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zydis
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Implemented basic prefix encoding

This commit is contained in:
Joel Höner 2017-01-12 18:53:28 +01:00
parent 3d2365b6ed
commit 0793090388
2 changed files with 206 additions and 42 deletions
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33
include/Zydis/Encoder.h
View File

@ -36,50 +36,21 @@
extern "C" {
#endif
/* ============================================================================================== */
/* Types */
/* ============================================================================================== */
/**
* @brief Defines the @c ZydisInstructionEncoder struct.
*
* All fields in this struct are private and may change anytime.
*/
typedef struct ZydisInstructionEncoder_
{
/**
* @brief The output buffer.
*/
struct
{
uint8_t* buffer;
size_t bufferLen;
} output;
} ZydisInstructionEncoder;
/* ============================================================================================== */
/* Exported functions */
/* ============================================================================================== */
/**
* @brief Initializes the given @c ZydisInstructionEncoder instance.
* @param decoder A pointer to the @c ZydisInstructionEncoder instance.
* @return A zydis status code.
*/
ZYDIS_EXPORT ZydisStatus ZydisEncoderInitInstructionEncoder(ZydisInstructionEncoder* encoder);
/**
* @brief Encodes the given instruction info to byte-code.
*
* @param encoder A pointer to the @c ZydisInstructionEncoder instance.
* @param buffer A pointer to the output buffer.
* @param bufferLen The length of the output buffer.
* @param info A pointer to the @c ZydisInstructionInfo struct to be encoded.
*
* @return A zydis status code.
*/
ZYDIS_EXPORT ZydisStatus ZydisEncoderEncodeInstruction(ZydisInstructionEncoder* encoder,
const void* buffer, size_t bufferLen, ZydisInstructionInfo* info);
ZYDIS_EXPORT ZydisStatus ZydisEncoderEncodeInstruction(const void* buffer, size_t bufferLen,
ZydisInstructionInfo* info);
/* ============================================================================================== */

217
src/Encoder.c
View File

@ -26,25 +26,218 @@
#include <Zydis/Encoder.h>
/* ============================================================================================== */
/* Internal context */
/* ============================================================================================== */
/**
* @brief The encoder context struct.
*/
typedef struct ZydisInstructionEncoder_
{
uint8_t* buffer;
size_t bufferLen;
size_t writeOffs;
ZydisInstructionInfo* info;
} ZydisInstructionEncoder;
/* ============================================================================================== */
/* Internal helpers */
/* ============================================================================================== */
static ZydisStatus ZydisEmitByte(ZydisInstructionEncoder* encoder, uint8_t byte)
{
if (encoder->writeOffs + 1 >= encoder->bufferLen)
{
return ZYDIS_STATUS_INSUFFICIENT_BUFFER_SIZE;
}
encoder->buffer[encoder->writeOffs++] = byte;
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisEncodeLegacyPrefixes(ZydisInstructionEncoder* encoder)
{
ZYDIS_ASSERT(encoder);
uint64_t attribs = encoder->info->attributes;
if (attribs & ZYDIS_ATTRIB_HAS_LOCK)
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0xF0));
}
if (attribs & (ZYDIS_ATTRIB_HAS_REP | ZYDIS_ATTRIB_HAS_REPE | ZYDIS_ATTRIB_HAS_XRELEASE))
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0xF3));
}
if (attribs & (ZYDIS_ATTRIB_HAS_REPNE | ZYDIS_ATTRIB_HAS_BOUND | ZYDIS_ATTRIB_HAS_XACQUIRE))
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0xF2));
}
if (attribs & (ZYDIS_ATTRIB_HAS_BRANCH_NOT_TAKEN | ZYDIS_ATTRIB_HAS_SEGMENT_CS))
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x2E));
}
if (attribs & (ZYDIS_ATTRIB_HAS_BRANCH_TAKEN | ZYDIS_ATTRIB_HAS_SEGMENT_DS))
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x3E));
}
if (attribs & ZYDIS_ATTRIB_HAS_SEGMENT_SS)
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x36));
}
if (attribs & ZYDIS_ATTRIB_HAS_SEGMENT_ES)
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x26));
}
if (attribs & ZYDIS_ATTRIB_HAS_SEGMENT_FS)
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x64));
}
if (attribs & ZYDIS_ATTRIB_HAS_SEGMENT_GS)
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x65));
}
if (attribs & ZYDIS_ATTRIB_HAS_OPERANDSIZE)
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x66));
}
if (attribs & ZYDIS_ATTRIB_HAS_ADDRESSSIZE)
{
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x67));
}
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisEncodeREX(ZydisInstructionEncoder *encoder)
{
ZYDIS_ASSERT(encoder);
ZYDIS_CHECK(ZydisEmitByte(
encoder,
0x40 |
(encoder->info->details.rex.W & 0x01) << 3 |
(encoder->info->details.rex.R & 0x01) << 2 |
(encoder->info->details.rex.X & 0x01) << 1 |
(encoder->info->details.rex.B & 0x01) << 0
));
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisEncodeVEX(ZydisInstructionEncoder *encoder)
{
ZYDIS_ASSERT(encoder);
// Write opcode.
uint8_t opcode = encoder->info->details.vex.data[0];
ZYDIS_CHECK(ZydisEmitByte(encoder, opcode));
// Write prefix' "operands".
switch (opcode)
{
case 0xC4:
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.vex.R & 0x01) << 7 |
(encoder->info->details.vex.X & 0x01) << 6 |
(encoder->info->details.vex.B & 0x01) << 5 |
(encoder->info->details.vex.m_mmmm & 0x1F) << 0
));
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.vex.W & 0x01) << 7 |
(encoder->info->details.vex.vvvv & 0x0F) << 3 |
(encoder->info->details.vex.L & 0x01) << 2 |
(encoder->info->details.vex.pp & 0x03) << 0
));
break;
case 0xC5:
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.vex.R & 0x01) << 7 |
(encoder->info->details.vex.vvvv & 0x0F) << 3 |
(encoder->info->details.vex.L & 0x01) << 2 |
(encoder->info->details.vex.pp & 0x03) << 0
));
break;
default:
ZYDIS_UNREACHABLE; // TODO: return error instead
}
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisEncodeEVEX(ZydisInstructionEncoder *encoder)
{
ZYDIS_ASSERT(encoder);
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x62));
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.evex.R & 0x01) << 7 |
(encoder->info->details.evex.X & 0x01) << 6 |
(encoder->info->details.evex.B & 0x01) << 5 |
(encoder->info->details.evex.R2 & 0x01) << 4 |
(encoder->info->details.evex.mm & 0x03) << 0
));
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.evex.W & 0x01) << 7 |
(encoder->info->details.evex.vvvv & 0x0F) << 3 |
(encoder->info->details.evex.pp & 0x03) << 0
));
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.evex.z & 0x01) << 7 |
(encoder->info->details.evex.L2 & 0x01) << 6 |
(encoder->info->details.evex.L & 0x01) << 5 |
(encoder->info->details.evex.b & 0x01) << 4 |
(encoder->info->details.evex.V2 & 0x01) << 3 |
(encoder->info->details.evex.aaa & 0x07) << 0
));
return ZYDIS_STATUS_SUCCESS;
}
static ZydisStatus ZydisEncodeXOP(ZydisInstructionEncoder *encoder)
{
ZYDIS_ASSERT(encoder);
ZYDIS_CHECK(ZydisEmitByte(encoder, 0x8F));
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.xop.R & 0x01) << 7 |
(encoder->info->details.xop.X & 0x01) << 6 |
(encoder->info->details.xop.B & 0x01) << 5 |
(encoder->info->details.xop.m_mmmm & 0x1F) << 0
));
ZYDIS_CHECK(ZydisEmitByte(
encoder,
(encoder->info->details.xop.W & 0x01) << 7 |
(encoder->info->details.xop.vvvv & 0x0F) << 3 |
(encoder->info->details.xop.L & 0x01) << 2 |
(encoder->info->details.xop.pp & 0x03) << 0
));
return ZYDIS_STATUS_SUCCESS;
}
/* ============================================================================================== */
/* Implementation of public functions */
/* ============================================================================================== */
ZydisStatus ZydisEncoderInitInstructionEncoder(ZydisInstructionEncoder* encoder)
ZydisStatus ZydisEncoderEncodeInstruction(void* buffer, size_t bufferLen,
ZydisInstructionInfo* info)
{
// Nothing yet.
(void)encoder;
return ZYDIS_STATUS_SUCCESS;
}
ZydisStatus ZydisEncoderEncodeInstruction(ZydisInstructionEncoder* encoder,
void* buffer, size_t bufferLen, ZydisInstructionInfo* info)
{
if (!encoder || !info) return ZYDIS_STATUS_INVALID_PARAMETER;
if (!info) return ZYDIS_STATUS_INVALID_PARAMETER;
if (!buffer || !bufferLen) return ZYDIS_STATUS_INSUFFICIENT_BUFFER_SIZE;
encoder->output.buffer = (uint8_t*)buffer;
encoder->output.bufferLen = bufferLen;
ZydisInstructionEncoder encoder;
encoder.buffer = (uint8_t*)buffer;
encoder.bufferLen = bufferLen;
encoder.writeOffs = 0;
encoder.info = info;
ZYDIS_CHECK(ZydisEncodeLegacyPrefixes(&encoder));
return ZYDIS_STATUS_SUCCESS;
}