cache_blk.hh

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#ifndef __MEM_CACHE_CACHE_BLK_HH__
#define __MEM_CACHE_CACHE_BLK_HH__
 
#include <cassert>
#include <cstdint>
#include <iosfwd>
#include <list>
#include <string>
 
#include "base/printable.hh"
#include "base/types.hh"
#include "mem/cache/tags/tagged_entry.hh"
#include "mem/packet.hh"
#include "mem/request.hh"
#include "sim/cur_tick.hh"
 
namespace gem5
{
 
class CacheBlk : public TaggedEntry
{
  public:
    enum CoherenceBits : unsigned
    {
        WritableBit =       0x02,
        ReadableBit =       0x04,
        DirtyBit =          0x08,
 
        AllBits  =          0x0E,
    };
 
    uint8_t *data = nullptr;
 
    Tick whenReady = 0;
 
  protected:
    class Lock
    {
      public:
        ContextID contextId;     // locking context
        Addr lowAddr;      // low address of lock range
        Addr highAddr;     // high address of lock range
 
        // check for matching execution context, and an address that
        // is within the lock
        bool matches(const RequestPtr &req) const
        {
            Addr req_low = req->getPaddr();
            Addr req_high = req_low + req->getSize() -1;
            return (contextId == req->contextId()) &&
                   (req_low >= lowAddr) && (req_high <= highAddr);
        }
 
        // check if a request is intersecting and thus invalidating the lock
        bool intersects(const RequestPtr &req) const
        {
            Addr req_low = req->getPaddr();
            Addr req_high = req_low + req->getSize() - 1;
 
            return (req_low <= highAddr) && (req_high >= lowAddr);
        }
 
        Lock(const RequestPtr &req)
            : contextId(req->contextId()),
              lowAddr(req->getPaddr()),
              highAddr(lowAddr + req->getSize() - 1)
        {
        }
    };
 
    std::list<Lock> lockList;
 
  public:
    CacheBlk()
    {
        invalidate();
    }
 
    CacheBlk(const CacheBlk&) = delete;
    CacheBlk& operator=(const CacheBlk&) = delete;
    CacheBlk(const CacheBlk&&) = delete;
    virtual CacheBlk&
    operator=(CacheBlk&& other)
    {
        // Copying an entry into a valid one would imply in skipping all
        // replacement steps, so it cannot be allowed
        assert(!isValid());
        assert(other.isValid());
 
        insert(other.getTag(), other.isSecure());
 
        if (other.wasPrefetched()) {
            setPrefetched();
        }
        setCoherenceBits(other.coherence);
        setTaskId(other.getTaskId());
        setWhenReady(curTick());
        setRefCount(other.getRefCount());
        setSrcRequestorId(other.getSrcRequestorId());
        std::swap(lockList, other.lockList);
 
        other.invalidate();
 
        return *this;
    }
    virtual ~CacheBlk() {};
 
    virtual void invalidate() override
    {
        TaggedEntry::invalidate();
 
        clearPrefetched();
        clearCoherenceBits(AllBits);
 
        setTaskId(context_switch_task_id::Unknown);
        setWhenReady(MaxTick);
        setRefCount(0);
        setSrcRequestorId(Request::invldRequestorId);
        lockList.clear();
    }
 
    void
    setCoherenceBits(unsigned bits)
    {
        assert(isValid());
        coherence |= bits;
    }
 
    void clearCoherenceBits(unsigned bits) { coherence &= ~bits; }
 
    bool
    isSet(unsigned bits) const
    {
        return isValid() && (coherence & bits);
    }
 
    bool wasPrefetched() const { return _prefetched; }
 
    void clearPrefetched() { _prefetched = false; }
 
    void setPrefetched() { _prefetched = true; }
 
    Tick getWhenReady() const
    {
        assert(whenReady != MaxTick);
        return whenReady;
    }
 
    void setWhenReady(const Tick tick)
    {
        assert(tick >= _tickInserted);
        whenReady = tick;
    }
 
    uint32_t getTaskId() const { return _taskId; }
 
    uint32_t getSrcRequestorId() const { return _srcRequestorId; }
 
    unsigned getRefCount() const { return _refCount; }
 
    void increaseRefCount() { _refCount++; }
 
    Tick
    getAge() const
    {
        assert(_tickInserted <= curTick());
        return curTick() - _tickInserted;
    }
 
    void insert(const Addr tag, const bool is_secure,
        const int src_requestor_ID, const uint32_t task_ID);
    using TaggedEntry::insert;
 
    void trackLoadLocked(PacketPtr pkt)
    {
        assert(pkt->isLLSC());
        auto l = lockList.begin();
        while (l != lockList.end()) {
            if (l->intersects(pkt->req))
                l = lockList.erase(l);
            else
                ++l;
        }
 
        lockList.emplace_front(pkt->req);
    }
 
    void clearLoadLocks(const RequestPtr &req)
    {
        auto l = lockList.begin();
        while (l != lockList.end()) {
            if (l->intersects(req) && l->contextId != req->contextId()) {
                l = lockList.erase(l);
            } else {
                ++l;
            }
        }
    }
 
    std::string
    print() const override
    {
        unsigned state =
            isSet(WritableBit) << 2 | isSet(DirtyBit) << 1 | isValid();
        char s = '?';
        switch (state) {
          case 0b111: s = 'M'; break;
          case 0b011: s = 'O'; break;
          case 0b101: s = 'E'; break;
          case 0b001: s = 'S'; break;
          case 0b000: s = 'I'; break;
          default:    s = 'T'; break; // @TODO add other types
        }
        return csprintf("state: %x (%c) writable: %d readable: %d "
            "dirty: %d prefetched: %d | %s", coherence, s,
            isSet(WritableBit), isSet(ReadableBit), isSet(DirtyBit),
            wasPrefetched(), TaggedEntry::print());
    }
 
    bool checkWrite(PacketPtr pkt)
    {
        assert(pkt->isWrite());
 
        // common case
        if (!pkt->isLLSC() && lockList.empty())
            return true;
 
        const RequestPtr &req = pkt->req;
 
        if (pkt->isLLSC()) {
            // it's a store conditional... have to check for matching
            // load locked.
            bool success = false;
 
            auto l = lockList.begin();
            while (!success && l != lockList.end()) {
                if (l->matches(pkt->req)) {
                    // it's a store conditional, and as far as the
                    // memory system can tell, the requesting
                    // context's lock is still valid.
                    success = true;
                    lockList.erase(l);
                } else {
                    ++l;
                }
            }
 
            req->setExtraData(success ? 1 : 0);
            // clear any intersected locks from other contexts (our LL
            // should already have cleared them)
            clearLoadLocks(req);
            return success;
        } else {
            // a normal write, if there is any lock not from this
            // context we clear the list, thus for a private cache we
            // never clear locks on normal writes
            clearLoadLocks(req);
            return true;
        }
    }
 
  protected:
    unsigned coherence;
 
    // The following setters have been marked as protected because their
    // respective variables should only be modified at 2 moments:
    // invalidation and insertion. Because of that, they shall only be
    // called by the functions that perform those actions.
 
    void setTaskId(const uint32_t task_id) { _taskId = task_id; }
 
    void setSrcRequestorId(const uint32_t id) { _srcRequestorId = id; }
 
    void setRefCount(const unsigned count) { _refCount = count; }
 
    void setTickInserted() { _tickInserted = curTick(); }
 
  private:
    uint32_t _taskId = 0;
 
    int _srcRequestorId = 0;
 
    unsigned _refCount = 0;
 
    Tick _tickInserted = 0;
 
    bool _prefetched = 0;
};
 
class TempCacheBlk final : public CacheBlk
{
  private:
    Addr _addr;
 
  public:
    TempCacheBlk(unsigned size) : CacheBlk()
    {
        data = new uint8_t[size];
    }
    TempCacheBlk(const TempCacheBlk&) = delete;
    TempCacheBlk& operator=(const TempCacheBlk&) = delete;
    ~TempCacheBlk() { delete [] data; };
 
    void invalidate() override {
        CacheBlk::invalidate();
 
        _addr = MaxAddr;
    }
 
    void
    insert(const Addr addr, const bool is_secure) override
    {
        CacheBlk::insert(addr, is_secure);
        _addr = addr;
    }
 
    Addr getAddr() const
    {
        return _addr;
    }
};
 
class CacheBlkPrintWrapper : public Printable
{
    CacheBlk *blk;
  public:
    CacheBlkPrintWrapper(CacheBlk *_blk) : blk(_blk) {}
    virtual ~CacheBlkPrintWrapper() {}
    void print(std::ostream &o, int verbosity = 0,
               const std::string &prefix = "") const;
};
 
} // namespace gem5
 
#endif //__MEM_CACHE_CACHE_BLK_HH__