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 #include <linux/io.h>
  15
  16 #include <asm/processor.h>
  17 #include <asm/proto.h>
  18 #include <asm/smp.h>
  19 #include <asm/setup.h>
  20 #include <asm/desc.h>
  21 #include <asm/pgtable.h>
  22 #include <asm/tlbflush.h>
  23 #include <asm/sections.h>
  24 #include <asm/kdebug.h>
  25 #include <asm/e820.h>
  26 #include <asm/bios_ebda.h>
  27
  28 static void __init zap_identity_mappings(void)
  29 {
  30         pgd_t *pgd = pgd_offset_k(0UL);
  31         pgd_clear(pgd);
  32         __flush_tlb_all();
  33 }
  34
  35 /* Don't add a printk in there. printk relies on the PDA which is not initialized
  36    yet. */
  37 static void __init clear_bss(void)
  38 {
  39         memset(__bss_start, 0,
  40                (unsigned long) __bss_stop - (unsigned long) __bss_start);
  41 }
  42
  43 static void __init copy_bootdata(char *real_mode_data)
  44 {
  45         char * command_line;
  46
  47         memcpy(&boot_params, real_mode_data, sizeof boot_params);
  48         if (boot_params.hdr.cmd_line_ptr) {
  49                 command_line = __va(boot_params.hdr.cmd_line_ptr);
  50                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
  51         }
  52 }
  53
  54 #define BIOS_LOWMEM_KILOBYTES 0x413
  55
  56 /*
  57  * The BIOS places the EBDA/XBDA at the top of conventional
  58  * memory, and usually decreases the reported amount of
  59  * conventional memory (int 0x12) too. This also contains a
  60  * workaround for Dell systems that neglect to reserve EBDA.
  61  * The same workaround also avoids a problem with the AMD768MPX
  62  * chipset: reserve a page before VGA to prevent PCI prefetch
  63  * into it (errata #56). Usually the page is reserved anyways,
  64  * unless you have no PS/2 mouse plugged in.
  65  */
  66 static void __init reserve_ebda_region(void)
  67 {
  68         unsigned int lowmem, ebda_addr;
  69
  70         /* To determine the position of the EBDA and the */
  71         /* end of conventional memory, we need to look at */
  72         /* the BIOS data area. In a paravirtual environment */
  73         /* that area is absent. We'll just have to assume */
  74         /* that the paravirt case can handle memory setup */
  75         /* correctly, without our help. */
  76         if (paravirt_enabled())
  77                 return;
  78
  79         /* end of low (conventional) memory */
  80         lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
  81         lowmem <<= 10;
  82
  83         /* start of EBDA area */
  84         ebda_addr = get_bios_ebda();
  85
  86         /* Fixup: bios puts an EBDA in the top 64K segment */
  87         /* of conventional memory, but does not adjust lowmem. */
  88         if ((lowmem - ebda_addr) <= 0x10000)
  89                 lowmem = ebda_addr;
  90
  91         /* Fixup: bios does not report an EBDA at all. */
  92         /* Some old Dells seem to need 4k anyhow (bugzilla 2990) */
  93         if ((ebda_addr == 0) && (lowmem >= 0x9f000))
  94                 lowmem = 0x9f000;
  95
  96         /* Paranoia: should never happen, but... */
  97         if ((lowmem == 0) || (lowmem >= 0x100000))
  98                 lowmem = 0x9f000;
  99
 100         /* reserve all memory between lowmem and the 1MB mark */
 101         reserve_early(lowmem, 0x100000, "BIOS reserved");
 102 }
 103
 104 static void __init reserve_setup_data(void)
 105 {
 106         struct setup_data *data;
 107         unsigned long pa_data;
 108         char buf[32];
 109
 110         if (boot_params.hdr.version < 0x0209)
 111                 return;
 112         pa_data = boot_params.hdr.setup_data;
 113         while (pa_data) {
 114                 data = early_ioremap(pa_data, sizeof(*data));
 115                 sprintf(buf, "setup data %x", data->type);
 116                 reserve_early(pa_data, pa_data+sizeof(*data)+data->len, buf);
 117                 pa_data = data->next;
 118                 early_iounmap(data, sizeof(*data));
 119         }
 120 }
 121
 122 void __init x86_64_start_kernel(char * real_mode_data)
 123 {
 124         int i;
 125
 126         /*
 127          * Build-time sanity checks on the kernel image and module
 128          * area mappings. (these are purely build-time and produce no code)
 129          */
 130         BUILD_BUG_ON(MODULES_VADDR < KERNEL_IMAGE_START);
 131         BUILD_BUG_ON(MODULES_VADDR-KERNEL_IMAGE_START < KERNEL_IMAGE_SIZE);
 132         BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 133         BUILD_BUG_ON((KERNEL_IMAGE_START & ~PMD_MASK) != 0);
 134         BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 135         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
 136         BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 137                                 (__START_KERNEL & PGDIR_MASK)));
 138         BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
 139
 140         /* clear bss before set_intr_gate with early_idt_handler */
 141         clear_bss();
 142
 143         /* Make NULL pointers segfault */
 144         zap_identity_mappings();
 145
 146         /* Cleanup the over mapped high alias */
 147         cleanup_highmap();
 148
 149         for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
 150 #ifdef CONFIG_EARLY_PRINTK
 151                 set_intr_gate(i, &early_idt_handlers[i]);
 152 #else
 153                 set_intr_gate(i, early_idt_handler);
 154 #endif
 155         }
 156         load_idt((const struct desc_ptr *)&idt_descr);
 157
 158         early_printk("Kernel alive\n");
 159
 160         for (i = 0; i < NR_CPUS; i++)
 161                 cpu_pda(i) = &boot_cpu_pda[i];
 162
 163         pda_init(0);
 164         copy_bootdata(__va(real_mode_data));
 165
 166         reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
 167
 168 #ifdef CONFIG_BLK_DEV_INITRD
 169         /* Reserve INITRD */
 170         if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
 171                 unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
 172                 unsigned long ramdisk_size  = boot_params.hdr.ramdisk_size;
 173                 unsigned long ramdisk_end   = ramdisk_image + ramdisk_size;
 174                 reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
 175         }
 176 #endif
 177
 178         reserve_ebda_region();
 179         reserve_setup_data();
 180
 181         /*
 182          * At this point everything still needed from the boot loader
 183          * or BIOS or kernel text should be early reserved or marked not
 184          * RAM in e820. All other memory is free game.
 185          */
 186
 187         start_kernel();
 188 }