cpu: Fix broken thread context handover

The thread context handover code used to break when multiple handovers
were performed during the same quiesce period. Previously, the thread
contexts would assign the TC pointer in the old quiesce event to the
new TC. This obviously broke in cases where multiple switches were
performed within the same quiesce period, in which case the TC pointer
in the quiesce event would point to an old CPU.

The new implementation deschedules pending quiesce events in the old
TC and schedules a new quiesce event in the new TC. The code has been
refactored to remove most of the code duplication.

1 files changed, 3 insertions, 27 deletions

diff --git a/src/cpu/o3/thread_context_impl.hh b/src/cpu/o3/thread_context_impl.hh
index 0a8dfeb3e..6de5c5731 100755
--- a/src/cpu/o3/thread_context_impl.hh
+++ b/src/cpu/o3/thread_context_impl.hh
@@ -66,34 +66,10 @@ template <class Impl>
 void
 O3ThreadContext<Impl>::takeOverFrom(ThreadContext *old_context)
 {
-    // some things should already be set up
-    assert(getSystemPtr() == old_context->getSystemPtr());
-    assert(getProcessPtr() == old_context->getProcessPtr());
+    ::takeOverFrom(*this, *old_context);
 
-    // copy over functional state
-    setStatus(old_context->status());
-    copyArchRegs(old_context);
-    setContextId(old_context->contextId());
-    setThreadId(old_context->threadId());
-
-    if (FullSystem) {
-        EndQuiesceEvent *other_quiesce = old_context->getQuiesceEvent();
-        if (other_quiesce) {
-            // Point the quiesce event's TC at this TC so that it wakes up
-            // the proper CPU.
-            other_quiesce->tc = this;
-        }
-        if (thread->quiesceEvent) {
-            thread->quiesceEvent->tc = this;
-        }
-
-        // Transfer kernel stats from one CPU to the other.
-        thread->kernelStats = old_context->getKernelStats();
-    } else {
-        thread->funcExeInst = old_context->readFuncExeInst();
-    }
-
-    old_context->setStatus(ThreadContext::Halted);
+    thread->kernelStats = old_context->getKernelStats();
+    thread->funcExeInst = old_context->readFuncExeInst();
 
     thread->noSquashFromTC = false;
     thread->trapPending = false;