head64.c

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/*
 *  prepare to run common code
 *
 *  Copyright (C) 2000 Andrea Arcangeli <[email protected]> SuSE
 */

#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/percpu.h>
#include <linux/start_kernel.h>
#include <linux/io.h>
#include <linux/memblock.h>

#include <asm/processor.h>
#include <asm/proto.h>
#include <asm/smp.h>
#include <asm/setup.h>
#include <asm/desc.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/kdebug.h>
#include <asm/e820.h>
#include <asm/bios_ebda.h>

static void __init zap_identity_mappings(void)
{
    pgd_t *pgd = pgd_offset_k(0UL);
    pgd_clear(pgd);
    __flush_tlb_all();
}

/* Don't add a printk in there. printk relies on the PDA which is not initialized 
   yet. */
static void __init clear_bss(void)
{
    memset(__bss_start, 0,
           (unsigned long) __bss_stop - (unsigned long) __bss_start);
}

static void __init copy_bootdata(char *real_mode_data)
{
    char * command_line;

    memcpy(&boot_params, real_mode_data, sizeof boot_params);
    if (boot_params.hdr.cmd_line_ptr) {
        command_line = __va(boot_params.hdr.cmd_line_ptr);
        memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
    }
}

void __init x86_64_start_kernel(char * real_mode_data)
{
    int i;

    /*
     * Build-time sanity checks on the kernel image and module
     * area mappings. (these are purely build-time and produce no code)
     */
    BUILD_BUG_ON(MODULES_VADDR < KERNEL_IMAGE_START);
    BUILD_BUG_ON(MODULES_VADDR-KERNEL_IMAGE_START < KERNEL_IMAGE_SIZE);
    BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
    BUILD_BUG_ON((KERNEL_IMAGE_START & ~PMD_MASK) != 0);
    BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
    BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
    BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
                (__START_KERNEL & PGDIR_MASK)));
    BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);

    /* clear bss before set_intr_gate with early_idt_handler */
    clear_bss();

    /* Make NULL pointers segfault */
    zap_identity_mappings();

    max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;

    for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
#ifdef CONFIG_EARLY_PRINTK
        set_intr_gate(i, &early_idt_handlers[i]);
#else
        set_intr_gate(i, early_idt_handler);
#endif
    }
    load_idt((const struct desc_ptr *)&idt_descr);

    if (console_loglevel == 10)
        early_printk("Kernel alive\n");

    x86_64_start_reservations(real_mode_data);
}

void __init x86_64_start_reservations(char *real_mode_data)
{
    copy_bootdata(__va(real_mode_data));

    memblock_reserve(__pa_symbol(&_text),
             __pa_symbol(&__bss_stop) - __pa_symbol(&_text));

#ifdef CONFIG_BLK_DEV_INITRD
    /* Reserve INITRD */
    if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
        /* Assume only end is not page aligned */
        unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
        unsigned long ramdisk_size  = boot_params.hdr.ramdisk_size;
        unsigned long ramdisk_end   = PAGE_ALIGN(ramdisk_image + ramdisk_size);
        memblock_reserve(ramdisk_image, ramdisk_end - ramdisk_image);
    }
#endif

    reserve_ebda_region();

    /*
     * At this point everything still needed from the boot loader
     * or BIOS or kernel text should be early reserved or marked not
     * RAM in e820. All other memory is free game.
     */

    start_kernel();
}