cache.hh revision 9814:7ad2b0186a32 
1/*
2 * Copyright (c) 2012-2013 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Erik Hallnor
41 *          Dave Greene
42 *          Steve Reinhardt
43 *          Ron Dreslinski
44 *          Andreas Hansson
45 */
46
47/**
48 * @file
49 * Describes a cache based on template policies.
50 */
51
52#ifndef __CACHE_HH__
53#define __CACHE_HH__
54
55#include "base/misc.hh" // fatal, panic, and warn
56#include "mem/cache/base.hh"
57#include "mem/cache/blk.hh"
58#include "mem/cache/mshr.hh"
59#include "sim/eventq.hh"
60
61//Forward decleration
62class BasePrefetcher;
63
64/**
65 * A template-policy based cache. The behavior of the cache can be altered by
66 * supplying different template policies. TagStore handles all tag and data
67 * storage @sa TagStore, \ref gem5MemorySystem "gem5 Memory System"
68 */
69template <class TagStore>
70class Cache : public BaseCache
71{
72  public:
73    /** Define the type of cache block to use. */
74    typedef typename TagStore::BlkType BlkType;
75    /** A typedef for a list of BlkType pointers. */
76    typedef typename TagStore::BlkList BlkList;
77
78  protected:
79    typedef CacheBlkVisitorWrapper<Cache<TagStore>, BlkType> WrappedBlkVisitor;
80
81    /**
82     * The CPU-side port extends the base cache slave port with access
83     * functions for functional, atomic and timing requests.
84     */
85    class CpuSidePort : public CacheSlavePort
86    {
87      private:
88
89        // a pointer to our specific cache implementation
90        Cache<TagStore> *cache;
91
92      protected:
93
94        virtual bool recvTimingSnoopResp(PacketPtr pkt);
95
96        virtual bool recvTimingReq(PacketPtr pkt);
97
98        virtual Tick recvAtomic(PacketPtr pkt);
99
100        virtual void recvFunctional(PacketPtr pkt);
101
102        virtual AddrRangeList getAddrRanges() const;
103
104      public:
105
106        CpuSidePort(const std::string &_name, Cache<TagStore> *_cache,
107                    const std::string &_label);
108
109    };
110
111    /**
112     * Override the default behaviour of sendDeferredPacket to enable
113     * the memory-side cache port to also send requests based on the
114     * current MSHR status. This queue has a pointer to our specific
115     * cache implementation and is used by the MemSidePort.
116     */
117    class MemSidePacketQueue : public MasterPacketQueue
118    {
119
120      protected:
121
122        Cache<TagStore> &cache;
123
124      public:
125
126        MemSidePacketQueue(Cache<TagStore> &cache, MasterPort &port,
127                           const std::string &label) :
128            MasterPacketQueue(cache, port, label), cache(cache) { }
129
130        /**
131         * Override the normal sendDeferredPacket and do not only
132         * consider the transmit list (used for responses), but also
133         * requests.
134         */
135        virtual void sendDeferredPacket();
136
137    };
138
139    /**
140     * The memory-side port extends the base cache master port with
141     * access functions for functional, atomic and timing snoops.
142     */
143    class MemSidePort : public CacheMasterPort
144    {
145      private:
146
147        /** The cache-specific queue. */
148        MemSidePacketQueue _queue;
149
150        // a pointer to our specific cache implementation
151        Cache<TagStore> *cache;
152
153      protected:
154
155        virtual void recvTimingSnoopReq(PacketPtr pkt);
156
157        virtual bool recvTimingResp(PacketPtr pkt);
158
159        virtual Tick recvAtomicSnoop(PacketPtr pkt);
160
161        virtual void recvFunctionalSnoop(PacketPtr pkt);
162
163      public:
164
165        MemSidePort(const std::string &_name, Cache<TagStore> *_cache,
166                    const std::string &_label);
167    };
168
169    /** Tag and data Storage */
170    TagStore *tags;
171
172    /** Prefetcher */
173    BasePrefetcher *prefetcher;
174
175    /** Temporary cache block for occasional transitory use */
176    BlkType *tempBlock;
177
178    /**
179     * This cache should allocate a block on a line-sized write miss.
180     */
181    const bool doFastWrites;
182
183    /**
184     * Notify the prefetcher on every access, not just misses.
185     */
186    const bool prefetchOnAccess;
187
188    /**
189     * @todo this is a temporary workaround until the 4-phase code is committed.
190     * upstream caches need this packet until true is returned, so hold it for
191     * deletion until a subsequent call
192     */
193    std::vector<PacketPtr> pendingDelete;
194
195    /**
196     * Does all the processing necessary to perform the provided request.
197     * @param pkt The memory request to perform.
198     * @param lat The latency of the access.
199     * @param writebacks List for any writebacks that need to be performed.
200     * @param update True if the replacement data should be updated.
201     * @return Boolean indicating whether the request was satisfied.
202     */
203    bool access(PacketPtr pkt, BlkType *&blk,
204                Cycles &lat, PacketList &writebacks);
205
206    /**
207     *Handle doing the Compare and Swap function for SPARC.
208     */
209    void cmpAndSwap(BlkType *blk, PacketPtr pkt);
210
211    /**
212     * Find a block frame for new block at address addr, assuming that
213     * the block is not currently in the cache.  Append writebacks if
214     * any to provided packet list.  Return free block frame.  May
215     * return NULL if there are no replaceable blocks at the moment.
216     */
217    BlkType *allocateBlock(Addr addr, PacketList &writebacks);
218
219    /**
220     * Populates a cache block and handles all outstanding requests for the
221     * satisfied fill request. This version takes two memory requests. One
222     * contains the fill data, the other is an optional target to satisfy.
223     * @param pkt The memory request with the fill data.
224     * @param blk The cache block if it already exists.
225     * @param writebacks List for any writebacks that need to be performed.
226     * @return Pointer to the new cache block.
227     */
228    BlkType *handleFill(PacketPtr pkt, BlkType *blk,
229                        PacketList &writebacks);
230
231
232    /**
233     * Performs the access specified by the request.
234     * @param pkt The request to perform.
235     * @return The result of the access.
236     */
237    bool recvTimingReq(PacketPtr pkt);
238
239    /**
240     * Handles a response (cache line fill/write ack) from the bus.
241     * @param pkt The response packet
242     */
243    void recvTimingResp(PacketPtr pkt);
244
245    /**
246     * Snoops bus transactions to maintain coherence.
247     * @param pkt The current bus transaction.
248     */
249    void recvTimingSnoopReq(PacketPtr pkt);
250
251    /**
252     * Handle a snoop response.
253     * @param pkt Snoop response packet
254     */
255    void recvTimingSnoopResp(PacketPtr pkt);
256
257    /**
258     * Performs the access specified by the request.
259     * @param pkt The request to perform.
260     * @return The number of ticks required for the access.
261     */
262    Tick recvAtomic(PacketPtr pkt);
263
264    /**
265     * Snoop for the provided request in the cache and return the estimated
266     * time taken.
267     * @param pkt The memory request to snoop
268     * @return The number of ticks required for the snoop.
269     */
270    Tick recvAtomicSnoop(PacketPtr pkt);
271
272    /**
273     * Performs the access specified by the request.
274     * @param pkt The request to perform.
275     * @param fromCpuSide from the CPU side port or the memory side port
276     */
277    void functionalAccess(PacketPtr pkt, bool fromCpuSide);
278
279    void satisfyCpuSideRequest(PacketPtr pkt, BlkType *blk,
280                               bool deferred_response = false,
281                               bool pending_downgrade = false);
282    bool satisfyMSHR(MSHR *mshr, PacketPtr pkt, BlkType *blk);
283
284    void doTimingSupplyResponse(PacketPtr req_pkt, uint8_t *blk_data,
285                                bool already_copied, bool pending_inval);
286
287    /**
288     * Sets the blk to the new state.
289     * @param blk The cache block being snooped.
290     * @param new_state The new coherence state for the block.
291     */
292    void handleSnoop(PacketPtr ptk, BlkType *blk,
293                     bool is_timing, bool is_deferred, bool pending_inval);
294
295    /**
296     * Create a writeback request for the given block.
297     * @param blk The block to writeback.
298     * @return The writeback request for the block.
299     */
300    PacketPtr writebackBlk(BlkType *blk);
301
302
303    void memWriteback();
304    void memInvalidate();
305    bool isDirty() const;
306
307    /**
308     * Cache block visitor that writes back dirty cache blocks using
309     * functional writes.
310     *
311     * \return Always returns true.
312     */
313    bool writebackVisitor(BlkType &blk);
314    /**
315     * Cache block visitor that invalidates all blocks in the cache.
316     *
317     * @warn Dirty cache lines will not be written back to memory.
318     *
319     * \return Always returns true.
320     */
321    bool invalidateVisitor(BlkType &blk);
322
323    /**
324     * Flush a cache line due to an uncacheable memory access to the
325     * line.
326     *
327     * @note This shouldn't normally happen, but we need to handle it
328     * since some architecture models don't implement cache
329     * maintenance operations. We won't even try to get a decent
330     * timing here since the line should have been flushed earlier by
331     * a cache maintenance operation.
332     */
333    void uncacheableFlush(PacketPtr pkt);
334
335    /**
336     * Squash all requests associated with specified thread.
337     * intended for use by I-cache.
338     * @param threadNum The thread to squash.
339     */
340    void squash(int threadNum);
341
342    /**
343     * Generate an appropriate downstream bus request packet for the
344     * given parameters.
345     * @param cpu_pkt  The upstream request that needs to be satisfied.
346     * @param blk The block currently in the cache corresponding to
347     * cpu_pkt (NULL if none).
348     * @param needsExclusive  Indicates that an exclusive copy is required
349     * even if the request in cpu_pkt doesn't indicate that.
350     * @return A new Packet containing the request, or NULL if the
351     * current request in cpu_pkt should just be forwarded on.
352     */
353    PacketPtr getBusPacket(PacketPtr cpu_pkt, BlkType *blk,
354                           bool needsExclusive) const;
355
356    /**
357     * Return the next MSHR to service, either a pending miss from the
358     * mshrQueue, a buffered write from the write buffer, or something
359     * from the prefetcher.  This function is responsible for
360     * prioritizing among those sources on the fly.
361     */
362    MSHR *getNextMSHR();
363
364    /**
365     * Selects an outstanding request to service.  Called when the
366     * cache gets granted the downstream bus in timing mode.
367     * @return The request to service, NULL if none found.
368     */
369    PacketPtr getTimingPacket();
370
371    /**
372     * Marks a request as in service (sent on the bus). This can have side
373     * effect since storage for no response commands is deallocated once they
374     * are successfully sent.
375     * @param pkt The request that was sent on the bus.
376     */
377    void markInService(MSHR *mshr, PacketPtr pkt = 0);
378
379    /**
380     * Return whether there are any outstanding misses.
381     */
382    bool outstandingMisses() const
383    {
384        return mshrQueue.allocated != 0;
385    }
386
387    CacheBlk *findBlock(Addr addr) const {
388        return tags->findBlock(addr);
389    }
390
391    bool inCache(Addr addr) const {
392        return (tags->findBlock(addr) != 0);
393    }
394
395    bool inMissQueue(Addr addr) const {
396        return (mshrQueue.findMatch(addr) != 0);
397    }
398
399    /**
400     * Find next request ready time from among possible sources.
401     */
402    Tick nextMSHRReadyTime() const;
403
404  public:
405    /** Instantiates a basic cache object. */
406    Cache(const Params *p);
407
408    /** Non-default destructor is needed to deallocate memory. */
409    virtual ~Cache();
410
411    void regStats();
412
413    /** serialize the state of the caches
414     * We currently don't support checkpointing cache state, so this panics.
415     */
416    virtual void serialize(std::ostream &os);
417    void unserialize(Checkpoint *cp, const std::string &section);
418};
419
420#endif // __CACHE_HH__
421