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 tag store.
34 */
35
36#ifndef __MEM_CACHE_TAGS_SECTOR_TAGS_HH__
37#define __MEM_CACHE_TAGS_SECTOR_TAGS_HH__
38
39#include <cstdint>
40#include <string>
41#include <vector>
42
43#include "mem/cache/tags/base.hh"
44#include "mem/cache/tags/sector_blk.hh"
45#include "mem/packet.hh"
46#include "params/SectorTags.hh"
47
48class BaseReplacementPolicy;
49class ReplaceableEntry;
50
51/**
52 * A SectorTags cache tag store.
53 * @sa  \ref gem5MemorySystem "gem5 Memory System"
54 *
55 * The SectorTags placement policy divides the cache into s sectors of w
56 * consecutive sectors (ways). Each sector then consists of a number of
57 * sequential cache lines that may or may not be present.
58 */
59class SectorTags : public BaseTags
60{
61  private:
62    /** The cache blocks. */
63    std::vector<SectorSubBlk> blks;
64    /** The cache sector blocks. */
65    std::vector<SectorBlk> secBlks;
66
67  protected:
68    /** The allocatable associativity of the cache (alloc mask). */
69    unsigned allocAssoc;
70
71    /** Whether tags and data are accessed sequentially. */
72    const bool sequentialAccess;
73
74    /** Replacement policy */
75    BaseReplacementPolicy *replacementPolicy;
76
77    /** Number of data blocks per sector. */
78    const unsigned numBlocksPerSector;
79
80    /** The number of sectors in the cache. */
81    const unsigned numSectors;
82
83    // Organization of an address:
84    // Tag | Placement Location | Sector Offset # | Offset #
85    /** The amount to shift the address to get the sector tag. */
86    const int sectorShift;
87
88    /** Mask out all bits that aren't part of the sector tag. */
89    const unsigned sectorMask;
90
91  public:
92    /** Convenience typedef. */
93     typedef SectorTagsParams Params;
94
95    /**
96     * Construct and initialize this tag store.
97     */
98    SectorTags(const Params *p);
99
100    /**
101     * Destructor.
102     */
103    virtual ~SectorTags() {};
104
105    /**
106     * Initialize blocks as SectorBlk and SectorSubBlk instances.
107     */
108    void tagsInit() override;
109
110    /**
111     * This function updates the tags when a block is invalidated but does
112     * not invalidate the block itself. It also updates the replacement data.
113     *
114     * @param blk The block to invalidate.
115     */
116    void invalidate(CacheBlk *blk) override;
117
118    /**
119     * Access block and update replacement data. May not succeed, in which
120     * case nullptr is returned. This has all the implications of a cache
121     * access and should only be used as such. Returns the tag lookup latency
122     * as a side effect.
123     *
124     * @param addr The address to find.
125     * @param is_secure True if the target memory space is secure.
126     * @param lat The latency of the tag lookup.
127     * @return Pointer to the cache block if found.
128     */
129    CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) override;
130
131    /**
132     * Insert the new block into the cache and update replacement data.
133     *
134     * @param pkt Packet holding the address to update
135     * @param blk The block to update.
136     */
137    void insertBlock(const PacketPtr pkt, CacheBlk *blk) override;
138
139    /**
140     * Finds the given address in the cache, do not update replacement data.
141     * i.e. This is a no-side-effect find of a block.
142     *
143     * @param addr The address to find.
144     * @param is_secure True if the target memory space is secure.
145     * @return Pointer to the cache block if found.
146     */
147    CacheBlk* findBlock(Addr addr, bool is_secure) const override;
148
149    /**
150     * Find replacement victim based on address.
151     *
152     * @param addr Address to find a victim for.
153     * @param is_secure True if the target memory space is secure.
154     * @param size Size, in bits, of new block to allocate.
155     * @param evict_blks Cache blocks to be evicted.
156     * @return Cache block to be replaced.
157     */
158    CacheBlk* findVictim(Addr addr, const bool is_secure,
159                         const std::size_t size,
160                         std::vector<CacheBlk*>& evict_blks) const override;
161
162    /**
163     * Calculate a block's offset in a sector from the address.
164     *
165     * @param addr The address to get the offset from.
166     * @return Offset of the corresponding block within its sector.
167     */
168    int extractSectorOffset(Addr addr) const;
169
170    /**
171     * Regenerate the block address from the tag and location.
172     *
173     * @param block The block.
174     * @return the block address.
175     */
176    Addr regenerateBlkAddr(const CacheBlk* blk) const override;
177
178    /**
179     * Visit each sub-block in the tags and apply a visitor.
180     *
181     * The visitor should be a std::function that takes a cache block.
182     * reference as its parameter.
183     *
184     * @param visitor Visitor to call on each block.
185     */
186    void forEachBlk(std::function<void(CacheBlk &)> visitor) override;
187
188    /**
189     * Find if any of the sub-blocks satisfies a condition.
190     *
191     * The visitor should be a std::function that takes a cache block
192     * reference as its parameter. The visitor will terminate the
193     * traversal early if the condition is satisfied.
194     *
195     * @param visitor Visitor to call on each block.
196     */
197    bool anyBlk(std::function<bool(CacheBlk &)> visitor) override;
198};
199
200#endif //__MEM_CACHE_TAGS_SECTOR_TAGS_HH__
201