machine_kexec_32.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/delay.h>
#include <linux/init.h>
#include <linux/numa.h>
#include <linux/ftrace.h>
#include <linux/suspend.h>
#include <linux/gfp.h>
#include <linux/io.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/apic.h>
#include <asm/cpufeature.h>
#include <asm/desc.h>
#include <asm/cacheflush.h>
#include <asm/debugreg.h>

static void set_idt(void *newidt, __u16 limit)
{
    struct desc_ptr curidt;

    /* ia32 supports unaliged loads & stores */
    curidt.size    = limit;
    curidt.address = (unsigned long)newidt;

    load_idt(&curidt);
}


static void set_gdt(void *newgdt, __u16 limit)
{
    struct desc_ptr curgdt;

    /* ia32 supports unaligned loads & stores */
    curgdt.size    = limit;
    curgdt.address = (unsigned long)newgdt;

    load_gdt(&curgdt);
}

static void load_segments(void)
{
#define __STR(X) #X
#define STR(X) __STR(X)

    __asm__ __volatile__ (
        "\tljmp $"STR(__KERNEL_CS)",$1f\n"
        "\t1:\n"
        "\tmovl $"STR(__KERNEL_DS)",%%eax\n"
        "\tmovl %%eax,%%ds\n"
        "\tmovl %%eax,%%es\n"
        "\tmovl %%eax,%%fs\n"
        "\tmovl %%eax,%%gs\n"
        "\tmovl %%eax,%%ss\n"
        : : : "eax", "memory");
#undef STR
#undef __STR
}

static void machine_kexec_free_page_tables(struct kimage *image)
{
    free_page((unsigned long)image->arch.pgd);
#ifdef CONFIG_X86_PAE
    free_page((unsigned long)image->arch.pmd0);
    free_page((unsigned long)image->arch.pmd1);
#endif
    free_page((unsigned long)image->arch.pte0);
    free_page((unsigned long)image->arch.pte1);
}

static int machine_kexec_alloc_page_tables(struct kimage *image)
{
    image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
#ifdef CONFIG_X86_PAE
    image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
    image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
#endif
    image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
    image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
    if (!image->arch.pgd ||
#ifdef CONFIG_X86_PAE
        !image->arch.pmd0 || !image->arch.pmd1 ||
#endif
        !image->arch.pte0 || !image->arch.pte1) {
        machine_kexec_free_page_tables(image);
        return -ENOMEM;
    }
    return 0;
}

static void machine_kexec_page_table_set_one(
    pgd_t *pgd, pmd_t *pmd, pte_t *pte,
    unsigned long vaddr, unsigned long paddr)
{
    pud_t *pud;

    pgd += pgd_index(vaddr);
#ifdef CONFIG_X86_PAE
    if (!(pgd_val(*pgd) & _PAGE_PRESENT))
        set_pgd(pgd, __pgd(__pa(pmd) | _PAGE_PRESENT));
#endif
    pud = pud_offset(pgd, vaddr);
    pmd = pmd_offset(pud, vaddr);
    if (!(pmd_val(*pmd) & _PAGE_PRESENT))
        set_pmd(pmd, __pmd(__pa(pte) | _PAGE_TABLE));
    pte = pte_offset_kernel(pmd, vaddr);
    set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
}

static void machine_kexec_prepare_page_tables(struct kimage *image)
{
    void *control_page;
    pmd_t *pmd = NULL;

    control_page = page_address(image->control_code_page);
#ifdef CONFIG_X86_PAE
    pmd = image->arch.pmd0;
#endif
    machine_kexec_page_table_set_one(
        image->arch.pgd, pmd, image->arch.pte0,
        (unsigned long)control_page, __pa(control_page));
#ifdef CONFIG_X86_PAE
    pmd = image->arch.pmd1;
#endif
    machine_kexec_page_table_set_one(
        image->arch.pgd, pmd, image->arch.pte1,
        __pa(control_page), __pa(control_page));
}

/*
 * A architecture hook called to validate the
 * proposed image and prepare the control pages
 * as needed.  The pages for KEXEC_CONTROL_PAGE_SIZE
 * have been allocated, but the segments have yet
 * been copied into the kernel.
 *
 * Do what every setup is needed on image and the
 * reboot code buffer to allow us to avoid allocations
 * later.
 *
 * - Make control page executable.
 * - Allocate page tables
 * - Setup page tables
 */
int machine_kexec_prepare(struct kimage *image)
{
    int error;

    set_pages_x(image->control_code_page, 1);
    error = machine_kexec_alloc_page_tables(image);
    if (error)
        return error;
    machine_kexec_prepare_page_tables(image);
    return 0;
}

/*
 * Undo anything leftover by machine_kexec_prepare
 * when an image is freed.
 */
void machine_kexec_cleanup(struct kimage *image)
{
    set_pages_nx(image->control_code_page, 1);
    machine_kexec_free_page_tables(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;
    asmlinkage unsigned long
        (*relocate_kernel_ptr)(unsigned long indirection_page,
                       unsigned long control_page,
                       unsigned long start_address,
                       unsigned int has_pae,
                       unsigned int preserve_context);

#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);
    memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);

    relocate_kernel_ptr = control_page;
    page_list[PA_CONTROL_PAGE] = __pa(control_page);
    page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
    page_list[PA_PGD] = __pa(image->arch.pgd);

    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_ptr((unsigned long)image->head,
                       (unsigned long)page_list,
                       image->start, cpu_has_pae,
                       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)
{
#ifdef CONFIG_NUMA
    VMCOREINFO_SYMBOL(node_data);
    VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
#endif
#ifdef CONFIG_X86_PAE
    VMCOREINFO_CONFIG(X86_PAE);
#endif
}