419 lines
15 KiB
C++
419 lines
15 KiB
C++
/*
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* Copyright (c) 2007-2008 The Hewlett-Packard Development Company
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* All rights reserved.
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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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/regs/misc.hh"
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#include "arch/x86/predecoder.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 "cpu/thread_context.hh"
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#include "debug/Predecoder.hh"
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namespace X86ISA
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{
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void Predecoder::doReset()
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{
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origPC = basePC + offset;
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DPRINTF(Predecoder, "Setting origPC to %#x\n", origPC);
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emi.rex = 0;
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emi.legacy = 0;
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emi.opcode.num = 0;
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emi.opcode.op = 0;
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emi.opcode.prefixA = emi.opcode.prefixB = 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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m5Reg = tc->readMiscRegNoEffect(MISCREG_M5_REG);
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emi.mode.mode = m5Reg.mode;
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emi.mode.submode = m5Reg.submode;
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}
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void Predecoder::process()
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{
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//This function drives the predecoder 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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//predecoder ExtMachInst.
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assert(!outOfBytes);
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assert(!emiIsReady);
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//While there's still something to do...
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while(!emiIsReady && !outOfBytes)
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{
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uint8_t nextByte = getNextByte();
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switch(state)
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{
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case ResetState:
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doReset();
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state = PrefixState;
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case PrefixState:
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state = doPrefixState(nextByte);
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break;
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case OpcodeState:
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state = doOpcodeState(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 predecoder.\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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//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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Predecoder::State Predecoder::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(Predecoder, "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(Predecoder, "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(Predecoder, "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(Predecoder, "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(Predecoder, "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(Predecoder, "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(Predecoder, "Found Rex prefix %#x.\n", nextByte);
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emi.rex = nextByte;
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break;
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case 0:
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nextState = OpcodeState;
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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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//Load all the opcodes (currently up to 2) and then figure out
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//what immediate and/or ModRM is needed.
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Predecoder::State Predecoder::doOpcodeState(uint8_t nextByte)
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{
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State nextState = ErrorState;
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emi.opcode.num++;
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//We can't handle 3+ byte opcodes right now
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assert(emi.opcode.num < 4);
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consumeByte();
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if(emi.opcode.num == 1 && nextByte == 0x0f)
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{
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nextState = OpcodeState;
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DPRINTF(Predecoder, "Found two byte opcode.\n");
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emi.opcode.prefixA = nextByte;
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}
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else if(emi.opcode.num == 2 && (nextByte == 0x38 || nextByte == 0x3A))
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{
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nextState = OpcodeState;
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DPRINTF(Predecoder, "Found three byte opcode.\n");
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emi.opcode.prefixB = nextByte;
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}
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else
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{
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DPRINTF(Predecoder, "Found opcode %#x.\n", nextByte);
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emi.opcode.op = nextByte;
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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 = m5Reg.altOp;
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else
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logOpSize = m5Reg.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 = m5Reg.altAddr;
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else
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logAddrSize = m5Reg.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 << m5Reg.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 = ImmediateType[emi.opcode.num - 1][nextByte];
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if (emi.opcode.num == 1 && nextByte >= 0xA0 && nextByte <= 0xA3)
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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 (UsesModRM[emi.opcode.num - 1][nextByte]) {
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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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emiIsReady = true;
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nextState = ResetState;
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}
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}
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}
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return nextState;
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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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Predecoder::State Predecoder::doModRMState(uint8_t nextByte)
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{
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State nextState = ErrorState;
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ModRM modRM;
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modRM = nextByte;
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DPRINTF(Predecoder, "Found modrm byte %#x.\n", nextByte);
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if (m5Reg.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.num == 1 && (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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emiIsReady = 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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Predecoder::State Predecoder::doSIBState(uint8_t nextByte)
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{
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State nextState = ErrorState;
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emi.sib = nextByte;
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DPRINTF(Predecoder, "Found SIB byte %#x.\n", nextByte);
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consumeByte();
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if (emi.modRM.mod == 0 && emi.sib.base == 5)
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displacementSize = 4;
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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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emiIsReady = true;
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nextState = ResetState;
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}
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return nextState;
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}
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//Gather up the displacement, or at least as much of it
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//as we can get.
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Predecoder::State Predecoder::doDisplacementState()
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{
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State nextState = ErrorState;
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getImmediate(immediateCollected,
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emi.displacement,
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displacementSize);
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DPRINTF(Predecoder, "Collecting %d byte displacement, got %d bytes.\n",
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displacementSize, immediateCollected);
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if(displacementSize == immediateCollected) {
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//Reset this for other immediates.
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immediateCollected = 0;
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//Sign extend the displacement
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switch(displacementSize)
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{
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case 1:
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emi.displacement = sext<8>(emi.displacement);
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break;
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case 2:
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emi.displacement = sext<16>(emi.displacement);
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break;
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case 4:
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emi.displacement = sext<32>(emi.displacement);
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break;
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default:
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panic("Undefined displacement size!\n");
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}
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DPRINTF(Predecoder, "Collected displacement %#x.\n",
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emi.displacement);
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if(immediateSize) {
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nextState = ImmediateState;
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} else {
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emiIsReady = true;
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nextState = ResetState;
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}
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emi.dispSize = displacementSize;
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}
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else
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nextState = DisplacementState;
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return nextState;
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}
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//Gather up the immediate, or at least as much of it
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//as we can get
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Predecoder::State Predecoder::doImmediateState()
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{
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State nextState = ErrorState;
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getImmediate(immediateCollected,
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emi.immediate,
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immediateSize);
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DPRINTF(Predecoder, "Collecting %d byte immediate, got %d bytes.\n",
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immediateSize, immediateCollected);
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if(immediateSize == immediateCollected)
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{
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//Reset this for other immediates.
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immediateCollected = 0;
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//XXX Warning! The following is an observed pattern and might
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//not always be true!
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//Instructions which use 64 bit operands but 32 bit immediates
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//need to have the immediate sign extended to 64 bits.
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//Instructions which use true 64 bit immediates won't be
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//affected, and instructions that use true 32 bit immediates
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//won't notice.
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switch(immediateSize)
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{
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case 4:
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emi.immediate = sext<32>(emi.immediate);
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break;
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case 1:
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emi.immediate = sext<8>(emi.immediate);
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}
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DPRINTF(Predecoder, "Collected immediate %#x.\n",
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emi.immediate);
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emiIsReady = true;
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nextState = ResetState;
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}
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else
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nextState = ImmediateState;
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return nextState;
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}
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}
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