2 * Copyright (c) 2018 Inria
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.
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.
28 * Authors: Daniel Carvalho
33 * Definitions of a sector tag store.
36 #include "mem/cache/tags/sector_tags.hh"
42 #include "base/intmath.hh"
43 #include "base/logging.hh"
44 #include "base/types.hh"
45 #include "mem/cache/base.hh"
46 #include "mem/cache/replacement_policies/base.hh"
47 #include "mem/cache/tags/indexing_policies/base.hh"
49 SectorTags::SectorTags(const SectorTagsParams
*p
)
50 : BaseTags(p
), allocAssoc(p
->assoc
),
51 sequentialAccess(p
->sequential_access
),
52 replacementPolicy(p
->replacement_policy
),
53 numBlocksPerSector(p
->num_blocks_per_sector
),
54 numSectors(numBlocks
/ p
->num_blocks_per_sector
), blks(numBlocks
),
55 secBlks(numSectors
), sectorShift(floorLog2(blkSize
)),
56 sectorMask(numBlocksPerSector
- 1)
59 fatal_if(blkSize
< 4 || !isPowerOf2(blkSize
),
60 "Block size must be at least 4 and a power of 2");
61 fatal_if(!isPowerOf2(numBlocksPerSector
),
62 "# of blocks per sector must be non-zero and a power of 2");
66 SectorTags::init(BaseCache
* cache
)
71 // Initialize all blocks
72 unsigned blk_index
= 0; // index into blks array
73 for (unsigned sec_blk_index
= 0; sec_blk_index
< numSectors
;
76 // Locate next cache sector
77 SectorBlk
* sec_blk
= &secBlks
[sec_blk_index
];
79 // Link block to indexing policy
80 indexingPolicy
->setEntry(sec_blk
, sec_blk_index
);
82 // Associate a replacement data entry to the sector
83 sec_blk
->replacementData
= replacementPolicy
->instantiateEntry();
85 // Initialize all blocks in this sector
86 sec_blk
->blks
.resize(numBlocksPerSector
);
87 for (unsigned k
= 0; k
< numBlocksPerSector
; ++k
){
88 // Select block within the set to be linked
89 SectorSubBlk
*& blk
= sec_blk
->blks
[k
];
91 // Locate next cache block
92 blk
= &blks
[blk_index
];
94 // Associate a data chunk to the block
95 blk
->data
= &dataBlks
[blkSize
*blk_index
];
97 // Associate sector block to this block
98 blk
->setSectorBlock(sec_blk
);
100 // Associate the sector replacement data to this block
101 blk
->replacementData
= sec_blk
->replacementData
;
103 // Set its index and sector offset
104 blk
->setSectorOffset(k
);
106 // Update block index
113 SectorTags::invalidate(CacheBlk
*blk
)
115 BaseTags::invalidate(blk
);
117 // Get block's sector
118 SectorSubBlk
* sub_blk
= static_cast<SectorSubBlk
*>(blk
);
119 const SectorBlk
* sector_blk
= sub_blk
->getSectorBlock();
121 // When a block in a sector is invalidated, it does not make the tag
122 // invalid automatically, as there might be other blocks in the sector
123 // using it. The tag is invalidated only when there is a single block
125 if (!sector_blk
->isValid()) {
126 // Decrease the number of tags in use
129 // Invalidate replacement data, as we're invalidating the sector
130 replacementPolicy
->invalidate(sector_blk
->replacementData
);
135 SectorTags::accessBlock(Addr addr
, bool is_secure
, Cycles
&lat
)
137 CacheBlk
*blk
= findBlock(addr
, is_secure
);
139 // Access all tags in parallel, hence one in each way. The data side
140 // either accesses all blocks in parallel, or one block sequentially on
141 // a hit. Sequential access with a miss doesn't access data.
142 tagAccesses
+= allocAssoc
;
143 if (sequentialAccess
) {
144 if (blk
!= nullptr) {
148 dataAccesses
+= allocAssoc
*numBlocksPerSector
;
151 if (blk
!= nullptr) {
154 // Check if the block to be accessed is available. If not,
155 // apply the accessLatency on top of block->whenReady.
156 if (blk
->whenReady
> curTick() &&
157 cache
->ticksToCycles(blk
->whenReady
- curTick()) >
159 lat
= cache
->ticksToCycles(blk
->whenReady
- curTick()) +
163 // Update number of references to accessed block
166 // Get block's sector
167 SectorSubBlk
* sub_blk
= static_cast<SectorSubBlk
*>(blk
);
168 const SectorBlk
* sector_blk
= sub_blk
->getSectorBlock();
170 // Update replacement data of accessed block, which is shared with
171 // the whole sector it belongs to
172 replacementPolicy
->touch(sector_blk
->replacementData
);
182 SectorTags::insertBlock(const Addr addr
, const bool is_secure
,
183 const int src_master_ID
, const uint32_t task_ID
,
186 // Do common block insertion functionality
187 BaseTags::insertBlock(addr
, is_secure
, src_master_ID
, task_ID
, blk
);
189 // Get block's sector
190 SectorSubBlk
* sub_blk
= static_cast<SectorSubBlk
*>(blk
);
191 const SectorBlk
* sector_blk
= sub_blk
->getSectorBlock();
193 // When a block is inserted, the tag is only a newly used tag if the
194 // sector was not previously present in the cache.
195 // This assumes BaseTags::insertBlock does not set the valid bit.
196 if (sector_blk
->isValid()) {
197 // An existing entry's replacement data is just updated
198 replacementPolicy
->touch(sector_blk
->replacementData
);
200 // Increment tag counter
203 // A new entry resets the replacement data
204 replacementPolicy
->reset(sector_blk
->replacementData
);
209 SectorTags::findBlock(Addr addr
, bool is_secure
) const
211 // Extract sector tag
212 const Addr tag
= extractTag(addr
);
214 // The address can only be mapped to a specific location of a sector
215 // due to sectors being composed of contiguous-address entries
216 const Addr offset
= extractSectorOffset(addr
);
218 // Find all possible sector entries that may contain the given address
219 const std::vector
<ReplaceableEntry
*> entries
=
220 indexingPolicy
->getPossibleEntries(addr
);
223 for (const auto& sector
: entries
) {
224 auto blk
= static_cast<SectorBlk
*>(sector
)->blks
[offset
];
225 if (blk
->getTag() == tag
&& blk
->isValid() &&
226 blk
->isSecure() == is_secure
) {
231 // Did not find block
236 SectorTags::findVictim(Addr addr
, const bool is_secure
,
237 std::vector
<CacheBlk
*>& evict_blks
) const
239 // Get possible entries to be victimized
240 const std::vector
<ReplaceableEntry
*> sector_entries
=
241 indexingPolicy
->getPossibleEntries(addr
);
243 // Check if the sector this address belongs to has been allocated
244 Addr tag
= extractTag(addr
);
245 SectorBlk
* victim_sector
= nullptr;
246 for (const auto& sector
: sector_entries
) {
247 SectorBlk
* sector_blk
= static_cast<SectorBlk
*>(sector
);
248 if ((tag
== sector_blk
->getTag()) && sector_blk
->isValid() &&
249 (is_secure
== sector_blk
->isSecure())){
250 victim_sector
= sector_blk
;
255 // If the sector is not present
256 if (victim_sector
== nullptr){
257 // Choose replacement victim from replacement candidates
258 victim_sector
= static_cast<SectorBlk
*>(replacementPolicy
->getVictim(
262 // Get the entry of the victim block within the sector
263 SectorSubBlk
* victim
= victim_sector
->blks
[extractSectorOffset(addr
)];
265 // Get evicted blocks. Blocks are only evicted if the sectors mismatch and
266 // the currently existing sector is valid.
267 if ((tag
== victim_sector
->getTag()) &&
268 (is_secure
== victim_sector
->isSecure())){
269 // It would be a hit if victim was valid, and upgrades do not call
270 // findVictim, so it cannot happen
271 assert(!victim
->isValid());
273 // The whole sector must be evicted to make room for the new sector
274 for (const auto& blk
: victim_sector
->blks
){
275 evict_blks
.push_back(blk
);
283 SectorTags::extractSectorOffset(Addr addr
) const
285 return (addr
>> sectorShift
) & sectorMask
;
289 SectorTags::regenerateBlkAddr(const CacheBlk
* blk
) const
291 const SectorSubBlk
* blk_cast
= static_cast<const SectorSubBlk
*>(blk
);
292 const SectorBlk
* sec_blk
= blk_cast
->getSectorBlock();
293 const Addr sec_addr
= indexingPolicy
->regenerateAddr(blk
->tag
, sec_blk
);
294 return sec_addr
| ((Addr
)blk_cast
->getSectorOffset() << sectorShift
);
298 SectorTags::forEachBlk(std::function
<void(CacheBlk
&)> visitor
)
300 for (SectorSubBlk
& blk
: blks
) {
306 SectorTags::anyBlk(std::function
<bool(CacheBlk
&)> visitor
)
308 for (SectorSubBlk
& blk
: blks
) {
317 SectorTagsParams::create()
319 // There must be a indexing policy
320 fatal_if(!indexing_policy
, "An indexing policy is required");
322 return new SectorTags(this);