[S390] ptrace cleanup

Overhaul program event recording and the code dealing with the ptrace
user space interface.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index ee7ac8b..abbb3c3 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -505,7 +505,7 @@
 			 * Let tracing know that we've done the handler setup.
 			 */
 			tracehook_signal_handler(signr, &info, &ka, regs,
-					current->thread.per_info.single_step);
+					test_thread_flag(TIF_SINGLE_STEP));
 		}
 		return;
 	}