include/asm-i386/segment.h

   1 #ifndef _ASM_SEGMENT_H
   2 #define _ASM_SEGMENT_H
   3
   4 /*
   5  * The layout of the per-CPU GDT under Linux:
   6  *
   7  *   0 - null
   8  *   1 - reserved
   9  *   2 - reserved
  10  *   3 - reserved
  11  *
  12  *   4 - unused                 <==== new cacheline
  13  *   5 - unused
  14  *
  15  *  ------- start of TLS (Thread-Local Storage) segments:
  16  *
  17  *   6 - TLS segment #1                 [ glibc's TLS segment ]
  18  *   7 - TLS segment #2                 [ Wine's %fs Win32 segment ]
  19  *   8 - TLS segment #3
  20  *   9 - reserved
  21  *  10 - reserved
  22  *  11 - reserved
  23  *
  24  *  ------- start of kernel segments:
  25  *
  26  *  12 - kernel code segment            <==== new cacheline
  27  *  13 - kernel data segment
  28  *  14 - default user CS
  29  *  15 - default user DS
  30  *  16 - TSS
  31  *  17 - LDT
  32  *  18 - PNPBIOS support (16->32 gate)
  33  *  19 - PNPBIOS support
  34  *  20 - PNPBIOS support
  35  *  21 - PNPBIOS support
  36  *  22 - PNPBIOS support
  37  *  23 - APM BIOS support
  38  *  24 - APM BIOS support
  39  *  25 - APM BIOS support
  40  *
  41  *  26 - unused
  42  *  27 - unused
  43  *  28 - unused
  44  *  29 - unused
  45  *  30 - unused
  46  *  31 - TSS for double fault handler
  47  */
  48 #define GDT_ENTRY_TLS_ENTRIES   3
  49 #define GDT_ENTRY_TLS_MIN       6
  50 #define GDT_ENTRY_TLS_MAX       (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)
  51
  52 #define TLS_SIZE (GDT_ENTRY_TLS_ENTRIES * 8)
  53
  54 #define GDT_ENTRY_DEFAULT_USER_CS       14
  55 #define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS * 8 + 3)
  56
  57 #define GDT_ENTRY_DEFAULT_USER_DS       15
  58 #define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS * 8 + 3)
  59
  60 #define GDT_ENTRY_KERNEL_BASE   12
  61
  62 #define GDT_ENTRY_KERNEL_CS             (GDT_ENTRY_KERNEL_BASE + 0)
  63 #define __KERNEL_CS (GDT_ENTRY_KERNEL_CS * 8)
  64
  65 #define GDT_ENTRY_KERNEL_DS             (GDT_ENTRY_KERNEL_BASE + 1)
  66 #define __KERNEL_DS (GDT_ENTRY_KERNEL_DS * 8)
  67
  68 #define GDT_ENTRY_TSS                   (GDT_ENTRY_KERNEL_BASE + 4)
  69 #define GDT_ENTRY_LDT                   (GDT_ENTRY_KERNEL_BASE + 5)
  70
  71 #define GDT_ENTRY_PNPBIOS_BASE          (GDT_ENTRY_KERNEL_BASE + 6)
  72 #define GDT_ENTRY_APMBIOS_BASE          (GDT_ENTRY_KERNEL_BASE + 11)
  73
  74 #define GDT_ENTRY_DOUBLEFAULT_TSS       31
  75
  76 /*
  77  * The GDT has 32 entries
  78  */
  79 #define GDT_ENTRIES 32
  80
  81 #define GDT_SIZE (GDT_ENTRIES * 8)
  82
  83 /* Simple and small GDT entries for booting only */
  84
  85 #define GDT_ENTRY_BOOT_CS               2
  86 #define __BOOT_CS       (GDT_ENTRY_BOOT_CS * 8)
  87
  88 #define GDT_ENTRY_BOOT_DS               (GDT_ENTRY_BOOT_CS + 1)
  89 #define __BOOT_DS       (GDT_ENTRY_BOOT_DS * 8)
  90
  91 /*
  92  * The interrupt descriptor table has room for 256 idt's,
  93  * the global descriptor table is dependent on the number
  94  * of tasks we can have..
  95  */
  96 #define IDT_ENTRIES 256
  97
  98 #endif