src/mem/cache/tags/sector_tags.cc - testing/jenkins-gem5-prod - Git at Google

 /*
  * Copyright (c) 2018 Inria
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met: redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer;
  * redistributions in binary form must reproduce the above copyright
  * notice, this list of conditions and the following disclaimer in the
  * documentation and/or other materials provided with the distribution;
  * neither the name of the copyright holders nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Authors: Daniel Carvalho
  */

 /**
  * @file
  * Definitions of a sector tag store.
  */

 #include "mem/cache/tags/sector_tags.hh"

 #include <cassert>
 #include <memory>
 #include <string>

 #include "base/intmath.hh"
 #include "base/logging.hh"
 #include "base/types.hh"
 #include "mem/cache/base.hh"
 #include "mem/cache/replacement_policies/base.hh"
 #include "mem/cache/replacement_policies/replaceable_entry.hh"
 #include "mem/cache/tags/indexing_policies/base.hh"

 SectorTags::SectorTags(const SectorTagsParams *p)
     : BaseTags(p), allocAssoc(p->assoc),
       sequentialAccess(p->sequential_access),
       replacementPolicy(p->replacement_policy),
       numBlocksPerSector(p->num_blocks_per_sector),
       numSectors(numBlocks / p->num_blocks_per_sector), blks(numBlocks),
       secBlks(numSectors), sectorShift(floorLog2(blkSize)),
       sectorMask(numBlocksPerSector - 1)
 {
     // Check parameters
     fatal_if(blkSize < 4 || !isPowerOf2(blkSize),
              "Block size must be at least 4 and a power of 2");
     fatal_if(!isPowerOf2(numBlocksPerSector),
              "# of blocks per sector must be non-zero and a power of 2");
 }

 void
 SectorTags::tagsInit()
 {
     // Initialize all blocks
     unsigned blk_index = 0;       // index into blks array
     for (unsigned sec_blk_index = 0; sec_blk_index < numSectors;
          sec_blk_index++)
     {
         // Locate next cache sector
         SectorBlk* sec_blk = &secBlks[sec_blk_index];

         // Link block to indexing policy
         indexingPolicy->setEntry(sec_blk, sec_blk_index);

         // Associate a replacement data entry to the sector
         sec_blk->replacementData = replacementPolicy->instantiateEntry();

         // Initialize all blocks in this sector
         sec_blk->blks.resize(numBlocksPerSector);
         for (unsigned k = 0; k < numBlocksPerSector; ++k){
             // Select block within the set to be linked
             SectorSubBlk*& blk = sec_blk->blks[k];

             // Locate next cache block
             blk = &blks[blk_index];

             // Associate a data chunk to the block
             blk->data = &dataBlks[blkSize*blk_index];

             // Associate sector block to this block
             blk->setSectorBlock(sec_blk);

             // Associate the sector replacement data to this block
             blk->replacementData = sec_blk->replacementData;

             // Set its index and sector offset
             blk->setSectorOffset(k);

             // Update block index
             ++blk_index;
         }
     }
 }

 void
 SectorTags::invalidate(CacheBlk *blk)
 {
     BaseTags::invalidate(blk);

     // Get block's sector
     SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk);
     const SectorBlk* sector_blk = sub_blk->getSectorBlock();

     // When a block in a sector is invalidated, it does not make the tag
     // invalid automatically, as there might be other blocks in the sector
     // using it. The tag is invalidated only when there is a single block
     // in the sector.
     if (!sector_blk->isValid()) {
         // Decrease the number of tags in use
         tagsInUse--;

         // Invalidate replacement data, as we're invalidating the sector
         replacementPolicy->invalidate(sector_blk->replacementData);
     }
 }

 CacheBlk*
 SectorTags::accessBlock(Addr addr, bool is_secure, Cycles &lat)
 {
     CacheBlk *blk = findBlock(addr, is_secure);

     // Access all tags in parallel, hence one in each way.  The data side
     // either accesses all blocks in parallel, or one block sequentially on
     // a hit.  Sequential access with a miss doesn't access data.
     tagAccesses += allocAssoc;
     if (sequentialAccess) {
         if (blk != nullptr) {
             dataAccesses += 1;
         }
     } else {
         dataAccesses += allocAssoc*numBlocksPerSector;
     }

     // If a cache hit
     if (blk != nullptr) {
         // Update number of references to accessed block
         blk->refCount++;

         // Get block's sector
         SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk);
         const SectorBlk* sector_blk = sub_blk->getSectorBlock();

         // Update replacement data of accessed block, which is shared with
         // the whole sector it belongs to
         replacementPolicy->touch(sector_blk->replacementData);
     }

     // The tag lookup latency is the same for a hit or a miss
     lat = lookupLatency;

     return blk;
 }

 void
 SectorTags::insertBlock(const Addr addr, const bool is_secure,
                         const int src_master_ID, const uint32_t task_ID,
                         CacheBlk *blk)
 {
     // Get block's sector
     SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk);
     const SectorBlk* sector_blk = sub_blk->getSectorBlock();

     // When a block is inserted, the tag is only a newly used tag if the
     // sector was not previously present in the cache.
     if (sector_blk->isValid()) {
         // An existing entry's replacement data is just updated
         replacementPolicy->touch(sector_blk->replacementData);
     } else {
         // Increment tag counter
         tagsInUse++;

         // A new entry resets the replacement data
         replacementPolicy->reset(sector_blk->replacementData);
     }

     // Do common block insertion functionality
     BaseTags::insertBlock(addr, is_secure, src_master_ID, task_ID, blk);
 }

 CacheBlk*
 SectorTags::findBlock(Addr addr, bool is_secure) const
 {
     // Extract sector tag
     const Addr tag = extractTag(addr);

     // The address can only be mapped to a specific location of a sector
     // due to sectors being composed of contiguous-address entries
     const Addr offset = extractSectorOffset(addr);

     // Find all possible sector entries that may contain the given address
     const std::vector<ReplaceableEntry*> entries =
         indexingPolicy->getPossibleEntries(addr);

     // Search for block
     for (const auto& sector : entries) {
         auto blk = static_cast<SectorBlk*>(sector)->blks[offset];
         if (blk->getTag() == tag && blk->isValid() &&
             blk->isSecure() == is_secure) {
             return blk;
         }
     }

     // Did not find block
     return nullptr;
 }

 CacheBlk*
 SectorTags::findVictim(Addr addr, const bool is_secure,
                        std::vector<CacheBlk*>& evict_blks) const
 {
     // Get possible entries to be victimized
     const std::vector<ReplaceableEntry*> sector_entries =
         indexingPolicy->getPossibleEntries(addr);

     // Check if the sector this address belongs to has been allocated
     Addr tag = extractTag(addr);
     SectorBlk* victim_sector = nullptr;
     for (const auto& sector : sector_entries) {
         SectorBlk* sector_blk = static_cast<SectorBlk*>(sector);
         if ((tag == sector_blk->getTag()) && sector_blk->isValid() &&
             (is_secure == sector_blk->isSecure())){
             victim_sector = sector_blk;
             break;
         }
     }

     // If the sector is not present
     if (victim_sector == nullptr){
         // Choose replacement victim from replacement candidates
         victim_sector = static_cast<SectorBlk*>(replacementPolicy->getVictim(
                                                 sector_entries));
     }

     // Get the entry of the victim block within the sector
     SectorSubBlk* victim = victim_sector->blks[extractSectorOffset(addr)];

     // Get evicted blocks. Blocks are only evicted if the sectors mismatch and
     // the currently existing sector is valid.
     if ((tag == victim_sector->getTag()) &&
         (is_secure == victim_sector->isSecure())){
         // It would be a hit if victim was valid, and upgrades do not call
         // findVictim, so it cannot happen
         assert(!victim->isValid());
     } else {
         // The whole sector must be evicted to make room for the new sector
         for (const auto& blk : victim_sector->blks){
             evict_blks.push_back(blk);
         }
     }

     return victim;
 }

 int
 SectorTags::extractSectorOffset(Addr addr) const
 {
     return (addr >> sectorShift) & sectorMask;
 }

 Addr
 SectorTags::regenerateBlkAddr(const CacheBlk* blk) const
 {
     const SectorSubBlk* blk_cast = static_cast<const SectorSubBlk*>(blk);
     const SectorBlk* sec_blk = blk_cast->getSectorBlock();
     const Addr sec_addr = indexingPolicy->regenerateAddr(blk->tag, sec_blk);
     return sec_addr | ((Addr)blk_cast->getSectorOffset() << sectorShift);
 }

 void
 SectorTags::forEachBlk(std::function<void(CacheBlk &)> visitor)
 {
     for (SectorSubBlk& blk : blks) {
         visitor(blk);
     }
 }

 bool
 SectorTags::anyBlk(std::function<bool(CacheBlk &)> visitor)
 {
     for (SectorSubBlk& blk : blks) {
         if (visitor(blk)) {
             return true;
         }
     }
     return false;
 }

 SectorTags *
 SectorTagsParams::create()
 {
     // There must be a indexing policy
     fatal_if(!indexing_policy, "An indexing policy is required");

     return new SectorTags(this);
 }
	/*
	* Copyright (c) 2018 Inria
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met: redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer;
	* redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution;
	* neither the name of the copyright holders nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* Authors: Daniel Carvalho
	*/

	/**
	* @file
	* Definitions of a sector tag store.
	*/

	#include "mem/cache/tags/sector_tags.hh"

	#include <cassert>
	#include <memory>
	#include <string>

	#include "base/intmath.hh"
	#include "base/logging.hh"
	#include "base/types.hh"
	#include "mem/cache/base.hh"
	#include "mem/cache/replacement_policies/base.hh"
	#include "mem/cache/replacement_policies/replaceable_entry.hh"
	#include "mem/cache/tags/indexing_policies/base.hh"

	SectorTags::SectorTags(const SectorTagsParams *p)
	: BaseTags(p), allocAssoc(p->assoc),
	sequentialAccess(p->sequential_access),
	replacementPolicy(p->replacement_policy),
	numBlocksPerSector(p->num_blocks_per_sector),
	numSectors(numBlocks / p->num_blocks_per_sector), blks(numBlocks),
	secBlks(numSectors), sectorShift(floorLog2(blkSize)),
	sectorMask(numBlocksPerSector - 1)
	{
	// Check parameters
	fatal_if(blkSize < 4 \|\| !isPowerOf2(blkSize),
	"Block size must be at least 4 and a power of 2");
	fatal_if(!isPowerOf2(numBlocksPerSector),
	"# of blocks per sector must be non-zero and a power of 2");
	}

	void
	SectorTags::tagsInit()
	{
	// Initialize all blocks
	unsigned blk_index = 0; // index into blks array
	for (unsigned sec_blk_index = 0; sec_blk_index < numSectors;
	sec_blk_index++)
	{
	// Locate next cache sector
	SectorBlk* sec_blk = &secBlks[sec_blk_index];

	// Link block to indexing policy
	indexingPolicy->setEntry(sec_blk, sec_blk_index);

	// Associate a replacement data entry to the sector
	sec_blk->replacementData = replacementPolicy->instantiateEntry();

	// Initialize all blocks in this sector
	sec_blk->blks.resize(numBlocksPerSector);
	for (unsigned k = 0; k < numBlocksPerSector; ++k){
	// Select block within the set to be linked
	SectorSubBlk*& blk = sec_blk->blks[k];

	// Locate next cache block
	blk = &blks[blk_index];

	// Associate a data chunk to the block
	blk->data = &dataBlks[blkSize*blk_index];

	// Associate sector block to this block
	blk->setSectorBlock(sec_blk);

	// Associate the sector replacement data to this block
	blk->replacementData = sec_blk->replacementData;

	// Set its index and sector offset
	blk->setSectorOffset(k);

	// Update block index
	++blk_index;
	}
	}
	}

	void
	SectorTags::invalidate(CacheBlk *blk)
	{
	BaseTags::invalidate(blk);

	// Get block's sector
	SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk);
	const SectorBlk* sector_blk = sub_blk->getSectorBlock();

	// When a block in a sector is invalidated, it does not make the tag
	// invalid automatically, as there might be other blocks in the sector
	// using it. The tag is invalidated only when there is a single block
	// in the sector.
	if (!sector_blk->isValid()) {
	// Decrease the number of tags in use
	tagsInUse--;

	// Invalidate replacement data, as we're invalidating the sector
	replacementPolicy->invalidate(sector_blk->replacementData);
	}
	}

	CacheBlk*
	SectorTags::accessBlock(Addr addr, bool is_secure, Cycles &lat)
	{
	CacheBlk *blk = findBlock(addr, is_secure);

	// Access all tags in parallel, hence one in each way. The data side
	// either accesses all blocks in parallel, or one block sequentially on
	// a hit. Sequential access with a miss doesn't access data.
	tagAccesses += allocAssoc;
	if (sequentialAccess) {
	if (blk != nullptr) {
	dataAccesses += 1;
	}
	} else {
	dataAccesses += allocAssoc*numBlocksPerSector;
	}

	// If a cache hit
	if (blk != nullptr) {
	// Update number of references to accessed block
	blk->refCount++;

	// Get block's sector
	SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk);
	const SectorBlk* sector_blk = sub_blk->getSectorBlock();

	// Update replacement data of accessed block, which is shared with
	// the whole sector it belongs to
	replacementPolicy->touch(sector_blk->replacementData);
	}

	// The tag lookup latency is the same for a hit or a miss
	lat = lookupLatency;

	return blk;
	}

	void
	SectorTags::insertBlock(const Addr addr, const bool is_secure,
	const int src_master_ID, const uint32_t task_ID,
	CacheBlk *blk)
	{
	// Get block's sector
	SectorSubBlk* sub_blk = static_cast<SectorSubBlk*>(blk);
	const SectorBlk* sector_blk = sub_blk->getSectorBlock();

	// When a block is inserted, the tag is only a newly used tag if the
	// sector was not previously present in the cache.
	if (sector_blk->isValid()) {
	// An existing entry's replacement data is just updated
	replacementPolicy->touch(sector_blk->replacementData);
	} else {
	// Increment tag counter
	tagsInUse++;

	// A new entry resets the replacement data
	replacementPolicy->reset(sector_blk->replacementData);
	}

	// Do common block insertion functionality
	BaseTags::insertBlock(addr, is_secure, src_master_ID, task_ID, blk);
	}

	CacheBlk*
	SectorTags::findBlock(Addr addr, bool is_secure) const
	{
	// Extract sector tag
	const Addr tag = extractTag(addr);

	// The address can only be mapped to a specific location of a sector
	// due to sectors being composed of contiguous-address entries
	const Addr offset = extractSectorOffset(addr);

	// Find all possible sector entries that may contain the given address
	const std::vector<ReplaceableEntry*> entries =
	indexingPolicy->getPossibleEntries(addr);

	// Search for block
	for (const auto& sector : entries) {
	auto blk = static_cast<SectorBlk*>(sector)->blks[offset];
	if (blk->getTag() == tag && blk->isValid() &&
	blk->isSecure() == is_secure) {
	return blk;
	}
	}

	// Did not find block
	return nullptr;
	}

	CacheBlk*
	SectorTags::findVictim(Addr addr, const bool is_secure,
	std::vector<CacheBlk*>& evict_blks) const
	{
	// Get possible entries to be victimized
	const std::vector<ReplaceableEntry*> sector_entries =
	indexingPolicy->getPossibleEntries(addr);

	// Check if the sector this address belongs to has been allocated
	Addr tag = extractTag(addr);
	SectorBlk* victim_sector = nullptr;
	for (const auto& sector : sector_entries) {
	SectorBlk* sector_blk = static_cast<SectorBlk*>(sector);
	if ((tag == sector_blk->getTag()) && sector_blk->isValid() &&
	(is_secure == sector_blk->isSecure())){
	victim_sector = sector_blk;
	break;
	}
	}

	// If the sector is not present
	if (victim_sector == nullptr){
	// Choose replacement victim from replacement candidates
	victim_sector = static_cast<SectorBlk*>(replacementPolicy->getVictim(
	sector_entries));
	}

	// Get the entry of the victim block within the sector
	SectorSubBlk* victim = victim_sector->blks[extractSectorOffset(addr)];

	// Get evicted blocks. Blocks are only evicted if the sectors mismatch and
	// the currently existing sector is valid.
	if ((tag == victim_sector->getTag()) &&
	(is_secure == victim_sector->isSecure())){
	// It would be a hit if victim was valid, and upgrades do not call
	// findVictim, so it cannot happen
	assert(!victim->isValid());
	} else {
	// The whole sector must be evicted to make room for the new sector
	for (const auto& blk : victim_sector->blks){
	evict_blks.push_back(blk);
	}
	}

	return victim;
	}

	int
	SectorTags::extractSectorOffset(Addr addr) const
	{
	return (addr >> sectorShift) & sectorMask;
	}

	Addr
	SectorTags::regenerateBlkAddr(const CacheBlk* blk) const
	{
	const SectorSubBlk* blk_cast = static_cast<const SectorSubBlk*>(blk);
	const SectorBlk* sec_blk = blk_cast->getSectorBlock();
	const Addr sec_addr = indexingPolicy->regenerateAddr(blk->tag, sec_blk);
	return sec_addr \| ((Addr)blk_cast->getSectorOffset() << sectorShift);
	}

	void
	SectorTags::forEachBlk(std::function<void(CacheBlk &)> visitor)
	{
	for (SectorSubBlk& blk : blks) {
	visitor(blk);
	}
	}

	bool
	SectorTags::anyBlk(std::function<bool(CacheBlk &)> visitor)
	{
	for (SectorSubBlk& blk : blks) {
	if (visitor(blk)) {
	return true;
	}
	}
	return false;
	}

	SectorTags *
	SectorTagsParams::create()
	{
	// There must be a indexing policy
	fatal_if(!indexing_policy, "An indexing policy is required");

	return new SectorTags(this);
	}