releases/4.8.5/perf-intel-pt-fix-mtc-timestamp-calculation-for-large-mtc-periods.patch

   1 From 3bccbe20f6d188ce7b00326e776b745cfd35b10a Mon Sep 17 00:00:00 2001
   2 From: Adrian Hunter <adrian.hunter@intel.com>
   3 Date: Wed, 28 Sep 2016 14:41:36 +0300
   4 Subject: perf intel-pt: Fix MTC timestamp calculation for large MTC periods
   5
   6 From: Adrian Hunter <adrian.hunter@intel.com>
   7
   8 commit 3bccbe20f6d188ce7b00326e776b745cfd35b10a upstream.
   9
  10 The MTC packet provides a 8-bit slice of CTC which is related to TSC by
  11 the TMA packet, however the TMA packet only provides the lower 16 bits
  12 of CTC.  If mtc_shift > 8 then some of the MTC bits are not in the CTC
  13 provided by the TMA packet. Fix-up the last_mtc calculated from the TMA
  14 packet by copying the missing bits from the current MTC assuming the
  15 least difference between the two, and that the current MTC comes after
  16 last_mtc.
  17
  18 Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
  19 Cc: Jiri Olsa <jolsa@redhat.com>
  20 Link: http://lkml.kernel.org/r/1475062896-22274-2-git-send-email-adrian.hunter@intel.com
  21 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  23
  24 ---
  25  tools/perf/util/intel-pt-decoder/intel-pt-decoder.c |   36 ++++++++++++++++++++
  26  1 file changed, 36 insertions(+)
  27
  28 --- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
  29 +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
  30 @@ -89,6 +89,7 @@ struct intel_pt_decoder {
  31         bool pge;
  32         bool have_tma;
  33         bool have_cyc;
  34 +       bool fixup_last_mtc;
  35         uint64_t pos;
  36         uint64_t last_ip;
  37         uint64_t ip;
  38 @@ -584,10 +585,31 @@ struct intel_pt_calc_cyc_to_tsc_info {
  39         uint64_t        tsc_timestamp;
  40         uint64_t        timestamp;
  41         bool            have_tma;
  42 +       bool            fixup_last_mtc;
  43         bool            from_mtc;
  44         double          cbr_cyc_to_tsc;
  45  };
  46
  47 +/*
  48 + * MTC provides a 8-bit slice of CTC but the TMA packet only provides the lower
  49 + * 16 bits of CTC. If mtc_shift > 8 then some of the MTC bits are not in the CTC
  50 + * provided by the TMA packet. Fix-up the last_mtc calculated from the TMA
  51 + * packet by copying the missing bits from the current MTC assuming the least
  52 + * difference between the two, and that the current MTC comes after last_mtc.
  53 + */
  54 +static void intel_pt_fixup_last_mtc(uint32_t mtc, int mtc_shift,
  55 +                                   uint32_t *last_mtc)
  56 +{
  57 +       uint32_t first_missing_bit = 1U << (16 - mtc_shift);
  58 +       uint32_t mask = ~(first_missing_bit - 1);
  59 +
  60 +       *last_mtc |= mtc & mask;
  61 +       if (*last_mtc >= mtc) {
  62 +               *last_mtc -= first_missing_bit;
  63 +               *last_mtc &= 0xff;
  64 +       }
  65 +}
  66 +
  67  static int intel_pt_calc_cyc_cb(struct intel_pt_pkt_info *pkt_info)
  68  {
  69         struct intel_pt_decoder *decoder = pkt_info->decoder;
  70 @@ -617,6 +639,11 @@ static int intel_pt_calc_cyc_cb(struct i
  71                         return 0;
  72
  73                 mtc = pkt_info->packet.payload;
  74 +               if (decoder->mtc_shift > 8 && data->fixup_last_mtc) {
  75 +                       data->fixup_last_mtc = false;
  76 +                       intel_pt_fixup_last_mtc(mtc, decoder->mtc_shift,
  77 +                                               &data->last_mtc);
  78 +               }
  79                 if (mtc > data->last_mtc)
  80                         mtc_delta = mtc - data->last_mtc;
  81                 else
  82 @@ -685,6 +712,7 @@ static int intel_pt_calc_cyc_cb(struct i
  83
  84                 data->ctc_delta = 0;
  85                 data->have_tma = true;
  86 +               data->fixup_last_mtc = true;
  87
  88                 return 0;
  89
  90 @@ -751,6 +779,7 @@ static void intel_pt_calc_cyc_to_tsc(str
  91                 .tsc_timestamp  = decoder->tsc_timestamp,
  92                 .timestamp      = decoder->timestamp,
  93                 .have_tma       = decoder->have_tma,
  94 +               .fixup_last_mtc = decoder->fixup_last_mtc,
  95                 .from_mtc       = from_mtc,
  96                 .cbr_cyc_to_tsc = 0,
  97         };
  98 @@ -1241,6 +1270,7 @@ static void intel_pt_calc_tma(struct int
  99         }
 100         decoder->ctc_delta = 0;
 101         decoder->have_tma = true;
 102 +       decoder->fixup_last_mtc = true;
 103         intel_pt_log("CTC timestamp " x64_fmt " last MTC %#x  CTC rem %#x\n",
 104                      decoder->ctc_timestamp, decoder->last_mtc, ctc_rem);
 105  }
 106 @@ -1255,6 +1285,12 @@ static void intel_pt_calc_mtc_timestamp(
 107
 108         mtc = decoder->packet.payload;
 109
 110 +       if (decoder->mtc_shift > 8 && decoder->fixup_last_mtc) {
 111 +               decoder->fixup_last_mtc = false;
 112 +               intel_pt_fixup_last_mtc(mtc, decoder->mtc_shift,
 113 +                                       &decoder->last_mtc);
 114 +       }
 115 +
 116         if (mtc > decoder->last_mtc)
 117                 mtc_delta = mtc - decoder->last_mtc;
 118         else