misc: Generalize GDB single stepping.

The new single stepping implementation for x86 doesn't rely on any ISA
specific properties or functionality. This change pulls out the per ISA
implementation of those functions and promotes the X86 implementation to the
base class.

One drawback of that implementation is that the CPU might stop on an
instruction twice if it's affected by both breakpoints and single stepping.
While that might be a little surprising, it's harmless and would only happen
under somewhat unlikely circumstances.

2 files changed, 1 insertions, 39 deletions

diff --git a/src/arch/x86/remote_gdb.cc b/src/arch/x86/remote_gdb.cc
index b30bf5739..dd96037e0 100644
--- a/src/arch/x86/remote_gdb.cc
+++ b/src/arch/x86/remote_gdb.cc
@@ -61,7 +61,7 @@ using namespace std;
 using namespace X86ISA;
 
 RemoteGDB::RemoteGDB(System *_system, ThreadContext *c) :
-    BaseRemoteGDB(_system, c, GDB_REG_BYTES), singleStepEvent(this)
+    BaseRemoteGDB(_system, c, GDB_REG_BYTES)
 {}
 
 bool
@@ -89,14 +89,6 @@ RemoteGDB::acc(Addr va, size_t len)
 }
 
 void
-RemoteGDB::SingleStepEvent::process()
-{
-    if (!gdb->singleStepEvent.scheduled())
-        gdb->scheduleInstCommitEvent(&gdb->singleStepEvent, 1);
-    gdb->trap(SIGTRAP);
-}
-
-void
 RemoteGDB::getregs()
 {
     HandyM5Reg m5reg = context->readMiscRegNoEffect(MISCREG_M5_REG);
@@ -231,16 +223,3 @@ RemoteGDB::setregs()
         }
     }
 }
-
-void
-RemoteGDB::clearSingleStep()
-{
-    descheduleInstCommitEvent(&singleStepEvent);
-}
-
-void
-RemoteGDB::setSingleStep()
-{
-    if (!singleStepEvent.scheduled())
-        scheduleInstCommitEvent(&singleStepEvent, 1);
-}
diff --git a/src/arch/x86/remote_gdb.hh b/src/arch/x86/remote_gdb.hh
index b654fc2f8..f09d1e012 100644
--- a/src/arch/x86/remote_gdb.hh
+++ b/src/arch/x86/remote_gdb.hh
@@ -116,26 +116,9 @@ class RemoteGDB : public BaseRemoteGDB
     bool acc(Addr addr, size_t len);
 
   protected:
-    class SingleStepEvent : public Event
-    {
-      protected:
-        RemoteGDB *gdb;
-
-      public:
-        SingleStepEvent(RemoteGDB *g) : gdb(g)
-        {}
-
-        void process();
-    };
-
-    SingleStepEvent singleStepEvent;
-
     void getregs();
     void setregs();
 
-    void clearSingleStep();
-    void setSingleStep();
-
     bool checkBpLen(size_t len) { return len == 1; }
 };