// SPDX-License-Identifier: GPL-2.0-only
/*
 * machine_kexec.c for kexec
 *
 * Copyright (C) 2022 Loongson Technology Corporation Limited
 */
#include <linux/compiler.h>
#include <linux/cpu.h>
#include <linux/kexec.h>
#include <linux/crash_dump.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/libfdt.h>
#include <linux/mm.h>
#include <linux/of_fdt.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>

#include <asm/bootinfo.h>
#include <asm/cacheflush.h>
#include <asm/page.h>

/* 0x100000 ~ 0x200000 is safe */
#define KEXEC_CONTROL_CODE      TO_CACHE(0x100000UL)
#define KEXEC_CMDLINE_ADDR      TO_CACHE(0x108000UL)

static unsigned long reboot_code_buffer;
static cpumask_t cpus_in_crash = CPU_MASK_NONE;

#ifdef CONFIG_SMP
static void (*relocated_kexec_smp_wait)(void *);
atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
#endif

static unsigned long efi_boot;
static unsigned long cmdline_ptr;
static unsigned long systable_ptr;
static unsigned long start_addr;
static unsigned long first_ind_entry;

int machine_kexec_prepare(struct kimage *kimage)
{
        int i;
        char *bootloader = "kexec";
        void *cmdline_ptr = (void *)KEXEC_CMDLINE_ADDR;

        kimage->arch.efi_boot = fw_arg0;
        kimage->arch.systable_ptr = fw_arg2;

        if (kimage->file_mode == 1) {
                /*
                 * kimage->cmdline_buf will be released in kexec_file_load, so copy
                 * to the KEXEC_CMDLINE_ADDR safe area.
                 */
                memcpy((void *)KEXEC_CMDLINE_ADDR, (void *)kimage->arch.cmdline_ptr,
                                        strlen((char *)kimage->arch.cmdline_ptr) + 1);
                kimage->arch.cmdline_ptr = (unsigned long)KEXEC_CMDLINE_ADDR;
        } else {
                /* Find the command line */
                for (i = 0; i < kimage->nr_segments; i++) {
                        if (!strncmp(bootloader, (char __user *)kimage->segment[i].buf, strlen(bootloader))) {
                                if (!copy_from_user(cmdline_ptr, kimage->segment[i].buf, COMMAND_LINE_SIZE))
                                        kimage->arch.cmdline_ptr = (unsigned long)cmdline_ptr;
                                break;
                        }
                }

                if (!kimage->arch.cmdline_ptr) {
                        pr_err("Command line not included in the provided image\n");
                        return -EINVAL;
                }
        }

        /* kexec/kdump need a safe page to save reboot_code_buffer */
        kimage->control_code_page = virt_to_page((void *)KEXEC_CONTROL_CODE);

        reboot_code_buffer = (unsigned long)page_address(kimage->control_code_page);
        memcpy((void *)reboot_code_buffer, relocate_new_kernel, relocate_new_kernel_size);

#ifdef CONFIG_SMP
        /* All secondary cpus now may jump to kexec_smp_wait cycle */
        relocated_kexec_smp_wait = reboot_code_buffer + (void *)(kexec_smp_wait - relocate_new_kernel);
#endif

        return 0;
}

void machine_kexec_cleanup(struct kimage *kimage)
{
}

void kexec_reboot(void)
{
        do_kexec_t do_kexec = NULL;

        /*
         * We know we were online, and there will be no incoming IPIs at
         * this point. Mark online again before rebooting so that the crash
         * analysis tool will see us correctly.
         */
        set_cpu_online(smp_processor_id(), true);

        /* Ensure remote CPUs observe that we're online before rebooting. */
        smp_mb__after_atomic();

        /*
         * Make sure we get correct instructions written by the
         * machine_kexec_prepare() CPU.
         */
        __asm__ __volatile__ ("\tibar 0\n"::);

#ifdef CONFIG_SMP
        /* All secondary cpus go to kexec_smp_wait */
        if (smp_processor_id() > 0) {
                relocated_kexec_smp_wait(NULL);
                BUG();
        }
#endif

        do_kexec = (void *)reboot_code_buffer;
        do_kexec(efi_boot, cmdline_ptr, systable_ptr, start_addr, first_ind_entry);

        BUG();
}


#ifdef CONFIG_SMP
static void kexec_shutdown_secondary(void *regs)
{
        int cpu = smp_processor_id();

        if (!cpu_online(cpu))
                return;

        /* We won't be sent IPIs any more. */
        set_cpu_online(cpu, false);

        local_irq_disable();
        while (!atomic_read(&kexec_ready_to_reboot))
                cpu_relax();

        kexec_reboot();
}

static void crash_shutdown_secondary(void *passed_regs)
{
        int cpu = smp_processor_id();
        struct pt_regs *regs = passed_regs;

        /*
         * If we are passed registers, use those. Otherwise get the
         * regs from the last interrupt, which should be correct, as
         * we are in an interrupt. But if the regs are not there,
         * pull them from the top of the stack. They are probably
         * wrong, but we need something to keep from crashing again.
         */
        if (!regs)
                regs = get_irq_regs();
        if (!regs)
                regs = task_pt_regs(current);

        if (!cpu_online(cpu))
                return;

        /* We won't be sent IPIs any more. */
        set_cpu_online(cpu, false);

        local_irq_disable();
        if (!cpumask_test_cpu(cpu, &cpus_in_crash))
                crash_save_cpu(regs, cpu);
        cpumask_set_cpu(cpu, &cpus_in_crash);

        while (!atomic_read(&kexec_ready_to_reboot))
                cpu_relax();

        kexec_reboot();
}

void crash_smp_send_stop(void)
{
        unsigned int ncpus;
        unsigned long timeout;
        static int cpus_stopped;

        /*
         * This function can be called twice in panic path, but obviously
         * we should execute this only once.
         */
        if (cpus_stopped)
                return;

        cpus_stopped = 1;

         /* Excluding the panic cpu */
        ncpus = num_online_cpus() - 1;

        smp_call_function(crash_shutdown_secondary, NULL, 0);
        smp_wmb();

        /*
         * The crash CPU sends an IPI and wait for other CPUs to
         * respond. Delay of at least 10 seconds.
         */
        timeout = MSEC_PER_SEC * 10;
        pr_emerg("Sending IPI to other cpus...\n");
        while ((cpumask_weight(&cpus_in_crash) < ncpus) && timeout--) {
                mdelay(1);
                cpu_relax();
        }
}
#endif /* defined(CONFIG_SMP) */

void machine_shutdown(void)
{
#ifdef CONFIG_SMP
        int cpu;

        /* All CPUs go to reboot_code_buffer */
        for_each_possible_cpu(cpu)
                if (!cpu_online(cpu))
                        cpu_device_up(get_cpu_device(cpu));

        smp_call_function(kexec_shutdown_secondary, NULL, 0);
#endif
}

void machine_crash_shutdown(struct pt_regs *regs)
{
        int crashing_cpu;

        local_irq_disable();

        crashing_cpu = smp_processor_id();
        crash_save_cpu(regs, crashing_cpu);

#ifdef CONFIG_SMP
        crash_smp_send_stop();
#endif
        machine_kexec_mask_interrupts();
        cpumask_set_cpu(crashing_cpu, &cpus_in_crash);

        pr_info("Starting crashdump kernel...\n");
}

void machine_kexec(struct kimage *image)
{
        unsigned long entry, *ptr;
        struct kimage_arch *internal = &image->arch;

        efi_boot = internal->efi_boot;
        cmdline_ptr = internal->cmdline_ptr;
        systable_ptr = internal->systable_ptr;

        start_addr = (unsigned long)phys_to_virt(image->start);

        first_ind_entry = (image->type == KEXEC_TYPE_DEFAULT) ?
                (unsigned long)phys_to_virt(image->head & PAGE_MASK) : 0;

        /*
         * The generic kexec code builds a page list with physical
         * addresses. they are directly accessible through XKPRANGE
         * hence the phys_to_virt() call.
         */
        for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
             ptr = (entry & IND_INDIRECTION) ?
               phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
                if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
                    *ptr & IND_DESTINATION)
                        *ptr = (unsigned long) phys_to_virt(*ptr);
        }

        /* Mark offline before disabling local irq. */
        set_cpu_online(smp_processor_id(), false);

        /* We do not want to be bothered. */
        local_irq_disable();
        machine_kexec_mask_interrupts();

        pr_notice("EFI boot flag: 0x%lx\n", efi_boot);
        pr_notice("Command line addr: 0x%lx\n", cmdline_ptr);
        pr_notice("Command line string: %s\n", (char *)cmdline_ptr);
        pr_notice("System table addr: 0x%lx\n", systable_ptr);
        pr_notice("We will call new kernel at 0x%lx\n", start_addr);
        pr_notice("Bye ...\n");

        /* Make reboot code buffer available to the boot CPU. */
        flush_cache_all();

#ifdef CONFIG_SMP
        atomic_set(&kexec_ready_to_reboot, 1);
#endif

        kexec_reboot();
}