Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see <http://www.gnu.org/licenses/>.
16 */
17
18#include <stdio.h>
19#include <stdlib.h>
20
21#define unlikely(cond) (cond)
22#include "insn/insn.h"
23#include "insn/inat.c"
24#include "insn/insn.c"
25
26#include "../../elf.h"
27#include "../../arch.h"
28#include "../../warn.h"
29
30static int is_x86_64(struct elf *elf)
31{
32 switch (elf->ehdr.e_machine) {
33 case EM_X86_64:
34 return 1;
35 case EM_386:
36 return 0;
37 default:
38 WARN("unexpected ELF machine type %d", elf->ehdr.e_machine);
39 return -1;
40 }
41}
42
43int arch_decode_instruction(struct elf *elf, struct section *sec,
44 unsigned long offset, unsigned int maxlen,
45 unsigned int *len, unsigned char *type,
46 unsigned long *immediate)
47{
48 struct insn insn;
49 int x86_64;
50 unsigned char op1, op2, ext;
51
52 x86_64 = is_x86_64(elf);
53 if (x86_64 == -1)
54 return -1;
55
56 insn_init(&insn, (void *)(sec->data + offset), maxlen, x86_64);
57 insn_get_length(&insn);
58 insn_get_opcode(&insn);
59 insn_get_modrm(&insn);
60 insn_get_immediate(&insn);
61
62 if (!insn_complete(&insn)) {
63 WARN_FUNC("can't decode instruction", sec, offset);
64 return -1;
65 }
66
67 *len = insn.length;
68 *type = INSN_OTHER;
69
70 if (insn.vex_prefix.nbytes)
71 return 0;
72
73 op1 = insn.opcode.bytes[0];
74 op2 = insn.opcode.bytes[1];
75
76 switch (op1) {
77 case 0x55:
78 if (!insn.rex_prefix.nbytes)
79 /* push rbp */
80 *type = INSN_FP_SAVE;
81 break;
82
83 case 0x5d:
84 if (!insn.rex_prefix.nbytes)
85 /* pop rbp */
86 *type = INSN_FP_RESTORE;
87 break;
88
89 case 0x70 ... 0x7f:
90 *type = INSN_JUMP_CONDITIONAL;
91 break;
92
93 case 0x89:
94 if (insn.rex_prefix.nbytes == 1 &&
95 insn.rex_prefix.bytes[0] == 0x48 &&
96 insn.modrm.nbytes && insn.modrm.bytes[0] == 0xe5)
97 /* mov rsp, rbp */
98 *type = INSN_FP_SETUP;
99 break;
100
101 case 0x8d:
102 if (insn.rex_prefix.nbytes &&
103 insn.rex_prefix.bytes[0] == 0x48 &&
104 insn.modrm.nbytes && insn.modrm.bytes[0] == 0x2c &&
105 insn.sib.nbytes && insn.sib.bytes[0] == 0x24)
106 /* lea %(rsp), %rbp */
107 *type = INSN_FP_SETUP;
108 break;
109
110 case 0x90:
111 *type = INSN_NOP;
112 break;
113
114 case 0x0f:
115 if (op2 >= 0x80 && op2 <= 0x8f)
116 *type = INSN_JUMP_CONDITIONAL;
117 else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 ||
118 op2 == 0x35)
119 /* sysenter, sysret */
120 *type = INSN_CONTEXT_SWITCH;
121 else if (op2 == 0x0d || op2 == 0x1f)
122 /* nopl/nopw */
123 *type = INSN_NOP;
124 else if (op2 == 0x01 && insn.modrm.nbytes &&
125 (insn.modrm.bytes[0] == 0xc2 ||
126 insn.modrm.bytes[0] == 0xd8))
127 /* vmlaunch, vmrun */
128 *type = INSN_CONTEXT_SWITCH;
129
130 break;
131
132 case 0xc9: /* leave */
133 *type = INSN_FP_RESTORE;
134 break;
135
136 case 0xe3: /* jecxz/jrcxz */
137 *type = INSN_JUMP_CONDITIONAL;
138 break;
139
140 case 0xe9:
141 case 0xeb:
142 *type = INSN_JUMP_UNCONDITIONAL;
143 break;
144
145 case 0xc2:
146 case 0xc3:
147 *type = INSN_RETURN;
148 break;
149
150 case 0xca: /* retf */
151 case 0xcb: /* retf */
152 case 0xcf: /* iret */
153 *type = INSN_CONTEXT_SWITCH;
154 break;
155
156 case 0xe8:
157 *type = INSN_CALL;
158 break;
159
160 case 0xff:
161 ext = X86_MODRM_REG(insn.modrm.bytes[0]);
162 if (ext == 2 || ext == 3)
163 *type = INSN_CALL_DYNAMIC;
164 else if (ext == 4)
165 *type = INSN_JUMP_DYNAMIC;
166 else if (ext == 5) /*jmpf */
167 *type = INSN_CONTEXT_SWITCH;
168
169 break;
170
171 default:
172 break;
173 }
174
175 *immediate = insn.immediate.nbytes ? insn.immediate.value : 0;
176
177 return 0;
178}