This patch enables all 4 CPU models (AtomicSimpleCPU, TimingSimpleCPU, MinorCPU and DerivO3CPU) to issue atomic memory (AMO) requests to memory system. Atomic memory instruction is treated as a special store instruction in all CPU models. In simple CPUs, an AMO request with an associated AtomicOpFunctor is simply sent to L1 dcache. In MinorCPU, an AMO request bypasses store buffer and waits for any conflicting store request(s) currently in the store buffer to retire before the AMO request is sent to the cache. AMO requests are not buffered in the store buffer, so their effects appear immediately in the cache. In DerivO3CPU, an AMO request is inserted in the store buffer so that it is delivered to the cache only after all previous stores are issued to the cache. Data forwarding between between an outstanding AMO in the store buffer and a subsequent load is not allowed since the AMO request does not hold valid data until it's executed in the cache. This implementation assumes that a target ISA implementation must insert enough memory fences as micro-ops around an atomic instruction to enforce a correct order of memory instructions with respect to its memory consistency model. Without extra memory fences, this implementation can allow AMOs and other memory instructions that do not conflict (i.e., not target the same address) to reorder. This implementation also assumes that atomic instructions execute within a cache line boundary since the cache for now is not able to execute an operation on two different cache lines in one single step. Therefore, ISAs like x86 that require multi-cache-line atomic instructions need to either use a pair of locking load and unlocking store or change the cache implementation to guarantee the atomicity of an atomic instruction. Change-Id: Ib8a7c81868ac05b98d73afc7d16eb88486f8cf9a Reviewed-on: https://gem5-review.googlesource.com/c/8188 Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Maintainer: Jason Lowe-Power <jason@lowepower.com>
177 lines
5.5 KiB
C++
177 lines
5.5 KiB
C++
/*
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* Copyright (c) 2011-2012,2015 ARM Limited
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* Copyright (c) 2013 Advanced Micro Devices, Inc.
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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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* Copyright (c) 2002-2005 The Regents of The University of Michigan
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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: Steve Reinhardt
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* Dave Greene
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* Nathan Binkert
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*/
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#ifndef __CPU_SIMPLE_BASE_HH__
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#define __CPU_SIMPLE_BASE_HH__
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#include "base/statistics.hh"
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#include "config/the_isa.hh"
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#include "cpu/base.hh"
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#include "cpu/checker/cpu.hh"
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#include "cpu/exec_context.hh"
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#include "cpu/pc_event.hh"
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#include "cpu/simple_thread.hh"
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#include "cpu/static_inst.hh"
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#include "mem/packet.hh"
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#include "mem/port.hh"
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#include "mem/request.hh"
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#include "sim/eventq.hh"
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#include "sim/full_system.hh"
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#include "sim/system.hh"
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// forward declarations
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class Checkpoint;
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class Process;
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class Processor;
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class ThreadContext;
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namespace TheISA
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{
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class DTB;
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class ITB;
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}
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namespace Trace {
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class InstRecord;
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}
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struct BaseSimpleCPUParams;
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class BPredUnit;
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class SimpleExecContext;
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class BaseSimpleCPU : public BaseCPU
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{
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protected:
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ThreadID curThread;
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BPredUnit *branchPred;
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void checkPcEventQueue();
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void swapActiveThread();
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public:
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BaseSimpleCPU(BaseSimpleCPUParams *params);
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virtual ~BaseSimpleCPU();
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void wakeup(ThreadID tid) override;
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void init() override;
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public:
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Trace::InstRecord *traceData;
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CheckerCPU *checker;
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std::vector<SimpleExecContext*> threadInfo;
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std::list<ThreadID> activeThreads;
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/** Current instruction */
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TheISA::MachInst inst;
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StaticInstPtr curStaticInst;
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StaticInstPtr curMacroStaticInst;
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protected:
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enum Status {
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Idle,
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Running,
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Faulting,
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ITBWaitResponse,
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IcacheRetry,
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IcacheWaitResponse,
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IcacheWaitSwitch,
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DTBWaitResponse,
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DcacheRetry,
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DcacheWaitResponse,
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DcacheWaitSwitch,
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};
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Status _status;
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public:
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Addr dbg_vtophys(Addr addr);
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void checkForInterrupts();
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void setupFetchRequest(const RequestPtr &req);
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void preExecute();
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void postExecute();
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void advancePC(const Fault &fault);
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void haltContext(ThreadID thread_num) override;
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// statistics
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void regStats() override;
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void resetStats() override;
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void startup() override;
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virtual Fault readMem(Addr addr, uint8_t* data, unsigned size,
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Request::Flags flags)
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{ panic("readMem() is not implemented\n"); }
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virtual Fault initiateMemRead(Addr addr, unsigned size,
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Request::Flags flags)
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{ panic("initiateMemRead() is not implemented\n"); }
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virtual Fault writeMem(uint8_t* data, unsigned size, Addr addr,
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Request::Flags flags, uint64_t* res)
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{ panic("writeMem() is not implemented\n"); }
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virtual Fault amoMem(Addr addr, uint8_t* data, unsigned size,
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Request::Flags flags,
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AtomicOpFunctor *amo_op)
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{ panic("amoMem() is not implemented\n"); }
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virtual Fault initiateMemAMO(Addr addr, unsigned size,
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Request::Flags flags,
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AtomicOpFunctor *amo_op)
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{ panic("initiateMemAMO() is not implemented\n"); }
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void countInst();
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Counter totalInsts() const override;
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Counter totalOps() const override;
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void serializeThread(CheckpointOut &cp, ThreadID tid) const override;
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void unserializeThread(CheckpointIn &cp, ThreadID tid) override;
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};
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#endif // __CPU_SIMPLE_BASE_HH__
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