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-/*
- * Copyright (c) 2007-2008 The Hewlett-Packard Development Company
- * All rights reserved.
- *
- * The license below extends only to copyright in the software and shall
- * not be construed as granting a license to any other intellectual
- * property including but not limited to intellectual property relating
- * to a hardware implementation of the functionality of the software
- * licensed hereunder. You may use the software subject to the license
- * terms below provided that you ensure that this notice is replicated
- * unmodified and in its entirety in all distributions of the software,
- * modified or unmodified, in source code or in binary form.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met: 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 holders nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * 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/regs/misc.hh"
-#include "arch/x86/predecoder.hh"
-#include "base/misc.hh"
-#include "base/trace.hh"
-#include "base/types.hh"
-#include "cpu/thread_context.hh"
-#include "debug/Predecoder.hh"
-
-namespace X86ISA
-{
- void Predecoder::doReset()
- {
- origPC = basePC + offset;
- DPRINTF(Predecoder, "Setting origPC to %#x\n", origPC);
- emi.rex = 0;
- emi.legacy = 0;
- emi.opcode.num = 0;
- emi.opcode.op = 0;
- emi.opcode.prefixA = emi.opcode.prefixB = 0;
-
- immediateCollected = 0;
- emi.immediate = 0;
- emi.displacement = 0;
- emi.dispSize = 0;
-
- emi.modRM = 0;
- emi.sib = 0;
- m5Reg = tc->readMiscRegNoEffect(MISCREG_M5_REG);
- emi.mode.mode = m5Reg.mode;
- emi.mode.submode = m5Reg.submode;
- }
-
- 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 ResetState:
- doReset();
- state = PrefixState;
- case PrefixState:
- state = doPrefixState(nextByte);
- break;
- case OpcodeState:
- state = doOpcodeState(nextByte);
- break;
- case ModRMState:
- state = doModRMState(nextByte);
- break;
- case SIBState:
- state = doSIBState(nextByte);
- break;
- case DisplacementState:
- state = doDisplacementState();
- break;
- case ImmediateState:
- 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 = PrefixState;
- // REX prefixes are only recognized in 64 bit mode.
- if (prefix == RexPrefix && emi.mode.submode != SixtyFourBitMode)
- prefix = 0;
- if (prefix)
- consumeByte();
- switch(prefix)
- {
- //Operand size override prefixes
- case OperandSizeOverride:
- DPRINTF(Predecoder, "Found operand size override prefix.\n");
- emi.legacy.op = true;
- break;
- case AddressSizeOverride:
- DPRINTF(Predecoder, "Found address size override prefix.\n");
- emi.legacy.addr = true;
- break;
- //Segment override prefixes
- case CSOverride:
- case DSOverride:
- case ESOverride:
- case FSOverride:
- case GSOverride:
- case SSOverride:
- DPRINTF(Predecoder, "Found segment override.\n");
- emi.legacy.seg = prefix;
- break;
- case Lock:
- DPRINTF(Predecoder, "Found lock prefix.\n");
- emi.legacy.lock = true;
- break;
- case Rep:
- DPRINTF(Predecoder, "Found rep prefix.\n");
- emi.legacy.rep = true;
- break;
- case Repne:
- DPRINTF(Predecoder, "Found repne prefix.\n");
- emi.legacy.repne = true;
- break;
- case RexPrefix:
- DPRINTF(Predecoder, "Found Rex prefix %#x.\n", nextByte);
- emi.rex = nextByte;
- break;
- case 0:
- nextState = OpcodeState;
- 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.opcode.num++;
- //We can't handle 3+ byte opcodes right now
- assert(emi.opcode.num < 4);
- consumeByte();
- if(emi.opcode.num == 1 && nextByte == 0x0f)
- {
- nextState = OpcodeState;
- DPRINTF(Predecoder, "Found two byte opcode.\n");
- emi.opcode.prefixA = nextByte;
- }
- else if(emi.opcode.num == 2 && (nextByte == 0x38 || nextByte == 0x3A))
- {
- nextState = OpcodeState;
- DPRINTF(Predecoder, "Found three byte opcode.\n");
- emi.opcode.prefixB = nextByte;
- }
- else
- {
- DPRINTF(Predecoder, "Found opcode %#x.\n", nextByte);
- emi.opcode.op = nextByte;
-
- //Figure out the effective operand size. This can be overriden to
- //a fixed value at the decoder level.
- int logOpSize;
- if (emi.rex.w)
- logOpSize = 3; // 64 bit operand size
- else if (emi.legacy.op)
- logOpSize = m5Reg.altOp;
- else
- logOpSize = m5Reg.defOp;
-
- //Set the actual op size
- emi.opSize = 1 << logOpSize;
-
- //Figure out the effective address size. This can be overriden to
- //a fixed value at the decoder level.
- int logAddrSize;
- if(emi.legacy.addr)
- logAddrSize = m5Reg.altAddr;
- else
- logAddrSize = m5Reg.defAddr;
-
- //Set the actual address size
- emi.addrSize = 1 << logAddrSize;
-
- //Figure out the effective stack width. This can be overriden to
- //a fixed value at the decoder level.
- emi.stackSize = 1 << m5Reg.stack;
-
- //Figure out how big of an immediate we'll retreive based
- //on the opcode.
- int immType = ImmediateType[emi.opcode.num - 1][nextByte];
- if (emi.opcode.num == 1 && nextByte >= 0xA0 && nextByte <= 0xA3)
- immediateSize = SizeTypeToSize[logAddrSize - 1][immType];
- else
- immediateSize = SizeTypeToSize[logOpSize - 1][immType];
-
- //Determine what to expect next
- if (UsesModRM[emi.opcode.num - 1][nextByte]) {
- nextState = ModRMState;
- } else {
- if(immediateSize) {
- nextState = ImmediateState;
- } else {
- emiIsReady = true;
- nextState = ResetState;
- }
- }
- }
- 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;
- ModRM modRM;
- modRM = nextByte;
- DPRINTF(Predecoder, "Found modrm byte %#x.\n", nextByte);
- if (m5Reg.defOp == 1) {
- //figure out 16 bit displacement size
- if ((modRM.mod == 0 && modRM.rm == 6) || modRM.mod == 2)
- displacementSize = 2;
- else if (modRM.mod == 1)
- displacementSize = 1;
- else
- displacementSize = 0;
- } else {
- //figure out 32/64 bit displacement size
- if ((modRM.mod == 0 && modRM.rm == 5) || modRM.mod == 2)
- displacementSize = 4;
- else if (modRM.mod == 1)
- displacementSize = 1;
- else
- displacementSize = 0;
- }
-
- // The "test" instruction in group 3 needs an immediate, even though
- // the other instructions with the same actual opcode don't.
- if (emi.opcode.num == 1 && (modRM.reg & 0x6) == 0) {
- if (emi.opcode.op == 0xF6)
- immediateSize = 1;
- else if (emi.opcode.op == 0xF7)
- immediateSize = (emi.opSize == 8) ? 4 : emi.opSize;
- }
-
- //If there's an SIB, get that next.
- //There is no SIB in 16 bit mode.
- if (modRM.rm == 4 && modRM.mod != 3) {
- // && in 32/64 bit mode)
- nextState = SIBState;
- } else if(displacementSize) {
- nextState = DisplacementState;
- } else if(immediateSize) {
- nextState = ImmediateState;
- } else {
- emiIsReady = true;
- nextState = ResetState;
- }
- //The ModRM byte is consumed no matter what
- consumeByte();
- emi.modRM = modRM;
- 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;
- emi.sib = nextByte;
- DPRINTF(Predecoder, "Found SIB byte %#x.\n", nextByte);
- consumeByte();
- if (emi.modRM.mod == 0 && emi.sib.base == 5)
- displacementSize = 4;
- if (displacementSize) {
- nextState = DisplacementState;
- } else if(immediateSize) {
- nextState = ImmediateState;
- } else {
- emiIsReady = true;
- nextState = ResetState;
- }
- 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(immediateCollected,
- emi.displacement,
- displacementSize);
-
- DPRINTF(Predecoder, "Collecting %d byte displacement, got %d bytes.\n",
- displacementSize, immediateCollected);
-
- if(displacementSize == immediateCollected) {
- //Reset this for other immediates.
- immediateCollected = 0;
- //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 = ImmediateState;
- } else {
- emiIsReady = true;
- nextState = ResetState;
- }
-
- emi.dispSize = displacementSize;
- }
- else
- nextState = DisplacementState;
- 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)
- {
- //Reset this for other immediates.
- immediateCollected = 0;
-
- //XXX Warning! The following is an observed pattern and might
- //not always be true!
-
- //Instructions which use 64 bit operands but 32 bit immediates
- //need to have the immediate sign extended to 64 bits.
- //Instructions which use true 64 bit immediates won't be
- //affected, and instructions that use true 32 bit immediates
- //won't notice.
- switch(immediateSize)
- {
- case 4:
- emi.immediate = sext<32>(emi.immediate);
- break;
- case 1:
- emi.immediate = sext<8>(emi.immediate);
- }
-
- DPRINTF(Predecoder, "Collected immediate %#x.\n",
- emi.immediate);
- emiIsReady = true;
- nextState = ResetState;
- }
- else
- nextState = ImmediateState;
- return nextState;
- }
-}
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