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| 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__ | |
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