src/cpu/inorder/resources/fetch_unit.cc

   1 /*
   2  * Copyright (c) 2011 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Korey Sewell
  29  *
  30  */
  31
  32 #include <vector>
  33 #include <list>
  34
  35 #include "arch/isa_traits.hh"
  36 #include "arch/locked_mem.hh"
  37 #include "arch/utility.hh"
  38 #include "arch/predecoder.hh"
  39 #include "config/the_isa.hh"
  40 #include "cpu/inorder/resources/cache_unit.hh"
  41 #include "cpu/inorder/resources/fetch_unit.hh"
  42 #include "cpu/inorder/pipeline_traits.hh"
  43 #include "cpu/inorder/cpu.hh"
  44 #include "cpu/inorder/resource_pool.hh"
  45 #include "mem/request.hh"
  46
  47 using namespace std;
  48 using namespace TheISA;
  49 using namespace ThePipeline;
  50
  51 FetchUnit::FetchUnit(string res_name, int res_id, int res_width,
  52                      int res_latency, InOrderCPU *_cpu,
  53                      ThePipeline::Params *params)
  54     : CacheUnit(res_name, res_id, res_width, res_latency, _cpu, params),
  55       instSize(sizeof(TheISA::MachInst)), fetchBuffSize(params->fetchBuffSize),
  56       predecoder(NULL)
  57 { }
  58
  59 void
  60 FetchUnit::createMachInst(std::list<FetchBlock*>::iterator fetch_it,
  61                           DynInstPtr inst)
  62 {
  63     ExtMachInst ext_inst;
  64     Addr block_addr = cacheBlockAlign(inst->getMemAddr());
  65     Addr fetch_addr = inst->getMemAddr();
  66     unsigned fetch_offset = (fetch_addr - block_addr) / instSize;
  67     ThreadID tid = inst->readTid();
  68     TheISA::PCState instPC = inst->pcState();
  69
  70
  71     DPRINTF(InOrderCachePort, "Creating instruction [sn:%i] w/fetch data @"
  72             "addr:%08p block:%08p\n", inst->seqNum, fetch_addr, block_addr);
  73
  74     assert((*fetch_it)->valid);
  75
  76     TheISA::MachInst *fetchInsts =
  77         reinterpret_cast<TheISA::MachInst *>((*fetch_it)->block);
  78
  79     MachInst mach_inst =
  80         TheISA::gtoh(fetchInsts[fetch_offset]);
  81
  82     predecoder.setTC(cpu->thread[tid]->getTC());
  83     predecoder.moreBytes(instPC, inst->instAddr(), mach_inst);
  84     ext_inst = predecoder.getExtMachInst(instPC);
  85
  86     inst->pcState(instPC);
  87     inst->setMachInst(ext_inst);
  88 }
  89
  90 int
  91 FetchUnit::getSlot(DynInstPtr inst)
  92 {
  93     if (tlbBlocked[inst->threadNumber]) {
  94         return -1;
  95     }
  96
  97     if (!inst->validMemAddr()) {
  98         panic("[tid:%i][sn:%i] Mem. Addr. must be set before requesting "
  99               "cache access\n", inst->readTid(), inst->seqNum);
 100     }
 101
 102     int new_slot = Resource::getSlot(inst);
 103
 104     if (new_slot == -1)
 105         return -1;
 106
 107     inst->memTime = curTick();
 108     return new_slot;
 109 }
 110
 111 void
 112 FetchUnit::removeAddrDependency(DynInstPtr inst)
 113 {
 114     inst->unsetMemAddr();
 115 }
 116
 117 ResReqPtr
 118 FetchUnit::getRequest(DynInstPtr inst, int stage_num, int res_idx,
 119                      int slot_num, unsigned cmd)
 120 {
 121     ScheduleEntry* sched_entry = *inst->curSkedEntry;
 122     CacheRequest* cache_req = dynamic_cast<CacheRequest*>(reqs[slot_num]);
 123
 124     if (!inst->validMemAddr()) {
 125         panic("Mem. Addr. must be set before requesting cache access\n");
 126     }
 127
 128     assert(sched_entry->cmd == InitiateFetch);
 129
 130     DPRINTF(InOrderCachePort,
 131             "[tid:%i]: Fetch request from [sn:%i] for addr %08p\n",
 132             inst->readTid(), inst->seqNum, inst->getMemAddr());
 133
 134     cache_req->setRequest(inst, stage_num, id, slot_num,
 135                           sched_entry->cmd, MemCmd::ReadReq,
 136                           inst->curSkedEntry->idx);
 137
 138     return cache_req;
 139 }
 140
 141 void
 142 FetchUnit::setupMemRequest(DynInstPtr inst, CacheReqPtr cache_req,
 143                            int acc_size, int flags)
 144 {
 145     ThreadID tid = inst->readTid();
 146     Addr aligned_addr = cacheBlockAlign(inst->getMemAddr());
 147
 148     inst->fetchMemReq =
 149             new Request(tid, aligned_addr, acc_size, flags,
 150                         inst->instAddr(), cpu->readCpuId(), tid);
 151
 152     cache_req->memReq = inst->fetchMemReq;
 153 }
 154
 155 std::list<FetchUnit::FetchBlock*>::iterator
 156 FetchUnit::findBlock(std::list<FetchBlock*> &fetch_blocks, int asid,
 157                      Addr block_addr)
 158 {
 159     std::list<FetchBlock*>::iterator fetch_it = fetch_blocks.begin();
 160     std::list<FetchBlock*>::iterator end_it = fetch_blocks.end();
 161
 162     while (fetch_it != end_it) {
 163         if ((*fetch_it)->asid == asid &&
 164             (*fetch_it)->addr == block_addr) {
 165             return fetch_it;
 166         }
 167
 168         fetch_it++;
 169     }
 170
 171     return fetch_it;
 172 }
 173
 174 std::list<FetchUnit::FetchBlock*>::iterator
 175 FetchUnit::findReplacementBlock()
 176 {
 177     std::list<FetchBlock*>::iterator fetch_it = fetchBuffer.begin();
 178     std::list<FetchBlock*>::iterator end_it = fetchBuffer.end();
 179
 180     while (fetch_it != end_it) {
 181         if ((*fetch_it)->cnt == 0) {
 182             return fetch_it;
 183         } else {
 184             DPRINTF(InOrderCachePort, "Block %08p has %i insts pending.\n",
 185                     (*fetch_it)->addr, (*fetch_it)->cnt);
 186         }
 187         fetch_it++;
 188     }
 189
 190     return fetch_it;
 191 }
 192
 193 void
 194 FetchUnit::markBlockUsed(std::list<FetchBlock*>::iterator block_it)
 195 {
 196     // Move block from whatever location it is in fetch buffer
 197     // to the back (represents most-recently-used location)
 198     if (block_it != fetchBuffer.end()) {
 199         FetchBlock *mru_blk = *block_it;
 200         fetchBuffer.erase(block_it);
 201         fetchBuffer.push_back(mru_blk);
 202     }
 203 }
 204
 205 void
 206 FetchUnit::execute(int slot_num)
 207 {
 208     CacheReqPtr cache_req = dynamic_cast<CacheReqPtr>(reqs[slot_num]);
 209     assert(cache_req);
 210
 211     if (cachePortBlocked && cache_req->cmd == InitiateFetch) {
 212         DPRINTF(InOrderCachePort, "Cache Port Blocked. Cannot Access\n");
 213         cache_req->done(false);
 214         return;
 215     }
 216
 217     DynInstPtr inst = cache_req->inst;
 218     ThreadID tid = inst->readTid();
 219     Addr block_addr = cacheBlockAlign(inst->getMemAddr());
 220     int asid = cpu->asid[tid];
 221
 222     inst->fault = NoFault;
 223
 224     switch (cache_req->cmd)
 225     {
 226       case InitiateFetch:
 227         {
 228             // Check to see if we've already got this request buffered
 229             // or pending to be buffered
 230             bool do_fetch = true;
 231             std::list<FetchBlock*>::iterator pending_it;
 232             pending_it = findBlock(pendingFetch, asid, block_addr);
 233             if (pending_it != pendingFetch.end()) {
 234                 (*pending_it)->cnt++;
 235                 do_fetch = false;
 236
 237                 DPRINTF(InOrderCachePort, "%08p is a pending fetch block "
 238                         "(pending:%i).\n", block_addr,
 239                         (*pending_it)->cnt);
 240             } else if (pendingFetch.size() < fetchBuffSize) {
 241                 std::list<FetchBlock*>::iterator buff_it;
 242                 buff_it = findBlock(fetchBuffer, asid, block_addr);
 243                 if (buff_it  != fetchBuffer.end()) {
 244                     (*buff_it)->cnt++;
 245                     do_fetch = false;
 246
 247                     DPRINTF(InOrderCachePort, "%08p is in fetch buffer"
 248                             "(pending:%i).\n", block_addr, (*buff_it)->cnt);
 249                 }
 250             }
 251
 252             if (!do_fetch) {
 253                 DPRINTF(InOrderCachePort, "Inst. [sn:%i] marked to be filled "
 254                         "through fetch buffer.\n", inst->seqNum);
 255                 cache_req->fetchBufferFill = true;
 256                 cache_req->setCompleted(true);
 257                 return;
 258             }
 259
 260             // Check to see if there is room in the fetchbuffer for this instruction.
 261             // If not, block this request.
 262             if (pendingFetch.size() >= fetchBuffSize) {
 263                 DPRINTF(InOrderCachePort, "No room available in fetch buffer.\n");
 264                 cache_req->done();
 265                 return;
 266             }
 267
 268             doTLBAccess(inst, cache_req, cacheBlkSize, 0, TheISA::TLB::Execute);
 269
 270             if (inst->fault == NoFault) {
 271                 DPRINTF(InOrderCachePort,
 272                         "[tid:%u]: Initiating fetch access to %s for "
 273                         "addr:%#x (block:%#x)\n", tid, name(),
 274                         cache_req->inst->getMemAddr(), block_addr);
 275
 276                 cache_req->reqData = new uint8_t[cacheBlkSize];
 277
 278                 inst->setCurResSlot(slot_num);
 279
 280                 doCacheAccess(inst);
 281
 282                 if (cache_req->isMemAccPending()) {
 283                     pendingFetch.push_back(new FetchBlock(asid, block_addr));
 284                 }
 285             }
 286
 287             break;
 288         }
 289
 290       case CompleteFetch:
 291         if (cache_req->fetchBufferFill) {
 292             // Block request if it's depending on a previous fetch, but it hasnt made it yet
 293             std::list<FetchBlock*>::iterator fetch_it = findBlock(fetchBuffer, asid, block_addr);
 294             if (fetch_it == fetchBuffer.end()) {
 295                 DPRINTF(InOrderCachePort, "%#x not available yet\n",
 296                         block_addr);
 297                 cache_req->setCompleted(false);
 298                 return;
 299             }
 300
 301             // Make New Instruction
 302             createMachInst(fetch_it, inst);
 303             if (inst->traceData) {
 304                 inst->traceData->setStaticInst(inst->staticInst);
 305                 inst->traceData->setPC(inst->pcState());
 306             }
 307
 308             // FetchBuffer Book-Keeping
 309             (*fetch_it)->cnt--;
 310             assert((*fetch_it)->cnt >= 0);
 311             markBlockUsed(fetch_it);
 312
 313             cache_req->done();
 314             return;
 315         }
 316
 317         if (cache_req->isMemAccComplete()) {
 318             if (fetchBuffer.size() >= fetchBuffSize) {
 319                 // If there is no replacement block, then we'll just have
 320                 // to wait till that gets cleared before satisfying the fetch
 321                 // for this instruction
 322                 std::list<FetchBlock*>::iterator repl_it  =
 323                     findReplacementBlock();
 324                 if (repl_it == fetchBuffer.end()) {
 325                     DPRINTF(InOrderCachePort, "Unable to find replacement block"
 326                             " and complete fetch.\n");
 327                     cache_req->setCompleted(false);
 328                     return;
 329                 }
 330
 331                 fetchBuffer.erase(repl_it);
 332             }
 333
 334             DPRINTF(InOrderCachePort,
 335                     "[tid:%i]: Completing Fetch Access for [sn:%i]\n",
 336                     tid, inst->seqNum);
 337
 338             // Make New Instruction
 339             std::list<FetchBlock*>::iterator fetch_it  =
 340                 findBlock(pendingFetch, asid, block_addr);
 341
 342             assert(fetch_it != pendingFetch.end());
 343             assert((*fetch_it)->valid);
 344
 345             createMachInst(fetch_it, inst);
 346             if (inst->traceData) {
 347                 inst->traceData->setStaticInst(inst->staticInst);
 348                 inst->traceData->setPC(inst->pcState());
 349             }
 350
 351
 352             // Update instructions waiting on new fetch block
 353             FetchBlock *new_block = (*fetch_it);
 354             new_block->cnt--;
 355             assert(new_block->cnt >= 0);
 356
 357             // Finally, update FetchBuffer w/Pending Block into the
 358             // MRU location
 359             pendingFetch.erase(fetch_it);
 360             fetchBuffer.push_back(new_block);
 361
 362             DPRINTF(InOrderCachePort, "[tid:%i]: Instruction [sn:%i] is: %s\n",
 363                     tid, inst->seqNum,
 364                     inst->staticInst->disassemble(inst->instAddr()));
 365
 366             inst->unsetMemAddr();
 367
 368             delete cache_req->dataPkt;
 369
 370             cache_req->done();
 371         } else {
 372             DPRINTF(InOrderCachePort,
 373                      "[tid:%i]: [sn:%i]: Unable to Complete Fetch Access\n",
 374                     tid, inst->seqNum);
 375             DPRINTF(InOrderStall,
 376                     "STALL: [tid:%i]: Fetch miss from %08p\n",
 377                     tid, cache_req->inst->instAddr());
 378             cache_req->setCompleted(false);
 379             // NOTE: For SwitchOnCacheMiss ThreadModel, we *don't* switch on
 380             //       fetch miss, but we could ...
 381             // cache_req->setMemStall(true);
 382         }
 383         break;
 384
 385       default:
 386         fatal("Unrecognized command to %s", resName);
 387     }
 388 }
 389
 390 void
 391 FetchUnit::processCacheCompletion(PacketPtr pkt)
 392 {
 393     // Cast to correct packet type
 394     CacheReqPacket* cache_pkt = dynamic_cast<CacheReqPacket*>(pkt);
 395     assert(cache_pkt);
 396
 397     if (cache_pkt->cacheReq->isSquashed()) {
 398         DPRINTF(InOrderCachePort,
 399                 "Ignoring completion of squashed access, [tid:%i] [sn:%i]\n",
 400                 cache_pkt->cacheReq->getInst()->readTid(),
 401                 cache_pkt->cacheReq->getInst()->seqNum);
 402         DPRINTF(RefCount,
 403                 "Ignoring completion of squashed access, [tid:%i] [sn:%i]\n",
 404                 cache_pkt->cacheReq->getTid(),
 405                 cache_pkt->cacheReq->seqNum);
 406
 407         cache_pkt->cacheReq->done();
 408         cache_pkt->cacheReq->freeSlot();
 409         delete cache_pkt;
 410
 411         cpu->wakeCPU();
 412         return;
 413     }
 414
 415     Addr block_addr = cacheBlockAlign(cache_pkt->cacheReq->
 416                                       getInst()->getMemAddr());
 417
 418     DPRINTF(InOrderCachePort,
 419             "[tid:%u]: [sn:%i]: Waking from fetch access to addr:%#x(phys:%#x), size:%i\n",
 420             cache_pkt->cacheReq->getInst()->readTid(),
 421             cache_pkt->cacheReq->getInst()->seqNum,
 422             block_addr, cache_pkt->getAddr(), cache_pkt->getSize());
 423
 424     // Cast to correct request type
 425     CacheRequest *cache_req = dynamic_cast<CacheReqPtr>(
 426         findRequest(cache_pkt->cacheReq->getInst(), cache_pkt->instIdx));
 427
 428     if (!cache_req) {
 429         panic("[tid:%u]: [sn:%i]: Can't find slot for fetch access to "
 430               "addr. %08p\n", cache_pkt->cacheReq->getInst()->readTid(),
 431               cache_pkt->cacheReq->getInst()->seqNum,
 432               block_addr);
 433     }
 434
 435     // Get resource request info
 436     unsigned stage_num = cache_req->getStageNum();
 437     DynInstPtr inst = cache_req->inst;
 438     ThreadID tid = cache_req->inst->readTid();
 439     short asid = cpu->asid[tid];
 440
 441     assert(!cache_req->isSquashed());
 442     assert(inst->curSkedEntry->cmd == CompleteFetch);
 443
 444     DPRINTF(InOrderCachePort,
 445             "[tid:%u]: [sn:%i]: Processing fetch access for block %#x\n",
 446             tid, inst->seqNum, block_addr);
 447
 448     std::list<FetchBlock*>::iterator pend_it = findBlock(pendingFetch, asid,
 449                                                          block_addr);
 450     assert(pend_it != pendingFetch.end());
 451
 452     // Copy Data to pendingFetch queue...
 453     (*pend_it)->block = new uint8_t[cacheBlkSize];
 454     memcpy((*pend_it)->block, cache_pkt->getPtr<uint8_t>(), cacheBlkSize);
 455     (*pend_it)->valid = true;
 456
 457     cache_req->setMemAccPending(false);
 458     cache_req->setMemAccCompleted();
 459
 460     if (cache_req->isMemStall() &&
 461         cpu->threadModel == InOrderCPU::SwitchOnCacheMiss) {
 462         DPRINTF(InOrderCachePort, "[tid:%u] Waking up from Cache Miss.\n",
 463                 tid);
 464
 465         cpu->activateContext(tid);
 466
 467         DPRINTF(ThreadModel, "Activating [tid:%i] after return from cache"
 468                 "miss.\n", tid);
 469     }
 470
 471     // Wake up the CPU (if it went to sleep and was waiting on this
 472     // completion event).
 473     cpu->wakeCPU();
 474
 475     DPRINTF(Activity, "[tid:%u] Activating %s due to cache completion\n",
 476             tid, cpu->pipelineStage[stage_num]->name());
 477
 478     cpu->switchToActive(stage_num);
 479 }
 480
 481 void
 482 FetchUnit::squashCacheRequest(CacheReqPtr req_ptr)
 483 {
 484     DynInstPtr inst = req_ptr->getInst();
 485     ThreadID tid = inst->readTid();
 486     Addr block_addr = cacheBlockAlign(inst->getMemAddr());
 487     int asid = cpu->asid[tid];
 488
 489     // Check Fetch Buffer (or pending fetch) for this block and
 490     // update pending counts
 491     std::list<FetchBlock*>::iterator buff_it = findBlock(fetchBuffer,
 492                                                          asid,
 493                                                          block_addr);
 494     if (buff_it != fetchBuffer.end()) {
 495         (*buff_it)->cnt--;
 496         DPRINTF(InOrderCachePort, "[sn:%i] Removing Pending Fetch "
 497                 "for Buffer block %08p (cnt=%i)\n", inst->seqNum,
 498                 block_addr, (*buff_it)->cnt);
 499     } else {
 500         std::list<FetchBlock*>::iterator block_it = findBlock(pendingFetch,
 501                                                               asid,
 502                                                               block_addr);
 503         if (block_it != pendingFetch.end()) {
 504             (*block_it)->cnt--;
 505             if ((*block_it)->cnt == 0) {
 506                 DPRINTF(InOrderCachePort, "[sn:%i] Removing Pending Fetch "
 507                         "for block %08p (cnt=%i)\n", inst->seqNum,
 508                         block_addr, (*block_it)->cnt);
 509                 pendingFetch.erase(block_it);
 510             }
 511         }
 512     }
 513
 514     CacheUnit::squashCacheRequest(req_ptr);
 515 }
 516