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/*
* 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
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*
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* 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
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#ifndef __ARCH_RISCV_TABLE_WALKER_HH__
#define __ARCH_RISCV_TABLE_WALKER_HH__
#include <vector>
#include "arch/generic/mmu.hh"
#include "arch/riscv/pagetable.hh"
#include "arch/riscv/pma_checker.hh"
#include "arch/riscv/pmp.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"
namespace gem5
{
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)
{}
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;
BaseMMU::Translation * translation;
BaseMMU::Mode mode;
SATP satp;
STATUS status;
PrivilegeMode pmode;
bool functional;
bool timing;
bool retrying;
bool started;
bool squashed;
public:
WalkerState(Walker * _walker, BaseMMU::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, BaseMMU::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, BaseMMU::Translation *translation,
const RequestPtr &req, BaseMMU::Mode mode);
Fault startFunctional(ThreadContext * _tc, Addr &addr,
unsigned &logBytes, BaseMMU::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;
PMAChecker * pma;
PMP * pmp;
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;
}
using Params = RiscvPagetableWalkerParams;
Walker(const Params &params) :
ClockedObject(params), port(name() + ".port", this),
funcState(this, NULL, NULL, true), tlb(NULL), sys(params.system),
pma(params.pma_checker),
pmp(params.pmp),
requestorId(sys->getRequestorId(this)),
numSquashable(params.num_squash_per_cycle),
startWalkWrapperEvent([this]{ startWalkWrapper(); }, name())
{
}
};
} // namespace RiscvISA
} // namespace gem5
#endif // __ARCH_RISCV_PAGE_TABLE_WALKER_HH__