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fuchsia / third_party / capstone / refs/heads/upstream/next / . / arch / X86 / X86DisassemblerDecoder.c
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/*===-- X86DisassemblerDecoder.c - Disassembler decoder ------------*- C -*-===*
*
* The LLVM Compiler Infrastructure
*
* This file is distributed under the University of Illinois Open Source
* License. See LICENSE.TXT for details.
*
*===----------------------------------------------------------------------===*
*
* This file is part of the X86 Disassembler.
* It contains the implementation of the instruction decoder.
* Documentation for the disassembler can be found in X86Disassembler.h.
*
*===----------------------------------------------------------------------===*/
/* Capstone Disassembly Engine */
/* By Nguyen Anh Quynh <aquynh@gmail.com>, 2013-2019 */
#ifdef CAPSTONE_HAS_X86
#include <stdarg.h> /* for va_*() */
#if defined(CAPSTONE_HAS_OSXKERNEL)
#include <libkern/libkern.h>
#else
#include <stdlib.h> /* for exit() */
#endif
#include <string.h>
#include "../../cs_priv.h"
#include "../../utils.h"
#include "X86DisassemblerDecoder.h"
#include "X86Mapping.h"
/// Specifies whether a ModR/M byte is needed and (if so) which
/// instruction each possible value of the ModR/M byte corresponds to. Once
/// this information is known, we have narrowed down to a single instruction.
struct ModRMDecision {
uint8_t modrm_type;
uint16_t instructionIDs;
};
/// Specifies which set of ModR/M->instruction tables to look at
/// given a particular opcode.
struct OpcodeDecision {
struct ModRMDecision modRMDecisions[256];
};
/// Specifies which opcode->instruction tables to look at given
/// a particular context (set of attributes). Since there are many possible
/// contexts, the decoder first uses CONTEXTS_SYM to determine which context
/// applies given a specific set of attributes. Hence there are only IC_max
/// entries in this table, rather than 2^(ATTR_max).
struct ContextDecision {
struct OpcodeDecision opcodeDecisions[IC_max];
};
#ifdef CAPSTONE_X86_REDUCE
#include "X86GenDisassemblerTables_reduce.inc"
#include "X86GenDisassemblerTables_reduce2.inc"
#include "X86Lookup16_reduce.inc"
#else
#include "X86GenDisassemblerTables.inc"
#include "X86GenDisassemblerTables2.inc"
#include "X86Lookup16.inc"
#endif
/*
* contextForAttrs - Client for the instruction context table. Takes a set of
* attributes and returns the appropriate decode context.
*
* @param attrMask - Attributes, from the enumeration attributeBits.
* @return - The InstructionContext to use when looking up an
* an instruction with these attributes.
*/
static InstructionContext contextForAttrs(uint16_t attrMask)
{
return CONTEXTS_SYM[attrMask];
}
/*
* modRMRequired - Reads the appropriate instruction table to determine whether
* the ModR/M byte is required to decode a particular instruction.
*
* @param type - The opcode type (i.e., how many bytes it has).
* @param insnContext - The context for the instruction, as returned by
* contextForAttrs.
* @param opcode - The last byte of the instruction's opcode, not counting
* ModR/M extensions and escapes.
* @return - true if the ModR/M byte is required, false otherwise.
*/
static int modRMRequired(OpcodeType type,
InstructionContext insnContext,
uint16_t opcode)
{
const struct OpcodeDecision *decision = NULL;
const uint8_t *indextable = NULL;
unsigned int index;
switch (type) {
default: break;
case ONEBYTE:
decision = ONEBYTE_SYM;
indextable = index_x86DisassemblerOneByteOpcodes;
break;
case TWOBYTE:
decision = TWOBYTE_SYM;
indextable = index_x86DisassemblerTwoByteOpcodes;
break;
case THREEBYTE_38:
decision = THREEBYTE38_SYM;
indextable = index_x86DisassemblerThreeByte38Opcodes;
break;
case THREEBYTE_3A:
decision = THREEBYTE3A_SYM;
indextable = index_x86DisassemblerThreeByte3AOpcodes;
break;
#ifndef CAPSTONE_X86_REDUCE
case XOP8_MAP:
decision = XOP8_MAP_SYM;
indextable = index_x86DisassemblerXOP8Opcodes;
break;
case XOP9_MAP:
decision = XOP9_MAP_SYM;
indextable = index_x86DisassemblerXOP9Opcodes;
break;
case XOPA_MAP:
decision = XOPA_MAP_SYM;
indextable = index_x86DisassemblerXOPAOpcodes;
break;
case THREEDNOW_MAP:
// 3DNow instructions always have ModRM byte
return true;
#endif
}
// return decision->opcodeDecisions[insnContext].modRMDecisions[opcode].modrm_type != MODRM_ONEENTRY;
index = indextable[insnContext];
if (index)
return decision[index - 1].modRMDecisions[opcode].modrm_type != MODRM_ONEENTRY;
else
return false;
}
/*
* decode - Reads the appropriate instruction table to obtain the unique ID of
* an instruction.
*
* @param type - See modRMRequired().
* @param insnContext - See modRMRequired().
* @param opcode - See modRMRequired().
* @param modRM - The ModR/M byte if required, or any value if not.
* @return - The UID of the instruction, or 0 on failure.
*/
static InstrUID decode(OpcodeType type,
InstructionContext insnContext,
uint8_t opcode,
uint8_t modRM)
{
const struct ModRMDecision *dec = NULL;
unsigned int index;
static const struct OpcodeDecision emptyDecision = { 0 };
switch (type) {
default: break; // never reach
case ONEBYTE:
// dec = &ONEBYTE_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86DisassemblerOneByteOpcodes[insnContext];
if (index)
dec = &ONEBYTE_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
case TWOBYTE:
//dec = &TWOBYTE_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86DisassemblerTwoByteOpcodes[insnContext];
if (index)
dec = &TWOBYTE_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
case THREEBYTE_38:
// dec = &THREEBYTE38_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86DisassemblerThreeByte38Opcodes[insnContext];
if (index)
dec = &THREEBYTE38_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
case THREEBYTE_3A:
//dec = &THREEBYTE3A_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86DisassemblerThreeByte3AOpcodes[insnContext];
if (index)
dec = &THREEBYTE3A_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
#ifndef CAPSTONE_X86_REDUCE
case XOP8_MAP:
// dec = &XOP8_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86DisassemblerXOP8Opcodes[insnContext];
if (index)
dec = &XOP8_MAP_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
case XOP9_MAP:
// dec = &XOP9_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86DisassemblerXOP9Opcodes[insnContext];
if (index)
dec = &XOP9_MAP_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
case XOPA_MAP:
// dec = &XOPA_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86DisassemblerXOPAOpcodes[insnContext];
if (index)
dec = &XOPA_MAP_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
case THREEDNOW_MAP:
// dec = &THREEDNOW_MAP_SYM.opcodeDecisions[insnContext].modRMDecisions[opcode];
index = index_x86Disassembler3DNowOpcodes[insnContext];
if (index)
dec = &THREEDNOW_MAP_SYM[index - 1].modRMDecisions[opcode];
else
dec = &emptyDecision.modRMDecisions[opcode];
break;
#endif
}
switch (dec->modrm_type) {
default:
// debug("Corrupt table! Unknown modrm_type");
return 0;
case MODRM_ONEENTRY:
return modRMTable[dec->instructionIDs];
case MODRM_SPLITRM:
if (modFromModRM(modRM) == 0x3)
return modRMTable[dec->instructionIDs + 1];
return modRMTable[dec->instructionIDs];
case MODRM_SPLITREG:
if (modFromModRM(modRM) == 0x3)
return modRMTable[dec->instructionIDs+((modRM & 0x38) >> 3) + 8];
return modRMTable[dec->instructionIDs+((modRM & 0x38) >> 3)];
case MODRM_SPLITMISC:
if (modFromModRM(modRM) == 0x3)
return modRMTable[dec->instructionIDs+(modRM & 0x3f) + 8];
return modRMTable[dec->instructionIDs+((modRM & 0x38) >> 3)];
case MODRM_FULL:
return modRMTable[dec->instructionIDs+modRM];
}
}
/*
* specifierForUID - Given a UID, returns the name and operand specification for
* that instruction.
*
* @param uid - The unique ID for the instruction. This should be returned by
* decode(); specifierForUID will not check bounds.
* @return - A pointer to the specification for that instruction.
*/
static const struct InstructionSpecifier *specifierForUID(InstrUID uid)
{
return &INSTRUCTIONS_SYM[uid];
}
/*
* consumeByte - Uses the reader function provided by the user to consume one
* byte from the instruction's memory and advance the cursor.
*
* @param insn - The instruction with the reader function to use. The cursor
* for this instruction is advanced.
* @param byte - A pointer to a pre-allocated memory buffer to be populated
* with the data read.
* @return - 0 if the read was successful; nonzero otherwise.
*/
static int consumeByte(struct InternalInstruction* insn, uint8_t* byte)
{
int ret = insn->reader(insn->readerArg, byte, insn->readerCursor);
if (!ret)
++(insn->readerCursor);
return ret;
}
/*
* lookAtByte - Like consumeByte, but does not advance the cursor.
*
* @param insn - See consumeByte().
* @param byte - See consumeByte().
* @return - See consumeByte().
*/
static int lookAtByte(struct InternalInstruction* insn, uint8_t* byte)
{
return insn->reader(insn->readerArg, byte, insn->readerCursor);
}
static void unconsumeByte(struct InternalInstruction* insn)
{
insn->readerCursor--;
}
#define CONSUME_FUNC(name, type) \
static int name(struct InternalInstruction* insn, type* ptr) { \
type combined = 0; \
unsigned offset; \
for (offset = 0; offset < sizeof(type); ++offset) { \
uint8_t byte; \
int ret = insn->reader(insn->readerArg, \
&byte, \
insn->readerCursor + offset); \
if (ret) \
return ret; \
combined = combined | ((uint64_t)byte << (offset * 8)); \
} \
*ptr = combined; \
insn->readerCursor += sizeof(type); \
return 0; \
}
/*
* consume* - Use the reader function provided by the user to consume data
* values of various sizes from the instruction's memory and advance the
* cursor appropriately. These readers perform endian conversion.
*
* @param insn - See consumeByte().
* @param ptr - A pointer to a pre-allocated memory of appropriate size to
* be populated with the data read.
* @return - See consumeByte().
*/
CONSUME_FUNC(consumeInt8, int8_t)
CONSUME_FUNC(consumeInt16, int16_t)
CONSUME_FUNC(consumeInt32, int32_t)
CONSUME_FUNC(consumeUInt16, uint16_t)
CONSUME_FUNC(consumeUInt32, uint32_t)
CONSUME_FUNC(consumeUInt64, uint64_t)
static bool isREX(struct InternalInstruction *insn, uint8_t prefix)
{
if (insn->mode == MODE_64BIT)
return prefix >= 0x40 && prefix <= 0x4f;
return false;
}
/*
* setPrefixPresent - Marks that a particular prefix is present as mandatory
*
* @param insn - The instruction to be marked as having the prefix.
* @param prefix - The prefix that is present.
*/
static void setPrefixPresent(struct InternalInstruction *insn, uint8_t prefix)
{
uint8_t nextByte;
switch (prefix) {
case 0xf0: // LOCK
insn->hasLockPrefix = true;
insn->repeatPrefix = 0;
break;
case 0xf2: // REPNE/REPNZ
case 0xf3: // REP or REPE/REPZ
if (lookAtByte(insn, &nextByte))
break;
// TODO:
// 1. There could be several 0x66
// 2. if (nextByte == 0x66) and nextNextByte != 0x0f then
// it's not mandatory prefix
// 3. if (nextByte >= 0x40 && nextByte <= 0x4f) it's REX and we need
// 0x0f exactly after it to be mandatory prefix
if (isREX(insn, nextByte) || nextByte == 0x0f || nextByte == 0x66)
// The last of 0xf2 /0xf3 is mandatory prefix
insn->mandatoryPrefix = prefix;
insn->repeatPrefix = prefix;
insn->hasLockPrefix = false;
break;
case 0x66:
if (lookAtByte(insn, &nextByte))
break;
// 0x66 can't overwrite existing mandatory prefix and should be ignored
if (!insn->mandatoryPrefix && (nextByte == 0x0f || isREX(insn, nextByte)))
insn->mandatoryPrefix = prefix;
break;
}
}
/*
* readPrefixes - Consumes all of an instruction's prefix bytes, and marks the
* instruction as having them. Also sets the instruction's default operand,
* address, and other relevant data sizes to report operands correctly.
*
* @param insn - The instruction whose prefixes are to be read.
* @return - 0 if the instruction could be read until the end of the prefix
* bytes, and no prefixes conflicted; nonzero otherwise.
*/
static int readPrefixes(struct InternalInstruction* insn)
{
bool isPrefix = true;
uint8_t byte = 0;
uint8_t nextByte;
while (isPrefix) {
if (insn->mode == MODE_64BIT) {
// eliminate consecutive redundant REX bytes in front
if (consumeByte(insn, &byte))
return -1;
if ((byte & 0xf0) == 0x40) {
while(true) {
if (lookAtByte(insn, &byte)) // out of input code
return -1;
if ((byte & 0xf0) == 0x40) {
// another REX prefix, but we only remember the last one
if (consumeByte(insn, &byte))
return -1;
} else
break;
}
// recover the last REX byte if next byte is not a legacy prefix
switch (byte) {
case 0xf2: /* REPNE/REPNZ */
case 0xf3: /* REP or REPE/REPZ */
case 0xf0: /* LOCK */
case 0x2e: /* CS segment override -OR- Branch not taken */
case 0x36: /* SS segment override -OR- Branch taken */
case 0x3e: /* DS segment override */
case 0x26: /* ES segment override */
case 0x64: /* FS segment override */
case 0x65: /* GS segment override */
case 0x66: /* Operand-size override */
case 0x67: /* Address-size override */
break;
default: /* Not a prefix byte */
unconsumeByte(insn);
break;
}
} else {
unconsumeByte(insn);
}
}
/* If we fail reading prefixes, just stop here and let the opcode reader deal with it */
if (consumeByte(insn, &byte))
return -1;
if (insn->readerCursor - 1 == insn->startLocation
&& (byte == 0xf2 || byte == 0xf3)) {
// prefix requires next byte
if (lookAtByte(insn, &nextByte))
return -1;
/*
* If the byte is 0xf2 or 0xf3, and any of the following conditions are
* met:
* - it is followed by a LOCK (0xf0) prefix
* - it is followed by an xchg instruction
* then it should be disassembled as a xacquire/xrelease not repne/rep.
*/
if (((nextByte == 0xf0) ||
((nextByte & 0xfe) == 0x86 || (nextByte & 0xf8) == 0x90))) {
insn->xAcquireRelease = byte;
}
/*
* Also if the byte is 0xf3, and the following condition is met:
* - it is followed by a "mov mem, reg" (opcode 0x88/0x89) or
* "mov mem, imm" (opcode 0xc6/0xc7) instructions.
* then it should be disassembled as an xrelease not rep.
*/
if (byte == 0xf3 && (nextByte == 0x88 || nextByte == 0x89 ||
nextByte == 0xc6 || nextByte == 0xc7)) {
insn->xAcquireRelease = byte;
}
if (isREX(insn, nextByte)) {
uint8_t nnextByte;
// Go to REX prefix after the current one
if (consumeByte(insn, &nnextByte))
return -1;
// We should be able to read next byte after REX prefix
if (lookAtByte(insn, &nnextByte))
return -1;
unconsumeByte(insn);
}
}
switch (byte) {
case 0xf0: /* LOCK */
case 0xf2: /* REPNE/REPNZ */
case 0xf3: /* REP or REPE/REPZ */
// only accept the last prefix
setPrefixPresent(insn, byte);
insn->prefix0 = byte;
break;
case 0x2e: /* CS segment override -OR- Branch not taken */
case 0x36: /* SS segment override -OR- Branch taken */
case 0x3e: /* DS segment override */
case 0x26: /* ES segment override */
case 0x64: /* FS segment override */
case 0x65: /* GS segment override */
switch (byte) {
case 0x2e:
insn->segmentOverride = SEG_OVERRIDE_CS;
insn->prefix1 = byte;
break;
case 0x36:
insn->segmentOverride = SEG_OVERRIDE_SS;
insn->prefix1 = byte;
break;
case 0x3e:
insn->segmentOverride = SEG_OVERRIDE_DS;
insn->prefix1 = byte;
break;
case 0x26:
insn->segmentOverride = SEG_OVERRIDE_ES;
insn->prefix1 = byte;
break;
case 0x64:
insn->segmentOverride = SEG_OVERRIDE_FS;
insn->prefix1 = byte;
break;
case 0x65:
insn->segmentOverride = SEG_OVERRIDE_GS;
insn->prefix1 = byte;
break;
default:
// debug("Unhandled override");
return -1;
}
setPrefixPresent(insn, byte);
break;
case 0x66: /* Operand-size override */
insn->hasOpSize = true;
setPrefixPresent(insn, byte);
insn->prefix2 = byte;
break;
case 0x67: /* Address-size override */
insn->hasAdSize = true;
setPrefixPresent(insn, byte);
insn->prefix3 = byte;
break;
default: /* Not a prefix byte */
isPrefix = false;
break;
}
}
insn->vectorExtensionType = TYPE_NO_VEX_XOP;
if (byte == 0x62) {
uint8_t byte1, byte2;
if (consumeByte(insn, &byte1)) {
// dbgprintf(insn, "Couldn't read second byte of EVEX prefix");
return -1;
}
if (lookAtByte(insn, &byte2)) {
// dbgprintf(insn, "Couldn't read third byte of EVEX prefix");
unconsumeByte(insn); /* unconsume byte1 */
unconsumeByte(insn); /* unconsume byte */
} else {
if ((insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0) &&
((~byte1 & 0xc) == 0xc) && ((byte2 & 0x4) == 0x4)) {
insn->vectorExtensionType = TYPE_EVEX;
} else {
unconsumeByte(insn); /* unconsume byte1 */
unconsumeByte(insn); /* unconsume byte */
}
}
if (insn->vectorExtensionType == TYPE_EVEX) {
insn->vectorExtensionPrefix[0] = byte;
insn->vectorExtensionPrefix[1] = byte1;
if (consumeByte(insn, &insn->vectorExtensionPrefix[2])) {
// dbgprintf(insn, "Couldn't read third byte of EVEX prefix");
return -1;
}
if (consumeByte(insn, &insn->vectorExtensionPrefix[3])) {
// dbgprintf(insn, "Couldn't read fourth byte of EVEX prefix");
return -1;
}
/* We simulate the REX prefix for simplicity's sake */
if (insn->mode == MODE_64BIT) {
insn->rexPrefix = 0x40
| (wFromEVEX3of4(insn->vectorExtensionPrefix[2]) << 3)
| (rFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 2)
| (xFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 1)
| (bFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 0);
}
// dbgprintf(insn, "Found EVEX prefix 0x%hhx 0x%hhx 0x%hhx 0x%hhx",
// insn->vectorExtensionPrefix[0], insn->vectorExtensionPrefix[1],
// insn->vectorExtensionPrefix[2], insn->vectorExtensionPrefix[3]);
}
} else if (byte == 0xc4) {
uint8_t byte1;
if (lookAtByte(insn, &byte1)) {
// dbgprintf(insn, "Couldn't read second byte of VEX");
return -1;
}
if (insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0)
insn->vectorExtensionType = TYPE_VEX_3B;
else
unconsumeByte(insn);
if (insn->vectorExtensionType == TYPE_VEX_3B) {
insn->vectorExtensionPrefix[0] = byte;
consumeByte(insn, &insn->vectorExtensionPrefix[1]);
consumeByte(insn, &insn->vectorExtensionPrefix[2]);
/* We simulate the REX prefix for simplicity's sake */
if (insn->mode == MODE_64BIT)
insn->rexPrefix = 0x40
| (wFromVEX3of3(insn->vectorExtensionPrefix[2]) << 3)
| (rFromVEX2of3(insn->vectorExtensionPrefix[1]) << 2)
| (xFromVEX2of3(insn->vectorExtensionPrefix[1]) << 1)
| (bFromVEX2of3(insn->vectorExtensionPrefix[1]) << 0);
// dbgprintf(insn, "Found VEX prefix 0x%hhx 0x%hhx 0x%hhx",
// insn->vectorExtensionPrefix[0], insn->vectorExtensionPrefix[1],
// insn->vectorExtensionPrefix[2]);
}
} else if (byte == 0xc5) {
uint8_t byte1;
if (lookAtByte(insn, &byte1)) {
// dbgprintf(insn, "Couldn't read second byte of VEX");
return -1;
}
if (insn->mode == MODE_64BIT || (byte1 & 0xc0) == 0xc0)
insn->vectorExtensionType = TYPE_VEX_2B;
else
unconsumeByte(insn);
if (insn->vectorExtensionType == TYPE_VEX_2B) {
insn->vectorExtensionPrefix[0] = byte;
consumeByte(insn, &insn->vectorExtensionPrefix[1]);
if (insn->mode == MODE_64BIT)
insn->rexPrefix = 0x40
| (rFromVEX2of2(insn->vectorExtensionPrefix[1]) << 2);
switch (ppFromVEX2of2(insn->vectorExtensionPrefix[1])) {
default:
break;
case VEX_PREFIX_66:
insn->hasOpSize = true;
break;
}
// dbgprintf(insn, "Found VEX prefix 0x%hhx 0x%hhx",
// insn->vectorExtensionPrefix[0],
// insn->vectorExtensionPrefix[1]);
}
} else if (byte == 0x8f) {
uint8_t byte1;
if (lookAtByte(insn, &byte1)) {
// dbgprintf(insn, "Couldn't read second byte of XOP");
return -1;
}
if ((byte1 & 0x38) != 0x0) /* 0 in these 3 bits is a POP instruction. */
insn->vectorExtensionType = TYPE_XOP;
else
unconsumeByte(insn);
if (insn->vectorExtensionType == TYPE_XOP) {
insn->vectorExtensionPrefix[0] = byte;
consumeByte(insn, &insn->vectorExtensionPrefix[1]);
consumeByte(insn, &insn->vectorExtensionPrefix[2]);
/* We simulate the REX prefix for simplicity's sake */
if (insn->mode == MODE_64BIT)
insn->rexPrefix = 0x40
| (wFromXOP3of3(insn->vectorExtensionPrefix[2]) << 3)
| (rFromXOP2of3(insn->vectorExtensionPrefix[1]) << 2)
| (xFromXOP2of3(insn->vectorExtensionPrefix[1]) << 1)
| (bFromXOP2of3(insn->vectorExtensionPrefix[1]) << 0);
switch (ppFromXOP3of3(insn->vectorExtensionPrefix[2])) {
default:
break;
case VEX_PREFIX_66:
insn->hasOpSize = true;
break;
}
// dbgprintf(insn, "Found XOP prefix 0x%hhx 0x%hhx 0x%hhx",
// insn->vectorExtensionPrefix[0], insn->vectorExtensionPrefix[1],
// insn->vectorExtensionPrefix[2]);
}
} else if (isREX(insn, byte)) {
if (lookAtByte(insn, &nextByte))
return -1;
insn->rexPrefix = byte;
// dbgprintf(insn, "Found REX prefix 0x%hhx", byte);
} else
unconsumeByte(insn);
if (insn->mode == MODE_16BIT) {
insn->registerSize = (insn->hasOpSize ? 4 : 2);
insn->addressSize = (insn->hasAdSize ? 4 : 2);
insn->displacementSize = (insn->hasAdSize ? 4 : 2);
insn->immediateSize = (insn->hasOpSize ? 4 : 2);
insn->immSize = (insn->hasOpSize ? 4 : 2);
} else if (insn->mode == MODE_32BIT) {
insn->registerSize = (insn->hasOpSize ? 2 : 4);
insn->addressSize = (insn->hasAdSize ? 2 : 4);
insn->displacementSize = (insn->hasAdSize ? 2 : 4);
insn->immediateSize = (insn->hasOpSize ? 2 : 4);
insn->immSize = (insn->hasOpSize ? 2 : 4);
} else if (insn->mode == MODE_64BIT) {
if (insn->rexPrefix && wFromREX(insn->rexPrefix)) {
insn->registerSize = 8;
insn->addressSize = (insn->hasAdSize ? 4 : 8);
insn->displacementSize = 4;
insn->immediateSize = 4;
insn->immSize = 4;
} else {
insn->registerSize = (insn->hasOpSize ? 2 : 4);
insn->addressSize = (insn->hasAdSize ? 4 : 8);
insn->displacementSize = (insn->hasOpSize ? 2 : 4);
insn->immediateSize = (insn->hasOpSize ? 2 : 4);
insn->immSize = (insn->hasOpSize ? 4 : 8);
}
}
return 0;
}
static int readModRM(struct InternalInstruction* insn);
/*
* readOpcode - Reads the opcode (excepting the ModR/M byte in the case of
* extended or escape opcodes).
*
* @param insn - The instruction whose opcode is to be read.
* @return - 0 if the opcode could be read successfully; nonzero otherwise.
*/
static int readOpcode(struct InternalInstruction* insn)
{
uint8_t current;
// dbgprintf(insn, "readOpcode()");
insn->opcodeType = ONEBYTE;
if (insn->vectorExtensionType == TYPE_EVEX) {
switch (mmFromEVEX2of4(insn->vectorExtensionPrefix[1])) {
default:
// dbgprintf(insn, "Unhandled mm field for instruction (0x%hhx)",
// mmFromEVEX2of4(insn->vectorExtensionPrefix[1]));
return -1;
case VEX_LOB_0F:
insn->opcodeType = TWOBYTE;
return consumeByte(insn, &insn->opcode);
case VEX_LOB_0F38:
insn->opcodeType = THREEBYTE_38;
return consumeByte(insn, &insn->opcode);
case VEX_LOB_0F3A:
insn->opcodeType = THREEBYTE_3A;
return consumeByte(insn, &insn->opcode);
}
} else if (insn->vectorExtensionType == TYPE_VEX_3B) {
switch (mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1])) {
default:
// dbgprintf(insn, "Unhandled m-mmmm field for instruction (0x%hhx)",
// mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1]));
return -1;
case VEX_LOB_0F:
//insn->twoByteEscape = 0x0f;
insn->opcodeType = TWOBYTE;
return consumeByte(insn, &insn->opcode);
case VEX_LOB_0F38:
//insn->twoByteEscape = 0x0f;
insn->opcodeType = THREEBYTE_38;
return consumeByte(insn, &insn->opcode);
case VEX_LOB_0F3A:
//insn->twoByteEscape = 0x0f;
insn->opcodeType = THREEBYTE_3A;
return consumeByte(insn, &insn->opcode);
}
} else if (insn->vectorExtensionType == TYPE_VEX_2B) {
//insn->twoByteEscape = 0x0f;
insn->opcodeType = TWOBYTE;
return consumeByte(insn, &insn->opcode);
} else if (insn->vectorExtensionType == TYPE_XOP) {
switch (mmmmmFromXOP2of3(insn->vectorExtensionPrefix[1])) {
default:
// dbgprintf(insn, "Unhandled m-mmmm field for instruction (0x%hhx)",
// mmmmmFromVEX2of3(insn->vectorExtensionPrefix[1]));
return -1;
case XOP_MAP_SELECT_8:
insn->opcodeType = XOP8_MAP;
return consumeByte(insn, &insn->opcode);
case XOP_MAP_SELECT_9:
insn->opcodeType = XOP9_MAP;
return consumeByte(insn, &insn->opcode);
case XOP_MAP_SELECT_A:
insn->opcodeType = XOPA_MAP;
return consumeByte(insn, &insn->opcode);
}
}
if (consumeByte(insn, &current))
return -1;
// save this first byte for MOVcr, MOVdr, MOVrc, MOVrd
insn->firstByte = current;
if (current == 0x0f) {
// dbgprintf(insn, "Found a two-byte escape prefix (0x%hhx)", current);
insn->twoByteEscape = current;
if (consumeByte(insn, &current))
return -1;
if (current == 0x38) {
// dbgprintf(insn, "Found a three-byte escape prefix (0x%hhx)", current);
if (consumeByte(insn, &current))
return -1;
insn->opcodeType = THREEBYTE_38;
} else if (current == 0x3a) {
// dbgprintf(insn, "Found a three-byte escape prefix (0x%hhx)", current);
if (consumeByte(insn, &current))
return -1;
insn->opcodeType = THREEBYTE_3A;
} else if (current == 0x0f) {
// dbgprintf(insn, "Found a 3dnow escape prefix (0x%hhx)", current);
// Consume operands before the opcode to comply with the 3DNow encoding
if (readModRM(insn))
return -1;
if (consumeByte(insn, &current))
return -1;
insn->opcodeType = THREEDNOW_MAP;
} else {
// dbgprintf(insn, "Didn't find a three-byte escape prefix");
insn->opcodeType = TWOBYTE;
}
} else if (insn->mandatoryPrefix)
// The opcode with mandatory prefix must start with opcode escape.
// If not it's legacy repeat prefix
insn->mandatoryPrefix = 0;
/*
* At this point we have consumed the full opcode.
* Anything we consume from here on must be unconsumed.
*/
insn->opcode = current;
return 0;
}
// Hacky for FEMMS
#define GET_INSTRINFO_ENUM
#ifndef CAPSTONE_X86_REDUCE
#include "X86GenInstrInfo.inc"
#else
#include "X86GenInstrInfo_reduce.inc"
#endif
/*
* getIDWithAttrMask - Determines the ID of an instruction, consuming
* the ModR/M byte as appropriate for extended and escape opcodes,
* and using a supplied attribute mask.
*
* @param instructionID - A pointer whose target is filled in with the ID of the
* instruction.
* @param insn - The instruction whose ID is to be determined.
* @param attrMask - The attribute mask to search.
* @return - 0 if the ModR/M could be read when needed or was not
* needed; nonzero otherwise.
*/
static int getIDWithAttrMask(uint16_t *instructionID,
struct InternalInstruction* insn,
uint16_t attrMask)
{
bool hasModRMExtension;
InstructionContext instructionClass = contextForAttrs(attrMask);
hasModRMExtension = modRMRequired(insn->opcodeType,
instructionClass,
insn->opcode);
if (hasModRMExtension) {
if (readModRM(insn))
return -1;
*instructionID = decode(insn->opcodeType,
instructionClass,
insn->opcode,
insn->modRM);
} else {
*instructionID = decode(insn->opcodeType,
instructionClass,
insn->opcode,
0);
}
return 0;
}
/*
* is16BitEquivalent - Determines whether two instruction names refer to
* equivalent instructions but one is 16-bit whereas the other is not.
*
* @param orig - The instruction ID that is not 16-bit
* @param equiv - The instruction ID that is 16-bit
*/
static bool is16BitEquivalent(unsigned orig, unsigned equiv)
{
size_t i;
uint16_t idx;
if ((idx = x86_16_bit_eq_lookup[orig]) != 0) {
for (i = idx - 1; i < ARR_SIZE(x86_16_bit_eq_tbl) && x86_16_bit_eq_tbl[i].first == orig; i++) {
if (x86_16_bit_eq_tbl[i].second == equiv)
return true;
}
}
return false;
}
/*
* is64Bit - Determines whether this instruction is a 64-bit instruction.
*
* @param name - The instruction that is not 16-bit
*/
static bool is64Bit(uint16_t id)
{
unsigned int i = find_insn(id);
if (i != -1) {
return insns[i].is64bit;
}
// not found??
return false;
}
/*
* getID - Determines the ID of an instruction, consuming the ModR/M byte as
* appropriate for extended and escape opcodes. Determines the attributes and
* context for the instruction before doing so.
*
* @param insn - The instruction whose ID is to be determined.
* @return - 0 if the ModR/M could be read when needed or was not needed;
* nonzero otherwise.
*/
static int getID(struct InternalInstruction *insn)
{
uint16_t attrMask;
uint16_t instructionID;
attrMask = ATTR_NONE;
if (insn->mode == MODE_64BIT)
attrMask |= ATTR_64BIT;
if (insn->vectorExtensionType != TYPE_NO_VEX_XOP) {
attrMask |= (insn->vectorExtensionType == TYPE_EVEX) ? ATTR_EVEX : ATTR_VEX;
if (insn->vectorExtensionType == TYPE_EVEX) {
switch (ppFromEVEX3of4(insn->vectorExtensionPrefix[2])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (zFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXKZ;
if (bFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXB;
if (aaaFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXK;
if (lFromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXL;
if (l2FromEVEX4of4(insn->vectorExtensionPrefix[3]))
attrMask |= ATTR_EVEXL2;
} else if (insn->vectorExtensionType == TYPE_VEX_3B) {
switch (ppFromVEX3of3(insn->vectorExtensionPrefix[2])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (lFromVEX3of3(insn->vectorExtensionPrefix[2]))
attrMask |= ATTR_VEXL;
} else if (insn->vectorExtensionType == TYPE_VEX_2B) {
switch (ppFromVEX2of2(insn->vectorExtensionPrefix[1])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (lFromVEX2of2(insn->vectorExtensionPrefix[1]))
attrMask |= ATTR_VEXL;
} else if (insn->vectorExtensionType == TYPE_XOP) {
switch (ppFromXOP3of3(insn->vectorExtensionPrefix[2])) {
case VEX_PREFIX_66:
attrMask |= ATTR_OPSIZE;
break;
case VEX_PREFIX_F3:
attrMask |= ATTR_XS;
break;
case VEX_PREFIX_F2:
attrMask |= ATTR_XD;
break;
}
if (lFromXOP3of3(insn->vectorExtensionPrefix[2]))
attrMask |= ATTR_VEXL;
} else {
return -1;
}
} else if (!insn->mandatoryPrefix) {
// If we don't have mandatory prefix we should use legacy prefixes here
if (insn->hasOpSize && (insn->mode != MODE_16BIT))
attrMask |= ATTR_OPSIZE;
if (insn->hasAdSize)
attrMask |= ATTR_ADSIZE;
if (insn->opcodeType == ONEBYTE) {
if (insn->repeatPrefix == 0xf3 && (insn->opcode == 0x90))
// Special support for PAUSE
attrMask |= ATTR_XS;
} else {
if (insn->repeatPrefix == 0xf2)
attrMask |= ATTR_XD;
else if (insn->repeatPrefix == 0xf3)
attrMask |= ATTR_XS;
}
} else {
switch (insn->mandatoryPrefix) {
case 0xf2:
attrMask |= ATTR_XD;
break;
case 0xf3:
attrMask |= ATTR_XS;
break;
case 0x66:
if (insn->mode != MODE_16BIT)
attrMask |= ATTR_OPSIZE;
break;
case 0x67:
attrMask |= ATTR_ADSIZE;
break;
}
}
if (insn->rexPrefix & 0x08) {
attrMask |= ATTR_REXW;
attrMask &= ~ATTR_ADSIZE;
}
/*
* JCXZ/JECXZ need special handling for 16-bit mode because the meaning
* of the AdSize prefix is inverted w.r.t. 32-bit mode.
*/
if (insn->mode == MODE_16BIT && insn->opcodeType == ONEBYTE &&
insn->opcode == 0xE3)
attrMask ^= ATTR_ADSIZE;
/*
* In 64-bit mode all f64 superscripted opcodes ignore opcode size prefix
* CALL/JMP/JCC instructions need to ignore 0x66 and consume 4 bytes
*/
if ((insn->mode == MODE_64BIT) && insn->hasOpSize) {
switch (insn->opcode) {
case 0xE8:
case 0xE9:
// Take care of psubsb and other mmx instructions.
if (insn->opcodeType == ONEBYTE) {
attrMask ^= ATTR_OPSIZE;
insn->immediateSize = 4;
insn->displacementSize = 4;
}
break;
case 0x82:
case 0x83:
case 0x84:
case 0x85:
case 0x86:
case 0x87:
case 0x88:
case 0x89:
case 0x8A:
case 0x8B:
case 0x8C:
case 0x8D:
case 0x8E:
case 0x8F:
// Take care of lea and three byte ops.
if (insn->opcodeType == TWOBYTE) {
attrMask ^= ATTR_OPSIZE;
insn->immediateSize = 4;
insn->displacementSize = 4;
}
break;
}
}
/* The following clauses compensate for limitations of the tables. */
if (insn->mode != MODE_64BIT &&
insn->vectorExtensionType != TYPE_NO_VEX_XOP) {
if (getIDWithAttrMask(&instructionID, insn, attrMask)) {
return -1;
}
/*
* The tables can't distinguish between cases where the W-bit is used to
* select register size and cases where it's a required part of the opcode.
*/
if ((insn->vectorExtensionType == TYPE_EVEX &&
wFromEVEX3of4(insn->vectorExtensionPrefix[2])) ||
(insn->vectorExtensionType == TYPE_VEX_3B &&
wFromVEX3of3(insn->vectorExtensionPrefix[2])) ||
(insn->vectorExtensionType == TYPE_XOP &&
wFromXOP3of3(insn->vectorExtensionPrefix[2]))) {
uint16_t instructionIDWithREXW;
if (getIDWithAttrMask(&instructionIDWithREXW,
insn, attrMask | ATTR_REXW)) {
insn->instructionID = instructionID;
insn->spec = specifierForUID(instructionID);
return 0;
}
// If not a 64-bit instruction. Switch the opcode.
if (!is64Bit(instructionIDWithREXW)) {
insn->instructionID = instructionIDWithREXW;
insn->spec = specifierForUID(instructionIDWithREXW);
return 0;
}
}
}
/*
* Absolute moves, umonitor, and movdir64b need special handling.
* -For 16-bit mode because the meaning of the AdSize and OpSize prefixes are
* inverted w.r.t.
* -For 32-bit mode we need to ensure the ADSIZE prefix is observed in
* any position.
*/
if ((insn->opcodeType == ONEBYTE && ((insn->opcode & 0xFC) == 0xA0)) ||
(insn->opcodeType == TWOBYTE && (insn->opcode == 0xAE)) ||
(insn->opcodeType == THREEBYTE_38 && insn->opcode == 0xF8)) {
/* Make sure we observed the prefixes in any position. */
if (insn->hasAdSize)
attrMask |= ATTR_ADSIZE;
if (insn->hasOpSize)
attrMask |= ATTR_OPSIZE;
/* In 16-bit, invert the attributes. */
if (insn->mode == MODE_16BIT) {
attrMask ^= ATTR_ADSIZE;
/* The OpSize attribute is only valid with the absolute moves. */
if (insn->opcodeType == ONEBYTE && ((insn->opcode & 0xFC) == 0xA0))
attrMask ^= ATTR_OPSIZE;
}
if (getIDWithAttrMask(&instructionID, insn, attrMask)) {
return -1;
}
insn->instructionID = instructionID;
insn->spec = specifierForUID(instructionID);
return 0;
}
if (getIDWithAttrMask(&instructionID, insn, attrMask)) {
return -1;
}
if ((insn->mode == MODE_16BIT || insn->hasOpSize) &&
!(attrMask & ATTR_OPSIZE)) {
/*
* The instruction tables make no distinction between instructions that
* allow OpSize anywhere (i.e., 16-bit operations) and that need it in a
* particular spot (i.e., many MMX operations). In general we're
* conservative, but in the specific case where OpSize is present but not
* in the right place we check if there's a 16-bit operation.
*/
const struct InstructionSpecifier *spec;
uint16_t instructionIDWithOpsize;
spec = specifierForUID(instructionID);
if (getIDWithAttrMask(&instructionIDWithOpsize,
insn,
attrMask | ATTR_OPSIZE)) {
/*
* ModRM required with OpSize but not present; give up and return version
* without OpSize set
*/
insn->instructionID = instructionID;
insn->spec = spec;
return 0;
}
if (is16BitEquivalent(instructionID, instructionIDWithOpsize) &&
(insn->mode == MODE_16BIT) ^ insn->hasOpSize) {
insn->instructionID = instructionIDWithOpsize;
insn->spec = specifierForUID(instructionIDWithOpsize);
} else {
insn->instructionID = instructionID;
insn->spec = spec;
}
return 0;
}
if (insn->opcodeType == ONEBYTE && insn->opcode == 0x90 &&
insn->rexPrefix & 0x01) {
/*
* NOOP shouldn't decode as NOOP if REX.b is set. Instead
* it should decode as XCHG %r8, %eax.
*/
const struct InstructionSpecifier *spec;
uint16_t instructionIDWithNewOpcode;
const struct InstructionSpecifier *specWithNewOpcode;
spec = specifierForUID(instructionID);
/* Borrow opcode from one of the other XCHGar opcodes */
insn->opcode = 0x91;
if (getIDWithAttrMask(&instructionIDWithNewOpcode, insn, attrMask)) {
insn->opcode = 0x90;
insn->instructionID = instructionID;
insn->spec = spec;
return 0;
}
specWithNewOpcode = specifierForUID(instructionIDWithNewOpcode);
/* Change back */
insn->opcode = 0x90;
insn->instructionID = instructionIDWithNewOpcode;
insn->spec = specWithNewOpcode;
return 0;
}
insn->instructionID = instructionID;
insn->spec = specifierForUID(insn->instructionID);
return 0;
}
/*
* readSIB - Consumes the SIB byte to determine addressing information for an
* instruction.
*
* @param insn - The instruction whose SIB byte is to be read.
* @return - 0 if the SIB byte was successfully read; nonzero otherwise.
*/
static int readSIB(struct InternalInstruction* insn)
{
SIBBase sibBaseBase = SIB_BASE_NONE;
uint8_t index, base;
// dbgprintf(insn, "readSIB()");
if (insn->consumedSIB)
return 0;
insn->consumedSIB = true;
switch (insn->addressSize) {
case 2:
// dbgprintf(insn, "SIB-based addressing doesn't work in 16-bit mode");
return -1;
case 4:
insn->sibIndexBase = SIB_INDEX_EAX;
sibBaseBase = SIB_BASE_EAX;
break;
case 8:
insn->sibIndexBase = SIB_INDEX_RAX;
sibBaseBase = SIB_BASE_RAX;
break;
}
if (consumeByte(insn, &insn->sib))
return -1;
index = indexFromSIB(insn->sib) | (xFromREX(insn->rexPrefix) << 3);
if (index == 0x4) {
insn->sibIndex = SIB_INDEX_NONE;
} else {
insn->sibIndex = (SIBIndex)(insn->sibIndexBase + index);
}
insn->sibScale = 1 << scaleFromSIB(insn->sib);
base = baseFromSIB(insn->sib) | (bFromREX(insn->rexPrefix) << 3);
switch (base) {
case 0x5:
case 0xd:
switch (modFromModRM(insn->modRM)) {
case 0x0:
insn->eaDisplacement = EA_DISP_32;
insn->sibBase = SIB_BASE_NONE;
break;
case 0x1:
insn->eaDisplacement = EA_DISP_8;
insn->sibBase = (SIBBase)(sibBaseBase + base);
break;
case 0x2:
insn->eaDisplacement = EA_DISP_32;
insn->sibBase = (SIBBase)(sibBaseBase + base);
break;
case 0x3:
// debug("Cannot have Mod = 0b11 and a SIB byte");
return -1;
}
break;
default:
insn->sibBase = (SIBBase)(sibBaseBase + base);
break;
}
return 0;
}
/*
* readDisplacement - Consumes the displacement of an instruction.
*
* @param insn - The instruction whose displacement is to be read.
* @return - 0 if the displacement byte was successfully read; nonzero
* otherwise.
*/
static int readDisplacement(struct InternalInstruction* insn)
{
int8_t d8;
int16_t d16;
int32_t d32;
// dbgprintf(insn, "readDisplacement()");
if (insn->consumedDisplacement)
return 0;
insn->consumedDisplacement = true;
insn->displacementOffset = insn->readerCursor - insn->startLocation;
switch (insn->eaDisplacement) {
case EA_DISP_NONE:
insn->consumedDisplacement = false;
break;
case EA_DISP_8:
if (consumeInt8(insn, &d8))
return -1;
insn->displacement = d8;
break;
case EA_DISP_16:
if (consumeInt16(insn, &d16))
return -1;
insn->displacement = d16;
break;
case EA_DISP_32:
if (consumeInt32(insn, &d32))
return -1;
insn->displacement = d32;
break;
}
return 0;
}
/*
* readModRM - Consumes all addressing information (ModR/M byte, SIB byte, and
* displacement) for an instruction and interprets it.
*
* @param insn - The instruction whose addressing information is to be read.
* @return - 0 if the information was successfully read; nonzero otherwise.
*/
static int readModRM(struct InternalInstruction* insn)
{
uint8_t mod, rm, reg, evexrm;
// dbgprintf(insn, "readModRM()");
if (insn->consumedModRM)
return 0;
insn->modRMOffset = (uint8_t)(insn->readerCursor - insn->startLocation);
if (consumeByte(insn, &insn->modRM))
return -1;
insn->consumedModRM = true;
// save original ModRM for later reference
insn->orgModRM = insn->modRM;
// handle MOVcr, MOVdr, MOVrc, MOVrd by pretending they have MRM.mod = 3
if ((insn->firstByte == 0x0f && insn->opcodeType == TWOBYTE) &&
(insn->opcode >= 0x20 && insn->opcode <= 0x23 ))
insn->modRM |= 0xC0;
mod = modFromModRM(insn->modRM);
rm = rmFromModRM(insn->modRM);
reg = regFromModRM(insn->modRM);
/*
* This goes by insn->registerSize to pick the correct register, which messes
* up if we're using (say) XMM or 8-bit register operands. That gets fixed in
* fixupReg().
*/
switch (insn->registerSize) {
case 2:
insn->regBase = MODRM_REG_AX;
insn->eaRegBase = EA_REG_AX;
break;
case 4:
insn->regBase = MODRM_REG_EAX;
insn->eaRegBase = EA_REG_EAX;
break;
case 8:
insn->regBase = MODRM_REG_RAX;
insn->eaRegBase = EA_REG_RAX;
break;
}
reg |= rFromREX(insn->rexPrefix) << 3;
rm |= bFromREX(insn->rexPrefix) << 3;
evexrm = 0;
if (insn->vectorExtensionType == TYPE_EVEX && insn->mode == MODE_64BIT) {
reg |= r2FromEVEX2of4(insn->vectorExtensionPrefix[1]) << 4;
evexrm = xFromEVEX2of4(insn->vectorExtensionPrefix[1]) << 4;
}
insn->reg = (Reg)(insn->regBase + reg);
switch (insn->addressSize) {
case 2: {
EABase eaBaseBase = EA_BASE_BX_SI;
switch (mod) {
case 0x0:
if (rm == 0x6) {
insn->eaBase = EA_BASE_NONE;
insn->eaDisplacement = EA_DISP_16;
if (readDisplacement(insn))
return -1;
} else {
insn->eaBase = (EABase)(eaBaseBase + rm);
insn->eaDisplacement = EA_DISP_NONE;
}
break;
case 0x1:
insn->eaBase = (EABase)(eaBaseBase + rm);
insn->eaDisplacement = EA_DISP_8;
insn->displacementSize = 1;
if (readDisplacement(insn))
return -1;
break;
case 0x2:
insn->eaBase = (EABase)(eaBaseBase + rm);
insn->eaDisplacement = EA_DISP_16;
if (readDisplacement(insn))
return -1;
break;
case 0x3:
insn->eaBase = (EABase)(insn->eaRegBase + rm);
if (readDisplacement(insn))
return -1;
break;
}
break;
}
case 4:
case 8: {
EABase eaBaseBase = (insn->addressSize == 4 ? EA_BASE_EAX : EA_BASE_RAX);
switch (mod) {
default: break;
case 0x0:
insn->eaDisplacement = EA_DISP_NONE; /* readSIB may override this */
// In determining whether RIP-relative mode is used (rm=5),
// or whether a SIB byte is present (rm=4),
// the extension bits (REX.b and EVEX.x) are ignored.
switch (rm & 7) {
case 0x4: // SIB byte is present
insn->eaBase = (insn->addressSize == 4 ?
EA_BASE_sib : EA_BASE_sib64);
if (readSIB(insn) || readDisplacement(insn))
return -1;
break;
case 0x5: // RIP-relative
insn->eaBase = EA_BASE_NONE;
insn->eaDisplacement = EA_DISP_32;
if (readDisplacement(insn))
return -1;
break;
default:
insn->eaBase = (EABase)(eaBaseBase + rm);
break;
}
break;
case 0x1:
insn->displacementSize = 1;
/* FALLTHROUGH */
case 0x2:
insn->eaDisplacement = (mod == 0x1 ? EA_DISP_8 : EA_DISP_32);
switch (rm & 7) {
case 0x4: // SIB byte is present
insn->eaBase = EA_BASE_sib;
if (readSIB(insn) || readDisplacement(insn))
return -1;
break;
default:
insn->eaBase = (EABase)(eaBaseBase + rm);
if (readDisplacement(insn))
return -1;
break;
}
break;
case 0x3:
insn->eaDisplacement = EA_DISP_NONE;
insn->eaBase = (EABase)(insn->eaRegBase + rm + evexrm);
break;
}
break;
}
} /* switch (insn->addressSize) */
return 0;
}
#define GENERIC_FIXUP_FUNC(name, base, prefix, mask) \
static uint16_t name(struct InternalInstruction *insn, \
OperandType type, \
uint8_t index, \
uint8_t *valid) { \
*valid = 1; \
switch (type) { \
default: \
*valid = 0; \
return 0; \
case TYPE_Rv: \
return base + index; \
case TYPE_R8: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
if (insn->rexPrefix && \
index >= 4 && index <= 7) { \
return prefix##_SPL + (index - 4); \
} else { \
return prefix##_AL + index; \
} \
case TYPE_R16: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
return prefix##_AX + index; \
case TYPE_R32: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
return prefix##_EAX + index; \
case TYPE_R64: \
index &= mask; \
if (index > 0xf) \
*valid = 0; \
return prefix##_RAX + index; \
case TYPE_ZMM: \
return prefix##_ZMM0 + index; \
case TYPE_YMM: \
return prefix##_YMM0 + index; \
case TYPE_XMM: \
return prefix##_XMM0 + index; \
case TYPE_VK: \
index &= 0xf; \
if (index > 7) \
*valid = 0; \
return prefix##_K0 + index; \
case TYPE_MM64: \
return prefix##_MM0 + (index & 0x7); \
case TYPE_SEGMENTREG: \
if ((index & 7) > 5) \
*valid = 0; \
return prefix##_ES + (index & 7); \
case TYPE_DEBUGREG: \
return prefix##_DR0 + index; \
case TYPE_CONTROLREG: \
return prefix##_CR0 + index; \
case TYPE_BNDR: \
if (index > 3) \
*valid = 0; \
return prefix##_BND0 + index; \
case TYPE_MVSIBX: \
return prefix##_XMM0 + index; \
case TYPE_MVSIBY: \
return prefix##_YMM0 + index; \
case TYPE_MVSIBZ: \
return prefix##_ZMM0 + index; \
} \
}
/*
* fixup*Value - Consults an operand type to determine the meaning of the
* reg or R/M field. If the operand is an XMM operand, for example, an
* operand would be XMM0 instead of AX, which readModRM() would otherwise
* misinterpret it as.
*
* @param insn - The instruction containing the operand.
* @param type - The operand type.
* @param index - The existing value of the field as reported by readModRM().
* @param valid - The address of a uint8_t. The target is set to 1 if the
* field is valid for the register class; 0 if not.
* @return - The proper value.
*/
GENERIC_FIXUP_FUNC(fixupRegValue, insn->regBase, MODRM_REG, 0x1f)
GENERIC_FIXUP_FUNC(fixupRMValue, insn->eaRegBase, EA_REG, 0xf)
/*
* fixupReg - Consults an operand specifier to determine which of the
* fixup*Value functions to use in correcting readModRM()'ss interpretation.
*
* @param insn - See fixup*Value().
* @param op - The operand specifier.
* @return - 0 if fixup was successful; -1 if the register returned was
* invalid for its class.
*/
static int fixupReg(struct InternalInstruction *insn,
const struct OperandSpecifier *op)
{
uint8_t valid;
switch ((OperandEncoding)op->encoding) {
default:
// debug("Expected a REG or R/M encoding in fixupReg");
return -1;
case ENCODING_VVVV:
insn->vvvv = (Reg)fixupRegValue(insn,
(OperandType)op->type,
insn->vvvv,
&valid);
if (!valid)
return -1;
break;
case ENCODING_REG:
insn->reg = (Reg)fixupRegValue(insn,
(OperandType)op->type,
insn->reg - insn->regBase,
&valid);
if (!valid)
return -1;
break;
CASE_ENCODING_RM:
if (insn->eaBase >= insn->eaRegBase) {
insn->eaBase = (EABase)fixupRMValue(insn,
(OperandType)op->type,
insn->eaBase - insn->eaRegBase,
&valid);
if (!valid)
return -1;
}
break;
}
return 0;
}
/*
* readOpcodeRegister - Reads an operand from the opcode field of an
* instruction and interprets it appropriately given the operand width.
* Handles AddRegFrm instructions.
*
* @param insn - the instruction whose opcode field is to be read.
* @param size - The width (in bytes) of the register being specified.
* 1 means AL and friends, 2 means AX, 4 means EAX, and 8 means
* RAX.
* @return - 0 on success; nonzero otherwise.
*/
static int readOpcodeRegister(struct InternalInstruction* insn, uint8_t size)
{
if (size == 0)
size = insn->registerSize;
switch (size) {
case 1:
insn->opcodeRegister = (Reg)(MODRM_REG_AL + ((bFromREX(insn->rexPrefix) << 3)
| (insn->opcode & 7)));
if (insn->rexPrefix &&
insn->opcodeRegister >= MODRM_REG_AL + 0x4 &&
insn->opcodeRegister < MODRM_REG_AL + 0x8) {
insn->opcodeRegister = (Reg)(MODRM_REG_SPL
+ (insn->opcodeRegister - MODRM_REG_AL - 4));
}
break;
case 2:
insn->opcodeRegister = (Reg)(MODRM_REG_AX
+ ((bFromREX(insn->rexPrefix) << 3)
| (insn->opcode & 7)));
break;
case 4:
insn->opcodeRegister = (Reg)(MODRM_REG_EAX
+ ((bFromREX(insn->rexPrefix) << 3)
| (insn->opcode & 7)));
break;
case 8:
insn->opcodeRegister = (Reg)(MODRM_REG_RAX
+ ((bFromREX(insn->rexPrefix) << 3)
| (insn->opcode & 7)));
break;
}
return 0;
}
/*
* readImmediate - Consumes an immediate operand from an instruction, given the
* desired operand size.
*
* @param insn - The instruction whose operand is to be read.
* @param size - The width (in bytes) of the operand.
* @return - 0 if the immediate was successfully consumed; nonzero
* otherwise.
*/
static int readImmediate(struct InternalInstruction* insn, uint8_t size)
{
uint8_t imm8;
uint16_t imm16;
uint32_t imm32;
uint64_t imm64;
if (insn->numImmediatesConsumed == 2) {
// debug("Already consumed two immediates");
return -1;
}
if (size == 0)
size = insn->immediateSize;
else
insn->immediateSize = size;
insn->immediateOffset = insn->readerCursor - insn->startLocation;
switch (size) {
case 1:
if (consumeByte(insn, &imm8))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm8;
break;
case 2:
if (consumeUInt16(insn, &imm16))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm16;
break;
case 4:
if (consumeUInt32(insn, &imm32))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm32;
break;
case 8:
if (consumeUInt64(insn, &imm64))
return -1;
insn->immediates[insn->numImmediatesConsumed] = imm64;
break;
}
insn->numImmediatesConsumed++;
return 0;
}
/*
* readVVVV - Consumes vvvv from an instruction if it has a VEX prefix.
*
* @param insn - The instruction whose operand is to be read.
* @return - 0 if the vvvv was successfully consumed; nonzero
* otherwise.
*/
static int readVVVV(struct InternalInstruction* insn)
{
int vvvv;
if (insn->vectorExtensionType == TYPE_EVEX)
vvvv = (v2FromEVEX4of4(insn->vectorExtensionPrefix[3]) << 4 |
vvvvFromEVEX3of4(insn->vectorExtensionPrefix[2]));
else if (insn->vectorExtensionType == TYPE_VEX_3B)
vvvv = vvvvFromVEX3of3(insn->vectorExtensionPrefix[2]);
else if (insn->vectorExtensionType == TYPE_VEX_2B)
vvvv = vvvvFromVEX2of2(insn->vectorExtensionPrefix[1]);
else if (insn->vectorExtensionType == TYPE_XOP)
vvvv = vvvvFromXOP3of3(insn->vectorExtensionPrefix[2]);
else
return -1;
if (insn->mode != MODE_64BIT)
vvvv &= 0xf; // Can only clear bit 4. Bit 3 must be cleared later.
insn->vvvv = (Reg)vvvv;
return 0;
}
/*
* readMaskRegister - Reads an mask register from the opcode field of an
* instruction.
*
* @param insn - The instruction whose opcode field is to be read.
* @return - 0 on success; nonzero otherwise.
*/
static int readMaskRegister(struct InternalInstruction* insn)
{
if (insn->vectorExtensionType != TYPE_EVEX)
return -1;
insn->writemask = (Reg)(aaaFromEVEX4of4(insn->vectorExtensionPrefix[3]));
return 0;
}
/*
* readOperands - Consults the specifier for an instruction and consumes all
* operands for that instruction, interpreting them as it goes.
*
* @param insn - The instruction whose operands are to be read and interpreted.
* @return - 0 if all operands could be read; nonzero otherwise.
*/
static int readOperands(struct InternalInstruction* insn)
{
int hasVVVV, needVVVV;
int sawRegImm = 0;
int i;
/* If non-zero vvvv specified, need to make sure one of the operands
uses it. */
hasVVVV = !readVVVV(insn);
needVVVV = hasVVVV && (insn->vvvv != 0);
for (i = 0; i < X86_MAX_OPERANDS; ++i) {
const OperandSpecifier *op = &x86OperandSets[insn->spec->operands][i];
switch (op->encoding) {
case ENCODING_NONE:
case ENCODING_SI:
case ENCODING_DI:
break;
CASE_ENCODING_VSIB:
// VSIB can use the V2 bit so check only the other bits.
if (needVVVV)
needVVVV = hasVVVV & ((insn->vvvv & 0xf) != 0);
if (readModRM(insn))
return -1;
// Reject if SIB wasn't used.
if (insn->eaBase != EA_BASE_sib && insn->eaBase != EA_BASE_sib64)
return -1;
// If sibIndex was set to SIB_INDEX_NONE, index offset is 4.
if (insn->sibIndex == SIB_INDEX_NONE)
insn->sibIndex = (SIBIndex)(insn->sibIndexBase + 4);
// If EVEX.v2 is set this is one of the 16-31 registers.
if (insn->vectorExtensionType == TYPE_EVEX && insn->mode == MODE_64BIT &&
v2FromEVEX4of4(insn->vectorExtensionPrefix[3]))
insn->sibIndex = (SIBIndex)(insn->sibIndex + 16);
// Adjust the index register to the correct size.
switch (op->type) {
default:
// debug("Unhandled VSIB index type");
return -1;
case TYPE_MVSIBX:
insn->sibIndex = (SIBIndex)(SIB_INDEX_XMM0 +
(insn->sibIndex - insn->sibIndexBase));
break;
case TYPE_MVSIBY:
insn->sibIndex = (SIBIndex)(SIB_INDEX_YMM0 +
(insn->sibIndex - insn->sibIndexBase));
break;
case TYPE_MVSIBZ:
insn->sibIndex = (SIBIndex)(SIB_INDEX_ZMM0 +
(insn->sibIndex - insn->sibIndexBase));
break;
}
// Apply the AVX512 compressed displacement scaling factor.
if (op->encoding != ENCODING_REG && insn->eaDisplacement == EA_DISP_8)
insn->displacement *= 1 << (op->encoding - ENCODING_VSIB);
break;
case ENCODING_REG:
CASE_ENCODING_RM:
if (readModRM(insn))
return -1;
if (fixupReg(insn, op))
return -1;
// Apply the AVX512 compressed displacement scaling factor.
if (op->encoding != ENCODING_REG && insn->eaDisplacement == EA_DISP_8)
insn->displacement *= 1 << (op->encoding - ENCODING_RM);
break;
case ENCODING_IB:
if (sawRegImm) {
/* Saw a register immediate so don't read again and instead split the
previous immediate. FIXME: This is a hack. */
insn->immediates[insn->numImmediatesConsumed] =
insn->immediates[insn->numImmediatesConsumed - 1] & 0xf;
++insn->numImmediatesConsumed;
break;
}
if (readImmediate(insn, 1))
return -1;
if (op->type == TYPE_XMM || op->type == TYPE_YMM)
sawRegImm = 1;
break;
case ENCODING_IW:
if (readImmediate(insn, 2))
return -1;
break;
case ENCODING_ID:
if (readImmediate(insn, 4))
return -1;
break;
case ENCODING_IO:
if (readImmediate(insn, 8))
return -1;
break;
case ENCODING_Iv:
if (readImmediate(insn, insn->immediateSize))
return -1;
break;
case ENCODING_Ia:
if (readImmediate(insn, insn->addressSize))
return -1;
/* Direct memory-offset (moffset) immediate will get mapped
to memory operand later. We want the encoding info to
reflect that as well. */
insn->displacementOffset = insn->immediateOffset;
insn->consumedDisplacement = true;
insn->displacementSize = insn->immediateSize;
insn->displacement = insn->immediates[insn->numImmediatesConsumed - 1];
insn->immediateOffset = 0;
insn->immediateSize = 0;
break;
case ENCODING_IRC:
insn->RC = (l2FromEVEX4of4(insn->vectorExtensionPrefix[3]) << 1) |
lFromEVEX4of4(insn->vectorExtensionPrefix[3]);
break;
case ENCODING_RB:
if (readOpcodeRegister(insn, 1))
return -1;
break;
case ENCODING_RW:
if (readOpcodeRegister(insn, 2))
return -1;
break;
case ENCODING_RD:
if (readOpcodeRegister(insn, 4))
return -1;
break;
case ENCODING_RO:
if (readOpcodeRegister(insn, 8))
return -1;
break;
case ENCODING_Rv:
if (readOpcodeRegister(insn, 0))
return -1;
break;
case ENCODING_FP:
break;
case ENCODING_VVVV:
if (!hasVVVV)
return -1;
needVVVV = 0; /* Mark that we have found a VVVV operand. */
if (insn->mode != MODE_64BIT)
insn->vvvv = (Reg)(insn->vvvv & 0x7);
if (fixupReg(insn, op))
return -1;
break;
case ENCODING_WRITEMASK:
if (readMaskRegister(insn))
return -1;
break;
case ENCODING_DUP:
break;
default:
// dbgprintf(insn, "Encountered an operand with an unknown encoding.");
return -1;
}
}
/* If we didn't find ENCODING_VVVV operand, but non-zero vvvv present, fail */
if (needVVVV)
return -1;
return 0;
}
// return True if instruction is illegal to use with prefixes
// This also check & fix the isPrefixNN when a prefix is irrelevant.
static bool checkPrefix(struct InternalInstruction *insn)
{
// LOCK prefix
if (insn->hasLockPrefix) {
switch(insn->instructionID) {
default:
// invalid LOCK
return true;
// nop dword [rax]
case X86_NOOPL:
// DEC
case X86_DEC16m:
case X86_DEC32m:
case X86_DEC64m:
case X86_DEC8m:
// ADC
case X86_ADC16mi:
case X86_ADC16mi8:
case X86_ADC16mr:
case X86_ADC32mi:
case X86_ADC32mi8:
case X86_ADC32mr:
case X86_ADC64mi32:
case X86_ADC64mi8:
case X86_ADC64mr:
case X86_ADC8mi:
case X86_ADC8mi8:
case X86_ADC8mr:
case X86_ADC8rm:
case X86_ADC16rm:
case X86_ADC32rm:
case X86_ADC64rm:
// ADD
case X86_ADD16mi:
case X86_ADD16mi8:
case X86_ADD16mr:
case X86_ADD32mi:
case X86_ADD32mi8:
case X86_ADD32mr:
case X86_ADD64mi32:
case X86_ADD64mi8:
case X86_ADD64mr:
case X86_ADD8mi:
case X86_ADD8mi8:
case X86_ADD8mr:
case X86_ADD8rm:
case X86_ADD16rm:
case X86_ADD32rm:
case X86_ADD64rm:
// AND
case X86_AND16mi:
case X86_AND16mi8:
case X86_AND16mr:
case X86_AND32mi:
case X86_AND32mi8:
case X86_AND32mr:
case X86_AND64mi32:
case X86_AND64mi8:
case X86_AND64mr:
case X86_AND8mi:
case X86_AND8mi8:
case X86_AND8mr:
case X86_AND8rm:
case X86_AND16rm:
case X86_AND32rm:
case X86_AND64rm:
// BTC
case X86_BTC16mi8:
case X86_BTC16mr:
case X86_BTC32mi8:
case X86_BTC32mr:
case X86_BTC64mi8:
case X86_BTC64mr:
// BTR
case X86_BTR16mi8:
case X86_BTR16mr:
case X86_BTR32mi8:
case X86_BTR32mr:
case X86_BTR64mi8:
case X86_BTR64mr:
// BTS
case X86_BTS16mi8:
case X86_BTS16mr:
case X86_BTS32mi8:
case X86_BTS32mr:
case X86_BTS64mi8:
case X86_BTS64mr:
// CMPXCHG
case X86_CMPXCHG16B:
case X86_CMPXCHG16rm:
case X86_CMPXCHG32rm:
case X86_CMPXCHG64rm:
case X86_CMPXCHG8rm:
case X86_CMPXCHG8B:
// INC
case X86_INC16m:
case X86_INC32m:
case X86_INC64m:
case X86_INC8m:
// NEG
case X86_NEG16m:
case X86_NEG32m:
case X86_NEG64m:
case X86_NEG8m:
// NOT
case X86_NOT16m:
case X86_NOT32m:
case X86_NOT64m:
case X86_NOT8m:
// OR
case X86_OR16mi:
case X86_OR16mi8:
case X86_OR16mr:
case X86_OR32mi:
case X86_OR32mi8:
case X86_OR32mr:
case X86_OR64mi32:
case X86_OR64mi8:
case X86_OR64mr:
case X86_OR8mi8:
case X86_OR8mi:
case X86_OR8mr:
case X86_OR8rm:
case X86_OR16rm:
case X86_OR32rm:
case X86_OR64rm:
// SBB
case X86_SBB16mi:
case X86_SBB16mi8:
case X86_SBB16mr:
case X86_SBB32mi:
case X86_SBB32mi8:
case X86_SBB32mr:
case X86_SBB64mi32:
case X86_SBB64mi8:
case X86_SBB64mr:
case X86_SBB8mi:
case X86_SBB8mi8:
case X86_SBB8mr:
// SUB
case X86_SUB16mi:
case X86_SUB16mi8:
case X86_SUB16mr:
case X86_SUB32mi:
case X86_SUB32mi8:
case X86_SUB32mr:
case X86_SUB64mi32:
case X86_SUB64mi8:
case X86_SUB64mr:
case X86_SUB8mi8:
case X86_SUB8mi:
case X86_SUB8mr:
case X86_SUB8rm:
case X86_SUB16rm:
case X86_SUB32rm:
case X86_SUB64rm:
// XADD
case X86_XADD16rm:
case X86_XADD32rm:
case X86_XADD64rm:
case X86_XADD8rm:
// XCHG
case X86_XCHG16rm:
case X86_XCHG32rm:
case X86_XCHG64rm:
case X86_XCHG8rm:
// XOR
case X86_XOR16mi:
case X86_XOR16mi8:
case X86_XOR16mr:
case X86_XOR32mi:
case X86_XOR32mi8:
case X86_XOR32mr:
case X86_XOR64mi32:
case X86_XOR64mi8:
case X86_XOR64mr:
case X86_XOR8mi8:
case X86_XOR8mi:
case X86_XOR8mr:
case X86_XOR8rm:
case X86_XOR16rm:
case X86_XOR32rm:
case X86_XOR64rm:
// this instruction can be used with LOCK prefix
return false;
}
}
#if 0
// REPNE prefix
if (insn->repeatPrefix) {
// 0xf2 can be a part of instruction encoding, but not really a prefix.
// In such a case, clear it.
if (insn->twoByteEscape == 0x0f) {
insn->prefix0 = 0;
}
}
#endif
// no invalid prefixes
return false;
}
/*
* decodeInstruction - Reads and interprets a full instruction provided by the
* user.
*
* @param insn - A pointer to the instruction to be populated. Must be
* pre-allocated.
* @param reader - The function to be used to read the instruction's bytes.
* @param readerArg - A generic argument to be passed to the reader to store
* any internal state.
* @param startLoc - The address (in the reader's address space) of the first
* byte in the instruction.
* @param mode - The mode (real mode, IA-32e, or IA-32e in 64-bit mode) to
* decode the instruction in.
* @return - 0 if instruction is valid; nonzero if not.
*/
int decodeInstruction(struct InternalInstruction *insn,
byteReader_t reader,
const void *readerArg,
uint64_t startLoc,
DisassemblerMode mode)
{
insn->reader = reader;
insn->readerArg = readerArg;
insn->startLocation = startLoc;
insn->readerCursor = startLoc;
insn->mode = mode;
insn->numImmediatesConsumed = 0;
if (readPrefixes(insn) ||
readOpcode(insn) ||
getID(insn) ||
insn->instructionID == 0 ||
checkPrefix(insn) ||
readOperands(insn))
return -1;
insn->length = (size_t)(insn->readerCursor - insn->startLocation);
// instruction length must be <= 15 to be valid
if (insn->length > 15)
return -1;
if (insn->operandSize == 0)
insn->operandSize = insn->registerSize;
insn->operands = &x86OperandSets[insn->spec->operands][0];
return 0;
}
#endif