| /* |
| * Copyright (c) 2012-2014,2017 ARM Limited |
| * All rights reserved. |
| * |
| * The license below extends only to copyright in the software and shall |
| * not be construed as granting a license to any other intellectual |
| * property including but not limited to intellectual property relating |
| * to a hardware implementation of the functionality of the software |
| * licensed hereunder. You may use the software subject to the license |
| * terms below provided that you ensure that this notice is replicated |
| * unmodified and in its entirety in all distributions of the software, |
| * modified or unmodified, in source code or in binary form. |
| * |
| * Copyright (c) 2003-2005,2014 The Regents of The University of Michigan |
| * 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: Erik Hallnor |
| */ |
| |
| /** |
| * @file |
| * Declaration of a base set associative tag store. |
| */ |
| |
| #ifndef __MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__ |
| #define __MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__ |
| |
| #include <functional> |
| #include <string> |
| #include <vector> |
| |
| #include "base/logging.hh" |
| #include "base/types.hh" |
| #include "debug/CacheRepl.hh" |
| #include "mem/cache/base.hh" |
| #include "mem/cache/blk.hh" |
| #include "mem/cache/replacement_policies/base.hh" |
| #include "mem/cache/tags/base.hh" |
| #include "mem/cache/tags/cacheset.hh" |
| #include "mem/packet.hh" |
| #include "params/BaseSetAssoc.hh" |
| |
| /** |
| * A BaseSetAssoc cache tag store. |
| * @sa \ref gem5MemorySystem "gem5 Memory System" |
| * |
| * The BaseSetAssoc placement policy divides the cache into s sets of w |
| * cache lines (ways). A cache line is mapped onto a set, and can be placed |
| * into any of the ways of this set. |
| */ |
| class BaseSetAssoc : public BaseTags |
| { |
| public: |
| /** Typedef the block type used in this tag store. */ |
| typedef CacheBlk BlkType; |
| /** Typedef the set type used in this tag store. */ |
| typedef CacheSet<CacheBlk> SetType; |
| |
| protected: |
| /** The associativity of the cache. */ |
| const unsigned assoc; |
| /** The allocatable associativity of the cache (alloc mask). */ |
| unsigned allocAssoc; |
| |
| /** The cache blocks. */ |
| std::vector<BlkType> blks; |
| |
| /** The number of sets in the cache. */ |
| const unsigned numSets; |
| |
| /** Whether tags and data are accessed sequentially. */ |
| const bool sequentialAccess; |
| |
| /** The cache sets. */ |
| std::vector<SetType> sets; |
| |
| /** The amount to shift the address to get the set. */ |
| int setShift; |
| /** The amount to shift the address to get the tag. */ |
| int tagShift; |
| /** Mask out all bits that aren't part of the set index. */ |
| unsigned setMask; |
| |
| /** Replacement policy */ |
| BaseReplacementPolicy *replacementPolicy; |
| |
| public: |
| /** Convenience typedef. */ |
| typedef BaseSetAssocParams Params; |
| |
| /** |
| * Construct and initialize this tag store. |
| */ |
| BaseSetAssoc(const Params *p); |
| |
| /** |
| * Destructor |
| */ |
| virtual ~BaseSetAssoc() {}; |
| |
| /** |
| * This function updates the tags when a block is invalidated. It also |
| * updates the replacement data. |
| * |
| * @param blk The block to invalidate. |
| */ |
| void invalidate(CacheBlk *blk) override; |
| |
| /** |
| * Access block and update replacement data. May not succeed, in which case |
| * nullptr is returned. This has all the implications of a cache |
| * access and should only be used as such. Returns the access latency as a |
| * side effect. |
| * @param addr The address to find. |
| * @param is_secure True if the target memory space is secure. |
| * @param lat The access latency. |
| * @return Pointer to the cache block if found. |
| */ |
| CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) override |
| { |
| BlkType *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; |
| } |
| |
| if (blk != nullptr) { |
| // If a cache hit |
| lat = accessLatency; |
| // Check if the block to be accessed is available. If not, |
| // apply the accessLatency on top of block->whenReady. |
| if (blk->whenReady > curTick() && |
| cache->ticksToCycles(blk->whenReady - curTick()) > |
| accessLatency) { |
| lat = cache->ticksToCycles(blk->whenReady - curTick()) + |
| accessLatency; |
| } |
| |
| // Update number of references to accessed block |
| blk->refCount++; |
| |
| // Update replacement data of accessed block |
| replacementPolicy->touch(blk->replacementData); |
| } else { |
| // If a cache miss |
| lat = lookupLatency; |
| } |
| |
| return blk; |
| } |
| |
| /** |
| * Finds the given address in the cache, do not update replacement data. |
| * i.e. This is a no-side-effect find of a block. |
| * @param addr The address to find. |
| * @param is_secure True if the target memory space is secure. |
| * @param asid The address space ID. |
| * @return Pointer to the cache block if found. |
| */ |
| CacheBlk* findBlock(Addr addr, bool is_secure) const override; |
| |
| /** |
| * Find a block given set and way. |
| * |
| * @param set The set of the block. |
| * @param way The way of the block. |
| * @return The block. |
| */ |
| ReplaceableEntry* findBlockBySetAndWay(int set, int way) const override; |
| |
| /** |
| * Find replacement victim based on address. The list of evicted blocks |
| * only contains the victim. |
| * |
| * @param addr Address to find a victim for. |
| * @param is_secure True if the target memory space is secure. |
| * @param evict_blks Cache blocks to be evicted. |
| * @return Cache block to be replaced. |
| */ |
| CacheBlk* findVictim(Addr addr, const bool is_secure, |
| std::vector<CacheBlk*>& evict_blks) const override |
| { |
| // Get possible locations for the victim block |
| std::vector<CacheBlk*> locations = getPossibleLocations(addr); |
| |
| // Choose replacement victim from replacement candidates |
| CacheBlk* victim = static_cast<CacheBlk*>(replacementPolicy->getVictim( |
| std::vector<ReplaceableEntry*>( |
| locations.begin(), locations.end()))); |
| |
| // There is only one eviction for this replacement |
| evict_blks.push_back(victim); |
| |
| DPRINTF(CacheRepl, "set %x, way %x: selecting blk for replacement\n", |
| victim->set, victim->way); |
| |
| return victim; |
| } |
| |
| /** |
| * Find all possible block locations for insertion and replacement of |
| * an address. Should be called immediately before ReplacementPolicy's |
| * findVictim() not to break cache resizing. |
| * Returns blocks in all ways belonging to the set of the address. |
| * |
| * @param addr The addr to a find possible locations for. |
| * @return The possible locations. |
| */ |
| const std::vector<CacheBlk*> getPossibleLocations(Addr addr) const |
| { |
| return sets[extractSet(addr)].blks; |
| } |
| |
| /** |
| * Insert the new block into the cache and update replacement data. |
| * |
| * @param pkt Packet holding the address to update |
| * @param blk The block to update. |
| */ |
| void insertBlock(const PacketPtr pkt, CacheBlk *blk) override |
| { |
| // Insert block |
| BaseTags::insertBlock(pkt, blk); |
| |
| // Increment tag counter |
| tagsInUse++; |
| |
| // Update replacement policy |
| replacementPolicy->reset(blk->replacementData); |
| } |
| |
| /** |
| * Limit the allocation for the cache ways. |
| * @param ways The maximum number of ways available for replacement. |
| */ |
| virtual void setWayAllocationMax(int ways) override |
| { |
| fatal_if(ways < 1, "Allocation limit must be greater than zero"); |
| allocAssoc = ways; |
| } |
| |
| /** |
| * Get the way allocation mask limit. |
| * @return The maximum number of ways available for replacement. |
| */ |
| virtual int getWayAllocationMax() const override |
| { |
| return allocAssoc; |
| } |
| |
| /** |
| * Generate the tag from the given address. |
| * @param addr The address to get the tag from. |
| * @return The tag of the address. |
| */ |
| Addr extractTag(Addr addr) const override |
| { |
| return (addr >> tagShift); |
| } |
| |
| /** |
| * Regenerate the block address from the tag and set. |
| * |
| * @param block The block. |
| * @return the block address. |
| */ |
| Addr regenerateBlkAddr(const CacheBlk* blk) const override |
| { |
| return ((blk->tag << tagShift) | ((Addr)blk->set << setShift)); |
| } |
| |
| void forEachBlk(std::function<void(CacheBlk &)> visitor) override { |
| for (CacheBlk& blk : blks) { |
| visitor(blk); |
| } |
| } |
| |
| bool anyBlk(std::function<bool(CacheBlk &)> visitor) override { |
| for (CacheBlk& blk : blks) { |
| if (visitor(blk)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| private: |
| /** |
| * Calculate the set index from the address. |
| * |
| * @param addr The address to get the set from. |
| * @return The set index of the address. |
| */ |
| int extractSet(Addr addr) const |
| { |
| return ((addr >> setShift) & setMask); |
| } |
| }; |
| |
| #endif //__MEM_CACHE_TAGS_BASE_SET_ASSOC_HH__ |