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 - ESPFIX small SS
  42  *  27 - per-cpu                        [ offset to per-cpu data area ]
  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_ESPFIX_SS             (GDT_ENTRY_KERNEL_BASE + 14)
  75 #define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8)
  76
  77 #define GDT_ENTRY_PERCPU                        (GDT_ENTRY_KERNEL_BASE + 15)
  78 #ifdef CONFIG_SMP
  79 #define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8)
  80 #else
  81 #define __KERNEL_PERCPU 0
  82 #endif
  83
  84 #define GDT_ENTRY_DOUBLEFAULT_TSS       31
  85
  86 /*
  87  * The GDT has 32 entries
  88  */
  89 #define GDT_ENTRIES 32
  90 #define GDT_SIZE (GDT_ENTRIES * 8)
  91
  92 /* Simple and small GDT entries for booting only */
  93
  94 #define GDT_ENTRY_BOOT_CS               2
  95 #define __BOOT_CS       (GDT_ENTRY_BOOT_CS * 8)
  96
  97 #define GDT_ENTRY_BOOT_DS               (GDT_ENTRY_BOOT_CS + 1)
  98 #define __BOOT_DS       (GDT_ENTRY_BOOT_DS * 8)
  99
 100 /* The PnP BIOS entries in the GDT */
 101 #define GDT_ENTRY_PNPBIOS_CS32          (GDT_ENTRY_PNPBIOS_BASE + 0)
 102 #define GDT_ENTRY_PNPBIOS_CS16          (GDT_ENTRY_PNPBIOS_BASE + 1)
 103 #define GDT_ENTRY_PNPBIOS_DS            (GDT_ENTRY_PNPBIOS_BASE + 2)
 104 #define GDT_ENTRY_PNPBIOS_TS1           (GDT_ENTRY_PNPBIOS_BASE + 3)
 105 #define GDT_ENTRY_PNPBIOS_TS2           (GDT_ENTRY_PNPBIOS_BASE + 4)
 106
 107 /* The PnP BIOS selectors */
 108 #define PNP_CS32   (GDT_ENTRY_PNPBIOS_CS32 * 8) /* segment for calling fn */
 109 #define PNP_CS16   (GDT_ENTRY_PNPBIOS_CS16 * 8) /* code segment for BIOS */
 110 #define PNP_DS     (GDT_ENTRY_PNPBIOS_DS * 8)   /* data segment for BIOS */
 111 #define PNP_TS1    (GDT_ENTRY_PNPBIOS_TS1 * 8)  /* transfer data segment */
 112 #define PNP_TS2    (GDT_ENTRY_PNPBIOS_TS2 * 8)  /* another data segment */
 113
 114 /*
 115  * The interrupt descriptor table has room for 256 idt's,
 116  * the global descriptor table is dependent on the number
 117  * of tasks we can have..
 118  */
 119 #define IDT_ENTRIES 256
 120
 121 /* Bottom two bits of selector give the ring privilege level */
 122 #define SEGMENT_RPL_MASK        0x3
 123 /* Bit 2 is table indicator (LDT/GDT) */
 124 #define SEGMENT_TI_MASK         0x4
 125
 126 /* User mode is privilege level 3 */
 127 #define USER_RPL                0x3
 128 /* LDT segment has TI set, GDT has it cleared */
 129 #define SEGMENT_LDT             0x4
 130 #define SEGMENT_GDT             0x0
 131
 132 #ifndef CONFIG_PARAVIRT
 133 #define get_kernel_rpl()  0
 134 #endif
 135 /*
 136  * Matching rules for certain types of segments.
 137  */
 138
 139 /* Matches only __KERNEL_CS, ignoring PnP / USER / APM segments */
 140 #define SEGMENT_IS_KERNEL_CODE(x) (((x) & 0xfc) == GDT_ENTRY_KERNEL_CS * 8)
 141
 142 /* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */
 143 #define SEGMENT_IS_FLAT_CODE(x)  (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8)
 144
 145 /* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
 146 #define SEGMENT_IS_PNP_CODE(x)   (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)
 147
 148 #endif