// SPDX-License-Identifier: GPL-2.0 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Power off function, if any */ void (*pm_power_off)(void); EXPORT_SYMBOL(pm_power_off); /* * This is set if we need to go through the 'emergency' path. * When machine_emergency_restart() is called, we may be on * an inconsistent state and won't be able to do a clean cleanup */ static int reboot_emergency; /* This is set by the PCI code if either type 1 or type 2 PCI is detected */ bool port_cf9_safe = false; /* * Reboot options and system auto-detection code provided by * Dell Inc. so their systems "just work". :-) */ /* * Some machines require the "reboot=a" commandline options */ static int __init set_acpi_reboot(const struct dmi_system_id *d) { if (reboot_type != BOOT_ACPI) { reboot_type = BOOT_ACPI; pr_info("%s series board detected. Selecting %s-method for reboots.\n", d->ident, "ACPI"); } return 0; } /* * Some machines require the "reboot=b" or "reboot=k" commandline options, * this quirk makes that automatic. */ static int __init set_bios_reboot(const struct dmi_system_id *d) { if (reboot_type != BOOT_BIOS) { reboot_type = BOOT_BIOS; pr_info("%s series board detected. Selecting %s-method for reboots.\n", d->ident, "BIOS"); } return 0; } /* * Some machines don't handle the default ACPI reboot method and * require the EFI reboot method: */ static int __init set_efi_reboot(const struct dmi_system_id *d) { if (reboot_type != BOOT_EFI && !efi_runtime_disabled()) { reboot_type = BOOT_EFI; pr_info("%s series board detected. Selecting EFI-method for reboot.\n", d->ident); } return 0; } void __noreturn machine_real_restart(unsigned int type) { local_irq_disable(); /* * Write zero to CMOS register number 0x0f, which the BIOS POST * routine will recognize as telling it to do a proper reboot. (Well * that's what this book in front of me says -- it may only apply to * the Phoenix BIOS though, it's not clear). At the same time, * disable NMIs by setting the top bit in the CMOS address register, * as we're about to do peculiar things to the CPU. I'm not sure if * `outb_p' is needed instead of just `outb'. Use it to be on the * safe side. (Yes, CMOS_WRITE does outb_p's. - Paul G.) */ spin_lock(&rtc_lock); CMOS_WRITE(0x00, 0x8f); spin_unlock(&rtc_lock); /* * Switch to the trampoline page table. */ load_trampoline_pgtable(); /* Jump to the identity-mapped low memory code */ #ifdef CONFIG_X86_32 asm volatile("jmpl *%0" : : "rm" (real_mode_header->machine_real_restart_asm), "a" (type)); #else asm volatile("ljmpl *%0" : : "m" (real_mode_header->machine_real_restart_asm), "D" (type)); #endif unreachable(); } #ifdef CONFIG_APM_MODULE EXPORT_SYMBOL(machine_real_restart); #endif STACK_FRAME_NON_STANDARD(machine_real_restart); /* * Some Apple MacBook and MacBookPro's needs reboot=p to be able to reboot */ static int __init set_pci_reboot(const struct dmi_system_id *d) { if (reboot_type != BOOT_CF9_FORCE) { reboot_type = BOOT_CF9_FORCE; pr_info("%s series board detected. Selecting %s-method for reboots.\n", d->ident, "PCI"); } return 0; } static int __init set_kbd_reboot(const struct dmi_system_id *d) { if (reboot_type != BOOT_KBD) { reboot_type = BOOT_KBD; pr_info("%s series board detected. Selecting %s-method for reboot.\n", d->ident, "KBD"); } return 0; } /* * This is a single dmi_table handling all reboot quirks. */ static const struct dmi_system_id reboot_dmi_table[] __initconst = { /* Acer */ { /* Handle reboot issue on Acer Aspire one */ .callback = set_kbd_reboot, .ident = "Acer Aspire One A110", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Acer"), DMI_MATCH(DMI_PRODUCT_NAME, "AOA110"), }, }, { /* Handle reboot issue on Acer TravelMate X514-51T */ .callback = set_efi_reboot, .ident = "Acer TravelMate X514-51T", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Acer"), DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate X514-51T"), }, }, /* Apple */ { /* Handle problems with rebooting on Apple MacBook5 */ .callback = set_pci_reboot, .ident = "Apple MacBook5", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "MacBook5"), }, }, { /* Handle problems with rebooting on Apple MacBook6,1 */ .callback = set_pci_reboot, .ident = "Apple MacBook6,1", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "MacBook6,1"), }, }, { /* Handle problems with rebooting on Apple MacBookPro5 */ .callback = set_pci_reboot, .ident = "Apple MacBookPro5", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro5"), }, }, { /* Handle problems with rebooting on Apple Macmini3,1 */ .callback = set_pci_reboot, .ident = "Apple Macmini3,1", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Macmini3,1"), }, }, { /* Handle problems with rebooting on the iMac9,1. */ .callback = set_pci_reboot, .ident = "Apple iMac9,1", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "iMac9,1"), }, }, { /* Handle problems with rebooting on the iMac10,1. */ .callback = set_pci_reboot, .ident = "Apple iMac10,1", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "iMac10,1"), }, }, /* ASRock */ { /* Handle problems with rebooting on ASRock Q1900DC-ITX */ .callback = set_pci_reboot, .ident = "ASRock Q1900DC-ITX", .matches = { DMI_MATCH(DMI_BOARD_VENDOR, "ASRock"), DMI_MATCH(DMI_BOARD_NAME, "Q1900DC-ITX"), }, }, /* ASUS */ { /* Handle problems with rebooting on ASUS P4S800 */ .callback = set_bios_reboot, .ident = "ASUS P4S800", .matches = { DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer INC."), DMI_MATCH(DMI_BOARD_NAME, "P4S800"), }, }, { /* Handle problems with rebooting on ASUS EeeBook X205TA */ .callback = set_acpi_reboot, .ident = "ASUS EeeBook X205TA", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."), DMI_MATCH(DMI_PRODUCT_NAME, "X205TA"), }, }, { /* Handle problems with rebooting on ASUS EeeBook X205TAW */ .callback = set_acpi_reboot, .ident = "ASUS EeeBook X205TAW", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."), DMI_MATCH(DMI_PRODUCT_NAME, "X205TAW"), }, }, /* Certec */ { /* Handle problems with rebooting on Certec BPC600 */ .callback = set_pci_reboot, .ident = "Certec BPC600", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Certec"), DMI_MATCH(DMI_PRODUCT_NAME, "BPC600"), }, }, /* Dell */ { /* Handle problems with rebooting on Dell DXP061 */ .callback = set_bios_reboot, .ident = "Dell DXP061", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Dell DXP061"), }, }, { /* Handle problems with rebooting on Dell E520's */ .callback = set_bios_reboot, .ident = "Dell E520", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Dell DM061"), }, }, { /* Handle problems with rebooting on the Latitude E5410. */ .callback = set_pci_reboot, .ident = "Dell Latitude E5410", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5410"), }, }, { /* Handle problems with rebooting on the Latitude E5420. */ .callback = set_pci_reboot, .ident = "Dell Latitude E5420", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E5420"), }, }, { /* Handle problems with rebooting on the Latitude E6320. */ .callback = set_pci_reboot, .ident = "Dell Latitude E6320", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6320"), }, }, { /* Handle problems with rebooting on the Latitude E6420. */ .callback = set_pci_reboot, .ident = "Dell Latitude E6420", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Latitude E6420"), }, }, { /* Handle problems with rebooting on Dell Optiplex 330 with 0KP561 */ .callback = set_bios_reboot, .ident = "Dell OptiPlex 330", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 330"), DMI_MATCH(DMI_BOARD_NAME, "0KP561"), }, }, { /* Handle problems with rebooting on Dell Optiplex 360 with 0T656F */ .callback = set_bios_reboot, .ident = "Dell OptiPlex 360", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 360"), DMI_MATCH(DMI_BOARD_NAME, "0T656F"), }, }, { /* Handle problems with rebooting on Dell Optiplex 745's SFF */ .callback = set_bios_reboot, .ident = "Dell OptiPlex 745", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"), }, }, { /* Handle problems with rebooting on Dell Optiplex 745's DFF */ .callback = set_bios_reboot, .ident = "Dell OptiPlex 745", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"), DMI_MATCH(DMI_BOARD_NAME, "0MM599"), }, }, { /* Handle problems with rebooting on Dell Optiplex 745 with 0KW626 */ .callback = set_bios_reboot, .ident = "Dell OptiPlex 745", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 745"), DMI_MATCH(DMI_BOARD_NAME, "0KW626"), }, }, { /* Handle problems with rebooting on Dell OptiPlex 760 with 0G919G */ .callback = set_bios_reboot, .ident = "Dell OptiPlex 760", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 760"), DMI_MATCH(DMI_BOARD_NAME, "0G919G"), }, }, { /* Handle problems with rebooting on the OptiPlex 990. */ .callback = set_pci_reboot, .ident = "Dell OptiPlex 990 BIOS A0x", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 990"), DMI_MATCH(DMI_BIOS_VERSION, "A0"), }, }, { /* Handle problems with rebooting on Dell 300's */ .callback = set_bios_reboot, .ident = "Dell PowerEdge 300", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"), DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 300/"), }, }, { /* Handle problems with rebooting on Dell 1300's */ .callback = set_bios_reboot, .ident = "Dell PowerEdge 1300", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"), DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 1300/"), }, }, { /* Handle problems with rebooting on Dell 2400's */ .callback = set_bios_reboot, .ident = "Dell PowerEdge 2400", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"), DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 2400"), }, }, { /* Handle problems with rebooting on the Dell PowerEdge C6100. */ .callback = set_pci_reboot, .ident = "Dell PowerEdge C6100", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell"), DMI_MATCH(DMI_PRODUCT_NAME, "C6100"), }, }, { /* Handle problems with rebooting on the Precision M6600. */ .callback = set_pci_reboot, .ident = "Dell Precision M6600", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Precision M6600"), }, }, { /* Handle problems with rebooting on Dell T5400's */ .callback = set_bios_reboot, .ident = "Dell Precision T5400", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T5400"), }, }, { /* Handle problems with rebooting on Dell T7400's */ .callback = set_bios_reboot, .ident = "Dell Precision T7400", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Precision WorkStation T7400"), }, }, { /* Handle problems with rebooting on Dell XPS710 */ .callback = set_bios_reboot, .ident = "Dell XPS710", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "Dell XPS710"), }, }, { /* Handle problems with rebooting on Dell Optiplex 7450 AIO */ .callback = set_acpi_reboot, .ident = "Dell OptiPlex 7450 AIO", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 7450 AIO"), }, }, /* Hewlett-Packard */ { /* Handle problems with rebooting on HP laptops */ .callback = set_bios_reboot, .ident = "HP Compaq Laptop", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"), DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq"), }, }, { /* PCIe Wifi card isn't detected after reboot otherwise */ .callback = set_pci_reboot, .ident = "Zotac ZBOX CI327 nano", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "NA"), DMI_MATCH(DMI_PRODUCT_NAME, "ZBOX-CI327NANO-GS-01"), }, }, /* Sony */ { /* Handle problems with rebooting on Sony VGN-Z540N */ .callback = set_bios_reboot, .ident = "Sony VGN-Z540N", .matches = { DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"), DMI_MATCH(DMI_PRODUCT_NAME, "VGN-Z540N"), }, }, { } }; static int __init reboot_init(void) { int rv; /* * Only do the DMI check if reboot_type hasn't been overridden * on the command line */ if (!reboot_default) return 0; /* * The DMI quirks table takes precedence. If no quirks entry * matches and the ACPI Hardware Reduced bit is set and EFI * runtime services are enabled, force EFI reboot. */ rv = dmi_check_system(reboot_dmi_table); if (!rv && efi_reboot_required() && !efi_runtime_disabled()) reboot_type = BOOT_EFI; return 0; } core_initcall(reboot_init); static inline void kb_wait(void) { int i; for (i = 0; i < 0x10000; i++) { if ((inb(0x64) & 0x02) == 0) break; udelay(2); } } static inline void nmi_shootdown_cpus_on_restart(void); static void emergency_reboot_disable_virtualization(void) { /* Just make sure we won't change CPUs while doing this */ local_irq_disable(); /* * Disable virtualization on all CPUs before rebooting to avoid hanging * the system, as VMX and SVM block INIT when running in the host. * * We can't take any locks and we may be on an inconsistent state, so * use NMIs as IPIs to tell the other CPUs to disable VMX/SVM and halt. * * Do the NMI shootdown even if virtualization is off on _this_ CPU, as * other CPUs may have virtualization enabled. */ if (cpu_has_vmx() || cpu_has_svm(NULL)) { /* Safely force _this_ CPU out of VMX/SVM operation. */ cpu_emergency_disable_virtualization(); /* Disable VMX/SVM and halt on other CPUs. */ nmi_shootdown_cpus_on_restart(); } } void __attribute__((weak)) mach_reboot_fixups(void) { } /* * To the best of our knowledge Windows compatible x86 hardware expects * the following on reboot: * * 1) If the FADT has the ACPI reboot register flag set, try it * 2) If still alive, write to the keyboard controller * 3) If still alive, write to the ACPI reboot register again * 4) If still alive, write to the keyboard controller again * 5) If still alive, call the EFI runtime service to reboot * 6) If no EFI runtime service, call the BIOS to do a reboot * * We default to following the same pattern. We also have * two other reboot methods: 'triple fault' and 'PCI', which * can be triggered via the reboot= kernel boot option or * via quirks. * * This means that this function can never return, it can misbehave * by not rebooting properly and hanging. */ static void native_machine_emergency_restart(void) { int i; int attempt = 0; int orig_reboot_type = reboot_type; unsigned short mode; if (reboot_emergency) emergency_reboot_disable_virtualization(); tboot_shutdown(TB_SHUTDOWN_REBOOT); /* Tell the BIOS if we want cold or warm reboot */ mode = reboot_mode == REBOOT_WARM ? 0x1234 : 0; *((unsigned short *)__va(0x472)) = mode; /* * If an EFI capsule has been registered with the firmware then * override the reboot= parameter. */ if (efi_capsule_pending(NULL)) { pr_info("EFI capsule is pending, forcing EFI reboot.\n"); reboot_type = BOOT_EFI; } for (;;) { /* Could also try the reset bit in the Hammer NB */ switch (reboot_type) { case BOOT_ACPI: acpi_reboot(); reboot_type = BOOT_KBD; break; case BOOT_KBD: mach_reboot_fixups(); /* For board specific fixups */ for (i = 0; i < 10; i++) { kb_wait(); udelay(50); outb(0xfe, 0x64); /* Pulse reset low */ udelay(50); } if (attempt == 0 && orig_reboot_type == BOOT_ACPI) { attempt = 1; reboot_type = BOOT_ACPI; } else { reboot_type = BOOT_EFI; } break; case BOOT_EFI: efi_reboot(reboot_mode, NULL); reboot_type = BOOT_BIOS; break; case BOOT_BIOS: machine_real_restart(MRR_BIOS); /* We're probably dead after this, but... */ reboot_type = BOOT_CF9_SAFE; break; case BOOT_CF9_FORCE: port_cf9_safe = true; fallthrough; case BOOT_CF9_SAFE: if (port_cf9_safe) { u8 reboot_code = reboot_mode == REBOOT_WARM ? 0x06 : 0x0E; u8 cf9 = inb(0xcf9) & ~reboot_code; outb(cf9|2, 0xcf9); /* Request hard reset */ udelay(50); /* Actually do the reset */ outb(cf9|reboot_code, 0xcf9); udelay(50); } reboot_type = BOOT_TRIPLE; break; case BOOT_TRIPLE: idt_invalidate(); __asm__ __volatile__("int3"); /* We're probably dead after this, but... */ reboot_type = BOOT_KBD; break; } } } void native_machine_shutdown(void) { /* Stop the cpus and apics */ #ifdef CONFIG_X86_IO_APIC /* * Disabling IO APIC before local APIC is a workaround for * erratum AVR31 in "Intel Atom Processor C2000 Product Family * Specification Update". In this situation, interrupts that target * a Logical Processor whose Local APIC is either in the process of * being hardware disabled or software disabled are neither delivered * nor discarded. When this erratum occurs, the processor may hang. * * Even without the erratum, it still makes sense to quiet IO APIC * before disabling Local APIC. */ clear_IO_APIC(); #endif #ifdef CONFIG_SMP /* * Stop all of the others. Also disable the local irq to * not receive the per-cpu timer interrupt which may trigger * scheduler's load balance. */ local_irq_disable(); stop_other_cpus(); #endif lapic_shutdown(); restore_boot_irq_mode(); #ifdef CONFIG_HPET_TIMER hpet_disable(); #endif #ifdef CONFIG_X86_64 x86_platform.iommu_shutdown(); #endif } static void __machine_emergency_restart(int emergency) { reboot_emergency = emergency; machine_ops.emergency_restart(); } static void native_machine_restart(char *__unused) { pr_notice("machine restart\n"); if (!reboot_force) machine_shutdown(); __machine_emergency_restart(0); } static void native_machine_halt(void) { /* Stop other cpus and apics */ machine_shutdown(); tboot_shutdown(TB_SHUTDOWN_HALT); stop_this_cpu(NULL); } static void native_machine_power_off(void) { if (pm_power_off) { if (!reboot_force) machine_shutdown(); pm_power_off(); } /* A fallback in case there is no PM info available */ tboot_shutdown(TB_SHUTDOWN_HALT); } struct machine_ops machine_ops __ro_after_init = { .power_off = native_machine_power_off, .shutdown = native_machine_shutdown, .emergency_restart = native_machine_emergency_restart, .restart = native_machine_restart, .halt = native_machine_halt, #ifdef CONFIG_KEXEC_CORE .crash_shutdown = native_machine_crash_shutdown, #endif }; void machine_power_off(void) { machine_ops.power_off(); } void machine_shutdown(void) { machine_ops.shutdown(); } void machine_emergency_restart(void) { __machine_emergency_restart(1); } void machine_restart(char *cmd) { machine_ops.restart(cmd); } void machine_halt(void) { machine_ops.halt(); } #ifdef CONFIG_KEXEC_CORE void machine_crash_shutdown(struct pt_regs *regs) { machine_ops.crash_shutdown(regs); } #endif /* This is the CPU performing the emergency shutdown work. */ int crashing_cpu = -1; /* * Disable virtualization, i.e. VMX or SVM, to ensure INIT is recognized during * reboot. VMX blocks INIT if the CPU is post-VMXON, and SVM blocks INIT if * GIF=0, i.e. if the crash occurred between CLGI and STGI. */ void cpu_emergency_disable_virtualization(void) { cpu_emergency_vmxoff(); cpu_emergency_svm_disable(); } #if defined(CONFIG_SMP) static nmi_shootdown_cb shootdown_callback; static atomic_t waiting_for_crash_ipi; static int crash_ipi_issued; static int crash_nmi_callback(unsigned int val, struct pt_regs *regs) { int cpu; cpu = raw_smp_processor_id(); /* * Don't do anything if this handler is invoked on crashing cpu. * Otherwise, system will completely hang. Crashing cpu can get * an NMI if system was initially booted with nmi_watchdog parameter. */ if (cpu == crashing_cpu) return NMI_HANDLED; local_irq_disable(); if (shootdown_callback) shootdown_callback(cpu, regs); /* * Prepare the CPU for reboot _after_ invoking the callback so that the * callback can safely use virtualization instructions, e.g. VMCLEAR. */ cpu_emergency_disable_virtualization(); atomic_dec(&waiting_for_crash_ipi); /* Assume hlt works */ halt(); for (;;) cpu_relax(); return NMI_HANDLED; } /** * nmi_shootdown_cpus - Stop other CPUs via NMI * @callback: Optional callback to be invoked from the NMI handler * * The NMI handler on the remote CPUs invokes @callback, if not * NULL, first and then disables virtualization to ensure that * INIT is recognized during reboot. * * nmi_shootdown_cpus() can only be invoked once. After the first * invocation all other CPUs are stuck in crash_nmi_callback() and * cannot respond to a second NMI. */ void nmi_shootdown_cpus(nmi_shootdown_cb callback) { unsigned long msecs; local_irq_disable(); /* * Avoid certain doom if a shootdown already occurred; re-registering * the NMI handler will cause list corruption, modifying the callback * will do who knows what, etc... */ if (WARN_ON_ONCE(crash_ipi_issued)) return; /* Make a note of crashing cpu. Will be used in NMI callback. */ crashing_cpu = safe_smp_processor_id(); shootdown_callback = callback; atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); /* Would it be better to replace the trap vector here? */ if (register_nmi_handler(NMI_LOCAL, crash_nmi_callback, NMI_FLAG_FIRST, "crash")) return; /* Return what? */ /* * Ensure the new callback function is set before sending * out the NMI */ wmb(); apic_send_IPI_allbutself(NMI_VECTOR); /* Kick CPUs looping in NMI context. */ WRITE_ONCE(crash_ipi_issued, 1); msecs = 1000; /* Wait at most a second for the other cpus to stop */ while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { mdelay(1); msecs--; } /* * Leave the nmi callback set, shootdown is a one-time thing. Clearing * the callback could result in a NULL pointer dereference if a CPU * (finally) responds after the timeout expires. */ } static inline void nmi_shootdown_cpus_on_restart(void) { if (!crash_ipi_issued) nmi_shootdown_cpus(NULL); } /* * Check if the crash dumping IPI got issued and if so, call its callback * directly. This function is used when we have already been in NMI handler. * It doesn't return. */ void run_crash_ipi_callback(struct pt_regs *regs) { if (crash_ipi_issued) crash_nmi_callback(0, regs); } /* Override the weak function in kernel/panic.c */ void nmi_panic_self_stop(struct pt_regs *regs) { while (1) { /* If no CPU is preparing crash dump, we simply loop here. */ run_crash_ipi_callback(regs); cpu_relax(); } } #else /* !CONFIG_SMP */ void nmi_shootdown_cpus(nmi_shootdown_cb callback) { /* No other CPUs to shoot down */ } static inline void nmi_shootdown_cpus_on_restart(void) { } void run_crash_ipi_callback(struct pt_regs *regs) { } #endif