perf cs-etm: Set sample flags for trace discontinuity

In the middle of trace stream, it might be interrupted thus the trace
data is not continuous, the trace stream firstly is ended for previous
trace block and restarted for next block.

To display related information for showing trace is restarted, this
patch set sample flags for trace discontinuity:

- If one discontinuity packet is coming, append flag
  PERF_IP_FLAG_TRACE_END to the previous packet to indicate the trace
  has been ended;
- If one instruction packet is following discontinuity packet, this
  instruction packet is the first one packet to restarting trace.  So
  set flag PERF_IP_FLAG_TRACE_START to discontinuity packet, this flag
  will be used to generate sample when connect with the sequential
  instruction packet.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Robert Walker <robert.walker@arm.com>
Cc: Suzuki K Poulouse <suzuki.poulose@arm.com>
Cc: coresight ml <coresight@lists.linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190129122842.32041-4-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/cs-etm.c

@@ -1111,6 +1111,7 @@ static int cs_etm__end_block(struct cs_etm_queue *etmq)
 static int cs_etm__set_sample_flags(struct cs_etm_queue *etmq)
 {
 	struct cs_etm_packet *packet = etmq->packet;
+	struct cs_etm_packet *prev_packet = etmq->prev_packet;
 
 	switch (packet->sample_type) {
 	case CS_ETM_RANGE:
@@ -1170,8 +1171,26 @@ static int cs_etm__set_sample_flags(struct cs_etm_queue *etmq)
 		    packet->last_instr_subtype == OCSD_S_INSTR_V8_RET)
 			packet->flags = PERF_IP_FLAG_BRANCH |
 					PERF_IP_FLAG_RETURN;
+
+		/*
+		 * Decoder might insert a discontinuity in the middle of
+		 * instruction packets, fixup prev_packet with flag
+		 * PERF_IP_FLAG_TRACE_BEGIN to indicate restarting trace.
+		 */
+		if (prev_packet->sample_type == CS_ETM_DISCONTINUITY)
+			prev_packet->flags |= PERF_IP_FLAG_BRANCH |
+					      PERF_IP_FLAG_TRACE_BEGIN;
 		break;
 	case CS_ETM_DISCONTINUITY:
+		/*
+		 * The trace is discontinuous, if the previous packet is
+		 * instruction packet, set flag PERF_IP_FLAG_TRACE_END
+		 * for previous packet.
+		 */
+		if (prev_packet->sample_type == CS_ETM_RANGE)
+			prev_packet->flags |= PERF_IP_FLAG_BRANCH |
+					      PERF_IP_FLAG_TRACE_END;
+		break;
 	case CS_ETM_EXCEPTION:
 	case CS_ETM_EXCEPTION_RET:
 	case CS_ETM_EMPTY: