perf cs-etm: Modularize auxtrace_buffer fetch function

Making the auxtrace_buffer fetch function modular so that it can be
called from different decoding context (timeless vs. non-timeless),
avoiding to repeat code.

No change in functionality is introduced by this patch.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki K Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190212171618.25355-14-mathieu.poirier@linaro.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/cs-etm.c

@@ -1152,6 +1152,32 @@ static int cs_etm__end_block(struct cs_etm_queue *etmq)
 
 	return 0;
 }
+/*
+ * cs_etm__get_data_block: Fetch a block from the auxtrace_buffer queue
+ *			   if need be.
+ * Returns:	< 0	if error
+ *		= 0	if no more auxtrace_buffer to read
+ *		> 0	if the current buffer isn't empty yet
+ */
+static int cs_etm__get_data_block(struct cs_etm_queue *etmq)
+{
+	int ret;
+
+	if (!etmq->buf_len) {
+		ret = cs_etm__get_trace(etmq);
+		if (ret <= 0)
+			return ret;
+		/*
+		 * We cannot assume consecutive blocks in the data file
+		 * are contiguous, reset the decoder to force re-sync.
+		 */
+		ret = cs_etm_decoder__reset(etmq->decoder);
+		if (ret)
+			return ret;
+	}
+
+	return etmq->buf_len;
+}
 
 static bool cs_etm__is_svc_instr(struct cs_etm_queue *etmq,
 				 struct cs_etm_packet *packet,
@@ -1591,18 +1617,9 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
 
 	/* Go through each buffer in the queue and decode them one by one */
 	while (1) {
-		if (!etmq->buf_len) {
-			err = cs_etm__get_trace(etmq);
-			if (err <= 0)
-				return err;
-			/*
-			 * We cannot assume consecutive blocks in the data file
-			 * are contiguous, reset the decoder to force re-sync.
-			 */
-			err = cs_etm_decoder__reset(etmq->decoder);
-			if (err != 0)
-				return err;
-		}
+		err = cs_etm__get_data_block(etmq);
+		if (err <= 0)
+			return err;
 
 		/* Run trace decoder until buffer consumed or end of trace */
 		do {