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;

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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 * Definitions of a sector tag store.
34 */
35
36#include "mem/cache/tags/sector_tags.hh"
37
38#include <cassert>
39#include <memory>
40#include <string>
41
42#include "base/intmath.hh"
43#include "base/logging.hh"
44#include "base/types.hh"
45#include "debug/CacheRepl.hh"
46#include "mem/cache/base.hh"
47#include "mem/cache/replacement_policies/base.hh"
48#include "mem/cache/tags/indexing_policies/base.hh"
49
50SectorTags::SectorTags(const SectorTagsParams *p)
51 : BaseTags(p), allocAssoc(p->assoc),
52 sequentialAccess(p->sequential_access),
53 replacementPolicy(p->replacement_policy),
54 numBlocksPerSector(p->num_blocks_per_sector),
55 numSectors(numBlocks / p->num_blocks_per_sector), blks(numBlocks),
56 secBlks(numSectors), sectorShift(floorLog2(blkSize)),
57 sectorMask(numBlocksPerSector - 1)
58{
59 // Check parameters
60 fatal_if(blkSize < 4 || !isPowerOf2(blkSize),
61 "Block size must be at least 4 and a power of 2");
62 fatal_if(!isPowerOf2(numBlocksPerSector),
63 "# of blocks per sector must be non-zero and a power of 2");
64}
65
66void
67SectorTags::init(BaseCache* cache)
68{
69 // Set parent cache
70 setCache(cache);
71
72 // Initialize all blocks
73 unsigned blk_index = 0; // index into blks array
74 for (unsigned sec_blk_index = 0; sec_blk_index < numSectors;
75 sec_blk_index++)
76 {
77 // Locate next cache sector
78 SectorBlk* sec_blk = &secBlks[sec_blk_index];
79
80 // Link block to indexing policy
81 indexingPolicy->setEntry(sec_blk, sec_blk_index);
82
83 // Associate a replacement data entry to the sector
84 sec_blk->replacementData = replacementPolicy->instantiateEntry();
85
86 // Initialize all blocks in this sector
87 sec_blk->blks.resize(numBlocksPerSector);
88 for (unsigned k = 0; k < numBlocksPerSector; ++k){
89 // Select block within the set to be linked
90 SectorSubBlk*& blk = sec_blk->blks[k];
91
92 // Locate next cache block
93 blk = &blks[blk_index];
94
95 // Associate a data chunk to the block
96 blk->data = &dataBlks[blkSize*blk_index];
97
98 // Associate sector block to this block
99 blk->setSectorBlock(sec_blk);
100
101 // Associate the sector replacement data to this block
102 blk->replacementData = sec_blk->replacementData;
103
104 // Set its index and sector offset
105 blk->setSectorOffset(k);
106
107 // Update block index
108 ++blk_index;
109 }
110 }
111}
112
113void
114SectorTags::invalidate(CacheBlk *blk)
115{
116 BaseTags::invalidate(blk);

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174 } else {
175 // If a cache miss
176 lat = lookupLatency;
177 }
178
179 return blk;
180}
181
182void
183SectorTags::insertBlock(const Addr addr, const bool is_secure,
184 const int src_master_ID, const uint32_t task_ID,
185 CacheBlk *blk)
186{
187 // Do common block insertion functionality
188 BaseTags::insertBlock(addr, is_secure, src_master_ID, task_ID, blk);
189

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211{
212 // Extract sector tag
213 const Addr tag = extractTag(addr);
214
215 // The address can only be mapped to a specific location of a sector
216 // due to sectors being composed of contiguous-address entries
217 const Addr offset = extractSectorOffset(addr);
218
219 // Find all possible sector entries that may contain the given address
220 const std::vector<ReplaceableEntry*> entries =
221 indexingPolicy->getPossibleEntries(addr);
222
223 // Search for block
224 for (const auto& sector : entries) {
225 auto blk = static_cast<SectorBlk*>(sector)->blks[offset];
226 if (blk->getTag() == tag && blk->isValid() &&
227 blk->isSecure() == is_secure) {
228 return blk;
229 }
230 }
231
232 // Did not find block
233 return nullptr;
234}
235
236CacheBlk*
237SectorTags::findVictim(Addr addr, const bool is_secure,
238 std::vector<CacheBlk*>& evict_blks) const
239{
240 // Get possible entries to be victimized
241 const std::vector<ReplaceableEntry*> sector_entries =
242 indexingPolicy->getPossibleEntries(addr);
243
244 // Check if the sector this address belongs to has been allocated
245 Addr tag = extractTag(addr);
246 SectorBlk* victim_sector = nullptr;
247 for (const auto& sector : sector_entries) {
248 SectorBlk* sector_blk = static_cast<SectorBlk*>(sector);
249 if ((tag == sector_blk->getTag()) && sector_blk->isValid() &&
250 (is_secure == sector_blk->isSecure())){
251 victim_sector = sector_blk;
252 break;
253 }
254 }
255
256 // If the sector is not present
257 if (victim_sector == nullptr){
258 // Choose replacement victim from replacement candidates
259 victim_sector = static_cast<SectorBlk*>(replacementPolicy->getVictim(
260 sector_entries));
261 }
262
263 // Get the entry of the victim block within the sector
264 SectorSubBlk* victim = victim_sector->blks[extractSectorOffset(addr)];
265
266 // Get evicted blocks. Blocks are only evicted if the sectors mismatch and
267 // the currently existing sector is valid.
268 if ((tag == victim_sector->getTag()) &&
269 (is_secure == victim_sector->isSecure())){
270 // It would be a hit if victim was valid, and upgrades do not call
271 // findVictim, so it cannot happen

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279
280 DPRINTF(CacheRepl, "set %x, way %x, sector offset %x: selecting blk " \
281 "for replacement\n", victim->getSet(), victim->getWay(),
282 victim->getSectorOffset());
283
284 return victim;
285}
286
287int
288SectorTags::extractSectorOffset(Addr addr) const
289{
290 return (addr >> sectorShift) & sectorMask;
291}
292
293Addr
294SectorTags::regenerateBlkAddr(const CacheBlk* blk) const
295{
296 const SectorSubBlk* blk_cast = static_cast<const SectorSubBlk*>(blk);
297 const SectorBlk* sec_blk = blk_cast->getSectorBlock();
298 const Addr sec_addr = indexingPolicy->regenerateAddr(blk->tag, sec_blk);
299 return sec_addr | ((Addr)blk_cast->getSectorOffset() << sectorShift);
300}
301
302void
303SectorTags::forEachBlk(std::function<void(CacheBlk &)> visitor)
304{
305 for (SectorSubBlk& blk : blks) {
306 visitor(blk);
307 }

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316 }
317 }
318 return false;
319}
320
321SectorTags *
322SectorTagsParams::create()
323{
324 // There must be a indexing policy
325 fatal_if(!indexing_policy, "An indexing policy is required");
326
327 return new SectorTags(this);
328}