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 #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 */