arch/x86/include/asm/desc_defs.h

   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 */
  22 struct 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
  37 enum {
  38         GATE_INTERRUPT = 0xE,
  39         GATE_TRAP = 0xF,
  40         GATE_CALL = 0xC,
  41         GATE_TASK = 0x5,
  42 };
  43
  44 /* 16byte gate */
  45 struct 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
  58 enum {
  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. */
  65 struct 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
  75 typedef struct gate_struct64 gate_desc;
  76 typedef struct ldttss_desc64 ldt_desc;
  77 typedef 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
  81 typedef struct desc_struct gate_desc;
  82 typedef struct desc_struct ldt_desc;
  83 typedef 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
  88 struct 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 */