perf cs-etm: Make cs_etm__run_decoder() queue independent

This patch makes decoding of auxtrace buffer centered around a struct
cs_etm_queue.  This eliminates surperflous variables and is a precursor
for work that simplifies the main decoder loop.
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/20190212171618.25355-11-mathieu.poirier@linaro.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/cs-etm-decoder/cs-etm-decoder.h

@@ -15,13 +15,6 @@
 
 struct cs_etm_decoder;
 
-struct cs_etm_buffer {
-	const unsigned char *buf;
-	size_t len;
-	u64 offset;
-	u64 ref_timestamp;
-};
-
 enum cs_etm_sample_type {
 	CS_ETM_EMPTY,
 	CS_ETM_RANGE,

tools/perf/util/cs-etm.c

@@ -76,6 +76,8 @@ struct cs_etm_queue {
 	size_t last_branch_pos;
 	struct cs_etm_packet *prev_packet;
 	struct cs_etm_packet *packet;
+	const unsigned char *buf;
+	size_t buf_len, buf_used;
 };
 
 static int cs_etm__update_queues(struct cs_etm_auxtrace *etm);
@@ -683,7 +685,7 @@ static int cs_etm__inject_event(union perf_event *event,
 
 
 static int
-cs_etm__get_trace(struct cs_etm_buffer *buff, struct cs_etm_queue *etmq)
+cs_etm__get_trace(struct cs_etm_queue *etmq)
 {
 	struct auxtrace_buffer *aux_buffer = etmq->buffer;
 	struct auxtrace_buffer *old_buffer = aux_buffer;
@@ -697,7 +699,7 @@ cs_etm__get_trace(struct cs_etm_buffer *buff, struct cs_etm_queue *etmq)
 	if (!aux_buffer) {
 		if (old_buffer)
 			auxtrace_buffer__drop_data(old_buffer);
-		buff->len = 0;
+		etmq->buf_len = 0;
 		return 0;
 	}
 
@@ -717,13 +719,11 @@ cs_etm__get_trace(struct cs_etm_buffer *buff, struct cs_etm_queue *etmq)
 	if (old_buffer)
 		auxtrace_buffer__drop_data(old_buffer);
 
-	buff->offset = aux_buffer->offset;
-	buff->len = aux_buffer->size;
-	buff->buf = aux_buffer->data;
+	etmq->buf_used = 0;
+	etmq->buf_len = aux_buffer->size;
+	etmq->buf = aux_buffer->data;
 
-	buff->ref_timestamp = aux_buffer->reference;
-
-	return buff->len;
+	return etmq->buf_len;
 }
 
 static void cs_etm__set_pid_tid_cpu(struct cs_etm_auxtrace *etm,
@@ -1493,24 +1493,23 @@ static int cs_etm__set_sample_flags(struct cs_etm_queue *etmq)
 
 static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
 {
-	struct cs_etm_buffer buffer;
-	size_t buffer_used, processed;
+	size_t processed;
 	int err = 0;
 
 	/* Go through each buffer in the queue and decode them one by one */
 	while (1) {
-		buffer_used = 0;
-		memset(&buffer, 0, sizeof(buffer));
-		err = cs_etm__get_trace(&buffer, 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;
+		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;
+		}
 
 		/* Run trace decoder until buffer consumed or end of trace */
 		do {
@@ -1518,14 +1517,15 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
 			err = cs_etm_decoder__process_data_block(
 				etmq->decoder,
 				etmq->offset,
-				&buffer.buf[buffer_used],
-				buffer.len - buffer_used,
+				&etmq->buf[etmq->buf_used],
+				etmq->buf_len,
 				&processed);
 			if (err)
 				return err;
 
 			etmq->offset += processed;
-			buffer_used += processed;
+			etmq->buf_used += processed;
+			etmq->buf_len -= processed;
 
 			/* Process each packet in this chunk */
 			while (1) {
@@ -1585,7 +1585,7 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq)
 					break;
 				}
 			}
-		} while (buffer.len > buffer_used);
+		} while (etmq->buf_len);
 
 		if (err == 0)
 			/* Flush any remaining branch stack entries */