1/*
2 * Copyright (c) 2010-2015 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * Copyright (c) 2010,2015 Advanced Micro Devices, Inc.
16 * All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Authors: Erik Hallnor
42 * Dave Greene
43 * Nathan Binkert
44 * Steve Reinhardt
45 * Ron Dreslinski
46 * Andreas Sandberg
47 */
48
49/**
50 * @file
51 * Cache definitions.
52 */
53
54#include "mem/cache/cache.hh"
55
56#include "base/misc.hh"
57#include "base/types.hh"
58#include "debug/Cache.hh"
59#include "debug/CachePort.hh"
60#include "debug/CacheTags.hh"
61#include "mem/cache/blk.hh"
62#include "mem/cache/mshr.hh"
63#include "mem/cache/prefetch/base.hh"
64#include "sim/sim_exit.hh"
65
66Cache::Cache(const CacheParams *p)
67 : BaseCache(p, p->system->cacheLineSize()),
68 tags(p->tags),
69 prefetcher(p->prefetcher),
70 doFastWrites(true),
71 prefetchOnAccess(p->prefetch_on_access),
72 clusivity(p->clusivity),
73 writebackClean(p->writeback_clean),
74 tempBlockWriteback(nullptr),
75 writebackTempBlockAtomicEvent(this, false,
76 EventBase::Delayed_Writeback_Pri)
77{
78 tempBlock = new CacheBlk();
79 tempBlock->data = new uint8_t[blkSize];
80
81 cpuSidePort = new CpuSidePort(p->name + ".cpu_side", this,
82 "CpuSidePort");
83 memSidePort = new MemSidePort(p->name + ".mem_side", this,
84 "MemSidePort");
85
86 tags->setCache(this);
87 if (prefetcher)
88 prefetcher->setCache(this);
89}
90
91Cache::~Cache()
92{
93 delete [] tempBlock->data;
94 delete tempBlock;
95
96 delete cpuSidePort;
97 delete memSidePort;
98}
99
100void
101Cache::regStats()
102{
103 BaseCache::regStats();
104}
105
106void
107Cache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
108{
109 assert(pkt->isRequest());
110
111 uint64_t overwrite_val;
112 bool overwrite_mem;
113 uint64_t condition_val64;
114 uint32_t condition_val32;
115
116 int offset = tags->extractBlkOffset(pkt->getAddr());
117 uint8_t *blk_data = blk->data + offset;
118
119 assert(sizeof(uint64_t) >= pkt->getSize());
120
121 overwrite_mem = true;
122 // keep a copy of our possible write value, and copy what is at the
123 // memory address into the packet
124 pkt->writeData((uint8_t *)&overwrite_val);
125 pkt->setData(blk_data);
126
127 if (pkt->req->isCondSwap()) {
128 if (pkt->getSize() == sizeof(uint64_t)) {
129 condition_val64 = pkt->req->getExtraData();
130 overwrite_mem = !std::memcmp(&condition_val64, blk_data,
131 sizeof(uint64_t));
132 } else if (pkt->getSize() == sizeof(uint32_t)) {
133 condition_val32 = (uint32_t)pkt->req->getExtraData();
134 overwrite_mem = !std::memcmp(&condition_val32, blk_data,
135 sizeof(uint32_t));
136 } else
137 panic("Invalid size for conditional read/write\n");
138 }
139
140 if (overwrite_mem) {
141 std::memcpy(blk_data, &overwrite_val, pkt->getSize());
142 blk->status |= BlkDirty;
143 }
144}
145
146
147void
148Cache::satisfyCpuSideRequest(PacketPtr pkt, CacheBlk *blk,
149 bool deferred_response, bool pending_downgrade)
150{
151 assert(pkt->isRequest());
152
153 assert(blk && blk->isValid());
154 // Occasionally this is not true... if we are a lower-level cache
155 // satisfying a string of Read and ReadEx requests from
156 // upper-level caches, a Read will mark the block as shared but we
157 // can satisfy a following ReadEx anyway since we can rely on the
158 // Read requester(s) to have buffered the ReadEx snoop and to
159 // invalidate their blocks after receiving them.
160 // assert(!pkt->needsExclusive() || blk->isWritable());
161 assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
162
163 // Check RMW operations first since both isRead() and
164 // isWrite() will be true for them
165 if (pkt->cmd == MemCmd::SwapReq) {
166 cmpAndSwap(blk, pkt);
167 } else if (pkt->isWrite()) {
168 assert(blk->isWritable());
169 // Write or WriteLine at the first cache with block in Exclusive
170 if (blk->checkWrite(pkt)) {
171 pkt->writeDataToBlock(blk->data, blkSize);
172 }
173 // Always mark the line as dirty even if we are a failed
174 // StoreCond so we supply data to any snoops that have
175 // appended themselves to this cache before knowing the store
176 // will fail.
177 blk->status |= BlkDirty;
178 DPRINTF(Cache, "%s for %s addr %#llx size %d (write)\n", __func__,
179 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
180 } else if (pkt->isRead()) {
181 if (pkt->isLLSC()) {
182 blk->trackLoadLocked(pkt);
183 }
184 pkt->setDataFromBlock(blk->data, blkSize);
185 // determine if this read is from a (coherent) cache, or not
186 // by looking at the command type; we could potentially add a
187 // packet attribute such as 'FromCache' to make this check a
188 // bit cleaner
189 if (pkt->cmd == MemCmd::ReadExReq ||
190 pkt->cmd == MemCmd::ReadSharedReq ||
191 pkt->cmd == MemCmd::ReadCleanReq ||
192 pkt->cmd == MemCmd::SCUpgradeFailReq) {
193 assert(pkt->getSize() == blkSize);
194 // special handling for coherent block requests from
195 // upper-level caches
196 if (pkt->needsExclusive()) {
197 // sanity check
198 assert(pkt->cmd == MemCmd::ReadExReq ||
199 pkt->cmd == MemCmd::SCUpgradeFailReq);
200
201 // if we have a dirty copy, make sure the recipient
202 // keeps it marked dirty
203 if (blk->isDirty()) {
204 pkt->assertMemInhibit();
205 }
206 // on ReadExReq we give up our copy unconditionally,
207 // even if this cache is mostly inclusive, we may want
208 // to revisit this
209 invalidateBlock(blk);
210 } else if (blk->isWritable() && !pending_downgrade &&
211 !pkt->sharedAsserted() &&
212 pkt->cmd != MemCmd::ReadCleanReq) {
213 // we can give the requester an exclusive copy (by not
214 // asserting shared line) on a read request if:
215 // - we have an exclusive copy at this level (& below)
216 // - we don't have a pending snoop from below
217 // signaling another read request
218 // - no other cache above has a copy (otherwise it
219 // would have asseretd shared line on request)
220 // - we are not satisfying an instruction fetch (this
221 // prevents dirty data in the i-cache)
222
223 if (blk->isDirty()) {
224 // special considerations if we're owner:
225 if (!deferred_response) {
226 // if we are responding immediately and can
227 // signal that we're transferring ownership
228 // (inhibit set) along with exclusivity
229 // (shared not set), do so
230 pkt->assertMemInhibit();
231
232 // if this cache is mostly inclusive, we keep
233 // the block as writable (exclusive), and pass
234 // it upwards as writable and dirty
235 // (modified), hence we have multiple caches
236 // considering the same block writable,
237 // something that we get away with due to the
238 // fact that: 1) this cache has been
239 // considered the ordering points and
240 // responded to all snoops up till now, and 2)
241 // we always snoop upwards before consulting
242 // the local cache, both on a normal request
243 // (snooping done by the crossbar), and on a
244 // snoop
245 blk->status &= ~BlkDirty;
246
247 // if this cache is mostly exclusive with
248 // respect to the cache above, drop the block
249 if (clusivity == Enums::mostly_excl) {
250 invalidateBlock(blk);
251 }
252 } else {
253 // if we're responding after our own miss,
254 // there's a window where the recipient didn't
255 // know it was getting ownership and may not
256 // have responded to snoops correctly, so we
257 // can't pass off ownership *or* exclusivity
258 pkt->assertShared();
259 }
260 }
261 } else {
262 // otherwise only respond with a shared copy
263 pkt->assertShared();
264 }
265 }
266 } else {
267 // Upgrade or Invalidate, since we have it Exclusively (E or
268 // M), we ack then invalidate.
269 assert(pkt->isUpgrade() || pkt->isInvalidate());
270
271 // for invalidations we could be looking at the temp block
272 // (for upgrades we always allocate)
273 invalidateBlock(blk);
274 DPRINTF(Cache, "%s for %s addr %#llx size %d (invalidation)\n",
275 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
276 }
277}
278
279
280/////////////////////////////////////////////////////
281//
282// MSHR helper functions
283//
284/////////////////////////////////////////////////////
285
286
287void
288Cache::markInService(MSHR *mshr, bool pending_dirty_resp)
289{
290 markInServiceInternal(mshr, pending_dirty_resp);
291}
292
293/////////////////////////////////////////////////////
294//
295// Access path: requests coming in from the CPU side
296//
297/////////////////////////////////////////////////////
298
299bool
300Cache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
301 PacketList &writebacks)
302{
303 // sanity check
304 assert(pkt->isRequest());
305
306 chatty_assert(!(isReadOnly && pkt->isWrite()),
307 "Should never see a write in a read-only cache %s\n",
308 name());
309
310 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
311 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
312
313 if (pkt->req->isUncacheable()) {
314 DPRINTF(Cache, "%s%s addr %#llx uncacheable\n", pkt->cmdString(),
315 pkt->req->isInstFetch() ? " (ifetch)" : "",
316 pkt->getAddr());
317
318 // flush and invalidate any existing block
319 CacheBlk *old_blk(tags->findBlock(pkt->getAddr(), pkt->isSecure()));
320 if (old_blk && old_blk->isValid()) {
321 if (old_blk->isDirty() || writebackClean)
322 writebacks.push_back(writebackBlk(old_blk));
323 else
324 writebacks.push_back(cleanEvictBlk(old_blk));
325 tags->invalidate(old_blk);
326 old_blk->invalidate();
327 }
328
329 blk = NULL;
330 // lookupLatency is the latency in case the request is uncacheable.
331 lat = lookupLatency;
332 return false;
333 }
334
335 ContextID id = pkt->req->hasContextId() ?
336 pkt->req->contextId() : InvalidContextID;
337 // Here lat is the value passed as parameter to accessBlock() function
338 // that can modify its value.
339 blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), lat, id);
340
341 DPRINTF(Cache, "%s%s addr %#llx size %d (%s) %s\n", pkt->cmdString(),
342 pkt->req->isInstFetch() ? " (ifetch)" : "",
343 pkt->getAddr(), pkt->getSize(), pkt->isSecure() ? "s" : "ns",
344 blk ? "hit " + blk->print() : "miss");
345
346
347 if (pkt->isEviction()) {
348 // We check for presence of block in above caches before issuing
349 // Writeback or CleanEvict to write buffer. Therefore the only
350 // possible cases can be of a CleanEvict packet coming from above
351 // encountering a Writeback generated in this cache peer cache and
352 // waiting in the write buffer. Cases of upper level peer caches
353 // generating CleanEvict and Writeback or simply CleanEvict and
354 // CleanEvict almost simultaneously will be caught by snoops sent out
355 // by crossbar.
356 std::vector<MSHR *> outgoing;
357 if (writeBuffer.findMatches(pkt->getAddr(), pkt->isSecure(),
358 outgoing)) {
359 assert(outgoing.size() == 1);
360 MSHR *wb_entry = outgoing[0];
361 assert(wb_entry->getNumTargets() == 1);
362 PacketPtr wbPkt = wb_entry->getTarget()->pkt;
363 assert(wbPkt->isWriteback());
364
365 if (pkt->isCleanEviction()) {
366 // The CleanEvict and WritebackClean snoops into other
367 // peer caches of the same level while traversing the
368 // crossbar. If a copy of the block is found, the
369 // packet is deleted in the crossbar. Hence, none of
370 // the other upper level caches connected to this
371 // cache have the block, so we can clear the
372 // BLOCK_CACHED flag in the Writeback if set and
373 // discard the CleanEvict by returning true.
374 wbPkt->clearBlockCached();
375 return true;
376 } else {
377 assert(pkt->cmd == MemCmd::WritebackDirty);
378 // Dirty writeback from above trumps our clean
379 // writeback... discard here
380 // Note: markInService will remove entry from writeback buffer.
381 markInService(wb_entry, false);
382 delete wbPkt;
383 }
384 }
385 }
386
387 // Writeback handling is special case. We can write the block into
388 // the cache without having a writeable copy (or any copy at all).
389 if (pkt->isWriteback()) {
390 assert(blkSize == pkt->getSize());
391
392 // we could get a clean writeback while we are having
393 // outstanding accesses to a block, do the simple thing for
394 // now and drop the clean writeback so that we do not upset
395 // any ordering/decisions about ownership already taken
396 if (pkt->cmd == MemCmd::WritebackClean &&
397 mshrQueue.findMatch(pkt->getAddr(), pkt->isSecure())) {
398 DPRINTF(Cache, "Clean writeback %#llx to block with MSHR, "
399 "dropping\n", pkt->getAddr());
400 return true;
401 }
402
403 if (blk == NULL) {
404 // need to do a replacement
405 blk = allocateBlock(pkt->getAddr(), pkt->isSecure(), writebacks);
406 if (blk == NULL) {
407 // no replaceable block available: give up, fwd to next level.
408 incMissCount(pkt);
409 return false;
410 }
411 tags->insertBlock(pkt, blk);
412
413 blk->status = (BlkValid | BlkReadable);
414 if (pkt->isSecure()) {
415 blk->status |= BlkSecure;
416 }
417 }
418 // only mark the block dirty if we got a writeback command,
419 // and leave it as is for a clean writeback
420 if (pkt->cmd == MemCmd::WritebackDirty) {
421 blk->status |= BlkDirty;
422 }
423 // if shared is not asserted we got the writeback in modified
424 // state, if it is asserted we are in the owned state
425 if (!pkt->sharedAsserted()) {
426 blk->status |= BlkWritable;
427 }
428 // nothing else to do; writeback doesn't expect response
429 assert(!pkt->needsResponse());
430 std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
431 DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
432 incHitCount(pkt);
433 return true;
434 } else if (pkt->cmd == MemCmd::CleanEvict) {
435 if (blk != NULL) {
436 // Found the block in the tags, need to stop CleanEvict from
437 // propagating further down the hierarchy. Returning true will
438 // treat the CleanEvict like a satisfied write request and delete
439 // it.
440 return true;
441 }
442 // We didn't find the block here, propagate the CleanEvict further
443 // down the memory hierarchy. Returning false will treat the CleanEvict
444 // like a Writeback which could not find a replaceable block so has to
445 // go to next level.
446 return false;
447 } else if ((blk != NULL) &&
448 (pkt->needsExclusive() ? blk->isWritable()
449 : blk->isReadable())) {
450 // OK to satisfy access
451 incHitCount(pkt);
452 satisfyCpuSideRequest(pkt, blk);
453 return true;
454 }
455
456 // Can't satisfy access normally... either no block (blk == NULL)
457 // or have block but need exclusive & only have shared.
458
459 incMissCount(pkt);
460
461 if (blk == NULL && pkt->isLLSC() && pkt->isWrite()) {
462 // complete miss on store conditional... just give up now
463 pkt->req->setExtraData(0);
464 return true;
465 }
466
467 return false;
468}
469
| 1/*
2 * Copyright (c) 2010-2015 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2002-2005 The Regents of The University of Michigan
15 * Copyright (c) 2010,2015 Advanced Micro Devices, Inc.
16 * All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Authors: Erik Hallnor
42 * Dave Greene
43 * Nathan Binkert
44 * Steve Reinhardt
45 * Ron Dreslinski
46 * Andreas Sandberg
47 */
48
49/**
50 * @file
51 * Cache definitions.
52 */
53
54#include "mem/cache/cache.hh"
55
56#include "base/misc.hh"
57#include "base/types.hh"
58#include "debug/Cache.hh"
59#include "debug/CachePort.hh"
60#include "debug/CacheTags.hh"
61#include "mem/cache/blk.hh"
62#include "mem/cache/mshr.hh"
63#include "mem/cache/prefetch/base.hh"
64#include "sim/sim_exit.hh"
65
66Cache::Cache(const CacheParams *p)
67 : BaseCache(p, p->system->cacheLineSize()),
68 tags(p->tags),
69 prefetcher(p->prefetcher),
70 doFastWrites(true),
71 prefetchOnAccess(p->prefetch_on_access),
72 clusivity(p->clusivity),
73 writebackClean(p->writeback_clean),
74 tempBlockWriteback(nullptr),
75 writebackTempBlockAtomicEvent(this, false,
76 EventBase::Delayed_Writeback_Pri)
77{
78 tempBlock = new CacheBlk();
79 tempBlock->data = new uint8_t[blkSize];
80
81 cpuSidePort = new CpuSidePort(p->name + ".cpu_side", this,
82 "CpuSidePort");
83 memSidePort = new MemSidePort(p->name + ".mem_side", this,
84 "MemSidePort");
85
86 tags->setCache(this);
87 if (prefetcher)
88 prefetcher->setCache(this);
89}
90
91Cache::~Cache()
92{
93 delete [] tempBlock->data;
94 delete tempBlock;
95
96 delete cpuSidePort;
97 delete memSidePort;
98}
99
100void
101Cache::regStats()
102{
103 BaseCache::regStats();
104}
105
106void
107Cache::cmpAndSwap(CacheBlk *blk, PacketPtr pkt)
108{
109 assert(pkt->isRequest());
110
111 uint64_t overwrite_val;
112 bool overwrite_mem;
113 uint64_t condition_val64;
114 uint32_t condition_val32;
115
116 int offset = tags->extractBlkOffset(pkt->getAddr());
117 uint8_t *blk_data = blk->data + offset;
118
119 assert(sizeof(uint64_t) >= pkt->getSize());
120
121 overwrite_mem = true;
122 // keep a copy of our possible write value, and copy what is at the
123 // memory address into the packet
124 pkt->writeData((uint8_t *)&overwrite_val);
125 pkt->setData(blk_data);
126
127 if (pkt->req->isCondSwap()) {
128 if (pkt->getSize() == sizeof(uint64_t)) {
129 condition_val64 = pkt->req->getExtraData();
130 overwrite_mem = !std::memcmp(&condition_val64, blk_data,
131 sizeof(uint64_t));
132 } else if (pkt->getSize() == sizeof(uint32_t)) {
133 condition_val32 = (uint32_t)pkt->req->getExtraData();
134 overwrite_mem = !std::memcmp(&condition_val32, blk_data,
135 sizeof(uint32_t));
136 } else
137 panic("Invalid size for conditional read/write\n");
138 }
139
140 if (overwrite_mem) {
141 std::memcpy(blk_data, &overwrite_val, pkt->getSize());
142 blk->status |= BlkDirty;
143 }
144}
145
146
147void
148Cache::satisfyCpuSideRequest(PacketPtr pkt, CacheBlk *blk,
149 bool deferred_response, bool pending_downgrade)
150{
151 assert(pkt->isRequest());
152
153 assert(blk && blk->isValid());
154 // Occasionally this is not true... if we are a lower-level cache
155 // satisfying a string of Read and ReadEx requests from
156 // upper-level caches, a Read will mark the block as shared but we
157 // can satisfy a following ReadEx anyway since we can rely on the
158 // Read requester(s) to have buffered the ReadEx snoop and to
159 // invalidate their blocks after receiving them.
160 // assert(!pkt->needsExclusive() || blk->isWritable());
161 assert(pkt->getOffset(blkSize) + pkt->getSize() <= blkSize);
162
163 // Check RMW operations first since both isRead() and
164 // isWrite() will be true for them
165 if (pkt->cmd == MemCmd::SwapReq) {
166 cmpAndSwap(blk, pkt);
167 } else if (pkt->isWrite()) {
168 assert(blk->isWritable());
169 // Write or WriteLine at the first cache with block in Exclusive
170 if (blk->checkWrite(pkt)) {
171 pkt->writeDataToBlock(blk->data, blkSize);
172 }
173 // Always mark the line as dirty even if we are a failed
174 // StoreCond so we supply data to any snoops that have
175 // appended themselves to this cache before knowing the store
176 // will fail.
177 blk->status |= BlkDirty;
178 DPRINTF(Cache, "%s for %s addr %#llx size %d (write)\n", __func__,
179 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
180 } else if (pkt->isRead()) {
181 if (pkt->isLLSC()) {
182 blk->trackLoadLocked(pkt);
183 }
184 pkt->setDataFromBlock(blk->data, blkSize);
185 // determine if this read is from a (coherent) cache, or not
186 // by looking at the command type; we could potentially add a
187 // packet attribute such as 'FromCache' to make this check a
188 // bit cleaner
189 if (pkt->cmd == MemCmd::ReadExReq ||
190 pkt->cmd == MemCmd::ReadSharedReq ||
191 pkt->cmd == MemCmd::ReadCleanReq ||
192 pkt->cmd == MemCmd::SCUpgradeFailReq) {
193 assert(pkt->getSize() == blkSize);
194 // special handling for coherent block requests from
195 // upper-level caches
196 if (pkt->needsExclusive()) {
197 // sanity check
198 assert(pkt->cmd == MemCmd::ReadExReq ||
199 pkt->cmd == MemCmd::SCUpgradeFailReq);
200
201 // if we have a dirty copy, make sure the recipient
202 // keeps it marked dirty
203 if (blk->isDirty()) {
204 pkt->assertMemInhibit();
205 }
206 // on ReadExReq we give up our copy unconditionally,
207 // even if this cache is mostly inclusive, we may want
208 // to revisit this
209 invalidateBlock(blk);
210 } else if (blk->isWritable() && !pending_downgrade &&
211 !pkt->sharedAsserted() &&
212 pkt->cmd != MemCmd::ReadCleanReq) {
213 // we can give the requester an exclusive copy (by not
214 // asserting shared line) on a read request if:
215 // - we have an exclusive copy at this level (& below)
216 // - we don't have a pending snoop from below
217 // signaling another read request
218 // - no other cache above has a copy (otherwise it
219 // would have asseretd shared line on request)
220 // - we are not satisfying an instruction fetch (this
221 // prevents dirty data in the i-cache)
222
223 if (blk->isDirty()) {
224 // special considerations if we're owner:
225 if (!deferred_response) {
226 // if we are responding immediately and can
227 // signal that we're transferring ownership
228 // (inhibit set) along with exclusivity
229 // (shared not set), do so
230 pkt->assertMemInhibit();
231
232 // if this cache is mostly inclusive, we keep
233 // the block as writable (exclusive), and pass
234 // it upwards as writable and dirty
235 // (modified), hence we have multiple caches
236 // considering the same block writable,
237 // something that we get away with due to the
238 // fact that: 1) this cache has been
239 // considered the ordering points and
240 // responded to all snoops up till now, and 2)
241 // we always snoop upwards before consulting
242 // the local cache, both on a normal request
243 // (snooping done by the crossbar), and on a
244 // snoop
245 blk->status &= ~BlkDirty;
246
247 // if this cache is mostly exclusive with
248 // respect to the cache above, drop the block
249 if (clusivity == Enums::mostly_excl) {
250 invalidateBlock(blk);
251 }
252 } else {
253 // if we're responding after our own miss,
254 // there's a window where the recipient didn't
255 // know it was getting ownership and may not
256 // have responded to snoops correctly, so we
257 // can't pass off ownership *or* exclusivity
258 pkt->assertShared();
259 }
260 }
261 } else {
262 // otherwise only respond with a shared copy
263 pkt->assertShared();
264 }
265 }
266 } else {
267 // Upgrade or Invalidate, since we have it Exclusively (E or
268 // M), we ack then invalidate.
269 assert(pkt->isUpgrade() || pkt->isInvalidate());
270
271 // for invalidations we could be looking at the temp block
272 // (for upgrades we always allocate)
273 invalidateBlock(blk);
274 DPRINTF(Cache, "%s for %s addr %#llx size %d (invalidation)\n",
275 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
276 }
277}
278
279
280/////////////////////////////////////////////////////
281//
282// MSHR helper functions
283//
284/////////////////////////////////////////////////////
285
286
287void
288Cache::markInService(MSHR *mshr, bool pending_dirty_resp)
289{
290 markInServiceInternal(mshr, pending_dirty_resp);
291}
292
293/////////////////////////////////////////////////////
294//
295// Access path: requests coming in from the CPU side
296//
297/////////////////////////////////////////////////////
298
299bool
300Cache::access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
301 PacketList &writebacks)
302{
303 // sanity check
304 assert(pkt->isRequest());
305
306 chatty_assert(!(isReadOnly && pkt->isWrite()),
307 "Should never see a write in a read-only cache %s\n",
308 name());
309
310 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
311 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
312
313 if (pkt->req->isUncacheable()) {
314 DPRINTF(Cache, "%s%s addr %#llx uncacheable\n", pkt->cmdString(),
315 pkt->req->isInstFetch() ? " (ifetch)" : "",
316 pkt->getAddr());
317
318 // flush and invalidate any existing block
319 CacheBlk *old_blk(tags->findBlock(pkt->getAddr(), pkt->isSecure()));
320 if (old_blk && old_blk->isValid()) {
321 if (old_blk->isDirty() || writebackClean)
322 writebacks.push_back(writebackBlk(old_blk));
323 else
324 writebacks.push_back(cleanEvictBlk(old_blk));
325 tags->invalidate(old_blk);
326 old_blk->invalidate();
327 }
328
329 blk = NULL;
330 // lookupLatency is the latency in case the request is uncacheable.
331 lat = lookupLatency;
332 return false;
333 }
334
335 ContextID id = pkt->req->hasContextId() ?
336 pkt->req->contextId() : InvalidContextID;
337 // Here lat is the value passed as parameter to accessBlock() function
338 // that can modify its value.
339 blk = tags->accessBlock(pkt->getAddr(), pkt->isSecure(), lat, id);
340
341 DPRINTF(Cache, "%s%s addr %#llx size %d (%s) %s\n", pkt->cmdString(),
342 pkt->req->isInstFetch() ? " (ifetch)" : "",
343 pkt->getAddr(), pkt->getSize(), pkt->isSecure() ? "s" : "ns",
344 blk ? "hit " + blk->print() : "miss");
345
346
347 if (pkt->isEviction()) {
348 // We check for presence of block in above caches before issuing
349 // Writeback or CleanEvict to write buffer. Therefore the only
350 // possible cases can be of a CleanEvict packet coming from above
351 // encountering a Writeback generated in this cache peer cache and
352 // waiting in the write buffer. Cases of upper level peer caches
353 // generating CleanEvict and Writeback or simply CleanEvict and
354 // CleanEvict almost simultaneously will be caught by snoops sent out
355 // by crossbar.
356 std::vector<MSHR *> outgoing;
357 if (writeBuffer.findMatches(pkt->getAddr(), pkt->isSecure(),
358 outgoing)) {
359 assert(outgoing.size() == 1);
360 MSHR *wb_entry = outgoing[0];
361 assert(wb_entry->getNumTargets() == 1);
362 PacketPtr wbPkt = wb_entry->getTarget()->pkt;
363 assert(wbPkt->isWriteback());
364
365 if (pkt->isCleanEviction()) {
366 // The CleanEvict and WritebackClean snoops into other
367 // peer caches of the same level while traversing the
368 // crossbar. If a copy of the block is found, the
369 // packet is deleted in the crossbar. Hence, none of
370 // the other upper level caches connected to this
371 // cache have the block, so we can clear the
372 // BLOCK_CACHED flag in the Writeback if set and
373 // discard the CleanEvict by returning true.
374 wbPkt->clearBlockCached();
375 return true;
376 } else {
377 assert(pkt->cmd == MemCmd::WritebackDirty);
378 // Dirty writeback from above trumps our clean
379 // writeback... discard here
380 // Note: markInService will remove entry from writeback buffer.
381 markInService(wb_entry, false);
382 delete wbPkt;
383 }
384 }
385 }
386
387 // Writeback handling is special case. We can write the block into
388 // the cache without having a writeable copy (or any copy at all).
389 if (pkt->isWriteback()) {
390 assert(blkSize == pkt->getSize());
391
392 // we could get a clean writeback while we are having
393 // outstanding accesses to a block, do the simple thing for
394 // now and drop the clean writeback so that we do not upset
395 // any ordering/decisions about ownership already taken
396 if (pkt->cmd == MemCmd::WritebackClean &&
397 mshrQueue.findMatch(pkt->getAddr(), pkt->isSecure())) {
398 DPRINTF(Cache, "Clean writeback %#llx to block with MSHR, "
399 "dropping\n", pkt->getAddr());
400 return true;
401 }
402
403 if (blk == NULL) {
404 // need to do a replacement
405 blk = allocateBlock(pkt->getAddr(), pkt->isSecure(), writebacks);
406 if (blk == NULL) {
407 // no replaceable block available: give up, fwd to next level.
408 incMissCount(pkt);
409 return false;
410 }
411 tags->insertBlock(pkt, blk);
412
413 blk->status = (BlkValid | BlkReadable);
414 if (pkt->isSecure()) {
415 blk->status |= BlkSecure;
416 }
417 }
418 // only mark the block dirty if we got a writeback command,
419 // and leave it as is for a clean writeback
420 if (pkt->cmd == MemCmd::WritebackDirty) {
421 blk->status |= BlkDirty;
422 }
423 // if shared is not asserted we got the writeback in modified
424 // state, if it is asserted we are in the owned state
425 if (!pkt->sharedAsserted()) {
426 blk->status |= BlkWritable;
427 }
428 // nothing else to do; writeback doesn't expect response
429 assert(!pkt->needsResponse());
430 std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
431 DPRINTF(Cache, "%s new state is %s\n", __func__, blk->print());
432 incHitCount(pkt);
433 return true;
434 } else if (pkt->cmd == MemCmd::CleanEvict) {
435 if (blk != NULL) {
436 // Found the block in the tags, need to stop CleanEvict from
437 // propagating further down the hierarchy. Returning true will
438 // treat the CleanEvict like a satisfied write request and delete
439 // it.
440 return true;
441 }
442 // We didn't find the block here, propagate the CleanEvict further
443 // down the memory hierarchy. Returning false will treat the CleanEvict
444 // like a Writeback which could not find a replaceable block so has to
445 // go to next level.
446 return false;
447 } else if ((blk != NULL) &&
448 (pkt->needsExclusive() ? blk->isWritable()
449 : blk->isReadable())) {
450 // OK to satisfy access
451 incHitCount(pkt);
452 satisfyCpuSideRequest(pkt, blk);
453 return true;
454 }
455
456 // Can't satisfy access normally... either no block (blk == NULL)
457 // or have block but need exclusive & only have shared.
458
459 incMissCount(pkt);
460
461 if (blk == NULL && pkt->isLLSC() && pkt->isWrite()) {
462 // complete miss on store conditional... just give up now
463 pkt->req->setExtraData(0);
464 return true;
465 }
466
467 return false;
468}
469
|
470
471class ForwardResponseRecord : public Packet::SenderState
472{
473 public:
474
475 ForwardResponseRecord() {}
476};
477
| |
478void
479Cache::doWritebacks(PacketList& writebacks, Tick forward_time)
480{
481 while (!writebacks.empty()) {
482 PacketPtr wbPkt = writebacks.front();
483 // We use forwardLatency here because we are copying writebacks to
484 // write buffer. Call isCachedAbove for both Writebacks and
485 // CleanEvicts. If isCachedAbove returns true we set BLOCK_CACHED flag
486 // in Writebacks and discard CleanEvicts.
487 if (isCachedAbove(wbPkt)) {
488 if (wbPkt->cmd == MemCmd::CleanEvict) {
489 // Delete CleanEvict because cached copies exist above. The
490 // packet destructor will delete the request object because
491 // this is a non-snoop request packet which does not require a
492 // response.
493 delete wbPkt;
494 } else if (wbPkt->cmd == MemCmd::WritebackClean) {
495 // clean writeback, do not send since the block is
496 // still cached above
497 assert(writebackClean);
498 delete wbPkt;
499 } else {
500 assert(wbPkt->cmd == MemCmd::WritebackDirty);
501 // Set BLOCK_CACHED flag in Writeback and send below, so that
502 // the Writeback does not reset the bit corresponding to this
503 // address in the snoop filter below.
504 wbPkt->setBlockCached();
505 allocateWriteBuffer(wbPkt, forward_time);
506 }
507 } else {
508 // If the block is not cached above, send packet below. Both
509 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
510 // reset the bit corresponding to this address in the snoop filter
511 // below.
512 allocateWriteBuffer(wbPkt, forward_time);
513 }
514 writebacks.pop_front();
515 }
516}
517
518void
519Cache::doWritebacksAtomic(PacketList& writebacks)
520{
521 while (!writebacks.empty()) {
522 PacketPtr wbPkt = writebacks.front();
523 // Call isCachedAbove for both Writebacks and CleanEvicts. If
524 // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks
525 // and discard CleanEvicts.
526 if (isCachedAbove(wbPkt, false)) {
527 if (wbPkt->cmd == MemCmd::WritebackDirty) {
528 // Set BLOCK_CACHED flag in Writeback and send below,
529 // so that the Writeback does not reset the bit
530 // corresponding to this address in the snoop filter
531 // below. We can discard CleanEvicts because cached
532 // copies exist above. Atomic mode isCachedAbove
533 // modifies packet to set BLOCK_CACHED flag
534 memSidePort->sendAtomic(wbPkt);
535 }
536 } else {
537 // If the block is not cached above, send packet below. Both
538 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
539 // reset the bit corresponding to this address in the snoop filter
540 // below.
541 memSidePort->sendAtomic(wbPkt);
542 }
543 writebacks.pop_front();
544 // In case of CleanEvicts, the packet destructor will delete the
545 // request object because this is a non-snoop request packet which
546 // does not require a response.
547 delete wbPkt;
548 }
549}
550
551
552void
553Cache::recvTimingSnoopResp(PacketPtr pkt)
554{
555 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
556 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
557
558 assert(pkt->isResponse());
| 470void
471Cache::doWritebacks(PacketList& writebacks, Tick forward_time)
472{
473 while (!writebacks.empty()) {
474 PacketPtr wbPkt = writebacks.front();
475 // We use forwardLatency here because we are copying writebacks to
476 // write buffer. Call isCachedAbove for both Writebacks and
477 // CleanEvicts. If isCachedAbove returns true we set BLOCK_CACHED flag
478 // in Writebacks and discard CleanEvicts.
479 if (isCachedAbove(wbPkt)) {
480 if (wbPkt->cmd == MemCmd::CleanEvict) {
481 // Delete CleanEvict because cached copies exist above. The
482 // packet destructor will delete the request object because
483 // this is a non-snoop request packet which does not require a
484 // response.
485 delete wbPkt;
486 } else if (wbPkt->cmd == MemCmd::WritebackClean) {
487 // clean writeback, do not send since the block is
488 // still cached above
489 assert(writebackClean);
490 delete wbPkt;
491 } else {
492 assert(wbPkt->cmd == MemCmd::WritebackDirty);
493 // Set BLOCK_CACHED flag in Writeback and send below, so that
494 // the Writeback does not reset the bit corresponding to this
495 // address in the snoop filter below.
496 wbPkt->setBlockCached();
497 allocateWriteBuffer(wbPkt, forward_time);
498 }
499 } else {
500 // If the block is not cached above, send packet below. Both
501 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
502 // reset the bit corresponding to this address in the snoop filter
503 // below.
504 allocateWriteBuffer(wbPkt, forward_time);
505 }
506 writebacks.pop_front();
507 }
508}
509
510void
511Cache::doWritebacksAtomic(PacketList& writebacks)
512{
513 while (!writebacks.empty()) {
514 PacketPtr wbPkt = writebacks.front();
515 // Call isCachedAbove for both Writebacks and CleanEvicts. If
516 // isCachedAbove returns true we set BLOCK_CACHED flag in Writebacks
517 // and discard CleanEvicts.
518 if (isCachedAbove(wbPkt, false)) {
519 if (wbPkt->cmd == MemCmd::WritebackDirty) {
520 // Set BLOCK_CACHED flag in Writeback and send below,
521 // so that the Writeback does not reset the bit
522 // corresponding to this address in the snoop filter
523 // below. We can discard CleanEvicts because cached
524 // copies exist above. Atomic mode isCachedAbove
525 // modifies packet to set BLOCK_CACHED flag
526 memSidePort->sendAtomic(wbPkt);
527 }
528 } else {
529 // If the block is not cached above, send packet below. Both
530 // CleanEvict and Writeback with BLOCK_CACHED flag cleared will
531 // reset the bit corresponding to this address in the snoop filter
532 // below.
533 memSidePort->sendAtomic(wbPkt);
534 }
535 writebacks.pop_front();
536 // In case of CleanEvicts, the packet destructor will delete the
537 // request object because this is a non-snoop request packet which
538 // does not require a response.
539 delete wbPkt;
540 }
541}
542
543
544void
545Cache::recvTimingSnoopResp(PacketPtr pkt)
546{
547 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
548 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
549
550 assert(pkt->isResponse());
|
559
560 // must be cache-to-cache response from upper to lower level
561 ForwardResponseRecord *rec =
562 dynamic_cast<ForwardResponseRecord *>(pkt->senderState);
| |
563 assert(!system->bypassCaches());
564
| 551 assert(!system->bypassCaches());
552
|
565 if (rec == NULL) {
566 // @todo What guarantee do we have that this HardPFResp is
567 // actually for this cache, and not a cache closer to the
568 // memory?
| 553 // determine if the response is from a snoop request we created
554 // (in which case it should be in the outstandingSnoop), or if we
555 // merely forwarded someone else's snoop request
556 const bool forwardAsSnoop = outstandingSnoop.find(pkt->req) ==
557 outstandingSnoop.end();
558
559 if (!forwardAsSnoop) {
560 // the packet came from this cache, so sink it here and do not
561 // forward it
|
569 assert(pkt->cmd == MemCmd::HardPFResp);
| 562 assert(pkt->cmd == MemCmd::HardPFResp);
|
570 // Check if it's a prefetch response and handle it. We shouldn't
571 // get any other kinds of responses without FRRs.
572 DPRINTF(Cache, "Got prefetch response from above for addr %#llx (%s)\n",
573 pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
| 563
564 outstandingSnoop.erase(pkt->req);
565
566 DPRINTF(Cache, "Got prefetch response from above for addr "
567 "%#llx (%s)\n", pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
|
574 recvTimingResp(pkt);
575 return;
576 }
577
| 568 recvTimingResp(pkt);
569 return;
570 }
571
|
578 pkt->popSenderState();
579 delete rec;
| |
580 // forwardLatency is set here because there is a response from an
581 // upper level cache.
582 // To pay the delay that occurs if the packet comes from the bus,
583 // we charge also headerDelay.
584 Tick snoop_resp_time = clockEdge(forwardLatency) + pkt->headerDelay;
585 // Reset the timing of the packet.
586 pkt->headerDelay = pkt->payloadDelay = 0;
587 memSidePort->schedTimingSnoopResp(pkt, snoop_resp_time);
588}
589
590void
591Cache::promoteWholeLineWrites(PacketPtr pkt)
592{
593 // Cache line clearing instructions
594 if (doFastWrites && (pkt->cmd == MemCmd::WriteReq) &&
595 (pkt->getSize() == blkSize) && (pkt->getOffset(blkSize) == 0)) {
596 pkt->cmd = MemCmd::WriteLineReq;
597 DPRINTF(Cache, "packet promoted from Write to WriteLineReq\n");
598 }
599}
600
601bool
602Cache::recvTimingReq(PacketPtr pkt)
603{
604 DPRINTF(CacheTags, "%s tags: %s\n", __func__, tags->print());
605
606 assert(pkt->isRequest());
607
608 // Just forward the packet if caches are disabled.
609 if (system->bypassCaches()) {
610 // @todo This should really enqueue the packet rather
611 bool M5_VAR_USED success = memSidePort->sendTimingReq(pkt);
612 assert(success);
613 return true;
614 }
615
616 promoteWholeLineWrites(pkt);
617
618 if (pkt->memInhibitAsserted()) {
619 // a cache above us (but not where the packet came from) is
620 // responding to the request
621 DPRINTF(Cache, "mem inhibited on addr %#llx (%s): not responding\n",
622 pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
623
624 // if the packet needs exclusive, and the cache that has
625 // promised to respond (setting the inhibit flag) is not
626 // providing exclusive (it is in O vs M state), we know that
627 // there may be other shared copies in the system; go out and
628 // invalidate them all
629 if (pkt->needsExclusive() && !pkt->isSupplyExclusive()) {
630 // create a downstream express snoop with cleared packet
631 // flags, there is no need to allocate any data as the
632 // packet is merely used to co-ordinate state transitions
633 Packet *snoop_pkt = new Packet(pkt, true, false);
634
635 // also reset the bus time that the original packet has
636 // not yet paid for
637 snoop_pkt->headerDelay = snoop_pkt->payloadDelay = 0;
638
639 // make this an instantaneous express snoop, and let the
640 // other caches in the system know that the packet is
641 // inhibited, because we have found the authorative copy
642 // (O) that will supply the right data
643 snoop_pkt->setExpressSnoop();
644 snoop_pkt->assertMemInhibit();
645
646 // this express snoop travels towards the memory, and at
647 // every crossbar it is snooped upwards thus reaching
648 // every cache in the system
649 bool M5_VAR_USED success = memSidePort->sendTimingReq(snoop_pkt);
650 // express snoops always succeed
651 assert(success);
652
653 // main memory will delete the packet
654 }
655
656 // queue for deletion, as the sending cache is still relying
657 // on the packet
658 pendingDelete.reset(pkt);
659
660 // no need to take any action in this particular cache as the
661 // caches along the path to memory are allowed to keep lines
662 // in a shared state, and a cache above us already committed
663 // to responding
664 return true;
665 }
666
667 // anything that is merely forwarded pays for the forward latency and
668 // the delay provided by the crossbar
669 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
670
671 // We use lookupLatency here because it is used to specify the latency
672 // to access.
673 Cycles lat = lookupLatency;
674 CacheBlk *blk = NULL;
675 bool satisfied = false;
676 {
677 PacketList writebacks;
678 // Note that lat is passed by reference here. The function
679 // access() calls accessBlock() which can modify lat value.
680 satisfied = access(pkt, blk, lat, writebacks);
681
682 // copy writebacks to write buffer here to ensure they logically
683 // proceed anything happening below
684 doWritebacks(writebacks, forward_time);
685 }
686
687 // Here we charge the headerDelay that takes into account the latencies
688 // of the bus, if the packet comes from it.
689 // The latency charged it is just lat that is the value of lookupLatency
690 // modified by access() function, or if not just lookupLatency.
691 // In case of a hit we are neglecting response latency.
692 // In case of a miss we are neglecting forward latency.
693 Tick request_time = clockEdge(lat) + pkt->headerDelay;
694 // Here we reset the timing of the packet.
695 pkt->headerDelay = pkt->payloadDelay = 0;
696
697 // track time of availability of next prefetch, if any
698 Tick next_pf_time = MaxTick;
699
700 bool needsResponse = pkt->needsResponse();
701
702 if (satisfied) {
703 // should never be satisfying an uncacheable access as we
704 // flush and invalidate any existing block as part of the
705 // lookup
706 assert(!pkt->req->isUncacheable());
707
708 // hit (for all other request types)
709
710 if (prefetcher && (prefetchOnAccess || (blk && blk->wasPrefetched()))) {
711 if (blk)
712 blk->status &= ~BlkHWPrefetched;
713
714 // Don't notify on SWPrefetch
715 if (!pkt->cmd.isSWPrefetch())
716 next_pf_time = prefetcher->notify(pkt);
717 }
718
719 if (needsResponse) {
720 pkt->makeTimingResponse();
721 // @todo: Make someone pay for this
722 pkt->headerDelay = pkt->payloadDelay = 0;
723
724 // In this case we are considering request_time that takes
725 // into account the delay of the xbar, if any, and just
726 // lat, neglecting responseLatency, modelling hit latency
727 // just as lookupLatency or or the value of lat overriden
728 // by access(), that calls accessBlock() function.
729 cpuSidePort->schedTimingResp(pkt, request_time, true);
730 } else {
731 DPRINTF(Cache, "%s satisfied %s addr %#llx, no response needed\n",
732 __func__, pkt->cmdString(), pkt->getAddr(),
733 pkt->getSize());
734
735 // queue the packet for deletion, as the sending cache is
736 // still relying on it; if the block is found in access(),
737 // CleanEvict and Writeback messages will be deleted
738 // here as well
739 pendingDelete.reset(pkt);
740 }
741 } else {
742 // miss
743
744 Addr blk_addr = blockAlign(pkt->getAddr());
745
746 // ignore any existing MSHR if we are dealing with an
747 // uncacheable request
748 MSHR *mshr = pkt->req->isUncacheable() ? nullptr :
749 mshrQueue.findMatch(blk_addr, pkt->isSecure());
750
751 // Software prefetch handling:
752 // To keep the core from waiting on data it won't look at
753 // anyway, send back a response with dummy data. Miss handling
754 // will continue asynchronously. Unfortunately, the core will
755 // insist upon freeing original Packet/Request, so we have to
756 // create a new pair with a different lifecycle. Note that this
757 // processing happens before any MSHR munging on the behalf of
758 // this request because this new Request will be the one stored
759 // into the MSHRs, not the original.
760 if (pkt->cmd.isSWPrefetch()) {
761 assert(needsResponse);
762 assert(pkt->req->hasPaddr());
763 assert(!pkt->req->isUncacheable());
764
765 // There's no reason to add a prefetch as an additional target
766 // to an existing MSHR. If an outstanding request is already
767 // in progress, there is nothing for the prefetch to do.
768 // If this is the case, we don't even create a request at all.
769 PacketPtr pf = nullptr;
770
771 if (!mshr) {
772 // copy the request and create a new SoftPFReq packet
773 RequestPtr req = new Request(pkt->req->getPaddr(),
774 pkt->req->getSize(),
775 pkt->req->getFlags(),
776 pkt->req->masterId());
777 pf = new Packet(req, pkt->cmd);
778 pf->allocate();
779 assert(pf->getAddr() == pkt->getAddr());
780 assert(pf->getSize() == pkt->getSize());
781 }
782
783 pkt->makeTimingResponse();
784 // for debugging, set all the bits in the response data
785 // (also keeps valgrind from complaining when debugging settings
786 // print out instruction results)
787 std::memset(pkt->getPtr<uint8_t>(), 0xFF, pkt->getSize());
788 // request_time is used here, taking into account lat and the delay
789 // charged if the packet comes from the xbar.
790 cpuSidePort->schedTimingResp(pkt, request_time, true);
791
792 // If an outstanding request is in progress (we found an
793 // MSHR) this is set to null
794 pkt = pf;
795 }
796
797 if (mshr) {
798 /// MSHR hit
799 /// @note writebacks will be checked in getNextMSHR()
800 /// for any conflicting requests to the same block
801
802 //@todo remove hw_pf here
803
804 // Coalesce unless it was a software prefetch (see above).
805 if (pkt) {
806 assert(!pkt->isWriteback());
807 // CleanEvicts corresponding to blocks which have
808 // outstanding requests in MSHRs are simply sunk here
809 if (pkt->cmd == MemCmd::CleanEvict) {
810 pendingDelete.reset(pkt);
811 } else {
812 DPRINTF(Cache, "%s coalescing MSHR for %s addr %#llx size %d\n",
813 __func__, pkt->cmdString(), pkt->getAddr(),
814 pkt->getSize());
815
816 assert(pkt->req->masterId() < system->maxMasters());
817 mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
818 if (mshr->threadNum != 0/*pkt->req->threadId()*/) {
819 mshr->threadNum = -1;
820 }
821 // We use forward_time here because it is the same
822 // considering new targets. We have multiple
823 // requests for the same address here. It
824 // specifies the latency to allocate an internal
825 // buffer and to schedule an event to the queued
826 // port and also takes into account the additional
827 // delay of the xbar.
828 mshr->allocateTarget(pkt, forward_time, order++,
829 allocOnFill(pkt->cmd));
830 if (mshr->getNumTargets() == numTarget) {
831 noTargetMSHR = mshr;
832 setBlocked(Blocked_NoTargets);
833 // need to be careful with this... if this mshr isn't
834 // ready yet (i.e. time > curTick()), we don't want to
835 // move it ahead of mshrs that are ready
836 // mshrQueue.moveToFront(mshr);
837 }
838 }
839 // We should call the prefetcher reguardless if the request is
840 // satisfied or not, reguardless if the request is in the MSHR or
841 // not. The request could be a ReadReq hit, but still not
842 // satisfied (potentially because of a prior write to the same
843 // cache line. So, even when not satisfied, tehre is an MSHR
844 // already allocated for this, we need to let the prefetcher know
845 // about the request
846 if (prefetcher) {
847 // Don't notify on SWPrefetch
848 if (!pkt->cmd.isSWPrefetch())
849 next_pf_time = prefetcher->notify(pkt);
850 }
851 }
852 } else {
853 // no MSHR
854 assert(pkt->req->masterId() < system->maxMasters());
855 if (pkt->req->isUncacheable()) {
856 mshr_uncacheable[pkt->cmdToIndex()][pkt->req->masterId()]++;
857 } else {
858 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
859 }
860
861 if (pkt->isEviction() ||
862 (pkt->req->isUncacheable() && pkt->isWrite())) {
863 // We use forward_time here because there is an
864 // uncached memory write, forwarded to WriteBuffer.
865 allocateWriteBuffer(pkt, forward_time);
866 } else {
867 if (blk && blk->isValid()) {
868 // should have flushed and have no valid block
869 assert(!pkt->req->isUncacheable());
870
871 // If we have a write miss to a valid block, we
872 // need to mark the block non-readable. Otherwise
873 // if we allow reads while there's an outstanding
874 // write miss, the read could return stale data
875 // out of the cache block... a more aggressive
876 // system could detect the overlap (if any) and
877 // forward data out of the MSHRs, but we don't do
878 // that yet. Note that we do need to leave the
879 // block valid so that it stays in the cache, in
880 // case we get an upgrade response (and hence no
881 // new data) when the write miss completes.
882 // As long as CPUs do proper store/load forwarding
883 // internally, and have a sufficiently weak memory
884 // model, this is probably unnecessary, but at some
885 // point it must have seemed like we needed it...
886 assert(pkt->needsExclusive());
887 assert(!blk->isWritable());
888 blk->status &= ~BlkReadable;
889 }
890 // Here we are using forward_time, modelling the latency of
891 // a miss (outbound) just as forwardLatency, neglecting the
892 // lookupLatency component.
893 allocateMissBuffer(pkt, forward_time);
894 }
895
896 if (prefetcher) {
897 // Don't notify on SWPrefetch
898 if (!pkt->cmd.isSWPrefetch())
899 next_pf_time = prefetcher->notify(pkt);
900 }
901 }
902 }
903
904 if (next_pf_time != MaxTick)
905 schedMemSideSendEvent(next_pf_time);
906
907 return true;
908}
909
910
911// See comment in cache.hh.
912PacketPtr
913Cache::getBusPacket(PacketPtr cpu_pkt, CacheBlk *blk,
914 bool needsExclusive) const
915{
916 bool blkValid = blk && blk->isValid();
917
918 if (cpu_pkt->req->isUncacheable()) {
919 // note that at the point we see the uncacheable request we
920 // flush any block, but there could be an outstanding MSHR,
921 // and the cache could have filled again before we actually
922 // send out the forwarded uncacheable request (blk could thus
923 // be non-null)
924 return NULL;
925 }
926
927 if (!blkValid &&
928 (cpu_pkt->isUpgrade() ||
929 cpu_pkt->isEviction())) {
930 // Writebacks that weren't allocated in access() and upgrades
931 // from upper-level caches that missed completely just go
932 // through.
933 return NULL;
934 }
935
936 assert(cpu_pkt->needsResponse());
937
938 MemCmd cmd;
939 // @TODO make useUpgrades a parameter.
940 // Note that ownership protocols require upgrade, otherwise a
941 // write miss on a shared owned block will generate a ReadExcl,
942 // which will clobber the owned copy.
943 const bool useUpgrades = true;
944 if (blkValid && useUpgrades) {
945 // only reason to be here is that blk is shared
946 // (read-only) and we need exclusive
947 assert(needsExclusive);
948 assert(!blk->isWritable());
949 cmd = cpu_pkt->isLLSC() ? MemCmd::SCUpgradeReq : MemCmd::UpgradeReq;
950 } else if (cpu_pkt->cmd == MemCmd::SCUpgradeFailReq ||
951 cpu_pkt->cmd == MemCmd::StoreCondFailReq) {
952 // Even though this SC will fail, we still need to send out the
953 // request and get the data to supply it to other snoopers in the case
954 // where the determination the StoreCond fails is delayed due to
955 // all caches not being on the same local bus.
956 cmd = MemCmd::SCUpgradeFailReq;
957 } else if (cpu_pkt->cmd == MemCmd::WriteLineReq) {
958 // forward as invalidate to all other caches, this gives us
959 // the line in exclusive state, and invalidates all other
960 // copies
961 cmd = MemCmd::InvalidateReq;
962 } else {
963 // block is invalid
964 cmd = needsExclusive ? MemCmd::ReadExReq :
965 (isReadOnly ? MemCmd::ReadCleanReq : MemCmd::ReadSharedReq);
966 }
967 PacketPtr pkt = new Packet(cpu_pkt->req, cmd, blkSize);
968
969 // if there are sharers in the upper levels, pass that info downstream
970 if (cpu_pkt->sharedAsserted()) {
971 // note that cpu_pkt may have spent a considerable time in the
972 // MSHR queue and that the information could possibly be out
973 // of date, however, there is no harm in conservatively
974 // assuming the block is shared
975 pkt->assertShared();
976 DPRINTF(Cache, "%s passing shared from %s to %s addr %#llx size %d\n",
977 __func__, cpu_pkt->cmdString(), pkt->cmdString(),
978 pkt->getAddr(), pkt->getSize());
979 }
980
981 // the packet should be block aligned
982 assert(pkt->getAddr() == blockAlign(pkt->getAddr()));
983
984 pkt->allocate();
985 DPRINTF(Cache, "%s created %s from %s for addr %#llx size %d\n",
986 __func__, pkt->cmdString(), cpu_pkt->cmdString(), pkt->getAddr(),
987 pkt->getSize());
988 return pkt;
989}
990
991
992Tick
993Cache::recvAtomic(PacketPtr pkt)
994{
995 // We are in atomic mode so we pay just for lookupLatency here.
996 Cycles lat = lookupLatency;
997 // @TODO: make this a parameter
998 bool last_level_cache = false;
999
1000 // Forward the request if the system is in cache bypass mode.
1001 if (system->bypassCaches())
1002 return ticksToCycles(memSidePort->sendAtomic(pkt));
1003
1004 promoteWholeLineWrites(pkt);
1005
1006 if (pkt->memInhibitAsserted()) {
1007 // have to invalidate ourselves and any lower caches even if
1008 // upper cache will be responding
1009 if (pkt->isInvalidate()) {
1010 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
1011 if (blk && blk->isValid()) {
1012 tags->invalidate(blk);
1013 blk->invalidate();
1014 DPRINTF(Cache, "rcvd mem-inhibited %s on %#llx (%s):"
1015 " invalidating\n",
1016 pkt->cmdString(), pkt->getAddr(),
1017 pkt->isSecure() ? "s" : "ns");
1018 }
1019 if (!last_level_cache) {
1020 DPRINTF(Cache, "forwarding mem-inhibited %s on %#llx (%s)\n",
1021 pkt->cmdString(), pkt->getAddr(),
1022 pkt->isSecure() ? "s" : "ns");
1023 lat += ticksToCycles(memSidePort->sendAtomic(pkt));
1024 }
1025 } else {
1026 DPRINTF(Cache, "rcvd mem-inhibited %s on %#llx: not responding\n",
1027 pkt->cmdString(), pkt->getAddr());
1028 }
1029
1030 return lat * clockPeriod();
1031 }
1032
1033 // should assert here that there are no outstanding MSHRs or
1034 // writebacks... that would mean that someone used an atomic
1035 // access in timing mode
1036
1037 CacheBlk *blk = NULL;
1038 PacketList writebacks;
1039 bool satisfied = access(pkt, blk, lat, writebacks);
1040
1041 // handle writebacks resulting from the access here to ensure they
1042 // logically proceed anything happening below
1043 doWritebacksAtomic(writebacks);
1044
1045 if (!satisfied) {
1046 // MISS
1047
1048 PacketPtr bus_pkt = getBusPacket(pkt, blk, pkt->needsExclusive());
1049
1050 bool is_forward = (bus_pkt == NULL);
1051
1052 if (is_forward) {
1053 // just forwarding the same request to the next level
1054 // no local cache operation involved
1055 bus_pkt = pkt;
1056 }
1057
1058 DPRINTF(Cache, "Sending an atomic %s for %#llx (%s)\n",
1059 bus_pkt->cmdString(), bus_pkt->getAddr(),
1060 bus_pkt->isSecure() ? "s" : "ns");
1061
1062#if TRACING_ON
1063 CacheBlk::State old_state = blk ? blk->status : 0;
1064#endif
1065
1066 lat += ticksToCycles(memSidePort->sendAtomic(bus_pkt));
1067
1068 // We are now dealing with the response handling
1069 DPRINTF(Cache, "Receive response: %s for addr %#llx (%s) in state %i\n",
1070 bus_pkt->cmdString(), bus_pkt->getAddr(),
1071 bus_pkt->isSecure() ? "s" : "ns",
1072 old_state);
1073
1074 // If packet was a forward, the response (if any) is already
1075 // in place in the bus_pkt == pkt structure, so we don't need
1076 // to do anything. Otherwise, use the separate bus_pkt to
1077 // generate response to pkt and then delete it.
1078 if (!is_forward) {
1079 if (pkt->needsResponse()) {
1080 assert(bus_pkt->isResponse());
1081 if (bus_pkt->isError()) {
1082 pkt->makeAtomicResponse();
1083 pkt->copyError(bus_pkt);
1084 } else if (pkt->cmd == MemCmd::InvalidateReq) {
1085 if (blk) {
1086 // invalidate response to a cache that received
1087 // an invalidate request
1088 satisfyCpuSideRequest(pkt, blk);
1089 }
1090 } else if (pkt->cmd == MemCmd::WriteLineReq) {
1091 // note the use of pkt, not bus_pkt here.
1092
1093 // write-line request to the cache that promoted
1094 // the write to a whole line
1095 blk = handleFill(pkt, blk, writebacks,
1096 allocOnFill(pkt->cmd));
1097 satisfyCpuSideRequest(pkt, blk);
1098 } else if (bus_pkt->isRead() ||
1099 bus_pkt->cmd == MemCmd::UpgradeResp) {
1100 // we're updating cache state to allow us to
1101 // satisfy the upstream request from the cache
1102 blk = handleFill(bus_pkt, blk, writebacks,
1103 allocOnFill(pkt->cmd));
1104 satisfyCpuSideRequest(pkt, blk);
1105 } else {
1106 // we're satisfying the upstream request without
1107 // modifying cache state, e.g., a write-through
1108 pkt->makeAtomicResponse();
1109 }
1110 }
1111 delete bus_pkt;
1112 }
1113 }
1114
1115 // Note that we don't invoke the prefetcher at all in atomic mode.
1116 // It's not clear how to do it properly, particularly for
1117 // prefetchers that aggressively generate prefetch candidates and
1118 // rely on bandwidth contention to throttle them; these will tend
1119 // to pollute the cache in atomic mode since there is no bandwidth
1120 // contention. If we ever do want to enable prefetching in atomic
1121 // mode, though, this is the place to do it... see timingAccess()
1122 // for an example (though we'd want to issue the prefetch(es)
1123 // immediately rather than calling requestMemSideBus() as we do
1124 // there).
1125
1126 // do any writebacks resulting from the response handling
1127 doWritebacksAtomic(writebacks);
1128
1129 // if we used temp block, check to see if its valid and if so
1130 // clear it out, but only do so after the call to recvAtomic is
1131 // finished so that any downstream observers (such as a snoop
1132 // filter), first see the fill, and only then see the eviction
1133 if (blk == tempBlock && tempBlock->isValid()) {
1134 // the atomic CPU calls recvAtomic for fetch and load/store
1135 // sequentuially, and we may already have a tempBlock
1136 // writeback from the fetch that we have not yet sent
1137 if (tempBlockWriteback) {
1138 // if that is the case, write the prevoius one back, and
1139 // do not schedule any new event
1140 writebackTempBlockAtomic();
1141 } else {
1142 // the writeback/clean eviction happens after the call to
1143 // recvAtomic has finished (but before any successive
1144 // calls), so that the response handling from the fill is
1145 // allowed to happen first
1146 schedule(writebackTempBlockAtomicEvent, curTick());
1147 }
1148
1149 tempBlockWriteback = (blk->isDirty() || writebackClean) ?
1150 writebackBlk(blk) : cleanEvictBlk(blk);
1151 blk->invalidate();
1152 }
1153
1154 if (pkt->needsResponse()) {
1155 pkt->makeAtomicResponse();
1156 }
1157
1158 return lat * clockPeriod();
1159}
1160
1161
1162void
1163Cache::functionalAccess(PacketPtr pkt, bool fromCpuSide)
1164{
1165 if (system->bypassCaches()) {
1166 // Packets from the memory side are snoop request and
1167 // shouldn't happen in bypass mode.
1168 assert(fromCpuSide);
1169
1170 // The cache should be flushed if we are in cache bypass mode,
1171 // so we don't need to check if we need to update anything.
1172 memSidePort->sendFunctional(pkt);
1173 return;
1174 }
1175
1176 Addr blk_addr = blockAlign(pkt->getAddr());
1177 bool is_secure = pkt->isSecure();
1178 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
1179 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
1180
1181 pkt->pushLabel(name());
1182
1183 CacheBlkPrintWrapper cbpw(blk);
1184
1185 // Note that just because an L2/L3 has valid data doesn't mean an
1186 // L1 doesn't have a more up-to-date modified copy that still
1187 // needs to be found. As a result we always update the request if
1188 // we have it, but only declare it satisfied if we are the owner.
1189
1190 // see if we have data at all (owned or otherwise)
1191 bool have_data = blk && blk->isValid()
1192 && pkt->checkFunctional(&cbpw, blk_addr, is_secure, blkSize,
1193 blk->data);
1194
1195 // data we have is dirty if marked as such or if valid & ownership
1196 // pending due to outstanding UpgradeReq
1197 bool have_dirty =
1198 have_data && (blk->isDirty() ||
1199 (mshr && mshr->inService && mshr->isPendingDirty()));
1200
1201 bool done = have_dirty
1202 || cpuSidePort->checkFunctional(pkt)
1203 || mshrQueue.checkFunctional(pkt, blk_addr)
1204 || writeBuffer.checkFunctional(pkt, blk_addr)
1205 || memSidePort->checkFunctional(pkt);
1206
1207 DPRINTF(Cache, "functional %s %#llx (%s) %s%s%s\n",
1208 pkt->cmdString(), pkt->getAddr(), is_secure ? "s" : "ns",
1209 (blk && blk->isValid()) ? "valid " : "",
1210 have_data ? "data " : "", done ? "done " : "");
1211
1212 // We're leaving the cache, so pop cache->name() label
1213 pkt->popLabel();
1214
1215 if (done) {
1216 pkt->makeResponse();
1217 } else {
1218 // if it came as a request from the CPU side then make sure it
1219 // continues towards the memory side
1220 if (fromCpuSide) {
1221 memSidePort->sendFunctional(pkt);
1222 } else if (forwardSnoops && cpuSidePort->isSnooping()) {
1223 // if it came from the memory side, it must be a snoop request
1224 // and we should only forward it if we are forwarding snoops
1225 cpuSidePort->sendFunctionalSnoop(pkt);
1226 }
1227 }
1228}
1229
1230
1231/////////////////////////////////////////////////////
1232//
1233// Response handling: responses from the memory side
1234//
1235/////////////////////////////////////////////////////
1236
1237
1238void
1239Cache::recvTimingResp(PacketPtr pkt)
1240{
1241 assert(pkt->isResponse());
1242
1243 // all header delay should be paid for by the crossbar, unless
1244 // this is a prefetch response from above
1245 panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
1246 "%s saw a non-zero packet delay\n", name());
1247
1248 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
1249 bool is_error = pkt->isError();
1250
1251 assert(mshr);
1252
1253 if (is_error) {
1254 DPRINTF(Cache, "Cache received packet with error for addr %#llx (%s), "
1255 "cmd: %s\n", pkt->getAddr(), pkt->isSecure() ? "s" : "ns",
1256 pkt->cmdString());
1257 }
1258
1259 DPRINTF(Cache, "Handling response %s for addr %#llx size %d (%s)\n",
1260 pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
1261 pkt->isSecure() ? "s" : "ns");
1262
1263 MSHRQueue *mq = mshr->queue;
1264 bool wasFull = mq->isFull();
1265
1266 if (mshr == noTargetMSHR) {
1267 // we always clear at least one target
1268 clearBlocked(Blocked_NoTargets);
1269 noTargetMSHR = NULL;
1270 }
1271
1272 // Initial target is used just for stats
1273 MSHR::Target *initial_tgt = mshr->getTarget();
1274 int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
1275 Tick miss_latency = curTick() - initial_tgt->recvTime;
1276 PacketList writebacks;
1277 // We need forward_time here because we have a call of
1278 // allocateWriteBuffer() that need this parameter to specify the
1279 // time to request the bus. In this case we use forward latency
1280 // because there is a writeback. We pay also here for headerDelay
1281 // that is charged of bus latencies if the packet comes from the
1282 // bus.
1283 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
1284
1285 if (pkt->req->isUncacheable()) {
1286 assert(pkt->req->masterId() < system->maxMasters());
1287 mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
1288 miss_latency;
1289 } else {
1290 assert(pkt->req->masterId() < system->maxMasters());
1291 mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
1292 miss_latency;
1293 }
1294
1295 // upgrade deferred targets if we got exclusive
1296 if (!pkt->sharedAsserted()) {
1297 mshr->promoteExclusive();
1298 }
1299
1300 bool is_fill = !mshr->isForward &&
1301 (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
1302
1303 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
1304
1305 if (is_fill && !is_error) {
1306 DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
1307 pkt->getAddr());
1308
1309 blk = handleFill(pkt, blk, writebacks, mshr->allocOnFill);
1310 assert(blk != NULL);
1311 }
1312
1313 // allow invalidation responses originating from write-line
1314 // requests to be discarded
1315 bool is_invalidate = pkt->isInvalidate();
1316
1317 // First offset for critical word first calculations
1318 int initial_offset = initial_tgt->pkt->getOffset(blkSize);
1319
1320 while (mshr->hasTargets()) {
1321 MSHR::Target *target = mshr->getTarget();
1322 Packet *tgt_pkt = target->pkt;
1323
1324 switch (target->source) {
1325 case MSHR::Target::FromCPU:
1326 Tick completion_time;
1327 // Here we charge on completion_time the delay of the xbar if the
1328 // packet comes from it, charged on headerDelay.
1329 completion_time = pkt->headerDelay;
1330
1331 // Software prefetch handling for cache closest to core
1332 if (tgt_pkt->cmd.isSWPrefetch()) {
1333 // a software prefetch would have already been ack'd immediately
1334 // with dummy data so the core would be able to retire it.
1335 // this request completes right here, so we deallocate it.
1336 delete tgt_pkt->req;
1337 delete tgt_pkt;
1338 break; // skip response
1339 }
1340
1341 // unlike the other packet flows, where data is found in other
1342 // caches or memory and brought back, write-line requests always
1343 // have the data right away, so the above check for "is fill?"
1344 // cannot actually be determined until examining the stored MSHR
1345 // state. We "catch up" with that logic here, which is duplicated
1346 // from above.
1347 if (tgt_pkt->cmd == MemCmd::WriteLineReq) {
1348 assert(!is_error);
1349 // we got the block in exclusive state, so promote any
1350 // deferred targets if possible
1351 mshr->promoteExclusive();
1352 // NB: we use the original packet here and not the response!
1353 blk = handleFill(tgt_pkt, blk, writebacks, mshr->allocOnFill);
1354 assert(blk != NULL);
1355
1356 // treat as a fill, and discard the invalidation
1357 // response
1358 is_fill = true;
1359 is_invalidate = false;
1360 }
1361
1362 if (is_fill) {
1363 satisfyCpuSideRequest(tgt_pkt, blk,
1364 true, mshr->hasPostDowngrade());
1365
1366 // How many bytes past the first request is this one
1367 int transfer_offset =
1368 tgt_pkt->getOffset(blkSize) - initial_offset;
1369 if (transfer_offset < 0) {
1370 transfer_offset += blkSize;
1371 }
1372
1373 // If not critical word (offset) return payloadDelay.
1374 // responseLatency is the latency of the return path
1375 // from lower level caches/memory to an upper level cache or
1376 // the core.
1377 completion_time += clockEdge(responseLatency) +
1378 (transfer_offset ? pkt->payloadDelay : 0);
1379
1380 assert(!tgt_pkt->req->isUncacheable());
1381
1382 assert(tgt_pkt->req->masterId() < system->maxMasters());
1383 missLatency[tgt_pkt->cmdToIndex()][tgt_pkt->req->masterId()] +=
1384 completion_time - target->recvTime;
1385 } else if (pkt->cmd == MemCmd::UpgradeFailResp) {
1386 // failed StoreCond upgrade
1387 assert(tgt_pkt->cmd == MemCmd::StoreCondReq ||
1388 tgt_pkt->cmd == MemCmd::StoreCondFailReq ||
1389 tgt_pkt->cmd == MemCmd::SCUpgradeFailReq);
1390 // responseLatency is the latency of the return path
1391 // from lower level caches/memory to an upper level cache or
1392 // the core.
1393 completion_time += clockEdge(responseLatency) +
1394 pkt->payloadDelay;
1395 tgt_pkt->req->setExtraData(0);
1396 } else {
1397 // not a cache fill, just forwarding response
1398 // responseLatency is the latency of the return path
1399 // from lower level cahces/memory to the core.
1400 completion_time += clockEdge(responseLatency) +
1401 pkt->payloadDelay;
1402 if (pkt->isRead() && !is_error) {
1403 // sanity check
1404 assert(pkt->getAddr() == tgt_pkt->getAddr());
1405 assert(pkt->getSize() >= tgt_pkt->getSize());
1406
1407 tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
1408 }
1409 }
1410 tgt_pkt->makeTimingResponse();
1411 // if this packet is an error copy that to the new packet
1412 if (is_error)
1413 tgt_pkt->copyError(pkt);
1414 if (tgt_pkt->cmd == MemCmd::ReadResp &&
1415 (is_invalidate || mshr->hasPostInvalidate())) {
1416 // If intermediate cache got ReadRespWithInvalidate,
1417 // propagate that. Response should not have
1418 // isInvalidate() set otherwise.
1419 tgt_pkt->cmd = MemCmd::ReadRespWithInvalidate;
1420 DPRINTF(Cache, "%s updated cmd to %s for addr %#llx\n",
1421 __func__, tgt_pkt->cmdString(), tgt_pkt->getAddr());
1422 }
1423 // Reset the bus additional time as it is now accounted for
1424 tgt_pkt->headerDelay = tgt_pkt->payloadDelay = 0;
1425 cpuSidePort->schedTimingResp(tgt_pkt, completion_time, true);
1426 break;
1427
1428 case MSHR::Target::FromPrefetcher:
1429 assert(tgt_pkt->cmd == MemCmd::HardPFReq);
1430 if (blk)
1431 blk->status |= BlkHWPrefetched;
1432 delete tgt_pkt->req;
1433 delete tgt_pkt;
1434 break;
1435
1436 case MSHR::Target::FromSnoop:
1437 // I don't believe that a snoop can be in an error state
1438 assert(!is_error);
1439 // response to snoop request
1440 DPRINTF(Cache, "processing deferred snoop...\n");
1441 assert(!(is_invalidate && !mshr->hasPostInvalidate()));
1442 handleSnoop(tgt_pkt, blk, true, true, mshr->hasPostInvalidate());
1443 break;
1444
1445 default:
1446 panic("Illegal target->source enum %d\n", target->source);
1447 }
1448
1449 mshr->popTarget();
1450 }
1451
1452 if (blk && blk->isValid()) {
1453 // an invalidate response stemming from a write line request
1454 // should not invalidate the block, so check if the
1455 // invalidation should be discarded
1456 if (is_invalidate || mshr->hasPostInvalidate()) {
1457 invalidateBlock(blk);
1458 } else if (mshr->hasPostDowngrade()) {
1459 blk->status &= ~BlkWritable;
1460 }
1461 }
1462
1463 if (mshr->promoteDeferredTargets()) {
1464 // avoid later read getting stale data while write miss is
1465 // outstanding.. see comment in timingAccess()
1466 if (blk) {
1467 blk->status &= ~BlkReadable;
1468 }
1469 mq = mshr->queue;
1470 mq->markPending(mshr);
1471 schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
1472 } else {
1473 mq->deallocate(mshr);
1474 if (wasFull && !mq->isFull()) {
1475 clearBlocked((BlockedCause)mq->index);
1476 }
1477
1478 // Request the bus for a prefetch if this deallocation freed enough
1479 // MSHRs for a prefetch to take place
1480 if (prefetcher && mq == &mshrQueue && mshrQueue.canPrefetch()) {
1481 Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
1482 clockEdge());
1483 if (next_pf_time != MaxTick)
1484 schedMemSideSendEvent(next_pf_time);
1485 }
1486 }
1487 // reset the xbar additional timinig as it is now accounted for
1488 pkt->headerDelay = pkt->payloadDelay = 0;
1489
1490 // copy writebacks to write buffer
1491 doWritebacks(writebacks, forward_time);
1492
1493 // if we used temp block, check to see if its valid and then clear it out
1494 if (blk == tempBlock && tempBlock->isValid()) {
1495 // We use forwardLatency here because we are copying
1496 // Writebacks/CleanEvicts to write buffer. It specifies the latency to
1497 // allocate an internal buffer and to schedule an event to the
1498 // queued port.
1499 if (blk->isDirty() || writebackClean) {
1500 PacketPtr wbPkt = writebackBlk(blk);
1501 allocateWriteBuffer(wbPkt, forward_time);
1502 // Set BLOCK_CACHED flag if cached above.
1503 if (isCachedAbove(wbPkt))
1504 wbPkt->setBlockCached();
1505 } else {
1506 PacketPtr wcPkt = cleanEvictBlk(blk);
1507 // Check to see if block is cached above. If not allocate
1508 // write buffer
1509 if (isCachedAbove(wcPkt))
1510 delete wcPkt;
1511 else
1512 allocateWriteBuffer(wcPkt, forward_time);
1513 }
1514 blk->invalidate();
1515 }
1516
1517 DPRINTF(Cache, "Leaving %s with %s for addr %#llx\n", __func__,
1518 pkt->cmdString(), pkt->getAddr());
1519 delete pkt;
1520}
1521
1522PacketPtr
1523Cache::writebackBlk(CacheBlk *blk)
1524{
1525 chatty_assert(!isReadOnly || writebackClean,
1526 "Writeback from read-only cache");
1527 assert(blk && blk->isValid() && (blk->isDirty() || writebackClean));
1528
1529 writebacks[Request::wbMasterId]++;
1530
1531 Request *req = new Request(tags->regenerateBlkAddr(blk->tag, blk->set),
1532 blkSize, 0, Request::wbMasterId);
1533 if (blk->isSecure())
1534 req->setFlags(Request::SECURE);
1535
1536 req->taskId(blk->task_id);
1537 blk->task_id= ContextSwitchTaskId::Unknown;
1538 blk->tickInserted = curTick();
1539
1540 PacketPtr pkt =
1541 new Packet(req, blk->isDirty() ?
1542 MemCmd::WritebackDirty : MemCmd::WritebackClean);
1543
1544 DPRINTF(Cache, "Create Writeback %#llx writable: %d, dirty: %d\n",
1545 pkt->getAddr(), blk->isWritable(), blk->isDirty());
1546
1547 if (blk->isWritable()) {
1548 // not asserting shared means we pass the block in modified
1549 // state, mark our own block non-writeable
1550 blk->status &= ~BlkWritable;
1551 } else {
1552 // we are in the owned state, tell the receiver
1553 pkt->assertShared();
1554 }
1555
1556 // make sure the block is not marked dirty
1557 blk->status &= ~BlkDirty;
1558
1559 pkt->allocate();
1560 std::memcpy(pkt->getPtr<uint8_t>(), blk->data, blkSize);
1561
1562 return pkt;
1563}
1564
1565PacketPtr
1566Cache::cleanEvictBlk(CacheBlk *blk)
1567{
1568 assert(!writebackClean);
1569 assert(blk && blk->isValid() && !blk->isDirty());
1570 // Creating a zero sized write, a message to the snoop filter
1571 Request *req =
1572 new Request(tags->regenerateBlkAddr(blk->tag, blk->set), blkSize, 0,
1573 Request::wbMasterId);
1574 if (blk->isSecure())
1575 req->setFlags(Request::SECURE);
1576
1577 req->taskId(blk->task_id);
1578 blk->task_id = ContextSwitchTaskId::Unknown;
1579 blk->tickInserted = curTick();
1580
1581 PacketPtr pkt = new Packet(req, MemCmd::CleanEvict);
1582 pkt->allocate();
1583 DPRINTF(Cache, "%s%s %x Create CleanEvict\n", pkt->cmdString(),
1584 pkt->req->isInstFetch() ? " (ifetch)" : "",
1585 pkt->getAddr());
1586
1587 return pkt;
1588}
1589
1590void
1591Cache::memWriteback()
1592{
1593 CacheBlkVisitorWrapper visitor(*this, &Cache::writebackVisitor);
1594 tags->forEachBlk(visitor);
1595}
1596
1597void
1598Cache::memInvalidate()
1599{
1600 CacheBlkVisitorWrapper visitor(*this, &Cache::invalidateVisitor);
1601 tags->forEachBlk(visitor);
1602}
1603
1604bool
1605Cache::isDirty() const
1606{
1607 CacheBlkIsDirtyVisitor visitor;
1608 tags->forEachBlk(visitor);
1609
1610 return visitor.isDirty();
1611}
1612
1613bool
1614Cache::writebackVisitor(CacheBlk &blk)
1615{
1616 if (blk.isDirty()) {
1617 assert(blk.isValid());
1618
1619 Request request(tags->regenerateBlkAddr(blk.tag, blk.set),
1620 blkSize, 0, Request::funcMasterId);
1621 request.taskId(blk.task_id);
1622
1623 Packet packet(&request, MemCmd::WriteReq);
1624 packet.dataStatic(blk.data);
1625
1626 memSidePort->sendFunctional(&packet);
1627
1628 blk.status &= ~BlkDirty;
1629 }
1630
1631 return true;
1632}
1633
1634bool
1635Cache::invalidateVisitor(CacheBlk &blk)
1636{
1637
1638 if (blk.isDirty())
1639 warn_once("Invalidating dirty cache lines. Expect things to break.\n");
1640
1641 if (blk.isValid()) {
1642 assert(!blk.isDirty());
1643 tags->invalidate(&blk);
1644 blk.invalidate();
1645 }
1646
1647 return true;
1648}
1649
1650CacheBlk*
1651Cache::allocateBlock(Addr addr, bool is_secure, PacketList &writebacks)
1652{
1653 CacheBlk *blk = tags->findVictim(addr);
1654
1655 // It is valid to return NULL if there is no victim
1656 if (!blk)
1657 return nullptr;
1658
1659 if (blk->isValid()) {
1660 Addr repl_addr = tags->regenerateBlkAddr(blk->tag, blk->set);
1661 MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
1662 if (repl_mshr) {
1663 // must be an outstanding upgrade request
1664 // on a block we're about to replace...
1665 assert(!blk->isWritable() || blk->isDirty());
1666 assert(repl_mshr->needsExclusive());
1667 // too hard to replace block with transient state
1668 // allocation failed, block not inserted
1669 return NULL;
1670 } else {
1671 DPRINTF(Cache, "replacement: replacing %#llx (%s) with %#llx (%s): %s\n",
1672 repl_addr, blk->isSecure() ? "s" : "ns",
1673 addr, is_secure ? "s" : "ns",
1674 blk->isDirty() ? "writeback" : "clean");
1675
1676 // Will send up Writeback/CleanEvict snoops via isCachedAbove
1677 // when pushing this writeback list into the write buffer.
1678 if (blk->isDirty() || writebackClean) {
1679 // Save writeback packet for handling by caller
1680 writebacks.push_back(writebackBlk(blk));
1681 } else {
1682 writebacks.push_back(cleanEvictBlk(blk));
1683 }
1684 }
1685 }
1686
1687 return blk;
1688}
1689
1690void
1691Cache::invalidateBlock(CacheBlk *blk)
1692{
1693 if (blk != tempBlock)
1694 tags->invalidate(blk);
1695 blk->invalidate();
1696}
1697
1698// Note that the reason we return a list of writebacks rather than
1699// inserting them directly in the write buffer is that this function
1700// is called by both atomic and timing-mode accesses, and in atomic
1701// mode we don't mess with the write buffer (we just perform the
1702// writebacks atomically once the original request is complete).
1703CacheBlk*
1704Cache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
1705 bool allocate)
1706{
1707 assert(pkt->isResponse() || pkt->cmd == MemCmd::WriteLineReq);
1708 Addr addr = pkt->getAddr();
1709 bool is_secure = pkt->isSecure();
1710#if TRACING_ON
1711 CacheBlk::State old_state = blk ? blk->status : 0;
1712#endif
1713
1714 // When handling a fill, discard any CleanEvicts for the
1715 // same address in write buffer.
1716 Addr M5_VAR_USED blk_addr = blockAlign(pkt->getAddr());
1717 std::vector<MSHR *> M5_VAR_USED wbs;
1718 assert (!writeBuffer.findMatches(blk_addr, is_secure, wbs));
1719
1720 if (blk == NULL) {
1721 // better have read new data...
1722 assert(pkt->hasData());
1723
1724 // only read responses and write-line requests have data;
1725 // note that we don't write the data here for write-line - that
1726 // happens in the subsequent satisfyCpuSideRequest.
1727 assert(pkt->isRead() || pkt->cmd == MemCmd::WriteLineReq);
1728
1729 // need to do a replacement if allocating, otherwise we stick
1730 // with the temporary storage
1731 blk = allocate ? allocateBlock(addr, is_secure, writebacks) : NULL;
1732
1733 if (blk == NULL) {
1734 // No replaceable block or a mostly exclusive
1735 // cache... just use temporary storage to complete the
1736 // current request and then get rid of it
1737 assert(!tempBlock->isValid());
1738 blk = tempBlock;
1739 tempBlock->set = tags->extractSet(addr);
1740 tempBlock->tag = tags->extractTag(addr);
1741 // @todo: set security state as well...
1742 DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
1743 is_secure ? "s" : "ns");
1744 } else {
1745 tags->insertBlock(pkt, blk);
1746 }
1747
1748 // we should never be overwriting a valid block
1749 assert(!blk->isValid());
1750 } else {
1751 // existing block... probably an upgrade
1752 assert(blk->tag == tags->extractTag(addr));
1753 // either we're getting new data or the block should already be valid
1754 assert(pkt->hasData() || blk->isValid());
1755 // don't clear block status... if block is already dirty we
1756 // don't want to lose that
1757 }
1758
1759 if (is_secure)
1760 blk->status |= BlkSecure;
1761 blk->status |= BlkValid | BlkReadable;
1762
1763 // sanity check for whole-line writes, which should always be
1764 // marked as writable as part of the fill, and then later marked
1765 // dirty as part of satisfyCpuSideRequest
1766 if (pkt->cmd == MemCmd::WriteLineReq) {
1767 assert(!pkt->sharedAsserted());
1768 // at the moment other caches do not respond to the
1769 // invalidation requests corresponding to a whole-line write
1770 assert(!pkt->memInhibitAsserted());
1771 }
1772
1773 if (!pkt->sharedAsserted()) {
1774 // we could get non-shared responses from memory (rather than
1775 // a cache) even in a read-only cache, note that we set this
1776 // bit even for a read-only cache as we use it to represent
1777 // the exclusive state
1778 blk->status |= BlkWritable;
1779
1780 // If we got this via cache-to-cache transfer (i.e., from a
1781 // cache that was an owner) and took away that owner's copy,
1782 // then we need to write it back. Normally this happens
1783 // anyway as a side effect of getting a copy to write it, but
1784 // there are cases (such as failed store conditionals or
1785 // compare-and-swaps) where we'll demand an exclusive copy but
1786 // end up not writing it.
1787 if (pkt->memInhibitAsserted()) {
1788 blk->status |= BlkDirty;
1789
1790 chatty_assert(!isReadOnly, "Should never see dirty snoop response "
1791 "in read-only cache %s\n", name());
1792 }
1793 }
1794
1795 DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
1796 addr, is_secure ? "s" : "ns", old_state, blk->print());
1797
1798 // if we got new data, copy it in (checking for a read response
1799 // and a response that has data is the same in the end)
1800 if (pkt->isRead()) {
1801 // sanity checks
1802 assert(pkt->hasData());
1803 assert(pkt->getSize() == blkSize);
1804
1805 std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
1806 }
1807 // We pay for fillLatency here.
1808 blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
1809 pkt->payloadDelay;
1810
1811 return blk;
1812}
1813
1814
1815/////////////////////////////////////////////////////
1816//
1817// Snoop path: requests coming in from the memory side
1818//
1819/////////////////////////////////////////////////////
1820
1821void
1822Cache::doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data,
1823 bool already_copied, bool pending_inval)
1824{
1825 // sanity check
1826 assert(req_pkt->isRequest());
1827 assert(req_pkt->needsResponse());
1828
1829 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
1830 req_pkt->cmdString(), req_pkt->getAddr(), req_pkt->getSize());
1831 // timing-mode snoop responses require a new packet, unless we
1832 // already made a copy...
1833 PacketPtr pkt = req_pkt;
1834 if (!already_copied)
1835 // do not clear flags, and allocate space for data if the
1836 // packet needs it (the only packets that carry data are read
1837 // responses)
1838 pkt = new Packet(req_pkt, false, req_pkt->isRead());
1839
1840 assert(req_pkt->req->isUncacheable() || req_pkt->isInvalidate() ||
1841 pkt->sharedAsserted());
1842 pkt->makeTimingResponse();
1843 if (pkt->isRead()) {
1844 pkt->setDataFromBlock(blk_data, blkSize);
1845 }
1846 if (pkt->cmd == MemCmd::ReadResp && pending_inval) {
1847 // Assume we defer a response to a read from a far-away cache
1848 // A, then later defer a ReadExcl from a cache B on the same
1849 // bus as us. We'll assert MemInhibit in both cases, but in
1850 // the latter case MemInhibit will keep the invalidation from
1851 // reaching cache A. This special response tells cache A that
1852 // it gets the block to satisfy its read, but must immediately
1853 // invalidate it.
1854 pkt->cmd = MemCmd::ReadRespWithInvalidate;
1855 }
1856 // Here we consider forward_time, paying for just forward latency and
1857 // also charging the delay provided by the xbar.
1858 // forward_time is used as send_time in next allocateWriteBuffer().
1859 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
1860 // Here we reset the timing of the packet.
1861 pkt->headerDelay = pkt->payloadDelay = 0;
1862 DPRINTF(Cache, "%s created response: %s addr %#llx size %d tick: %lu\n",
1863 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
1864 forward_time);
1865 memSidePort->schedTimingSnoopResp(pkt, forward_time, true);
1866}
1867
1868uint32_t
1869Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing,
1870 bool is_deferred, bool pending_inval)
1871{
1872 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
1873 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
1874 // deferred snoops can only happen in timing mode
1875 assert(!(is_deferred && !is_timing));
1876 // pending_inval only makes sense on deferred snoops
1877 assert(!(pending_inval && !is_deferred));
1878 assert(pkt->isRequest());
1879
1880 // the packet may get modified if we or a forwarded snooper
1881 // responds in atomic mode, so remember a few things about the
1882 // original packet up front
1883 bool invalidate = pkt->isInvalidate();
1884 bool M5_VAR_USED needs_exclusive = pkt->needsExclusive();
1885
1886 uint32_t snoop_delay = 0;
1887
1888 if (forwardSnoops) {
1889 // first propagate snoop upward to see if anyone above us wants to
1890 // handle it. save & restore packet src since it will get
1891 // rewritten to be relative to cpu-side bus (if any)
1892 bool alreadyResponded = pkt->memInhibitAsserted();
1893 if (is_timing) {
1894 // copy the packet so that we can clear any flags before
1895 // forwarding it upwards, we also allocate data (passing
1896 // the pointer along in case of static data), in case
1897 // there is a snoop hit in upper levels
1898 Packet snoopPkt(pkt, true, true);
1899 snoopPkt.setExpressSnoop();
| 572 // forwardLatency is set here because there is a response from an
573 // upper level cache.
574 // To pay the delay that occurs if the packet comes from the bus,
575 // we charge also headerDelay.
576 Tick snoop_resp_time = clockEdge(forwardLatency) + pkt->headerDelay;
577 // Reset the timing of the packet.
578 pkt->headerDelay = pkt->payloadDelay = 0;
579 memSidePort->schedTimingSnoopResp(pkt, snoop_resp_time);
580}
581
582void
583Cache::promoteWholeLineWrites(PacketPtr pkt)
584{
585 // Cache line clearing instructions
586 if (doFastWrites && (pkt->cmd == MemCmd::WriteReq) &&
587 (pkt->getSize() == blkSize) && (pkt->getOffset(blkSize) == 0)) {
588 pkt->cmd = MemCmd::WriteLineReq;
589 DPRINTF(Cache, "packet promoted from Write to WriteLineReq\n");
590 }
591}
592
593bool
594Cache::recvTimingReq(PacketPtr pkt)
595{
596 DPRINTF(CacheTags, "%s tags: %s\n", __func__, tags->print());
597
598 assert(pkt->isRequest());
599
600 // Just forward the packet if caches are disabled.
601 if (system->bypassCaches()) {
602 // @todo This should really enqueue the packet rather
603 bool M5_VAR_USED success = memSidePort->sendTimingReq(pkt);
604 assert(success);
605 return true;
606 }
607
608 promoteWholeLineWrites(pkt);
609
610 if (pkt->memInhibitAsserted()) {
611 // a cache above us (but not where the packet came from) is
612 // responding to the request
613 DPRINTF(Cache, "mem inhibited on addr %#llx (%s): not responding\n",
614 pkt->getAddr(), pkt->isSecure() ? "s" : "ns");
615
616 // if the packet needs exclusive, and the cache that has
617 // promised to respond (setting the inhibit flag) is not
618 // providing exclusive (it is in O vs M state), we know that
619 // there may be other shared copies in the system; go out and
620 // invalidate them all
621 if (pkt->needsExclusive() && !pkt->isSupplyExclusive()) {
622 // create a downstream express snoop with cleared packet
623 // flags, there is no need to allocate any data as the
624 // packet is merely used to co-ordinate state transitions
625 Packet *snoop_pkt = new Packet(pkt, true, false);
626
627 // also reset the bus time that the original packet has
628 // not yet paid for
629 snoop_pkt->headerDelay = snoop_pkt->payloadDelay = 0;
630
631 // make this an instantaneous express snoop, and let the
632 // other caches in the system know that the packet is
633 // inhibited, because we have found the authorative copy
634 // (O) that will supply the right data
635 snoop_pkt->setExpressSnoop();
636 snoop_pkt->assertMemInhibit();
637
638 // this express snoop travels towards the memory, and at
639 // every crossbar it is snooped upwards thus reaching
640 // every cache in the system
641 bool M5_VAR_USED success = memSidePort->sendTimingReq(snoop_pkt);
642 // express snoops always succeed
643 assert(success);
644
645 // main memory will delete the packet
646 }
647
648 // queue for deletion, as the sending cache is still relying
649 // on the packet
650 pendingDelete.reset(pkt);
651
652 // no need to take any action in this particular cache as the
653 // caches along the path to memory are allowed to keep lines
654 // in a shared state, and a cache above us already committed
655 // to responding
656 return true;
657 }
658
659 // anything that is merely forwarded pays for the forward latency and
660 // the delay provided by the crossbar
661 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
662
663 // We use lookupLatency here because it is used to specify the latency
664 // to access.
665 Cycles lat = lookupLatency;
666 CacheBlk *blk = NULL;
667 bool satisfied = false;
668 {
669 PacketList writebacks;
670 // Note that lat is passed by reference here. The function
671 // access() calls accessBlock() which can modify lat value.
672 satisfied = access(pkt, blk, lat, writebacks);
673
674 // copy writebacks to write buffer here to ensure they logically
675 // proceed anything happening below
676 doWritebacks(writebacks, forward_time);
677 }
678
679 // Here we charge the headerDelay that takes into account the latencies
680 // of the bus, if the packet comes from it.
681 // The latency charged it is just lat that is the value of lookupLatency
682 // modified by access() function, or if not just lookupLatency.
683 // In case of a hit we are neglecting response latency.
684 // In case of a miss we are neglecting forward latency.
685 Tick request_time = clockEdge(lat) + pkt->headerDelay;
686 // Here we reset the timing of the packet.
687 pkt->headerDelay = pkt->payloadDelay = 0;
688
689 // track time of availability of next prefetch, if any
690 Tick next_pf_time = MaxTick;
691
692 bool needsResponse = pkt->needsResponse();
693
694 if (satisfied) {
695 // should never be satisfying an uncacheable access as we
696 // flush and invalidate any existing block as part of the
697 // lookup
698 assert(!pkt->req->isUncacheable());
699
700 // hit (for all other request types)
701
702 if (prefetcher && (prefetchOnAccess || (blk && blk->wasPrefetched()))) {
703 if (blk)
704 blk->status &= ~BlkHWPrefetched;
705
706 // Don't notify on SWPrefetch
707 if (!pkt->cmd.isSWPrefetch())
708 next_pf_time = prefetcher->notify(pkt);
709 }
710
711 if (needsResponse) {
712 pkt->makeTimingResponse();
713 // @todo: Make someone pay for this
714 pkt->headerDelay = pkt->payloadDelay = 0;
715
716 // In this case we are considering request_time that takes
717 // into account the delay of the xbar, if any, and just
718 // lat, neglecting responseLatency, modelling hit latency
719 // just as lookupLatency or or the value of lat overriden
720 // by access(), that calls accessBlock() function.
721 cpuSidePort->schedTimingResp(pkt, request_time, true);
722 } else {
723 DPRINTF(Cache, "%s satisfied %s addr %#llx, no response needed\n",
724 __func__, pkt->cmdString(), pkt->getAddr(),
725 pkt->getSize());
726
727 // queue the packet for deletion, as the sending cache is
728 // still relying on it; if the block is found in access(),
729 // CleanEvict and Writeback messages will be deleted
730 // here as well
731 pendingDelete.reset(pkt);
732 }
733 } else {
734 // miss
735
736 Addr blk_addr = blockAlign(pkt->getAddr());
737
738 // ignore any existing MSHR if we are dealing with an
739 // uncacheable request
740 MSHR *mshr = pkt->req->isUncacheable() ? nullptr :
741 mshrQueue.findMatch(blk_addr, pkt->isSecure());
742
743 // Software prefetch handling:
744 // To keep the core from waiting on data it won't look at
745 // anyway, send back a response with dummy data. Miss handling
746 // will continue asynchronously. Unfortunately, the core will
747 // insist upon freeing original Packet/Request, so we have to
748 // create a new pair with a different lifecycle. Note that this
749 // processing happens before any MSHR munging on the behalf of
750 // this request because this new Request will be the one stored
751 // into the MSHRs, not the original.
752 if (pkt->cmd.isSWPrefetch()) {
753 assert(needsResponse);
754 assert(pkt->req->hasPaddr());
755 assert(!pkt->req->isUncacheable());
756
757 // There's no reason to add a prefetch as an additional target
758 // to an existing MSHR. If an outstanding request is already
759 // in progress, there is nothing for the prefetch to do.
760 // If this is the case, we don't even create a request at all.
761 PacketPtr pf = nullptr;
762
763 if (!mshr) {
764 // copy the request and create a new SoftPFReq packet
765 RequestPtr req = new Request(pkt->req->getPaddr(),
766 pkt->req->getSize(),
767 pkt->req->getFlags(),
768 pkt->req->masterId());
769 pf = new Packet(req, pkt->cmd);
770 pf->allocate();
771 assert(pf->getAddr() == pkt->getAddr());
772 assert(pf->getSize() == pkt->getSize());
773 }
774
775 pkt->makeTimingResponse();
776 // for debugging, set all the bits in the response data
777 // (also keeps valgrind from complaining when debugging settings
778 // print out instruction results)
779 std::memset(pkt->getPtr<uint8_t>(), 0xFF, pkt->getSize());
780 // request_time is used here, taking into account lat and the delay
781 // charged if the packet comes from the xbar.
782 cpuSidePort->schedTimingResp(pkt, request_time, true);
783
784 // If an outstanding request is in progress (we found an
785 // MSHR) this is set to null
786 pkt = pf;
787 }
788
789 if (mshr) {
790 /// MSHR hit
791 /// @note writebacks will be checked in getNextMSHR()
792 /// for any conflicting requests to the same block
793
794 //@todo remove hw_pf here
795
796 // Coalesce unless it was a software prefetch (see above).
797 if (pkt) {
798 assert(!pkt->isWriteback());
799 // CleanEvicts corresponding to blocks which have
800 // outstanding requests in MSHRs are simply sunk here
801 if (pkt->cmd == MemCmd::CleanEvict) {
802 pendingDelete.reset(pkt);
803 } else {
804 DPRINTF(Cache, "%s coalescing MSHR for %s addr %#llx size %d\n",
805 __func__, pkt->cmdString(), pkt->getAddr(),
806 pkt->getSize());
807
808 assert(pkt->req->masterId() < system->maxMasters());
809 mshr_hits[pkt->cmdToIndex()][pkt->req->masterId()]++;
810 if (mshr->threadNum != 0/*pkt->req->threadId()*/) {
811 mshr->threadNum = -1;
812 }
813 // We use forward_time here because it is the same
814 // considering new targets. We have multiple
815 // requests for the same address here. It
816 // specifies the latency to allocate an internal
817 // buffer and to schedule an event to the queued
818 // port and also takes into account the additional
819 // delay of the xbar.
820 mshr->allocateTarget(pkt, forward_time, order++,
821 allocOnFill(pkt->cmd));
822 if (mshr->getNumTargets() == numTarget) {
823 noTargetMSHR = mshr;
824 setBlocked(Blocked_NoTargets);
825 // need to be careful with this... if this mshr isn't
826 // ready yet (i.e. time > curTick()), we don't want to
827 // move it ahead of mshrs that are ready
828 // mshrQueue.moveToFront(mshr);
829 }
830 }
831 // We should call the prefetcher reguardless if the request is
832 // satisfied or not, reguardless if the request is in the MSHR or
833 // not. The request could be a ReadReq hit, but still not
834 // satisfied (potentially because of a prior write to the same
835 // cache line. So, even when not satisfied, tehre is an MSHR
836 // already allocated for this, we need to let the prefetcher know
837 // about the request
838 if (prefetcher) {
839 // Don't notify on SWPrefetch
840 if (!pkt->cmd.isSWPrefetch())
841 next_pf_time = prefetcher->notify(pkt);
842 }
843 }
844 } else {
845 // no MSHR
846 assert(pkt->req->masterId() < system->maxMasters());
847 if (pkt->req->isUncacheable()) {
848 mshr_uncacheable[pkt->cmdToIndex()][pkt->req->masterId()]++;
849 } else {
850 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
851 }
852
853 if (pkt->isEviction() ||
854 (pkt->req->isUncacheable() && pkt->isWrite())) {
855 // We use forward_time here because there is an
856 // uncached memory write, forwarded to WriteBuffer.
857 allocateWriteBuffer(pkt, forward_time);
858 } else {
859 if (blk && blk->isValid()) {
860 // should have flushed and have no valid block
861 assert(!pkt->req->isUncacheable());
862
863 // If we have a write miss to a valid block, we
864 // need to mark the block non-readable. Otherwise
865 // if we allow reads while there's an outstanding
866 // write miss, the read could return stale data
867 // out of the cache block... a more aggressive
868 // system could detect the overlap (if any) and
869 // forward data out of the MSHRs, but we don't do
870 // that yet. Note that we do need to leave the
871 // block valid so that it stays in the cache, in
872 // case we get an upgrade response (and hence no
873 // new data) when the write miss completes.
874 // As long as CPUs do proper store/load forwarding
875 // internally, and have a sufficiently weak memory
876 // model, this is probably unnecessary, but at some
877 // point it must have seemed like we needed it...
878 assert(pkt->needsExclusive());
879 assert(!blk->isWritable());
880 blk->status &= ~BlkReadable;
881 }
882 // Here we are using forward_time, modelling the latency of
883 // a miss (outbound) just as forwardLatency, neglecting the
884 // lookupLatency component.
885 allocateMissBuffer(pkt, forward_time);
886 }
887
888 if (prefetcher) {
889 // Don't notify on SWPrefetch
890 if (!pkt->cmd.isSWPrefetch())
891 next_pf_time = prefetcher->notify(pkt);
892 }
893 }
894 }
895
896 if (next_pf_time != MaxTick)
897 schedMemSideSendEvent(next_pf_time);
898
899 return true;
900}
901
902
903// See comment in cache.hh.
904PacketPtr
905Cache::getBusPacket(PacketPtr cpu_pkt, CacheBlk *blk,
906 bool needsExclusive) const
907{
908 bool blkValid = blk && blk->isValid();
909
910 if (cpu_pkt->req->isUncacheable()) {
911 // note that at the point we see the uncacheable request we
912 // flush any block, but there could be an outstanding MSHR,
913 // and the cache could have filled again before we actually
914 // send out the forwarded uncacheable request (blk could thus
915 // be non-null)
916 return NULL;
917 }
918
919 if (!blkValid &&
920 (cpu_pkt->isUpgrade() ||
921 cpu_pkt->isEviction())) {
922 // Writebacks that weren't allocated in access() and upgrades
923 // from upper-level caches that missed completely just go
924 // through.
925 return NULL;
926 }
927
928 assert(cpu_pkt->needsResponse());
929
930 MemCmd cmd;
931 // @TODO make useUpgrades a parameter.
932 // Note that ownership protocols require upgrade, otherwise a
933 // write miss on a shared owned block will generate a ReadExcl,
934 // which will clobber the owned copy.
935 const bool useUpgrades = true;
936 if (blkValid && useUpgrades) {
937 // only reason to be here is that blk is shared
938 // (read-only) and we need exclusive
939 assert(needsExclusive);
940 assert(!blk->isWritable());
941 cmd = cpu_pkt->isLLSC() ? MemCmd::SCUpgradeReq : MemCmd::UpgradeReq;
942 } else if (cpu_pkt->cmd == MemCmd::SCUpgradeFailReq ||
943 cpu_pkt->cmd == MemCmd::StoreCondFailReq) {
944 // Even though this SC will fail, we still need to send out the
945 // request and get the data to supply it to other snoopers in the case
946 // where the determination the StoreCond fails is delayed due to
947 // all caches not being on the same local bus.
948 cmd = MemCmd::SCUpgradeFailReq;
949 } else if (cpu_pkt->cmd == MemCmd::WriteLineReq) {
950 // forward as invalidate to all other caches, this gives us
951 // the line in exclusive state, and invalidates all other
952 // copies
953 cmd = MemCmd::InvalidateReq;
954 } else {
955 // block is invalid
956 cmd = needsExclusive ? MemCmd::ReadExReq :
957 (isReadOnly ? MemCmd::ReadCleanReq : MemCmd::ReadSharedReq);
958 }
959 PacketPtr pkt = new Packet(cpu_pkt->req, cmd, blkSize);
960
961 // if there are sharers in the upper levels, pass that info downstream
962 if (cpu_pkt->sharedAsserted()) {
963 // note that cpu_pkt may have spent a considerable time in the
964 // MSHR queue and that the information could possibly be out
965 // of date, however, there is no harm in conservatively
966 // assuming the block is shared
967 pkt->assertShared();
968 DPRINTF(Cache, "%s passing shared from %s to %s addr %#llx size %d\n",
969 __func__, cpu_pkt->cmdString(), pkt->cmdString(),
970 pkt->getAddr(), pkt->getSize());
971 }
972
973 // the packet should be block aligned
974 assert(pkt->getAddr() == blockAlign(pkt->getAddr()));
975
976 pkt->allocate();
977 DPRINTF(Cache, "%s created %s from %s for addr %#llx size %d\n",
978 __func__, pkt->cmdString(), cpu_pkt->cmdString(), pkt->getAddr(),
979 pkt->getSize());
980 return pkt;
981}
982
983
984Tick
985Cache::recvAtomic(PacketPtr pkt)
986{
987 // We are in atomic mode so we pay just for lookupLatency here.
988 Cycles lat = lookupLatency;
989 // @TODO: make this a parameter
990 bool last_level_cache = false;
991
992 // Forward the request if the system is in cache bypass mode.
993 if (system->bypassCaches())
994 return ticksToCycles(memSidePort->sendAtomic(pkt));
995
996 promoteWholeLineWrites(pkt);
997
998 if (pkt->memInhibitAsserted()) {
999 // have to invalidate ourselves and any lower caches even if
1000 // upper cache will be responding
1001 if (pkt->isInvalidate()) {
1002 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
1003 if (blk && blk->isValid()) {
1004 tags->invalidate(blk);
1005 blk->invalidate();
1006 DPRINTF(Cache, "rcvd mem-inhibited %s on %#llx (%s):"
1007 " invalidating\n",
1008 pkt->cmdString(), pkt->getAddr(),
1009 pkt->isSecure() ? "s" : "ns");
1010 }
1011 if (!last_level_cache) {
1012 DPRINTF(Cache, "forwarding mem-inhibited %s on %#llx (%s)\n",
1013 pkt->cmdString(), pkt->getAddr(),
1014 pkt->isSecure() ? "s" : "ns");
1015 lat += ticksToCycles(memSidePort->sendAtomic(pkt));
1016 }
1017 } else {
1018 DPRINTF(Cache, "rcvd mem-inhibited %s on %#llx: not responding\n",
1019 pkt->cmdString(), pkt->getAddr());
1020 }
1021
1022 return lat * clockPeriod();
1023 }
1024
1025 // should assert here that there are no outstanding MSHRs or
1026 // writebacks... that would mean that someone used an atomic
1027 // access in timing mode
1028
1029 CacheBlk *blk = NULL;
1030 PacketList writebacks;
1031 bool satisfied = access(pkt, blk, lat, writebacks);
1032
1033 // handle writebacks resulting from the access here to ensure they
1034 // logically proceed anything happening below
1035 doWritebacksAtomic(writebacks);
1036
1037 if (!satisfied) {
1038 // MISS
1039
1040 PacketPtr bus_pkt = getBusPacket(pkt, blk, pkt->needsExclusive());
1041
1042 bool is_forward = (bus_pkt == NULL);
1043
1044 if (is_forward) {
1045 // just forwarding the same request to the next level
1046 // no local cache operation involved
1047 bus_pkt = pkt;
1048 }
1049
1050 DPRINTF(Cache, "Sending an atomic %s for %#llx (%s)\n",
1051 bus_pkt->cmdString(), bus_pkt->getAddr(),
1052 bus_pkt->isSecure() ? "s" : "ns");
1053
1054#if TRACING_ON
1055 CacheBlk::State old_state = blk ? blk->status : 0;
1056#endif
1057
1058 lat += ticksToCycles(memSidePort->sendAtomic(bus_pkt));
1059
1060 // We are now dealing with the response handling
1061 DPRINTF(Cache, "Receive response: %s for addr %#llx (%s) in state %i\n",
1062 bus_pkt->cmdString(), bus_pkt->getAddr(),
1063 bus_pkt->isSecure() ? "s" : "ns",
1064 old_state);
1065
1066 // If packet was a forward, the response (if any) is already
1067 // in place in the bus_pkt == pkt structure, so we don't need
1068 // to do anything. Otherwise, use the separate bus_pkt to
1069 // generate response to pkt and then delete it.
1070 if (!is_forward) {
1071 if (pkt->needsResponse()) {
1072 assert(bus_pkt->isResponse());
1073 if (bus_pkt->isError()) {
1074 pkt->makeAtomicResponse();
1075 pkt->copyError(bus_pkt);
1076 } else if (pkt->cmd == MemCmd::InvalidateReq) {
1077 if (blk) {
1078 // invalidate response to a cache that received
1079 // an invalidate request
1080 satisfyCpuSideRequest(pkt, blk);
1081 }
1082 } else if (pkt->cmd == MemCmd::WriteLineReq) {
1083 // note the use of pkt, not bus_pkt here.
1084
1085 // write-line request to the cache that promoted
1086 // the write to a whole line
1087 blk = handleFill(pkt, blk, writebacks,
1088 allocOnFill(pkt->cmd));
1089 satisfyCpuSideRequest(pkt, blk);
1090 } else if (bus_pkt->isRead() ||
1091 bus_pkt->cmd == MemCmd::UpgradeResp) {
1092 // we're updating cache state to allow us to
1093 // satisfy the upstream request from the cache
1094 blk = handleFill(bus_pkt, blk, writebacks,
1095 allocOnFill(pkt->cmd));
1096 satisfyCpuSideRequest(pkt, blk);
1097 } else {
1098 // we're satisfying the upstream request without
1099 // modifying cache state, e.g., a write-through
1100 pkt->makeAtomicResponse();
1101 }
1102 }
1103 delete bus_pkt;
1104 }
1105 }
1106
1107 // Note that we don't invoke the prefetcher at all in atomic mode.
1108 // It's not clear how to do it properly, particularly for
1109 // prefetchers that aggressively generate prefetch candidates and
1110 // rely on bandwidth contention to throttle them; these will tend
1111 // to pollute the cache in atomic mode since there is no bandwidth
1112 // contention. If we ever do want to enable prefetching in atomic
1113 // mode, though, this is the place to do it... see timingAccess()
1114 // for an example (though we'd want to issue the prefetch(es)
1115 // immediately rather than calling requestMemSideBus() as we do
1116 // there).
1117
1118 // do any writebacks resulting from the response handling
1119 doWritebacksAtomic(writebacks);
1120
1121 // if we used temp block, check to see if its valid and if so
1122 // clear it out, but only do so after the call to recvAtomic is
1123 // finished so that any downstream observers (such as a snoop
1124 // filter), first see the fill, and only then see the eviction
1125 if (blk == tempBlock && tempBlock->isValid()) {
1126 // the atomic CPU calls recvAtomic for fetch and load/store
1127 // sequentuially, and we may already have a tempBlock
1128 // writeback from the fetch that we have not yet sent
1129 if (tempBlockWriteback) {
1130 // if that is the case, write the prevoius one back, and
1131 // do not schedule any new event
1132 writebackTempBlockAtomic();
1133 } else {
1134 // the writeback/clean eviction happens after the call to
1135 // recvAtomic has finished (but before any successive
1136 // calls), so that the response handling from the fill is
1137 // allowed to happen first
1138 schedule(writebackTempBlockAtomicEvent, curTick());
1139 }
1140
1141 tempBlockWriteback = (blk->isDirty() || writebackClean) ?
1142 writebackBlk(blk) : cleanEvictBlk(blk);
1143 blk->invalidate();
1144 }
1145
1146 if (pkt->needsResponse()) {
1147 pkt->makeAtomicResponse();
1148 }
1149
1150 return lat * clockPeriod();
1151}
1152
1153
1154void
1155Cache::functionalAccess(PacketPtr pkt, bool fromCpuSide)
1156{
1157 if (system->bypassCaches()) {
1158 // Packets from the memory side are snoop request and
1159 // shouldn't happen in bypass mode.
1160 assert(fromCpuSide);
1161
1162 // The cache should be flushed if we are in cache bypass mode,
1163 // so we don't need to check if we need to update anything.
1164 memSidePort->sendFunctional(pkt);
1165 return;
1166 }
1167
1168 Addr blk_addr = blockAlign(pkt->getAddr());
1169 bool is_secure = pkt->isSecure();
1170 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
1171 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
1172
1173 pkt->pushLabel(name());
1174
1175 CacheBlkPrintWrapper cbpw(blk);
1176
1177 // Note that just because an L2/L3 has valid data doesn't mean an
1178 // L1 doesn't have a more up-to-date modified copy that still
1179 // needs to be found. As a result we always update the request if
1180 // we have it, but only declare it satisfied if we are the owner.
1181
1182 // see if we have data at all (owned or otherwise)
1183 bool have_data = blk && blk->isValid()
1184 && pkt->checkFunctional(&cbpw, blk_addr, is_secure, blkSize,
1185 blk->data);
1186
1187 // data we have is dirty if marked as such or if valid & ownership
1188 // pending due to outstanding UpgradeReq
1189 bool have_dirty =
1190 have_data && (blk->isDirty() ||
1191 (mshr && mshr->inService && mshr->isPendingDirty()));
1192
1193 bool done = have_dirty
1194 || cpuSidePort->checkFunctional(pkt)
1195 || mshrQueue.checkFunctional(pkt, blk_addr)
1196 || writeBuffer.checkFunctional(pkt, blk_addr)
1197 || memSidePort->checkFunctional(pkt);
1198
1199 DPRINTF(Cache, "functional %s %#llx (%s) %s%s%s\n",
1200 pkt->cmdString(), pkt->getAddr(), is_secure ? "s" : "ns",
1201 (blk && blk->isValid()) ? "valid " : "",
1202 have_data ? "data " : "", done ? "done " : "");
1203
1204 // We're leaving the cache, so pop cache->name() label
1205 pkt->popLabel();
1206
1207 if (done) {
1208 pkt->makeResponse();
1209 } else {
1210 // if it came as a request from the CPU side then make sure it
1211 // continues towards the memory side
1212 if (fromCpuSide) {
1213 memSidePort->sendFunctional(pkt);
1214 } else if (forwardSnoops && cpuSidePort->isSnooping()) {
1215 // if it came from the memory side, it must be a snoop request
1216 // and we should only forward it if we are forwarding snoops
1217 cpuSidePort->sendFunctionalSnoop(pkt);
1218 }
1219 }
1220}
1221
1222
1223/////////////////////////////////////////////////////
1224//
1225// Response handling: responses from the memory side
1226//
1227/////////////////////////////////////////////////////
1228
1229
1230void
1231Cache::recvTimingResp(PacketPtr pkt)
1232{
1233 assert(pkt->isResponse());
1234
1235 // all header delay should be paid for by the crossbar, unless
1236 // this is a prefetch response from above
1237 panic_if(pkt->headerDelay != 0 && pkt->cmd != MemCmd::HardPFResp,
1238 "%s saw a non-zero packet delay\n", name());
1239
1240 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
1241 bool is_error = pkt->isError();
1242
1243 assert(mshr);
1244
1245 if (is_error) {
1246 DPRINTF(Cache, "Cache received packet with error for addr %#llx (%s), "
1247 "cmd: %s\n", pkt->getAddr(), pkt->isSecure() ? "s" : "ns",
1248 pkt->cmdString());
1249 }
1250
1251 DPRINTF(Cache, "Handling response %s for addr %#llx size %d (%s)\n",
1252 pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
1253 pkt->isSecure() ? "s" : "ns");
1254
1255 MSHRQueue *mq = mshr->queue;
1256 bool wasFull = mq->isFull();
1257
1258 if (mshr == noTargetMSHR) {
1259 // we always clear at least one target
1260 clearBlocked(Blocked_NoTargets);
1261 noTargetMSHR = NULL;
1262 }
1263
1264 // Initial target is used just for stats
1265 MSHR::Target *initial_tgt = mshr->getTarget();
1266 int stats_cmd_idx = initial_tgt->pkt->cmdToIndex();
1267 Tick miss_latency = curTick() - initial_tgt->recvTime;
1268 PacketList writebacks;
1269 // We need forward_time here because we have a call of
1270 // allocateWriteBuffer() that need this parameter to specify the
1271 // time to request the bus. In this case we use forward latency
1272 // because there is a writeback. We pay also here for headerDelay
1273 // that is charged of bus latencies if the packet comes from the
1274 // bus.
1275 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
1276
1277 if (pkt->req->isUncacheable()) {
1278 assert(pkt->req->masterId() < system->maxMasters());
1279 mshr_uncacheable_lat[stats_cmd_idx][pkt->req->masterId()] +=
1280 miss_latency;
1281 } else {
1282 assert(pkt->req->masterId() < system->maxMasters());
1283 mshr_miss_latency[stats_cmd_idx][pkt->req->masterId()] +=
1284 miss_latency;
1285 }
1286
1287 // upgrade deferred targets if we got exclusive
1288 if (!pkt->sharedAsserted()) {
1289 mshr->promoteExclusive();
1290 }
1291
1292 bool is_fill = !mshr->isForward &&
1293 (pkt->isRead() || pkt->cmd == MemCmd::UpgradeResp);
1294
1295 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
1296
1297 if (is_fill && !is_error) {
1298 DPRINTF(Cache, "Block for addr %#llx being updated in Cache\n",
1299 pkt->getAddr());
1300
1301 blk = handleFill(pkt, blk, writebacks, mshr->allocOnFill);
1302 assert(blk != NULL);
1303 }
1304
1305 // allow invalidation responses originating from write-line
1306 // requests to be discarded
1307 bool is_invalidate = pkt->isInvalidate();
1308
1309 // First offset for critical word first calculations
1310 int initial_offset = initial_tgt->pkt->getOffset(blkSize);
1311
1312 while (mshr->hasTargets()) {
1313 MSHR::Target *target = mshr->getTarget();
1314 Packet *tgt_pkt = target->pkt;
1315
1316 switch (target->source) {
1317 case MSHR::Target::FromCPU:
1318 Tick completion_time;
1319 // Here we charge on completion_time the delay of the xbar if the
1320 // packet comes from it, charged on headerDelay.
1321 completion_time = pkt->headerDelay;
1322
1323 // Software prefetch handling for cache closest to core
1324 if (tgt_pkt->cmd.isSWPrefetch()) {
1325 // a software prefetch would have already been ack'd immediately
1326 // with dummy data so the core would be able to retire it.
1327 // this request completes right here, so we deallocate it.
1328 delete tgt_pkt->req;
1329 delete tgt_pkt;
1330 break; // skip response
1331 }
1332
1333 // unlike the other packet flows, where data is found in other
1334 // caches or memory and brought back, write-line requests always
1335 // have the data right away, so the above check for "is fill?"
1336 // cannot actually be determined until examining the stored MSHR
1337 // state. We "catch up" with that logic here, which is duplicated
1338 // from above.
1339 if (tgt_pkt->cmd == MemCmd::WriteLineReq) {
1340 assert(!is_error);
1341 // we got the block in exclusive state, so promote any
1342 // deferred targets if possible
1343 mshr->promoteExclusive();
1344 // NB: we use the original packet here and not the response!
1345 blk = handleFill(tgt_pkt, blk, writebacks, mshr->allocOnFill);
1346 assert(blk != NULL);
1347
1348 // treat as a fill, and discard the invalidation
1349 // response
1350 is_fill = true;
1351 is_invalidate = false;
1352 }
1353
1354 if (is_fill) {
1355 satisfyCpuSideRequest(tgt_pkt, blk,
1356 true, mshr->hasPostDowngrade());
1357
1358 // How many bytes past the first request is this one
1359 int transfer_offset =
1360 tgt_pkt->getOffset(blkSize) - initial_offset;
1361 if (transfer_offset < 0) {
1362 transfer_offset += blkSize;
1363 }
1364
1365 // If not critical word (offset) return payloadDelay.
1366 // responseLatency is the latency of the return path
1367 // from lower level caches/memory to an upper level cache or
1368 // the core.
1369 completion_time += clockEdge(responseLatency) +
1370 (transfer_offset ? pkt->payloadDelay : 0);
1371
1372 assert(!tgt_pkt->req->isUncacheable());
1373
1374 assert(tgt_pkt->req->masterId() < system->maxMasters());
1375 missLatency[tgt_pkt->cmdToIndex()][tgt_pkt->req->masterId()] +=
1376 completion_time - target->recvTime;
1377 } else if (pkt->cmd == MemCmd::UpgradeFailResp) {
1378 // failed StoreCond upgrade
1379 assert(tgt_pkt->cmd == MemCmd::StoreCondReq ||
1380 tgt_pkt->cmd == MemCmd::StoreCondFailReq ||
1381 tgt_pkt->cmd == MemCmd::SCUpgradeFailReq);
1382 // responseLatency is the latency of the return path
1383 // from lower level caches/memory to an upper level cache or
1384 // the core.
1385 completion_time += clockEdge(responseLatency) +
1386 pkt->payloadDelay;
1387 tgt_pkt->req->setExtraData(0);
1388 } else {
1389 // not a cache fill, just forwarding response
1390 // responseLatency is the latency of the return path
1391 // from lower level cahces/memory to the core.
1392 completion_time += clockEdge(responseLatency) +
1393 pkt->payloadDelay;
1394 if (pkt->isRead() && !is_error) {
1395 // sanity check
1396 assert(pkt->getAddr() == tgt_pkt->getAddr());
1397 assert(pkt->getSize() >= tgt_pkt->getSize());
1398
1399 tgt_pkt->setData(pkt->getConstPtr<uint8_t>());
1400 }
1401 }
1402 tgt_pkt->makeTimingResponse();
1403 // if this packet is an error copy that to the new packet
1404 if (is_error)
1405 tgt_pkt->copyError(pkt);
1406 if (tgt_pkt->cmd == MemCmd::ReadResp &&
1407 (is_invalidate || mshr->hasPostInvalidate())) {
1408 // If intermediate cache got ReadRespWithInvalidate,
1409 // propagate that. Response should not have
1410 // isInvalidate() set otherwise.
1411 tgt_pkt->cmd = MemCmd::ReadRespWithInvalidate;
1412 DPRINTF(Cache, "%s updated cmd to %s for addr %#llx\n",
1413 __func__, tgt_pkt->cmdString(), tgt_pkt->getAddr());
1414 }
1415 // Reset the bus additional time as it is now accounted for
1416 tgt_pkt->headerDelay = tgt_pkt->payloadDelay = 0;
1417 cpuSidePort->schedTimingResp(tgt_pkt, completion_time, true);
1418 break;
1419
1420 case MSHR::Target::FromPrefetcher:
1421 assert(tgt_pkt->cmd == MemCmd::HardPFReq);
1422 if (blk)
1423 blk->status |= BlkHWPrefetched;
1424 delete tgt_pkt->req;
1425 delete tgt_pkt;
1426 break;
1427
1428 case MSHR::Target::FromSnoop:
1429 // I don't believe that a snoop can be in an error state
1430 assert(!is_error);
1431 // response to snoop request
1432 DPRINTF(Cache, "processing deferred snoop...\n");
1433 assert(!(is_invalidate && !mshr->hasPostInvalidate()));
1434 handleSnoop(tgt_pkt, blk, true, true, mshr->hasPostInvalidate());
1435 break;
1436
1437 default:
1438 panic("Illegal target->source enum %d\n", target->source);
1439 }
1440
1441 mshr->popTarget();
1442 }
1443
1444 if (blk && blk->isValid()) {
1445 // an invalidate response stemming from a write line request
1446 // should not invalidate the block, so check if the
1447 // invalidation should be discarded
1448 if (is_invalidate || mshr->hasPostInvalidate()) {
1449 invalidateBlock(blk);
1450 } else if (mshr->hasPostDowngrade()) {
1451 blk->status &= ~BlkWritable;
1452 }
1453 }
1454
1455 if (mshr->promoteDeferredTargets()) {
1456 // avoid later read getting stale data while write miss is
1457 // outstanding.. see comment in timingAccess()
1458 if (blk) {
1459 blk->status &= ~BlkReadable;
1460 }
1461 mq = mshr->queue;
1462 mq->markPending(mshr);
1463 schedMemSideSendEvent(clockEdge() + pkt->payloadDelay);
1464 } else {
1465 mq->deallocate(mshr);
1466 if (wasFull && !mq->isFull()) {
1467 clearBlocked((BlockedCause)mq->index);
1468 }
1469
1470 // Request the bus for a prefetch if this deallocation freed enough
1471 // MSHRs for a prefetch to take place
1472 if (prefetcher && mq == &mshrQueue && mshrQueue.canPrefetch()) {
1473 Tick next_pf_time = std::max(prefetcher->nextPrefetchReadyTime(),
1474 clockEdge());
1475 if (next_pf_time != MaxTick)
1476 schedMemSideSendEvent(next_pf_time);
1477 }
1478 }
1479 // reset the xbar additional timinig as it is now accounted for
1480 pkt->headerDelay = pkt->payloadDelay = 0;
1481
1482 // copy writebacks to write buffer
1483 doWritebacks(writebacks, forward_time);
1484
1485 // if we used temp block, check to see if its valid and then clear it out
1486 if (blk == tempBlock && tempBlock->isValid()) {
1487 // We use forwardLatency here because we are copying
1488 // Writebacks/CleanEvicts to write buffer. It specifies the latency to
1489 // allocate an internal buffer and to schedule an event to the
1490 // queued port.
1491 if (blk->isDirty() || writebackClean) {
1492 PacketPtr wbPkt = writebackBlk(blk);
1493 allocateWriteBuffer(wbPkt, forward_time);
1494 // Set BLOCK_CACHED flag if cached above.
1495 if (isCachedAbove(wbPkt))
1496 wbPkt->setBlockCached();
1497 } else {
1498 PacketPtr wcPkt = cleanEvictBlk(blk);
1499 // Check to see if block is cached above. If not allocate
1500 // write buffer
1501 if (isCachedAbove(wcPkt))
1502 delete wcPkt;
1503 else
1504 allocateWriteBuffer(wcPkt, forward_time);
1505 }
1506 blk->invalidate();
1507 }
1508
1509 DPRINTF(Cache, "Leaving %s with %s for addr %#llx\n", __func__,
1510 pkt->cmdString(), pkt->getAddr());
1511 delete pkt;
1512}
1513
1514PacketPtr
1515Cache::writebackBlk(CacheBlk *blk)
1516{
1517 chatty_assert(!isReadOnly || writebackClean,
1518 "Writeback from read-only cache");
1519 assert(blk && blk->isValid() && (blk->isDirty() || writebackClean));
1520
1521 writebacks[Request::wbMasterId]++;
1522
1523 Request *req = new Request(tags->regenerateBlkAddr(blk->tag, blk->set),
1524 blkSize, 0, Request::wbMasterId);
1525 if (blk->isSecure())
1526 req->setFlags(Request::SECURE);
1527
1528 req->taskId(blk->task_id);
1529 blk->task_id= ContextSwitchTaskId::Unknown;
1530 blk->tickInserted = curTick();
1531
1532 PacketPtr pkt =
1533 new Packet(req, blk->isDirty() ?
1534 MemCmd::WritebackDirty : MemCmd::WritebackClean);
1535
1536 DPRINTF(Cache, "Create Writeback %#llx writable: %d, dirty: %d\n",
1537 pkt->getAddr(), blk->isWritable(), blk->isDirty());
1538
1539 if (blk->isWritable()) {
1540 // not asserting shared means we pass the block in modified
1541 // state, mark our own block non-writeable
1542 blk->status &= ~BlkWritable;
1543 } else {
1544 // we are in the owned state, tell the receiver
1545 pkt->assertShared();
1546 }
1547
1548 // make sure the block is not marked dirty
1549 blk->status &= ~BlkDirty;
1550
1551 pkt->allocate();
1552 std::memcpy(pkt->getPtr<uint8_t>(), blk->data, blkSize);
1553
1554 return pkt;
1555}
1556
1557PacketPtr
1558Cache::cleanEvictBlk(CacheBlk *blk)
1559{
1560 assert(!writebackClean);
1561 assert(blk && blk->isValid() && !blk->isDirty());
1562 // Creating a zero sized write, a message to the snoop filter
1563 Request *req =
1564 new Request(tags->regenerateBlkAddr(blk->tag, blk->set), blkSize, 0,
1565 Request::wbMasterId);
1566 if (blk->isSecure())
1567 req->setFlags(Request::SECURE);
1568
1569 req->taskId(blk->task_id);
1570 blk->task_id = ContextSwitchTaskId::Unknown;
1571 blk->tickInserted = curTick();
1572
1573 PacketPtr pkt = new Packet(req, MemCmd::CleanEvict);
1574 pkt->allocate();
1575 DPRINTF(Cache, "%s%s %x Create CleanEvict\n", pkt->cmdString(),
1576 pkt->req->isInstFetch() ? " (ifetch)" : "",
1577 pkt->getAddr());
1578
1579 return pkt;
1580}
1581
1582void
1583Cache::memWriteback()
1584{
1585 CacheBlkVisitorWrapper visitor(*this, &Cache::writebackVisitor);
1586 tags->forEachBlk(visitor);
1587}
1588
1589void
1590Cache::memInvalidate()
1591{
1592 CacheBlkVisitorWrapper visitor(*this, &Cache::invalidateVisitor);
1593 tags->forEachBlk(visitor);
1594}
1595
1596bool
1597Cache::isDirty() const
1598{
1599 CacheBlkIsDirtyVisitor visitor;
1600 tags->forEachBlk(visitor);
1601
1602 return visitor.isDirty();
1603}
1604
1605bool
1606Cache::writebackVisitor(CacheBlk &blk)
1607{
1608 if (blk.isDirty()) {
1609 assert(blk.isValid());
1610
1611 Request request(tags->regenerateBlkAddr(blk.tag, blk.set),
1612 blkSize, 0, Request::funcMasterId);
1613 request.taskId(blk.task_id);
1614
1615 Packet packet(&request, MemCmd::WriteReq);
1616 packet.dataStatic(blk.data);
1617
1618 memSidePort->sendFunctional(&packet);
1619
1620 blk.status &= ~BlkDirty;
1621 }
1622
1623 return true;
1624}
1625
1626bool
1627Cache::invalidateVisitor(CacheBlk &blk)
1628{
1629
1630 if (blk.isDirty())
1631 warn_once("Invalidating dirty cache lines. Expect things to break.\n");
1632
1633 if (blk.isValid()) {
1634 assert(!blk.isDirty());
1635 tags->invalidate(&blk);
1636 blk.invalidate();
1637 }
1638
1639 return true;
1640}
1641
1642CacheBlk*
1643Cache::allocateBlock(Addr addr, bool is_secure, PacketList &writebacks)
1644{
1645 CacheBlk *blk = tags->findVictim(addr);
1646
1647 // It is valid to return NULL if there is no victim
1648 if (!blk)
1649 return nullptr;
1650
1651 if (blk->isValid()) {
1652 Addr repl_addr = tags->regenerateBlkAddr(blk->tag, blk->set);
1653 MSHR *repl_mshr = mshrQueue.findMatch(repl_addr, blk->isSecure());
1654 if (repl_mshr) {
1655 // must be an outstanding upgrade request
1656 // on a block we're about to replace...
1657 assert(!blk->isWritable() || blk->isDirty());
1658 assert(repl_mshr->needsExclusive());
1659 // too hard to replace block with transient state
1660 // allocation failed, block not inserted
1661 return NULL;
1662 } else {
1663 DPRINTF(Cache, "replacement: replacing %#llx (%s) with %#llx (%s): %s\n",
1664 repl_addr, blk->isSecure() ? "s" : "ns",
1665 addr, is_secure ? "s" : "ns",
1666 blk->isDirty() ? "writeback" : "clean");
1667
1668 // Will send up Writeback/CleanEvict snoops via isCachedAbove
1669 // when pushing this writeback list into the write buffer.
1670 if (blk->isDirty() || writebackClean) {
1671 // Save writeback packet for handling by caller
1672 writebacks.push_back(writebackBlk(blk));
1673 } else {
1674 writebacks.push_back(cleanEvictBlk(blk));
1675 }
1676 }
1677 }
1678
1679 return blk;
1680}
1681
1682void
1683Cache::invalidateBlock(CacheBlk *blk)
1684{
1685 if (blk != tempBlock)
1686 tags->invalidate(blk);
1687 blk->invalidate();
1688}
1689
1690// Note that the reason we return a list of writebacks rather than
1691// inserting them directly in the write buffer is that this function
1692// is called by both atomic and timing-mode accesses, and in atomic
1693// mode we don't mess with the write buffer (we just perform the
1694// writebacks atomically once the original request is complete).
1695CacheBlk*
1696Cache::handleFill(PacketPtr pkt, CacheBlk *blk, PacketList &writebacks,
1697 bool allocate)
1698{
1699 assert(pkt->isResponse() || pkt->cmd == MemCmd::WriteLineReq);
1700 Addr addr = pkt->getAddr();
1701 bool is_secure = pkt->isSecure();
1702#if TRACING_ON
1703 CacheBlk::State old_state = blk ? blk->status : 0;
1704#endif
1705
1706 // When handling a fill, discard any CleanEvicts for the
1707 // same address in write buffer.
1708 Addr M5_VAR_USED blk_addr = blockAlign(pkt->getAddr());
1709 std::vector<MSHR *> M5_VAR_USED wbs;
1710 assert (!writeBuffer.findMatches(blk_addr, is_secure, wbs));
1711
1712 if (blk == NULL) {
1713 // better have read new data...
1714 assert(pkt->hasData());
1715
1716 // only read responses and write-line requests have data;
1717 // note that we don't write the data here for write-line - that
1718 // happens in the subsequent satisfyCpuSideRequest.
1719 assert(pkt->isRead() || pkt->cmd == MemCmd::WriteLineReq);
1720
1721 // need to do a replacement if allocating, otherwise we stick
1722 // with the temporary storage
1723 blk = allocate ? allocateBlock(addr, is_secure, writebacks) : NULL;
1724
1725 if (blk == NULL) {
1726 // No replaceable block or a mostly exclusive
1727 // cache... just use temporary storage to complete the
1728 // current request and then get rid of it
1729 assert(!tempBlock->isValid());
1730 blk = tempBlock;
1731 tempBlock->set = tags->extractSet(addr);
1732 tempBlock->tag = tags->extractTag(addr);
1733 // @todo: set security state as well...
1734 DPRINTF(Cache, "using temp block for %#llx (%s)\n", addr,
1735 is_secure ? "s" : "ns");
1736 } else {
1737 tags->insertBlock(pkt, blk);
1738 }
1739
1740 // we should never be overwriting a valid block
1741 assert(!blk->isValid());
1742 } else {
1743 // existing block... probably an upgrade
1744 assert(blk->tag == tags->extractTag(addr));
1745 // either we're getting new data or the block should already be valid
1746 assert(pkt->hasData() || blk->isValid());
1747 // don't clear block status... if block is already dirty we
1748 // don't want to lose that
1749 }
1750
1751 if (is_secure)
1752 blk->status |= BlkSecure;
1753 blk->status |= BlkValid | BlkReadable;
1754
1755 // sanity check for whole-line writes, which should always be
1756 // marked as writable as part of the fill, and then later marked
1757 // dirty as part of satisfyCpuSideRequest
1758 if (pkt->cmd == MemCmd::WriteLineReq) {
1759 assert(!pkt->sharedAsserted());
1760 // at the moment other caches do not respond to the
1761 // invalidation requests corresponding to a whole-line write
1762 assert(!pkt->memInhibitAsserted());
1763 }
1764
1765 if (!pkt->sharedAsserted()) {
1766 // we could get non-shared responses from memory (rather than
1767 // a cache) even in a read-only cache, note that we set this
1768 // bit even for a read-only cache as we use it to represent
1769 // the exclusive state
1770 blk->status |= BlkWritable;
1771
1772 // If we got this via cache-to-cache transfer (i.e., from a
1773 // cache that was an owner) and took away that owner's copy,
1774 // then we need to write it back. Normally this happens
1775 // anyway as a side effect of getting a copy to write it, but
1776 // there are cases (such as failed store conditionals or
1777 // compare-and-swaps) where we'll demand an exclusive copy but
1778 // end up not writing it.
1779 if (pkt->memInhibitAsserted()) {
1780 blk->status |= BlkDirty;
1781
1782 chatty_assert(!isReadOnly, "Should never see dirty snoop response "
1783 "in read-only cache %s\n", name());
1784 }
1785 }
1786
1787 DPRINTF(Cache, "Block addr %#llx (%s) moving from state %x to %s\n",
1788 addr, is_secure ? "s" : "ns", old_state, blk->print());
1789
1790 // if we got new data, copy it in (checking for a read response
1791 // and a response that has data is the same in the end)
1792 if (pkt->isRead()) {
1793 // sanity checks
1794 assert(pkt->hasData());
1795 assert(pkt->getSize() == blkSize);
1796
1797 std::memcpy(blk->data, pkt->getConstPtr<uint8_t>(), blkSize);
1798 }
1799 // We pay for fillLatency here.
1800 blk->whenReady = clockEdge() + fillLatency * clockPeriod() +
1801 pkt->payloadDelay;
1802
1803 return blk;
1804}
1805
1806
1807/////////////////////////////////////////////////////
1808//
1809// Snoop path: requests coming in from the memory side
1810//
1811/////////////////////////////////////////////////////
1812
1813void
1814Cache::doTimingSupplyResponse(PacketPtr req_pkt, const uint8_t *blk_data,
1815 bool already_copied, bool pending_inval)
1816{
1817 // sanity check
1818 assert(req_pkt->isRequest());
1819 assert(req_pkt->needsResponse());
1820
1821 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
1822 req_pkt->cmdString(), req_pkt->getAddr(), req_pkt->getSize());
1823 // timing-mode snoop responses require a new packet, unless we
1824 // already made a copy...
1825 PacketPtr pkt = req_pkt;
1826 if (!already_copied)
1827 // do not clear flags, and allocate space for data if the
1828 // packet needs it (the only packets that carry data are read
1829 // responses)
1830 pkt = new Packet(req_pkt, false, req_pkt->isRead());
1831
1832 assert(req_pkt->req->isUncacheable() || req_pkt->isInvalidate() ||
1833 pkt->sharedAsserted());
1834 pkt->makeTimingResponse();
1835 if (pkt->isRead()) {
1836 pkt->setDataFromBlock(blk_data, blkSize);
1837 }
1838 if (pkt->cmd == MemCmd::ReadResp && pending_inval) {
1839 // Assume we defer a response to a read from a far-away cache
1840 // A, then later defer a ReadExcl from a cache B on the same
1841 // bus as us. We'll assert MemInhibit in both cases, but in
1842 // the latter case MemInhibit will keep the invalidation from
1843 // reaching cache A. This special response tells cache A that
1844 // it gets the block to satisfy its read, but must immediately
1845 // invalidate it.
1846 pkt->cmd = MemCmd::ReadRespWithInvalidate;
1847 }
1848 // Here we consider forward_time, paying for just forward latency and
1849 // also charging the delay provided by the xbar.
1850 // forward_time is used as send_time in next allocateWriteBuffer().
1851 Tick forward_time = clockEdge(forwardLatency) + pkt->headerDelay;
1852 // Here we reset the timing of the packet.
1853 pkt->headerDelay = pkt->payloadDelay = 0;
1854 DPRINTF(Cache, "%s created response: %s addr %#llx size %d tick: %lu\n",
1855 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize(),
1856 forward_time);
1857 memSidePort->schedTimingSnoopResp(pkt, forward_time, true);
1858}
1859
1860uint32_t
1861Cache::handleSnoop(PacketPtr pkt, CacheBlk *blk, bool is_timing,
1862 bool is_deferred, bool pending_inval)
1863{
1864 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
1865 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
1866 // deferred snoops can only happen in timing mode
1867 assert(!(is_deferred && !is_timing));
1868 // pending_inval only makes sense on deferred snoops
1869 assert(!(pending_inval && !is_deferred));
1870 assert(pkt->isRequest());
1871
1872 // the packet may get modified if we or a forwarded snooper
1873 // responds in atomic mode, so remember a few things about the
1874 // original packet up front
1875 bool invalidate = pkt->isInvalidate();
1876 bool M5_VAR_USED needs_exclusive = pkt->needsExclusive();
1877
1878 uint32_t snoop_delay = 0;
1879
1880 if (forwardSnoops) {
1881 // first propagate snoop upward to see if anyone above us wants to
1882 // handle it. save & restore packet src since it will get
1883 // rewritten to be relative to cpu-side bus (if any)
1884 bool alreadyResponded = pkt->memInhibitAsserted();
1885 if (is_timing) {
1886 // copy the packet so that we can clear any flags before
1887 // forwarding it upwards, we also allocate data (passing
1888 // the pointer along in case of static data), in case
1889 // there is a snoop hit in upper levels
1890 Packet snoopPkt(pkt, true, true);
1891 snoopPkt.setExpressSnoop();
|
1900 snoopPkt.pushSenderState(new ForwardResponseRecord());
| |
1901 // the snoop packet does not need to wait any additional
1902 // time
1903 snoopPkt.headerDelay = snoopPkt.payloadDelay = 0;
1904 cpuSidePort->sendTimingSnoopReq(&snoopPkt);
1905
1906 // add the header delay (including crossbar and snoop
1907 // delays) of the upward snoop to the snoop delay for this
1908 // cache
1909 snoop_delay += snoopPkt.headerDelay;
1910
1911 if (snoopPkt.memInhibitAsserted()) {
1912 // cache-to-cache response from some upper cache
1913 assert(!alreadyResponded);
1914 pkt->assertMemInhibit();
| 1892 // the snoop packet does not need to wait any additional
1893 // time
1894 snoopPkt.headerDelay = snoopPkt.payloadDelay = 0;
1895 cpuSidePort->sendTimingSnoopReq(&snoopPkt);
1896
1897 // add the header delay (including crossbar and snoop
1898 // delays) of the upward snoop to the snoop delay for this
1899 // cache
1900 snoop_delay += snoopPkt.headerDelay;
1901
1902 if (snoopPkt.memInhibitAsserted()) {
1903 // cache-to-cache response from some upper cache
1904 assert(!alreadyResponded);
1905 pkt->assertMemInhibit();
|
1915 } else {
1916 // no cache (or anyone else for that matter) will
1917 // respond, so delete the ForwardResponseRecord here
1918 delete snoopPkt.popSenderState();
| |
1919 }
1920 if (snoopPkt.sharedAsserted()) {
1921 pkt->assertShared();
1922 }
1923 // If this request is a prefetch or clean evict and an upper level
1924 // signals block present, make sure to propagate the block
1925 // presence to the requester.
1926 if (snoopPkt.isBlockCached()) {
1927 pkt->setBlockCached();
1928 }
1929 } else {
1930 cpuSidePort->sendAtomicSnoop(pkt);
1931 if (!alreadyResponded && pkt->memInhibitAsserted()) {
1932 // cache-to-cache response from some upper cache:
1933 // forward response to original requester
1934 assert(pkt->isResponse());
1935 }
1936 }
1937 }
1938
1939 if (!blk || !blk->isValid()) {
1940 DPRINTF(Cache, "%s snoop miss for %s addr %#llx size %d\n",
1941 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
1942 return snoop_delay;
1943 } else {
1944 DPRINTF(Cache, "%s snoop hit for %s for addr %#llx size %d, "
1945 "old state is %s\n", __func__, pkt->cmdString(),
1946 pkt->getAddr(), pkt->getSize(), blk->print());
1947 }
1948
1949 chatty_assert(!(isReadOnly && blk->isDirty()),
1950 "Should never have a dirty block in a read-only cache %s\n",
1951 name());
1952
1953 // We may end up modifying both the block state and the packet (if
1954 // we respond in atomic mode), so just figure out what to do now
1955 // and then do it later. If we find dirty data while snooping for
1956 // an invalidate, we don't need to send a response. The
1957 // invalidation itself is taken care of below.
1958 bool respond = blk->isDirty() && pkt->needsResponse() &&
1959 pkt->cmd != MemCmd::InvalidateReq;
1960 bool have_exclusive = blk->isWritable();
1961
1962 // Invalidate any prefetch's from below that would strip write permissions
1963 // MemCmd::HardPFReq is only observed by upstream caches. After missing
1964 // above and in it's own cache, a new MemCmd::ReadReq is created that
1965 // downstream caches observe.
1966 if (pkt->mustCheckAbove()) {
1967 DPRINTF(Cache, "Found addr %#llx in upper level cache for snoop %s from"
1968 " lower cache\n", pkt->getAddr(), pkt->cmdString());
1969 pkt->setBlockCached();
1970 return snoop_delay;
1971 }
1972
1973 if (!pkt->req->isUncacheable() && pkt->isRead() && !invalidate) {
1974 // reading non-exclusive shared data, note that we retain
1975 // the block in owned state if it is dirty, with the response
1976 // taken care of below, and otherwhise simply downgrade to
1977 // shared
1978 assert(!needs_exclusive);
1979 pkt->assertShared();
1980 blk->status &= ~BlkWritable;
1981 }
1982
1983 if (respond) {
1984 // prevent anyone else from responding, cache as well as
1985 // memory, and also prevent any memory from even seeing the
1986 // request (with current inhibited semantics), note that this
1987 // applies both to reads and writes and that for writes it
1988 // works thanks to the fact that we still have dirty data and
1989 // will write it back at a later point
1990 assert(!pkt->memInhibitAsserted());
1991 pkt->assertMemInhibit();
1992 if (have_exclusive) {
1993 // in the case of an uncacheable request there is no point
1994 // in setting the exclusive flag, but since the recipient
1995 // does not care there is no harm in doing so, in any case
1996 // it is just a hint
1997 pkt->setSupplyExclusive();
1998 }
1999 if (is_timing) {
2000 doTimingSupplyResponse(pkt, blk->data, is_deferred, pending_inval);
2001 } else {
2002 pkt->makeAtomicResponse();
2003 pkt->setDataFromBlock(blk->data, blkSize);
2004 }
2005 }
2006
2007 if (!respond && is_timing && is_deferred) {
2008 // if it's a deferred timing snoop to which we are not
2009 // responding, then we've made a copy of both the request and
2010 // the packet, delete them here
2011 assert(pkt->needsResponse());
2012 delete pkt->req;
2013 delete pkt;
2014 }
2015
2016 // Do this last in case it deallocates block data or something
2017 // like that
2018 if (invalidate) {
2019 invalidateBlock(blk);
2020 }
2021
2022 DPRINTF(Cache, "new state is %s\n", blk->print());
2023
2024 return snoop_delay;
2025}
2026
2027
2028void
2029Cache::recvTimingSnoopReq(PacketPtr pkt)
2030{
2031 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
2032 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
2033
2034 // Snoops shouldn't happen when bypassing caches
2035 assert(!system->bypassCaches());
2036
2037 // no need to snoop requests that are not in range
2038 if (!inRange(pkt->getAddr())) {
2039 return;
2040 }
2041
2042 bool is_secure = pkt->isSecure();
2043 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
2044
2045 Addr blk_addr = blockAlign(pkt->getAddr());
2046 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
2047
2048 // Update the latency cost of the snoop so that the crossbar can
2049 // account for it. Do not overwrite what other neighbouring caches
2050 // have already done, rather take the maximum. The update is
2051 // tentative, for cases where we return before an upward snoop
2052 // happens below.
2053 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay,
2054 lookupLatency * clockPeriod());
2055
2056 // Inform request(Prefetch, CleanEvict or Writeback) from below of
2057 // MSHR hit, set setBlockCached.
2058 if (mshr && pkt->mustCheckAbove()) {
2059 DPRINTF(Cache, "Setting block cached for %s from"
2060 "lower cache on mshr hit %#x\n",
2061 pkt->cmdString(), pkt->getAddr());
2062 pkt->setBlockCached();
2063 return;
2064 }
2065
2066 // Let the MSHR itself track the snoop and decide whether we want
2067 // to go ahead and do the regular cache snoop
2068 if (mshr && mshr->handleSnoop(pkt, order++)) {
2069 DPRINTF(Cache, "Deferring snoop on in-service MSHR to blk %#llx (%s)."
2070 "mshrs: %s\n", blk_addr, is_secure ? "s" : "ns",
2071 mshr->print());
2072
2073 if (mshr->getNumTargets() > numTarget)
2074 warn("allocating bonus target for snoop"); //handle later
2075 return;
2076 }
2077
2078 //We also need to check the writeback buffers and handle those
2079 std::vector<MSHR *> writebacks;
2080 if (writeBuffer.findMatches(blk_addr, is_secure, writebacks)) {
2081 DPRINTF(Cache, "Snoop hit in writeback to addr %#llx (%s)\n",
2082 pkt->getAddr(), is_secure ? "s" : "ns");
2083
2084 // Look through writebacks for any cachable writes.
2085 // We should only ever find a single match
2086 assert(writebacks.size() == 1);
2087 MSHR *wb_entry = writebacks[0];
2088 // Expect to see only Writebacks and/or CleanEvicts here, both of
2089 // which should not be generated for uncacheable data.
2090 assert(!wb_entry->isUncacheable());
2091 // There should only be a single request responsible for generating
2092 // Writebacks/CleanEvicts.
2093 assert(wb_entry->getNumTargets() == 1);
2094 PacketPtr wb_pkt = wb_entry->getTarget()->pkt;
2095 assert(wb_pkt->isEviction());
2096
2097 if (pkt->isEviction()) {
2098 // if the block is found in the write queue, set the BLOCK_CACHED
2099 // flag for Writeback/CleanEvict snoop. On return the snoop will
2100 // propagate the BLOCK_CACHED flag in Writeback packets and prevent
2101 // any CleanEvicts from travelling down the memory hierarchy.
2102 pkt->setBlockCached();
2103 DPRINTF(Cache, "Squashing %s from lower cache on writequeue hit"
2104 " %#x\n", pkt->cmdString(), pkt->getAddr());
2105 return;
2106 }
2107
2108 if (wb_pkt->cmd == MemCmd::WritebackDirty) {
2109 assert(!pkt->memInhibitAsserted());
2110 pkt->assertMemInhibit();
2111 if (!pkt->needsExclusive()) {
2112 pkt->assertShared();
2113 // the writeback is no longer passing exclusivity (the
2114 // receiving cache should consider the block owned
2115 // rather than modified)
2116 wb_pkt->assertShared();
2117 } else {
2118 // if we're not asserting the shared line, we need to
2119 // invalidate our copy. we'll do that below as long as
2120 // the packet's invalidate flag is set...
2121 assert(pkt->isInvalidate());
2122 }
2123 doTimingSupplyResponse(pkt, wb_pkt->getConstPtr<uint8_t>(),
2124 false, false);
2125 } else {
2126 // on hitting a clean writeback we play it safe and do not
2127 // provide a response, the block may be dirty somewhere
2128 // else
2129 assert(wb_pkt->isCleanEviction());
2130 // The cache technically holds the block until the
2131 // corresponding message reaches the crossbar
2132 // below. Therefore when a snoop encounters a CleanEvict
2133 // or WritebackClean message we must set assertShared
2134 // (just like when it encounters a Writeback) to avoid the
2135 // snoop filter prematurely clearing the holder bit in the
2136 // crossbar below
2137 if (!pkt->needsExclusive()) {
2138 pkt->assertShared();
2139 // the writeback is no longer passing exclusivity (the
2140 // receiving cache should consider the block owned
2141 // rather than modified)
2142 wb_pkt->assertShared();
2143 } else {
2144 assert(pkt->isInvalidate());
2145 }
2146 }
2147
2148 if (pkt->isInvalidate()) {
2149 // Invalidation trumps our writeback... discard here
2150 // Note: markInService will remove entry from writeback buffer.
2151 markInService(wb_entry, false);
2152 delete wb_pkt;
2153 }
2154 }
2155
2156 // If this was a shared writeback, there may still be
2157 // other shared copies above that require invalidation.
2158 // We could be more selective and return here if the
2159 // request is non-exclusive or if the writeback is
2160 // exclusive.
2161 uint32_t snoop_delay = handleSnoop(pkt, blk, true, false, false);
2162
2163 // Override what we did when we first saw the snoop, as we now
2164 // also have the cost of the upwards snoops to account for
2165 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, snoop_delay +
2166 lookupLatency * clockPeriod());
2167}
2168
2169bool
2170Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt)
2171{
2172 // Express snoop responses from master to slave, e.g., from L1 to L2
2173 cache->recvTimingSnoopResp(pkt);
2174 return true;
2175}
2176
2177Tick
2178Cache::recvAtomicSnoop(PacketPtr pkt)
2179{
2180 // Snoops shouldn't happen when bypassing caches
2181 assert(!system->bypassCaches());
2182
2183 // no need to snoop requests that are not in range.
2184 if (!inRange(pkt->getAddr())) {
2185 return 0;
2186 }
2187
2188 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
2189 uint32_t snoop_delay = handleSnoop(pkt, blk, false, false, false);
2190 return snoop_delay + lookupLatency * clockPeriod();
2191}
2192
2193
2194MSHR *
2195Cache::getNextMSHR()
2196{
2197 // Check both MSHR queue and write buffer for potential requests,
2198 // note that null does not mean there is no request, it could
2199 // simply be that it is not ready
2200 MSHR *miss_mshr = mshrQueue.getNextMSHR();
2201 MSHR *write_mshr = writeBuffer.getNextMSHR();
2202
2203 // If we got a write buffer request ready, first priority is a
2204 // full write buffer, otherwhise we favour the miss requests
2205 if (write_mshr &&
2206 ((writeBuffer.isFull() && writeBuffer.inServiceEntries == 0) ||
2207 !miss_mshr)) {
2208 // need to search MSHR queue for conflicting earlier miss.
2209 MSHR *conflict_mshr =
2210 mshrQueue.findPending(write_mshr->blkAddr,
2211 write_mshr->isSecure);
2212
2213 if (conflict_mshr && conflict_mshr->order < write_mshr->order) {
2214 // Service misses in order until conflict is cleared.
2215 return conflict_mshr;
2216
2217 // @todo Note that we ignore the ready time of the conflict here
2218 }
2219
2220 // No conflicts; issue write
2221 return write_mshr;
2222 } else if (miss_mshr) {
2223 // need to check for conflicting earlier writeback
2224 MSHR *conflict_mshr =
2225 writeBuffer.findPending(miss_mshr->blkAddr,
2226 miss_mshr->isSecure);
2227 if (conflict_mshr) {
2228 // not sure why we don't check order here... it was in the
2229 // original code but commented out.
2230
2231 // The only way this happens is if we are
2232 // doing a write and we didn't have permissions
2233 // then subsequently saw a writeback (owned got evicted)
2234 // We need to make sure to perform the writeback first
2235 // To preserve the dirty data, then we can issue the write
2236
2237 // should we return write_mshr here instead? I.e. do we
2238 // have to flush writes in order? I don't think so... not
2239 // for Alpha anyway. Maybe for x86?
2240 return conflict_mshr;
2241
2242 // @todo Note that we ignore the ready time of the conflict here
2243 }
2244
2245 // No conflicts; issue read
2246 return miss_mshr;
2247 }
2248
2249 // fall through... no pending requests. Try a prefetch.
2250 assert(!miss_mshr && !write_mshr);
2251 if (prefetcher && mshrQueue.canPrefetch()) {
2252 // If we have a miss queue slot, we can try a prefetch
2253 PacketPtr pkt = prefetcher->getPacket();
2254 if (pkt) {
2255 Addr pf_addr = blockAlign(pkt->getAddr());
2256 if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
2257 !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
2258 !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
2259 // Update statistic on number of prefetches issued
2260 // (hwpf_mshr_misses)
2261 assert(pkt->req->masterId() < system->maxMasters());
2262 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
2263
2264 // allocate an MSHR and return it, note
2265 // that we send the packet straight away, so do not
2266 // schedule the send
2267 return allocateMissBuffer(pkt, curTick(), false);
2268 } else {
2269 // free the request and packet
2270 delete pkt->req;
2271 delete pkt;
2272 }
2273 }
2274 }
2275
2276 return NULL;
2277}
2278
2279bool
2280Cache::isCachedAbove(PacketPtr pkt, bool is_timing) const
2281{
2282 if (!forwardSnoops)
2283 return false;
2284 // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and
2285 // Writeback snoops into upper level caches to check for copies of the
2286 // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict
2287 // packet, the cache can inform the crossbar below of presence or absence
2288 // of the block.
2289 if (is_timing) {
2290 Packet snoop_pkt(pkt, true, false);
2291 snoop_pkt.setExpressSnoop();
2292 // Assert that packet is either Writeback or CleanEvict and not a
2293 // prefetch request because prefetch requests need an MSHR and may
2294 // generate a snoop response.
2295 assert(pkt->isEviction());
2296 snoop_pkt.senderState = NULL;
2297 cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
2298 // Writeback/CleanEvict snoops do not generate a snoop response.
2299 assert(!(snoop_pkt.memInhibitAsserted()));
2300 return snoop_pkt.isBlockCached();
2301 } else {
2302 cpuSidePort->sendAtomicSnoop(pkt);
2303 return pkt->isBlockCached();
2304 }
2305}
2306
2307PacketPtr
2308Cache::getTimingPacket()
2309{
2310 MSHR *mshr = getNextMSHR();
2311
2312 if (mshr == NULL) {
2313 return NULL;
2314 }
2315
2316 // use request from 1st target
2317 PacketPtr tgt_pkt = mshr->getTarget()->pkt;
2318 PacketPtr pkt = NULL;
2319
2320 DPRINTF(CachePort, "%s %s for addr %#llx size %d\n", __func__,
2321 tgt_pkt->cmdString(), tgt_pkt->getAddr(), tgt_pkt->getSize());
2322
2323 CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
2324
2325 if (tgt_pkt->cmd == MemCmd::HardPFReq && forwardSnoops) {
2326 // We need to check the caches above us to verify that
2327 // they don't have a copy of this block in the dirty state
2328 // at the moment. Without this check we could get a stale
2329 // copy from memory that might get used in place of the
2330 // dirty one.
2331 Packet snoop_pkt(tgt_pkt, true, false);
2332 snoop_pkt.setExpressSnoop();
2333 // We are sending this packet upwards, but if it hits we will
2334 // get a snoop response that we end up treating just like a
2335 // normal response, hence it needs the MSHR as its sender
2336 // state
2337 snoop_pkt.senderState = mshr;
2338 cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
2339
2340 // Check to see if the prefetch was squashed by an upper cache (to
2341 // prevent us from grabbing the line) or if a Check to see if a
2342 // writeback arrived between the time the prefetch was placed in
2343 // the MSHRs and when it was selected to be sent or if the
2344 // prefetch was squashed by an upper cache.
2345
2346 // It is important to check memInhibitAsserted before
2347 // prefetchSquashed. If another cache has asserted MEM_INGIBIT, it
2348 // will be sending a response which will arrive at the MSHR
2349 // allocated ofr this request. Checking the prefetchSquash first
2350 // may result in the MSHR being prematurely deallocated.
2351
2352 if (snoop_pkt.memInhibitAsserted()) {
| 1906 }
1907 if (snoopPkt.sharedAsserted()) {
1908 pkt->assertShared();
1909 }
1910 // If this request is a prefetch or clean evict and an upper level
1911 // signals block present, make sure to propagate the block
1912 // presence to the requester.
1913 if (snoopPkt.isBlockCached()) {
1914 pkt->setBlockCached();
1915 }
1916 } else {
1917 cpuSidePort->sendAtomicSnoop(pkt);
1918 if (!alreadyResponded && pkt->memInhibitAsserted()) {
1919 // cache-to-cache response from some upper cache:
1920 // forward response to original requester
1921 assert(pkt->isResponse());
1922 }
1923 }
1924 }
1925
1926 if (!blk || !blk->isValid()) {
1927 DPRINTF(Cache, "%s snoop miss for %s addr %#llx size %d\n",
1928 __func__, pkt->cmdString(), pkt->getAddr(), pkt->getSize());
1929 return snoop_delay;
1930 } else {
1931 DPRINTF(Cache, "%s snoop hit for %s for addr %#llx size %d, "
1932 "old state is %s\n", __func__, pkt->cmdString(),
1933 pkt->getAddr(), pkt->getSize(), blk->print());
1934 }
1935
1936 chatty_assert(!(isReadOnly && blk->isDirty()),
1937 "Should never have a dirty block in a read-only cache %s\n",
1938 name());
1939
1940 // We may end up modifying both the block state and the packet (if
1941 // we respond in atomic mode), so just figure out what to do now
1942 // and then do it later. If we find dirty data while snooping for
1943 // an invalidate, we don't need to send a response. The
1944 // invalidation itself is taken care of below.
1945 bool respond = blk->isDirty() && pkt->needsResponse() &&
1946 pkt->cmd != MemCmd::InvalidateReq;
1947 bool have_exclusive = blk->isWritable();
1948
1949 // Invalidate any prefetch's from below that would strip write permissions
1950 // MemCmd::HardPFReq is only observed by upstream caches. After missing
1951 // above and in it's own cache, a new MemCmd::ReadReq is created that
1952 // downstream caches observe.
1953 if (pkt->mustCheckAbove()) {
1954 DPRINTF(Cache, "Found addr %#llx in upper level cache for snoop %s from"
1955 " lower cache\n", pkt->getAddr(), pkt->cmdString());
1956 pkt->setBlockCached();
1957 return snoop_delay;
1958 }
1959
1960 if (!pkt->req->isUncacheable() && pkt->isRead() && !invalidate) {
1961 // reading non-exclusive shared data, note that we retain
1962 // the block in owned state if it is dirty, with the response
1963 // taken care of below, and otherwhise simply downgrade to
1964 // shared
1965 assert(!needs_exclusive);
1966 pkt->assertShared();
1967 blk->status &= ~BlkWritable;
1968 }
1969
1970 if (respond) {
1971 // prevent anyone else from responding, cache as well as
1972 // memory, and also prevent any memory from even seeing the
1973 // request (with current inhibited semantics), note that this
1974 // applies both to reads and writes and that for writes it
1975 // works thanks to the fact that we still have dirty data and
1976 // will write it back at a later point
1977 assert(!pkt->memInhibitAsserted());
1978 pkt->assertMemInhibit();
1979 if (have_exclusive) {
1980 // in the case of an uncacheable request there is no point
1981 // in setting the exclusive flag, but since the recipient
1982 // does not care there is no harm in doing so, in any case
1983 // it is just a hint
1984 pkt->setSupplyExclusive();
1985 }
1986 if (is_timing) {
1987 doTimingSupplyResponse(pkt, blk->data, is_deferred, pending_inval);
1988 } else {
1989 pkt->makeAtomicResponse();
1990 pkt->setDataFromBlock(blk->data, blkSize);
1991 }
1992 }
1993
1994 if (!respond && is_timing && is_deferred) {
1995 // if it's a deferred timing snoop to which we are not
1996 // responding, then we've made a copy of both the request and
1997 // the packet, delete them here
1998 assert(pkt->needsResponse());
1999 delete pkt->req;
2000 delete pkt;
2001 }
2002
2003 // Do this last in case it deallocates block data or something
2004 // like that
2005 if (invalidate) {
2006 invalidateBlock(blk);
2007 }
2008
2009 DPRINTF(Cache, "new state is %s\n", blk->print());
2010
2011 return snoop_delay;
2012}
2013
2014
2015void
2016Cache::recvTimingSnoopReq(PacketPtr pkt)
2017{
2018 DPRINTF(Cache, "%s for %s addr %#llx size %d\n", __func__,
2019 pkt->cmdString(), pkt->getAddr(), pkt->getSize());
2020
2021 // Snoops shouldn't happen when bypassing caches
2022 assert(!system->bypassCaches());
2023
2024 // no need to snoop requests that are not in range
2025 if (!inRange(pkt->getAddr())) {
2026 return;
2027 }
2028
2029 bool is_secure = pkt->isSecure();
2030 CacheBlk *blk = tags->findBlock(pkt->getAddr(), is_secure);
2031
2032 Addr blk_addr = blockAlign(pkt->getAddr());
2033 MSHR *mshr = mshrQueue.findMatch(blk_addr, is_secure);
2034
2035 // Update the latency cost of the snoop so that the crossbar can
2036 // account for it. Do not overwrite what other neighbouring caches
2037 // have already done, rather take the maximum. The update is
2038 // tentative, for cases where we return before an upward snoop
2039 // happens below.
2040 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay,
2041 lookupLatency * clockPeriod());
2042
2043 // Inform request(Prefetch, CleanEvict or Writeback) from below of
2044 // MSHR hit, set setBlockCached.
2045 if (mshr && pkt->mustCheckAbove()) {
2046 DPRINTF(Cache, "Setting block cached for %s from"
2047 "lower cache on mshr hit %#x\n",
2048 pkt->cmdString(), pkt->getAddr());
2049 pkt->setBlockCached();
2050 return;
2051 }
2052
2053 // Let the MSHR itself track the snoop and decide whether we want
2054 // to go ahead and do the regular cache snoop
2055 if (mshr && mshr->handleSnoop(pkt, order++)) {
2056 DPRINTF(Cache, "Deferring snoop on in-service MSHR to blk %#llx (%s)."
2057 "mshrs: %s\n", blk_addr, is_secure ? "s" : "ns",
2058 mshr->print());
2059
2060 if (mshr->getNumTargets() > numTarget)
2061 warn("allocating bonus target for snoop"); //handle later
2062 return;
2063 }
2064
2065 //We also need to check the writeback buffers and handle those
2066 std::vector<MSHR *> writebacks;
2067 if (writeBuffer.findMatches(blk_addr, is_secure, writebacks)) {
2068 DPRINTF(Cache, "Snoop hit in writeback to addr %#llx (%s)\n",
2069 pkt->getAddr(), is_secure ? "s" : "ns");
2070
2071 // Look through writebacks for any cachable writes.
2072 // We should only ever find a single match
2073 assert(writebacks.size() == 1);
2074 MSHR *wb_entry = writebacks[0];
2075 // Expect to see only Writebacks and/or CleanEvicts here, both of
2076 // which should not be generated for uncacheable data.
2077 assert(!wb_entry->isUncacheable());
2078 // There should only be a single request responsible for generating
2079 // Writebacks/CleanEvicts.
2080 assert(wb_entry->getNumTargets() == 1);
2081 PacketPtr wb_pkt = wb_entry->getTarget()->pkt;
2082 assert(wb_pkt->isEviction());
2083
2084 if (pkt->isEviction()) {
2085 // if the block is found in the write queue, set the BLOCK_CACHED
2086 // flag for Writeback/CleanEvict snoop. On return the snoop will
2087 // propagate the BLOCK_CACHED flag in Writeback packets and prevent
2088 // any CleanEvicts from travelling down the memory hierarchy.
2089 pkt->setBlockCached();
2090 DPRINTF(Cache, "Squashing %s from lower cache on writequeue hit"
2091 " %#x\n", pkt->cmdString(), pkt->getAddr());
2092 return;
2093 }
2094
2095 if (wb_pkt->cmd == MemCmd::WritebackDirty) {
2096 assert(!pkt->memInhibitAsserted());
2097 pkt->assertMemInhibit();
2098 if (!pkt->needsExclusive()) {
2099 pkt->assertShared();
2100 // the writeback is no longer passing exclusivity (the
2101 // receiving cache should consider the block owned
2102 // rather than modified)
2103 wb_pkt->assertShared();
2104 } else {
2105 // if we're not asserting the shared line, we need to
2106 // invalidate our copy. we'll do that below as long as
2107 // the packet's invalidate flag is set...
2108 assert(pkt->isInvalidate());
2109 }
2110 doTimingSupplyResponse(pkt, wb_pkt->getConstPtr<uint8_t>(),
2111 false, false);
2112 } else {
2113 // on hitting a clean writeback we play it safe and do not
2114 // provide a response, the block may be dirty somewhere
2115 // else
2116 assert(wb_pkt->isCleanEviction());
2117 // The cache technically holds the block until the
2118 // corresponding message reaches the crossbar
2119 // below. Therefore when a snoop encounters a CleanEvict
2120 // or WritebackClean message we must set assertShared
2121 // (just like when it encounters a Writeback) to avoid the
2122 // snoop filter prematurely clearing the holder bit in the
2123 // crossbar below
2124 if (!pkt->needsExclusive()) {
2125 pkt->assertShared();
2126 // the writeback is no longer passing exclusivity (the
2127 // receiving cache should consider the block owned
2128 // rather than modified)
2129 wb_pkt->assertShared();
2130 } else {
2131 assert(pkt->isInvalidate());
2132 }
2133 }
2134
2135 if (pkt->isInvalidate()) {
2136 // Invalidation trumps our writeback... discard here
2137 // Note: markInService will remove entry from writeback buffer.
2138 markInService(wb_entry, false);
2139 delete wb_pkt;
2140 }
2141 }
2142
2143 // If this was a shared writeback, there may still be
2144 // other shared copies above that require invalidation.
2145 // We could be more selective and return here if the
2146 // request is non-exclusive or if the writeback is
2147 // exclusive.
2148 uint32_t snoop_delay = handleSnoop(pkt, blk, true, false, false);
2149
2150 // Override what we did when we first saw the snoop, as we now
2151 // also have the cost of the upwards snoops to account for
2152 pkt->snoopDelay = std::max<uint32_t>(pkt->snoopDelay, snoop_delay +
2153 lookupLatency * clockPeriod());
2154}
2155
2156bool
2157Cache::CpuSidePort::recvTimingSnoopResp(PacketPtr pkt)
2158{
2159 // Express snoop responses from master to slave, e.g., from L1 to L2
2160 cache->recvTimingSnoopResp(pkt);
2161 return true;
2162}
2163
2164Tick
2165Cache::recvAtomicSnoop(PacketPtr pkt)
2166{
2167 // Snoops shouldn't happen when bypassing caches
2168 assert(!system->bypassCaches());
2169
2170 // no need to snoop requests that are not in range.
2171 if (!inRange(pkt->getAddr())) {
2172 return 0;
2173 }
2174
2175 CacheBlk *blk = tags->findBlock(pkt->getAddr(), pkt->isSecure());
2176 uint32_t snoop_delay = handleSnoop(pkt, blk, false, false, false);
2177 return snoop_delay + lookupLatency * clockPeriod();
2178}
2179
2180
2181MSHR *
2182Cache::getNextMSHR()
2183{
2184 // Check both MSHR queue and write buffer for potential requests,
2185 // note that null does not mean there is no request, it could
2186 // simply be that it is not ready
2187 MSHR *miss_mshr = mshrQueue.getNextMSHR();
2188 MSHR *write_mshr = writeBuffer.getNextMSHR();
2189
2190 // If we got a write buffer request ready, first priority is a
2191 // full write buffer, otherwhise we favour the miss requests
2192 if (write_mshr &&
2193 ((writeBuffer.isFull() && writeBuffer.inServiceEntries == 0) ||
2194 !miss_mshr)) {
2195 // need to search MSHR queue for conflicting earlier miss.
2196 MSHR *conflict_mshr =
2197 mshrQueue.findPending(write_mshr->blkAddr,
2198 write_mshr->isSecure);
2199
2200 if (conflict_mshr && conflict_mshr->order < write_mshr->order) {
2201 // Service misses in order until conflict is cleared.
2202 return conflict_mshr;
2203
2204 // @todo Note that we ignore the ready time of the conflict here
2205 }
2206
2207 // No conflicts; issue write
2208 return write_mshr;
2209 } else if (miss_mshr) {
2210 // need to check for conflicting earlier writeback
2211 MSHR *conflict_mshr =
2212 writeBuffer.findPending(miss_mshr->blkAddr,
2213 miss_mshr->isSecure);
2214 if (conflict_mshr) {
2215 // not sure why we don't check order here... it was in the
2216 // original code but commented out.
2217
2218 // The only way this happens is if we are
2219 // doing a write and we didn't have permissions
2220 // then subsequently saw a writeback (owned got evicted)
2221 // We need to make sure to perform the writeback first
2222 // To preserve the dirty data, then we can issue the write
2223
2224 // should we return write_mshr here instead? I.e. do we
2225 // have to flush writes in order? I don't think so... not
2226 // for Alpha anyway. Maybe for x86?
2227 return conflict_mshr;
2228
2229 // @todo Note that we ignore the ready time of the conflict here
2230 }
2231
2232 // No conflicts; issue read
2233 return miss_mshr;
2234 }
2235
2236 // fall through... no pending requests. Try a prefetch.
2237 assert(!miss_mshr && !write_mshr);
2238 if (prefetcher && mshrQueue.canPrefetch()) {
2239 // If we have a miss queue slot, we can try a prefetch
2240 PacketPtr pkt = prefetcher->getPacket();
2241 if (pkt) {
2242 Addr pf_addr = blockAlign(pkt->getAddr());
2243 if (!tags->findBlock(pf_addr, pkt->isSecure()) &&
2244 !mshrQueue.findMatch(pf_addr, pkt->isSecure()) &&
2245 !writeBuffer.findMatch(pf_addr, pkt->isSecure())) {
2246 // Update statistic on number of prefetches issued
2247 // (hwpf_mshr_misses)
2248 assert(pkt->req->masterId() < system->maxMasters());
2249 mshr_misses[pkt->cmdToIndex()][pkt->req->masterId()]++;
2250
2251 // allocate an MSHR and return it, note
2252 // that we send the packet straight away, so do not
2253 // schedule the send
2254 return allocateMissBuffer(pkt, curTick(), false);
2255 } else {
2256 // free the request and packet
2257 delete pkt->req;
2258 delete pkt;
2259 }
2260 }
2261 }
2262
2263 return NULL;
2264}
2265
2266bool
2267Cache::isCachedAbove(PacketPtr pkt, bool is_timing) const
2268{
2269 if (!forwardSnoops)
2270 return false;
2271 // Mirroring the flow of HardPFReqs, the cache sends CleanEvict and
2272 // Writeback snoops into upper level caches to check for copies of the
2273 // same block. Using the BLOCK_CACHED flag with the Writeback/CleanEvict
2274 // packet, the cache can inform the crossbar below of presence or absence
2275 // of the block.
2276 if (is_timing) {
2277 Packet snoop_pkt(pkt, true, false);
2278 snoop_pkt.setExpressSnoop();
2279 // Assert that packet is either Writeback or CleanEvict and not a
2280 // prefetch request because prefetch requests need an MSHR and may
2281 // generate a snoop response.
2282 assert(pkt->isEviction());
2283 snoop_pkt.senderState = NULL;
2284 cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
2285 // Writeback/CleanEvict snoops do not generate a snoop response.
2286 assert(!(snoop_pkt.memInhibitAsserted()));
2287 return snoop_pkt.isBlockCached();
2288 } else {
2289 cpuSidePort->sendAtomicSnoop(pkt);
2290 return pkt->isBlockCached();
2291 }
2292}
2293
2294PacketPtr
2295Cache::getTimingPacket()
2296{
2297 MSHR *mshr = getNextMSHR();
2298
2299 if (mshr == NULL) {
2300 return NULL;
2301 }
2302
2303 // use request from 1st target
2304 PacketPtr tgt_pkt = mshr->getTarget()->pkt;
2305 PacketPtr pkt = NULL;
2306
2307 DPRINTF(CachePort, "%s %s for addr %#llx size %d\n", __func__,
2308 tgt_pkt->cmdString(), tgt_pkt->getAddr(), tgt_pkt->getSize());
2309
2310 CacheBlk *blk = tags->findBlock(mshr->blkAddr, mshr->isSecure);
2311
2312 if (tgt_pkt->cmd == MemCmd::HardPFReq && forwardSnoops) {
2313 // We need to check the caches above us to verify that
2314 // they don't have a copy of this block in the dirty state
2315 // at the moment. Without this check we could get a stale
2316 // copy from memory that might get used in place of the
2317 // dirty one.
2318 Packet snoop_pkt(tgt_pkt, true, false);
2319 snoop_pkt.setExpressSnoop();
2320 // We are sending this packet upwards, but if it hits we will
2321 // get a snoop response that we end up treating just like a
2322 // normal response, hence it needs the MSHR as its sender
2323 // state
2324 snoop_pkt.senderState = mshr;
2325 cpuSidePort->sendTimingSnoopReq(&snoop_pkt);
2326
2327 // Check to see if the prefetch was squashed by an upper cache (to
2328 // prevent us from grabbing the line) or if a Check to see if a
2329 // writeback arrived between the time the prefetch was placed in
2330 // the MSHRs and when it was selected to be sent or if the
2331 // prefetch was squashed by an upper cache.
2332
2333 // It is important to check memInhibitAsserted before
2334 // prefetchSquashed. If another cache has asserted MEM_INGIBIT, it
2335 // will be sending a response which will arrive at the MSHR
2336 // allocated ofr this request. Checking the prefetchSquash first
2337 // may result in the MSHR being prematurely deallocated.
2338
2339 if (snoop_pkt.memInhibitAsserted()) {
|
| 2340 auto M5_VAR_USED r = outstandingSnoop.insert(snoop_pkt.req);
2341 assert(r.second);
|
2353 // If we are getting a non-shared response it is dirty
2354 bool pending_dirty_resp = !snoop_pkt.sharedAsserted();
2355 markInService(mshr, pending_dirty_resp);
2356 DPRINTF(Cache, "Upward snoop of prefetch for addr"
2357 " %#x (%s) hit\n",
2358 tgt_pkt->getAddr(), tgt_pkt->isSecure()? "s": "ns");
2359 return NULL;
2360 }
2361
2362 if (snoop_pkt.isBlockCached() || blk != NULL) {
2363 DPRINTF(Cache, "Block present, prefetch squashed by cache. "
2364 "Deallocating mshr target %#x.\n",
2365 mshr->blkAddr);
2366
2367 // Deallocate the mshr target
2368 if (!tgt_pkt->isWriteback()) {
2369 if (mshr->queue->forceDeallocateTarget(mshr)) {
2370 // Clear block if this deallocation resulted freed an
2371 // mshr when all had previously been utilized
2372 clearBlocked((BlockedCause)(mshr->queue->index));
2373 }
2374 return NULL;
2375 } else {
2376 // If this is a Writeback, and the snoops indicate that the blk
2377 // is cached above, set the BLOCK_CACHED flag in the Writeback
2378 // packet, so that it does not reset the bits corresponding to
2379 // this block in the snoop filter below.
2380 tgt_pkt->setBlockCached();
2381 }
2382 }
2383 }
2384
2385 if (mshr->isForwardNoResponse()) {
2386 // no response expected, just forward packet as it is
2387 assert(tags->findBlock(mshr->blkAddr, mshr->isSecure) == NULL);
2388 pkt = tgt_pkt;
2389 } else {
2390 pkt = getBusPacket(tgt_pkt, blk, mshr->needsExclusive());
2391
2392 mshr->isForward = (pkt == NULL);
2393
2394 if (mshr->isForward) {
2395 // not a cache block request, but a response is expected
2396 // make copy of current packet to forward, keep current
2397 // copy for response handling
2398 pkt = new Packet(tgt_pkt, false, true);
2399 if (pkt->isWrite()) {
2400 pkt->setData(tgt_pkt->getConstPtr<uint8_t>());
2401 }
2402 }
2403 }
2404
2405 assert(pkt != NULL);
2406 // play it safe and append (rather than set) the sender state, as
2407 // forwarded packets may already have existing state
2408 pkt->pushSenderState(mshr);
2409 return pkt;
2410}
2411
2412
2413Tick
2414Cache::nextMSHRReadyTime() const
2415{
2416 Tick nextReady = std::min(mshrQueue.nextMSHRReadyTime(),
2417 writeBuffer.nextMSHRReadyTime());
2418
2419 // Don't signal prefetch ready time if no MSHRs available
2420 // Will signal once enoguh MSHRs are deallocated
2421 if (prefetcher && mshrQueue.canPrefetch()) {
2422 nextReady = std::min(nextReady,
2423 prefetcher->nextPrefetchReadyTime());
2424 }
2425
2426 return nextReady;
2427}
2428
2429void
2430Cache::serialize(CheckpointOut &cp) const
2431{
2432 bool dirty(isDirty());
2433
2434 if (dirty) {
2435 warn("*** The cache still contains dirty data. ***\n");
2436 warn(" Make sure to drain the system using the correct flags.\n");
2437 warn(" This checkpoint will not restore correctly and dirty data in "
2438 "the cache will be lost!\n");
2439 }
2440
2441 // Since we don't checkpoint the data in the cache, any dirty data
2442 // will be lost when restoring from a checkpoint of a system that
2443 // wasn't drained properly. Flag the checkpoint as invalid if the
2444 // cache contains dirty data.
2445 bool bad_checkpoint(dirty);
2446 SERIALIZE_SCALAR(bad_checkpoint);
2447}
2448
2449void
2450Cache::unserialize(CheckpointIn &cp)
2451{
2452 bool bad_checkpoint;
2453 UNSERIALIZE_SCALAR(bad_checkpoint);
2454 if (bad_checkpoint) {
2455 fatal("Restoring from checkpoints with dirty caches is not supported "
2456 "in the classic memory system. Please remove any caches or "
2457 " drain them properly before taking checkpoints.\n");
2458 }
2459}
2460
2461///////////////
2462//
2463// CpuSidePort
2464//
2465///////////////
2466
2467AddrRangeList
2468Cache::CpuSidePort::getAddrRanges() const
2469{
2470 return cache->getAddrRanges();
2471}
2472
2473bool
2474Cache::CpuSidePort::recvTimingReq(PacketPtr pkt)
2475{
2476 assert(!cache->system->bypassCaches());
2477
2478 bool success = false;
2479
2480 // always let inhibited requests through, even if blocked,
2481 // ultimately we should check if this is an express snoop, but at
2482 // the moment that flag is only set in the cache itself
2483 if (pkt->memInhibitAsserted()) {
2484 // do not change the current retry state
2485 bool M5_VAR_USED bypass_success = cache->recvTimingReq(pkt);
2486 assert(bypass_success);
2487 return true;
2488 } else if (blocked || mustSendRetry) {
2489 // either already committed to send a retry, or blocked
2490 success = false;
2491 } else {
2492 // pass it on to the cache, and let the cache decide if we
2493 // have to retry or not
2494 success = cache->recvTimingReq(pkt);
2495 }
2496
2497 // remember if we have to retry
2498 mustSendRetry = !success;
2499 return success;
2500}
2501
2502Tick
2503Cache::CpuSidePort::recvAtomic(PacketPtr pkt)
2504{
2505 return cache->recvAtomic(pkt);
2506}
2507
2508void
2509Cache::CpuSidePort::recvFunctional(PacketPtr pkt)
2510{
2511 // functional request
2512 cache->functionalAccess(pkt, true);
2513}
2514
2515Cache::
2516CpuSidePort::CpuSidePort(const std::string &_name, Cache *_cache,
2517 const std::string &_label)
2518 : BaseCache::CacheSlavePort(_name, _cache, _label), cache(_cache)
2519{
2520}
2521
2522Cache*
2523CacheParams::create()
2524{
2525 assert(tags);
2526
2527 return new Cache(this);
2528}
2529///////////////
2530//
2531// MemSidePort
2532//
2533///////////////
2534
2535bool
2536Cache::MemSidePort::recvTimingResp(PacketPtr pkt)
2537{
2538 cache->recvTimingResp(pkt);
2539 return true;
2540}
2541
2542// Express snooping requests to memside port
2543void
2544Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt)
2545{
2546 // handle snooping requests
2547 cache->recvTimingSnoopReq(pkt);
2548}
2549
2550Tick
2551Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt)
2552{
2553 return cache->recvAtomicSnoop(pkt);
2554}
2555
2556void
2557Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt)
2558{
2559 // functional snoop (note that in contrast to atomic we don't have
2560 // a specific functionalSnoop method, as they have the same
2561 // behaviour regardless)
2562 cache->functionalAccess(pkt, false);
2563}
2564
2565void
2566Cache::CacheReqPacketQueue::sendDeferredPacket()
2567{
2568 // sanity check
2569 assert(!waitingOnRetry);
2570
2571 // there should never be any deferred request packets in the
2572 // queue, instead we resly on the cache to provide the packets
2573 // from the MSHR queue or write queue
2574 assert(deferredPacketReadyTime() == MaxTick);
2575
2576 // check for request packets (requests & writebacks)
2577 PacketPtr pkt = cache.getTimingPacket();
2578 if (pkt == NULL) {
2579 // can happen if e.g. we attempt a writeback and fail, but
2580 // before the retry, the writeback is eliminated because
2581 // we snoop another cache's ReadEx.
2582 } else {
2583 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
2584 // in most cases getTimingPacket allocates a new packet, and
2585 // we must delete it unless it is successfully sent
2586 bool delete_pkt = !mshr->isForwardNoResponse();
2587
2588 // let our snoop responses go first if there are responses to
2589 // the same addresses we are about to writeback, note that
2590 // this creates a dependency between requests and snoop
2591 // responses, but that should not be a problem since there is
2592 // a chain already and the key is that the snoop responses can
2593 // sink unconditionally
2594 if (snoopRespQueue.hasAddr(pkt->getAddr())) {
2595 DPRINTF(CachePort, "Waiting for snoop response to be sent\n");
2596 Tick when = snoopRespQueue.deferredPacketReadyTime();
2597 schedSendEvent(when);
2598
2599 if (delete_pkt)
2600 delete pkt;
2601
2602 return;
2603 }
2604
2605
2606 waitingOnRetry = !masterPort.sendTimingReq(pkt);
2607
2608 if (waitingOnRetry) {
2609 DPRINTF(CachePort, "now waiting on a retry\n");
2610 if (delete_pkt) {
2611 // we are awaiting a retry, but we
2612 // delete the packet and will be creating a new packet
2613 // when we get the opportunity
2614 delete pkt;
2615 }
2616 // note that we have now masked any requestBus and
2617 // schedSendEvent (we will wait for a retry before
2618 // doing anything), and this is so even if we do not
2619 // care about this packet and might override it before
2620 // it gets retried
2621 } else {
2622 // As part of the call to sendTimingReq the packet is
2623 // forwarded to all neighbouring caches (and any
2624 // caches above them) as a snoop. The packet is also
2625 // sent to any potential cache below as the
2626 // interconnect is not allowed to buffer the
2627 // packet. Thus at this point we know if any of the
2628 // neighbouring, or the downstream cache is
2629 // responding, and if so, if it is with a dirty line
2630 // or not.
2631 bool pending_dirty_resp = !pkt->sharedAsserted() &&
2632 pkt->memInhibitAsserted();
2633
2634 cache.markInService(mshr, pending_dirty_resp);
2635 }
2636 }
2637
2638 // if we succeeded and are not waiting for a retry, schedule the
2639 // next send considering when the next MSHR is ready, note that
2640 // snoop responses have their own packet queue and thus schedule
2641 // their own events
2642 if (!waitingOnRetry) {
2643 schedSendEvent(cache.nextMSHRReadyTime());
2644 }
2645}
2646
2647Cache::
2648MemSidePort::MemSidePort(const std::string &_name, Cache *_cache,
2649 const std::string &_label)
2650 : BaseCache::CacheMasterPort(_name, _cache, _reqQueue, _snoopRespQueue),
2651 _reqQueue(*_cache, *this, _snoopRespQueue, _label),
2652 _snoopRespQueue(*_cache, *this, _label), cache(_cache)
2653{
2654}
| 2342 // If we are getting a non-shared response it is dirty
2343 bool pending_dirty_resp = !snoop_pkt.sharedAsserted();
2344 markInService(mshr, pending_dirty_resp);
2345 DPRINTF(Cache, "Upward snoop of prefetch for addr"
2346 " %#x (%s) hit\n",
2347 tgt_pkt->getAddr(), tgt_pkt->isSecure()? "s": "ns");
2348 return NULL;
2349 }
2350
2351 if (snoop_pkt.isBlockCached() || blk != NULL) {
2352 DPRINTF(Cache, "Block present, prefetch squashed by cache. "
2353 "Deallocating mshr target %#x.\n",
2354 mshr->blkAddr);
2355
2356 // Deallocate the mshr target
2357 if (!tgt_pkt->isWriteback()) {
2358 if (mshr->queue->forceDeallocateTarget(mshr)) {
2359 // Clear block if this deallocation resulted freed an
2360 // mshr when all had previously been utilized
2361 clearBlocked((BlockedCause)(mshr->queue->index));
2362 }
2363 return NULL;
2364 } else {
2365 // If this is a Writeback, and the snoops indicate that the blk
2366 // is cached above, set the BLOCK_CACHED flag in the Writeback
2367 // packet, so that it does not reset the bits corresponding to
2368 // this block in the snoop filter below.
2369 tgt_pkt->setBlockCached();
2370 }
2371 }
2372 }
2373
2374 if (mshr->isForwardNoResponse()) {
2375 // no response expected, just forward packet as it is
2376 assert(tags->findBlock(mshr->blkAddr, mshr->isSecure) == NULL);
2377 pkt = tgt_pkt;
2378 } else {
2379 pkt = getBusPacket(tgt_pkt, blk, mshr->needsExclusive());
2380
2381 mshr->isForward = (pkt == NULL);
2382
2383 if (mshr->isForward) {
2384 // not a cache block request, but a response is expected
2385 // make copy of current packet to forward, keep current
2386 // copy for response handling
2387 pkt = new Packet(tgt_pkt, false, true);
2388 if (pkt->isWrite()) {
2389 pkt->setData(tgt_pkt->getConstPtr<uint8_t>());
2390 }
2391 }
2392 }
2393
2394 assert(pkt != NULL);
2395 // play it safe and append (rather than set) the sender state, as
2396 // forwarded packets may already have existing state
2397 pkt->pushSenderState(mshr);
2398 return pkt;
2399}
2400
2401
2402Tick
2403Cache::nextMSHRReadyTime() const
2404{
2405 Tick nextReady = std::min(mshrQueue.nextMSHRReadyTime(),
2406 writeBuffer.nextMSHRReadyTime());
2407
2408 // Don't signal prefetch ready time if no MSHRs available
2409 // Will signal once enoguh MSHRs are deallocated
2410 if (prefetcher && mshrQueue.canPrefetch()) {
2411 nextReady = std::min(nextReady,
2412 prefetcher->nextPrefetchReadyTime());
2413 }
2414
2415 return nextReady;
2416}
2417
2418void
2419Cache::serialize(CheckpointOut &cp) const
2420{
2421 bool dirty(isDirty());
2422
2423 if (dirty) {
2424 warn("*** The cache still contains dirty data. ***\n");
2425 warn(" Make sure to drain the system using the correct flags.\n");
2426 warn(" This checkpoint will not restore correctly and dirty data in "
2427 "the cache will be lost!\n");
2428 }
2429
2430 // Since we don't checkpoint the data in the cache, any dirty data
2431 // will be lost when restoring from a checkpoint of a system that
2432 // wasn't drained properly. Flag the checkpoint as invalid if the
2433 // cache contains dirty data.
2434 bool bad_checkpoint(dirty);
2435 SERIALIZE_SCALAR(bad_checkpoint);
2436}
2437
2438void
2439Cache::unserialize(CheckpointIn &cp)
2440{
2441 bool bad_checkpoint;
2442 UNSERIALIZE_SCALAR(bad_checkpoint);
2443 if (bad_checkpoint) {
2444 fatal("Restoring from checkpoints with dirty caches is not supported "
2445 "in the classic memory system. Please remove any caches or "
2446 " drain them properly before taking checkpoints.\n");
2447 }
2448}
2449
2450///////////////
2451//
2452// CpuSidePort
2453//
2454///////////////
2455
2456AddrRangeList
2457Cache::CpuSidePort::getAddrRanges() const
2458{
2459 return cache->getAddrRanges();
2460}
2461
2462bool
2463Cache::CpuSidePort::recvTimingReq(PacketPtr pkt)
2464{
2465 assert(!cache->system->bypassCaches());
2466
2467 bool success = false;
2468
2469 // always let inhibited requests through, even if blocked,
2470 // ultimately we should check if this is an express snoop, but at
2471 // the moment that flag is only set in the cache itself
2472 if (pkt->memInhibitAsserted()) {
2473 // do not change the current retry state
2474 bool M5_VAR_USED bypass_success = cache->recvTimingReq(pkt);
2475 assert(bypass_success);
2476 return true;
2477 } else if (blocked || mustSendRetry) {
2478 // either already committed to send a retry, or blocked
2479 success = false;
2480 } else {
2481 // pass it on to the cache, and let the cache decide if we
2482 // have to retry or not
2483 success = cache->recvTimingReq(pkt);
2484 }
2485
2486 // remember if we have to retry
2487 mustSendRetry = !success;
2488 return success;
2489}
2490
2491Tick
2492Cache::CpuSidePort::recvAtomic(PacketPtr pkt)
2493{
2494 return cache->recvAtomic(pkt);
2495}
2496
2497void
2498Cache::CpuSidePort::recvFunctional(PacketPtr pkt)
2499{
2500 // functional request
2501 cache->functionalAccess(pkt, true);
2502}
2503
2504Cache::
2505CpuSidePort::CpuSidePort(const std::string &_name, Cache *_cache,
2506 const std::string &_label)
2507 : BaseCache::CacheSlavePort(_name, _cache, _label), cache(_cache)
2508{
2509}
2510
2511Cache*
2512CacheParams::create()
2513{
2514 assert(tags);
2515
2516 return new Cache(this);
2517}
2518///////////////
2519//
2520// MemSidePort
2521//
2522///////////////
2523
2524bool
2525Cache::MemSidePort::recvTimingResp(PacketPtr pkt)
2526{
2527 cache->recvTimingResp(pkt);
2528 return true;
2529}
2530
2531// Express snooping requests to memside port
2532void
2533Cache::MemSidePort::recvTimingSnoopReq(PacketPtr pkt)
2534{
2535 // handle snooping requests
2536 cache->recvTimingSnoopReq(pkt);
2537}
2538
2539Tick
2540Cache::MemSidePort::recvAtomicSnoop(PacketPtr pkt)
2541{
2542 return cache->recvAtomicSnoop(pkt);
2543}
2544
2545void
2546Cache::MemSidePort::recvFunctionalSnoop(PacketPtr pkt)
2547{
2548 // functional snoop (note that in contrast to atomic we don't have
2549 // a specific functionalSnoop method, as they have the same
2550 // behaviour regardless)
2551 cache->functionalAccess(pkt, false);
2552}
2553
2554void
2555Cache::CacheReqPacketQueue::sendDeferredPacket()
2556{
2557 // sanity check
2558 assert(!waitingOnRetry);
2559
2560 // there should never be any deferred request packets in the
2561 // queue, instead we resly on the cache to provide the packets
2562 // from the MSHR queue or write queue
2563 assert(deferredPacketReadyTime() == MaxTick);
2564
2565 // check for request packets (requests & writebacks)
2566 PacketPtr pkt = cache.getTimingPacket();
2567 if (pkt == NULL) {
2568 // can happen if e.g. we attempt a writeback and fail, but
2569 // before the retry, the writeback is eliminated because
2570 // we snoop another cache's ReadEx.
2571 } else {
2572 MSHR *mshr = dynamic_cast<MSHR*>(pkt->senderState);
2573 // in most cases getTimingPacket allocates a new packet, and
2574 // we must delete it unless it is successfully sent
2575 bool delete_pkt = !mshr->isForwardNoResponse();
2576
2577 // let our snoop responses go first if there are responses to
2578 // the same addresses we are about to writeback, note that
2579 // this creates a dependency between requests and snoop
2580 // responses, but that should not be a problem since there is
2581 // a chain already and the key is that the snoop responses can
2582 // sink unconditionally
2583 if (snoopRespQueue.hasAddr(pkt->getAddr())) {
2584 DPRINTF(CachePort, "Waiting for snoop response to be sent\n");
2585 Tick when = snoopRespQueue.deferredPacketReadyTime();
2586 schedSendEvent(when);
2587
2588 if (delete_pkt)
2589 delete pkt;
2590
2591 return;
2592 }
2593
2594
2595 waitingOnRetry = !masterPort.sendTimingReq(pkt);
2596
2597 if (waitingOnRetry) {
2598 DPRINTF(CachePort, "now waiting on a retry\n");
2599 if (delete_pkt) {
2600 // we are awaiting a retry, but we
2601 // delete the packet and will be creating a new packet
2602 // when we get the opportunity
2603 delete pkt;
2604 }
2605 // note that we have now masked any requestBus and
2606 // schedSendEvent (we will wait for a retry before
2607 // doing anything), and this is so even if we do not
2608 // care about this packet and might override it before
2609 // it gets retried
2610 } else {
2611 // As part of the call to sendTimingReq the packet is
2612 // forwarded to all neighbouring caches (and any
2613 // caches above them) as a snoop. The packet is also
2614 // sent to any potential cache below as the
2615 // interconnect is not allowed to buffer the
2616 // packet. Thus at this point we know if any of the
2617 // neighbouring, or the downstream cache is
2618 // responding, and if so, if it is with a dirty line
2619 // or not.
2620 bool pending_dirty_resp = !pkt->sharedAsserted() &&
2621 pkt->memInhibitAsserted();
2622
2623 cache.markInService(mshr, pending_dirty_resp);
2624 }
2625 }
2626
2627 // if we succeeded and are not waiting for a retry, schedule the
2628 // next send considering when the next MSHR is ready, note that
2629 // snoop responses have their own packet queue and thus schedule
2630 // their own events
2631 if (!waitingOnRetry) {
2632 schedSendEvent(cache.nextMSHRReadyTime());
2633 }
2634}
2635
2636Cache::
2637MemSidePort::MemSidePort(const std::string &_name, Cache *_cache,
2638 const std::string &_label)
2639 : BaseCache::CacheMasterPort(_name, _cache, _reqQueue, _snoopRespQueue),
2640 _reqQueue(*_cache, *this, _snoopRespQueue, _label),
2641 _snoopRespQueue(*_cache, *this, _label), cache(_cache)
2642{
2643}
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