From: Adrian Hunter Date: Fri, 30 Apr 2021 07:03:07 +0000 (+0300) Subject: perf intel-pt: Better 7-byte timestamp wraparound logic X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=31c7e27dae0e15ed466d8acced7e3a536e547b07;p=linux.git perf intel-pt: Better 7-byte timestamp wraparound logic A timestamp should not go backwards. If it does it is assumed that the 7-byte TSC packet value has wrapped. Improve that logic so that it will not allow the timestamp to go past the buffer timestamp (which is recorded when the buffer is copied out) Signed-off-by: Adrian Hunter Reviewed-by: Andi Kleen Cc: Jiri Olsa Link: https://lore.kernel.org/r/20210430070309.17624-11-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c index 7c93ae2bd56c9..c4044bc2fb86e 100644 --- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c @@ -1499,9 +1499,15 @@ static void intel_pt_calc_tsc_timestamp(struct intel_pt_decoder *decoder) timestamp = decoder->timestamp; } if (timestamp < decoder->timestamp) { - intel_pt_log_to("Wraparound timestamp", timestamp); - timestamp += (1ULL << 56); - decoder->tsc_timestamp = timestamp; + if (!decoder->buf_timestamp || + (timestamp + (1ULL << 56) < decoder->buf_timestamp)) { + intel_pt_log_to("Wraparound timestamp", timestamp); + timestamp += (1ULL << 56); + decoder->tsc_timestamp = timestamp; + } else { + intel_pt_log_to("Suppressing bad timestamp", timestamp); + timestamp = decoder->timestamp; + } } decoder->timestamp = timestamp; decoder->timestamp_insn_cnt = 0;