0ef3dcc27b
This patch updates the x86 decoder so that it can decode instructions with vex prefix. It also updates the isa with opcodes from vex opcode maps 1, 2 and 3. Note that none of the instructions have been implemented yet. The implementations would be provided in due course of time.
702 lines
20 KiB
C++
702 lines
20 KiB
C++
/*
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* Copyright (c) 2011 Google
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Gabe Black
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*/
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#include "arch/x86/decoder.hh"
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#include "arch/x86/regs/misc.hh"
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#include "base/misc.hh"
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#include "base/trace.hh"
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#include "base/types.hh"
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#include "debug/Decoder.hh"
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namespace X86ISA
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{
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Decoder::State
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Decoder::doResetState()
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{
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origPC = basePC + offset;
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DPRINTF(Decoder, "Setting origPC to %#x\n", origPC);
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instBytes = &decodePages->lookup(origPC);
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chunkIdx = 0;
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emi.rex = 0;
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emi.legacy = 0;
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emi.vex = 0;
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emi.opcode.type = BadOpcode;
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emi.opcode.op = 0;
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immediateCollected = 0;
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emi.immediate = 0;
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emi.displacement = 0;
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emi.dispSize = 0;
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emi.modRM = 0;
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emi.sib = 0;
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if (instBytes->si) {
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return FromCacheState;
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} else {
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instBytes->chunks.clear();
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return PrefixState;
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}
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}
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void
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Decoder::process()
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{
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//This function drives the decoder state machine.
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//Some sanity checks. You shouldn't try to process more bytes if
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//there aren't any, and you shouldn't overwrite an already
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//decoder ExtMachInst.
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assert(!outOfBytes);
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assert(!instDone);
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if (state == ResetState)
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state = doResetState();
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if (state == FromCacheState) {
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state = doFromCacheState();
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} else {
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instBytes->chunks.push_back(fetchChunk);
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}
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//While there's still something to do...
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while (!instDone && !outOfBytes) {
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uint8_t nextByte = getNextByte();
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switch (state) {
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case PrefixState:
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state = doPrefixState(nextByte);
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break;
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case TwoByteVexState:
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state = doTwoByteVexState(nextByte);
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break;
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case ThreeByteVexFirstState:
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state = doThreeByteVexFirstState(nextByte);
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break;
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case ThreeByteVexSecondState:
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state = doThreeByteVexSecondState(nextByte);
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break;
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case OneByteOpcodeState:
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state = doOneByteOpcodeState(nextByte);
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break;
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case TwoByteOpcodeState:
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state = doTwoByteOpcodeState(nextByte);
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break;
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case ThreeByte0F38OpcodeState:
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state = doThreeByte0F38OpcodeState(nextByte);
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break;
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case ThreeByte0F3AOpcodeState:
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state = doThreeByte0F3AOpcodeState(nextByte);
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break;
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case ModRMState:
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state = doModRMState(nextByte);
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break;
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case SIBState:
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state = doSIBState(nextByte);
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break;
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case DisplacementState:
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state = doDisplacementState();
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break;
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case ImmediateState:
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state = doImmediateState();
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break;
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case ErrorState:
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panic("Went to the error state in the decoder.\n");
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default:
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panic("Unrecognized state! %d\n", state);
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}
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}
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}
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Decoder::State
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Decoder::doFromCacheState()
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{
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DPRINTF(Decoder, "Looking at cache state.\n");
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if ((fetchChunk & instBytes->masks[chunkIdx]) !=
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instBytes->chunks[chunkIdx]) {
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DPRINTF(Decoder, "Decode cache miss.\n");
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// The chached chunks didn't match what was fetched. Fall back to the
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// predecoder.
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instBytes->chunks[chunkIdx] = fetchChunk;
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instBytes->chunks.resize(chunkIdx + 1);
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instBytes->si = NULL;
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chunkIdx = 0;
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fetchChunk = instBytes->chunks[0];
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offset = origPC % sizeof(MachInst);
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basePC = origPC - offset;
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return PrefixState;
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} else if (chunkIdx == instBytes->chunks.size() - 1) {
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// We matched the cache, so use its value.
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instDone = true;
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offset = instBytes->lastOffset;
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if (offset == sizeof(MachInst))
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outOfBytes = true;
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return ResetState;
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} else {
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// We matched so far, but need to check more chunks.
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chunkIdx++;
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outOfBytes = true;
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return FromCacheState;
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}
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}
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//Either get a prefix and record it in the ExtMachInst, or send the
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//state machine on to get the opcode(s).
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Decoder::State
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Decoder::doPrefixState(uint8_t nextByte)
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{
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uint8_t prefix = Prefixes[nextByte];
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State nextState = PrefixState;
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// REX prefixes are only recognized in 64 bit mode.
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if (prefix == RexPrefix && emi.mode.submode != SixtyFourBitMode)
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prefix = 0;
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if (prefix)
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consumeByte();
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switch(prefix)
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{
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//Operand size override prefixes
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case OperandSizeOverride:
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DPRINTF(Decoder, "Found operand size override prefix.\n");
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emi.legacy.op = true;
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break;
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case AddressSizeOverride:
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DPRINTF(Decoder, "Found address size override prefix.\n");
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emi.legacy.addr = true;
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break;
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//Segment override prefixes
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case CSOverride:
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case DSOverride:
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case ESOverride:
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case FSOverride:
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case GSOverride:
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case SSOverride:
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DPRINTF(Decoder, "Found segment override.\n");
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emi.legacy.seg = prefix;
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break;
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case Lock:
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DPRINTF(Decoder, "Found lock prefix.\n");
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emi.legacy.lock = true;
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break;
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case Rep:
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DPRINTF(Decoder, "Found rep prefix.\n");
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emi.legacy.rep = true;
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break;
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case Repne:
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DPRINTF(Decoder, "Found repne prefix.\n");
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emi.legacy.repne = true;
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break;
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case RexPrefix:
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DPRINTF(Decoder, "Found Rex prefix %#x.\n", nextByte);
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emi.rex = nextByte;
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break;
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case Vex2Prefix:
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DPRINTF(Decoder, "Found VEX two-byte prefix %#x.\n", nextByte);
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emi.vex.zero = nextByte;
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nextState = TwoByteVexState;
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break;
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case Vex3Prefix:
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DPRINTF(Decoder, "Found VEX three-byte prefix %#x.\n", nextByte);
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emi.vex.zero = nextByte;
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nextState = ThreeByteVexFirstState;
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break;
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case 0:
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nextState = OneByteOpcodeState;
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break;
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default:
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panic("Unrecognized prefix %#x\n", nextByte);
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}
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return nextState;
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}
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Decoder::State
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Decoder::doTwoByteVexState(uint8_t nextByte)
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{
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assert(emi.vex.zero == 0xc5);
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consumeByte();
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TwoByteVex tbe = 0;
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tbe.first = nextByte;
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emi.vex.first.r = tbe.first.r;
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emi.vex.first.x = 1;
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emi.vex.first.b = 1;
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emi.vex.first.map_select = 1;
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emi.vex.second.w = 0;
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emi.vex.second.vvvv = tbe.first.vvvv;
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emi.vex.second.l = tbe.first.l;
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emi.vex.second.pp = tbe.first.pp;
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emi.opcode.type = Vex;
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return OneByteOpcodeState;
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}
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Decoder::State
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Decoder::doThreeByteVexFirstState(uint8_t nextByte)
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{
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consumeByte();
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emi.vex.first = nextByte;
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return ThreeByteVexSecondState;
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}
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Decoder::State
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Decoder::doThreeByteVexSecondState(uint8_t nextByte)
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{
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consumeByte();
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emi.vex.second = nextByte;
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emi.opcode.type = Vex;
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return OneByteOpcodeState;
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}
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// Load the first opcode byte. Determine if there are more opcode bytes, and
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// if not, what immediate and/or ModRM is needed.
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Decoder::State
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Decoder::doOneByteOpcodeState(uint8_t nextByte)
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{
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State nextState = ErrorState;
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consumeByte();
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if (emi.vex.zero != 0) {
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DPRINTF(Decoder, "Found VEX opcode %#x.\n", nextByte);
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emi.opcode.op = nextByte;
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const uint8_t opcode_map = emi.vex.first.map_select;
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nextState = processExtendedOpcode(ImmediateTypeVex[opcode_map]);
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} else if (nextByte == 0x0f) {
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nextState = TwoByteOpcodeState;
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DPRINTF(Decoder, "Found opcode escape byte %#x.\n", nextByte);
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} else {
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DPRINTF(Decoder, "Found one byte opcode %#x.\n", nextByte);
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emi.opcode.type = OneByteOpcode;
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emi.opcode.op = nextByte;
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nextState = processOpcode(ImmediateTypeOneByte, UsesModRMOneByte,
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nextByte >= 0xA0 && nextByte <= 0xA3);
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}
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return nextState;
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}
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// Load the second opcode byte. Determine if there are more opcode bytes, and
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// if not, what immediate and/or ModRM is needed.
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Decoder::State
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Decoder::doTwoByteOpcodeState(uint8_t nextByte)
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{
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State nextState = ErrorState;
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consumeByte();
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if (nextByte == 0x38) {
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nextState = ThreeByte0F38OpcodeState;
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DPRINTF(Decoder, "Found opcode escape byte %#x.\n", nextByte);
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} else if (nextByte == 0x3a) {
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nextState = ThreeByte0F3AOpcodeState;
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DPRINTF(Decoder, "Found opcode escape byte %#x.\n", nextByte);
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} else {
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DPRINTF(Decoder, "Found two byte opcode %#x.\n", nextByte);
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emi.opcode.type = TwoByteOpcode;
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emi.opcode.op = nextByte;
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nextState = processOpcode(ImmediateTypeTwoByte, UsesModRMTwoByte);
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}
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return nextState;
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}
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// Load the third opcode byte and determine what immediate and/or ModRM is
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// needed.
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Decoder::State
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Decoder::doThreeByte0F38OpcodeState(uint8_t nextByte)
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{
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consumeByte();
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DPRINTF(Decoder, "Found three byte 0F38 opcode %#x.\n", nextByte);
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emi.opcode.type = ThreeByte0F38Opcode;
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emi.opcode.op = nextByte;
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return processOpcode(ImmediateTypeThreeByte0F38, UsesModRMThreeByte0F38);
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}
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// Load the third opcode byte and determine what immediate and/or ModRM is
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// needed.
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Decoder::State
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Decoder::doThreeByte0F3AOpcodeState(uint8_t nextByte)
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{
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consumeByte();
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DPRINTF(Decoder, "Found three byte 0F3A opcode %#x.\n", nextByte);
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emi.opcode.type = ThreeByte0F3AOpcode;
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emi.opcode.op = nextByte;
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return processOpcode(ImmediateTypeThreeByte0F3A, UsesModRMThreeByte0F3A);
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}
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// Generic opcode processing which determines the immediate size, and whether
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// or not there's a modrm byte.
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Decoder::State
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Decoder::processOpcode(ByteTable &immTable, ByteTable &modrmTable,
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bool addrSizedImm)
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{
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State nextState = ErrorState;
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const uint8_t opcode = emi.opcode.op;
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//Figure out the effective operand size. This can be overriden to
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//a fixed value at the decoder level.
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int logOpSize;
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if (emi.rex.w)
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logOpSize = 3; // 64 bit operand size
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else if (emi.legacy.op)
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logOpSize = altOp;
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else
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logOpSize = defOp;
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//Set the actual op size
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emi.opSize = 1 << logOpSize;
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//Figure out the effective address size. This can be overriden to
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//a fixed value at the decoder level.
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int logAddrSize;
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if(emi.legacy.addr)
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logAddrSize = altAddr;
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else
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logAddrSize = defAddr;
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//Set the actual address size
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emi.addrSize = 1 << logAddrSize;
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//Figure out the effective stack width. This can be overriden to
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//a fixed value at the decoder level.
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emi.stackSize = 1 << stack;
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//Figure out how big of an immediate we'll retreive based
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//on the opcode.
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int immType = immTable[opcode];
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if (addrSizedImm)
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immediateSize = SizeTypeToSize[logAddrSize - 1][immType];
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else
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immediateSize = SizeTypeToSize[logOpSize - 1][immType];
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//Determine what to expect next
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if (modrmTable[opcode]) {
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nextState = ModRMState;
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} else {
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if(immediateSize) {
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nextState = ImmediateState;
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} else {
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instDone = true;
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nextState = ResetState;
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}
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}
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return nextState;
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}
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Decoder::State
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Decoder::processExtendedOpcode(ByteTable &immTable)
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{
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//Figure out the effective operand size. This can be overriden to
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//a fixed value at the decoder level.
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int logOpSize;
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if (emi.vex.second.w)
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logOpSize = 3; // 64 bit operand size
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else if (emi.vex.second.pp == 1)
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logOpSize = altOp;
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else
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logOpSize = defOp;
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//Set the actual op size
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emi.opSize = 1 << logOpSize;
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//Figure out the effective address size. This can be overriden to
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//a fixed value at the decoder level.
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int logAddrSize;
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if(emi.legacy.addr)
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logAddrSize = altAddr;
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else
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logAddrSize = defAddr;
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//Set the actual address size
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emi.addrSize = 1 << logAddrSize;
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//Figure out the effective stack width. This can be overriden to
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//a fixed value at the decoder level.
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emi.stackSize = 1 << stack;
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//Figure out how big of an immediate we'll retreive based
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//on the opcode.
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const uint8_t opcode = emi.opcode.op;
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if (emi.vex.zero == 0xc5 || emi.vex.zero == 0xc4) {
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int immType = immTable[opcode];
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// Assume 64-bit mode;
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immediateSize = SizeTypeToSize[2][immType];
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}
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if (opcode == 0x77) {
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instDone = true;
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return ResetState;
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}
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return ModRMState;
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}
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//Get the ModRM byte and determine what displacement, if any, there is.
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//Also determine whether or not to get the SIB byte, displacement, or
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//immediate next.
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Decoder::State
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Decoder::doModRMState(uint8_t nextByte)
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{
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State nextState = ErrorState;
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ModRM modRM = nextByte;
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DPRINTF(Decoder, "Found modrm byte %#x.\n", nextByte);
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if (defOp == 1) {
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//figure out 16 bit displacement size
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if ((modRM.mod == 0 && modRM.rm == 6) || modRM.mod == 2)
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displacementSize = 2;
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else if (modRM.mod == 1)
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displacementSize = 1;
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else
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displacementSize = 0;
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} else {
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//figure out 32/64 bit displacement size
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if ((modRM.mod == 0 && modRM.rm == 5) || modRM.mod == 2)
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displacementSize = 4;
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else if (modRM.mod == 1)
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displacementSize = 1;
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else
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displacementSize = 0;
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}
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// The "test" instruction in group 3 needs an immediate, even though
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// the other instructions with the same actual opcode don't.
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if (emi.opcode.type == OneByteOpcode && (modRM.reg & 0x6) == 0) {
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if (emi.opcode.op == 0xF6)
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immediateSize = 1;
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else if (emi.opcode.op == 0xF7)
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immediateSize = (emi.opSize == 8) ? 4 : emi.opSize;
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}
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//If there's an SIB, get that next.
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//There is no SIB in 16 bit mode.
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if (modRM.rm == 4 && modRM.mod != 3) {
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// && in 32/64 bit mode)
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nextState = SIBState;
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} else if(displacementSize) {
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nextState = DisplacementState;
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} else if(immediateSize) {
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nextState = ImmediateState;
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} else {
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instDone = true;
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nextState = ResetState;
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}
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//The ModRM byte is consumed no matter what
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consumeByte();
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emi.modRM = modRM;
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return nextState;
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}
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//Get the SIB byte. We don't do anything with it at this point, other
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//than storing it in the ExtMachInst. Determine if we need to get a
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//displacement or immediate next.
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Decoder::State
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Decoder::doSIBState(uint8_t nextByte)
|
|
{
|
|
State nextState = ErrorState;
|
|
emi.sib = nextByte;
|
|
DPRINTF(Decoder, "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 {
|
|
instDone = true;
|
|
nextState = ResetState;
|
|
}
|
|
return nextState;
|
|
}
|
|
|
|
//Gather up the displacement, or at least as much of it
|
|
//as we can get.
|
|
Decoder::State
|
|
Decoder::doDisplacementState()
|
|
{
|
|
State nextState = ErrorState;
|
|
|
|
getImmediate(immediateCollected,
|
|
emi.displacement,
|
|
displacementSize);
|
|
|
|
DPRINTF(Decoder, "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(Decoder, "Collected displacement %#x.\n",
|
|
emi.displacement);
|
|
if(immediateSize) {
|
|
nextState = ImmediateState;
|
|
} else {
|
|
instDone = 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
|
|
Decoder::State
|
|
Decoder::doImmediateState()
|
|
{
|
|
State nextState = ErrorState;
|
|
|
|
getImmediate(immediateCollected,
|
|
emi.immediate,
|
|
immediateSize);
|
|
|
|
DPRINTF(Decoder, "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(Decoder, "Collected immediate %#x.\n",
|
|
emi.immediate);
|
|
instDone = true;
|
|
nextState = ResetState;
|
|
}
|
|
else
|
|
nextState = ImmediateState;
|
|
return nextState;
|
|
}
|
|
|
|
Decoder::InstBytes Decoder::dummy;
|
|
Decoder::InstCacheMap Decoder::instCacheMap;
|
|
|
|
StaticInstPtr
|
|
Decoder::decode(ExtMachInst mach_inst, Addr addr)
|
|
{
|
|
DecodeCache::InstMap::iterator iter = instMap->find(mach_inst);
|
|
if (iter != instMap->end())
|
|
return iter->second;
|
|
|
|
StaticInstPtr si = decodeInst(mach_inst);
|
|
(*instMap)[mach_inst] = si;
|
|
return si;
|
|
}
|
|
|
|
StaticInstPtr
|
|
Decoder::decode(PCState &nextPC)
|
|
{
|
|
if (!instDone)
|
|
return NULL;
|
|
instDone = false;
|
|
updateNPC(nextPC);
|
|
|
|
StaticInstPtr &si = instBytes->si;
|
|
if (si)
|
|
return si;
|
|
|
|
// We didn't match in the AddrMap, but we still populated an entry. Fix
|
|
// up its byte masks.
|
|
const int chunkSize = sizeof(MachInst);
|
|
|
|
instBytes->lastOffset = offset;
|
|
|
|
Addr firstBasePC = basePC - (instBytes->chunks.size() - 1) * chunkSize;
|
|
Addr firstOffset = origPC - firstBasePC;
|
|
Addr totalSize = instBytes->lastOffset - firstOffset +
|
|
(instBytes->chunks.size() - 1) * chunkSize;
|
|
int start = firstOffset;
|
|
instBytes->masks.clear();
|
|
|
|
while (totalSize) {
|
|
int end = start + totalSize;
|
|
end = (chunkSize < end) ? chunkSize : end;
|
|
int size = end - start;
|
|
int idx = instBytes->masks.size();
|
|
|
|
MachInst maskVal = mask(size * 8) << (start * 8);
|
|
assert(maskVal);
|
|
|
|
instBytes->masks.push_back(maskVal);
|
|
instBytes->chunks[idx] &= instBytes->masks[idx];
|
|
totalSize -= size;
|
|
start = 0;
|
|
}
|
|
|
|
si = decode(emi, origPC);
|
|
return si;
|
|
}
|
|
|
|
}
|