mirror of https://github.com/x64dbg/zydis
Fixed mandatory prefixes, added prefix compatibility checks
This commit is contained in:
Joel Höner
parent
cb98db80ea
commit
1faec66a66
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@ -77,12 +77,41 @@ typedef struct ZydisEncoderTableEntry_
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uint8_t operandCount;
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ZydisEncoderTableOperand operands[5];
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ZydisOpcodeMap map;
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ZydisInstructionAttributes mandatoryAttribs;
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ZydisInstructionAttributes attribs;
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ZydisModRMMod modRmMod;
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ZydisModeConstraint modeConstraint;
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ZydisPrefixBit prefixBits;
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uint8_t mandatoryPrefix; // 0x00 = None
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} ZydisEncoderTableEntry;
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struct ZydisPrefixAcceptMapping
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{
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uint64_t has;
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uint64_t accepts;
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} static const prefixAcceptMap[] =
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{
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{ ZYDIS_ATTRIB_HAS_LOCK, ZYDIS_ATTRIB_ACCEPTS_LOCK },
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{ ZYDIS_ATTRIB_HAS_REP, ZYDIS_ATTRIB_ACCEPTS_REP },
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{ ZYDIS_ATTRIB_HAS_REPE, ZYDIS_ATTRIB_ACCEPTS_REPE },
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{ ZYDIS_ATTRIB_HAS_REPZ, ZYDIS_ATTRIB_ACCEPTS_REPZ },
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{ ZYDIS_ATTRIB_HAS_REPNE, ZYDIS_ATTRIB_ACCEPTS_REPNE },
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{ ZYDIS_ATTRIB_HAS_REPNZ, ZYDIS_ATTRIB_ACCEPTS_REPNZ },
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{ ZYDIS_ATTRIB_HAS_BOUND, ZYDIS_ATTRIB_ACCEPTS_BOUND },
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{ ZYDIS_ATTRIB_HAS_XACQUIRE, ZYDIS_ATTRIB_ACCEPTS_XACQUIRE },
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{ ZYDIS_ATTRIB_HAS_XRELEASE, ZYDIS_ATTRIB_ACCEPTS_XRELEASE },
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{ ZYDIS_ATTRIB_HAS_BRANCH_NOT_TAKEN, ZYDIS_ATTRIB_ACCEPTS_BRANCH_HINTS },
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{ ZYDIS_ATTRIB_HAS_BRANCH_TAKEN, ZYDIS_ATTRIB_ACCEPTS_BRANCH_HINTS },
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{ ZYDIS_ATTRIB_HAS_SEGMENT, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
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{ ZYDIS_ATTRIB_HAS_SEGMENT_CS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
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{ ZYDIS_ATTRIB_HAS_SEGMENT_SS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
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{ ZYDIS_ATTRIB_HAS_SEGMENT_DS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
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{ ZYDIS_ATTRIB_HAS_SEGMENT_ES, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
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{ ZYDIS_ATTRIB_HAS_SEGMENT_FS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
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{ ZYDIS_ATTRIB_HAS_SEGMENT_GS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
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{ ZYDIS_ATTRIB_HAS_OPERANDSIZE, ZYDIS_ATTRIB_ACCEPTS_OPERANDSIZE },
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{ ZYDIS_ATTRIB_HAS_ADDRESSSIZE, ZYDIS_ATTRIB_ACCEPTS_ADDRESSSIZE },
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};
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#include <Zydis/Internal/EncoderTable.inc>
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/**
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@ -95,6 +124,8 @@ typedef struct ZydisEncoderContext_
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size_t writeOffs;
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ZydisInstructionInfo* info;
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const ZydisEncoderTableEntry* matchingEntry;
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ZydisBool shouldEmitMandatoryPrefix;
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uint8_t mandatoryPrefix;
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uint8_t dispBitSize;
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uint64_t disp;
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uint8_t immBitSizes[2];
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@ -219,9 +250,9 @@ static ZydisStatus ZydisEmitVEX(ZydisEncoderContext* ctx)
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ZYDIS_ASSERT(ctx);
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// Can we use short 2-byte VEX encoding?
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if (ctx->info->details.vex.X == 1 &&
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ctx->info->details.vex.B == 1 &&
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ctx->info->details.vex.W == 0 &&
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if (ctx->info->details.vex.X == 1 &&
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ctx->info->details.vex.B == 1 &&
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ctx->info->details.vex.W == 0 &&
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ctx->info->details.vex.m_mmmm == 1)
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{
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ZYDIS_CHECK(ZydisEmitByte(ctx, 0xC5));
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@ -424,7 +455,6 @@ static ZydisStatus ZydisPrepareRegOperand(ZydisEncoderContext* ctx,
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ZydisRegister reg, char topBitLoc)
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{
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int16_t regID = ZydisRegisterGetId(reg);
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//ZydisRegisterClass clazz = ZydisRegisterGetClass(reg);
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if (regID == -1) return ZYDIS_STATUS_INVALID_PARAMETER;
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uint8_t lowerBits = (regID & 0x07) >> 0;
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@ -779,6 +809,42 @@ static ZydisStatus ZydisPrepareOperand(ZydisEncoderContext* ctx,
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return ZYDIS_STATUS_SUCCESS;
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}
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static ZydisStatus ZydisPrepareMandatoryPrefixes(ZydisEncoderContext* ctx)
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{
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// Is a prefix mandatory? 0x00 is a sentinel value for `None` in the table.
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if (ctx->matchingEntry->mandatoryPrefix != 0x00)
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{
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uint8_t bitCompressedPrefix = 0x00;
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switch (ctx->matchingEntry->mandatoryPrefix)
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{
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case 0x66: bitCompressedPrefix = 0x01; break;
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case 0xF3: bitCompressedPrefix = 0x02; break;
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case 0xF2: bitCompressedPrefix = 0x03; break;
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default: ZYDIS_UNREACHABLE;
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}
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switch (ctx->info->encoding)
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{
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case ZYDIS_INSTRUCTION_ENCODING_DEFAULT:
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case ZYDIS_INSTRUCTION_ENCODING_3DNOW:
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ctx->shouldEmitMandatoryPrefix = ZYDIS_TRUE;
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ctx->mandatoryPrefix = ctx->matchingEntry->mandatoryPrefix;
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break;
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case ZYDIS_INSTRUCTION_ENCODING_VEX:
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ctx->info->details.vex.pp = bitCompressedPrefix;
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break;
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case ZYDIS_INSTRUCTION_ENCODING_EVEX:
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ctx->info->details.evex.pp = bitCompressedPrefix;
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break;
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case ZYDIS_INSTRUCTION_ENCODING_XOP:
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ctx->info->details.xop.pp = bitCompressedPrefix;
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break;
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}
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}
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return ZYDIS_STATUS_SUCCESS;
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}
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static ZydisStatus ZydisDeriveEncodingForOp(ZydisOperandDefinition* operand)
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{
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switch (operand->type)
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@ -863,9 +929,20 @@ ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t* bufferLen,
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// encoded, what prefixes are required, etc.
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ZYDIS_CHECK(ZydisFindMatchingDef(info, &ctx.matchingEntry));
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info->opcode = ctx.matchingEntry->opcode;
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info->attributes |= ctx.matchingEntry->mandatoryAttribs;
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// TODO: Check compatibility of requested prefixes to found instruction.
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// Check compatibility of requested prefixes to found instruction.
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if (ctx.info->attributes)
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{
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for (size_t i = 0; i < ZYDIS_ARRAY_SIZE(prefixAcceptMap); ++i)
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{
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if (ctx.info->attributes & prefixAcceptMap[i].has &&
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!(ctx.matchingEntry->attribs & prefixAcceptMap[i].accepts))
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{
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// TODO: Better status.
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return ZYDIS_STATUS_IMPOSSIBLE_INSTRUCTION;
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}
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}
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}
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// Determine required prefixes.
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switch (ctx.matchingEntry->encoding)
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@ -887,6 +964,7 @@ ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t* bufferLen,
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info->details.evex.L2 = (pb & ZYDIS_PREFBIT_EVEX_L2) ? 1 : 0;
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info->details.vex.L = (pb & ZYDIS_PREFBIT_VEX_L ) ? 1 : 0;
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info->details.rex.W = (pb & ZYDIS_PREFBIT_REX_W ) ? 1 : 0;
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ZYDIS_CHECK(ZydisPrepareMandatoryPrefixes(&ctx));
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// Prepare opcode.
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ZYDIS_CHECK(ZydisPrepareOpcode(&ctx));
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@ -912,6 +990,8 @@ ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t* bufferLen,
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if (info->attributes & ZYDIS_ATTRIB_HAS_VEX ) ZYDIS_CHECK(ZydisEmitVEX (&ctx));
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if (info->attributes & ZYDIS_ATTRIB_HAS_EVEX ) ZYDIS_CHECK(ZydisEmitEVEX (&ctx));
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if (info->attributes & ZYDIS_ATTRIB_HAS_XOP ) ZYDIS_CHECK(ZydisEmitXOP (&ctx));
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if (ctx.shouldEmitMandatoryPrefix) ZYDIS_CHECK(ZydisEmitByte(&ctx, ctx.mandatoryPrefix));
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for (uint8_t i = 0; i < ctx.opcodeMapPrefixLen; ++i)
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{
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