machine_kexec_64.c

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/*
 * handle transition of Linux booting another kernel
 * Copyright (C) 2002-2005 Eric Biederman  <[email protected]>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#include <linux/mm.h>
#include <linux/kexec.h>
#include <linux/string.h>
#include <linux/gfp.h>
#include <linux/reboot.h>
#include <linux/numa.h>
#include <linux/ftrace.h>
#include <linux/io.h>
#include <linux/suspend.h>

#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/debugreg.h>

static int init_one_level2_page(struct kimage *image, pgd_t *pgd,
                unsigned long addr)
{
    pud_t *pud;
    pmd_t *pmd;
    struct page *page;
    int result = -ENOMEM;

    addr &= PMD_MASK;
    pgd += pgd_index(addr);
    if (!pgd_present(*pgd)) {
        page = kimage_alloc_control_pages(image, 0);
        if (!page)
            goto out;
        pud = (pud_t *)page_address(page);
        clear_page(pud);
        set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
    }
    pud = pud_offset(pgd, addr);
    if (!pud_present(*pud)) {
        page = kimage_alloc_control_pages(image, 0);
        if (!page)
            goto out;
        pmd = (pmd_t *)page_address(page);
        clear_page(pmd);
        set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
    }
    pmd = pmd_offset(pud, addr);
    if (!pmd_present(*pmd))
        set_pmd(pmd, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
    result = 0;
out:
    return result;
}

static void init_level2_page(pmd_t *level2p, unsigned long addr)
{
    unsigned long end_addr;

    addr &= PAGE_MASK;
    end_addr = addr + PUD_SIZE;
    while (addr < end_addr) {
        set_pmd(level2p++, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
        addr += PMD_SIZE;
    }
}

static int init_level3_page(struct kimage *image, pud_t *level3p,
                unsigned long addr, unsigned long last_addr)
{
    unsigned long end_addr;
    int result;

    result = 0;
    addr &= PAGE_MASK;
    end_addr = addr + PGDIR_SIZE;
    while ((addr < last_addr) && (addr < end_addr)) {
        struct page *page;
        pmd_t *level2p;

        page = kimage_alloc_control_pages(image, 0);
        if (!page) {
            result = -ENOMEM;
            goto out;
        }
        level2p = (pmd_t *)page_address(page);
        init_level2_page(level2p, addr);
        set_pud(level3p++, __pud(__pa(level2p) | _KERNPG_TABLE));
        addr += PUD_SIZE;
    }
    /* clear the unused entries */
    while (addr < end_addr) {
        pud_clear(level3p++);
        addr += PUD_SIZE;
    }
out:
    return result;
}


static int init_level4_page(struct kimage *image, pgd_t *level4p,
                unsigned long addr, unsigned long last_addr)
{
    unsigned long end_addr;
    int result;

    result = 0;
    addr &= PAGE_MASK;
    end_addr = addr + (PTRS_PER_PGD * PGDIR_SIZE);
    while ((addr < last_addr) && (addr < end_addr)) {
        struct page *page;
        pud_t *level3p;

        page = kimage_alloc_control_pages(image, 0);
        if (!page) {
            result = -ENOMEM;
            goto out;
        }
        level3p = (pud_t *)page_address(page);
        result = init_level3_page(image, level3p, addr, last_addr);
        if (result)
            goto out;
        set_pgd(level4p++, __pgd(__pa(level3p) | _KERNPG_TABLE));
        addr += PGDIR_SIZE;
    }
    /* clear the unused entries */
    while (addr < end_addr) {
        pgd_clear(level4p++);
        addr += PGDIR_SIZE;
    }
out:
    return result;
}

static void free_transition_pgtable(struct kimage *image)
{
    free_page((unsigned long)image->arch.pud);
    free_page((unsigned long)image->arch.pmd);
    free_page((unsigned long)image->arch.pte);
}

static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
{
    pud_t *pud;
    pmd_t *pmd;
    pte_t *pte;
    unsigned long vaddr, paddr;
    int result = -ENOMEM;

    vaddr = (unsigned long)relocate_kernel;
    paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
    pgd += pgd_index(vaddr);
    if (!pgd_present(*pgd)) {
        pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
        if (!pud)
            goto err;
        image->arch.pud = pud;
        set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
    }
    pud = pud_offset(pgd, vaddr);
    if (!pud_present(*pud)) {
        pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
        if (!pmd)
            goto err;
        image->arch.pmd = pmd;
        set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
    }
    pmd = pmd_offset(pud, vaddr);
    if (!pmd_present(*pmd)) {
        pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
        if (!pte)
            goto err;
        image->arch.pte = pte;
        set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
    }
    pte = pte_offset_kernel(pmd, vaddr);
    set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
    return 0;
err:
    free_transition_pgtable(image);
    return result;
}


static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
{
    pgd_t *level4p;
    int result;
    level4p = (pgd_t *)__va(start_pgtable);
    result = init_level4_page(image, level4p, 0, max_pfn << PAGE_SHIFT);
    if (result)
        return result;
    /*
     * image->start may be outside 0 ~ max_pfn, for example when
     * jump back to original kernel from kexeced kernel
     */
    result = init_one_level2_page(image, level4p, image->start);
    if (result)
        return result;
    return init_transition_pgtable(image, level4p);
}

static void set_idt(void *newidt, u16 limit)
{
    struct desc_ptr curidt;

    /* x86-64 supports unaliged loads & stores */
    curidt.size    = limit;
    curidt.address = (unsigned long)newidt;

    __asm__ __volatile__ (
        "lidtq %0\n"
        : : "m" (curidt)
        );
};


static void set_gdt(void *newgdt, u16 limit)
{
    struct desc_ptr curgdt;

    /* x86-64 supports unaligned loads & stores */
    curgdt.size    = limit;
    curgdt.address = (unsigned long)newgdt;

    __asm__ __volatile__ (
        "lgdtq %0\n"
        : : "m" (curgdt)
        );
};

static void load_segments(void)
{
    __asm__ __volatile__ (
        "\tmovl %0,%%ds\n"
        "\tmovl %0,%%es\n"
        "\tmovl %0,%%ss\n"
        "\tmovl %0,%%fs\n"
        "\tmovl %0,%%gs\n"
        : : "a" (__KERNEL_DS) : "memory"
        );
}

int machine_kexec_prepare(struct kimage *image)
{
    unsigned long start_pgtable;
    int result;

    /* Calculate the offsets */
    start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;

    /* Setup the identity mapped 64bit page table */
    result = init_pgtable(image, start_pgtable);
    if (result)
        return result;

    return 0;
}

void machine_kexec_cleanup(struct kimage *image)
{
    free_transition_pgtable(image);
}

/*
 * Do not allocate memory (or fail in any way) in machine_kexec().
 * We are past the point of no return, committed to rebooting now.
 */
void machine_kexec(struct kimage *image)
{
    unsigned long page_list[PAGES_NR];
    void *control_page;
    int save_ftrace_enabled;

#ifdef CONFIG_KEXEC_JUMP
    if (image->preserve_context)
        save_processor_state();
#endif

    save_ftrace_enabled = __ftrace_enabled_save();

    /* Interrupts aren't acceptable while we reboot */
    local_irq_disable();
    hw_breakpoint_disable();

    if (image->preserve_context) {
#ifdef CONFIG_X86_IO_APIC
        /*
         * We need to put APICs in legacy mode so that we can
         * get timer interrupts in second kernel. kexec/kdump
         * paths already have calls to disable_IO_APIC() in
         * one form or other. kexec jump path also need
         * one.
         */
        disable_IO_APIC();
#endif
    }

    control_page = page_address(image->control_code_page) + PAGE_SIZE;
    memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);

    page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
    page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
    page_list[PA_TABLE_PAGE] =
      (unsigned long)__pa(page_address(image->control_code_page));

    if (image->type == KEXEC_TYPE_DEFAULT)
        page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
                        << PAGE_SHIFT);

    /*
     * The segment registers are funny things, they have both a
     * visible and an invisible part.  Whenever the visible part is
     * set to a specific selector, the invisible part is loaded
     * with from a table in memory.  At no other time is the
     * descriptor table in memory accessed.
     *
     * I take advantage of this here by force loading the
     * segments, before I zap the gdt with an invalid value.
     */
    load_segments();
    /*
     * The gdt & idt are now invalid.
     * If you want to load them you must set up your own idt & gdt.
     */
    set_gdt(phys_to_virt(0), 0);
    set_idt(phys_to_virt(0), 0);

    /* now call it */
    image->start = relocate_kernel((unsigned long)image->head,
                       (unsigned long)page_list,
                       image->start,
                       image->preserve_context);

#ifdef CONFIG_KEXEC_JUMP
    if (image->preserve_context)
        restore_processor_state();
#endif

    __ftrace_enabled_restore(save_ftrace_enabled);
}

void arch_crash_save_vmcoreinfo(void)
{
    VMCOREINFO_SYMBOL(phys_base);
    VMCOREINFO_SYMBOL(init_level4_pgt);

#ifdef CONFIG_NUMA
    VMCOREINFO_SYMBOL(node_data);
    VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
#endif
}