desc_defs.h revision bb8985586b7a906e116db835c64773b7a7d51663 
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