include/asm-x86/desc_defs.h

   1 /* Written 2000 by Andi Kleen */
   2 #ifndef __ARCH_DESC_DEFS_H
   3 #define __ARCH_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 { unsigned int a, b; };
  25                 struct {
  26                         u16 limit0;
  27                         u16 base0;
  28                         unsigned base1: 8, type: 4, s: 1, dpl: 2, p: 1;
  29                         unsigned limit: 4, avl: 1, l: 1, d: 1, g: 1, base2: 8;
  30                 };
  31
  32         };
  33 } __attribute__((packed));
  34
  35 enum {
  36         GATE_INTERRUPT = 0xE,
  37         GATE_TRAP = 0xF,
  38         GATE_CALL = 0xC,
  39         GATE_TASK = 0x5,
  40 };
  41
  42 // 16byte gate
  43 struct gate_struct64 {
  44         u16 offset_low;
  45         u16 segment;
  46         unsigned ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1;
  47         u16 offset_middle;
  48         u32 offset_high;
  49         u32 zero1;
  50 } __attribute__((packed));
  51
  52 #define PTR_LOW(x) ((unsigned long long)(x) & 0xFFFF)
  53 #define PTR_MIDDLE(x) (((unsigned long long)(x) >> 16) & 0xFFFF)
  54 #define PTR_HIGH(x) ((unsigned long long)(x) >> 32)
  55
  56 enum {
  57         DESC_TSS = 0x9,
  58         DESC_LDT = 0x2,
  59         DESCTYPE_S =    0x10,   /* !system */
  60 };
  61
  62 // LDT or TSS descriptor in the GDT. 16 bytes.
  63 struct ldttss_desc64 {
  64         u16 limit0;
  65         u16 base0;
  66         unsigned base1 : 8, type : 5, dpl : 2, p : 1;
  67         unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
  68         u32 base3;
  69         u32 zero1;
  70 } __attribute__((packed));
  71
  72 #ifdef CONFIG_X86_64
  73 typedef struct gate_struct64 gate_desc;
  74 typedef struct ldttss_desc64 ldt_desc;
  75 typedef struct ldttss_desc64 tss_desc;
  76 #else
  77 typedef struct desc_struct gate_desc;
  78 typedef struct desc_struct ldt_desc;
  79 typedef struct desc_struct tss_desc;
  80 #endif
  81
  82 struct desc_ptr {
  83         unsigned short size;
  84         unsigned long address;
  85 } __attribute__((packed)) ;
  86
  87
  88 #endif /* !__ASSEMBLY__ */
  89
  90 #endif