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zydis
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Minor encoder cleanup

This commit is contained in:
Joel Höner 2017-01-22 17:38:14 +01:00
parent 587187af89
commit cb98db80ea
3 changed files with 44 additions and 29 deletions
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8
include/Zydis/Encoder.h
View File

@ -52,13 +52,7 @@ extern "C" {
ZYDIS_ATTRIB_HAS_XACQUIRE | \
ZYDIS_ATTRIB_HAS_XRELEASE | \
ZYDIS_ATTRIB_HAS_BRANCH_TAKEN | \
ZYDIS_ATTRIB_HAS_BRANCH_NOT_TAKEN | \
ZYDIS_ATTRIB_HAS_SEGMENT_CS | \
ZYDIS_ATTRIB_HAS_SEGMENT_DS | \
ZYDIS_ATTRIB_HAS_SEGMENT_SS | \
ZYDIS_ATTRIB_HAS_SEGMENT_ES | \
ZYDIS_ATTRIB_HAS_SEGMENT_FS | \
ZYDIS_ATTRIB_HAS_SEGMENT_GS \
ZYDIS_ATTRIB_HAS_BRANCH_NOT_TAKEN \
)
/* ============================================================================================== */

60
src/Encoder.c
View File

@ -31,7 +31,7 @@
#include <stdint.h>
/* ============================================================================================== */
/* Internal context */
/* Internal context and table types */
/* ============================================================================================== */
typedef struct ZydisEncoderTableOperand_
@ -107,26 +107,22 @@ typedef struct ZydisEncoderContext_
/* Internal helpers */
/* ============================================================================================== */
static ZydisStatus ZydisEmitByte(ZydisEncoderContext* ctx, uint8_t byte)
{
if (ctx->writeOffs + 1 >= ctx->bufferLen)
{
return ZYDIS_STATUS_INSUFFICIENT_BUFFER_SIZE;
}
ctx->buffer[ctx->writeOffs++] = byte;
return ZYDIS_STATUS_SUCCESS;
}
/* ---------------------------------------------------------------------------------------------- */
/* Byte stream output functions. Those are the only funcs that access the output stream directly. */
/* ---------------------------------------------------------------------------------------------- */
static ZydisStatus ZydisEmitImm(ZydisEncoderContext* ctx, uint64_t imm, int bits)
{
ZYDIS_ASSERT(bits == 8 || bits == 16 || bits == 32 || bits == 64);
size_t newWriteOffs = ctx->writeOffs + bits / 8;
if (newWriteOffs >= ctx->bufferLen ||
newWriteOffs > ZYDIS_MAX_INSTRUCTION_LENGTH)
if (newWriteOffs >= ctx->bufferLen)
{
return ZYDIS_STATUS_INSUFFICIENT_BUFFER_SIZE;
}
if (newWriteOffs > ZYDIS_MAX_INSTRUCTION_LENGTH)
{
return ZYDIS_STATUS_IMPOSSIBLE_INSTRUCTION; // TODO
}
// TODO: bswap on big-endian
switch (bits)
@ -142,6 +138,15 @@ static ZydisStatus ZydisEmitImm(ZydisEncoderContext* ctx, uint64_t imm, int bits
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisEmitByte(ZydisEncoderContext* ctx, uint8_t byte)
{
return ZydisEmitImm(ctx, byte, 8);
}
/* ---------------------------------------------------------------------------------------------- */
/* Byte code encoding functions. Translate prepared data to final format. */
/* ---------------------------------------------------------------------------------------------- */
static ZydisStatus ZydisEmitLegacyPrefixes(ZydisEncoderContext* ctx)
{
ZYDIS_ASSERT(ctx);
@ -326,6 +331,10 @@ static ZydisStatus ZydisEmitSIB(ZydisEncoderContext* ctx)
return ZYDIS_STATUS_SUCCESS;
}
/* ---------------------------------------------------------------------------------------------- */
/* Preparation functions. Parse encoder request, determine required bytes and prefixes. */
/* ---------------------------------------------------------------------------------------------- */
static ZydisStatus ZydisPrepareOpcode(ZydisEncoderContext* ctx)
{
ZYDIS_ASSERT(ctx);
@ -480,20 +489,26 @@ static ZydisStatus ZydisPrepareRegOperand(ZydisEncoderContext* ctx,
return ZYDIS_STATUS_SUCCESS;
}
static ZydisBool ZydisIsStackReg(ZydisRegister reg)
static ZydisBool ZydisIsBPReg(ZydisRegister reg)
{
return reg == ZYDIS_REGISTER_SP ||
reg == ZYDIS_REGISTER_ESP ||
reg == ZYDIS_REGISTER_RSP ||
return reg == ZYDIS_REGISTER_BPL ||
reg == ZYDIS_REGISTER_BP ||
reg == ZYDIS_REGISTER_EBP ||
reg == ZYDIS_REGISTER_RBP;
}
static ZydisBool ZydisIsStackReg(ZydisRegister reg)
{
return reg == ZYDIS_REGISTER_SPL ||
reg == ZYDIS_REGISTER_SP ||
reg == ZYDIS_REGISTER_ESP ||
reg == ZYDIS_REGISTER_RSP ||
ZydisIsBPReg(reg);
}
static ZydisStatus ZydisPrepareMemoryOperand(ZydisEncoderContext* ctx,
ZydisOperandInfo* operand, const ZydisEncoderTableOperand* tableEntry)
{
// TODO: rBP
// TODO: RIP relative addressing
// Absolute memory access?
@ -625,8 +640,11 @@ static ZydisStatus ZydisPrepareMemoryOperand(ZydisEncoderContext* ctx,
ctx->info->attributes |= ZYDIS_ATTRIB_HAS_SIB;
}
// Has displacement?
if (operand->mem.disp.value.sdword)
// Has displacement or is rBP and we have no SIB?
// rBP can't be ModRM-encoded without a disp.
if (operand->mem.disp.value.sdword ||
(!(ctx->info->attributes & ZYDIS_ATTRIB_HAS_SIB)
&& ZydisIsBPReg(operand->mem.base)))
{
int32_t divisor = 1;
switch (tableEntry->encoding)
@ -817,6 +835,8 @@ static ZydisStatus ZydisFindMatchingDef(const ZydisInstructionInfo* info,
return ZYDIS_STATUS_IMPOSSIBLE_INSTRUCTION;
}
/* ---------------------------------------------------------------------------------------------- */
/* ============================================================================================== */
/* Implementation of public functions */
/* ============================================================================================== */

1
tools/ZydisDisasm.c
View File

@ -106,6 +106,7 @@ int main(int argc, char** argv)
ZydisStatus encStatus = ZydisEncoderEncodeInstruction(
encBuffer, &encBufferSize, &info
);
(void)encStatus;
ZYDIS_ASSERT(ZYDIS_SUCCESS(encStatus));
for (size_t i = 0; i < encBufferSize; ++i)
{