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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 <adrian.hunter@intel.com> Reviewed-by: Andi Kleen <ak@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Link: https://lore.kernel.org/r/20210430070309.17624-11-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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1 changed files with 9 additions and 3 deletions
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@ -1499,9 +1499,15 @@ static void intel_pt_calc_tsc_timestamp(struct intel_pt_decoder *decoder)
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timestamp = decoder->timestamp;
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}
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if (timestamp < decoder->timestamp) {
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intel_pt_log_to("Wraparound timestamp", timestamp);
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timestamp += (1ULL << 56);
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decoder->tsc_timestamp = timestamp;
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if (!decoder->buf_timestamp ||
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(timestamp + (1ULL << 56) < decoder->buf_timestamp)) {
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intel_pt_log_to("Wraparound timestamp", timestamp);
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timestamp += (1ULL << 56);
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decoder->tsc_timestamp = timestamp;
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} else {
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intel_pt_log_to("Suppressing bad timestamp", timestamp);
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timestamp = decoder->timestamp;
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}
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}
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decoder->timestamp = timestamp;
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decoder->timestamp_insn_cnt = 0;
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