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 { } 228 }; 229 230 static int __init reboot_init(void) 231 { 232 dmi_check_system(reboot_dmi_table); 233 return 0; 234 } 235 core_initcall(reboot_init); 236 237 /* The following code and data reboots the machine by switching to real 238 mode and jumping to the BIOS reset entry point, as if the CPU has 239 really been reset. The previous version asked the keyboard 240 controller to pulse the CPU reset line, which is more thorough, but 241 doesn't work with at least one type of 486 motherboard. It is easy 242 to stop this code working; hence the copious comments. */ 243 static const unsigned long long 244 real_mode_gdt_entries [3] = 245 { 246 0x0000000000000000ULL, /* Null descriptor */ 247 0x00009b000000ffffULL, /* 16-bit real-mode 64k code at 0x00000000 */ 248 0x000093000100ffffULL /* 16-bit real-mode 64k data at 0x00000100 */ 249 }; 250 251 static const struct desc_ptr 252 real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, (long)real_mode_gdt_entries }, 253 real_mode_idt = { 0x3ff, 0 }; 254 255 /* This is 16-bit protected mode code to disable paging and the cache, 256 switch to real mode and jump to the BIOS reset code. 257 258 The instruction that switches to real mode by writing to CR0 must be 259 followed immediately by a far jump instruction, which set CS to a 260 valid value for real mode, and flushes the prefetch queue to avoid 261 running instructions that have already been decoded in protected 262 mode. 263 264 Clears all the flags except ET, especially PG (paging), PE 265 (protected-mode enable) and TS (task switch for coprocessor state 266 save). Flushes the TLB after paging has been disabled. Sets CD and 267 NW, to disable the cache on a 486, and invalidates the cache. This 268 is more like the state of a 486 after reset. I don't know if 269 something else should be done for other chips. 270 271 More could be done here to set up the registers as if a CPU reset had 272 occurred; hopefully real BIOSs don't assume much. */ 273 static const unsigned char real_mode_switch [] = 274 { 275 0x66, 0x0f, 0x20, 0xc0, /* movl %cr0,%eax */ 276 0x66, 0x83, 0xe0, 0x11, /* andl $0x00000011,%eax */ 277 0x66, 0x0d, 0x00, 0x00, 0x00, 0x60, /* orl $0x60000000,%eax */ 278 0x66, 0x0f, 0x22, 0xc0, /* movl %eax,%cr0 */ 279 0x66, 0x0f, 0x22, 0xd8, /* movl %eax,%cr3 */ 280 0x66, 0x0f, 0x20, 0xc3, /* movl %cr0,%ebx */ 281 0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60, /* andl $0x60000000,%ebx */ 282 0x74, 0x02, /* jz f */ 283 0x0f, 0x09, /* wbinvd */ 284 0x24, 0x10, /* f: andb $0x10,al */ 285 0x66, 0x0f, 0x22, 0xc0 /* movl %eax,%cr0 */ 286 }; 287 static const unsigned char jump_to_bios [] = 288 { 289 0xea, 0x00, 0x00, 0xff, 0xff /* ljmp $0xffff,$0x0000 */ 290 }; 291 292 /* 293 * Switch to real mode and then execute the code 294 * specified by the code and length parameters. 295 * We assume that length will aways be less that 100! 296 */ 297 void machine_real_restart(const unsigned char *code, int length) 298 { 299 local_irq_disable(); 300 301 /* Write zero to CMOS register number 0x0f, which the BIOS POST 302 routine will recognize as telling it to do a proper reboot. (Well 303 that's what this book in front of me says -- it may only apply to 304 the Phoenix BIOS though, it's not clear). At the same time, 305 disable NMIs by setting the top bit in the CMOS address register, 306 as we're about to do peculiar things to the CPU. I'm not sure if 307 `outb_p' is needed instead of just `outb'. Use it to be on the 308 safe side. (Yes, CMOS_WRITE does outb_p's. - Paul G.) 309 */ 310 spin_lock(&rtc_lock); 311 CMOS_WRITE(0x00, 0x8f); 312 spin_unlock(&rtc_lock); 313 314 /* Remap the kernel at virtual address zero, as well as offset zero 315 from the kernel segment. This assumes the kernel segment starts at 316 virtual address PAGE_OFFSET. */ 317 memcpy(swapper_pg_dir, swapper_pg_dir + KERNEL_PGD_BOUNDARY, 318 sizeof(swapper_pg_dir [0]) * KERNEL_PGD_PTRS); 319 320 /* 321 * Use `swapper_pg_dir' as our page directory. 322 */ 323 load_cr3(swapper_pg_dir); 324 325 /* Write 0x1234 to absolute memory location 0x472. The BIOS reads 326 this on booting to tell it to "Bypass memory test (also warm 327 boot)". This seems like a fairly standard thing that gets set by 328 REBOOT.COM programs, and the previous reset routine did this 329 too. */ 330 *((unsigned short *)0x472) = reboot_mode; 331 332 /* For the switch to real mode, copy some code to low memory. It has 333 to be in the first 64k because it is running in 16-bit mode, and it 334 has to have the same physical and virtual address, because it turns 335 off paging. Copy it near the end of the first page, out of the way 336 of BIOS variables. */ 337 memcpy((void *)(0x1000 - sizeof(real_mode_switch) - 100), 338 real_mode_switch, sizeof (real_mode_switch)); 339 memcpy((void *)(0x1000 - 100), code, length); 340 341 /* Set up the IDT for real mode. */ 342 load_idt(&real_mode_idt); 343 344 /* Set up a GDT from which we can load segment descriptors for real 345 mode. The GDT is not used in real mode; it is just needed here to 346 prepare the descriptors. */ 347 load_gdt(&real_mode_gdt); 348 349 /* Load the data segment registers, and thus the descriptors ready for 350 real mode. The base address of each segment is 0x100, 16 times the 351 selector value being loaded here. This is so that the segment 352 registers don't have to be reloaded after switching to real mode: 353 the values are consistent for real mode operation already. */ 354 __asm__ __volatile__ ("movl $0x0010,%%eax\n" 355 "\tmovl %%eax,%%ds\n" 356 "\tmovl %%eax,%%es\n" 357 "\tmovl %%eax,%%fs\n" 358 "\tmovl %%eax,%%gs\n" 359 "\tmovl %%eax,%%ss" : : : "eax"); 360 361 /* Jump to the 16-bit code that we copied earlier. It disables paging 362 and the cache, switches to real mode, and jumps to the BIOS reset 363 entry point. */ 364 __asm__ __volatile__ ("ljmp $0x0008,%0" 365 : 366 : "i" ((void *)(0x1000 - sizeof (real_mode_switch) - 100))); 367 } 368 #ifdef CONFIG_APM_MODULE 369 EXPORT_SYMBOL(machine_real_restart); 370 #endif 371 372 #endif /* CONFIG_X86_32 */ 373 374 static inline void kb_wait(void) 375 { 376 int i; 377 378 for (i = 0; i < 0x10000; i++) { 379 if ((inb(0x64) & 0x02) == 0) 380 break; 381 udelay(2); 382 } 383 } 384 385 static void vmxoff_nmi(int cpu, struct die_args *args) 386 { 387 cpu_emergency_vmxoff(); 388 } 389 390 /* Use NMIs as IPIs to tell all CPUs to disable virtualization 391 */ 392 static void emergency_vmx_disable_all(void) 393 { 394 /* Just make sure we won't change CPUs while doing this */ 395 local_irq_disable(); 396 397 /* We need to disable VMX on all CPUs before rebooting, otherwise 398 * we risk hanging up the machine, because the CPU ignore INIT 399 * signals when VMX is enabled. 400 * 401 * We can't take any locks and we may be on an inconsistent 402 * state, so we use NMIs as IPIs to tell the other CPUs to disable 403 * VMX and halt. 404 * 405 * For safety, we will avoid running the nmi_shootdown_cpus() 406 * stuff unnecessarily, but we don't have a way to check 407 * if other CPUs have VMX enabled. So we will call it only if the 408 * CPU we are running on has VMX enabled. 409 * 410 * We will miss cases where VMX is not enabled on all CPUs. This 411 * shouldn't do much harm because KVM always enable VMX on all 412 * CPUs anyway. But we can miss it on the small window where KVM 413 * is still enabling VMX. 414 */ 415 if (cpu_has_vmx() && cpu_vmx_enabled()) { 416 /* Disable VMX on this CPU. 417 */ 418 cpu_vmxoff(); 419 420 /* Halt and disable VMX on the other CPUs */ 421 nmi_shootdown_cpus(vmxoff_nmi); 422 423 } 424 } 425 426 427 void __attribute__((weak)) mach_reboot_fixups(void) 428 { 429 } 430 431 static void native_machine_emergency_restart(void) 432 { 433 int i; 434 435 if (reboot_emergency) 436 emergency_vmx_disable_all(); 437 438 /* Tell the BIOS if we want cold or warm reboot */ 439 *((unsigned short *)__va(0x472)) = reboot_mode; 440 441 for (;;) { 442 /* Could also try the reset bit in the Hammer NB */ 443 switch (reboot_type) { 444 case BOOT_KBD: 445 mach_reboot_fixups(); /* for board specific fixups */ 446 447 for (i = 0; i < 10; i++) { 448 kb_wait(); 449 udelay(50); 450 outb(0xfe, 0x64); /* pulse reset low */ 451 udelay(50); 452 } 453 454 case BOOT_TRIPLE: 455 load_idt(&no_idt); 456 __asm__ __volatile__("int3"); 457 458 reboot_type = BOOT_KBD; 459 break; 460 461 #ifdef CONFIG_X86_32 462 case BOOT_BIOS: 463 machine_real_restart(jump_to_bios, sizeof(jump_to_bios)); 464 465 reboot_type = BOOT_KBD; 466 break; 467 #endif 468 469 case BOOT_ACPI: 470 acpi_reboot(); 471 reboot_type = BOOT_KBD; 472 break; 473 474 case BOOT_EFI: 475 if (efi_enabled) 476 efi.reset_system(reboot_mode ? 477 EFI_RESET_WARM : 478 EFI_RESET_COLD, 479 EFI_SUCCESS, 0, NULL); 480 reboot_type = BOOT_KBD; 481 break; 482 483 case BOOT_CF9: 484 port_cf9_safe = true; 485 /* fall through */ 486 487 case BOOT_CF9_COND: 488 if (port_cf9_safe) { 489 u8 cf9 = inb(0xcf9) & ~6; 490 outb(cf9|2, 0xcf9); /* Request hard reset */ 491 udelay(50); 492 outb(cf9|6, 0xcf9); /* Actually do the reset */ 493 udelay(50); 494 } 495 reboot_type = BOOT_KBD; 496 break; 497 } 498 } 499 } 500 501 void native_machine_shutdown(void) 502 { 503 /* Stop the cpus and apics */ 504 #ifdef CONFIG_SMP 505 506 /* The boot cpu is always logical cpu 0 */ 507 int reboot_cpu_id = 0; 508 509 #ifdef CONFIG_X86_32 510 /* See if there has been given a command line override */ 511 if ((reboot_cpu != -1) && (reboot_cpu < nr_cpu_ids) && 512 cpu_online(reboot_cpu)) 513 reboot_cpu_id = reboot_cpu; 514 #endif 515 516 /* Make certain the cpu I'm about to reboot on is online */ 517 if (!cpu_online(reboot_cpu_id)) 518 reboot_cpu_id = smp_processor_id(); 519 520 /* Make certain I only run on the appropriate processor */ 521 set_cpus_allowed_ptr(current, cpumask_of(reboot_cpu_id)); 522 523 /* O.K Now that I'm on the appropriate processor, 524 * stop all of the others. 525 */ 526 smp_send_stop(); 527 #endif 528 529 lapic_shutdown(); 530 531 #ifdef CONFIG_X86_IO_APIC 532 disable_IO_APIC(); 533 #endif 534 535 #ifdef CONFIG_HPET_TIMER 536 hpet_disable(); 537 #endif 538 539 #ifdef CONFIG_X86_64 540 pci_iommu_shutdown(); 541 #endif 542 } 543 544 static void __machine_emergency_restart(int emergency) 545 { 546 reboot_emergency = emergency; 547 machine_ops.emergency_restart(); 548 } 549 550 static void native_machine_restart(char *__unused) 551 { 552 printk("machine restart\n"); 553 554 if (!reboot_force) 555 machine_shutdown(); 556 __machine_emergency_restart(0); 557 } 558 559 static void native_machine_halt(void) 560 { 561 /* stop other cpus and apics */ 562 machine_shutdown(); 563 564 /* stop this cpu */ 565 stop_this_cpu(NULL); 566 } 567 568 static void native_machine_power_off(void) 569 { 570 if (pm_power_off) { 571 if (!reboot_force) 572 machine_shutdown(); 573 pm_power_off(); 574 } 575 } 576 577 struct machine_ops machine_ops = { 578 .power_off = native_machine_power_off, 579 .shutdown = native_machine_shutdown, 580 .emergency_restart = native_machine_emergency_restart, 581 .restart = native_machine_restart, 582 .halt = native_machine_halt, 583 #ifdef CONFIG_KEXEC 584 .crash_shutdown = native_machine_crash_shutdown, 585 #endif 586 }; 587 588 void machine_power_off(void) 589 { 590 machine_ops.power_off(); 591 } 592 593 void machine_shutdown(void) 594 { 595 machine_ops.shutdown(); 596 } 597 598 void machine_emergency_restart(void) 599 { 600 __machine_emergency_restart(1); 601 } 602 603 void machine_restart(char *cmd) 604 { 605 machine_ops.restart(cmd); 606 } 607 608 void machine_halt(void) 609 { 610 machine_ops.halt(); 611 } 612 613 #ifdef CONFIG_KEXEC 614 void machine_crash_shutdown(struct pt_regs *regs) 615 { 616 machine_ops.crash_shutdown(regs); 617 } 618 #endif 619 620 621 #if defined(CONFIG_SMP) 622 623 /* This keeps a track of which one is crashing cpu. */ 624 static int crashing_cpu; 625 static nmi_shootdown_cb shootdown_callback; 626 627 static atomic_t waiting_for_crash_ipi; 628 629 static int crash_nmi_callback(struct notifier_block *self, 630 unsigned long val, void *data) 631 { 632 int cpu; 633 634 if (val != DIE_NMI_IPI) 635 return NOTIFY_OK; 636 637 cpu = raw_smp_processor_id(); 638 639 /* Don't do anything if this handler is invoked on crashing cpu. 640 * Otherwise, system will completely hang. Crashing cpu can get 641 * an NMI if system was initially booted with nmi_watchdog parameter. 642 */ 643 if (cpu == crashing_cpu) 644 return NOTIFY_STOP; 645 local_irq_disable(); 646 647 shootdown_callback(cpu, (struct die_args *)data); 648 649 atomic_dec(&waiting_for_crash_ipi); 650 /* Assume hlt works */ 651 halt(); 652 for (;;) 653 cpu_relax(); 654 655 return 1; 656 } 657 658 static void smp_send_nmi_allbutself(void) 659 { 660 apic->send_IPI_allbutself(NMI_VECTOR); 661 } 662 663 static struct notifier_block crash_nmi_nb = { 664 .notifier_call = crash_nmi_callback, 665 }; 666 667 /* Halt all other CPUs, calling the specified function on each of them 668 * 669 * This function can be used to halt all other CPUs on crash 670 * or emergency reboot time. The function passed as parameter 671 * will be called inside a NMI handler on all CPUs. 672 */ 673 void nmi_shootdown_cpus(nmi_shootdown_cb callback) 674 { 675 unsigned long msecs; 676 local_irq_disable(); 677 678 /* Make a note of crashing cpu. Will be used in NMI callback.*/ 679 crashing_cpu = safe_smp_processor_id(); 680 681 shootdown_callback = callback; 682 683 atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); 684 /* Would it be better to replace the trap vector here? */ 685 if (register_die_notifier(&crash_nmi_nb)) 686 return; /* return what? */ 687 /* Ensure the new callback function is set before sending 688 * out the NMI 689 */ 690 wmb(); 691 692 smp_send_nmi_allbutself(); 693 694 msecs = 1000; /* Wait at most a second for the other cpus to stop */ 695 while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { 696 mdelay(1); 697 msecs--; 698 } 699 700 /* Leave the nmi callback set */ 701 } 702 #else /* !CONFIG_SMP */ 703 void nmi_shootdown_cpus(nmi_shootdown_cb callback) 704 { 705 /* No other CPUs to shoot down */ 706 } 707 #endif 708