#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/pm.h>
#include <linux/efi.h>
#include <linux/dmi.h>
#include <linux/sched.h>
#include <linux/tboot.h>
#include <linux/delay.h>
#include <acpi/reboot.h>
#include <asm/io.h>
#include <asm/apic.h>
#include <asm/io_apic.h>
#include <asm/desc.h>
#include <asm/hpet.h>
#include <asm/pgtable.h>
#include <asm/proto.h>
#include <asm/reboot_fixups.h>
#include <asm/reboot.h>
#include <asm/pci_x86.h>
#include <asm/virtext.h>
#include <asm/cpu.h>
#include <asm/nmi.h>
#include <asm/smp.h>

#include <linux/ctype.h>
#include <linux/mc146818rtc.h>
#include <asm/realmode.h>
#include <asm/x86_init.h>
#include <asm/efi.h>

/*
 * Power off function, if any
 */
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

static const struct desc_ptr no_idt = {};

/*
 * 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=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;
}

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 back to the initial page table.
         */
#ifdef CONFIG_X86_32
        load_cr3(initial_page_table);
#else
        write_cr3(real_mode_header->trampoline_pgd);
#endif

        /* 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

/*
 * 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 struct dmi_system_id __initdata reboot_dmi_table[] = {

        /* 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"),
                },
        },

        /* 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 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"),
                },
        },

        /* 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",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
                        DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 990"),
                },
        },
        {       /* 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"),
                },
        },

        /* 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"),
                },
        },

        /* 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, force EFI
         * reboot.
         */
        rv = dmi_check_system(reboot_dmi_table);

        if (!rv && efi_reboot_required())
                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 void vmxoff_nmi(int cpu, struct pt_regs *regs)
{
        cpu_emergency_vmxoff();
}

/* Use NMIs as IPIs to tell all CPUs to disable virtualization */
static void emergency_vmx_disable_all(void)
{
        /* Just make sure we won't change CPUs while doing this */
        local_irq_disable();

        /*
         * We need to disable VMX on all CPUs before rebooting, otherwise
         * we risk hanging up the machine, because the CPU ignore INIT
         * signals when VMX is enabled.
         *
         * We can't take any locks and we may be on an inconsistent
         * state, so we use NMIs as IPIs to tell the other CPUs to disable
         * VMX and halt.
         *
         * For safety, we will avoid running the nmi_shootdown_cpus()
         * stuff unnecessarily, but we don't have a way to check
         * if other CPUs have VMX enabled. So we will call it only if the
         * CPU we are running on has VMX enabled.
         *
         * We will miss cases where VMX is not enabled on all CPUs. This
         * shouldn't do much harm because KVM always enable VMX on all
         * CPUs anyway. But we can miss it on the small window where KVM
         * is still enabling VMX.
         */
        if (cpu_has_vmx() && cpu_vmx_enabled()) {
                /* Disable VMX on this CPU. */
                cpu_vmxoff();

                /* Halt and disable VMX on the other CPUs */
                nmi_shootdown_cpus(vmxoff_nmi);

        }
}


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_vmx_disable_all();

        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;

        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;
                        /* Fall through */

                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:
                        load_idt(&no_idt);
                        __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.
         */
        disable_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();

#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 = {
        .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


#if defined(CONFIG_SMP)

/* This keeps a track of which one is crashing cpu. */
static int crashing_cpu;
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();

        shootdown_callback(cpu, regs);

        atomic_dec(&waiting_for_crash_ipi);
        /* Assume hlt works */
        halt();
        for (;;)
                cpu_relax();

        return NMI_HANDLED;
}

static void smp_send_nmi_allbutself(void)
{
        apic->send_IPI_allbutself(NMI_VECTOR);
}

/*
 * Halt all other CPUs, calling the specified function on each of them
 *
 * This function can be used to halt all other CPUs on crash
 * or emergency reboot time. The function passed as parameter
 * will be called inside a NMI handler on all CPUs.
 */
void nmi_shootdown_cpus(nmi_shootdown_cb callback)
{
        unsigned long msecs;
        local_irq_disable();

        /* 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();

        smp_send_nmi_allbutself();

        /* 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 */
}

/*
 * 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 */
}

void run_crash_ipi_callback(struct pt_regs *regs)
{
}
#endif