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Diffstat (limited to 'lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp')
| -rw-r--r-- | lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp | 1838 |
1 files changed, 1838 insertions, 0 deletions
diff --git a/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp new file mode 100644 index 0000000..804606d --- /dev/null +++ b/lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp @@ -0,0 +1,1838 @@ +//===-- X86DisassemblerDecoder.c - Disassembler decoder -------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file is part of the X86 Disassembler. +// It contains the implementation of the instruction decoder. +// Documentation for the disassembler can be found in X86Disassembler.h. +// +//===----------------------------------------------------------------------===// + +#include <stdarg.h> /* for va_*() */ +#include <stdio.h> /* for vsnprintf() */ +#include <stdlib.h> /* for exit() */ +#include <string.h> /* for memset() */ + +#include "X86DisassemblerDecoder.h" + +using namespace llvm::X86Disassembler; + +/// Specifies whether a ModR/M byte is needed and (if so) which +/// instruction each possible value of the ModR/M byte corresponds to. Once +/// this information is known, we have narrowed down to a single instruction. +struct ModRMDecision { + uint8_t modrm_type; + uint16_t instructionIDs; +}; + +/// Specifies which set of ModR/M->instruction tables to look at +/// given a particular opcode. +struct OpcodeDecision { + ModRMDecision modRMDecisions[256]; +}; + +/// Specifies which opcode->instruction tables to look at given +/// a particular context (set of attributes). Since there are many possible +/// contexts, the decoder first uses CONTEXTS_SYM to determine which context +/// applies given a specific set of attributes. Hence there are only IC_max +/// entries in this table, rather than 2^(ATTR_max). +struct ContextDecision { + OpcodeDecision opcodeDecisions[IC_max]; +}; + +#include "X86GenDisassemblerTables.inc" + +#ifndef NDEBUG +#define debug(s) do { Debug(__FILE__, __LINE__, s); } while (0) +#else +#define debug(s) do { } while (0) +#endif + + +/* + * contextForAttrs - Client for the instruction context table. Takes a set of + * attributes and returns the appropriate decode context. + * + * @param attrMask - Attributes, from the enumeration attributeBits. + * @return - The InstructionContext to use when looking up an + * an instruction with these attributes. + */ +static InstructionContext contextForAttrs(uint16_t attrMask) { + return static_cast<InstructionContext>(CONTEXTS_SYM[attrMask]); +} + +/* + * modRMRequired - Reads the appropriate instruction table to determine whether + * the ModR/M byte is required to decode a particular instruction. + * + * @param type - The opcode type (i.e., how many bytes it has). + * @param insnContext - The context for the instruction, as returned by + * contextForAttrs. + * @param opcode - The last byte of the instruction's opcode, not counting + * ModR/M extensions and escapes. + * @return - true if the ModR/M byte is required, false otherwise. + */ +static int modRMRequired(OpcodeType type, + InstructionContext insnContext, + uint16_t opcode) { + const struct ContextDecision* decision = nullptr; + + switch (type) { + case ONEBYTE: + decision = &ONEBYTE_SYM; + break; + case TWOBYTE: + decision = &TWOBYTE_SYM; + break; + case THREEBYTE_38: + decision = &THREEBYTE38_SYM; + break; + case THREEBYTE_3A: + decision = &THREEBYTE3A_SYM; + break; + case XOP8_MAP: + decision = &XOP8_MAP_SYM; + break; + case XOP9_MAP: + decision = &XOP9_MAP_SYM; + break; + case XOPA_MAP: + decision = &XOPA_MAP_SYM; + break; + } + + return decision->opcodeDecisions[insnContext].modRMDecisions[opcode]. + modrm_type != MODRM_ONEENTRY; +} + +/* + * decode - Reads the appropriate instruction table to obtain the unique ID of + * an instruction. + * + * @param type - See modRMRequired(). + * @param insnContext - See modRMRequired(). + * @param opcode - See modRMRequired(). + * @param modRM - The ModR/M byte if required, or any value if not. + * @return - The UID of the instruction, or 0 on failure. + */ +static InstrUID decode(OpcodeType type, + InstructionContext insnContext, + uint8_t opcode, + uint8_t modRM) { + const struct ModRMDecision* dec = nullptr; + + switch (type) { + case ONEBYTE: + dec = &ONEBYTE_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode]; + break; + case TWOBYTE: + dec = &TWOBYTE_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode]; + break; + case THREEBYTE_38: + dec = &THREEBYTE38_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode]; + break; + case THREEBYTE_3A: + dec = &THREEBYTE3A_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode]; + break; + case XOP8_MAP: + dec = &XOP8_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode]; + break; + case XOP9_MAP: + dec = &XOP9_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode]; + break; + case XOPA_MAP: + dec = &XOPA_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode]; + break; + } + + switch (dec->modrm_type) { + default: + debug("Corrupt table! Unknown modrm_type"); + return 0; + case MODRM_ONEENTRY: + return modRMTable[dec->instructionIDs]; + case MODRM_SPLITRM: + if (modFromModRM(modRM) == 0x3) + return modRMTable[dec->instructionIDs+1]; + return modRMTable[dec->instructionIDs]; + case MODRM_SPLITREG: + if (modFromModRM(modRM) == 0x3) + return modRMTable[dec->instructionIDs+((modRM & 0x38) >> 3)+8]; + return modRMTable[dec->instructionIDs+((modRM & 0x38) >> 3)]; + case MODRM_SPLITMISC: + if (modFromModRM(modRM) == 0x3) + return modRMTable[dec->instructionIDs+(modRM & 0x3f)+8]; + return modRMTable[dec->instructionIDs+((modRM & 0x38) >> 3)]; + case MODRM_FULL: + return modRMTable[dec->instructionIDs+modRM]; + } +} + +/* + * specifierForUID - Given a UID, returns the name and operand specification for + * that instruction. + * + * @param uid - The unique ID for the instruction. This should be returned by + * decode(); specifierForUID will not check bounds. + * @return - A pointer to the specification for that instruction. + */ +static const struct InstructionSpecifier *specifierForUID(InstrUID uid) { + return &INSTRUCTIONS_SYM[uid]; +} + +/* + * consumeByte - Uses the reader function provided by the user to consume one + * byte from the instruction's memory and advance the cursor. + * + * @param insn - The instruction with the reader function to use. The cursor + * for this instruction is advanced. + * @param byte - A pointer to a pre-allocated memory buffer to be populated + * with the data read. + * @return - 0 if the read was successful; nonzero otherwise. + */ +static int consumeByte(struct InternalInstruction* insn, uint8_t* byte) { + int ret = insn->reader(insn->readerArg, byte, insn->readerCursor); + + if (!ret) + ++(insn->readerCursor); + + return ret; +} + +/* + * lookAtByte - Like consumeByte, but does not advance the cursor. + * + * @param insn - See consumeByte(). + * @param byte - See consumeByte(). + * @return - See consumeByte(). + */ +static int lookAtByte(struct InternalInstruction* insn, uint8_t* byte) { + return insn->reader(insn->readerArg, byte, insn->readerCursor); +} + +static void unconsumeByte(struct InternalInstruction* insn) { + insn->readerCursor--; +} + +#define CONSUME_FUNC(name, type) \ + static int name(struct InternalInstruction* insn, type* ptr) { \ + type combined = 0; \ + unsigned offset; \ + for (offset = 0; offset < sizeof(type); ++offset) { \ + uint8_t byte; \ + int ret = insn->reader(insn->readerArg, \ + &byte, \ + insn->readerCursor + offset); \ + if (ret) \ + return ret; \ + combined = combined | ((uint64_t)byte << (offset * 8)); \ + } \ + *ptr = combined; \ + insn->readerCursor += sizeof(type); \ + return 0; \ + } + +/* + * consume* - Use the reader function provided by the user to consume data + * values of various sizes from the instruction's memory and advance the + * cursor appropriately. These readers perform endian conversion. + * + * @param insn - See consumeByte(). + * @param ptr - A pointer to a pre-allocated memory of appropriate size to + * be populated with the data read. + * @return - See consumeByte(). + */ +CONSUME_FUNC(consumeInt8, int8_t) +CONSUME_FUNC(consumeInt16, int16_t) +CONSUME_FUNC(consumeInt32, int32_t) +CONSUME_FUNC(consumeUInt16, uint16_t) +CONSUME_FUNC(consumeUInt32, uint32_t) +CONSUME_FUNC(consumeUInt64, uint64_t) + +/* + * dbgprintf - Uses the logging function provided by the user to log a single + * message, typically without a carriage-return. + * + * @param insn - The instruction containing the logging function. + * @param format - See printf(). + * @param ... - See printf(). + */ +static void dbgprintf(struct InternalInstruction* insn, + const char* format, + ...) { + char buffer[256]; + va_list ap; + + if (!insn->dlog) + return; + + va_start(ap, format); + (void)vsnprintf(buffer, sizeof(buffer), format, ap); + va_end(ap); + + insn->dlog(insn->dlogArg, buffer); + + return; +} + +/* + * setPrefixPresent - Marks that a particular prefix is present at a particular + * location. + * + * @param insn - The instruction to be marked as having the prefix. + * @param prefix - The prefix that is present. + * @param location - The location where the prefix is located (in the address + * space of the instruction's reader). + */ +static void setPrefixPresent(struct InternalInstruction* insn, + uint8_t prefix, + uint64_t location) +{ + insn->prefixPresent[prefix] = 1; + insn->prefixLocations[prefix] = location; +} + +/* + * isPrefixAtLocation - Queries an instruction to determine whether a prefix is + * present at a given location. + * + * @param insn - The instruction to be queried. + * @param prefix - The prefix. + * @param location - The location to query. + * @return - Whether the prefix is at that location. + */ +static bool isPrefixAtLocation(struct InternalInstruction* insn, + uint8_t prefix, + uint64_t location) +{ + if (insn->prefixPresent[prefix] == 1 && + insn->prefixLocations[prefix] == location) + return true; + else + return false; +} + +/* + * readPrefixes - Consumes all of an instruction's prefix bytes, and marks the + * instruction as having them. Also sets the instruction's default operand, + * address, and other relevant data sizes to report operands correctly. + * + * @param insn - The instruction whose prefixes are to be read. + * @return - 0 if the instruction could be read until the end of the prefix + * bytes, and no prefixes conflicted; nonzero otherwise. + */ +static int readPrefixes(struct InternalInstruction* insn) { + bool isPrefix = true; + bool prefixGroups[4] = { false }; + uint64_t prefixLocation; + uint8_t byte = 0; + uint8_t nextByte; + + bool hasAdSize = false; + bool hasOpSize = false; + + dbgprintf(insn, "readPrefixes()"); + + while (isPrefix) { + prefixLocation = insn->readerCursor; + + /* If we fail reading prefixes, just stop here and let the opcode reader deal with it */ + if (consumeByte(insn, &byte)) + break; + + /* + * If the byte is a LOCK/REP/REPNE prefix and not a part of the opcode, then + * break and let it be disassembled as a normal "instruction". + */ + if (insn->readerCursor - 1 == insn->startLocation && byte == 0xf0) + break; + + if (insn->readerCursor - 1 == insn->startLocation + && (byte == 0xf2 || byte == 0xf3) + && !lookAtByte(insn, &nextByte)) + { + /* + * If the byte is 0xf2 or 0xf3, and any of the following conditions are + * met: + * - it is followed by a LOCK (0xf0) prefix + * - it is followed by an xchg instruction + * then it should be disassembled as a xacquire/xrelease not repne/rep. + */ + if ((byte == 0xf2 || byte == 0xf3) && + ((nextByte == 0xf0) | + ((nextByte & 0xfe) == 0x86 || (nextByte & 0xf8) == 0x90))) + insn->xAcquireRelease = true; + /* + * Also if the byte is 0xf3, and the following condition is met: + * - it is followed by a "mov mem, reg" (opcode 0x88/0x89) or + * "mov mem, imm" (opcode 0xc6/0xc7) instructions. + * then it should be disassembled as an xrelease not rep. + */ + if (byte == 0xf3 && + (nextByte == 0x88 || nextByte == 0x89 || + nextByte == 0xc6 || nextByte == 0xc7)) + insn->xAcquireRelease = true; + if (insn->mode == MODE_64BIT && (nextByte & 0xf0) == 0x40) { + if (consumeByte(insn, &nextByte)) + return -1; + if (lookAtByte(insn, &nextByte)) + return -1; + unconsumeByte(insn); + } + if (nextByte != 0x0f && nextByte != 0x90) + break; + } + + switch (byte) { + case 0xf0: /* LOCK */ + case 0xf2: /* REPNE/REPNZ */ + case 0xf3: /* REP or REPE/REPZ */ + if (prefixGroups[0]) + dbgprintf(insn, "Redundant Group 1 prefix"); + prefixGroups[0] = true; + setPrefixPresent(insn, byte, prefixLocation); + break; + case 0x2e: /* CS segment override -OR- Branch not taken */ + case 0x36: /* SS segment override -OR- Branch taken */ + case 0x3e: /* DS segment override */ + case 0x26: /* ES segment override */ + case 0x64: /* FS segment override */ + case 0x65: /* GS segment override */ + switch (byte) { + case 0x2e: + insn->segmentOverride = SEG_OVERRIDE_CS; + break; + case 0x36: + insn->segmentOverride = SEG_OVERRIDE_SS; + break; + case 0x3e: + insn->segmentOverride = SEG_OVERRIDE_DS; + break; + case 0x26: + insn->segmentOverride = SEG_OVERRIDE_ES; + break; + case 0x64: + insn->segmentOverride = SEG_OVERRIDE_FS; + break; + case 0x65: + insn->segmentOverride = SEG_OVERRIDE_GS; + break; + default: + debug("Unhandled override"); + return -1; + } + if (prefixGroups[1]) + dbgprintf(insn, "Redundant Group 2 prefix"); + prefixGroups[1] = true; + setPrefixPresent(insn, byte, prefixLocation); + break; + case 0x66: /* Operand-size override */ + if (prefixGroups[2]) + dbgprintf(insn, "Redundant Group 3 prefix"); + prefixGroups[2] = true; + hasOpSize = true; + setPrefixPresent(insn, byte, prefixLocation); + break; + case 0x67: /* Address-size override */ + if (prefixGroups[3]) + dbgprintf(insn, "Redundant Group 4 prefix"); + prefixGroups[3] = true; + hasAdSize = true; + setPrefixPresent(insn, byte, prefixLocation); + break; + default: /* Not a prefix byte */ + isPrefix = false; + break; + } + + if (isPrefix) + dbgprintf(insn, "Found prefix 0x%hhx", byte); + } + + insn->vectorExtensionType = TYPE_NO_VEX_XOP; + + if (byte == 0x62) { + uint8_t byte1, byte2; + + if (consumeByte(insn, &byte1)) { + dbgprintf(insn, "Couldn't read second byte of EVEX prefix"); + return -1; + } + + if (lookAtByte(insn, &byte2)) { + dbgprintf(insn, "Couldn't read third byte of EVEX prefix"); + return -1; + } + + if ((insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0) && + ((~byte1 & 0xc) == 0xc) && ((byte2 & 0x4) == 0x4)) { + insn->vectorExtensionType = TYPE_EVEX; + } + else { + unconsumeByte(insn); /* unconsume byte1 */ + unconsumeByte(insn); /* unconsume byte */ + insn->necessaryPrefixLocation = insn->readerCursor - 2; + } + + if (insn->vectorExtensionType == TYPE_EVEX) { + insn->vectorExtensionPrefix[0] = byte; + insn->vectorExtensionPrefix[1] = byte1; + if (consumeByte(insn, &insn->vectorExtensionPrefix[2])) { + dbgprintf(insn, "Couldn't read third byte of EVEX prefix"); + return -1; + } + if (consumeByte(insn, &insn->vectorExtensionPrefix[3])) { + dbgprintf(insn, "Couldn't read fourth byte of EVEX prefix"); + return -1; + } + + /* We simulate the REX prefix for simplicity's sake */ + if (insn->mode == MODE_64BIT) { + insn->rexPrefix = 0x40 + | (wFromEVEX3of4(insn->vectorExtensionPrefix[2]) << 3) + | (rFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 2) + | (xFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 1) + | (bFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 0); + } + + dbgprintf(insn, "Found EVEX prefix 0x%hhx 0x%hhx 0x%hhx 0x%hhx", + insn->vectorExtensionPrefix[0], insn->vectorExtensionPrefix[1], + insn->vectorExtensionPrefix[2], insn->vectorExtensionPrefix[3]); + } + } + else if (byte == 0xc4) { + uint8_t byte1; + + if (lookAtByte(insn, &byte1)) { + dbgprintf(insn, "Couldn't read second byte of VEX"); + return -1; + } + + if (insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0) { + insn->vectorExtensionType = TYPE_VEX_3B; + insn->necessaryPrefixLocation = insn->readerCursor - 1; + } + else { + unconsumeByte(insn); + insn->necessaryPrefixLocation = insn->readerCursor - 1; + } + + if (insn->vectorExtensionType == TYPE_VEX_3B) { + insn->vectorExtensionPrefix[0] = byte; + consumeByte(insn, &insn->vectorExtensionPrefix[1]); + consumeByte(insn, &insn->vectorExtensionPrefix[2]); + + /* We simulate the REX prefix for simplicity's sake */ + + if (insn->mode == MODE_64BIT) { + insn->rexPrefix = 0x40 + | (wFromVEX3of3(insn->vectorExtensionPrefix[2]) << 3) + | (rFromVEX2of3(insn->vectorExtensionPrefix[1]) << 2) + | (xFromVEX2of3(insn->vectorExtensionPrefix[1]) << 1) + | (bFromVEX2of3(insn->vectorExtensionPrefix[1]) << 0); + } + + dbgprintf(insn, "Found VEX prefix 0x%hhx 0x%hhx 0x%hhx", + insn->vectorExtensionPrefix[0], insn->vectorExtensionPrefix[1], + insn->vectorExtensionPrefix[2]); + } + } + else if (byte == 0xc5) { + uint8_t byte1; + + if (lookAtByte(insn, &byte1)) { + dbgprintf(insn, "Couldn't read second byte of VEX"); + return -1; + } + + if (insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0) { + insn->vectorExtensionType = TYPE_VEX_2B; + } + else { + unconsumeByte(insn); + } + + if (insn->vectorExtensionType == TYPE_VEX_2B) { + insn->vectorExtensionPrefix[0] = byte; + consumeByte(insn, &insn->vectorExtensionPrefix[1]); + + if (insn->mode == MODE_64BIT) { + insn->rexPrefix = 0x40 + | (rFromVEX2of2(insn->vectorExtensionPrefix[1]) << 2); + } + + switch (ppFromVEX2of2(insn->vectorExtensionPrefix[1])) + { + default: + break; + case VEX_PREFIX_66: + hasOpSize = true; + break; + } + + dbgprintf(insn, "Found VEX prefix 0x%hhx 0x%hhx", + insn->vectorExtensionPrefix[0], + insn->vectorExtensionPrefix[1]); + } + } + else if (byte == 0x8f) { + uint8_t byte1; + + if (lookAtByte(insn, &byte1)) { + dbgprintf(insn, "Couldn't read second byte of XOP"); + return -1; + } + + if ((byte1 & 0x38) != 0x0) { /* 0 in these 3 bits is a POP instruction. */ + insn->vectorExtensionType = TYPE_XOP; + insn->necessaryPrefixLocation = insn->readerCursor - 1; + } + else { + unconsumeByte(insn); + insn->necessaryPrefixLocation = insn->readerCursor - 1; + } + + if (insn->vectorExtensionType == TYPE_XOP) { + insn->vectorExtensionPrefix[0] = byte; + consumeByte(insn, &insn->vectorExtensionPrefix[1]); + consumeByte(insn, &insn->vectorExtensionPrefix[2]); + + /* We simulate the REX prefix for simplicity's sake */ + + if (insn->mode == MODE_64BIT) { + insn->rexPrefix = 0x40 + | (wFromXOP3of3(insn->vectorExtensionPrefix[2]) << 3) + | (rFromXOP2of3(insn->vectorExtensionPrefix[1]) << 2) + | (xFromXOP2of3(insn->vectorExtensionPrefix[1]) << 1) + | (bFromXOP2of3(insn->vectorExtensionPrefix[1]) << 0); + } + + switch (ppFromXOP3of3(insn->vectorExtensionPrefix[2])) + { + default: + break; + case VEX_PREFIX_66: + hasOpSize = true; + break; + } + + dbgprintf(insn, "Found XOP prefix 0x%hhx 0x%hhx 0x%hhx", + insn->vectorExtensionPrefix[0], insn->vectorExtensionPrefix[1], + insn->vectorExtensionPrefix[2]); + } + } + else { + if (insn->mode == MODE_64BIT) { + if ((byte & 0xf0) == 0x40) { + uint8_t opcodeByte; + + if (lookAtByte(insn, &opcodeByte) || ((opcodeByte & 0xf0) == 0x40)) { + dbgprintf(insn, "Redundant REX prefix"); + return -1; + } + + insn->rexPrefix = byte; + insn->necessaryPrefixLocation = insn->readerCursor - 2; + + dbgprintf(insn, "Found REX prefix 0x%hhx", byte); + } else { + unconsumeByte(insn); + insn->necessaryPrefixLocation = insn->readerCursor - 1; + } + } else { + unconsumeByte(insn); + insn->necessaryPrefixLocation = insn->readerCursor - 1; + } + } + + if (insn->mode == MODE_16BIT) { + insn->registerSize = (hasOpSize ? 4 : 2); + insn->addressSize = (hasAdSize ? 4 : 2); + insn->displacementSize = (hasAdSize ? 4 : 2); + insn->immediateSize = (hasOpSize ? 4 : 2); + } else if (insn->mode == MODE_32BIT) { + insn->registerSize = (hasOpSize ? 2 : 4); + insn->addressSize = (hasAdSize ? 2 : 4); + insn->displacementSize = (hasAdSize ? 2 : 4); + insn->immediateSize = (hasOpSize ? 2 : 4); + } else if (insn->mode == MODE_64BIT) { + if (insn->rexPrefix && wFromREX(insn->rexPrefix)) { + insn->registerSize = 8; + insn->addressSize = (hasAdSize ? 4 : 8); + insn->displacementSize = 4; + insn->immediateSize = 4; + } else if (insn->rexPrefix) { + insn->registerSize = (hasOpSize ? 2 : 4); + insn->addressSize = (hasAdSize ? 4 : 8); + insn->displacementSize = (hasOpSize ? 2 : 4); + insn->immediateSize = (hasOpSize ? 2 : 4); + } else { + insn->registerSize = (hasOpSize ? 2 : 4); + insn->addressSize = (hasAdSize ? 4 : 8); + insn->displacementSize = (hasOpSize ? 2 : 4); + insn->immediateSize = (hasOpSize ? 2 : 4); + } + } + + return 0; +} + +/* + * readOpcode - Reads the opcode (excepting the ModR/M byte in the case of + * extended or escape opcodes). + * + * @param insn - The instruction whose opcode is to be read. + * @return - 0 if the opcode could be read successfully; nonzero otherwise. + */ +static int readOpcode(struct InternalInstruction* insn) { + /* Determine the length of the primary opcode */ + + uint8_t current; + + dbgprintf(insn, "readOpcode()"); + + insn->opcodeType = ONEBYTE; + + if (insn->vectorExtensionType == TYPE_EVEX) + { + switch (mmFromEVEX2of4(insn->vectorExtensionPrefix[1])) { + default: + dbgprintf(insn, "Unhandled mm field for instruction (0x%hhx)", + mmFromEVEX2of4(insn->vectorExtensionPrefix[1])); + return -1; + case VEX_LOB_0F: + insn->opcodeType = TWOBYTE; + return consumeByte(insn, &insn->opcode); + case VEX_LOB_0F38: + insn->opcodeType = THREEBYTE_38; + return consumeByte(insn, &insn->opcode); + case VEX_LOB_0F3A: + insn->opcodeType = THREEBYTE_3A; + return consumeByte(insn, &insn->opcode); + } + } + else if (insn->vectorExtensionType == TYPE_VEX_3B) { + switch (mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1])) { + default: + dbgprintf(insn, "Unhandled m-mmmm field for instruction (0x%hhx)", + mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1])); + return -1; + case VEX_LOB_0F: + insn->opcodeType = TWOBYTE; + return consumeByte(insn, &insn->opcode); + case VEX_LOB_0F38: + insn->opcodeType = THREEBYTE_38; + return consumeByte(insn, &insn->opcode); + case VEX_LOB_0F3A: + insn->opcodeType = THREEBYTE_3A; + return consumeByte(insn, &insn->opcode); + } + } + else if (insn->vectorExtensionType == TYPE_VEX_2B) { + insn->opcodeType = TWOBYTE; + return consumeByte(insn, &insn->opcode); + } + else if (insn->vectorExtensionType == TYPE_XOP) { + switch (mmmmmFromXOP2of3(insn->vectorExtensionPrefix[1])) { + default: + dbgprintf(insn, "Unhandled m-mmmm field for instruction (0x%hhx)", + mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1])); + return -1; + case XOP_MAP_SELECT_8: + insn->opcodeType = XOP8_MAP; + return consumeByte(insn, &insn->opcode); + case XOP_MAP_SELECT_9: + insn->opcodeType = XOP9_MAP; + return consumeByte(insn, &insn->opcode); + case XOP_MAP_SELECT_A: + insn->opcodeType = XOPA_MAP; + return consumeByte(insn, &insn->opcode); + } + } + + if (consumeByte(insn, ¤t)) + return -1; + + if (current == 0x0f) { + dbgprintf(insn, "Found a two-byte escape prefix (0x%hhx)", current); + + if (consumeByte(insn, ¤t)) + return -1; + + if (current == 0x38) { + dbgprintf(insn, "Found a three-byte escape prefix (0x%hhx)", current); + + if (consumeByte(insn, ¤t)) + return -1; + + insn->opcodeType = THREEBYTE_38; + } else if (current == 0x3a) { + dbgprintf(insn, "Found a three-byte escape prefix (0x%hhx)", current); + + if (consumeByte(insn, ¤t)) + return -1; + + insn->opcodeType = THREEBYTE_3A; + } else { + dbgprintf(insn, "Didn't find a three-byte escape prefix"); + + insn->opcodeType = TWOBYTE; + } + } + + /* + * At this point we have consumed the full opcode. + * Anything we consume from here on must be unconsumed. + */ + + insn->opcode = current; + + return 0; +} + +static int readModRM(struct InternalInstruction* insn); + +/* + * getIDWithAttrMask - Determines the ID of an instruction, consuming + * the ModR/M byte as appropriate for extended and escape opcodes, + * and using a supplied attribute mask. + * + * @param instructionID - A pointer whose target is filled in with the ID of the + * instruction. + * @param insn - The instruction whose ID is to be determined. + * @param attrMask - The attribute mask to search. + * @return - 0 if the ModR/M could be read when needed or was not + * needed; nonzero otherwise. + */ +static int getIDWithAttrMask(uint16_t* instructionID, + struct InternalInstruction* insn, + uint16_t attrMask) { + bool hasModRMExtension; + + InstructionContext instructionClass = contextForAttrs(attrMask); + + hasModRMExtension = modRMRequired(insn->opcodeType, + instructionClass, + insn->opcode); + + if (hasModRMExtension) { + if (readModRM(insn)) + return -1; + + *instructionID = decode(insn->opcodeType, + instructionClass, + insn->opcode, + insn->modRM); + } else { + *instructionID = decode(insn->opcodeType, + instructionClass, + insn->opcode, + 0); + } + + return 0; +} + +/* + * is16BitEquivalent - Determines whether two instruction names refer to + * equivalent instructions but one is 16-bit whereas the other is not. + * + * @param orig - The instruction that is not 16-bit + * @param equiv - The instruction that is 16-bit + */ +static bool is16BitEquivalent(const char* orig, const char* equiv) { + off_t i; + + for (i = 0;; i++) { + if (orig[i] == '\0' && equiv[i] == '\0') + return true; + if (orig[i] == '\0' || equiv[i] == '\0') + return false; + if (orig[i] != equiv[i]) { + if ((orig[i] == 'Q' || orig[i] == 'L') && equiv[i] == 'W') + continue; + if ((orig[i] == '6' || orig[i] == '3') && equiv[i] == '1') + continue; + if ((orig[i] == '4' || orig[i] == '2') && equiv[i] == '6') + continue; + return false; + } + } +} + +/* + * getID - Determines the ID of an instruction, consuming the ModR/M byte as + * appropriate for extended and escape opcodes. Determines the attributes and + * context for the instruction before doing so. + * + * @param insn - The instruction whose ID is to be determined. + * @return - 0 if the ModR/M could be read when needed or was not needed; + * nonzero otherwise. + */ +static int getID(struct InternalInstruction* insn, const void *miiArg) { + uint16_t attrMask; + uint16_t instructionID; + + dbgprintf(insn, "getID()"); + + attrMask = ATTR_NONE; + + if (insn->mode == MODE_64BIT) + attrMask |= ATTR_64BIT; + + if (insn->vectorExtensionType != TYPE_NO_VEX_XOP) { + attrMask |= (insn->vectorExtensionType == TYPE_EVEX) ? ATTR_EVEX : ATTR_VEX; + + if (insn->vectorExtensionType == TYPE_EVEX) { + switch (ppFromEVEX3of4(insn->vectorExtensionPrefix[2])) { + case VEX_PREFIX_66: + attrMask |= ATTR_OPSIZE; + break; + case VEX_PREFIX_F3: + attrMask |= ATTR_XS; + break; + case VEX_PREFIX_F2: + attrMask |= ATTR_XD; + break; + } + + if (zFromEVEX4of4(insn->vectorExtensionPrefix[3])) + attrMask |= ATTR_EVEXKZ; + if (bFromEVEX4of4(insn->vectorExtensionPrefix[3])) + attrMask |= ATTR_EVEXB; + if (aaaFromEVEX4of4(insn->vectorExtensionPrefix[3])) + attrMask |= ATTR_EVEXK; + if (lFromEVEX4of4(insn->vectorExtensionPrefix[3])) + attrMask |= ATTR_EVEXL; + if (l2FromEVEX4of4(insn->vectorExtensionPrefix[3])) + attrMask |= ATTR_EVEXL2; + } + else if (insn->vectorExtensionType == TYPE_VEX_3B) { + switch (ppFromVEX3of3(insn->vectorExtensionPrefix[2])) { + case VEX_PREFIX_66: + attrMask |= ATTR_OPSIZE; + break; + case VEX_PREFIX_F3: + attrMask |= ATTR_XS; + break; + case VEX_PREFIX_F2: + attrMask |= ATTR_XD; + break; + } + + if (lFromVEX3of3(insn->vectorExtensionPrefix[2])) + attrMask |= ATTR_VEXL; + } + else if (insn->vectorExtensionType == TYPE_VEX_2B) { + switch (ppFromVEX2of2(insn->vectorExtensionPrefix[1])) { + case VEX_PREFIX_66: + attrMask |= ATTR_OPSIZE; + break; + case VEX_PREFIX_F3: + attrMask |= ATTR_XS; + break; + case VEX_PREFIX_F2: + attrMask |= ATTR_XD; + break; + } + + if (lFromVEX2of2(insn->vectorExtensionPrefix[1])) + attrMask |= ATTR_VEXL; + } + else if (insn->vectorExtensionType == TYPE_XOP) { + switch (ppFromXOP3of3(insn->vectorExtensionPrefix[2])) { + case VEX_PREFIX_66: + attrMask |= ATTR_OPSIZE; + break; + case VEX_PREFIX_F3: + attrMask |= ATTR_XS; + break; + case VEX_PREFIX_F2: + attrMask |= ATTR_XD; + break; + } + + if (lFromXOP3of3(insn->vectorExtensionPrefix[2])) + attrMask |= ATTR_VEXL; + } + else { + return -1; + } + } + else { + if (insn->mode != MODE_16BIT && isPrefixAtLocation(insn, 0x66, insn->necessaryPrefixLocation)) + attrMask |= ATTR_OPSIZE; + else if (isPrefixAtLocation(insn, 0x67, insn->necessaryPrefixLocation)) + attrMask |= ATTR_ADSIZE; + else if (isPrefixAtLocation(insn, 0xf3, insn->necessaryPrefixLocation)) + attrMask |= ATTR_XS; + else if (isPrefixAtLocation(insn, 0xf2, insn->necessaryPrefixLocation)) + attrMask |= ATTR_XD; + } + + if (insn->rexPrefix & 0x08) + attrMask |= ATTR_REXW; + + if (getIDWithAttrMask(&instructionID, insn, attrMask)) + return -1; + + /* + * JCXZ/JECXZ need special handling for 16-bit mode because the meaning + * of the AdSize prefix is inverted w.r.t. 32-bit mode. + */ + if (insn->mode == MODE_16BIT && insn->opcode == 0xE3) { + const struct InstructionSpecifier *spec; + spec = specifierForUID(instructionID); + + /* + * Check for Ii8PCRel instructions. We could alternatively do a + * string-compare on the names, but this is probably cheaper. + */ + if (x86OperandSets[spec->operands][0].type == TYPE_REL8) { + attrMask ^= ATTR_ADSIZE; + if (getIDWithAttrMask(&instructionID, insn, attrMask)) + return -1; + } + } + + /* The following clauses compensate for limitations of the tables. */ + + if ((insn->mode == MODE_16BIT || insn->prefixPresent[0x66]) && + !(attrMask & ATTR_OPSIZE)) { + /* + * The instruction tables make no distinction between instructions that + * allow OpSize anywhere (i.e., 16-bit operations) and that need it in a + * particular spot (i.e., many MMX operations). In general we're + * conservative, but in the specific case where OpSize is present but not + * in the right place we check if there's a 16-bit operation. + */ + + const struct InstructionSpecifier *spec; + uint16_t instructionIDWithOpsize; + const char *specName, *specWithOpSizeName; + + spec = specifierForUID(instructionID); + + if (getIDWithAttrMask(&instructionIDWithOpsize, + insn, + attrMask | ATTR_OPSIZE)) { + /* + * ModRM required with OpSize but not present; give up and return version + * without OpSize set + */ + + insn->instructionID = instructionID; + insn->spec = spec; + return 0; + } + + specName = GetInstrName(instructionID, miiArg); + specWithOpSizeName = GetInstrName(instructionIDWithOpsize, miiArg); + + if (is16BitEquivalent(specName, specWithOpSizeName) && + (insn->mode == MODE_16BIT) ^ insn->prefixPresent[0x66]) { + insn->instructionID = instructionIDWithOpsize; + insn->spec = specifierForUID(instructionIDWithOpsize); + } else { + insn->instructionID = instructionID; + insn->spec = spec; + } + return 0; + } + + if (insn->opcodeType == ONEBYTE && insn->opcode == 0x90 && + insn->rexPrefix & 0x01) { + /* + * NOOP shouldn't decode as NOOP if REX.b is set. Instead + * it should decode as XCHG %r8, %eax. + */ + + const struct InstructionSpecifier *spec; + uint16_t instructionIDWithNewOpcode; + const struct InstructionSpecifier *specWithNewOpcode; + + spec = specifierForUID(instructionID); + + /* Borrow opcode from one of the other XCHGar opcodes */ + insn->opcode = 0x91; + + if (getIDWithAttrMask(&instructionIDWithNewOpcode, + insn, + attrMask)) { + insn->opcode = 0x90; + + insn->instructionID = instructionID; + insn->spec = spec; + return 0; + } + + specWithNewOpcode = specifierForUID(instructionIDWithNewOpcode); + + /* Change back */ + insn->opcode = 0x90; + + insn->instructionID = instructionIDWithNewOpcode; + insn->spec = specWithNewOpcode; + + return 0; + } + + insn->instructionID = instructionID; + insn->spec = specifierForUID(insn->instructionID); + + return 0; +} + +/* + * readSIB - Consumes the SIB byte to determine addressing information for an + * instruction. + * + * @param insn - The instruction whose SIB byte is to be read. + * @return - 0 if the SIB byte was successfully read; nonzero otherwise. + */ +static int readSIB(struct InternalInstruction* insn) { + SIBIndex sibIndexBase = SIB_INDEX_NONE; + SIBBase sibBaseBase = SIB_BASE_NONE; + uint8_t index, base; + + dbgprintf(insn, "readSIB()"); + + if (insn->consumedSIB) + return 0; + + insn->consumedSIB = true; + + switch (insn->addressSize) { + case 2: + dbgprintf(insn, "SIB-based addressing doesn't work in 16-bit mode"); + return -1; + case 4: + sibIndexBase = SIB_INDEX_EAX; + sibBaseBase = SIB_BASE_EAX; + break; + case 8: + sibIndexBase = SIB_INDEX_RAX; + sibBaseBase = SIB_BASE_RAX; + break; + } + + if (consumeByte(insn, &insn->sib)) + return -1; + + index = indexFromSIB(insn->sib) | (xFromREX(insn->rexPrefix) << 3); + if (insn->vectorExtensionType == TYPE_EVEX) + index |= v2FromEVEX4of4(insn->vectorExtensionPrefix[3]) << 4; + + switch (index) { + case 0x4: + insn->sibIndex = SIB_INDEX_NONE; + break; + default: + insn->sibIndex = (SIBIndex)(sibIndexBase + index); + if (insn->sibIndex == SIB_INDEX_sib || + insn->sibIndex == SIB_INDEX_sib64) + insn->sibIndex = SIB_INDEX_NONE; + break; + } + + switch (scaleFromSIB(insn->sib)) { + case 0: + insn->sibScale = 1; + break; + case 1: + insn->sibScale = 2; + break; + case 2: + insn->sibScale = 4; + break; + case 3: + insn->sibScale = 8; + break; + } + + base = baseFromSIB(insn->sib) | (bFromREX(insn->rexPrefix) << 3); + + switch (base) { + case 0x5: + case 0xd: + switch (modFromModRM(insn->modRM)) { + case 0x0: + insn->eaDisplacement = EA_DISP_32; + insn->sibBase = SIB_BASE_NONE; + break; + case 0x1: + insn->eaDisplacement = EA_DISP_8; + insn->sibBase = (SIBBase)(sibBaseBase + base); + break; + case 0x2: + insn->eaDisplacement = EA_DISP_32; + insn->sibBase = (SIBBase)(sibBaseBase + base); + break; + case 0x3: + debug("Cannot have Mod = 0b11 and a SIB byte"); + return -1; + } + break; + default: + insn->sibBase = (SIBBase)(sibBaseBase + base); + break; + } + + return 0; +} + +/* + * readDisplacement - Consumes the displacement of an instruction. + * + * @param insn - The instruction whose displacement is to be read. + * @return - 0 if the displacement byte was successfully read; nonzero + * otherwise. + */ +static int readDisplacement(struct InternalInstruction* insn) { + int8_t d8; + int16_t d16; + int32_t d32; + + dbgprintf(insn, "readDisplacement()"); + + if (insn->consumedDisplacement) + return 0; + + insn->consumedDisplacement = true; + insn->displacementOffset = insn->readerCursor - insn->startLocation; + + switch (insn->eaDisplacement) { + case EA_DISP_NONE: + insn->consumedDisplacement = false; + break; + case EA_DISP_8: + if (consumeInt8(insn, &d8)) + return -1; + insn->displacement = d8; + break; + case EA_DISP_16: + if (consumeInt16(insn, &d16)) + return -1; + insn->displacement = d16; + break; + case EA_DISP_32: + if (consumeInt32(insn, &d32)) + return -1; + insn->displacement = d32; + break; + } + + insn->consumedDisplacement = true; + return 0; +} + +/* + * readModRM - Consumes all addressing information (ModR/M byte, SIB byte, and + * displacement) for an instruction and interprets it. + * + * @param insn - The instruction whose addressing information is to be read. + * @return - 0 if the information was successfully read; nonzero otherwise. + */ +static int readModRM(struct InternalInstruction* insn) { + uint8_t mod, rm, reg; + + dbgprintf(insn, "readModRM()"); + + if (insn->consumedModRM) + return 0; + + if (consumeByte(insn, &insn->modRM)) + return -1; + insn->consumedModRM = true; + + mod = modFromModRM(insn->modRM); + rm = rmFromModRM(insn->modRM); + reg = regFromModRM(insn->modRM); + + /* + * This goes by insn->registerSize to pick the correct register, which messes + * up if we're using (say) XMM or 8-bit register operands. That gets fixed in + * fixupReg(). + */ + switch (insn->registerSize) { + case 2: + insn->regBase = MODRM_REG_AX; + insn->eaRegBase = EA_REG_AX; + break; + case 4: + insn->regBase = MODRM_REG_EAX; + insn->eaRegBase = EA_REG_EAX; + break; + case 8: + insn->regBase = MODRM_REG_RAX; + insn->eaRegBase = EA_REG_RAX; + break; + } + + reg |= rFromREX(insn->rexPrefix) << 3; + rm |= bFromREX(insn->rexPrefix) << 3; + if (insn->vectorExtensionType == TYPE_EVEX) { + reg |= r2FromEVEX2of4(insn->vectorExtensionPrefix[1]) << 4; + rm |= xFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 4; + } + + insn->reg = (Reg)(insn->regBase + reg); + + switch (insn->addressSize) { + case 2: + insn->eaBaseBase = EA_BASE_BX_SI; + + switch (mod) { + case 0x0: + if (rm == 0x6) { + insn->eaBase = EA_BASE_NONE; + insn->eaDisplacement = EA_DISP_16; + if (readDisplacement(insn)) + return -1; + } else { + insn->eaBase = (EABase)(insn->eaBaseBase + rm); + insn->eaDisplacement = EA_DISP_NONE; + } + break; + case 0x1: + insn->eaBase = (EABase)(insn->eaBaseBase + rm); + insn->eaDisplacement = EA_DISP_8; + insn->displacementSize = 1; + if (readDisplacement(insn)) + return -1; + break; + case 0x2: + insn->eaBase = (EABase)(insn->eaBaseBase + rm); + insn->eaDisplacement = EA_DISP_16; + if (readDisplacement(insn)) + return -1; + break; + case 0x3: + insn->eaBase = (EABase)(insn->eaRegBase + rm); + if (readDisplacement(insn)) + return -1; + break; + } + break; + case 4: + case 8: + insn->eaBaseBase = (insn->addressSize == 4 ? EA_BASE_EAX : EA_BASE_RAX); + + switch (mod) { + case 0x0: + insn->eaDisplacement = EA_DISP_NONE; /* readSIB may override this */ + switch (rm) { + case 0x14: + case 0x4: + case 0xc: /* in case REXW.b is set */ + insn->eaBase = (insn->addressSize == 4 ? + EA_BASE_sib : EA_BASE_sib64); + if (readSIB(insn) || readDisplacement(insn)) + return -1; + break; + case 0x5: + insn->eaBase = EA_BASE_NONE; + insn->eaDisplacement = EA_DISP_32; + if (readDisplacement(insn)) + return -1; + break; + default: + insn->eaBase = (EABase)(insn->eaBaseBase + rm); + break; + } + break; + case 0x1: + insn->displacementSize = 1; + /* FALLTHROUGH */ + case 0x2: + insn->eaDisplacement = (mod == 0x1 ? EA_DISP_8 : EA_DISP_32); + switch (rm) { + case 0x14: + case 0x4: + case 0xc: /* in case REXW.b is set */ + insn->eaBase = EA_BASE_sib; + if (readSIB(insn) || readDisplacement(insn)) + return -1; + break; + default: + insn->eaBase = (EABase)(insn->eaBaseBase + rm); + if (readDisplacement(insn)) + return -1; + break; + } + break; + case 0x3: + insn->eaDisplacement = EA_DISP_NONE; + insn->eaBase = (EABase)(insn->eaRegBase + rm); + break; + } + break; + } /* switch (insn->addressSize) */ + + return 0; +} + +#define GENERIC_FIXUP_FUNC(name, base, prefix) \ + static uint8_t name(struct InternalInstruction *insn, \ + OperandType type, \ + uint8_t index, \ + uint8_t *valid) { \ + *valid = 1; \ + switch (type) { \ + default: \ + debug("Unhandled register type"); \ + *valid = 0; \ + return 0; \ + case TYPE_Rv: \ + return base + index; \ + case TYPE_R8: \ + if (insn->rexPrefix && \ + index >= 4 && index <= 7) { \ + return prefix##_SPL + (index - 4); \ + } else { \ + return prefix##_AL + index; \ + } \ + case TYPE_R16: \ + return prefix##_AX + index; \ + case TYPE_R32: \ + return prefix##_EAX + index; \ + case TYPE_R64: \ + return prefix##_RAX + index; \ + case TYPE_XMM512: \ + return prefix##_ZMM0 + index; \ + case TYPE_XMM256: \ + return prefix##_YMM0 + index; \ + case TYPE_XMM128: \ + case TYPE_XMM64: \ + case TYPE_XMM32: \ + case TYPE_XMM: \ + return prefix##_XMM0 + index; \ + case TYPE_VK1: \ + case TYPE_VK8: \ + case TYPE_VK16: \ + return prefix##_K0 + index; \ + case TYPE_MM64: \ + case TYPE_MM32: \ + case TYPE_MM: \ + if (index > 7) \ + *valid = 0; \ + return prefix##_MM0 + index; \ + case TYPE_SEGMENTREG: \ + if (index > 5) \ + *valid = 0; \ + return prefix##_ES + index; \ + case TYPE_DEBUGREG: \ + if (index > 7) \ + *valid = 0; \ + return prefix##_DR0 + index; \ + case TYPE_CONTROLREG: \ + if (index > 8) \ + *valid = 0; \ + return prefix##_CR0 + index; \ + } \ + } + +/* + * fixup*Value - Consults an operand type to determine the meaning of the + * reg or R/M field. If the operand is an XMM operand, for example, an + * operand would be XMM0 instead of AX, which readModRM() would otherwise + * misinterpret it as. + * + * @param insn - The instruction containing the operand. + * @param type - The operand type. + * @param index - The existing value of the field as reported by readModRM(). + * @param valid - The address of a uint8_t. The target is set to 1 if the + * field is valid for the register class; 0 if not. + * @return - The proper value. + */ +GENERIC_FIXUP_FUNC(fixupRegValue, insn->regBase, MODRM_REG) +GENERIC_FIXUP_FUNC(fixupRMValue, insn->eaRegBase, EA_REG) + +/* + * fixupReg - Consults an operand specifier to determine which of the + * fixup*Value functions to use in correcting readModRM()'ss interpretation. + * + * @param insn - See fixup*Value(). + * @param op - The operand specifier. + * @return - 0 if fixup was successful; -1 if the register returned was + * invalid for its class. + */ +static int fixupReg(struct InternalInstruction *insn, + const struct OperandSpecifier *op) { + uint8_t valid; + + dbgprintf(insn, "fixupReg()"); + + switch ((OperandEncoding)op->encoding) { + default: + debug("Expected a REG or R/M encoding in fixupReg"); + return -1; + case ENCODING_VVVV: + insn->vvvv = (Reg)fixupRegValue(insn, + (OperandType)op->type, + insn->vvvv, + &valid); + if (!valid) + return -1; + break; + case ENCODING_REG: + insn->reg = (Reg)fixupRegValue(insn, + (OperandType)op->type, + insn->reg - insn->regBase, + &valid); + if (!valid) + return -1; + break; + case ENCODING_RM: + if (insn->eaBase >= insn->eaRegBase) { + insn->eaBase = (EABase)fixupRMValue(insn, + (OperandType)op->type, + insn->eaBase - insn->eaRegBase, + &valid); + if (!valid) + return -1; + } + break; + } + + return 0; +} + +/* + * readOpcodeRegister - Reads an operand from the opcode field of an + * instruction and interprets it appropriately given the operand width. + * Handles AddRegFrm instructions. + * + * @param insn - the instruction whose opcode field is to be read. + * @param size - The width (in bytes) of the register being specified. + * 1 means AL and friends, 2 means AX, 4 means EAX, and 8 means + * RAX. + * @return - 0 on success; nonzero otherwise. + */ +static int readOpcodeRegister(struct InternalInstruction* insn, uint8_t size) { + dbgprintf(insn, "readOpcodeRegister()"); + + if (size == 0) + size = insn->registerSize; + + switch (size) { + case 1: + insn->opcodeRegister = (Reg)(MODRM_REG_AL + ((bFromREX(insn->rexPrefix) << 3) + | (insn->opcode & 7))); + if (insn->rexPrefix && + insn->opcodeRegister >= MODRM_REG_AL + 0x4 && + insn->opcodeRegister < MODRM_REG_AL + 0x8) { + insn->opcodeRegister = (Reg)(MODRM_REG_SPL + + (insn->opcodeRegister - MODRM_REG_AL - 4)); + } + + break; + case 2: + insn->opcodeRegister = (Reg)(MODRM_REG_AX + + ((bFromREX(insn->rexPrefix) << 3) + | (insn->opcode & 7))); + break; + case 4: + insn->opcodeRegister = (Reg)(MODRM_REG_EAX + + ((bFromREX(insn->rexPrefix) << 3) + | (insn->opcode & 7))); + break; + case 8: + insn->opcodeRegister = (Reg)(MODRM_REG_RAX + + ((bFromREX(insn->rexPrefix) << 3) + | (insn->opcode & 7))); + break; + } + + return 0; +} + +/* + * readImmediate - Consumes an immediate operand from an instruction, given the + * desired operand size. + * + * @param insn - The instruction whose operand is to be read. + * @param size - The width (in bytes) of the operand. + * @return - 0 if the immediate was successfully consumed; nonzero + * otherwise. + */ +static int readImmediate(struct InternalInstruction* insn, uint8_t size) { + uint8_t imm8; + uint16_t imm16; + uint32_t imm32; + uint64_t imm64; + + dbgprintf(insn, "readImmediate()"); + + if (insn->numImmediatesConsumed == 2) { + debug("Already consumed two immediates"); + return -1; + } + + if (size == 0) + size = insn->immediateSize; + else + insn->immediateSize = size; + insn->immediateOffset = insn->readerCursor - insn->startLocation; + + switch (size) { + case 1: + if (consumeByte(insn, &imm8)) + return -1; + insn->immediates[insn->numImmediatesConsumed] = imm8; + break; + case 2: + if (consumeUInt16(insn, &imm16)) + return -1; + insn->immediates[insn->numImmediatesConsumed] = imm16; + break; + case 4: + if (consumeUInt32(insn, &imm32)) + return -1; + insn->immediates[insn->numImmediatesConsumed] = imm32; + break; + case 8: + if (consumeUInt64(insn, &imm64)) + return -1; + insn->immediates[insn->numImmediatesConsumed] = imm64; + break; + } + + insn->numImmediatesConsumed++; + + return 0; +} + +/* + * readVVVV - Consumes vvvv from an instruction if it has a VEX prefix. + * + * @param insn - The instruction whose operand is to be read. + * @return - 0 if the vvvv was successfully consumed; nonzero + * otherwise. + */ +static int readVVVV(struct InternalInstruction* insn) { + dbgprintf(insn, "readVVVV()"); + + int vvvv; + if (insn->vectorExtensionType == TYPE_EVEX) + vvvv = vvvvFromEVEX3of4(insn->vectorExtensionPrefix[2]); + else if (insn->vectorExtensionType == TYPE_VEX_3B) + vvvv = vvvvFromVEX3of3(insn->vectorExtensionPrefix[2]); + else if (insn->vectorExtensionType == TYPE_VEX_2B) + vvvv = vvvvFromVEX2of2(insn->vectorExtensionPrefix[1]); + else if (insn->vectorExtensionType == TYPE_XOP) + vvvv = vvvvFromXOP3of3(insn->vectorExtensionPrefix[2]); + else + return -1; + + if (insn->mode != MODE_64BIT) + vvvv &= 0x7; + + insn->vvvv = static_cast<Reg>(vvvv); + return 0; +} + +/* + * readMaskRegister - Reads an mask register from the opcode field of an + * instruction. + * + * @param insn - The instruction whose opcode field is to be read. + * @return - 0 on success; nonzero otherwise. + */ +static int readMaskRegister(struct InternalInstruction* insn) { + dbgprintf(insn, "readMaskRegister()"); + + if (insn->vectorExtensionType != TYPE_EVEX) + return -1; + + insn->writemask = + static_cast<Reg>(aaaFromEVEX4of4(insn->vectorExtensionPrefix[3])); + return 0; +} + +/* + * readOperands - Consults the specifier for an instruction and consumes all + * operands for that instruction, interpreting them as it goes. + * + * @param insn - The instruction whose operands are to be read and interpreted. + * @return - 0 if all operands could be read; nonzero otherwise. + */ +static int readOperands(struct InternalInstruction* insn) { + int hasVVVV, needVVVV; + int sawRegImm = 0; + + dbgprintf(insn, "readOperands()"); + + /* If non-zero vvvv specified, need to make sure one of the operands + uses it. */ + hasVVVV = !readVVVV(insn); + needVVVV = hasVVVV && (insn->vvvv != 0); + + for (const auto &Op : x86OperandSets[insn->spec->operands]) { + switch (Op.encoding) { + case ENCODING_NONE: + case ENCODING_SI: + case ENCODING_DI: + break; + case ENCODING_REG: + case ENCODING_RM: + if (readModRM(insn)) + return -1; + if (fixupReg(insn, &Op)) + return -1; + break; + case ENCODING_CB: + case ENCODING_CW: + case ENCODING_CD: + case ENCODING_CP: + case ENCODING_CO: + case ENCODING_CT: + dbgprintf(insn, "We currently don't hande code-offset encodings"); + return -1; + case ENCODING_IB: + if (sawRegImm) { + /* Saw a register immediate so don't read again and instead split the + previous immediate. FIXME: This is a hack. */ + insn->immediates[insn->numImmediatesConsumed] = + insn->immediates[insn->numImmediatesConsumed - 1] & 0xf; + ++insn->numImmediatesConsumed; + break; + } + if (readImmediate(insn, 1)) + return -1; + if (Op.type == TYPE_IMM3 && + insn->immediates[insn->numImmediatesConsumed - 1] > 7) + return -1; + if (Op.type == TYPE_IMM5 && + insn->immediates[insn->numImmediatesConsumed - 1] > 31) + return -1; + if (Op.type == TYPE_XMM128 || + Op.type == TYPE_XMM256) + sawRegImm = 1; + break; + case ENCODING_IW: + if (readImmediate(insn, 2)) + return -1; + break; + case ENCODING_ID: + if (readImmediate(insn, 4)) + return -1; + break; + case ENCODING_IO: + if (readImmediate(insn, 8)) + return -1; + break; + case ENCODING_Iv: + if (readImmediate(insn, insn->immediateSize)) + return -1; + break; + case ENCODING_Ia: + if (readImmediate(insn, insn->addressSize)) + return -1; + break; + case ENCODING_RB: + if (readOpcodeRegister(insn, 1)) + return -1; + break; + case ENCODING_RW: + if (readOpcodeRegister(insn, 2)) + return -1; + break; + case ENCODING_RD: + if (readOpcodeRegister(insn, 4)) + return -1; + break; + case ENCODING_RO: + if (readOpcodeRegister(insn, 8)) + return -1; + break; + case ENCODING_Rv: + if (readOpcodeRegister(insn, 0)) + return -1; + break; + case ENCODING_FP: + break; + case ENCODING_VVVV: + needVVVV = 0; /* Mark that we have found a VVVV operand. */ + if (!hasVVVV) + return -1; + if (fixupReg(insn, &Op)) + return -1; + break; + case ENCODING_WRITEMASK: + if (readMaskRegister(insn)) + return -1; + break; + case ENCODING_DUP: + break; + default: + dbgprintf(insn, "Encountered an operand with an unknown encoding."); + return -1; + } + } + + /* If we didn't find ENCODING_VVVV operand, but non-zero vvvv present, fail */ + if (needVVVV) return -1; + + return 0; +} + +/* + * decodeInstruction - Reads and interprets a full instruction provided by the + * user. + * + * @param insn - A pointer to the instruction to be populated. Must be + * pre-allocated. + * @param reader - The function to be used to read the instruction's bytes. + * @param readerArg - A generic argument to be passed to the reader to store + * any internal state. + * @param logger - If non-NULL, the function to be used to write log messages + * and warnings. + * @param loggerArg - A generic argument to be passed to the logger to store + * any internal state. + * @param startLoc - The address (in the reader's address space) of the first + * byte in the instruction. + * @param mode - The mode (real mode, IA-32e, or IA-32e in 64-bit mode) to + * decode the instruction in. + * @return - 0 if the instruction's memory could be read; nonzero if + * not. + */ +int llvm::X86Disassembler::decodeInstruction( + struct InternalInstruction *insn, byteReader_t reader, + const void *readerArg, dlog_t logger, void *loggerArg, const void *miiArg, + uint64_t startLoc, DisassemblerMode mode) { + memset(insn, 0, sizeof(struct InternalInstruction)); + + insn->reader = reader; + insn->readerArg = readerArg; + insn->dlog = logger; + insn->dlogArg = loggerArg; + insn->startLocation = startLoc; + insn->readerCursor = startLoc; + insn->mode = mode; + insn->numImmediatesConsumed = 0; + + if (readPrefixes(insn) || + readOpcode(insn) || + getID(insn, miiArg) || + insn->instructionID == 0 || + readOperands(insn)) + return -1; + + insn->operands = x86OperandSets[insn->spec->operands]; + + insn->length = insn->readerCursor - insn->startLocation; + + dbgprintf(insn, "Read from 0x%llx to 0x%llx: length %zu", + startLoc, insn->readerCursor, insn->length); + + if (insn->length > 15) + dbgprintf(insn, "Instruction exceeds 15-byte limit"); + + return 0; +} |