arch/x86/kernel/head64.c

   1 /*
   2  *  linux/arch/x86_64/kernel/head64.c -- 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
  14 #include <asm/processor.h>
  15 #include <asm/proto.h>
  16 #include <asm/smp.h>
  17 #include <asm/bootsetup.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
  24 static void __init zap_identity_mappings(void)
  25 {
  26         pgd_t *pgd = pgd_offset_k(0UL);
  27         pgd_clear(pgd);
  28         __flush_tlb();
  29 }
  30
  31 /* Don't add a printk in there. printk relies on the PDA which is not initialized
  32    yet. */
  33 static void __init clear_bss(void)
  34 {
  35         memset(__bss_start, 0,
  36                (unsigned long) __bss_stop - (unsigned long) __bss_start);
  37 }
  38
  39 #define NEW_CL_POINTER          0x228   /* Relative to real mode data */
  40 #define OLD_CL_MAGIC_ADDR       0x20
  41 #define OLD_CL_MAGIC            0xA33F
  42 #define OLD_CL_OFFSET           0x22
  43
  44 static void __init copy_bootdata(char *real_mode_data)
  45 {
  46         unsigned long new_data;
  47         char * command_line;
  48
  49         memcpy(x86_boot_params, real_mode_data, BOOT_PARAM_SIZE);
  50         new_data = *(u32 *) (x86_boot_params + NEW_CL_POINTER);
  51         if (!new_data) {
  52                 if (OLD_CL_MAGIC != *(u16 *)(real_mode_data + OLD_CL_MAGIC_ADDR)) {
  53                         return;
  54                 }
  55                 new_data = __pa(real_mode_data) + *(u16 *)(real_mode_data + OLD_CL_OFFSET);
  56         }
  57         command_line = __va(new_data);
  58         memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
  59 }
  60
  61 void __init x86_64_start_kernel(char * real_mode_data)
  62 {
  63         int i;
  64
  65         /* clear bss before set_intr_gate with early_idt_handler */
  66         clear_bss();
  67
  68         /* Make NULL pointers segfault */
  69         zap_identity_mappings();
  70
  71         for (i = 0; i < IDT_ENTRIES; i++)
  72                 set_intr_gate(i, early_idt_handler);
  73         asm volatile("lidt %0" :: "m" (idt_descr));
  74
  75         early_printk("Kernel alive\n");
  76
  77         for (i = 0; i < NR_CPUS; i++)
  78                 cpu_pda(i) = &boot_cpu_pda[i];
  79
  80         pda_init(0);
  81         copy_bootdata(__va(real_mode_data));
  82 #ifdef CONFIG_SMP
  83         cpu_set(0, cpu_online_map);
  84 #endif
  85         start_kernel();
  86 }