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zydis
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Fixed mandatory prefixes, added prefix compatibility checks

This commit is contained in:
Joel Höner 2017-01-22 19:02:07 +01:00
parent cb98db80ea
commit 1faec66a66
1 changed files with 87 additions and 7 deletions
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94
src/Encoder.c
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@ -77,12 +77,41 @@ typedef struct ZydisEncoderTableEntry_
uint8_t operandCount;
ZydisEncoderTableOperand operands[5];
ZydisOpcodeMap map;
ZydisInstructionAttributes mandatoryAttribs;
ZydisInstructionAttributes attribs;
ZydisModRMMod modRmMod;
ZydisModeConstraint modeConstraint;
ZydisPrefixBit prefixBits;
uint8_t mandatoryPrefix; // 0x00 = None
} ZydisEncoderTableEntry;
struct ZydisPrefixAcceptMapping
{
uint64_t has;
uint64_t accepts;
} static const prefixAcceptMap[] =
{
{ ZYDIS_ATTRIB_HAS_LOCK, ZYDIS_ATTRIB_ACCEPTS_LOCK },
{ ZYDIS_ATTRIB_HAS_REP, ZYDIS_ATTRIB_ACCEPTS_REP },
{ ZYDIS_ATTRIB_HAS_REPE, ZYDIS_ATTRIB_ACCEPTS_REPE },
{ ZYDIS_ATTRIB_HAS_REPZ, ZYDIS_ATTRIB_ACCEPTS_REPZ },
{ ZYDIS_ATTRIB_HAS_REPNE, ZYDIS_ATTRIB_ACCEPTS_REPNE },
{ ZYDIS_ATTRIB_HAS_REPNZ, ZYDIS_ATTRIB_ACCEPTS_REPNZ },
{ ZYDIS_ATTRIB_HAS_BOUND, ZYDIS_ATTRIB_ACCEPTS_BOUND },
{ ZYDIS_ATTRIB_HAS_XACQUIRE, ZYDIS_ATTRIB_ACCEPTS_XACQUIRE },
{ ZYDIS_ATTRIB_HAS_XRELEASE, ZYDIS_ATTRIB_ACCEPTS_XRELEASE },
{ ZYDIS_ATTRIB_HAS_BRANCH_NOT_TAKEN, ZYDIS_ATTRIB_ACCEPTS_BRANCH_HINTS },
{ ZYDIS_ATTRIB_HAS_BRANCH_TAKEN, ZYDIS_ATTRIB_ACCEPTS_BRANCH_HINTS },
{ ZYDIS_ATTRIB_HAS_SEGMENT, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
{ ZYDIS_ATTRIB_HAS_SEGMENT_CS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
{ ZYDIS_ATTRIB_HAS_SEGMENT_SS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
{ ZYDIS_ATTRIB_HAS_SEGMENT_DS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
{ ZYDIS_ATTRIB_HAS_SEGMENT_ES, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
{ ZYDIS_ATTRIB_HAS_SEGMENT_FS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
{ ZYDIS_ATTRIB_HAS_SEGMENT_GS, ZYDIS_ATTRIB_ACCEPTS_SEGMENT },
{ ZYDIS_ATTRIB_HAS_OPERANDSIZE, ZYDIS_ATTRIB_ACCEPTS_OPERANDSIZE },
{ ZYDIS_ATTRIB_HAS_ADDRESSSIZE, ZYDIS_ATTRIB_ACCEPTS_ADDRESSSIZE },
};
#include <Zydis/Internal/EncoderTable.inc>
/**
@ -95,6 +124,8 @@ typedef struct ZydisEncoderContext_
size_t writeOffs;
ZydisInstructionInfo* info;
const ZydisEncoderTableEntry* matchingEntry;
ZydisBool shouldEmitMandatoryPrefix;
uint8_t mandatoryPrefix;
uint8_t dispBitSize;
uint64_t disp;
uint8_t immBitSizes[2];
@ -219,9 +250,9 @@ static ZydisStatus ZydisEmitVEX(ZydisEncoderContext* ctx)
ZYDIS_ASSERT(ctx);
// Can we use short 2-byte VEX encoding?
if (ctx->info->details.vex.X == 1 &&
ctx->info->details.vex.B == 1 &&
ctx->info->details.vex.W == 0 &&
if (ctx->info->details.vex.X == 1 &&
ctx->info->details.vex.B == 1 &&
ctx->info->details.vex.W == 0 &&
ctx->info->details.vex.m_mmmm == 1)
{
ZYDIS_CHECK(ZydisEmitByte(ctx, 0xC5));
@ -424,7 +455,6 @@ static ZydisStatus ZydisPrepareRegOperand(ZydisEncoderContext* ctx,
ZydisRegister reg, char topBitLoc)
{
int16_t regID = ZydisRegisterGetId(reg);
//ZydisRegisterClass clazz = ZydisRegisterGetClass(reg);
if (regID == -1) return ZYDIS_STATUS_INVALID_PARAMETER;
uint8_t lowerBits = (regID & 0x07) >> 0;
@ -779,6 +809,42 @@ static ZydisStatus ZydisPrepareOperand(ZydisEncoderContext* ctx,
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisPrepareMandatoryPrefixes(ZydisEncoderContext* ctx)
{
// Is a prefix mandatory? 0x00 is a sentinel value for `None` in the table.
if (ctx->matchingEntry->mandatoryPrefix != 0x00)
{
uint8_t bitCompressedPrefix = 0x00;
switch (ctx->matchingEntry->mandatoryPrefix)
{
case 0x66: bitCompressedPrefix = 0x01; break;
case 0xF3: bitCompressedPrefix = 0x02; break;
case 0xF2: bitCompressedPrefix = 0x03; break;
default: ZYDIS_UNREACHABLE;
}
switch (ctx->info->encoding)
{
case ZYDIS_INSTRUCTION_ENCODING_DEFAULT:
case ZYDIS_INSTRUCTION_ENCODING_3DNOW:
ctx->shouldEmitMandatoryPrefix = ZYDIS_TRUE;
ctx->mandatoryPrefix = ctx->matchingEntry->mandatoryPrefix;
break;
case ZYDIS_INSTRUCTION_ENCODING_VEX:
ctx->info->details.vex.pp = bitCompressedPrefix;
break;
case ZYDIS_INSTRUCTION_ENCODING_EVEX:
ctx->info->details.evex.pp = bitCompressedPrefix;
break;
case ZYDIS_INSTRUCTION_ENCODING_XOP:
ctx->info->details.xop.pp = bitCompressedPrefix;
break;
}
}
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisDeriveEncodingForOp(ZydisOperandDefinition* operand)
{
switch (operand->type)
@ -863,9 +929,20 @@ ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t* bufferLen,
// encoded, what prefixes are required, etc.
ZYDIS_CHECK(ZydisFindMatchingDef(info, &ctx.matchingEntry));
info->opcode = ctx.matchingEntry->opcode;
info->attributes |= ctx.matchingEntry->mandatoryAttribs;
// TODO: Check compatibility of requested prefixes to found instruction.
// Check compatibility of requested prefixes to found instruction.
if (ctx.info->attributes)
{
for (size_t i = 0; i < ZYDIS_ARRAY_SIZE(prefixAcceptMap); ++i)
{
if (ctx.info->attributes & prefixAcceptMap[i].has &&
!(ctx.matchingEntry->attribs & prefixAcceptMap[i].accepts))
{
// TODO: Better status.
return ZYDIS_STATUS_IMPOSSIBLE_INSTRUCTION;
}
}
}
// Determine required prefixes.
switch (ctx.matchingEntry->encoding)
@ -887,6 +964,7 @@ ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t* bufferLen,
info->details.evex.L2 = (pb & ZYDIS_PREFBIT_EVEX_L2) ? 1 : 0;
info->details.vex.L = (pb & ZYDIS_PREFBIT_VEX_L ) ? 1 : 0;
info->details.rex.W = (pb & ZYDIS_PREFBIT_REX_W ) ? 1 : 0;
ZYDIS_CHECK(ZydisPrepareMandatoryPrefixes(&ctx));
// Prepare opcode.
ZYDIS_CHECK(ZydisPrepareOpcode(&ctx));
@ -913,6 +991,8 @@ ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t* bufferLen,
if (info->attributes & ZYDIS_ATTRIB_HAS_EVEX ) ZYDIS_CHECK(ZydisEmitEVEX (&ctx));
if (info->attributes & ZYDIS_ATTRIB_HAS_XOP ) ZYDIS_CHECK(ZydisEmitXOP (&ctx));
if (ctx.shouldEmitMandatoryPrefix) ZYDIS_CHECK(ZydisEmitByte(&ctx, ctx.mandatoryPrefix));
for (uint8_t i = 0; i < ctx.opcodeMapPrefixLen; ++i)
{
ZYDIS_CHECK(ZydisEmitByte(&ctx, ctx.opcodeMapPrefix[i]));