1 files changed, 44 insertions, 0 deletions
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index a714b31656ea..8b3f882d6e2f 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1372,6 +1372,20 @@ static int cs_etm__set_sample_flags(struct cs_etm_queue *etmq)
 		if (prev_packet->sample_type == CS_ETM_DISCONTINUITY)
 			prev_packet->flags |= PERF_IP_FLAG_BRANCH |
 					      PERF_IP_FLAG_TRACE_BEGIN;
+
+		/*
+		 * If the previous packet is an exception return packet
+		 * and the return address just follows SVC instuction,
+		 * it needs to calibrate the previous packet sample flags
+		 * as PERF_IP_FLAG_SYSCALLRET.
+		 */
+		if (prev_packet->flags == (PERF_IP_FLAG_BRANCH |
+					   PERF_IP_FLAG_RETURN |
+					   PERF_IP_FLAG_INTERRUPT) &&
+		    cs_etm__is_svc_instr(etmq, packet, packet->start_addr))
+			prev_packet->flags = PERF_IP_FLAG_BRANCH |
+					     PERF_IP_FLAG_RETURN |
+					     PERF_IP_FLAG_SYSCALLRET;
 		break;
 	case CS_ETM_DISCONTINUITY:
 		/*
@@ -1422,6 +1436,36 @@ static int cs_etm__set_sample_flags(struct cs_etm_queue *etmq)
 			prev_packet->flags = packet->flags;
 		break;
 	case CS_ETM_EXCEPTION_RET:
+		/*
+		 * When the exception return packet is inserted, since
+		 * exception return packet is not used standalone for
+		 * generating samples and it's affiliation to the previous
+		 * instruction range packet; so set previous range packet
+		 * flags to tell perf it is an exception return branch.
+		 *
+		 * The exception return can be for either system call or
+		 * other exception types; unfortunately the packet doesn't
+		 * contain exception type related info so we cannot decide
+		 * the exception type purely based on exception return packet.
+		 * If we record the exception number from exception packet and
+		 * reuse it for excpetion return packet, this is not reliable
+		 * due the trace can be discontinuity or the interrupt can
+		 * be nested, thus the recorded exception number cannot be
+		 * used for exception return packet for these two cases.
+		 *
+		 * For exception return packet, we only need to distinguish the
+		 * packet is for system call or for other types.  Thus the
+		 * decision can be deferred when receive the next packet which
+		 * contains the return address, based on the return address we
+		 * can read out the previous instruction and check if it's a
+		 * system call instruction and then calibrate the sample flag
+		 * as needed.
+		 */
+		if (prev_packet->sample_type == CS_ETM_RANGE)
+			prev_packet->flags = PERF_IP_FLAG_BRANCH |
+					     PERF_IP_FLAG_RETURN |
+					     PERF_IP_FLAG_INTERRUPT;
+		break;
 	case CS_ETM_EMPTY:
 	default:
 		break;