arch/x86/kernel/reboot.c

   1 #include <linux/module.h>
   2 #include <linux/reboot.h>
   3 #include <linux/init.h>
   4 #include <linux/pm.h>
   5 #include <linux/efi.h>
   6 #include <acpi/reboot.h>
   7 #include <asm/io.h>
   8 #include <asm/apic.h>
   9 #include <asm/desc.h>
  10 #include <asm/hpet.h>
  11 #include <asm/pgtable.h>
  12 #include <asm/proto.h>
  13 #include <asm/reboot_fixups.h>
  14 #include <asm/reboot.h>
  15 #include <asm/pci_x86.h>
  16 #include <asm/virtext.h>
  17 #include <asm/cpu.h>
  18
  19 #ifdef CONFIG_X86_32
  20 # include <linux/dmi.h>
  21 # include <linux/ctype.h>
  22 # include <linux/mc146818rtc.h>
  23 #else
  24 # include <asm/iommu.h>
  25 #endif
  26
  27 /*
  28  * Power off function, if any
  29  */
  30 void (*pm_power_off)(void);
  31 EXPORT_SYMBOL(pm_power_off);
  32
  33 static const struct desc_ptr no_idt = {};
  34 static int reboot_mode;
  35 enum reboot_type reboot_type = BOOT_KBD;
  36 int reboot_force;
  37
  38 #if defined(CONFIG_X86_32) && defined(CONFIG_SMP)
  39 static int reboot_cpu = -1;
  40 #endif
  41
  42 /* This is set if we need to go through the 'emergency' path.
  43  * When machine_emergency_restart() is called, we may be on
  44  * an inconsistent state and won't be able to do a clean cleanup
  45  */
  46 static int reboot_emergency;
  47
  48 /* This is set by the PCI code if either type 1 or type 2 PCI is detected */
  49 bool port_cf9_safe = false;
  50
  51 /* reboot=b[ios] | s[mp] | t[riple] | k[bd] | e[fi] [, [w]arm | [c]old] | p[ci]
  52    warm   Don't set the cold reboot flag
  53    cold   Set the cold reboot flag
  54    bios   Reboot by jumping through the BIOS (only for X86_32)
  55    smp    Reboot by executing reset on BSP or other CPU (only for X86_32)
  56    triple Force a triple fault (init)
  57    kbd    Use the keyboard controller. cold reset (default)
  58    acpi   Use the RESET_REG in the FADT
  59    efi    Use efi reset_system runtime service
  60    pci    Use the so-called "PCI reset register", CF9
  61    force  Avoid anything that could hang.
  62  */
  63 static int __init reboot_setup(char *str)
  64 {
  65         for (;;) {
  66                 switch (*str) {
  67                 case 'w':
  68                         reboot_mode = 0x1234;
  69                         break;
  70
  71                 case 'c':
  72                         reboot_mode = 0;
  73                         break;
  74
  75 #ifdef CONFIG_X86_32
  76 #ifdef CONFIG_SMP
  77                 case 's':
  78                         if (isdigit(*(str+1))) {
  79                                 reboot_cpu = (int) (*(str+1) - '0');
  80                                 if (isdigit(*(str+2)))
  81                                         reboot_cpu = reboot_cpu*10 + (int)(*(str+2) - '0');
  82                         }
  83                                 /* we will leave sorting out the final value
  84                                    when we are ready to reboot, since we might not
  85                                    have set up boot_cpu_id or smp_num_cpu */
  86                         break;
  87 #endif /* CONFIG_SMP */
  88
  89                 case 'b':
  90 #endif
  91                 case 'a':
  92                 case 'k':
  93                 case 't':
  94                 case 'e':
  95                 case 'p':
  96                         reboot_type = *str;
  97                         break;
  98
  99                 case 'f':
 100                         reboot_force = 1;
 101                         break;
 102                 }
 103
 104                 str = strchr(str, ',');
 105                 if (str)
 106                         str++;
 107                 else
 108                         break;
 109         }
 110         return 1;
 111 }
 112
 113 __setup("reboot=", reboot_setup);
 114
 115
 116 #ifdef CONFIG_X86_32
 117 /*
 118  * Reboot options and system auto-detection code provided by
 119  * Dell Inc. so their systems "just work". :-)
 120  */
 121
 122 /*
 123  * Some machines require the "reboot=b"  commandline option,
 124  * this quirk makes that automatic.
 125  */
 126 static int __init set_bios_reboot(const struct dmi_system_id *d)
 127 {
 128         if (reboot_type != BOOT_BIOS) {
 129                 reboot_type = BOOT_BIOS;
 130                 printk(KERN_INFO "%s series board detected. Selecting BIOS-method for reboots.\n", d->ident);
 131         }
 132         return 0;
 133 }
 134
 135 static struct dmi_system_id __initdata reboot_dmi_table[] = {
 136         {       /* Handle problems with rebooting on Dell E520's */
 137                 .callback = set_bios_reboot,
 138                 .ident = "Dell E520",
 139                 .matches = {
 140                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 141                         DMI_MATCH(DMI_PRODUCT_NAME, "Dell DM061"),
 142                 },
 143         },
 144         {       /* Handle problems with rebooting on Dell 1300's */
 145                 .callback = set_bios_reboot,
 146                 .ident = "Dell PowerEdge 1300",
 147                 .matches = {
 148                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
 149                         DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 1300/"),
 150                 },
 151         },
 152         {       /* Handle problems with rebooting on Dell 300's */
 153                 .callback = set_bios_reboot,
 154                 .ident = "Dell PowerEdge 300",
 155                 .matches = {
 156                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
 157                         DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 300/"),
 158                 },
 159         },
 160         {       /* Handle problems with rebooting on Dell Optiplex 745's SFF*/
 161                 .callback = set_bios_reboot,
 162                 .ident = "Dell OptiPlex 745",
 163                 .matches = {
 164                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 165                         DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
 166                 },
 167         },
 168         {       /* Handle problems with rebooting on Dell Optiplex 745's DFF*/
 169                 .callback = set_bios_reboot,
 170                 .ident = "Dell OptiPlex 745",
 171                 .matches = {
 172                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 173                         DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
 174                         DMI_MATCH(DMI_BOARD_NAME, "0MM599"),
 175                 },
 176         },
 177         {       /* Handle problems with rebooting on Dell Optiplex 745 with 0KW626 */
 178                 .callback = set_bios_reboot,
 179                 .ident = "Dell OptiPlex 745",
 180                 .matches = {
 181                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 182                         DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
 183                         DMI_MATCH(DMI_BOARD_NAME, "0KW626"),
 184                 },
 185         },
 186         {   /* Handle problems with rebooting on Dell Optiplex 330 with 0KP561 */
 187                 .callback = set_bios_reboot,
 188                 .ident = "Dell OptiPlex 330",
 189                 .matches = {
 190                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 191                         DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 330"),
 192                         DMI_MATCH(DMI_BOARD_NAME, "0KP561"),
 193                 },
 194         },
 195         {       /* Handle problems with rebooting on Dell 2400's */
 196                 .callback = set_bios_reboot,
 197                 .ident = "Dell PowerEdge 2400",
 198                 .matches = {
 199                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
 200                         DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 2400"),
 201                 },
 202         },
 203         {       /* Handle problems with rebooting on Dell T5400's */
 204                 .callback = set_bios_reboot,
 205                 .ident = "Dell Precision T5400",
 206                 .matches = {
 207                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 208                         DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T5400"),
 209                 },
 210         },
 211         {       /* Handle problems with rebooting on HP laptops */
 212                 .callback = set_bios_reboot,
 213                 .ident = "HP Compaq Laptop",
 214                 .matches = {
 215                         DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 216                         DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq"),
 217                 },
 218         },
 219         {       /* Handle problems with rebooting on Dell XPS710 */
 220                 .callback = set_bios_reboot,
 221                 .ident = "Dell XPS710",
 222                 .matches = {
 223                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 224                         DMI_MATCH(DMI_PRODUCT_NAME, "Dell XPS710"),
 225                 },
 226         },
 227         {       /* Handle problems with rebooting on Dell DXP061 */
 228                 .callback = set_bios_reboot,
 229                 .ident = "Dell DXP061",
 230                 .matches = {
 231                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 232                         DMI_MATCH(DMI_PRODUCT_NAME, "Dell DXP061"),
 233                 },
 234         },
 235         {       /* Handle problems with rebooting on Sony VGN-Z540N */
 236                 .callback = set_bios_reboot,
 237                 .ident = "Sony VGN-Z540N",
 238                 .matches = {
 239                         DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
 240                         DMI_MATCH(DMI_PRODUCT_NAME, "VGN-Z540N"),
 241                 },
 242         },
 243         { }
 244 };
 245
 246 static int __init reboot_init(void)
 247 {
 248         dmi_check_system(reboot_dmi_table);
 249         return 0;
 250 }
 251 core_initcall(reboot_init);
 252
 253 /* The following code and data reboots the machine by switching to real
 254    mode and jumping to the BIOS reset entry point, as if the CPU has
 255    really been reset.  The previous version asked the keyboard
 256    controller to pulse the CPU reset line, which is more thorough, but
 257    doesn't work with at least one type of 486 motherboard.  It is easy
 258    to stop this code working; hence the copious comments. */
 259 static const unsigned long long
 260 real_mode_gdt_entries [3] =
 261 {
 262         0x0000000000000000ULL,  /* Null descriptor */
 263         0x00009b000000ffffULL,  /* 16-bit real-mode 64k code at 0x00000000 */
 264         0x000093000100ffffULL   /* 16-bit real-mode 64k data at 0x00000100 */
 265 };
 266
 267 static const struct desc_ptr
 268 real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, (long)real_mode_gdt_entries },
 269 real_mode_idt = { 0x3ff, 0 };
 270
 271 /* This is 16-bit protected mode code to disable paging and the cache,
 272    switch to real mode and jump to the BIOS reset code.
 273
 274    The instruction that switches to real mode by writing to CR0 must be
 275    followed immediately by a far jump instruction, which set CS to a
 276    valid value for real mode, and flushes the prefetch queue to avoid
 277    running instructions that have already been decoded in protected
 278    mode.
 279
 280    Clears all the flags except ET, especially PG (paging), PE
 281    (protected-mode enable) and TS (task switch for coprocessor state
 282    save).  Flushes the TLB after paging has been disabled.  Sets CD and
 283    NW, to disable the cache on a 486, and invalidates the cache.  This
 284    is more like the state of a 486 after reset.  I don't know if
 285    something else should be done for other chips.
 286
 287    More could be done here to set up the registers as if a CPU reset had
 288    occurred; hopefully real BIOSs don't assume much. */
 289 static const unsigned char real_mode_switch [] =
 290 {
 291         0x66, 0x0f, 0x20, 0xc0,                 /*    movl  %cr0,%eax        */
 292         0x66, 0x83, 0xe0, 0x11,                 /*    andl  $0x00000011,%eax */
 293         0x66, 0x0d, 0x00, 0x00, 0x00, 0x60,     /*    orl   $0x60000000,%eax */
 294         0x66, 0x0f, 0x22, 0xc0,                 /*    movl  %eax,%cr0        */
 295         0x66, 0x0f, 0x22, 0xd8,                 /*    movl  %eax,%cr3        */
 296         0x66, 0x0f, 0x20, 0xc3,                 /*    movl  %cr0,%ebx        */
 297         0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60,       /*    andl  $0x60000000,%ebx */
 298         0x74, 0x02,                             /*    jz    f                */
 299         0x0f, 0x09,                             /*    wbinvd                 */
 300         0x24, 0x10,                             /* f: andb  $0x10,al         */
 301         0x66, 0x0f, 0x22, 0xc0                  /*    movl  %eax,%cr0        */
 302 };
 303 static const unsigned char jump_to_bios [] =
 304 {
 305         0xea, 0x00, 0x00, 0xff, 0xff            /*    ljmp  $0xffff,$0x0000  */
 306 };
 307
 308 /*
 309  * Switch to real mode and then execute the code
 310  * specified by the code and length parameters.
 311  * We assume that length will aways be less that 100!
 312  */
 313 void machine_real_restart(const unsigned char *code, int length)
 314 {
 315         local_irq_disable();
 316
 317         /* Write zero to CMOS register number 0x0f, which the BIOS POST
 318            routine will recognize as telling it to do a proper reboot.  (Well
 319            that's what this book in front of me says -- it may only apply to
 320            the Phoenix BIOS though, it's not clear).  At the same time,
 321            disable NMIs by setting the top bit in the CMOS address register,
 322            as we're about to do peculiar things to the CPU.  I'm not sure if
 323            `outb_p' is needed instead of just `outb'.  Use it to be on the
 324            safe side.  (Yes, CMOS_WRITE does outb_p's. -  Paul G.)
 325          */
 326         spin_lock(&rtc_lock);
 327         CMOS_WRITE(0x00, 0x8f);
 328         spin_unlock(&rtc_lock);
 329
 330         /* Remap the kernel at virtual address zero, as well as offset zero
 331            from the kernel segment.  This assumes the kernel segment starts at
 332            virtual address PAGE_OFFSET. */
 333         memcpy(swapper_pg_dir, swapper_pg_dir + KERNEL_PGD_BOUNDARY,
 334                 sizeof(swapper_pg_dir [0]) * KERNEL_PGD_PTRS);
 335
 336         /*
 337          * Use `swapper_pg_dir' as our page directory.
 338          */
 339         load_cr3(swapper_pg_dir);
 340
 341         /* Write 0x1234 to absolute memory location 0x472.  The BIOS reads
 342            this on booting to tell it to "Bypass memory test (also warm
 343            boot)".  This seems like a fairly standard thing that gets set by
 344            REBOOT.COM programs, and the previous reset routine did this
 345            too. */
 346         *((unsigned short *)0x472) = reboot_mode;
 347
 348         /* For the switch to real mode, copy some code to low memory.  It has
 349            to be in the first 64k because it is running in 16-bit mode, and it
 350            has to have the same physical and virtual address, because it turns
 351            off paging.  Copy it near the end of the first page, out of the way
 352            of BIOS variables. */
 353         memcpy((void *)(0x1000 - sizeof(real_mode_switch) - 100),
 354                 real_mode_switch, sizeof (real_mode_switch));
 355         memcpy((void *)(0x1000 - 100), code, length);
 356
 357         /* Set up the IDT for real mode. */
 358         load_idt(&real_mode_idt);
 359
 360         /* Set up a GDT from which we can load segment descriptors for real
 361            mode.  The GDT is not used in real mode; it is just needed here to
 362            prepare the descriptors. */
 363         load_gdt(&real_mode_gdt);
 364
 365         /* Load the data segment registers, and thus the descriptors ready for
 366            real mode.  The base address of each segment is 0x100, 16 times the
 367            selector value being loaded here.  This is so that the segment
 368            registers don't have to be reloaded after switching to real mode:
 369            the values are consistent for real mode operation already. */
 370         __asm__ __volatile__ ("movl $0x0010,%%eax\n"
 371                                 "\tmovl %%eax,%%ds\n"
 372                                 "\tmovl %%eax,%%es\n"
 373                                 "\tmovl %%eax,%%fs\n"
 374                                 "\tmovl %%eax,%%gs\n"
 375                                 "\tmovl %%eax,%%ss" : : : "eax");
 376
 377         /* Jump to the 16-bit code that we copied earlier.  It disables paging
 378            and the cache, switches to real mode, and jumps to the BIOS reset
 379            entry point. */
 380         __asm__ __volatile__ ("ljmp $0x0008,%0"
 381                                 :
 382                                 : "i" ((void *)(0x1000 - sizeof (real_mode_switch) - 100)));
 383 }
 384 #ifdef CONFIG_APM_MODULE
 385 EXPORT_SYMBOL(machine_real_restart);
 386 #endif
 387
 388 #endif /* CONFIG_X86_32 */
 389
 390 static inline void kb_wait(void)
 391 {
 392         int i;
 393
 394         for (i = 0; i < 0x10000; i++) {
 395                 if ((inb(0x64) & 0x02) == 0)
 396                         break;
 397                 udelay(2);
 398         }
 399 }
 400
 401 static void vmxoff_nmi(int cpu, struct die_args *args)
 402 {
 403         cpu_emergency_vmxoff();
 404 }
 405
 406 /* Use NMIs as IPIs to tell all CPUs to disable virtualization
 407  */
 408 static void emergency_vmx_disable_all(void)
 409 {
 410         /* Just make sure we won't change CPUs while doing this */
 411         local_irq_disable();
 412
 413         /* We need to disable VMX on all CPUs before rebooting, otherwise
 414          * we risk hanging up the machine, because the CPU ignore INIT
 415          * signals when VMX is enabled.
 416          *
 417          * We can't take any locks and we may be on an inconsistent
 418          * state, so we use NMIs as IPIs to tell the other CPUs to disable
 419          * VMX and halt.
 420          *
 421          * For safety, we will avoid running the nmi_shootdown_cpus()
 422          * stuff unnecessarily, but we don't have a way to check
 423          * if other CPUs have VMX enabled. So we will call it only if the
 424          * CPU we are running on has VMX enabled.
 425          *
 426          * We will miss cases where VMX is not enabled on all CPUs. This
 427          * shouldn't do much harm because KVM always enable VMX on all
 428          * CPUs anyway. But we can miss it on the small window where KVM
 429          * is still enabling VMX.
 430          */
 431         if (cpu_has_vmx() && cpu_vmx_enabled()) {
 432                 /* Disable VMX on this CPU.
 433                  */
 434                 cpu_vmxoff();
 435
 436                 /* Halt and disable VMX on the other CPUs */
 437                 nmi_shootdown_cpus(vmxoff_nmi);
 438
 439         }
 440 }
 441
 442
 443 void __attribute__((weak)) mach_reboot_fixups(void)
 444 {
 445 }
 446
 447 static void native_machine_emergency_restart(void)
 448 {
 449         int i;
 450
 451         if (reboot_emergency)
 452                 emergency_vmx_disable_all();
 453
 454         /* Tell the BIOS if we want cold or warm reboot */
 455         *((unsigned short *)__va(0x472)) = reboot_mode;
 456
 457         for (;;) {
 458                 /* Could also try the reset bit in the Hammer NB */
 459                 switch (reboot_type) {
 460                 case BOOT_KBD:
 461                         mach_reboot_fixups(); /* for board specific fixups */
 462
 463                         for (i = 0; i < 10; i++) {
 464                                 kb_wait();
 465                                 udelay(50);
 466                                 outb(0xfe, 0x64); /* pulse reset low */
 467                                 udelay(50);
 468                         }
 469
 470                 case BOOT_TRIPLE:
 471                         load_idt(&no_idt);
 472                         __asm__ __volatile__("int3");
 473
 474                         reboot_type = BOOT_KBD;
 475                         break;
 476
 477 #ifdef CONFIG_X86_32
 478                 case BOOT_BIOS:
 479                         machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
 480
 481                         reboot_type = BOOT_KBD;
 482                         break;
 483 #endif
 484
 485                 case BOOT_ACPI:
 486                         acpi_reboot();
 487                         reboot_type = BOOT_KBD;
 488                         break;
 489
 490                 case BOOT_EFI:
 491                         if (efi_enabled)
 492                                 efi.reset_system(reboot_mode ?
 493                                                  EFI_RESET_WARM :
 494                                                  EFI_RESET_COLD,
 495                                                  EFI_SUCCESS, 0, NULL);
 496                         reboot_type = BOOT_KBD;
 497                         break;
 498
 499                 case BOOT_CF9:
 500                         port_cf9_safe = true;
 501                         /* fall through */
 502
 503                 case BOOT_CF9_COND:
 504                         if (port_cf9_safe) {
 505                                 u8 cf9 = inb(0xcf9) & ~6;
 506                                 outb(cf9|2, 0xcf9); /* Request hard reset */
 507                                 udelay(50);
 508                                 outb(cf9|6, 0xcf9); /* Actually do the reset */
 509                                 udelay(50);
 510                         }
 511                         reboot_type = BOOT_KBD;
 512                         break;
 513                 }
 514         }
 515 }
 516
 517 void native_machine_shutdown(void)
 518 {
 519         /* Stop the cpus and apics */
 520 #ifdef CONFIG_SMP
 521
 522         /* The boot cpu is always logical cpu 0 */
 523         int reboot_cpu_id = 0;
 524
 525 #ifdef CONFIG_X86_32
 526         /* See if there has been given a command line override */
 527         if ((reboot_cpu != -1) && (reboot_cpu < nr_cpu_ids) &&
 528                 cpu_online(reboot_cpu))
 529                 reboot_cpu_id = reboot_cpu;
 530 #endif
 531
 532         /* Make certain the cpu I'm about to reboot on is online */
 533         if (!cpu_online(reboot_cpu_id))
 534                 reboot_cpu_id = smp_processor_id();
 535
 536         /* Make certain I only run on the appropriate processor */
 537         set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id));
 538
 539         /* O.K Now that I'm on the appropriate processor,
 540          * stop all of the others.
 541          */
 542         smp_send_stop();
 543 #endif
 544
 545         lapic_shutdown();
 546
 547 #ifdef CONFIG_X86_IO_APIC
 548         disable_IO_APIC();
 549 #endif
 550
 551 #ifdef CONFIG_HPET_TIMER
 552         hpet_disable();
 553 #endif
 554
 555 #ifdef CONFIG_X86_64
 556         pci_iommu_shutdown();
 557 #endif
 558 }
 559
 560 static void __machine_emergency_restart(int emergency)
 561 {
 562         reboot_emergency = emergency;
 563         machine_ops.emergency_restart();
 564 }
 565
 566 static void native_machine_restart(char *__unused)
 567 {
 568         printk("machine restart\n");
 569
 570         if (!reboot_force)
 571                 machine_shutdown();
 572         __machine_emergency_restart(0);
 573 }
 574
 575 static void native_machine_halt(void)
 576 {
 577         /* stop other cpus and apics */
 578         machine_shutdown();
 579
 580         /* stop this cpu */
 581         stop_this_cpu(NULL);
 582 }
 583
 584 static void native_machine_power_off(void)
 585 {
 586         if (pm_power_off) {
 587                 if (!reboot_force)
 588                         machine_shutdown();
 589                 pm_power_off();
 590         }
 591 }
 592
 593 struct machine_ops machine_ops = {
 594         .power_off = native_machine_power_off,
 595         .shutdown = native_machine_shutdown,
 596         .emergency_restart = native_machine_emergency_restart,
 597         .restart = native_machine_restart,
 598         .halt = native_machine_halt,
 599 #ifdef CONFIG_KEXEC
 600         .crash_shutdown = native_machine_crash_shutdown,
 601 #endif
 602 };
 603
 604 void machine_power_off(void)
 605 {
 606         machine_ops.power_off();
 607 }
 608
 609 void machine_shutdown(void)
 610 {
 611         machine_ops.shutdown();
 612 }
 613
 614 void machine_emergency_restart(void)
 615 {
 616         __machine_emergency_restart(1);
 617 }
 618
 619 void machine_restart(char *cmd)
 620 {
 621         machine_ops.restart(cmd);
 622 }
 623
 624 void machine_halt(void)
 625 {
 626         machine_ops.halt();
 627 }
 628
 629 #ifdef CONFIG_KEXEC
 630 void machine_crash_shutdown(struct pt_regs *regs)
 631 {
 632         machine_ops.crash_shutdown(regs);
 633 }
 634 #endif
 635
 636
 637 #if defined(CONFIG_SMP)
 638
 639 /* This keeps a track of which one is crashing cpu. */
 640 static int crashing_cpu;
 641 static nmi_shootdown_cb shootdown_callback;
 642
 643 static atomic_t waiting_for_crash_ipi;
 644
 645 static int crash_nmi_callback(struct notifier_block *self,
 646                         unsigned long val, void *data)
 647 {
 648         int cpu;
 649
 650         if (val != DIE_NMI_IPI)
 651                 return NOTIFY_OK;
 652
 653         cpu = raw_smp_processor_id();
 654
 655         /* Don't do anything if this handler is invoked on crashing cpu.
 656          * Otherwise, system will completely hang. Crashing cpu can get
 657          * an NMI if system was initially booted with nmi_watchdog parameter.
 658          */
 659         if (cpu == crashing_cpu)
 660                 return NOTIFY_STOP;
 661         local_irq_disable();
 662
 663         shootdown_callback(cpu, (struct die_args *)data);
 664
 665         atomic_dec(&waiting_for_crash_ipi);
 666         /* Assume hlt works */
 667         halt();
 668         for (;;)
 669                 cpu_relax();
 670
 671         return 1;
 672 }
 673
 674 static void smp_send_nmi_allbutself(void)
 675 {
 676         apic->send_IPI_allbutself(NMI_VECTOR);
 677 }
 678
 679 static struct notifier_block crash_nmi_nb = {
 680         .notifier_call = crash_nmi_callback,
 681 };
 682
 683 /* Halt all other CPUs, calling the specified function on each of them
 684  *
 685  * This function can be used to halt all other CPUs on crash
 686  * or emergency reboot time. The function passed as parameter
 687  * will be called inside a NMI handler on all CPUs.
 688  */
 689 void nmi_shootdown_cpus(nmi_shootdown_cb callback)
 690 {
 691         unsigned long msecs;
 692         local_irq_disable();
 693
 694         /* Make a note of crashing cpu. Will be used in NMI callback.*/
 695         crashing_cpu = safe_smp_processor_id();
 696
 697         shootdown_callback = callback;
 698
 699         atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
 700         /* Would it be better to replace the trap vector here? */
 701         if (register_die_notifier(&crash_nmi_nb))
 702                 return;         /* return what? */
 703         /* Ensure the new callback function is set before sending
 704          * out the NMI
 705          */
 706         wmb();
 707
 708         smp_send_nmi_allbutself();
 709
 710         msecs = 1000; /* Wait at most a second for the other cpus to stop */
 711         while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
 712                 mdelay(1);
 713                 msecs--;
 714         }
 715
 716         /* Leave the nmi callback set */
 717 }
 718 #else /* !CONFIG_SMP */
 719 void nmi_shootdown_cpus(nmi_shootdown_cb callback)
 720 {
 721         /* No other CPUs to shoot down */
 722 }
 723 #endif