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zydis
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Fixed register decoding for XOP and VEX instructions

This commit is contained in:
flobernd 2017-06-28 20:46:32 +02:00
parent b118637dae
commit 808ccac372
1 changed files with 22 additions and 13 deletions
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35
src/Decoder.c
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@ -149,19 +149,19 @@ enum ZydisRegisterEncodings
/** /**
* @brief The register-id is encoded in `modrm.reg`. * @brief The register-id is encoded in `modrm.reg`.
* *
* Possible extension by `REX/XOP/VEX/EVEX/MVEX.R'` (vector only) and `REX/XOP/VEX/EVEX/MVEX.R`. * Possible extension by `EVEX/MVEX.R'` (vector only) and `REX/XOP/VEX/EVEX/MVEX.R`.
*/ */
ZYDIS_REG_ENCODING_REG, ZYDIS_REG_ENCODING_REG,
/** /**
* @brief The register-id is encoded in `XOP/VEX/EVEX/MVEX.vvvv`. * @brief The register-id is encoded in `XOP/VEX/EVEX/MVEX.vvvv`.
* *
* Possible extension by `EVEX/MVEX.V'` (vector only). * Possible extension by `EVEX/MVEX.v'` (vector only).
*/ */
ZYDIS_REG_ENCODING_NDSNDD, ZYDIS_REG_ENCODING_NDSNDD,
/** /**
* @brief The register-id is encoded in `modrm.rm`. * @brief The register-id is encoded in `modrm.rm`.
* *
* Possible extension by `REX/XOP/VEX/EVEX/MVEX.X` (vector only) and `REX/XOP/VEX/EVEX/MVEX.B`. * Possible extension by `EVEX/MVEX.X` (vector only) and `REX/XOP/VEX/EVEX/MVEX.B`.
*/ */
ZYDIS_REG_ENCODING_RM, ZYDIS_REG_ENCODING_RM,
/** /**
@ -179,7 +179,7 @@ enum ZydisRegisterEncodings
/** /**
* @brief The register-id is encoded in `sib.index`. * @brief The register-id is encoded in `sib.index`.
* *
* Possible extension by `REX/XOP/VEX/EVEX/MVEX.V'` (vector only) and `REX/XOP/VEX/EVEX/MVEX.X`. * Possible extension by `EVEX/MVEX.V'` (vector only) and `REX/XOP/VEX/EVEX/MVEX.X`.
*/ */
ZYDIS_REG_ENCODING_VIDX, ZYDIS_REG_ENCODING_VIDX,
/** /**
@ -906,11 +906,12 @@ static uint8_t ZydisCalcRegisterId(ZydisDecoderContext* context, ZydisInstructio
{ {
ZYDIS_ASSERT(info->details.modrm.isDecoded); ZYDIS_ASSERT(info->details.modrm.isDecoded);
uint8_t value = info->details.modrm.reg | (context->cache.R << 3); uint8_t value = info->details.modrm.reg | (context->cache.R << 3);
// R' only exists for EVEX and MVEX. No encoding check needed
switch (registerClass) switch (registerClass)
{ {
case ZYDIS_REGCLASS_XMM: case ZYDIS_REGCLASS_XMM:
case ZYDIS_REGCLASS_YMM: case ZYDIS_REGCLASS_YMM:
case ZYDIS_REGCLASS_ZMM: case ZYDIS_REGCLASS_ZMM:
value |= (context->cache.R2 << 4); value |= (context->cache.R2 << 4);
break; break;
default: default:
@ -919,6 +920,7 @@ static uint8_t ZydisCalcRegisterId(ZydisDecoderContext* context, ZydisInstructio
return value; return value;
} }
case ZYDIS_REG_ENCODING_NDSNDD: case ZYDIS_REG_ENCODING_NDSNDD:
// v' only exists for EVEX and MVEX. No encoding check needed
switch (registerClass) switch (registerClass)
{ {
case ZYDIS_REGCLASS_XMM: case ZYDIS_REGCLASS_XMM:
@ -934,15 +936,21 @@ static uint8_t ZydisCalcRegisterId(ZydisDecoderContext* context, ZydisInstructio
{ {
ZYDIS_ASSERT(info->details.modrm.isDecoded); ZYDIS_ASSERT(info->details.modrm.isDecoded);
uint8_t value = info->details.modrm.rm | (context->cache.B << 3); uint8_t value = info->details.modrm.rm | (context->cache.B << 3);
switch (registerClass) // We have to check the instruction-encoding, because the extension by X is only valid
// for EVEX and MVEX instructions
if ((info->encoding == ZYDIS_INSTRUCTION_ENCODING_EVEX) ||
(info->encoding == ZYDIS_INSTRUCTION_ENCODING_MVEX))
{ {
case ZYDIS_REGCLASS_XMM: switch (registerClass)
case ZYDIS_REGCLASS_YMM: {
case ZYDIS_REGCLASS_ZMM: case ZYDIS_REGCLASS_XMM:
value |= (context->cache.X << 4); case ZYDIS_REGCLASS_YMM:
break; case ZYDIS_REGCLASS_ZMM:
default: value |= (context->cache.X << 4);
break; break;
default:
break;
}
} }
return value; return value;
} }
@ -967,6 +975,7 @@ static uint8_t ZydisCalcRegisterId(ZydisDecoderContext* context, ZydisInstructio
ZYDIS_ASSERT((registerClass == ZYDIS_REGCLASS_XMM) || ZYDIS_ASSERT((registerClass == ZYDIS_REGCLASS_XMM) ||
(registerClass == ZYDIS_REGCLASS_YMM) || (registerClass == ZYDIS_REGCLASS_YMM) ||
(registerClass == ZYDIS_REGCLASS_ZMM)); (registerClass == ZYDIS_REGCLASS_ZMM));
// v' only exists for EVEX and MVEX. No encoding check needed
return info->details.sib.index | (context->cache.X << 3) | (context->cache.V2 << 4); return info->details.sib.index | (context->cache.X << 3) | (context->cache.V2 << 4);
case ZYDIS_REG_ENCODING_IS4: case ZYDIS_REG_ENCODING_IS4:
{ {