src/cpu/checker/cpu.hh - public/gem5 - Git at Google

 /*
  * Copyright (c) 2011, 2016-2018, 2020-2021 Arm Limited
  * Copyright (c) 2013 Advanced Micro Devices, Inc.
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * property including but not limited to intellectual property relating
  * to a hardware implementation of the functionality of the software
  * licensed hereunder.  You may use the software subject to the license
  * terms below provided that you ensure that this notice is replicated
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Copyright (c) 2006 The Regents of The University of Michigan
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #ifndef __CPU_CHECKER_CPU_HH__
 #define __CPU_CHECKER_CPU_HH__

 #include <list>
 #include <map>
 #include <queue>

 #include "arch/generic/pcstate.hh"
 #include "base/statistics.hh"
 #include "cpu/base.hh"
 #include "cpu/exec_context.hh"
 #include "cpu/inst_res.hh"
 #include "cpu/pc_event.hh"
 #include "cpu/simple_thread.hh"
 #include "cpu/static_inst.hh"
 #include "debug/Checker.hh"
 #include "mem/request.hh"
 #include "params/CheckerCPU.hh"
 #include "sim/eventq.hh"

 namespace gem5
 {

 class ThreadContext;
 class Request;

 /**
  * CheckerCPU class.  Dynamically verifies instructions as they are
  * completed by making sure that the instruction and its results match
  * the independent execution of the benchmark inside the checker.  The
  * checker verifies instructions in order, regardless of the order in
  * which instructions complete.  There are certain results that can
  * not be verified, specifically the result of a store conditional or
  * the values of uncached accesses.  In these cases, and with
  * instructions marked as "IsUnverifiable", the checker assumes that
  * the value from the main CPU's execution is correct and simply
  * copies that value.  It provides a CheckerThreadContext (see
  * checker/thread_context.hh) that provides hooks for updating the
  * Checker's state through any ThreadContext accesses.  This allows the
  * checker to be able to correctly verify instructions, even with
  * external accesses to the ThreadContext that change state.
  */
 class CheckerCPU : public BaseCPU, public ExecContext
 {
   protected:
     /** id attached to all issued requests */
     RequestorID requestorId;

   public:
     void init() override;

     PARAMS(CheckerCPU);
     CheckerCPU(const Params &p);
     virtual ~CheckerCPU();

     void setSystem(System *system);

     void setIcachePort(RequestPort *icache_port);

     void setDcachePort(RequestPort *dcache_port);

     Port &
     getDataPort() override
     {
         // the checker does not have ports on its own so return the
         // data port of the actual CPU core
         assert(dcachePort);
         return *dcachePort;
     }

     Port &
     getInstPort() override
     {
         // the checker does not have ports on its own so return the
         // data port of the actual CPU core
         assert(icachePort);
         return *icachePort;
     }

   protected:

     std::vector<Process*> workload;

     System *systemPtr;

     RequestPort *icachePort;
     RequestPort *dcachePort;

     ThreadContext *tc;

     BaseMMU *mmu;

     // ISAs like ARM can have multiple destination registers to check,
     // keep them all in a std::queue
     std::queue<InstResult> result;

     StaticInstPtr curStaticInst;
     StaticInstPtr curMacroStaticInst;

     // number of simulated instructions
     Counter numInst;
     Counter startNumInst;

     std::queue<int> miscRegIdxs;

   public:

     // Primary thread being run.
     SimpleThread *thread;

     BaseMMU* getMMUPtr() { return mmu; }

     virtual Counter totalInsts() const override { return 0; }

     virtual Counter totalOps() const override { return 0; }

     // number of simulated loads
     Counter numLoad;
     Counter startNumLoad;

     void serialize(CheckpointOut &cp) const override;
     void unserialize(CheckpointIn &cp) override;

     // The register accessor methods provide the index of the
     // instruction's operand (e.g., 0 or 1), not the architectural
     // register index, to simplify the implementation of register
     // renaming.  We find the architectural register index by indexing
     // into the instruction's own operand index table.  Note that a
     // raw pointer to the StaticInst is provided instead of a
     // ref-counted StaticInstPtr to redice overhead.  This is fine as
     // long as these methods don't copy the pointer into any long-term
     // storage (which is pretty hard to imagine they would have reason
     // to do).

     RegVal
     getRegOperand(const StaticInst *si, int idx) override
     {
         return thread->getReg(si->srcRegIdx(idx));
     }

     void
     getRegOperand(const StaticInst *si, int idx, void *val) override
     {
         thread->getReg(si->srcRegIdx(idx), val);
     }

     void *
     getWritableRegOperand(const StaticInst *si, int idx) override
     {
         return thread->getWritableReg(si->destRegIdx(idx));
     }

     void
     setRegOperand(const StaticInst *si, int idx, RegVal val) override
     {
         const RegId& id = si->destRegIdx(idx);
         if (id.is(InvalidRegClass))
             return;
         thread->setReg(id, val);
         result.emplace(val);
     }

     void
     setRegOperand(const StaticInst *si, int idx, const void *val) override
     {
         const RegId& id = si->destRegIdx(idx);
         if (id.is(InvalidRegClass))
             return;
         thread->setReg(id, val);
         //TODO setVecResult, setVecPredResult setVecElemResult?
     }

     bool readPredicate() const override { return thread->readPredicate(); }

     void
     setPredicate(bool val) override
     {
         thread->setPredicate(val);
     }

     bool
     readMemAccPredicate() const override
     {
         return thread->readMemAccPredicate();
     }

     void
     setMemAccPredicate(bool val) override
     {
         thread->setMemAccPredicate(val);
     }

     uint64_t
     getHtmTransactionUid() const override
     {
         panic("not yet supported!");
         return 0;
     };

     uint64_t
     newHtmTransactionUid() const override
     {
         panic("not yet supported!");
         return 0;
     };

     Fault
     initiateMemMgmtCmd(Request::Flags flags) override
     {
         panic("not yet supported!");
         return NoFault;
     }

     bool
     inHtmTransactionalState() const override
     {
         return (getHtmTransactionalDepth() > 0);
     }

     uint64_t
     getHtmTransactionalDepth() const override
     {
         assert(thread->htmTransactionStarts >= thread->htmTransactionStops);
         return (thread->htmTransactionStarts - thread->htmTransactionStops);
     }

     const PCStateBase &
     pcState() const override
     {
         return thread->pcState();
     }
     void
     pcState(const PCStateBase &val) override
     {
         DPRINTF(Checker, "Changing PC to %s, old PC %s.\n",
                          val, thread->pcState());
         thread->pcState(val);
     }
     //////////////////////////////////////////

     RegVal
     readMiscRegNoEffect(int misc_reg) const
     {
         return thread->readMiscRegNoEffect(misc_reg);
     }

     RegVal
     readMiscReg(int misc_reg) override
     {
         return thread->readMiscReg(misc_reg);
     }

     void
     setMiscRegNoEffect(int misc_reg, RegVal val)
     {
         DPRINTF(Checker, "Setting misc reg %d with no effect to check later\n",
                 misc_reg);
         miscRegIdxs.push(misc_reg);
         return thread->setMiscRegNoEffect(misc_reg, val);
     }

     void
     setMiscReg(int misc_reg, RegVal val) override
     {
         DPRINTF(Checker, "Setting misc reg %d with effect to check later\n",
                 misc_reg);
         miscRegIdxs.push(misc_reg);
         return thread->setMiscReg(misc_reg, val);
     }

     RegVal
     readMiscRegOperand(const StaticInst *si, int idx) override
     {
         const RegId& reg = si->srcRegIdx(idx);
         assert(reg.is(MiscRegClass));
         return thread->readMiscReg(reg.index());
     }

     void
     setMiscRegOperand(const StaticInst *si, int idx, RegVal val) override
     {
         const RegId& reg = si->destRegIdx(idx);
         assert(reg.is(MiscRegClass));
         return this->setMiscReg(reg.index(), val);
     }

     /////////////////////////////////////////

     void
     recordPCChange(const PCStateBase &val)
     {
        changedPC = true;
        set(newPCState, val);
     }

     void
     demapPage(Addr vaddr, uint64_t asn) override
     {
         mmu->demapPage(vaddr, asn);
     }

     // monitor/mwait funtions
     void armMonitor(Addr address) override { BaseCPU::armMonitor(0, address); }
     bool mwait(PacketPtr pkt) override { return BaseCPU::mwait(0, pkt); }

     void
     mwaitAtomic(ThreadContext *tc) override
     {
         return BaseCPU::mwaitAtomic(0, tc, thread->mmu);
     }

     AddressMonitor *
     getAddrMonitor() override
     {
         return BaseCPU::getCpuAddrMonitor(0);
     }

     /**
      * Helper function used to generate the request for a single fragment of a
      * memory access.
      *
      * Takes care of setting up the appropriate byte-enable mask for the
      * fragment, given the mask for the entire memory access.
      *
      * @param frag_addr Start address of the fragment.
      * @param size Total size of the memory access in bytes.
      * @param flags Request flags.
      * @param byte_enable Byte-enable mask for the entire memory access.
      * @param[out] frag_size Fragment size.
      * @param[in,out] size_left Size left to be processed in the memory access.
      * @return Pointer to the allocated Request, nullptr if the byte-enable
      * mask is all-false for the fragment.
      */
     RequestPtr genMemFragmentRequest(Addr frag_addr, int size,
                                      Request::Flags flags,
                                      const std::vector<bool>& byte_enable,
                                      int& frag_size, int& size_left) const;

     Fault readMem(Addr addr, uint8_t *data, unsigned size,
                   Request::Flags flags,
                   const std::vector<bool>& byte_enable) override;

     Fault writeMem(uint8_t *data, unsigned size, Addr addr,
                    Request::Flags flags, uint64_t *res,
                    const std::vector<bool>& byte_enable) override;

     Fault
     amoMem(Addr addr, uint8_t* data, unsigned size,
            Request::Flags flags, AtomicOpFunctorPtr amo_op) override
     {
         panic("AMO is not supported yet in CPU checker\n");
     }

     unsigned int
     readStCondFailures() const override
     {
         return thread->readStCondFailures();
     }

     void setStCondFailures(unsigned int sc_failures) override {}
     /////////////////////////////////////////////////////

     void wakeup(ThreadID tid) override { }

     void
     handleError()
     {
         if (exitOnError)
             dumpAndExit();
     }

     bool checkFlags(const RequestPtr &unverified_req, Addr vAddr,
                     Addr pAddr, int flags);

     void dumpAndExit();

     ThreadContext *tcBase() const override { return tc; }
     SimpleThread *threadBase() { return thread; }

     InstResult unverifiedResult;
     RequestPtr unverifiedReq;
     uint8_t *unverifiedMemData;

     bool changedPC;
     bool willChangePC;
     std::unique_ptr<PCStateBase> newPCState;
     bool exitOnError;
     bool updateOnError;
     bool warnOnlyOnLoadError;

     InstSeqNum youngestSN;
 };

 /**
  * Templated Checker class.  This Checker class is templated on the
  * DynInstPtr of the instruction type that will be verified.  Proper
  * template instantiations of the Checker must be placed at the bottom
  * of checker/cpu.cc.
  */
 template <class DynInstPtr>
 class Checker : public CheckerCPU
 {
   public:
     Checker(const Params &p)
         : CheckerCPU(p), updateThisCycle(false), unverifiedInst(NULL)
     { }

     void switchOut();
     void takeOverFrom(BaseCPU *oldCPU);

     void advancePC(const Fault &fault);

     void verify(const DynInstPtr &inst);

     void validateInst(const DynInstPtr &inst);
     void validateExecution(const DynInstPtr &inst);
     void validateState();

     void copyResult(const DynInstPtr &inst, const InstResult& mismatch_val,
                     int start_idx);
     void handlePendingInt();

   private:
     void
     handleError(const DynInstPtr &inst)
     {
         if (exitOnError) {
             dumpAndExit(inst);
         } else if (updateOnError) {
             updateThisCycle = true;
         }
     }

     void dumpAndExit(const DynInstPtr &inst);

     bool updateThisCycle;

     DynInstPtr unverifiedInst;

     std::list<DynInstPtr> instList;
     typedef typename std::list<DynInstPtr>::iterator InstListIt;
     void dumpInsts();
 };

 } // namespace gem5

 #endif // __CPU_CHECKER_CPU_HH__
	/*
	* Copyright (c) 2011, 2016-2018, 2020-2021 Arm Limited
	* Copyright (c) 2013 Advanced Micro Devices, Inc.
	* All rights reserved
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* property including but not limited to intellectual property relating
	* to a hardware implementation of the functionality of the software
	* licensed hereunder. You may use the software subject to the license
	* terms below provided that you ensure that this notice is replicated
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Copyright (c) 2006 The Regents of The University of Michigan
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#ifndef __CPU_CHECKER_CPU_HH__
	#define __CPU_CHECKER_CPU_HH__

	#include <list>
	#include <map>
	#include <queue>

	#include "arch/generic/pcstate.hh"
	#include "base/statistics.hh"
	#include "cpu/base.hh"
	#include "cpu/exec_context.hh"
	#include "cpu/inst_res.hh"
	#include "cpu/pc_event.hh"
	#include "cpu/simple_thread.hh"
	#include "cpu/static_inst.hh"
	#include "debug/Checker.hh"
	#include "mem/request.hh"
	#include "params/CheckerCPU.hh"
	#include "sim/eventq.hh"

	namespace gem5
	{

	class ThreadContext;
	class Request;

	/**
	* CheckerCPU class. Dynamically verifies instructions as they are
	* completed by making sure that the instruction and its results match
	* the independent execution of the benchmark inside the checker. The
	* checker verifies instructions in order, regardless of the order in
	* which instructions complete. There are certain results that can
	* not be verified, specifically the result of a store conditional or
	* the values of uncached accesses. In these cases, and with
	* instructions marked as "IsUnverifiable", the checker assumes that
	* the value from the main CPU's execution is correct and simply
	* copies that value. It provides a CheckerThreadContext (see
	* checker/thread_context.hh) that provides hooks for updating the
	* Checker's state through any ThreadContext accesses. This allows the
	* checker to be able to correctly verify instructions, even with
	* external accesses to the ThreadContext that change state.
	*/
	class CheckerCPU : public BaseCPU, public ExecContext
	{
	protected:
	/** id attached to all issued requests */
	RequestorID requestorId;

	public:
	void init() override;

	PARAMS(CheckerCPU);
	CheckerCPU(const Params &p);
	virtual ~CheckerCPU();

	void setSystem(System *system);

	void setIcachePort(RequestPort *icache_port);

	void setDcachePort(RequestPort *dcache_port);

	Port &
	getDataPort() override
	{
	// the checker does not have ports on its own so return the
	// data port of the actual CPU core
	assert(dcachePort);
	return *dcachePort;
	}

	Port &
	getInstPort() override
	{
	// the checker does not have ports on its own so return the
	// data port of the actual CPU core
	assert(icachePort);
	return *icachePort;
	}

	protected:

	std::vector<Process*> workload;

	System *systemPtr;

	RequestPort *icachePort;
	RequestPort *dcachePort;

	ThreadContext *tc;

	BaseMMU *mmu;

	// ISAs like ARM can have multiple destination registers to check,
	// keep them all in a std::queue
	std::queue<InstResult> result;

	StaticInstPtr curStaticInst;
	StaticInstPtr curMacroStaticInst;

	// number of simulated instructions
	Counter numInst;
	Counter startNumInst;

	std::queue<int> miscRegIdxs;

	public:

	// Primary thread being run.
	SimpleThread *thread;

	BaseMMU* getMMUPtr() { return mmu; }

	virtual Counter totalInsts() const override { return 0; }

	virtual Counter totalOps() const override { return 0; }

	// number of simulated loads
	Counter numLoad;
	Counter startNumLoad;

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	// The register accessor methods provide the index of the
	// instruction's operand (e.g., 0 or 1), not the architectural
	// register index, to simplify the implementation of register
	// renaming. We find the architectural register index by indexing
	// into the instruction's own operand index table. Note that a
	// raw pointer to the StaticInst is provided instead of a
	// ref-counted StaticInstPtr to redice overhead. This is fine as
	// long as these methods don't copy the pointer into any long-term
	// storage (which is pretty hard to imagine they would have reason
	// to do).

	RegVal
	getRegOperand(const StaticInst *si, int idx) override
	{
	return thread->getReg(si->srcRegIdx(idx));
	}

	void
	getRegOperand(const StaticInst si, int idx, void val) override
	{
	thread->getReg(si->srcRegIdx(idx), val);
	}

	void *
	getWritableRegOperand(const StaticInst *si, int idx) override
	{
	return thread->getWritableReg(si->destRegIdx(idx));
	}

	void
	setRegOperand(const StaticInst *si, int idx, RegVal val) override
	{
	const RegId& id = si->destRegIdx(idx);
	if (id.is(InvalidRegClass))
	return;
	thread->setReg(id, val);
	result.emplace(val);
	}

	void
	setRegOperand(const StaticInst si, int idx, const void val) override
	{
	const RegId& id = si->destRegIdx(idx);
	if (id.is(InvalidRegClass))
	return;
	thread->setReg(id, val);
	//TODO setVecResult, setVecPredResult setVecElemResult?
	}

	bool readPredicate() const override { return thread->readPredicate(); }

	void
	setPredicate(bool val) override
	{
	thread->setPredicate(val);
	}

	bool
	readMemAccPredicate() const override
	{
	return thread->readMemAccPredicate();
	}

	void
	setMemAccPredicate(bool val) override
	{
	thread->setMemAccPredicate(val);
	}

	uint64_t
	getHtmTransactionUid() const override
	{
	panic("not yet supported!");
	return 0;
	};

	uint64_t
	newHtmTransactionUid() const override
	{
	panic("not yet supported!");
	return 0;
	};

	Fault
	initiateMemMgmtCmd(Request::Flags flags) override
	{
	panic("not yet supported!");
	return NoFault;
	}

	bool
	inHtmTransactionalState() const override
	{
	return (getHtmTransactionalDepth() > 0);
	}

	uint64_t
	getHtmTransactionalDepth() const override
	{
	assert(thread->htmTransactionStarts >= thread->htmTransactionStops);
	return (thread->htmTransactionStarts - thread->htmTransactionStops);
	}

	const PCStateBase &
	pcState() const override
	{
	return thread->pcState();
	}
	void
	pcState(const PCStateBase &val) override
	{
	DPRINTF(Checker, "Changing PC to %s, old PC %s.\n",
	val, thread->pcState());
	thread->pcState(val);
	}
	//////////////////////////////////////////

	RegVal
	readMiscRegNoEffect(int misc_reg) const
	{
	return thread->readMiscRegNoEffect(misc_reg);
	}

	RegVal
	readMiscReg(int misc_reg) override
	{
	return thread->readMiscReg(misc_reg);
	}

	void
	setMiscRegNoEffect(int misc_reg, RegVal val)
	{
	DPRINTF(Checker, "Setting misc reg %d with no effect to check later\n",
	misc_reg);
	miscRegIdxs.push(misc_reg);
	return thread->setMiscRegNoEffect(misc_reg, val);
	}

	void
	setMiscReg(int misc_reg, RegVal val) override
	{
	DPRINTF(Checker, "Setting misc reg %d with effect to check later\n",
	misc_reg);
	miscRegIdxs.push(misc_reg);
	return thread->setMiscReg(misc_reg, val);
	}

	RegVal
	readMiscRegOperand(const StaticInst *si, int idx) override
	{
	const RegId& reg = si->srcRegIdx(idx);
	assert(reg.is(MiscRegClass));
	return thread->readMiscReg(reg.index());
	}

	void
	setMiscRegOperand(const StaticInst *si, int idx, RegVal val) override
	{
	const RegId& reg = si->destRegIdx(idx);
	assert(reg.is(MiscRegClass));
	return this->setMiscReg(reg.index(), val);
	}

	/////////////////////////////////////////

	void
	recordPCChange(const PCStateBase &val)
	{
	changedPC = true;
	set(newPCState, val);
	}

	void
	demapPage(Addr vaddr, uint64_t asn) override
	{
	mmu->demapPage(vaddr, asn);
	}

	// monitor/mwait funtions
	void armMonitor(Addr address) override { BaseCPU::armMonitor(0, address); }
	bool mwait(PacketPtr pkt) override { return BaseCPU::mwait(0, pkt); }

	void
	mwaitAtomic(ThreadContext *tc) override
	{
	return BaseCPU::mwaitAtomic(0, tc, thread->mmu);
	}

	AddressMonitor *
	getAddrMonitor() override
	{
	return BaseCPU::getCpuAddrMonitor(0);
	}

	/**
	* Helper function used to generate the request for a single fragment of a
	* memory access.
	*
	* Takes care of setting up the appropriate byte-enable mask for the
	* fragment, given the mask for the entire memory access.
	*
	* @param frag_addr Start address of the fragment.
	* @param size Total size of the memory access in bytes.
	* @param flags Request flags.
	* @param byte_enable Byte-enable mask for the entire memory access.
	* @param[out] frag_size Fragment size.
	* @param[in,out] size_left Size left to be processed in the memory access.
	* @return Pointer to the allocated Request, nullptr if the byte-enable
	* mask is all-false for the fragment.
	*/
	RequestPtr genMemFragmentRequest(Addr frag_addr, int size,
	Request::Flags flags,
	const std::vector<bool>& byte_enable,
	int& frag_size, int& size_left) const;

	Fault readMem(Addr addr, uint8_t *data, unsigned size,
	Request::Flags flags,
	const std::vector<bool>& byte_enable) override;

	Fault writeMem(uint8_t *data, unsigned size, Addr addr,
	Request::Flags flags, uint64_t *res,
	const std::vector<bool>& byte_enable) override;

	Fault
	amoMem(Addr addr, uint8_t* data, unsigned size,
	Request::Flags flags, AtomicOpFunctorPtr amo_op) override
	{
	panic("AMO is not supported yet in CPU checker\n");
	}

	unsigned int
	readStCondFailures() const override
	{
	return thread->readStCondFailures();
	}

	void setStCondFailures(unsigned int sc_failures) override {}
	/////////////////////////////////////////////////////

	void wakeup(ThreadID tid) override { }

	void
	handleError()
	{
	if (exitOnError)
	dumpAndExit();
	}

	bool checkFlags(const RequestPtr &unverified_req, Addr vAddr,
	Addr pAddr, int flags);

	void dumpAndExit();

	ThreadContext *tcBase() const override { return tc; }
	SimpleThread *threadBase() { return thread; }

	InstResult unverifiedResult;
	RequestPtr unverifiedReq;
	uint8_t *unverifiedMemData;

	bool changedPC;
	bool willChangePC;
	std::unique_ptr<PCStateBase> newPCState;
	bool exitOnError;
	bool updateOnError;
	bool warnOnlyOnLoadError;

	InstSeqNum youngestSN;
	};

	/**
	* Templated Checker class. This Checker class is templated on the
	* DynInstPtr of the instruction type that will be verified. Proper
	* template instantiations of the Checker must be placed at the bottom
	* of checker/cpu.cc.
	*/
	template <class DynInstPtr>
	class Checker : public CheckerCPU
	{
	public:
	Checker(const Params &p)
	: CheckerCPU(p), updateThisCycle(false), unverifiedInst(NULL)
	{ }

	void switchOut();
	void takeOverFrom(BaseCPU *oldCPU);

	void advancePC(const Fault &fault);

	void verify(const DynInstPtr &inst);

	void validateInst(const DynInstPtr &inst);
	void validateExecution(const DynInstPtr &inst);
	void validateState();

	void copyResult(const DynInstPtr &inst, const InstResult& mismatch_val,
	int start_idx);
	void handlePendingInt();

	private:
	void
	handleError(const DynInstPtr &inst)
	{
	if (exitOnError) {
	dumpAndExit(inst);
	} else if (updateOnError) {
	updateThisCycle = true;
	}
	}

	void dumpAndExit(const DynInstPtr &inst);

	bool updateThisCycle;

	DynInstPtr unverifiedInst;

	std::list<DynInstPtr> instList;
	typedef typename std::list<DynInstPtr>::iterator InstListIt;
	void dumpInsts();
	};

	} // namespace gem5

	#endif // __CPU_CHECKER_CPU_HH__