arch/x86/kernel/head64.c

   1 /*
   2  *  prepare to run common code
   3  *
   4  *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
   5  */
   6
   7 #include <linux/init.h>
   8 #include <linux/linkage.h>
   9 #include <linux/types.h>
  10 #include <linux/kernel.h>
  11 #include <linux/string.h>
  12 #include <linux/percpu.h>
  13 #include <linux/start_kernel.h>
  14
  15 #include <asm/processor.h>
  16 #include <asm/proto.h>
  17 #include <asm/smp.h>
  18 #include <asm/setup.h>
  19 #include <asm/desc.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/sections.h>
  23 #include <asm/kdebug.h>
  24 #include <asm/e820.h>
  25
  26 static void __init zap_identity_mappings(void)
  27 {
  28         pgd_t *pgd = pgd_offset_k(0UL);
  29         pgd_clear(pgd);
  30         __flush_tlb_all();
  31 }
  32
  33 /* Don't add a printk in there. printk relies on the PDA which is not initialized
  34    yet. */
  35 static void __init clear_bss(void)
  36 {
  37         memset(__bss_start, 0,
  38                (unsigned long) __bss_stop - (unsigned long) __bss_start);
  39 }
  40
  41 static void __init copy_bootdata(char *real_mode_data)
  42 {
  43         char * command_line;
  44
  45         memcpy(&boot_params, real_mode_data, sizeof boot_params);
  46         if (boot_params.hdr.cmd_line_ptr) {
  47                 command_line = __va(boot_params.hdr.cmd_line_ptr);
  48                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
  49         }
  50 }
  51
  52 #define EBDA_ADDR_POINTER 0x40E
  53
  54 static __init void reserve_ebda(void)
  55 {
  56         unsigned ebda_addr, ebda_size;
  57
  58         /*
  59          * there is a real-mode segmented pointer pointing to the
  60          * 4K EBDA area at 0x40E
  61          */
  62         ebda_addr = *(unsigned short *)__va(EBDA_ADDR_POINTER);
  63         ebda_addr <<= 4;
  64
  65         if (!ebda_addr)
  66                 return;
  67
  68         ebda_size = *(unsigned short *)__va(ebda_addr);
  69
  70         /* Round EBDA up to pages */
  71         if (ebda_size == 0)
  72                 ebda_size = 1;
  73         ebda_size <<= 10;
  74         ebda_size = round_up(ebda_size + (ebda_addr & ~PAGE_MASK), PAGE_SIZE);
  75         if (ebda_size > 64*1024)
  76                 ebda_size = 64*1024;
  77
  78         reserve_early(ebda_addr, ebda_addr + ebda_size);
  79 }
  80
  81 void __init x86_64_start_kernel(char * real_mode_data)
  82 {
  83         int i;
  84
  85         /* clear bss before set_intr_gate with early_idt_handler */
  86         clear_bss();
  87
  88         /* Make NULL pointers segfault */
  89         zap_identity_mappings();
  90
  91         for (i = 0; i < IDT_ENTRIES; i++) {
  92 #ifdef CONFIG_EARLY_PRINTK
  93                 set_intr_gate(i, &early_idt_handlers[i]);
  94 #else
  95                 set_intr_gate(i, early_idt_handler);
  96 #endif
  97         }
  98         load_idt((const struct desc_ptr *)&idt_descr);
  99
 100         early_printk("Kernel alive\n");
 101
 102         for (i = 0; i < NR_CPUS; i++)
 103                 cpu_pda(i) = &boot_cpu_pda[i];
 104
 105         pda_init(0);
 106         copy_bootdata(__va(real_mode_data));
 107
 108         reserve_early(__pa_symbol(&_text), __pa_symbol(&_end));
 109
 110         /* Reserve INITRD */
 111         if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
 112                 unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
 113                 unsigned long ramdisk_size  = boot_params.hdr.ramdisk_size;
 114                 unsigned long ramdisk_end   = ramdisk_image + ramdisk_size;
 115                 reserve_early(ramdisk_image, ramdisk_end);
 116         }
 117
 118         reserve_ebda();
 119
 120         /*
 121          * At this point everything still needed from the boot loader
 122          * or BIOS or kernel text should be early reserved or marked not
 123          * RAM in e820. All other memory is free game.
 124          */
 125
 126         start_kernel();
 127 }