From: Leo Yan <leo....@linaro.org> The CoreSight tracer driver might insert barrier packets between different buffers, thus the decoder can spot the boundaries based on the barrier packet; it is possible for the decoder to hit a barrier packet and emit a NO_SYNC element, then the decoder will find a periodic synchronisation point inside that next trace block that starts the trace again but does not have the TRACE_ON element as indicator - usually because this trace block has wrapped the buffer so we have lost the original point when the trace was enabled.
In the first case it causes the insertion of a OCSD_GEN_TRC_ELEM_NO_SYNC in the middle of the tracing stream, but as we were not handling the NO_SYNC element properly this ends up making users miss the discontinuity indications. Though OCSD_GEN_TRC_ELEM_NO_SYNC is different from CS_ETM_TRACE_ON when output from the decoder, both indicate that the trace data is discontinuous; this patch treats OCSD_GEN_TRC_ELEM_NO_SYNC as a trace discontinuity and generates a CS_ETM_DISCONTINUITY packet for it, so cs-etm can handle the discontinuity for this case, finally it saves the last trace data for the previous trace block and restart samples for the new block. Signed-off-by: Leo Yan <leo....@linaro.org> Reviewed-by: Mathieu Poirier <mathieu.poir...@linaro.org> Cc: Alexander Shishkin <alexander.shish...@linux.intel.com> Cc: Jiri Olsa <jo...@redhat.com> Cc: Mike Leach <mike.le...@linaro.org> Cc: Namhyung Kim <namhy...@kernel.org> Cc: Robert Walker <robert.wal...@arm.com> Cc: coresight ml <coresi...@lists.linaro.org> Cc: linux-arm-ker...@lists.infradead.org Link: http://lkml.kernel.org/r/1544513908-16805-7-git-send-email-leo....@linaro.org Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com> --- tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 1 - 1 file changed, 1 deletion(-) diff --git a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c index 1039f364f4cc..bee026e76a4c 100644 --- a/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c +++ b/tools/perf/util/cs-etm-decoder/cs-etm-decoder.c @@ -410,7 +410,6 @@ static ocsd_datapath_resp_t cs_etm_decoder__gen_trace_elem_printer( case OCSD_GEN_TRC_ELEM_UNKNOWN: break; case OCSD_GEN_TRC_ELEM_NO_SYNC: - break; case OCSD_GEN_TRC_ELEM_TRACE_ON: resp = cs_etm_decoder__buffer_discontinuity(decoder, trace_chan_id); -- 2.19.2
