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zydis
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Added encoding of opcode bits into ModRM

This commit is contained in:
Joel Höner 2017-01-22 22:12:06 +01:00
parent 1faec66a66
commit eb64a23231
1 changed files with 31 additions and 1 deletions
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32
src/Encoder.c
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@ -78,10 +78,11 @@ typedef struct ZydisEncoderTableEntry_
ZydisEncoderTableOperand operands[5];
ZydisOpcodeMap map;
ZydisInstructionAttributes attribs;
ZydisModRMMod modRmMod;
ZydisModRMMod modRmReg;
ZydisModeConstraint modeConstraint;
ZydisPrefixBit prefixBits;
uint8_t mandatoryPrefix; // 0x00 = None
uint8_t modrmReg; // 0xFF = None
} ZydisEncoderTableEntry;
struct ZydisPrefixAcceptMapping
@ -419,6 +420,8 @@ static ZydisStatus ZydisPrepareOpcode(ZydisEncoderContext* ctx)
static ZydisStatus ZydisSimplifyOperandType(ZydisSemanticOperandType semType,
ZydisOperandType* simpleType)
{
ZYDIS_ASSERT(simpleType);
// TODO: Better mapping, this is just for testing.
switch (semType)
{
@ -454,6 +457,8 @@ static ZydisStatus ZydisSimplifyOperandType(ZydisSemanticOperandType semType,
static ZydisStatus ZydisPrepareRegOperand(ZydisEncoderContext* ctx,
ZydisRegister reg, char topBitLoc)
{
ZYDIS_ASSERT(ctx);
int16_t regID = ZydisRegisterGetId(reg);
if (regID == -1) return ZYDIS_STATUS_INVALID_PARAMETER;
@ -539,6 +544,10 @@ static ZydisBool ZydisIsStackReg(ZydisRegister reg)
static ZydisStatus ZydisPrepareMemoryOperand(ZydisEncoderContext* ctx,
ZydisOperandInfo* operand, const ZydisEncoderTableOperand* tableEntry)
{
ZYDIS_ASSERT(ctx);
ZYDIS_ASSERT(operand);
ZYDIS_ASSERT(tableEntry);
// TODO: RIP relative addressing
// Absolute memory access?
@ -727,12 +736,17 @@ static ZydisStatus ZydisPrepareMemoryOperand(ZydisEncoderContext* ctx,
static ZydisStatus ZydisPrepareOperand(ZydisEncoderContext* ctx,
ZydisOperandInfo* operand, const ZydisEncoderTableOperand* tableEntry)
{
ZYDIS_ASSERT(ctx);
ZYDIS_ASSERT(operand);
ZYDIS_ASSERT(tableEntry);
switch (tableEntry->encoding)
{
case ZYDIS_OPERAND_ENCODING_NONE:
break; // Nothing to do.
case ZYDIS_OPERAND_ENCODING_REG:
{
ZYDIS_ASSERT(!ctx->info->details.modrm.reg);
ZYDIS_CHECK(ZydisPrepareRegOperand(ctx, operand->reg, 'R'));
} break;
case ZYDIS_OPERAND_ENCODING_RM:
@ -743,6 +757,12 @@ static ZydisStatus ZydisPrepareOperand(ZydisEncoderContext* ctx,
case ZYDIS_OPERAND_ENCODING_RM_CD32:
case ZYDIS_OPERAND_ENCODING_RM_CD64:
{
ZYDIS_ASSERT(!ctx->info->details.modrm.mod);
ZYDIS_ASSERT(!ctx->info->details.modrm.rm);
ZYDIS_ASSERT(!ctx->info->details.sib.base);
ZYDIS_ASSERT(!ctx->info->details.sib.index);
ZYDIS_ASSERT(!ctx->info->details.sib.scale);
// Memory operand?
if (operand->type == ZYDIS_OPERAND_TYPE_MEMORY)
{
@ -811,6 +831,8 @@ static ZydisStatus ZydisPrepareOperand(ZydisEncoderContext* ctx,
static ZydisStatus ZydisPrepareMandatoryPrefixes(ZydisEncoderContext* ctx)
{
ZYDIS_ASSERT(ctx);
// Is a prefix mandatory? 0x00 is a sentinel value for `None` in the table.
if (ctx->matchingEntry->mandatoryPrefix != 0x00)
{
@ -847,6 +869,8 @@ static ZydisStatus ZydisPrepareMandatoryPrefixes(ZydisEncoderContext* ctx)
static ZydisStatus ZydisDeriveEncodingForOp(ZydisOperandDefinition* operand)
{
ZYDIS_ASSERT(operand);
switch (operand->type)
{
default:
@ -969,6 +993,12 @@ ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t* bufferLen,
// Prepare opcode.
ZYDIS_CHECK(ZydisPrepareOpcode(&ctx));
// Some instructions have additional opcode bits encoded in ModRM.reg.
if (ctx.matchingEntry->modRmReg != 0xFF)
{
ctx.info->details.modrm.reg = ctx.matchingEntry->modRmReg;
}
// Analyze and prepare operands.
if (info->operandCount > ZYDIS_ARRAY_SIZE(info->operands))
{