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;