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Diffstat (limited to 'src/arch/x86/predecoder.cc')
| -rw-r--r-- | src/arch/x86/predecoder.cc | 345 |
1 files changed, 345 insertions, 0 deletions
diff --git a/src/arch/x86/predecoder.cc b/src/arch/x86/predecoder.cc new file mode 100644 index 000000000..5ea960b36 --- /dev/null +++ b/src/arch/x86/predecoder.cc @@ -0,0 +1,345 @@ +/* + * Copyright (c) 2007 The Hewlett-Packard Development Company + * All rights reserved. + * + * Redistribution and use of this software in source and binary forms, + * with or without modification, are permitted provided that the + * following conditions are met: + * + * The software must be used only for Non-Commercial Use which means any + * use which is NOT directed to receiving any direct monetary + * compensation for, or commercial advantage from such use. Illustrative + * examples of non-commercial use are academic research, personal study, + * teaching, education and corporate research & development. + * Illustrative examples of commercial use are distributing products for + * commercial advantage and providing services using the software for + * commercial advantage. + * + * If you wish to use this software or functionality therein that may be + * covered by patents for commercial use, please contact: + * Director of Intellectual Property Licensing + * Office of Strategy and Technology + * Hewlett-Packard Company + * 1501 Page Mill Road + * Palo Alto, California 94304 + * + * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. Redistributions + * in binary form must reproduce the above copyright notice, this list of + * conditions and the following disclaimer in the documentation and/or + * other materials provided with the distribution. Neither the name of + * the COPYRIGHT HOLDER(s), HEWLETT-PACKARD COMPANY, nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. No right of + * sublicense is granted herewith. Derivatives of the software and + * output created using the software may be prepared, but only for + * Non-Commercial Uses. Derivatives of the software may be shared with + * others provided: (i) the others agree to abide by the list of + * conditions herein which includes the Non-Commercial Use restrictions; + * and (ii) such Derivatives of the software include the above copyright + * notice to acknowledge the contribution from this software where + * applicable, this list of conditions and the disclaimer below. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * Authors: Gabe Black + */ + +#include "arch/x86/predecoder.hh" +#include "base/misc.hh" +#include "base/trace.hh" +#include "sim/host.hh" + +namespace X86ISA +{ + void Predecoder::process() + { + //This function drives the predecoder state machine. + + //Some sanity checks. You shouldn't try to process more bytes if + //there aren't any, and you shouldn't overwrite an already + //predecoder ExtMachInst. + assert(!outOfBytes); + assert(!emiIsReady); + + //While there's still something to do... + while(!emiIsReady && !outOfBytes) + { + uint8_t nextByte = getNextByte(); + switch(state) + { + case Prefix: + state = doPrefixState(nextByte); + break; + case Opcode: + state = doOpcodeState(nextByte); + break; + case ModRM: + state = doModRMState(nextByte); + break; + case SIB: + state = doSIBState(nextByte); + break; + case Displacement: + state = doDisplacementState(); + break; + case Immediate: + state = doImmediateState(); + break; + case ErrorState: + panic("Went to the error state in the predecoder.\n"); + default: + panic("Unrecognized state! %d\n", state); + } + } + } + + //Either get a prefix and record it in the ExtMachInst, or send the + //state machine on to get the opcode(s). + Predecoder::State Predecoder::doPrefixState(uint8_t nextByte) + { + uint8_t prefix = Prefixes[nextByte]; + State nextState = Prefix; + if(prefix) + consumeByte(); + switch(prefix) + { + //Operand size override prefixes + case OperandSizeOverride: + DPRINTF(Predecoder, "Found operand size override prefix.\n"); + break; + case AddressSizeOverride: + DPRINTF(Predecoder, "Found address size override prefix.\n"); + break; + //Segment override prefixes + case CSOverride: + DPRINTF(Predecoder, "Found cs segment override.\n"); + break; + case DSOverride: + DPRINTF(Predecoder, "Found ds segment override.\n"); + break; + case ESOverride: + DPRINTF(Predecoder, "Found es segment override.\n"); + break; + case FSOverride: + DPRINTF(Predecoder, "Found fs segment override.\n"); + break; + case GSOverride: + DPRINTF(Predecoder, "Found gs segment override.\n"); + break; + case SSOverride: + DPRINTF(Predecoder, "Found ss segment override.\n"); + break; + case Lock: + DPRINTF(Predecoder, "Found lock prefix.\n"); + break; + case Rep: + DPRINTF(Predecoder, "Found rep prefix.\n"); + break; + case Repne: + DPRINTF(Predecoder, "Found repne prefix.\n"); + break; + case Rex: + DPRINTF(Predecoder, "Found Rex prefix %#x.\n", nextByte); + emi.rexPrefix = nextByte; + break; + case 0: + emi.numOpcodes = 0; + nextState = Opcode; + break; + default: + panic("Unrecognized prefix %#x\n", nextByte); + } + return nextState; + } + + //Load all the opcodes (currently up to 2) and then figure out + //what immediate and/or ModRM is needed. + Predecoder::State Predecoder::doOpcodeState(uint8_t nextByte) + { + State nextState = ErrorState; + emi.numOpcodes++; + //We can't handle 3+ byte opcodes right now + assert(emi.numOpcodes < 2); + consumeByte(); + if(nextByte == 0xf0) + { + nextState = Opcode; + DPRINTF(Predecoder, "Found two byte opcode.\n"); + } + else + { + DPRINTF(Predecoder, "Found opcode %#x.\n", nextByte); + + //Prepare for any immediate/displacement we might need + immediateCollected = 0; + emi.immediate = 0; + displacementCollected = 0; + emi.displacement = 0; + + //Figure out how big of an immediate we'll retreive based + //on the opcode. + int immType = ImmediateType[ + emi.numOpcodes - 1][nextByte]; + if(0) //16 bit mode + immediateSize = ImmediateTypeToSize[0][immType]; + else if(!(emi.rexPrefix & 0x4)) //32 bit mode + immediateSize = ImmediateTypeToSize[1][immType]; + else //64 bit mode + immediateSize = ImmediateTypeToSize[2][immType]; + + //Determine what to expect next + if (UsesModRM[emi.numOpcodes - 1][nextByte]) { + nextState = ModRM; + } else if(immediateSize) { + nextState = Immediate; + } else { + emiIsReady = true; + nextState = Prefix; + } + } + return nextState; + } + + //Get the ModRM byte and determine what displacement, if any, there is. + //Also determine whether or not to get the SIB byte, displacement, or + //immediate next. + Predecoder::State Predecoder::doModRMState(uint8_t nextByte) + { + State nextState = ErrorState; + DPRINTF(Predecoder, "Found modrm byte %#x.\n", nextByte); + if (0) {//FIXME in 16 bit mode + //figure out 16 bit displacement size + if(nextByte & 0xC7 == 0x06 || + nextByte & 0xC0 == 0x80) + displacementSize = 2; + else if(nextByte & 0xC0 == 0x40) + displacementSize = 1; + else + displacementSize = 0; + } else { + //figure out 32/64 bit displacement size + if(nextByte & 0xC7 == 0x05 || + nextByte & 0xC0 == 0x80) + displacementSize = 4; + else if(nextByte & 0xC0 == 0x40) + displacementSize = 2; + else + displacementSize = 0; + } + //If there's an SIB, get that next. + //There is no SIB in 16 bit mode. + if(nextByte & 0x7 == 4 && + nextByte & 0xC0 != 0xC0) { + // && in 32/64 bit mode) + nextState = SIB; + } else if(displacementSize) { + nextState = Displacement; + } else if(immediateSize) { + nextState = Immediate; + } else { + emiIsReady = true; + nextState = Prefix; + } + //The ModRM byte is consumed no matter what + consumeByte(); + return nextState; + } + + //Get the SIB byte. We don't do anything with it at this point, other + //than storing it in the ExtMachInst. Determine if we need to get a + //displacement or immediate next. + Predecoder::State Predecoder::doSIBState(uint8_t nextByte) + { + State nextState = ErrorState; + DPRINTF(Predecoder, "Found SIB byte %#x.\n", nextByte); + consumeByte(); + if(displacementSize) { + nextState = Displacement; + } else if(immediateSize) { + nextState = Immediate; + } else { + emiIsReady = true; + nextState = Prefix; + } + return nextState; + } + + //Gather up the displacement, or at least as much of it + //as we can get. + Predecoder::State Predecoder::doDisplacementState() + { + State nextState = ErrorState; + + getImmediate(displacementCollected, + emi.displacement, + displacementSize); + + DPRINTF(Predecoder, "Collecting %d byte displacement, got %d bytes.\n", + displacementSize, displacementCollected); + + if(displacementSize == displacementCollected) { + //Sign extend the displacement + switch(displacementSize) + { + case 1: + emi.displacement = sext<8>(emi.displacement); + break; + case 2: + emi.displacement = sext<16>(emi.displacement); + break; + case 4: + emi.displacement = sext<32>(emi.displacement); + break; + default: + panic("Undefined displacement size!\n"); + } + DPRINTF(Predecoder, "Collected displacement %#x.\n", + emi.displacement); + if(immediateSize) { + nextState = Immediate; + } else { + emiIsReady = true; + nextState = Prefix; + } + } + else + nextState = Displacement; + return nextState; + } + + //Gather up the immediate, or at least as much of it + //as we can get + Predecoder::State Predecoder::doImmediateState() + { + State nextState = ErrorState; + + getImmediate(immediateCollected, + emi.immediate, + immediateSize); + + DPRINTF(Predecoder, "Collecting %d byte immediate, got %d bytes.\n", + immediateSize, immediateCollected); + + if(immediateSize == immediateCollected) + { + DPRINTF(Predecoder, "Collected immediate %#x.\n", + emi.immediate); + emiIsReady = true; + nextState = Prefix; + } + else + nextState = Immediate; + return nextState; + } +} |