1/* Written 2000 by Andi Kleen */
2#ifndef __ARCH_DESC_H
3#define __ARCH_DESC_H
4
5#include <linux/threads.h>
6#include <asm/ldt.h>
7
8#ifndef __ASSEMBLY__
9
10#define __TSS_INDEX(n)  ((n)*64)
11#define __LDT_INDEX(n)  ((n)*64)
12
13extern __u8 gdt_table[];
14extern __u8 gdt_end[];
15
16enum {
17	GATE_INTERRUPT = 0xE,
18	GATE_TRAP = 0xF,
19	GATE_CALL = 0xC,
20};
21
22// 16byte gate
23struct gate_struct {
24	u16 offset_low;
25	u16 segment;
26	unsigned ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1;
27	u16 offset_middle;
28	u32 offset_high;
29	u32 zero1;
30} __attribute__((packed));
31
32// 8 byte segment descriptor
33struct desc_struct {
34	u16 limit0;
35	u16 base0;
36	unsigned base1 : 8, type : 4, s : 1, dpl : 2, p : 1;
37	unsigned limit : 4, avl : 1, l : 1, d : 1, g : 1, base2 : 8;
38} __attribute__((packed));
39
40// LDT or TSS descriptor in the GDT. 16 bytes.
41struct ldttss_desc {
42	u16 limit0;
43	u16 base0;
44	unsigned base1 : 8, type : 5, dpl : 2, p : 1;
45	unsigned limit1 : 4, zero0 : 3, g : 1, base2 : 8;
46	u32 base3;
47	u32 zero1;
48} __attribute__((packed));
49
50
51struct per_cpu_gdt {
52	struct ldttss_desc tss;
53	struct ldttss_desc ldt;
54} ____cacheline_aligned;
55
56extern struct per_cpu_gdt gdt_cpu_table[];
57
58#define PTR_LOW(x) ((unsigned long)(x) & 0xFFFF)
59#define PTR_MIDDLE(x) (((unsigned long)(x) >> 16) & 0xFFFF)
60#define PTR_HIGH(x) ((unsigned long)(x) >> 32)
61
62enum {
63	DESC_TSS = 0x9,
64	DESC_LDT = 0x2,
65};
66
67struct desc_ptr {
68	unsigned short size;
69	unsigned long address;
70} __attribute__((packed)) ;
71
72#define __GDT_HEAD_SIZE 64
73#define __CPU_DESC_INDEX(x,field) \
74	((x) * sizeof(struct per_cpu_gdt) + offsetof(struct per_cpu_gdt, field) + __GDT_HEAD_SIZE)
75
76#define load_TR(cpu) asm volatile("ltr %w0"::"r" (__CPU_DESC_INDEX(cpu, tss)));
77#define __load_LDT(cpu) asm volatile("lldt %w0"::"r" (__CPU_DESC_INDEX(cpu, ldt)));
78#define clear_LDT(n)  asm volatile("lldt %w0"::"r" (0))
79
80extern struct gate_struct idt_table[];
81
82#define copy_16byte(dst,src)  memcpy((dst), (src), 16)
83
84static inline void _set_gate(void *adr, unsigned type, unsigned long func, unsigned dpl, unsigned ist)
85{
86	struct gate_struct s;
87	s.offset_low = PTR_LOW(func);
88	s.segment = __KERNEL_CS;
89	s.ist = ist;
90	s.p = 1;
91	s.dpl = dpl;
92	s.zero0 = 0;
93	s.zero1 = 0;
94	s.type = type;
95	s.offset_middle = PTR_MIDDLE(func);
96	s.offset_high = PTR_HIGH(func);
97	copy_16byte(adr, &s);
98}
99
100static inline void set_intr_gate(int nr, void *func)
101{
102	_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, 0);
103}
104
105static inline void set_intr_gate_ist(int nr, void *func, unsigned ist)
106{
107	_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, ist);
108}
109
110static inline void set_system_gate(int nr, void *func)
111{
112	_set_gate(&idt_table[nr], GATE_INTERRUPT, (unsigned long) func, 3, 0);
113}
114
115static inline void set_tssldt_descriptor(struct ldttss_desc *dst, unsigned long ptr, unsigned type,
116					 unsigned size)
117{
118	memset(dst,0,16);
119	dst->limit0 = size & 0xFFFF;
120	dst->base0 = PTR_LOW(ptr);
121	dst->base1 = PTR_MIDDLE(ptr) & 0xFF;
122	dst->type = type;
123	dst->p = 1;
124	dst->limit1 = 0xF;
125	dst->base2 = (PTR_MIDDLE(ptr) >> 8) & 0xFF;
126	dst->base3 = PTR_HIGH(ptr);
127}
128
129static inline void set_tss_desc(unsigned n, void *addr)
130{
131	set_tssldt_descriptor((void *)&gdt_table + __CPU_DESC_INDEX(n,tss), (unsigned long)addr, DESC_TSS, sizeof(struct tss_struct));
132}
133
134static inline void set_ldt_desc(unsigned n, void *addr, int size)
135{
136	set_tssldt_descriptor((void *)&gdt_table + __CPU_DESC_INDEX(n,ldt), (unsigned long)addr, DESC_LDT, size);
137}
138
139/*
140 * load one particular LDT into the current CPU
141 */
142static inline void load_LDT (struct mm_struct *mm)
143{
144	int cpu = smp_processor_id();
145	void *segments = mm->context.segments;
146
147	if (!segments) {
148		clear_LDT(cpu);
149		return;
150	}
151
152	set_ldt_desc(cpu, segments, LDT_ENTRIES);
153	__load_LDT(cpu);
154}
155
156#endif /* !__ASSEMBLY__ */
157
158#endif
159