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
91
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