1 // SPDX-License-Identifier: GPL-2.0
2 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
4 #include <linux/export.h>
5 #include <linux/reboot.h>
6 #include <linux/init.h>
10 #include <linux/sched.h>
11 #include <linux/tboot.h>
12 #include <linux/delay.h>
13 #include <linux/objtool.h>
14 #include <linux/pgtable.h>
15 #include <acpi/reboot.h>
18 #include <asm/io_apic.h>
21 #include <asm/proto.h>
22 #include <asm/reboot_fixups.h>
23 #include <asm/reboot.h>
24 #include <asm/pci_x86.h>
25 #include <asm/virtext.h>
30 #include <linux/ctype.h>
31 #include <linux/mc146818rtc.h>
32 #include <asm/realmode.h>
33 #include <asm/x86_init.h>
37 * Power off function, if any
39 void (*pm_power_off)(void);
40 EXPORT_SYMBOL(pm_power_off);
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
47 static int reboot_emergency;
49 /* This is set by the PCI code if either type 1 or type 2 PCI is detected */
50 bool port_cf9_safe = false;
53 * Reboot options and system auto-detection code provided by
54 * Dell Inc. so their systems "just work". :-)
58 * Some machines require the "reboot=a" commandline options
60 static int __init set_acpi_reboot(const struct dmi_system_id *d)
62 if (reboot_type != BOOT_ACPI) {
63 reboot_type = BOOT_ACPI;
64 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
71 * Some machines require the "reboot=b" or "reboot=k" commandline options,
72 * this quirk makes that automatic.
74 static int __init set_bios_reboot(const struct dmi_system_id *d)
76 if (reboot_type != BOOT_BIOS) {
77 reboot_type = BOOT_BIOS;
78 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
85 * Some machines don't handle the default ACPI reboot method and
86 * require the EFI reboot method:
88 static int __init set_efi_reboot(const struct dmi_system_id *d)
90 if (reboot_type != BOOT_EFI && !efi_runtime_disabled()) {
91 reboot_type = BOOT_EFI;
92 pr_info("%s series board detected. Selecting EFI-method for reboot.\n", d->ident);
97 void __noreturn machine_real_restart(unsigned int type)
102 * Write zero to CMOS register number 0x0f, which the BIOS POST
103 * routine will recognize as telling it to do a proper reboot. (Well
104 * that's what this book in front of me says -- it may only apply to
105 * the Phoenix BIOS though, it's not clear). At the same time,
106 * disable NMIs by setting the top bit in the CMOS address register,
107 * as we're about to do peculiar things to the CPU. I'm not sure if
108 * `outb_p' is needed instead of just `outb'. Use it to be on the
109 * safe side. (Yes, CMOS_WRITE does outb_p's. - Paul G.)
111 spin_lock(&rtc_lock);
112 CMOS_WRITE(0x00, 0x8f);
113 spin_unlock(&rtc_lock);
116 * Switch back to the initial page table.
119 load_cr3(initial_page_table);
121 write_cr3(real_mode_header->trampoline_pgd);
123 /* Exiting long mode will fail if CR4.PCIDE is set. */
124 if (boot_cpu_has(X86_FEATURE_PCID))
125 cr4_clear_bits(X86_CR4_PCIDE);
128 /* Jump to the identity-mapped low memory code */
130 asm volatile("jmpl *%0" : :
131 "rm" (real_mode_header->machine_real_restart_asm),
134 asm volatile("ljmpl *%0" : :
135 "m" (real_mode_header->machine_real_restart_asm),
140 #ifdef CONFIG_APM_MODULE
141 EXPORT_SYMBOL(machine_real_restart);
143 STACK_FRAME_NON_STANDARD(machine_real_restart);
146 * Some Apple MacBook and MacBookPro's needs reboot=p to be able to reboot
148 static int __init set_pci_reboot(const struct dmi_system_id *d)
150 if (reboot_type != BOOT_CF9_FORCE) {
151 reboot_type = BOOT_CF9_FORCE;
152 pr_info("%s series board detected. Selecting %s-method for reboots.\n",
158 static int __init set_kbd_reboot(const struct dmi_system_id *d)
160 if (reboot_type != BOOT_KBD) {
161 reboot_type = BOOT_KBD;
162 pr_info("%s series board detected. Selecting %s-method for reboot.\n",
169 * This is a single dmi_table handling all reboot quirks.
171 static const struct dmi_system_id reboot_dmi_table[] __initconst = {
174 { /* Handle reboot issue on Acer Aspire one */
175 .callback = set_kbd_reboot,
176 .ident = "Acer Aspire One A110",
178 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
179 DMI_MATCH(DMI_PRODUCT_NAME, "AOA110"),
182 { /* Handle reboot issue on Acer TravelMate X514-51T */
183 .callback = set_efi_reboot,
184 .ident = "Acer TravelMate X514-51T",
186 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
187 DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate X514-51T"),
192 { /* Handle problems with rebooting on Apple MacBook5 */
193 .callback = set_pci_reboot,
194 .ident = "Apple MacBook5",
196 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
197 DMI_MATCH(DMI_PRODUCT_NAME, "MacBook5"),
200 { /* Handle problems with rebooting on Apple MacBook6,1 */
201 .callback = set_pci_reboot,
202 .ident = "Apple MacBook6,1",
204 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
205 DMI_MATCH(DMI_PRODUCT_NAME, "MacBook6,1"),
208 { /* Handle problems with rebooting on Apple MacBookPro5 */
209 .callback = set_pci_reboot,
210 .ident = "Apple MacBookPro5",
212 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
213 DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro5"),
216 { /* Handle problems with rebooting on Apple Macmini3,1 */
217 .callback = set_pci_reboot,
218 .ident = "Apple Macmini3,1",
220 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
221 DMI_MATCH(DMI_PRODUCT_NAME, "Macmini3,1"),
224 { /* Handle problems with rebooting on the iMac9,1. */
225 .callback = set_pci_reboot,
226 .ident = "Apple iMac9,1",
228 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
229 DMI_MATCH(DMI_PRODUCT_NAME, "iMac9,1"),
232 { /* Handle problems with rebooting on the iMac10,1. */
233 .callback = set_pci_reboot,
234 .ident = "Apple iMac10,1",
236 DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
237 DMI_MATCH(DMI_PRODUCT_NAME, "iMac10,1"),
242 { /* Handle problems with rebooting on ASRock Q1900DC-ITX */
243 .callback = set_pci_reboot,
244 .ident = "ASRock Q1900DC-ITX",
246 DMI_MATCH(DMI_BOARD_VENDOR, "ASRock"),
247 DMI_MATCH(DMI_BOARD_NAME, "Q1900DC-ITX"),
252 { /* Handle problems with rebooting on ASUS P4S800 */
253 .callback = set_bios_reboot,
254 .ident = "ASUS P4S800",
256 DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."),
257 DMI_MATCH(DMI_BOARD_NAME, "P4S800"),
260 { /* Handle problems with rebooting on ASUS EeeBook X205TA */
261 .callback = set_acpi_reboot,
262 .ident = "ASUS EeeBook X205TA",
264 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
265 DMI_MATCH(DMI_PRODUCT_NAME, "X205TA"),
268 { /* Handle problems with rebooting on ASUS EeeBook X205TAW */
269 .callback = set_acpi_reboot,
270 .ident = "ASUS EeeBook X205TAW",
272 DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
273 DMI_MATCH(DMI_PRODUCT_NAME, "X205TAW"),
278 { /* Handle problems with rebooting on Certec BPC600 */
279 .callback = set_pci_reboot,
280 .ident = "Certec BPC600",
282 DMI_MATCH(DMI_SYS_VENDOR, "Certec"),
283 DMI_MATCH(DMI_PRODUCT_NAME, "BPC600"),
288 { /* Handle problems with rebooting on Dell DXP061 */
289 .callback = set_bios_reboot,
290 .ident = "Dell DXP061",
292 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
293 DMI_MATCH(DMI_PRODUCT_NAME, "Dell DXP061"),
296 { /* Handle problems with rebooting on Dell E520's */
297 .callback = set_bios_reboot,
298 .ident = "Dell E520",
300 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
301 DMI_MATCH(DMI_PRODUCT_NAME, "Dell DM061"),
304 { /* Handle problems with rebooting on the Latitude E5410. */
305 .callback = set_pci_reboot,
306 .ident = "Dell Latitude E5410",
308 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
309 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5410"),
312 { /* Handle problems with rebooting on the Latitude E5420. */
313 .callback = set_pci_reboot,
314 .ident = "Dell Latitude E5420",
316 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
317 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5420"),
320 { /* Handle problems with rebooting on the Latitude E6320. */
321 .callback = set_pci_reboot,
322 .ident = "Dell Latitude E6320",
324 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
325 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6320"),
328 { /* Handle problems with rebooting on the Latitude E6420. */
329 .callback = set_pci_reboot,
330 .ident = "Dell Latitude E6420",
332 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
333 DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6420"),
336 { /* Handle problems with rebooting on Dell Optiplex 330 with 0KP561 */
337 .callback = set_bios_reboot,
338 .ident = "Dell OptiPlex 330",
340 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
341 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 330"),
342 DMI_MATCH(DMI_BOARD_NAME, "0KP561"),
345 { /* Handle problems with rebooting on Dell Optiplex 360 with 0T656F */
346 .callback = set_bios_reboot,
347 .ident = "Dell OptiPlex 360",
349 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
350 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 360"),
351 DMI_MATCH(DMI_BOARD_NAME, "0T656F"),
354 { /* Handle problems with rebooting on Dell Optiplex 745's SFF */
355 .callback = set_bios_reboot,
356 .ident = "Dell OptiPlex 745",
358 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
359 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
362 { /* Handle problems with rebooting on Dell Optiplex 745's DFF */
363 .callback = set_bios_reboot,
364 .ident = "Dell OptiPlex 745",
366 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
367 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
368 DMI_MATCH(DMI_BOARD_NAME, "0MM599"),
371 { /* Handle problems with rebooting on Dell Optiplex 745 with 0KW626 */
372 .callback = set_bios_reboot,
373 .ident = "Dell OptiPlex 745",
375 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
376 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"),
377 DMI_MATCH(DMI_BOARD_NAME, "0KW626"),
380 { /* Handle problems with rebooting on Dell OptiPlex 760 with 0G919G */
381 .callback = set_bios_reboot,
382 .ident = "Dell OptiPlex 760",
384 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
385 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 760"),
386 DMI_MATCH(DMI_BOARD_NAME, "0G919G"),
389 { /* Handle problems with rebooting on the OptiPlex 990. */
390 .callback = set_pci_reboot,
391 .ident = "Dell OptiPlex 990 BIOS A0x",
393 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
394 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 990"),
395 DMI_MATCH(DMI_BIOS_VERSION, "A0"),
398 { /* Handle problems with rebooting on Dell 300's */
399 .callback = set_bios_reboot,
400 .ident = "Dell PowerEdge 300",
402 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
403 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 300/"),
406 { /* Handle problems with rebooting on Dell 1300's */
407 .callback = set_bios_reboot,
408 .ident = "Dell PowerEdge 1300",
410 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
411 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 1300/"),
414 { /* Handle problems with rebooting on Dell 2400's */
415 .callback = set_bios_reboot,
416 .ident = "Dell PowerEdge 2400",
418 DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
419 DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 2400"),
422 { /* Handle problems with rebooting on the Dell PowerEdge C6100. */
423 .callback = set_pci_reboot,
424 .ident = "Dell PowerEdge C6100",
426 DMI_MATCH(DMI_SYS_VENDOR, "Dell"),
427 DMI_MATCH(DMI_PRODUCT_NAME, "C6100"),
430 { /* Handle problems with rebooting on the Precision M6600. */
431 .callback = set_pci_reboot,
432 .ident = "Dell Precision M6600",
434 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
435 DMI_MATCH(DMI_PRODUCT_NAME, "Precision M6600"),
438 { /* Handle problems with rebooting on Dell T5400's */
439 .callback = set_bios_reboot,
440 .ident = "Dell Precision T5400",
442 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
443 DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T5400"),
446 { /* Handle problems with rebooting on Dell T7400's */
447 .callback = set_bios_reboot,
448 .ident = "Dell Precision T7400",
450 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
451 DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T7400"),
454 { /* Handle problems with rebooting on Dell XPS710 */
455 .callback = set_bios_reboot,
456 .ident = "Dell XPS710",
458 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
459 DMI_MATCH(DMI_PRODUCT_NAME, "Dell XPS710"),
462 { /* Handle problems with rebooting on Dell Optiplex 7450 AIO */
463 .callback = set_acpi_reboot,
464 .ident = "Dell OptiPlex 7450 AIO",
466 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
467 DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 7450 AIO"),
471 /* Hewlett-Packard */
472 { /* Handle problems with rebooting on HP laptops */
473 .callback = set_bios_reboot,
474 .ident = "HP Compaq Laptop",
476 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
477 DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq"),
481 { /* PCIe Wifi card isn't detected after reboot otherwise */
482 .callback = set_pci_reboot,
483 .ident = "Zotac ZBOX CI327 nano",
485 DMI_MATCH(DMI_SYS_VENDOR, "NA"),
486 DMI_MATCH(DMI_PRODUCT_NAME, "ZBOX-CI327NANO-GS-01"),
491 { /* Handle problems with rebooting on Sony VGN-Z540N */
492 .callback = set_bios_reboot,
493 .ident = "Sony VGN-Z540N",
495 DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
496 DMI_MATCH(DMI_PRODUCT_NAME, "VGN-Z540N"),
503 static int __init reboot_init(void)
508 * Only do the DMI check if reboot_type hasn't been overridden
509 * on the command line
515 * The DMI quirks table takes precedence. If no quirks entry
516 * matches and the ACPI Hardware Reduced bit is set and EFI
517 * runtime services are enabled, force EFI reboot.
519 rv = dmi_check_system(reboot_dmi_table);
521 if (!rv && efi_reboot_required() && !efi_runtime_disabled())
522 reboot_type = BOOT_EFI;
526 core_initcall(reboot_init);
528 static inline void kb_wait(void)
532 for (i = 0; i < 0x10000; i++) {
533 if ((inb(0x64) & 0x02) == 0)
539 static void vmxoff_nmi(int cpu, struct pt_regs *regs)
541 cpu_emergency_vmxoff();
544 /* Use NMIs as IPIs to tell all CPUs to disable virtualization */
545 static void emergency_vmx_disable_all(void)
547 /* Just make sure we won't change CPUs while doing this */
551 * Disable VMX on all CPUs before rebooting, otherwise we risk hanging
552 * the machine, because the CPU blocks INIT when it's in VMX root.
554 * We can't take any locks and we may be on an inconsistent state, so
555 * use NMIs as IPIs to tell the other CPUs to exit VMX root and halt.
557 * Do the NMI shootdown even if VMX if off on _this_ CPU, as that
558 * doesn't prevent a different CPU from being in VMX root operation.
561 /* Safely force _this_ CPU out of VMX root operation. */
562 __cpu_emergency_vmxoff();
564 /* Halt and exit VMX root operation on the other CPUs. */
565 nmi_shootdown_cpus(vmxoff_nmi);
570 void __attribute__((weak)) mach_reboot_fixups(void)
575 * To the best of our knowledge Windows compatible x86 hardware expects
576 * the following on reboot:
578 * 1) If the FADT has the ACPI reboot register flag set, try it
579 * 2) If still alive, write to the keyboard controller
580 * 3) If still alive, write to the ACPI reboot register again
581 * 4) If still alive, write to the keyboard controller again
582 * 5) If still alive, call the EFI runtime service to reboot
583 * 6) If no EFI runtime service, call the BIOS to do a reboot
585 * We default to following the same pattern. We also have
586 * two other reboot methods: 'triple fault' and 'PCI', which
587 * can be triggered via the reboot= kernel boot option or
590 * This means that this function can never return, it can misbehave
591 * by not rebooting properly and hanging.
593 static void native_machine_emergency_restart(void)
597 int orig_reboot_type = reboot_type;
600 if (reboot_emergency)
601 emergency_vmx_disable_all();
603 tboot_shutdown(TB_SHUTDOWN_REBOOT);
605 /* Tell the BIOS if we want cold or warm reboot */
606 mode = reboot_mode == REBOOT_WARM ? 0x1234 : 0;
607 *((unsigned short *)__va(0x472)) = mode;
610 * If an EFI capsule has been registered with the firmware then
611 * override the reboot= parameter.
613 if (efi_capsule_pending(NULL)) {
614 pr_info("EFI capsule is pending, forcing EFI reboot.\n");
615 reboot_type = BOOT_EFI;
619 /* Could also try the reset bit in the Hammer NB */
620 switch (reboot_type) {
623 reboot_type = BOOT_KBD;
627 mach_reboot_fixups(); /* For board specific fixups */
629 for (i = 0; i < 10; i++) {
632 outb(0xfe, 0x64); /* Pulse reset low */
635 if (attempt == 0 && orig_reboot_type == BOOT_ACPI) {
637 reboot_type = BOOT_ACPI;
639 reboot_type = BOOT_EFI;
644 efi_reboot(reboot_mode, NULL);
645 reboot_type = BOOT_BIOS;
649 machine_real_restart(MRR_BIOS);
651 /* We're probably dead after this, but... */
652 reboot_type = BOOT_CF9_SAFE;
656 port_cf9_safe = true;
661 u8 reboot_code = reboot_mode == REBOOT_WARM ? 0x06 : 0x0E;
662 u8 cf9 = inb(0xcf9) & ~reboot_code;
663 outb(cf9|2, 0xcf9); /* Request hard reset */
665 /* Actually do the reset */
666 outb(cf9|reboot_code, 0xcf9);
669 reboot_type = BOOT_TRIPLE;
674 __asm__ __volatile__("int3");
676 /* We're probably dead after this, but... */
677 reboot_type = BOOT_KBD;
683 void native_machine_shutdown(void)
685 /* Stop the cpus and apics */
686 #ifdef CONFIG_X86_IO_APIC
688 * Disabling IO APIC before local APIC is a workaround for
689 * erratum AVR31 in "Intel Atom Processor C2000 Product Family
690 * Specification Update". In this situation, interrupts that target
691 * a Logical Processor whose Local APIC is either in the process of
692 * being hardware disabled or software disabled are neither delivered
693 * nor discarded. When this erratum occurs, the processor may hang.
695 * Even without the erratum, it still makes sense to quiet IO APIC
696 * before disabling Local APIC.
703 * Stop all of the others. Also disable the local irq to
704 * not receive the per-cpu timer interrupt which may trigger
705 * scheduler's load balance.
712 restore_boot_irq_mode();
714 #ifdef CONFIG_HPET_TIMER
719 x86_platform.iommu_shutdown();
723 static void __machine_emergency_restart(int emergency)
725 reboot_emergency = emergency;
726 machine_ops.emergency_restart();
729 static void native_machine_restart(char *__unused)
731 pr_notice("machine restart\n");
735 __machine_emergency_restart(0);
738 static void native_machine_halt(void)
740 /* Stop other cpus and apics */
743 tboot_shutdown(TB_SHUTDOWN_HALT);
748 static void native_machine_power_off(void)
755 /* A fallback in case there is no PM info available */
756 tboot_shutdown(TB_SHUTDOWN_HALT);
759 struct machine_ops machine_ops __ro_after_init = {
760 .power_off = native_machine_power_off,
761 .shutdown = native_machine_shutdown,
762 .emergency_restart = native_machine_emergency_restart,
763 .restart = native_machine_restart,
764 .halt = native_machine_halt,
765 #ifdef CONFIG_KEXEC_CORE
766 .crash_shutdown = native_machine_crash_shutdown,
770 void machine_power_off(void)
772 machine_ops.power_off();
775 void machine_shutdown(void)
777 machine_ops.shutdown();
780 void machine_emergency_restart(void)
782 __machine_emergency_restart(1);
785 void machine_restart(char *cmd)
787 machine_ops.restart(cmd);
790 void machine_halt(void)
795 #ifdef CONFIG_KEXEC_CORE
796 void machine_crash_shutdown(struct pt_regs *regs)
798 machine_ops.crash_shutdown(regs);
803 /* This is the CPU performing the emergency shutdown work. */
804 int crashing_cpu = -1;
806 #if defined(CONFIG_SMP)
808 static nmi_shootdown_cb shootdown_callback;
810 static atomic_t waiting_for_crash_ipi;
811 static int crash_ipi_issued;
813 static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
817 cpu = raw_smp_processor_id();
820 * Don't do anything if this handler is invoked on crashing cpu.
821 * Otherwise, system will completely hang. Crashing cpu can get
822 * an NMI if system was initially booted with nmi_watchdog parameter.
824 if (cpu == crashing_cpu)
828 shootdown_callback(cpu, regs);
830 atomic_dec(&waiting_for_crash_ipi);
831 /* Assume hlt works */
840 * Halt all other CPUs, calling the specified function on each of them
842 * This function can be used to halt all other CPUs on crash
843 * or emergency reboot time. The function passed as parameter
844 * will be called inside a NMI handler on all CPUs.
846 void nmi_shootdown_cpus(nmi_shootdown_cb callback)
851 /* Make a note of crashing cpu. Will be used in NMI callback. */
852 crashing_cpu = safe_smp_processor_id();
854 shootdown_callback = callback;
856 atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
857 /* Would it be better to replace the trap vector here? */
858 if (register_nmi_handler(NMI_LOCAL, crash_nmi_callback,
859 NMI_FLAG_FIRST, "crash"))
860 return; /* Return what? */
862 * Ensure the new callback function is set before sending
867 apic_send_IPI_allbutself(NMI_VECTOR);
869 /* Kick CPUs looping in NMI context. */
870 WRITE_ONCE(crash_ipi_issued, 1);
872 msecs = 1000; /* Wait at most a second for the other cpus to stop */
873 while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
878 /* Leave the nmi callback set */
882 * Check if the crash dumping IPI got issued and if so, call its callback
883 * directly. This function is used when we have already been in NMI handler.
886 void run_crash_ipi_callback(struct pt_regs *regs)
888 if (crash_ipi_issued)
889 crash_nmi_callback(0, regs);
892 /* Override the weak function in kernel/panic.c */
893 void nmi_panic_self_stop(struct pt_regs *regs)
896 /* If no CPU is preparing crash dump, we simply loop here. */
897 run_crash_ipi_callback(regs);
902 #else /* !CONFIG_SMP */
903 void nmi_shootdown_cpus(nmi_shootdown_cb callback)
905 /* No other CPUs to shoot down */
908 void run_crash_ipi_callback(struct pt_regs *regs)