cpu_impl.hh

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/*
 * Copyright (c) 2011, 2016 ARM Limited
 * Copyright (c) 2013 Advanced Micro Devices, Inc.
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 *
 * 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
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 *
 * Copyright (c) 2006 The Regents of The University of Michigan
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 * met: redistributions of source code must retain the above copyright
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#ifndef __CPU_CHECKER_CPU_IMPL_HH__
#define __CPU_CHECKER_CPU_IMPL_HH__
 
#include <list>
#include <string>
 
#include "base/refcnt.hh"
#include "cpu/exetrace.hh"
#include "cpu/null_static_inst.hh"
#include "cpu/reg_class.hh"
#include "cpu/simple_thread.hh"
#include "cpu/static_inst.hh"
#include "cpu/thread_context.hh"
#include "cpu/checker/cpu.hh"
#include "debug/Checker.hh"
#include "sim/full_system.hh"
#include "sim/sim_object.hh"
#include "sim/stats.hh"
 
namespace gem5
{
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::advancePC(const Fault &fault)
{
    if (fault != NoFault) {
        curMacroStaticInst = nullStaticInstPtr;
        fault->invoke(tc, curStaticInst);
        thread->decoder->reset();
    } else {
        if (curStaticInst) {
            if (curStaticInst->isLastMicroop())
                curMacroStaticInst = nullStaticInstPtr;
            curStaticInst->advancePC(thread);
            DPRINTF(Checker, "Advancing PC to %s.\n", thread->pcState());
        }
    }
}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::handlePendingInt()
{
    DPRINTF(Checker, "IRQ detected at PC: %s with %d insts in buffer\n",
                     thread->pcState(), instList.size());
    DynInstPtr boundaryInst = NULL;
    if (!instList.empty()) {
        // Set the instructions as completed and verify as much as possible.
        DynInstPtr inst;
        typename std::list<DynInstPtr>::iterator itr;
 
        for (itr = instList.begin(); itr != instList.end(); itr++) {
            (*itr)->setCompleted();
        }
 
        inst = instList.front();
        boundaryInst = instList.back();
        verify(inst); // verify the instructions
        inst = NULL;
    }
    if ((!boundaryInst && curMacroStaticInst &&
          curStaticInst->isDelayedCommit() &&
          !curStaticInst->isLastMicroop()) ||
        (boundaryInst && boundaryInst->isDelayedCommit() &&
         !boundaryInst->isLastMicroop())) {
        panic("%lli: Trying to take an interrupt in middle of "
              "a non-interuptable instruction!", curTick());
    }
    boundaryInst = NULL;
    thread->decoder->reset();
    curMacroStaticInst = nullStaticInstPtr;
}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::verify(const DynInstPtr &completed_inst)
{
    DynInstPtr inst;
 
    // Make sure serializing instructions are actually
    // seen as serializing to commit. instList should be
    // empty in these cases.
    if ((completed_inst->isSerializing() ||
        completed_inst->isSerializeBefore()) &&
        (!instList.empty() ?
         (instList.front()->seqNum != completed_inst->seqNum) : 0)) {
        panic("%lli: Instruction sn:%lli at PC %s is serializing before but is"
              " entering instList with other instructions\n", curTick(),
              completed_inst->seqNum, completed_inst->pcState());
    }
 
    // Either check this instruction, or add it to a list of
    // instructions waiting to be checked.  Instructions must be
    // checked in program order, so if a store has committed yet not
    // completed, there may be some instructions that are waiting
    // behind it that have completed and must be checked.
    if (!instList.empty()) {
        if (youngestSN < completed_inst->seqNum) {
            DPRINTF(Checker, "Adding instruction [sn:%lli] PC:%s to list\n",
                    completed_inst->seqNum, completed_inst->pcState());
            instList.push_back(completed_inst);
            youngestSN = completed_inst->seqNum;
        }
 
        if (!instList.front()->isCompleted()) {
            return;
        } else {
            inst = instList.front();
            instList.pop_front();
        }
    } else {
        if (!completed_inst->isCompleted()) {
            if (youngestSN < completed_inst->seqNum) {
                DPRINTF(Checker, "Adding instruction [sn:%lli] PC:%s to list\n",
                        completed_inst->seqNum, completed_inst->pcState());
                instList.push_back(completed_inst);
                youngestSN = completed_inst->seqNum;
            }
            return;
        } else {
            if (youngestSN < completed_inst->seqNum) {
                inst = completed_inst;
                youngestSN = completed_inst->seqNum;
            } else {
                return;
            }
        }
    }
 
    // Make sure a serializing instruction is actually seen as
    // serializing. instList should be empty here
    if (inst->isSerializeAfter() && !instList.empty()) {
        panic("%lli: Instruction sn:%lli at PC %s is serializing after but is"
             " exiting instList with other instructions\n", curTick(),
             completed_inst->seqNum, completed_inst->pcState());
    }
    unverifiedInst = inst;
    inst = NULL;
 
    auto &decoder = thread->decoder;
    const Addr pc_mask = decoder->pcMask();
 
    // Try to check all instructions that are completed, ending if we
    // run out of instructions to check or if an instruction is not
    // yet completed.
    while (1) {
        DPRINTF(Checker, "Processing instruction [sn:%lli] PC:%s.\n",
                unverifiedInst->seqNum, unverifiedInst->pcState());
        unverifiedReq = NULL;
        unverifiedReq = unverifiedInst->reqToVerify;
        unverifiedMemData = unverifiedInst->memData;
        // Make sure results queue is empty
        while (!result.empty()) {
            result.pop();
        }
        baseStats.numCycles++;
 
        Fault fault = NoFault;
 
        // Check if any recent PC changes match up with anything we
        // expect to happen.  This is mostly to check if traps or
        // PC-based events have occurred in both the checker and CPU.
        if (changedPC) {
            DPRINTF(Checker, "Changed PC recently to %s\n",
                    thread->pcState());
            if (willChangePC) {
                if (*newPCState == thread->pcState()) {
                    DPRINTF(Checker, "Changed PC matches expected PC\n");
                } else {
                    warn("%lli: Changed PC does not match expected PC, "
                         "changed: %s, expected: %s",
                         curTick(), thread->pcState(), *newPCState);
                    CheckerCPU::handleError();
                }
                willChangePC = false;
            }
            changedPC = false;
        }
 
        // Try to fetch the instruction
        uint64_t fetchOffset = 0;
        bool fetchDone = false;
        while (!fetchDone) {
            Addr fetch_PC = thread->pcState().instAddr();
            fetch_PC = (fetch_PC & pc_mask) + fetchOffset;
 
            // If not in the middle of a macro instruction
            if (!curMacroStaticInst) {
                // set up memory request for instruction fetch
                auto mem_req = std::make_shared<Request>(
                    fetch_PC, decoder->moreBytesSize(), 0, requestorId,
                    fetch_PC, thread->contextId());
 
                mem_req->setVirt(fetch_PC, decoder->moreBytesSize(),
                                 Request::INST_FETCH, requestorId,
                                 thread->pcState().instAddr());
 
                fault = mmu->translateFunctional(
                    mem_req, tc, BaseMMU::Execute);
 
                if (fault != NoFault) {
                    if (unverifiedInst->getFault() == NoFault) {
                        // In this case the instruction was not a dummy
                        // instruction carrying an ITB fault.  In the single
                        // threaded case the ITB should still be able to
                        // translate this instruction; in the SMT case it's
                        // possible that its ITB entry was kicked out.
                        warn("%lli: Instruction PC %s was not found in the "
                             "ITB!", curTick(), thread->pcState());
                        handleError(unverifiedInst);
 
                        // go to the next instruction
                        advancePC(NoFault);
 
                        // Give up on an ITB fault..
                        unverifiedInst = NULL;
                        return;
                    } else {
                        // The instruction is carrying an ITB fault.  Handle
                        // the fault and see if our results match the CPU on
                        // the next tick().
                        fault = unverifiedInst->getFault();
                        break;
                    }
                } else {
                    PacketPtr pkt = new Packet(mem_req, MemCmd::ReadReq);
 
                    pkt->dataStatic(decoder->moreBytesPtr());
                    icachePort->sendFunctional(pkt);
 
                    delete pkt;
                }
            }
 
            if (fault == NoFault) {
                std::unique_ptr<PCStateBase> pc_state(
                        thread->pcState().clone());
 
                if (isRomMicroPC(pc_state->microPC())) {
                    fetchDone = true;
                    curStaticInst = decoder->fetchRomMicroop(
                            pc_state->microPC(), nullptr);
                } else if (!curMacroStaticInst) {
                    //We're not in the middle of a macro instruction
                    StaticInstPtr instPtr = nullptr;
 
                    //Predecode, ie bundle up an ExtMachInst
                    //If more fetch data is needed, pass it in.
                    Addr fetch_pc =
                        (pc_state->instAddr() & pc_mask) + fetchOffset;
                    decoder->moreBytes(*pc_state, fetch_pc);
 
                    //If an instruction is ready, decode it.
                    //Otherwise, we'll have to fetch beyond the
                    //memory chunk at the current pc.
                    if (decoder->instReady()) {
                        fetchDone = true;
                        instPtr = decoder->decode(*pc_state);
                        thread->pcState(*pc_state);
                    } else {
                        fetchDone = false;
                        fetchOffset += decoder->moreBytesSize();
                    }
 
                    //If we decoded an instruction and it's microcoded,
                    //start pulling out micro ops
                    if (instPtr && instPtr->isMacroop()) {
                        curMacroStaticInst = instPtr;
                        curStaticInst =
                            instPtr->fetchMicroop(pc_state->microPC());
                    } else {
                        curStaticInst = instPtr;
                    }
                } else {
                    // Read the next micro op from the macro-op
                    curStaticInst =
                        curMacroStaticInst->fetchMicroop(pc_state->microPC());
                    fetchDone = true;
                }
            }
        }
        // reset decoder on Checker
        decoder->reset();
 
        // Check Checker and CPU get same instruction, and record
        // any faults the CPU may have had.
        Fault unverifiedFault;
        if (fault == NoFault) {
            unverifiedFault = unverifiedInst->getFault();
 
            // Checks that the instruction matches what we expected it to be.
            // Checks both the machine instruction and the PC.
            validateInst(unverifiedInst);
        }
 
        // keep an instruction count
        numInst++;
 
 
        // Either the instruction was a fault and we should process the fault,
        // or we should just go ahead execute the instruction.  This assumes
        // that the instruction is properly marked as a fault.
        if (fault == NoFault) {
            // Execute Checker instruction and trace
            if (!unverifiedInst->isUnverifiable()) {
                trace::InstRecord *traceData = tracer->getInstRecord(curTick(),
                                                           tc,
                                                           curStaticInst,
                                                           pcState(),
                                                           curMacroStaticInst);
                fault = curStaticInst->execute(this, traceData);
                if (traceData) {
                    traceData->dump();
                    delete traceData;
                }
            }
 
            if (fault == NoFault && unverifiedFault == NoFault) {
                // Checks to make sure instrution results are correct.
                validateExecution(unverifiedInst);
 
                if (curStaticInst->isLoad()) {
                    ++numLoad;
                }
            } else if (fault != NoFault && unverifiedFault == NoFault) {
                panic("%lli: sn: %lli at PC: %s took a fault in checker "
                      "but not in driver CPU\n", curTick(),
                      unverifiedInst->seqNum, unverifiedInst->pcState());
            } else if (fault == NoFault && unverifiedFault != NoFault) {
                panic("%lli: sn: %lli at PC: %s took a fault in driver "
                      "CPU but not in checker\n", curTick(),
                      unverifiedInst->seqNum, unverifiedInst->pcState());
            }
        }
 
        // Take any faults here
        if (fault != NoFault) {
            if (FullSystem) {
                fault->invoke(tc, curStaticInst);
                willChangePC = true;
                set(newPCState, thread->pcState());
                DPRINTF(Checker, "Fault, PC is now %s\n", *newPCState);
                curMacroStaticInst = nullStaticInstPtr;
            }
        } else {
           advancePC(fault);
        }
 
        if (FullSystem) {
            // @todo: Determine if these should happen only if the
            // instruction hasn't faulted.  In the SimpleCPU case this may
            // not be true, but in the O3 case this may be true.
            Addr oldpc;
            int count = 0;
            do {
                oldpc = thread->pcState().instAddr();
                thread->pcEventQueue.service(oldpc, tc);
                count++;
            } while (oldpc != thread->pcState().instAddr());
            if (count > 1) {
                willChangePC = true;
                set(newPCState, thread->pcState());
                DPRINTF(Checker, "PC Event, PC is now %s\n", *newPCState);
            }
        }
 
        // @todo:  Optionally can check all registers. (Or just those
        // that have been modified).
        validateState();
 
        // Continue verifying instructions if there's another completed
        // instruction waiting to be verified.
        if (instList.empty()) {
            break;
        } else if (instList.front()->isCompleted()) {
            unverifiedInst = NULL;
            unverifiedInst = instList.front();
            instList.pop_front();
        } else {
            break;
        }
    }
    unverifiedInst = NULL;
}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::switchOut()
{
    instList.clear();
}
 
template <class DynInstPtr>
void Checker<DynInstPtr>::takeOverFrom(BaseCPU *oldCPU) {}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::validateInst(const DynInstPtr &inst)
{
    if (inst->pcState().instAddr() != thread->pcState().instAddr()) {
        warn("%lli: PCs do not match! Inst: %s, checker: %s",
             curTick(), inst->pcState(), thread->pcState());
        if (changedPC) {
            warn("%lli: Changed PCs recently, may not be an error",
                 curTick());
        } else {
            handleError(inst);
        }
    }
 
    if (curStaticInst != inst->staticInst) {
        warn("%lli: StaticInstPtrs don't match. (%s, %s).\n", curTick(),
                curStaticInst->getName(), inst->staticInst->getName());
    }
}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::validateExecution(const DynInstPtr &inst)
{
    InstResult checker_val;
    InstResult inst_val;
    int idx = -1;
    bool result_mismatch = false;
 
    if (inst->isUnverifiable()) {
        // Unverifiable instructions assume they were executed
        // properly by the CPU. Grab the result from the
        // instruction and write it to the register.
        copyResult(inst, InstResult(), idx);
    } else if (inst->numDestRegs() > 0 && !result.empty()) {
        DPRINTF(Checker, "Dest regs %d, number of checker dest regs %d\n",
                         inst->numDestRegs(), result.size());
        for (int i = 0; i < inst->numDestRegs() && !result.empty(); i++) {
            checker_val = result.front();
            result.pop();
            inst_val = inst->popResult();
            if (checker_val != inst_val) {
                result_mismatch = true;
                idx = i;
            }
        }
    } // Checker CPU checks all the saved results in the dyninst passed by
      // the cpu model being checked against the saved results present in
      // the static inst executed in the Checker.  Sometimes the number
      // of saved results differs between the dyninst and static inst, but
      // this is ok and not a bug.  May be worthwhile to try and correct this.
 
    if (result_mismatch) {
        warn("%lli: Instruction results (%i) do not match!  Inst: %s, "
             "checker: %s",
             curTick(), idx, inst_val.asString(), checker_val.asString());
 
        // It's useful to verify load values from memory, but in MP
        // systems the value obtained at execute may be different than
        // the value obtained at completion.  Similarly DMA can
        // present the same problem on even UP systems.  Thus there is
        // the option to only warn on loads having a result error.
        // The load/store queue in Detailed CPU can also cause problems
        // if load/store forwarding is allowed.
        if (inst->isLoad() && warnOnlyOnLoadError) {
            copyResult(inst, inst_val, idx);
        } else {
            handleError(inst);
        }
    }
 
    if (inst->pcState() != thread->pcState()) {
        warn("%lli: Instruction PCs do not match! Inst: %s, checker: %s",
             curTick(), inst->pcState(), thread->pcState());
        handleError(inst);
    }
 
    // Checking side effect registers can be difficult if they are not
    // checked simultaneously with the execution of the instruction.
    // This is because other valid instructions may have modified
    // these registers in the meantime, and their values are not
    // stored within the DynInst.
    while (!miscRegIdxs.empty()) {
        int misc_reg_idx = miscRegIdxs.front();
        miscRegIdxs.pop();
 
        if (inst->tcBase()->readMiscRegNoEffect(misc_reg_idx) !=
            thread->readMiscRegNoEffect(misc_reg_idx)) {
            warn("%lli: Misc reg idx %i (side effect) does not match! "
                 "Inst: %#x, checker: %#x",
                 curTick(), misc_reg_idx,
                 inst->tcBase()->readMiscRegNoEffect(misc_reg_idx),
                 thread->readMiscRegNoEffect(misc_reg_idx));
            handleError(inst);
        }
    }
}
 
 
// This function is weird, if it is called it means the Checker and
// O3 have diverged, so panic is called for now.  It may be useful
// to resynch states and continue if the divergence is a false positive
template <class DynInstPtr>
void
Checker<DynInstPtr>::validateState()
{
    if (updateThisCycle) {
        // Change this back to warn if divergences end up being false positives
        panic("%lli: Instruction PC %#x results didn't match up, copying all "
             "registers from main CPU", curTick(),
             unverifiedInst->pcState().instAddr());
 
        // Terribly convoluted way to make sure O3 model does not implode
        bool no_squash_from_TC = unverifiedInst->thread->noSquashFromTC;
        unverifiedInst->thread->noSquashFromTC = true;
 
        // Heavy-weight copying of all registers
        thread->copyArchRegs(unverifiedInst->tcBase());
        unverifiedInst->thread->noSquashFromTC = no_squash_from_TC;
 
        // Set curStaticInst to unverifiedInst->staticInst
        curStaticInst = unverifiedInst->staticInst;
        // Also advance the PC.  Hopefully no PC-based events happened.
        advancePC(NoFault);
        updateThisCycle = false;
    }
}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::copyResult(
        const DynInstPtr &inst, const InstResult& mismatch_val, int start_idx)
{
    // We've already popped one dest off the queue,
    // so do the fix-up then start with the next dest reg;
    if (start_idx >= 0) {
        const RegId& idx = inst->destRegIdx(start_idx);
 
        if (idx.classValue() == InvalidRegClass)
            ; // Do nothing.
        else if (idx.classValue() == MiscRegClass)
            thread->setMiscReg(idx.index(), mismatch_val.asRegVal());
        else if (mismatch_val.isBlob())
            thread->setReg(idx, mismatch_val.asBlob());
        else
            thread->setReg(idx, mismatch_val.asRegVal());
    }
    start_idx++;
    InstResult res;
    for (int i = start_idx; i < inst->numDestRegs(); i++) {
        const RegId& idx = inst->destRegIdx(i);
        res = inst->popResult();
 
        if (idx.classValue() == InvalidRegClass)
            ; // Do nothing.
        else if (idx.classValue() == MiscRegClass)
            thread->setMiscReg(idx.index(), 0);
        else if (res.isBlob())
            thread->setReg(idx, res.asBlob());
        else
            thread->setReg(idx, res.asRegVal());
    }
}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::dumpAndExit(const DynInstPtr &inst)
{
    cprintf("Error detected, instruction information:\n");
    cprintf("PC:%s\n[sn:%lli]\n[tid:%i]\n"
            "Completed:%i\n",
            inst->pcState(),
            inst->seqNum,
            inst->threadNumber,
            inst->isCompleted());
    inst->dump();
    CheckerCPU::dumpAndExit();
}
 
template <class DynInstPtr>
void
Checker<DynInstPtr>::dumpInsts()
{
    int num = 0;
 
    InstListIt inst_list_it = --(instList.end());
 
    cprintf("Inst list size: %i\n", instList.size());
 
    while (inst_list_it != instList.end())
    {
        cprintf("Instruction:%i\n",
                num);
 
        cprintf("PC:%s\n[sn:%lli]\n[tid:%i]\n"
                "Completed:%i\n",
                (*inst_list_it)->pcState(),
                (*inst_list_it)->seqNum,
                (*inst_list_it)->threadNumber,
                (*inst_list_it)->isCompleted());
 
        cprintf("\n");
 
        inst_list_it--;
        ++num;
    }
 
}
 
} // namespace gem5
 
#endif//__CPU_CHECKER_CPU_IMPL_HH__