LXR linux/arch/x86/include/asm/desc

   1/* Written 2000 by Andi Kleen */
   2#ifndef _ASM_X86_DESC_DEFS_H
   3#define _ASM_X86_DESC_DEFS_H
   4
   5/*
   6 * Segment descriptor structure definitions, usable from both x86_64 and i386
   7 * archs.
   8 */
   9
  10#ifndef __ASSEMBLY__
  11
  12#include <linux/types.h>
  13
  14/*
  15 * FIXME: Acessing the desc_struct through its fields is more elegant,
  16 * and should be the one valid thing to do. However, a lot of open code
  17 * still touches the a and b acessors, and doing this allow us to do it
  18 * incrementally. We keep the signature as a struct, rather than an union,
  19 * so we can get rid of it transparently in the future -- glommer
  20 */
  21/* 8 byte segment descriptor */
  22struct desc_struct {
  23        union {
  24                struct {
  25                        unsigned int a;
  26                        unsigned int b;
  27                };
  28                struct {
  29                        u16 limit0;
  30                        u16 base0;
  31                        unsigned base1: 8, type: 4, s: 1, dpl: 2, p: 1;
  32                        unsigned limit: 4, avl: 1, l: 1, d: 1, g: 1, base2: 8;
  33                };
  34        };
  35} __attribute__((packed));
  36
  37enum {
  38        GATE_INTERRUPT = 0xE,
  39        GATE_TRAP = 0xF,
  40        GATE_CALL = 0xC,
  41        GATE_TASK = 0x5,
  42};
  43
  44/* 16byte gate */
  45struct gate_struct64 {
  46        u16 offset_low;
  47        u16 segment;
  48        unsigned ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1;
  49        u16 offset_middle;
  50        u32 offset_high;
  51        u32 zero1;
  52} __attribute__((packed));
  53
  54#define PTR_LOW(x) ((unsigned long long)(x) & 0xFFFF)
  55#define PTR_MIDDLE(x) (((unsigned long long)(x) >> 16) & 0xFFFF)
  56#define PTR_HIGH(x) ((unsigned long long)(x) >> 32)
  57
  58enum {
  59        DESC_TSS = 0x9,
  60        DESC_LDT = 0x2,
  61        DESCTYPE_S = 0x10,      /* !system */
  62};
  63
  64/* LDT or TSS descriptor in the GDT. 16 bytes. */
  65struct ldttss_desc64 {
  66        u16 limit0;
  67        u16 base0;
  68        unsigned base1 : 8, type : 5, dpl : 2, p : 1;
  69        unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
  70        u32 base3;
  71        u32 zero1;
  72} __attribute__((packed));
  73
  74#ifdef CONFIG_X86_64
  75typedef struct gate_struct64 gate_desc;
  76typedef struct ldttss_desc64 ldt_desc;
  77typedef struct ldttss_desc64 tss_desc;
  78#define gate_offset(g) ((g).offset_low | ((unsigned long)(g).offset_middle << 16) | ((unsigned long)(g).offset_high << 32))
  79#define gate_segment(g) ((g).segment)
  80#else
  81typedef struct desc_struct gate_desc;
  82typedef struct desc_struct ldt_desc;
  83typedef struct desc_struct tss_desc;
  84#define gate_offset(g)          (((g).b & 0xffff0000) | ((g).a & 0x0000ffff))
  85#define gate_segment(g)         ((g).a >> 16)
  86#endif
  87
  88struct desc_ptr {
  89        unsigned short size;
  90        unsigned long address;
  91} __attribute__((packed)) ;
  92
  93#endif /* !__ASSEMBLY__ */
  94
  95#endif /* _ASM_X86_DESC_DEFS_H */
  96