machine_kexec.c

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/*
 * 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 <asm/pgtable.h>
#include <linux/of_fdt.h>
#include <asm/pgalloc.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/mach-types.h>
#include <asm/system_misc.h>

extern const unsigned char relocate_new_kernel[];
extern const unsigned int relocate_new_kernel_size;

extern unsigned long kexec_start_address;
extern unsigned long kexec_indirection_page;
extern unsigned long kexec_mach_type;
extern unsigned long kexec_boot_atags;

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;

    /*
     * 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(current_segment->mem,
                           current_segment->memsz))
            return -EINVAL;

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

        if (be32_to_cpu(header) == OF_DT_HEADER)
            kexec_boot_atags = current_segment->mem;
    }
    return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
}

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

    crash_setup_regs(&regs, NULL);
    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();

    atomic_dec(&waiting_for_crash_ipi);
    while (1)
        cpu_relax();
}

static void machine_kexec_mask_interrupts(void)
{
    unsigned int i;
    struct irq_desc *desc;

    for_each_irq_desc(i, desc) {
        struct irq_chip *chip;

        chip = irq_desc_get_chip(desc);
        if (!chip)
            continue;

        if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
            chip->irq_eoi(&desc->irq_data);

        if (chip->irq_mask)
            chip->irq_mask(&desc->irq_data);

        if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
            chip->irq_disable(&desc->irq_data);
    }
}

void machine_crash_shutdown(struct pt_regs *regs)
{
    unsigned long msecs;

    local_irq_disable();

    atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
    smp_call_function(machine_crash_nonpanic_core, NULL, false);
    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)
        printk(KERN_WARNING "Non-crashing CPUs did not react to IPI\n");

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

    printk(KERN_INFO "Loading crashdump kernel...\n");
}

/*
 * Function pointer to optional machine-specific reinitialization
 */
void (*kexec_reinit)(void);

void machine_kexec(struct kimage *image)
{
    unsigned long page_list;
    unsigned long reboot_code_buffer_phys;
    void *reboot_code_buffer;


    page_list = image->head & PAGE_MASK;

    /* we need both effective and real address here */
    reboot_code_buffer_phys =
        page_to_pfn(image->control_code_page) << PAGE_SHIFT;
    reboot_code_buffer = page_address(image->control_code_page);

    /* Prepare parameters for reboot_code_buffer*/
    kexec_start_address = image->start;
    kexec_indirection_page = page_list;
    kexec_mach_type = machine_arch_type;
    if (!kexec_boot_atags)
        kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET;


    /* copy our kernel relocation code to the control code page */
    memcpy(reboot_code_buffer,
           relocate_new_kernel, relocate_new_kernel_size);


    flush_icache_range((unsigned long) reboot_code_buffer,
               (unsigned long) reboot_code_buffer + KEXEC_CONTROL_PAGE_SIZE);
    printk(KERN_INFO "Bye!\n");

    if (kexec_reinit)
        kexec_reinit();

    soft_restart(reboot_code_buffer_phys);
}