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  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: Accessing 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 accessors, 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. #define GDT_ENTRY_INIT(flags, base, limit) { { { \
  38.                 .a = ((limit) & 0xffff) | (((base) & 0xffff) << 16), \
  39.                 .b = (((base) & 0xff0000) >> 16) | (((flags) & 0xf0ff) << 8) | \
  40.                         ((limit) & 0xf0000) | ((base) & 0xff000000), \
  41.         } } }
  42.  
  43. enum {
  44.         GATE_INTERRUPT = 0xE,
  45.         GATE_TRAP = 0xF,
  46.         GATE_CALL = 0xC,
  47.         GATE_TASK = 0x5,
  48. };
  49.  
  50. /* 16byte gate */
  51. struct gate_struct64 {
  52.         u16 offset_low;
  53.         u16 segment;
  54.         unsigned ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1;
  55.         u16 offset_middle;
  56.         u32 offset_high;
  57.         u32 zero1;
  58. } __attribute__((packed));
  59.  
  60. #define PTR_LOW(x) ((unsigned long long)(x) & 0xFFFF)
  61. #define PTR_MIDDLE(x) (((unsigned long long)(x) >> 16) & 0xFFFF)
  62. #define PTR_HIGH(x) ((unsigned long long)(x) >> 32)
  63.  
  64. enum {
  65.         DESC_TSS = 0x9,
  66.         DESC_LDT = 0x2,
  67.         DESCTYPE_S = 0x10,      /* !system */
  68. };
  69.  
  70. /* LDT or TSS descriptor in the GDT. 16 bytes. */
  71. struct ldttss_desc64 {
  72.         u16 limit0;
  73.         u16 base0;
  74.         unsigned base1 : 8, type : 5, dpl : 2, p : 1;
  75.         unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
  76.         u32 base3;
  77.         u32 zero1;
  78. } __attribute__((packed));
  79.  
  80. #ifdef CONFIG_X86_64
  81. typedef struct gate_struct64 gate_desc;
  82. typedef struct ldttss_desc64 ldt_desc;
  83. typedef struct ldttss_desc64 tss_desc;
  84. #define gate_offset(g) ((g).offset_low | ((unsigned long)(g).offset_middle << 16) | ((unsigned long)(g).offset_high << 32))
  85. #define gate_segment(g) ((g).segment)
  86. #else
  87. typedef struct desc_struct gate_desc;
  88. typedef struct desc_struct ldt_desc;
  89. typedef struct desc_struct tss_desc;
  90. #define gate_offset(g)          (((g).b & 0xffff0000) | ((g).a & 0x0000ffff))
  91. #define gate_segment(g)         ((g).a >> 16)
  92. #endif
  93.  
  94. struct desc_ptr {
  95.         unsigned short size;
  96.         unsigned long address;
  97. } __attribute__((packed)) ;
  98.  
  99. #endif /* !__ASSEMBLY__ */
  100.  
  101. #endif /* _ASM_X86_DESC_DEFS_H */
  102.