tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2#ifndef _ASM_X86_INSN_H
3#define _ASM_X86_INSN_H
4/*
5 * x86 instruction analysis
6 *
7 * Copyright (C) IBM Corporation, 2009
8 */
9
10/* insn_attr_t is defined in inat.h */
11#include <asm/inat.h>
12
13struct insn_field {
14 union {
15 insn_value_t value;
16 insn_byte_t bytes[4];
17 };
18 /* !0 if we've run insn_get_xxx() for this field */
19 unsigned char got;
20 unsigned char nbytes;
21};
22
23struct insn {
24 struct insn_field prefixes; /*
25 * Prefixes
26 * prefixes.bytes[3]: last prefix
27 */
28 struct insn_field rex_prefix; /* REX prefix */
29 struct insn_field vex_prefix; /* VEX prefix */
30 struct insn_field opcode; /*
31 * opcode.bytes[0]: opcode1
32 * opcode.bytes[1]: opcode2
33 * opcode.bytes[2]: opcode3
34 */
35 struct insn_field modrm;
36 struct insn_field sib;
37 struct insn_field displacement;
38 union {
39 struct insn_field immediate;
40 struct insn_field moffset1; /* for 64bit MOV */
41 struct insn_field immediate1; /* for 64bit imm or off16/32 */
42 };
43 union {
44 struct insn_field moffset2; /* for 64bit MOV */
45 struct insn_field immediate2; /* for 64bit imm or seg16 */
46 };
47
48 insn_attr_t attr;
49 unsigned char opnd_bytes;
50 unsigned char addr_bytes;
51 unsigned char length;
52 unsigned char x86_64;
53
54 const insn_byte_t *kaddr; /* kernel address of insn to analyze */
55 const insn_byte_t *end_kaddr; /* kernel address of last insn in buffer */
56 const insn_byte_t *next_byte;
57};
58
59#define MAX_INSN_SIZE 15
60
61#define X86_MODRM_MOD(modrm) (((modrm) & 0xc0) >> 6)
62#define X86_MODRM_REG(modrm) (((modrm) & 0x38) >> 3)
63#define X86_MODRM_RM(modrm) ((modrm) & 0x07)
64
65#define X86_SIB_SCALE(sib) (((sib) & 0xc0) >> 6)
66#define X86_SIB_INDEX(sib) (((sib) & 0x38) >> 3)
67#define X86_SIB_BASE(sib) ((sib) & 0x07)
68
69#define X86_REX_W(rex) ((rex) & 8)
70#define X86_REX_R(rex) ((rex) & 4)
71#define X86_REX_X(rex) ((rex) & 2)
72#define X86_REX_B(rex) ((rex) & 1)
73
74/* VEX bit flags */
75#define X86_VEX_W(vex) ((vex) & 0x80) /* VEX3 Byte2 */
76#define X86_VEX_R(vex) ((vex) & 0x80) /* VEX2/3 Byte1 */
77#define X86_VEX_X(vex) ((vex) & 0x40) /* VEX3 Byte1 */
78#define X86_VEX_B(vex) ((vex) & 0x20) /* VEX3 Byte1 */
79#define X86_VEX_L(vex) ((vex) & 0x04) /* VEX3 Byte2, VEX2 Byte1 */
80/* VEX bit fields */
81#define X86_EVEX_M(vex) ((vex) & 0x03) /* EVEX Byte1 */
82#define X86_VEX3_M(vex) ((vex) & 0x1f) /* VEX3 Byte1 */
83#define X86_VEX2_M 1 /* VEX2.M always 1 */
84#define X86_VEX_V(vex) (((vex) & 0x78) >> 3) /* VEX3 Byte2, VEX2 Byte1 */
85#define X86_VEX_P(vex) ((vex) & 0x03) /* VEX3 Byte2, VEX2 Byte1 */
86#define X86_VEX_M_MAX 0x1f /* VEX3.M Maximum value */
87
88extern void insn_init(struct insn *insn, const void *kaddr, int buf_len, int x86_64);
89extern void insn_get_prefixes(struct insn *insn);
90extern void insn_get_opcode(struct insn *insn);
91extern void insn_get_modrm(struct insn *insn);
92extern void insn_get_sib(struct insn *insn);
93extern void insn_get_displacement(struct insn *insn);
94extern void insn_get_immediate(struct insn *insn);
95extern void insn_get_length(struct insn *insn);
96
97/* Attribute will be determined after getting ModRM (for opcode groups) */
98static inline void insn_get_attribute(struct insn *insn)
99{
100 insn_get_modrm(insn);
101}
102
103/* Instruction uses RIP-relative addressing */
104extern int insn_rip_relative(struct insn *insn);
105
106/* Init insn for kernel text */
107static inline void kernel_insn_init(struct insn *insn,
108 const void *kaddr, int buf_len)
109{
110#ifdef CONFIG_X86_64
111 insn_init(insn, kaddr, buf_len, 1);
112#else /* CONFIG_X86_32 */
113 insn_init(insn, kaddr, buf_len, 0);
114#endif
115}
116
117static inline int insn_is_avx(struct insn *insn)
118{
119 if (!insn->prefixes.got)
120 insn_get_prefixes(insn);
121 return (insn->vex_prefix.value != 0);
122}
123
124static inline int insn_is_evex(struct insn *insn)
125{
126 if (!insn->prefixes.got)
127 insn_get_prefixes(insn);
128 return (insn->vex_prefix.nbytes == 4);
129}
130
131/* Ensure this instruction is decoded completely */
132static inline int insn_complete(struct insn *insn)
133{
134 return insn->opcode.got && insn->modrm.got && insn->sib.got &&
135 insn->displacement.got && insn->immediate.got;
136}
137
138static inline insn_byte_t insn_vex_m_bits(struct insn *insn)
139{
140 if (insn->vex_prefix.nbytes == 2) /* 2 bytes VEX */
141 return X86_VEX2_M;
142 else if (insn->vex_prefix.nbytes == 3) /* 3 bytes VEX */
143 return X86_VEX3_M(insn->vex_prefix.bytes[1]);
144 else /* EVEX */
145 return X86_EVEX_M(insn->vex_prefix.bytes[1]);
146}
147
148static inline insn_byte_t insn_vex_p_bits(struct insn *insn)
149{
150 if (insn->vex_prefix.nbytes == 2) /* 2 bytes VEX */
151 return X86_VEX_P(insn->vex_prefix.bytes[1]);
152 else
153 return X86_VEX_P(insn->vex_prefix.bytes[2]);
154}
155
156/* Get the last prefix id from last prefix or VEX prefix */
157static inline int insn_last_prefix_id(struct insn *insn)
158{
159 if (insn_is_avx(insn))
160 return insn_vex_p_bits(insn); /* VEX_p is a SIMD prefix id */
161
162 if (insn->prefixes.bytes[3])
163 return inat_get_last_prefix_id(insn->prefixes.bytes[3]);
164
165 return 0;
166}
167
168/* Offset of each field from kaddr */
169static inline int insn_offset_rex_prefix(struct insn *insn)
170{
171 return insn->prefixes.nbytes;
172}
173static inline int insn_offset_vex_prefix(struct insn *insn)
174{
175 return insn_offset_rex_prefix(insn) + insn->rex_prefix.nbytes;
176}
177static inline int insn_offset_opcode(struct insn *insn)
178{
179 return insn_offset_vex_prefix(insn) + insn->vex_prefix.nbytes;
180}
181static inline int insn_offset_modrm(struct insn *insn)
182{
183 return insn_offset_opcode(insn) + insn->opcode.nbytes;
184}
185static inline int insn_offset_sib(struct insn *insn)
186{
187 return insn_offset_modrm(insn) + insn->modrm.nbytes;
188}
189static inline int insn_offset_displacement(struct insn *insn)
190{
191 return insn_offset_sib(insn) + insn->sib.nbytes;
192}
193static inline int insn_offset_immediate(struct insn *insn)
194{
195 return insn_offset_displacement(insn) + insn->displacement.nbytes;
196}
197
198#define POP_SS_OPCODE 0x1f
199#define MOV_SREG_OPCODE 0x8e
200
201/*
202 * Intel SDM Vol.3A 6.8.3 states;
203 * "Any single-step trap that would be delivered following the MOV to SS
204 * instruction or POP to SS instruction (because EFLAGS.TF is 1) is
205 * suppressed."
206 * This function returns true if @insn is MOV SS or POP SS. On these
207 * instructions, single stepping is suppressed.
208 */
209static inline int insn_masking_exception(struct insn *insn)
210{
211 return insn->opcode.bytes[0] == POP_SS_OPCODE ||
212 (insn->opcode.bytes[0] == MOV_SREG_OPCODE &&
213 X86_MODRM_REG(insn->modrm.bytes[0]) == 2);
214}
215
216#endif /* _ASM_X86_INSN_H */