// SPDX-License-Identifier: GPL-2.0
/*
 * machine_kexec.c - handle transition of Linux booting another kernel
 */

#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/memblock.h>
#include <linux/of_fdt.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/kexec-internal.h>
#include <asm/fncpy.h>
#include <asm/mach-types.h>
#include <asm/smp_plat.h>
#include <asm/system_misc.h>
#include <asm/set_memory.h>

extern void relocate_new_kernel(void);
extern const unsigned int relocate_new_kernel_size;

static atomic_t waiting_for_crash_ipi;

/*
 * Provide a dummy crash_notes definition while crash dump arrives to arm.
 * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
 */

int machine_kexec_prepare(struct kimage *image)
{
        struct kexec_segment *current_segment;
        __be32 header;
        int i, err;

        image->arch.kernel_r2 = image->start - KEXEC_ARM_ZIMAGE_OFFSET
                                     + KEXEC_ARM_ATAGS_OFFSET;

        /*
         * Validate that if the current HW supports SMP, then the SW supports
         * and implements CPU hotplug for the current HW. If not, we won't be
         * able to kexec reliably, so fail the prepare operation.
         */
        if (num_possible_cpus() > 1 && platform_can_secondary_boot() &&
            !platform_can_cpu_hotplug())
                return -EINVAL;

        /*
         * No segment at default ATAGs address. try to locate
         * a dtb using magic.
         */
        for (i = 0; i < image->nr_segments; i++) {
                current_segment = &image->segment[i];

                if (!memblock_is_region_memory(idmap_to_phys(current_segment->mem),
                                               current_segment->memsz))
                        return -EINVAL;

                err = get_user(header, (__be32*)current_segment->buf);
                if (err)
                        return err;

                if (header == cpu_to_be32(OF_DT_HEADER))
                        image->arch.kernel_r2 = current_segment->mem;
        }
        return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
}

static void machine_crash_nonpanic_core(void *unused)
{
        struct pt_regs regs;

        local_fiq_disable();

        crash_setup_regs(&regs, get_irq_regs());
        printk(KERN_DEBUG "CPU %u will stop doing anything useful since another CPU has crashed\n",
               smp_processor_id());
        crash_save_cpu(&regs, smp_processor_id());
        flush_cache_all();

        set_cpu_online(smp_processor_id(), false);
        atomic_dec(&waiting_for_crash_ipi);

        while (1) {
                cpu_relax();
                wfe();
        }
}

static DEFINE_PER_CPU(call_single_data_t, cpu_stop_csd) =
        CSD_INIT(machine_crash_nonpanic_core, NULL);

void crash_smp_send_stop(void)
{
        static int cpus_stopped;
        unsigned long msecs;
        call_single_data_t *csd;
        int cpu, this_cpu = raw_smp_processor_id();

        if (cpus_stopped)
                return;

        atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
        for_each_online_cpu(cpu) {
                if (cpu == this_cpu)
                        continue;

                csd = &per_cpu(cpu_stop_csd, cpu);
                smp_call_function_single_async(cpu, csd);
        }

        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--;
        }
        if (atomic_read(&waiting_for_crash_ipi) > 0)
                pr_warn("Non-crashing CPUs did not react to IPI\n");

        cpus_stopped = 1;
}

void machine_crash_shutdown(struct pt_regs *regs)
{
        local_irq_disable();
        crash_smp_send_stop();

        crash_save_cpu(regs, smp_processor_id());
        machine_kexec_mask_interrupts();

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

void machine_kexec(struct kimage *image)
{
        unsigned long page_list, reboot_entry_phys;
        struct kexec_relocate_data *data;
        void (*reboot_entry)(void);
        void *reboot_code_buffer;

        /*
         * This can only happen if machine_shutdown() failed to disable some
         * CPU, and that can only happen if the checks in
         * machine_kexec_prepare() were not correct. If this fails, we can't
         * reliably kexec anyway, so BUG_ON is appropriate.
         */
        BUG_ON(num_online_cpus() > 1);

        page_list = image->head & PAGE_MASK;

        reboot_code_buffer = page_address(image->control_code_page);

        /* copy our kernel relocation code to the control code page */
        reboot_entry = fncpy(reboot_code_buffer,
                             &relocate_new_kernel,
                             relocate_new_kernel_size);

        data = reboot_code_buffer + relocate_new_kernel_size;
        data->kexec_start_address = image->start;
        data->kexec_indirection_page = page_list;
        data->kexec_mach_type = machine_arch_type;
        data->kexec_r2 = image->arch.kernel_r2;

        /* get the identity mapping physical address for the reboot code */
        reboot_entry_phys = virt_to_idmap(reboot_entry);

        pr_info("Bye!\n");

        soft_restart(reboot_entry_phys);
}