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