mem-cache: fix invalid iterator access

[gem5.git] / src / mem / cache / mshr.cc

diff --git a/src/mem/cache/mshr.cc b/src/mem/cache/mshr.cc
index d6208dde97621166195726b55fd32ab5f9b3c19c..5b9302925831ae67751ff64fbbe28d497b9d5f14 100644 (file)
--- a/src/mem/cache/mshr.cc
+++ b/src/mem/cache/mshr.cc
@@ -40,6 +40,7 @@
  *
  * Authors: Erik Hallnor
  *          Dave Greene
+ *          Nikos Nikoleris
  */
 
 /**
@@ -63,7 +64,7 @@
 MSHR::MSHR() : downstreamPending(false),
                pendingModified(false),
                postInvalidate(false), postDowngrade(false),
-               isForward(false)
+               wasWholeLineWrite(false), isForward(false)
 {
 }
 
@@ -95,6 +96,8 @@ MSHR::TargetList::updateFlags(PacketPtr pkt, Target::Source source,
 
         if (source != Target::FromPrefetcher) {
             hasFromCache = hasFromCache || pkt->fromCache();
+
+            updateWriteFlags(pkt);
         }
     }
 }
@@ -207,10 +210,10 @@ MSHR::TargetList::clearDownstreamPending()
 
 
 bool
-MSHR::TargetList::checkFunctional(PacketPtr pkt)
+MSHR::TargetList::trySatisfyFunctional(PacketPtr pkt)
 {
     for (auto& t : *this) {
-        if (pkt->checkFunctional(t.pkt)) {
+        if (pkt->trySatisfyFunctional(t.pkt)) {
             return true;
         }
     }
@@ -257,16 +260,19 @@ MSHR::allocate(Addr blk_addr, unsigned blk_size, PacketPtr target,
     order = _order;
     assert(target);
     isForward = false;
+    wasWholeLineWrite = false;
     _isUncacheable = target->req->isUncacheable();
     inService = false;
     downstreamPending = false;
-    assert(targets.isReset());
+
+    targets.init(blkAddr, blkSize);
+    deferredTargets.init(blkAddr, blkSize);
+
     // Don't know of a case where we would allocate a new MSHR for a
     // snoop (mem-side request), so set source according to request here
     Target::Source source = (target->cmd == MemCmd::HardPFReq) ?
         Target::FromPrefetcher : Target::FromCPU;
     targets.add(target, when_ready, _order, source, true, alloc_on_fill);
-    assert(deferredTargets.isReset());
 }
 
 
@@ -294,6 +300,10 @@ MSHR::markInService(bool pending_modified_resp)
         // level where it's going to get a response
         targets.clearDownstreamPending();
     }
+    // if the line is not considered a whole-line write when sent
+    // downstream, make sure it is also not considered a whole-line
+    // write when receiving the response, and vice versa
+    wasWholeLineWrite = isWholeLineWrite();
 }
 
 
@@ -480,6 +490,7 @@ MSHR::TargetList
 MSHR::extractServiceableTargets(PacketPtr pkt)
 {
     TargetList ready_targets;
+    ready_targets.init(blkAddr, blkSize);
     // If the downstream MSHR got an invalidation request then we only
     // service the first of the FromCPU targets and any other
     // non-FromCPU target. This way the remaining FromCPU targets
@@ -548,6 +559,49 @@ MSHR::promoteDeferredTargets()
     return true;
 }
 
+void
+MSHR::promoteIf(const std::function<bool (Target &)>& pred)
+{
+    // if any of the deferred targets were upper-level cache
+    // requests marked downstreamPending, need to clear that
+    assert(!downstreamPending);  // not pending here anymore
+
+    // find the first target does not satisfy the condition
+    auto last_it = std::find_if_not(deferredTargets.begin(),
+                                    deferredTargets.end(),
+                                    pred);
+
+    // for the prefix of the deferredTargets [begin(), last_it) clear
+    // the downstreamPending flag and move them to the target list
+    deferredTargets.clearDownstreamPending(deferredTargets.begin(),
+                                           last_it);
+    targets.splice(targets.end(), deferredTargets,
+                   deferredTargets.begin(), last_it);
+    // We need to update the flags for the target lists after the
+    // modifications
+    deferredTargets.populateFlags();
+}
+
+void
+MSHR::promoteReadable()
+{
+    if (!deferredTargets.empty() && !hasPostInvalidate()) {
+        // We got a non invalidating response, and we have the block
+        // but we have deferred targets which are waiting and they do
+        // not need writable. This can happen if the original request
+        // was for a cache clean operation and we had a copy of the
+        // block. Since we serviced the cache clean operation and we
+        // have the block, there's no need to defer the targets, so
+        // move them up to the regular target list.
+
+        auto pred = [](Target &t) {
+            assert(t.source == Target::FromCPU);
+            return !t.pkt->req->isCacheInvalidate() &&
+                   !t.pkt->needsWritable();
+        };
+        promoteIf(pred);
+    }
+}
 
 void
 MSHR::promoteWritable()
@@ -563,29 +617,29 @@ MSHR::promoteWritable()
         // target list.
         assert(!targets.needsWritable);
         targets.needsWritable = true;
-        // if any of the deferred targets were upper-level cache
-        // requests marked downstreamPending, need to clear that
-        assert(!downstreamPending);  // not pending here anymore
-        deferredTargets.clearDownstreamPending();
-        // this clears out deferredTargets too
-        targets.splice(targets.end(), deferredTargets);
-        deferredTargets.resetFlags();
+
+        auto pred = [](Target &t) {
+            assert(t.source == Target::FromCPU);
+            return !t.pkt->req->isCacheInvalidate();
+        };
+
+        promoteIf(pred);
     }
 }
 
 
 bool
-MSHR::checkFunctional(PacketPtr pkt)
+MSHR::trySatisfyFunctional(PacketPtr pkt)
 {
     // For printing, we treat the MSHR as a whole as single entity.
     // For other requests, we iterate over the individual targets
     // since that's where the actual data lies.
     if (pkt->isPrint()) {
-        pkt->checkFunctional(this, blkAddr, isSecure, blkSize, nullptr);
+        pkt->trySatisfyFunctional(this, blkAddr, isSecure, blkSize, nullptr);
         return false;
     } else {
-        return (targets.checkFunctional(pkt) ||
-                deferredTargets.checkFunctional(pkt));
+        return (targets.trySatisfyFunctional(pkt) ||
+                deferredTargets.trySatisfyFunctional(pkt));
     }
 }