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diff --git a/sandbox/src/sidestep/mini_disassembler.cpp b/sandbox/src/sidestep/mini_disassembler.cpp
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--- a/sandbox/src/sidestep/mini_disassembler.cpp
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-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Implementation of MiniDisassembler.
-
-#ifdef _WIN64
-#error The code in this file should not be used on 64-bit Windows.
-#endif
-
-#include "sandbox/src/sidestep/mini_disassembler.h"
-
-namespace sidestep {
-
-MiniDisassembler::MiniDisassembler(bool operand_default_is_32_bits,
- bool address_default_is_32_bits)
- : operand_default_is_32_bits_(operand_default_is_32_bits),
- address_default_is_32_bits_(address_default_is_32_bits) {
- Initialize();
-}
-
-MiniDisassembler::MiniDisassembler()
- : operand_default_is_32_bits_(true),
- address_default_is_32_bits_(true) {
- Initialize();
-}
-
-InstructionType MiniDisassembler::Disassemble(
- unsigned char* start_byte,
- unsigned int* instruction_bytes) {
- // Clean up any state from previous invocations.
- Initialize();
-
- // Start by processing any prefixes.
- unsigned char* current_byte = start_byte;
- unsigned int size = 0;
- InstructionType instruction_type = ProcessPrefixes(current_byte, &size);
-
- if (IT_UNKNOWN == instruction_type)
- return instruction_type;
-
- current_byte += size;
- size = 0;
-
- // Invariant: We have stripped all prefixes, and the operand_is_32_bits_
- // and address_is_32_bits_ flags are correctly set.
-
- instruction_type = ProcessOpcode(current_byte, 0, &size);
-
- // Check for error processing instruction
- if ((IT_UNKNOWN == instruction_type_) || (IT_UNUSED == instruction_type_)) {
- return IT_UNKNOWN;
- }
-
- current_byte += size;
-
- // Invariant: operand_bytes_ indicates the total size of operands
- // specified by the opcode and/or ModR/M byte and/or SIB byte.
- // pCurrentByte points to the first byte after the ModR/M byte, or after
- // the SIB byte if it is present (i.e. the first byte of any operands
- // encoded in the instruction).
-
- // We get the total length of any prefixes, the opcode, and the ModR/M and
- // SIB bytes if present, by taking the difference of the original starting
- // address and the current byte (which points to the first byte of the
- // operands if present, or to the first byte of the next instruction if
- // they are not). Adding the count of bytes in the operands encoded in
- // the instruction gives us the full length of the instruction in bytes.
- *instruction_bytes += operand_bytes_ + (current_byte - start_byte);
-
- // Return the instruction type, which was set by ProcessOpcode().
- return instruction_type_;
-}
-
-void MiniDisassembler::Initialize() {
- operand_is_32_bits_ = operand_default_is_32_bits_;
- address_is_32_bits_ = address_default_is_32_bits_;
- operand_bytes_ = 0;
- have_modrm_ = false;
- should_decode_modrm_ = false;
- instruction_type_ = IT_UNKNOWN;
- got_f2_prefix_ = false;
- got_f3_prefix_ = false;
- got_66_prefix_ = false;
-}
-
-InstructionType MiniDisassembler::ProcessPrefixes(unsigned char* start_byte,
- unsigned int* size) {
- InstructionType instruction_type = IT_GENERIC;
- const Opcode& opcode = s_ia32_opcode_map_[0].table_[*start_byte];
-
- switch (opcode.type_) {
- case IT_PREFIX_ADDRESS:
- address_is_32_bits_ = !address_default_is_32_bits_;
- goto nochangeoperand;
- case IT_PREFIX_OPERAND:
- operand_is_32_bits_ = !operand_default_is_32_bits_;
- nochangeoperand:
- case IT_PREFIX:
-
- if (0xF2 == (*start_byte))
- got_f2_prefix_ = true;
- else if (0xF3 == (*start_byte))
- got_f3_prefix_ = true;
- else if (0x66 == (*start_byte))
- got_66_prefix_ = true;
-
- instruction_type = opcode.type_;
- (*size)++;
- // we got a prefix, so add one and check next byte
- ProcessPrefixes(start_byte + 1, size);
- default:
- break; // not a prefix byte
- }
-
- return instruction_type;
-}
-
-InstructionType MiniDisassembler::ProcessOpcode(unsigned char* start_byte,
- unsigned int table_index,
- unsigned int* size) {
- const OpcodeTable& table = s_ia32_opcode_map_[table_index]; // Get our table
- unsigned char current_byte = (*start_byte) >> table.shift_;
- current_byte = current_byte & table.mask_; // Mask out the bits we will use
-
- // Check whether the byte we have is inside the table we have.
- if (current_byte < table.min_lim_ || current_byte > table.max_lim_) {
- instruction_type_ = IT_UNKNOWN;
- return instruction_type_;
- }
-
- const Opcode& opcode = table.table_[current_byte];
- if (IT_UNUSED == opcode.type_) {
- // This instruction is not used by the IA-32 ISA, so we indicate
- // this to the user. Probably means that we were pointed to
- // a byte in memory that was not the start of an instruction.
- instruction_type_ = IT_UNUSED;
- return instruction_type_;
- } else if (IT_REFERENCE == opcode.type_) {
- // We are looking at an opcode that has more bytes (or is continued
- // in the ModR/M byte). Recursively find the opcode definition in
- // the table for the opcode's next byte.
- (*size)++;
- ProcessOpcode(start_byte + 1, opcode.table_index_, size);
- return instruction_type_;
- }
-
- const SpecificOpcode* specific_opcode = reinterpret_cast<
- const SpecificOpcode*>(&opcode);
- if (opcode.is_prefix_dependent_) {
- if (got_f2_prefix_ && opcode.opcode_if_f2_prefix_.mnemonic_ != 0) {
- specific_opcode = &opcode.opcode_if_f2_prefix_;
- } else if (got_f3_prefix_ && opcode.opcode_if_f3_prefix_.mnemonic_ != 0) {
- specific_opcode = &opcode.opcode_if_f3_prefix_;
- } else if (got_66_prefix_ && opcode.opcode_if_66_prefix_.mnemonic_ != 0) {
- specific_opcode = &opcode.opcode_if_66_prefix_;
- }
- }
-
- // Inv: The opcode type is known.
- instruction_type_ = specific_opcode->type_;
-
- // Let's process the operand types to see if we have any immediate
- // operands, and/or a ModR/M byte.
-
- ProcessOperand(specific_opcode->flag_dest_);
- ProcessOperand(specific_opcode->flag_source_);
- ProcessOperand(specific_opcode->flag_aux_);
-
- // Inv: We have processed the opcode and incremented operand_bytes_
- // by the number of bytes of any operands specified by the opcode
- // that are stored in the instruction (not registers etc.). Now
- // we need to return the total number of bytes for the opcode and
- // for the ModR/M or SIB bytes if they are present.
-
- if (table.mask_ != 0xff) {
- if (have_modrm_) {
- // we're looking at a ModR/M byte so we're not going to
- // count that into the opcode size
- ProcessModrm(start_byte, size);
- return IT_GENERIC;
- } else {
- // need to count the ModR/M byte even if it's just being
- // used for opcode extension
- (*size)++;
- return IT_GENERIC;
- }
- } else {
- if (have_modrm_) {
- // The ModR/M byte is the next byte.
- (*size)++;
- ProcessModrm(start_byte + 1, size);
- return IT_GENERIC;
- } else {
- (*size)++;
- return IT_GENERIC;
- }
- }
-}
-
-bool MiniDisassembler::ProcessOperand(int flag_operand) {
- bool succeeded = true;
- if (AM_NOT_USED == flag_operand)
- return succeeded;
-
- // Decide what to do based on the addressing mode.
- switch (flag_operand & AM_MASK) {
- // No ModR/M byte indicated by these addressing modes, and no
- // additional (e.g. immediate) parameters.
- case AM_A: // Direct address
- case AM_F: // EFLAGS register
- case AM_X: // Memory addressed by the DS:SI register pair
- case AM_Y: // Memory addressed by the ES:DI register pair
- case AM_IMPLICIT: // Parameter is implicit, occupies no space in
- // instruction
- break;
-
- // There is a ModR/M byte but it does not necessarily need
- // to be decoded.
- case AM_C: // reg field of ModR/M selects a control register
- case AM_D: // reg field of ModR/M selects a debug register
- case AM_G: // reg field of ModR/M selects a general register
- case AM_P: // reg field of ModR/M selects an MMX register
- case AM_R: // mod field of ModR/M may refer only to a general register
- case AM_S: // reg field of ModR/M selects a segment register
- case AM_T: // reg field of ModR/M selects a test register
- case AM_V: // reg field of ModR/M selects a 128-bit XMM register
- have_modrm_ = true;
- break;
-
- // In these addressing modes, there is a ModR/M byte and it needs to be
- // decoded. No other (e.g. immediate) params than indicated in ModR/M.
- case AM_E: // Operand is either a general-purpose register or memory,
- // specified by ModR/M byte
- case AM_M: // ModR/M byte will refer only to memory
- case AM_Q: // Operand is either an MMX register or memory (complex
- // evaluation), specified by ModR/M byte
- case AM_W: // Operand is either a 128-bit XMM register or memory (complex
- // eval), specified by ModR/M byte
- have_modrm_ = true;
- should_decode_modrm_ = true;
- break;
-
- // These addressing modes specify an immediate or an offset value
- // directly, so we need to look at the operand type to see how many
- // bytes.
- case AM_I: // Immediate data.
- case AM_J: // Jump to offset.
- case AM_O: // Operand is at offset.
- switch (flag_operand & OT_MASK) {
- case OT_B: // Byte regardless of operand-size attribute.
- operand_bytes_ += OS_BYTE;
- break;
- case OT_C: // Byte or word, depending on operand-size attribute.
- if (operand_is_32_bits_)
- operand_bytes_ += OS_WORD;
- else
- operand_bytes_ += OS_BYTE;
- break;
- case OT_D: // Doubleword, regardless of operand-size attribute.
- operand_bytes_ += OS_DOUBLE_WORD;
- break;
- case OT_DQ: // Double-quadword, regardless of operand-size attribute.
- operand_bytes_ += OS_DOUBLE_QUAD_WORD;
- break;
- case OT_P: // 32-bit or 48-bit pointer, depending on operand-size
- // attribute.
- if (operand_is_32_bits_)
- operand_bytes_ += OS_48_BIT_POINTER;
- else
- operand_bytes_ += OS_32_BIT_POINTER;
- break;
- case OT_PS: // 128-bit packed single-precision floating-point data.
- operand_bytes_ += OS_128_BIT_PACKED_SINGLE_PRECISION_FLOATING;
- break;
- case OT_Q: // Quadword, regardless of operand-size attribute.
- operand_bytes_ += OS_QUAD_WORD;
- break;
- case OT_S: // 6-byte pseudo-descriptor.
- operand_bytes_ += OS_PSEUDO_DESCRIPTOR;
- break;
- case OT_SD: // Scalar Double-Precision Floating-Point Value
- case OT_PD: // Unaligned packed double-precision floating point value
- operand_bytes_ += OS_DOUBLE_PRECISION_FLOATING;
- break;
- case OT_SS:
- // Scalar element of a 128-bit packed single-precision
- // floating data.
- // We simply return enItUnknown since we don't have to support
- // floating point
- succeeded = false;
- break;
- case OT_V: // Word or doubleword, depending on operand-size attribute.
- if (operand_is_32_bits_)
- operand_bytes_ += OS_DOUBLE_WORD;
- else
- operand_bytes_ += OS_WORD;
- break;
- case OT_W: // Word, regardless of operand-size attribute.
- operand_bytes_ += OS_WORD;
- break;
-
- // Can safely ignore these.
- case OT_A: // Two one-word operands in memory or two double-word
- // operands in memory
- case OT_PI: // Quadword MMX technology register (e.g. mm0)
- case OT_SI: // Doubleword integer register (e.g., eax)
- break;
-
- default:
- break;
- }
- break;
-
- default:
- break;
- }
-
- return succeeded;
-}
-
-bool MiniDisassembler::ProcessModrm(unsigned char* start_byte,
- unsigned int* size) {
- // If we don't need to decode, we just return the size of the ModR/M
- // byte (there is never a SIB byte in this case).
- if (!should_decode_modrm_) {
- (*size)++;
- return true;
- }
-
- // We never care about the reg field, only the combination of the mod
- // and r/m fields, so let's start by packing those fields together into
- // 5 bits.
- unsigned char modrm = (*start_byte);
- unsigned char mod = modrm & 0xC0; // mask out top two bits to get mod field
- modrm = modrm & 0x07; // mask out bottom 3 bits to get r/m field
- mod = mod >> 3; // shift the mod field to the right place
- modrm = mod | modrm; // combine the r/m and mod fields as discussed
- mod = mod >> 3; // shift the mod field to bits 2..0
-
- // Invariant: modrm contains the mod field in bits 4..3 and the r/m field
- // in bits 2..0, and mod contains the mod field in bits 2..0
-
- const ModrmEntry* modrm_entry = 0;
- if (address_is_32_bits_)
- modrm_entry = &s_ia32_modrm_map_[modrm];
- else
- modrm_entry = &s_ia16_modrm_map_[modrm];
-
- // Invariant: modrm_entry points to information that we need to decode
- // the ModR/M byte.
-
- // Add to the count of operand bytes, if the ModR/M byte indicates
- // that some operands are encoded in the instruction.
- if (modrm_entry->is_encoded_in_instruction_)
- operand_bytes_ += modrm_entry->operand_size_;
-
- // Process the SIB byte if necessary, and return the count
- // of ModR/M and SIB bytes.
- if (modrm_entry->use_sib_byte_) {
- (*size)++;
- return ProcessSib(start_byte + 1, mod, size);
- } else {
- (*size)++;
- return true;
- }
-}
-
-bool MiniDisassembler::ProcessSib(unsigned char* start_byte,
- unsigned char mod,
- unsigned int* size) {
- // get the mod field from the 2..0 bits of the SIB byte
- unsigned char sib_base = (*start_byte) & 0x07;
- if (0x05 == sib_base) {
- switch (mod) {
- case 0x00: // mod == 00
- case 0x02: // mod == 10
- operand_bytes_ += OS_DOUBLE_WORD;
- break;
- case 0x01: // mod == 01
- operand_bytes_ += OS_BYTE;
- break;
- case 0x03: // mod == 11
- // According to the IA-32 docs, there does not seem to be a disp
- // value for this value of mod
- default:
- break;
- }
- }
-
- (*size)++;
- return true;
-}
-
-}; // namespace sidestep
generated by cgit v1.1 at 2025-04-02 04:23:57 +0000