mem: dump out port trace when address decode error

1. Add findPort(PacketPtr pkt) for getting the port trace from the Packet.
   Keep the findPort(AddrRange addr_range) for recvMemBackdoorReq(...)
2. With the debug flag `PortTrace` enabled, user can see the full path of
   the packet with the corresponding address when address error in xbar.

Change-Id: Iaf43ee2d7f8c46b9b84b2bc421a6bc3b02e01b3e

src/mem/coherent_xbar.cc

@@ -159,7 +159,7 @@ CoherentXBar::recvTimingReq(PacketPtr pkt, PortID cpu_side_port_id)
     assert(is_express_snoop == cache_responding);
 
     // determine the destination based on the destination address range
-    PortID mem_side_port_id = findPort(pkt->getAddrRange());
+    PortID mem_side_port_id = findPort(pkt);
 
     // test if the crossbar should be considered occupied for the current
     // port, and exclude express snoops from the check
@@ -563,7 +563,7 @@ CoherentXBar::recvTimingSnoopReq(PacketPtr pkt, PortID mem_side_port_id)
     // device responsible for the address range something is
     // wrong, hence there is nothing further to do as the packet
     // would be going back to where it came from
-    assert(findPort(pkt->getAddrRange()) == mem_side_port_id);
+    assert(findPort(pkt) == mem_side_port_id);
 }
 
 bool
@@ -799,7 +799,7 @@ CoherentXBar::recvAtomicBackdoor(PacketPtr pkt, PortID cpu_side_port_id,
 
     // even if we had a snoop response, we must continue and also
     // perform the actual request at the destination
-    PortID mem_side_port_id = findPort(pkt->getAddrRange());
+    PortID mem_side_port_id = findPort(pkt);
 
     if (sink_packet) {
         DPRINTF(CoherentXBar, "%s: Not forwarding %s\n", __func__,
@@ -1035,7 +1035,7 @@ CoherentXBar::recvFunctional(PacketPtr pkt, PortID cpu_side_port_id)
             }
         }
 
-        PortID dest_id = findPort(pkt->getAddrRange());
+        PortID dest_id = findPort(pkt);
 
         memSidePorts[dest_id]->sendFunctional(pkt);
     }

src/mem/noncoherent_xbar.cc

@@ -107,8 +107,8 @@ NoncoherentXBar::recvTimingReq(PacketPtr pkt, PortID cpu_side_port_id)
     // we should never see express snoops on a non-coherent crossbar
     assert(!pkt->isExpressSnoop());
 
-    // determine the destination based on the address
-    PortID mem_side_port_id = findPort(pkt->getAddrRange());
+    // determine the destination port
+    PortID mem_side_port_id = findPort(pkt);
 
     // test if the layer should be considered occupied for the current
     // port
@@ -255,7 +255,7 @@ NoncoherentXBar::recvAtomicBackdoor(PacketPtr pkt, PortID cpu_side_port_id,
     unsigned int pkt_cmd = pkt->cmdToIndex();
 
     // determine the destination port
-    PortID mem_side_port_id = findPort(pkt->getAddrRange());
+    PortID mem_side_port_id = findPort(pkt);
 
     // stats updates for the request
     pktCount[cpu_side_port_id][mem_side_port_id]++;
@@ -316,7 +316,7 @@ NoncoherentXBar::recvFunctional(PacketPtr pkt, PortID cpu_side_port_id)
     }
 
     // determine the destination port
-    PortID dest_id = findPort(pkt->getAddrRange());
+    PortID dest_id = findPort(pkt);
 
     // forward the request to the appropriate destination
     memSidePorts[dest_id]->sendFunctional(pkt);

src/mem/xbar.cc

@@ -45,6 +45,9 @@
 
 #include "mem/xbar.hh"
 
+#include <memory>
+#include <string>
+
 #include "base/logging.hh"
 #include "base/trace.hh"
 #include "debug/AddrRanges.hh"
@@ -328,7 +331,7 @@ BaseXBar::Layer<SrcType, DstType>::recvRetry()
 }
 
 PortID
-BaseXBar::findPort(AddrRange addr_range)
+BaseXBar::findPort(AddrRange addr_range, PacketPtr pkt)
 {
     // we should never see any address lookups before we've got the
     // ranges of all connected CPU-side-port modules
@@ -353,10 +356,17 @@ BaseXBar::findPort(AddrRange addr_range)
         return defaultPortID;
     }
 
-    // we should use the range for the default port and it did not
-    // match, or the default port is not set
-    fatal("Unable to find destination for %s on %s\n", addr_range.to_string(),
-          name());
+    // We should use the range for the default port and it did not match,
+    // or the default port is not set. Dump out the port trace if possible.
+    std::string port_trace = "";
+    if (pkt) {
+        std::shared_ptr<TracingExtension> ext =
+            pkt->getExtension<TracingExtension>();
+        port_trace = ext ? ext->getTraceInString() :
+            "Use --debug-flags=PortTrace to see the port trace of the packet.";
+    }
+    fatal("Unable to find destination for %s on %s\n%s\n",
+          addr_range.to_string(), name(), port_trace);
 }
 
 /** Function called by the port when the crossbar is receiving a range change.*/

src/mem/xbar.hh

@@ -344,9 +344,16 @@ class BaseXBar : public ClockedObject
      * given a packet with this address range.
      *
      * @param addr_range Address range to find port for.
-     * @return id of port that the packet should be sent out of.
+     * @param pkt Packet that containing the address range.
+     * @return id of port that the packet should be sent ou of.
      */
-    PortID findPort(AddrRange addr_range);
+    PortID findPort(AddrRange addr_range, PacketPtr pkt=nullptr);
+
+    PortID
+    findPort(PacketPtr pkt)
+    {
+        return findPort(pkt->getAddrRange(), pkt);
+    }
 
     /**
      * Return the address ranges the crossbar is responsible for.