xref: /gem5/src/arch/mips/tlb.hh

/*
 * Copyright (c) 2007 MIPS Technologies, Inc.
 * 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.
 *
 * Authors: Jaidev Patwardhan
 */

#ifndef __ARCH_MIPS_TLB_HH__
#define __ARCH_MIPS_TLB_HH__

#include <map>

#include "arch/mips/isa_traits.hh"
#include "arch/mips/utility.hh"
#include "arch/mips/vtophys.hh"
#include "arch/mips/pagetable.hh"
#include "base/statistics.hh"
#include "mem/request.hh"
#include "params/MipsDTB.hh"
#include "params/MipsITB.hh"
#include "sim/faults.hh"
#include "sim/tlb.hh"
#include "sim/sim_object.hh"

class ThreadContext;

/* MIPS does not distinguish between a DTLB and an ITLB -> unified TLB
   However, to maintain compatibility with other architectures, we'll
   simply create an ITLB and DTLB that will point to the real TLB */
namespace MipsISA {

// WARN: This particular TLB entry is not necessarily conformed to MIPS ISA
// We just need this to make compiler happy. Use "PTE" type for real entry.
struct TlbEntry
{
    Addr _pageStart;
    TlbEntry() {}
    TlbEntry(Addr asn, Addr vaddr, Addr paddr) : _pageStart(paddr) {}

    Addr pageStart()
    {
        return _pageStart;
    }

    void serialize(std::ostream &os)
    {
        SERIALIZE_SCALAR(_pageStart);
    }

    void unserialize(Checkpoint *cp, const std::string &section)
    {
        UNSERIALIZE_SCALAR(_pageStart);
    }

};

class TLB : public SimObject
{
  protected:
    typedef std::multimap<Addr, int> PageTable;
    PageTable lookupTable;	// Quick lookup into page table

    MipsISA::PTE *table;	// the Page Table
    int size;			// TLB Size
    int nlu;			// not last used entry (for replacement)

    void nextnlu() { if (++nlu >= size) nlu = 0; }
    MipsISA::PTE *lookup(Addr vpn, uint8_t asn) const;

    mutable Stats::Scalar<> read_hits;
    mutable Stats::Scalar<> read_misses;
    mutable Stats::Scalar<> read_acv;
    mutable Stats::Scalar<> read_accesses;
    mutable Stats::Scalar<> write_hits;
    mutable Stats::Scalar<> write_misses;
    mutable Stats::Scalar<> write_acv;
    mutable Stats::Scalar<> write_accesses;
    Stats::Formula hits;
    Stats::Formula misses;
    Stats::Formula invalids;
    Stats::Formula accesses;

  public:
    typedef MipsTLBParams Params;
    TLB(const Params *p);

    int probeEntry(Addr vpn,uint8_t) const;
    MipsISA::PTE *getEntry(unsigned) const;
    virtual ~TLB();
    int smallPages;
    int getsize() const { return size; }

    MipsISA::PTE &index(bool advance = true);
    void insert(Addr vaddr, MipsISA::PTE &pte);
    void insertAt(MipsISA::PTE &pte, unsigned Index, int _smallPages);
    void flushAll();

    // static helper functions... really
    static bool validVirtualAddress(Addr vaddr);

    static Fault checkCacheability(RequestPtr &req);

    // Checkpointing
    void serialize(std::ostream &os);
    void unserialize(Checkpoint *cp, const std::string &section);

    void regStats();
};

class ITB : public TLB {
  public:
    typedef MipsTLBParams Params;
    ITB(const Params *p);

    Fault translate(RequestPtr &req, ThreadContext *tc);
};

class DTB : public TLB {
  public:
    typedef MipsTLBParams Params;
    DTB(const Params *p);

    Fault translate(RequestPtr &req, ThreadContext *tc, bool write = false);
};

class UTB : public ITB, public DTB {
  public:
    typedef MipsTLBParams Params;
    UTB(const Params *p);

};

}



#endif // __MIPS_MEMORY_HH__