mem: Minor refactor of how the abstract mem backdoor is exposed.

Previously the SimpleMem depended on the fact that it inherited from the
AbstractMem in order to access and export it's back door. Now, the
AbstractMem has a method which will set a back door pointer if
appropriate, which the SimpleMem can use, or anything else which uses an
AbstractMem as its backing store.

Also, make the AbstractMem invalidate any existing back doors and refuse
to give out any new ones while some bit of memory is locked. That's
because if the storage is accessed directly, the AbstractMem will have
no change to manage its bookkeeping, and locking won't work properly.

Change-Id: If8c2a63e0827bb88b583f27ab4151d6b761e116e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36977
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

diff --git a/src/mem/abstract_mem.cc b/src/mem/abstract_mem.cc
index 3600f34fb4b76ae03b1687d2621b7df1c02c814f..7e098327a66241ff054841281b0c1f216229955e 100644 (file)
--- a/src/mem/abstract_mem.cc
+++ b/src/mem/abstract_mem.cc
@@ -269,6 +269,7 @@ AbstractMemory::trackLoadLocked(PacketPtr pkt)
     DPRINTF(LLSC, "Adding lock record: context %d addr %#x\n",
             req->contextId(), paddr);
     lockedAddrList.push_front(LockedAddr(req));
+    backdoor.invalidate();
 }
 
 

diff --git a/src/mem/abstract_mem.hh b/src/mem/abstract_mem.hh
index cd18e0f96663efade89c424889b6e5c88381fc54..1a3c01930eb3d891528d7aa2fd245f4e2c8a8dce 100644 (file)
--- a/src/mem/abstract_mem.hh
+++ b/src/mem/abstract_mem.hh
@@ -227,16 +227,31 @@ class AbstractMemory : public ClockedObject
      */
     void setBackingStore(uint8_t* pmem_addr);
 
+    void
+    getBackdoor(MemBackdoorPtr &bd_ptr)
+    {
+        if (lockedAddrList.empty() && backdoor.ptr())
+            bd_ptr = &backdoor;
+    }
+
     /**
      * Get the list of locked addresses to allow checkpointing.
      */
-    const std::list<LockedAddr>& getLockedAddrList() const
-    { return lockedAddrList; }
+    const std::list<LockedAddr> &
+    getLockedAddrList() const
+    {
+        return lockedAddrList;
+    }
 
     /**
      * Add a locked address to allow for checkpointing.
      */
-    void addLockedAddr(LockedAddr addr) { lockedAddrList.push_back(addr); }
+    void
+    addLockedAddr(LockedAddr addr)
+    {
+        backdoor.invalidate();
+        lockedAddrList.push_back(addr);
+    }
 
     /** read the system pointer
      * Implemented for completeness with the setter

diff --git a/src/mem/simple_mem.cc b/src/mem/simple_mem.cc
index 3ed3d04f3afed87fda62c5393a8d5ebe06748d2e..327a32622cce0e9c657246ddf2325039a858c1c3 100644 (file)
--- a/src/mem/simple_mem.cc
+++ b/src/mem/simple_mem.cc
@@ -80,9 +80,7 @@ Tick
 SimpleMemory::recvAtomicBackdoor(PacketPtr pkt, MemBackdoorPtr &_backdoor)
 {
     Tick latency = recvAtomic(pkt);
-
-    if (backdoor.ptr())
-        _backdoor = &backdoor;
+    getBackdoor(_backdoor);
     return latency;
 }