OLD | NEW |
| (Empty) |
1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 /* | |
6 * Definition of MiniDisassembler. | |
7 */ | |
8 | |
9 #ifndef GOOGLE_PERFTOOLS_MINI_DISASSEMBLER_H__ | |
10 #define GOOGLE_PERFTOOLS_MINI_DISASSEMBLER_H__ | |
11 | |
12 #include <windows.h> | |
13 #include "mini_disassembler_types.h" | |
14 | |
15 // compatibility shim | |
16 #include "base/logging.h" | |
17 #define ASSERT(cond, msg) DCHECK(cond) | |
18 #define ASSERT1(cond) DCHECK(cond) | |
19 | |
20 namespace sidestep { | |
21 | |
22 // This small disassembler is very limited | |
23 // in its functionality, and in fact does only the bare minimum required by the | |
24 // preamble patching utility. It may be useful for other purposes, however. | |
25 // | |
26 // The limitations include at least the following: | |
27 // -# No support for coprocessor opcodes, MMX, etc. | |
28 // -# No machine-readable identification of opcodes or decoding of | |
29 // assembly parameters. The name of the opcode (as a string) is given, | |
30 // however, to aid debugging. | |
31 // | |
32 // You may ask what this little disassembler actually does, then? The answer is | |
33 // that it does the following, which is exactly what the patching utility needs: | |
34 // -# Indicates if opcode is a jump (any kind) or a return (any kind) | |
35 // because this is important for the patching utility to determine if | |
36 // a function is too short or there are jumps too early in it for it | |
37 // to be preamble patched. | |
38 // -# The opcode length is always calculated, so that the patching utility | |
39 // can figure out where the next instruction starts, and whether it | |
40 // already has enough instructions to replace with the absolute jump | |
41 // to the patching code. | |
42 // | |
43 // The usage is quite simple; just create a MiniDisassembler and use its | |
44 // Disassemble() method. | |
45 // | |
46 // If you would like to extend this disassembler, please refer to the | |
47 // IA-32 Intel Architecture Software Developer's Manual Volume 2: | |
48 // Instruction Set Reference for information about operand decoding | |
49 // etc. | |
50 class MiniDisassembler { | |
51 public: | |
52 | |
53 // Creates a new instance and sets defaults. | |
54 // | |
55 // @param operand_default_32_bits If true, the default operand size is | |
56 // set to 32 bits, which is the default under Win32. Otherwise it is 16 bits. | |
57 // @param address_default_32_bits If true, the default address size is | |
58 // set to 32 bits, which is the default under Win32. Otherwise it is 16 bits. | |
59 MiniDisassembler(bool operand_default_32_bits, | |
60 bool address_default_32_bits); | |
61 | |
62 // Equivalent to MiniDisassembler(true, true); | |
63 MiniDisassembler(); | |
64 | |
65 // Attempts to disassemble a single instruction starting from the | |
66 // address in memory it is pointed to. | |
67 // | |
68 // @param start Address where disassembly should start. | |
69 // @param instruction_bytes Variable that will be <b>incremented</b> by | |
70 // the length in bytes of the instruction. | |
71 // @return enItJump, enItReturn or enItGeneric on success. enItUnknown | |
72 // if unable to disassemble, enItUnused if this seems to be an unused | |
73 // opcode. In the last two (error) cases, cbInstruction will be set | |
74 // to 0xffffffff. | |
75 // | |
76 // @post This instance of the disassembler is ready to be used again, | |
77 // with unchanged defaults from creation time. | |
78 InstructionType Disassemble(unsigned char* start, unsigned int& instruction_by
tes); | |
79 | |
80 private: | |
81 | |
82 // Makes the disassembler ready for reuse. | |
83 void Initialize(); | |
84 | |
85 // Sets the flags for address and operand sizes. | |
86 // @return Number of prefix bytes. | |
87 InstructionType ProcessPrefixes(unsigned char* start, unsigned int& size); | |
88 | |
89 // Sets the flag for whether we have ModR/M, and increments | |
90 // operand_bytes_ if any are specifies by the opcode directly. | |
91 // @return Number of opcode bytes. | |
92 InstructionType ProcessOpcode(unsigned char * start, | |
93 unsigned int table, | |
94 unsigned int& size); | |
95 | |
96 // Checks the type of the supplied operand. Increments | |
97 // operand_bytes_ if it directly indicates an immediate etc. | |
98 // operand. Asserts have_modrm_ if the operand specifies | |
99 // a ModR/M byte. | |
100 bool ProcessOperand(int flag_operand); | |
101 | |
102 // Increments operand_bytes_ by size specified by ModR/M and | |
103 // by SIB if present. | |
104 // @return 0 in case of error, 1 if there is just a ModR/M byte, | |
105 // 2 if there is a ModR/M byte and a SIB byte. | |
106 bool ProcessModrm(unsigned char* start, unsigned int& size); | |
107 | |
108 // Processes the SIB byte that it is pointed to. | |
109 // @param start Pointer to the SIB byte. | |
110 // @param mod The mod field from the ModR/M byte. | |
111 // @return 1 to indicate success (indicates 1 SIB byte) | |
112 bool ProcessSib(unsigned char* start, unsigned char mod, unsigned int& size); | |
113 | |
114 // The instruction type we have decoded from the opcode. | |
115 InstructionType instruction_type_; | |
116 | |
117 // Counts the number of bytes that is occupied by operands in | |
118 // the current instruction (note: we don't care about how large | |
119 // operands stored in registers etc. are). | |
120 unsigned int operand_bytes_; | |
121 | |
122 // True iff there is a ModR/M byte in this instruction. | |
123 bool have_modrm_; | |
124 | |
125 // True iff we need to decode the ModR/M byte (sometimes it just | |
126 // points to a register, we can tell by the addressing mode). | |
127 bool should_decode_modrm_; | |
128 | |
129 // Current operand size is 32 bits if true, 16 bits if false. | |
130 bool operand_is_32_bits_; | |
131 | |
132 // Default operand size is 32 bits if true, 16 bits if false. | |
133 bool operand_default_is_32_bits_; | |
134 | |
135 // Current address size is 32 bits if true, 16 bits if false. | |
136 bool address_is_32_bits_; | |
137 | |
138 // Default address size is 32 bits if true, 16 bits if false. | |
139 bool address_default_is_32_bits_; | |
140 | |
141 // Huge big opcode table based on the IA-32 manual, defined | |
142 // in Ia32OpcodeMap.cc | |
143 static const OpcodeTable s_ia32_opcode_map_[]; | |
144 | |
145 // Somewhat smaller table to help with decoding ModR/M bytes | |
146 // when 16-bit addressing mode is being used. Defined in | |
147 // Ia32ModrmMap.cc | |
148 static const ModrmEntry s_ia16_modrm_map_[]; | |
149 | |
150 // Somewhat smaller table to help with decoding ModR/M bytes | |
151 // when 32-bit addressing mode is being used. Defined in | |
152 // Ia32ModrmMap.cc | |
153 static const ModrmEntry s_ia32_modrm_map_[]; | |
154 | |
155 // Indicators of whether we got certain prefixes that certain | |
156 // silly Intel instructions depend on in nonstandard ways for | |
157 // their behaviors. | |
158 bool got_f2_prefix_, got_f3_prefix_, got_66_prefix_; | |
159 }; | |
160 | |
161 }; // namespace sidestep | |
162 | |
163 #endif // GOOGLE_PERFTOOLS_MINI_DISASSEMBLER_H__ | |
OLD | NEW |