sector_tags.hh revision 12773:387fa9e5c9ff 
1/*
2 * Copyright (c) 2018 Inria
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Daniel Carvalho
29 */
30
31/**
32 * @file
33 * Declaration of a sector set associative tag store.
34 */
35
36#ifndef __MEM_CACHE_TAGS_SECTOR_TAGS_HH__
37#define __MEM_CACHE_TAGS_SECTOR_TAGS_HH__
38
39#include <string>
40#include <vector>
41
42#include "mem/cache/sector_blk.hh"
43#include "mem/cache/tags/base.hh"
44#include "mem/packet.hh"
45#include "params/SectorTags.hh"
46
47class BaseReplacementPolicy;
48class ReplaceableEntry;
49
50/**
51 * A SectorTags cache tag store.
52 * @sa  \ref gem5MemorySystem "gem5 Memory System"
53 *
54 * The SectorTags placement policy divides the cache into s sectors of w
55 * consecutive sectors (ways). Each sector then consists of a number of
56 * sequential cache lines that may or may not be present.
57 */
58class SectorTags : public BaseTags
59{
60  protected:
61    /** Typedef the set type used in this tag store. */
62    typedef std::vector<SectorBlk*> SetType;
63
64    /** The associativity of the cache. */
65    const unsigned assoc;
66    /** The allocatable associativity of the cache (alloc mask). */
67    unsigned allocAssoc;
68
69    /** Whether tags and data are accessed sequentially. */
70    const bool sequentialAccess;
71
72    /** Replacement policy */
73    BaseReplacementPolicy *replacementPolicy;
74
75    /** Number of data blocks per sector. */
76    const unsigned numBlocksPerSector;
77
78    /** The number of sectors in the cache. */
79    const unsigned numSectors;
80    /** The number of sets in the cache. */
81    const unsigned numSets;
82
83    /** The cache blocks. */
84    std::vector<SectorSubBlk> blks;
85    /** The cache sector blocks. */
86    std::vector<SectorBlk> secBlks;
87    /** The cache sets. */
88    std::vector<SetType> sets;
89
90    // Organization of an address: Tag | Set # | Sector Offset # | Offset #
91    /** The amount to shift the address to get the sector tag. */
92    const int sectorShift;
93    /** The amount to shift the address to get the set. */
94    const int setShift;
95    /** The amount to shift the address to get the tag. */
96    const int tagShift;
97
98    /** Mask out all bits that aren't part of the sector tag. */
99    const unsigned sectorMask;
100    /** Mask out all bits that aren't part of the set index. */
101    const unsigned setMask;
102
103  public:
104    /** Convenience typedef. */
105     typedef SectorTagsParams Params;
106
107    /**
108     * Construct and initialize this tag store.
109     */
110    SectorTags(const Params *p);
111
112    /**
113     * Destructor.
114     */
115    virtual ~SectorTags() {};
116
117    /**
118     * This function updates the tags when a block is invalidated but does
119     * not invalidate the block itself. It also updates the replacement data.
120     *
121     * @param blk The block to invalidate.
122     */
123    void invalidate(CacheBlk *blk) override;
124
125    /**
126     * Access block and update replacement data. May not succeed, in which
127     * case nullptr is returned. This has all the implications of a cache
128     * access and should only be used as such. Returns the access latency
129     * as a side effect.
130     *
131     * @param addr The address to find.
132     * @param is_secure True if the target memory space is secure.
133     * @param lat The access latency.
134     * @return Pointer to the cache block if found.
135     */
136    CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) override;
137
138    /**
139     * Find all possible block locations for insertion and replacement of
140     * an address. Should be called immediately before ReplacementPolicy's
141     * findVictim() not to break cache resizing.
142     * Returns sector blocks in all ways belonging to the set of the address.
143     *
144     * @param addr The addr to a find possible locations for.
145     * @return The possible locations.
146     */
147    virtual const std::vector<SectorBlk*> getPossibleLocations(Addr addr)
148                                                                   const;
149
150    /**
151     * Insert the new block into the cache and update replacement data.
152     *
153     * @param pkt Packet holding the address to update
154     * @param blk The block to update.
155     */
156    void insertBlock(const PacketPtr pkt, CacheBlk *blk) override;
157
158    /**
159     * Finds the given address in the cache, do not update replacement data.
160     * i.e. This is a no-side-effect find of a block.
161     *
162     * @param addr The address to find.
163     * @param is_secure True if the target memory space is secure.
164     * @return Pointer to the cache block if found.
165     */
166    CacheBlk* findBlock(Addr addr, bool is_secure) const override;
167
168    /**
169     * Find a sector block given set and way.
170     *
171     * @param set The set of the block.
172     * @param way The way of the block.
173     * @return The block.
174     */
175    ReplaceableEntry* findBlockBySetAndWay(int set, int way) const override;
176
177    /**
178     * Find replacement victim based on address.
179     *
180     * @param addr Address to find a victim for.
181     * @param is_secure True if the target memory space is secure.
182     * @param evict_blks Cache blocks to be evicted.
183     * @return Cache block to be replaced.
184     */
185    CacheBlk* findVictim(Addr addr, const bool is_secure,
186                         std::vector<CacheBlk*>& evict_blks) const override;
187
188    /**
189     * Generate the sector tag from the given address.
190     *
191     * @param addr The address to get the sector tag from.
192     * @return The sector tag of the address.
193     */
194    Addr extractTag(Addr addr) const override;
195
196    /**
197     * Calculate the set index from the address.
198     *
199     * @param addr The address to get the set from.
200     * @return The set index of the address.
201     */
202    int extractSet(Addr addr) const;
203
204    /**
205     * Calculate a block's offset in a sector from the address.
206     *
207     * @param addr The address to get the offset from.
208     * @return Offset of the corresponding block within its sector.
209     */
210    int extractSectorOffset(Addr addr) const;
211
212    /**
213     * Regenerate the block address from the tag and set.
214     *
215     * @param block The block.
216     * @return the block address.
217     */
218    Addr regenerateBlkAddr(const CacheBlk* blk) const override;
219
220    /**
221     * Visit each sub-block in the tags and apply a visitor.
222     *
223     * The visitor should be a std::function that takes a cache block.
224     * reference as its parameter.
225     *
226     * @param visitor Visitor to call on each block.
227     */
228    void forEachBlk(std::function<void(CacheBlk &)> visitor) override;
229
230    /**
231     * Find if any of the sub-blocks satisfies a condition.
232     *
233     * The visitor should be a std::function that takes a cache block
234     * reference as its parameter. The visitor will terminate the
235     * traversal early if the condition is satisfied.
236     *
237     * @param visitor Visitor to call on each block.
238     */
239    bool anyBlk(std::function<bool(CacheBlk &)> visitor) override;
240};
241
242#endif //__MEM_CACHE_TAGS_SECTOR_TAGS_HH__
243