releases/4.4.177/perf-intel-pt-fix-cyc-timestamp-calculation-after-ovf.patch

   1 From 03997612904866abe7cdcc992784ef65cb3a4b81 Mon Sep 17 00:00:00 2001
   2 From: Adrian Hunter <adrian.hunter@intel.com>
   3 Date: Wed, 6 Feb 2019 12:39:45 +0200
   4 Subject: perf intel-pt: Fix CYC timestamp calculation after OVF
   5
   6 From: Adrian Hunter <adrian.hunter@intel.com>
   7
   8 commit 03997612904866abe7cdcc992784ef65cb3a4b81 upstream.
   9
  10 CYC packet timestamp calculation depends upon CBR which was being
  11 cleared upon overflow (OVF). That can cause errors due to failing to
  12 synchronize with sideband events. Even if a CBR change has been lost,
  13 the old CBR is still a better estimate than zero. So remove the clearing
  14 of CBR.
  15
  16 Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
  17 Cc: Jiri Olsa <jolsa@redhat.com>
  18 Cc: stable@vger.kernel.org
  19 Link: http://lkml.kernel.org/r/20190206103947.15750-4-adrian.hunter@intel.com
  20 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22
  23 ---
  24  tools/perf/util/intel-pt-decoder/intel-pt-decoder.c |    1 -
  25  1 file changed, 1 deletion(-)
  26
  27 --- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
  28 +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
  29 @@ -1281,7 +1281,6 @@ static int intel_pt_overflow(struct inte
  30  {
  31         intel_pt_log("ERROR: Buffer overflow\n");
  32         intel_pt_clear_tx_flags(decoder);
  33 -       decoder->cbr = 0;
  34         decoder->timestamp_insn_cnt = 0;
  35         decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
  36         decoder->overflow = true;