_attr_group);
 807         if (ret) {
 808                 kobject_put(reboot_kobj);
 809                 return ret;
 810         }
 811
 812         return 0;
 813 }
 814 late_initcall(reboot_ksysfs_init);
 815
 816 #endif