text: /*
   * Copyright (c) 2007 The Hewlett-Packard Development Company
   * Copyright (c) 2020 Barkhausen Institut
   * 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.
   *
   * 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 __ARCH_RISCV_TABLE_WALKER_HH__
  #define __ARCH_RISCV_TABLE_WALKER_HH__
  
  #include <vector>
  
  #include "arch/riscv/pagetable.hh"
  #include "arch/riscv/tlb.hh"
  #include "base/types.hh"
  #include "mem/packet.hh"
  #include "params/RiscvPagetableWalker.hh"
  #include "sim/clocked_object.hh"
  #include "sim/faults.hh"
  #include "sim/system.hh"
  
  class ThreadContext;
  
  namespace RiscvISA
  {
      class Walker : public ClockedObject
      {
        protected:
          // Port for accessing memory
          class WalkerPort : public RequestPort
          {
            public:
              WalkerPort(const std::string &_name, Walker * _walker) :
                    RequestPort(_name, _walker), walker(_walker)
              {}
  
            protected:
              Walker *walker;
  
              bool recvTimingResp(PacketPtr pkt);
              void recvReqRetry();
          };
  
          friend class WalkerPort;
          WalkerPort port;
  
          // State to track each walk of the page table
          class WalkerState
          {
            friend class Walker;
            private:
              enum State {
                  Ready,
                  Waiting,
                  Translate,
              };
  
            protected:
              Walker *walker;
              ThreadContext *tc;
              RequestPtr req;
              State state;
              State nextState;
              int level;
              unsigned inflight;
              TlbEntry entry;
              PacketPtr read;
              std::vector<PacketPtr> writes;
              Fault timingFault;
              TLB::Translation * translation;
              BaseTLB::Mode mode;
              SATP satp;
              STATUS status;
              PrivilegeMode pmode;
              bool functional;
              bool timing;
              bool retrying;
              bool started;
              bool squashed;
            public:
              WalkerState(Walker * _walker, BaseTLB::Translation *_translation,
                          const RequestPtr &_req, bool _isFunctional = false) :
                  walker(_walker), req(_req), state(Ready),
                  nextState(Ready), level(0), inflight(0),
                  translation(_translation),
                  functional(_isFunctional), timing(false),
                  retrying(false), started(false), squashed(false)
              {
              }
              void initState(ThreadContext * _tc, BaseTLB::Mode _mode,
                             bool _isTiming = false);
              Fault startWalk();
              Fault startFunctional(Addr &addr, unsigned &logBytes);
              bool recvPacket(PacketPtr pkt);
              unsigned numInflight() const;
              bool isRetrying();
              bool wasStarted();
              bool isTiming();
              void retry();
              void squash();
              std::string name() const {return walker->name();}
  
            private:
              void setupWalk(Addr vaddr);
              Fault stepWalk(PacketPtr &write);
              void sendPackets();
              void endWalk();
              Fault pageFault(bool present);
          };
  
          friend class WalkerState;
          // State for timing and atomic accesses (need multiple per walker in
          // the case of multiple outstanding requests in timing mode)
          std::list<WalkerState *> currStates;
          // State for functional accesses (only need one of these per walker)
          WalkerState funcState;
  
          struct WalkerSenderState : public Packet::SenderState
          {
              WalkerState * senderWalk;
              WalkerSenderState(WalkerState * _senderWalk) :
                  senderWalk(_senderWalk) {}
          };
  
        public:
          // Kick off the state machine.
          Fault start(ThreadContext * _tc, BaseTLB::Translation *translation,
                  const RequestPtr &req, BaseTLB::Mode mode);
          Fault startFunctional(ThreadContext * _tc, Addr &addr,
                  unsigned &logBytes, BaseTLB::Mode mode);
          Port &getPort(const std::string &if_name,
                        PortID idx=InvalidPortID) override;
  
        protected:
          // The TLB we're supposed to load.
          TLB * tlb;
          System * sys;
          RequestorID requestorId;
  
          // The number of outstanding walks that can be squashed per cycle.
          unsigned numSquashable;
  
          // Wrapper for checking for squashes before starting a translation.
          void startWalkWrapper();
  
          /**
           * Event used to call startWalkWrapper.
           **/
          EventFunctionWrapper startWalkWrapperEvent;
  
          // Functions for dealing with packets.
          bool recvTimingResp(PacketPtr pkt);
          void recvReqRetry();
          bool sendTiming(WalkerState * sendingState, PacketPtr pkt);
  
        public:
  
          void setTLB(TLB * _tlb)
          {
              tlb = _tlb;
          }
  
          typedef RiscvPagetableWalkerParams Params;
  
          const Params &
          params() const
          {
              return static_cast<const Params &>(_params);
          }
  
          Walker(const Params &params) :
              ClockedObject(params), port(name() + ".port", this),
              funcState(this, NULL, NULL, true), tlb(NULL), sys(params.system),
              requestorId(sys->getRequestorId(this)),
              numSquashable(params.num_squash_per_cycle),
              startWalkWrapperEvent([this]{ startWalkWrapper(); }, name())
          {
          }
      };
  }
  
  #endif // __ARCH_RISCV_PAGE_TABLE_WALKER_HH__
  