releases/4.19.31/perf-intel-pt-fix-overlap-calculation-for-padding.patch

   1 From 5a99d99e3310a565b0cf63f785b347be9ee0da45 Mon Sep 17 00:00:00 2001
   2 From: Adrian Hunter <adrian.hunter@intel.com>
   3 Date: Wed, 6 Feb 2019 12:39:44 +0200
   4 Subject: perf intel-pt: Fix overlap calculation for padding
   5
   6 From: Adrian Hunter <adrian.hunter@intel.com>
   7
   8 commit 5a99d99e3310a565b0cf63f785b347be9ee0da45 upstream.
   9
  10 Auxtrace records might have up to 7 bytes of padding appended. Adjust
  11 the overlap accordingly.
  12
  13 Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
  14 Cc: Jiri Olsa <jolsa@redhat.com>
  15 Cc: stable@vger.kernel.org
  16 Link: http://lkml.kernel.org/r/20190206103947.15750-3-adrian.hunter@intel.com
  17 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  18 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  19
  20 ---
  21  tools/perf/util/intel-pt-decoder/intel-pt-decoder.c |   36 ++++++++++++++++++--
  22  1 file changed, 34 insertions(+), 2 deletions(-)
  23
  24 --- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
  25 +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
  26 @@ -26,6 +26,7 @@
  27
  28  #include "../cache.h"
  29  #include "../util.h"
  30 +#include "../auxtrace.h"
  31
  32  #include "intel-pt-insn-decoder.h"
  33  #include "intel-pt-pkt-decoder.h"
  34 @@ -2558,6 +2559,34 @@ static int intel_pt_tsc_cmp(uint64_t tsc
  35         }
  36  }
  37
  38 +#define MAX_PADDING (PERF_AUXTRACE_RECORD_ALIGNMENT - 1)
  39 +
  40 +/**
  41 + * adj_for_padding - adjust overlap to account for padding.
  42 + * @buf_b: second buffer
  43 + * @buf_a: first buffer
  44 + * @len_a: size of first buffer
  45 + *
  46 + * @buf_a might have up to 7 bytes of padding appended. Adjust the overlap
  47 + * accordingly.
  48 + *
  49 + * Return: A pointer into @buf_b from where non-overlapped data starts
  50 + */
  51 +static unsigned char *adj_for_padding(unsigned char *buf_b,
  52 +                                     unsigned char *buf_a, size_t len_a)
  53 +{
  54 +       unsigned char *p = buf_b - MAX_PADDING;
  55 +       unsigned char *q = buf_a + len_a - MAX_PADDING;
  56 +       int i;
  57 +
  58 +       for (i = MAX_PADDING; i; i--, p++, q++) {
  59 +               if (*p != *q)
  60 +                       break;
  61 +       }
  62 +
  63 +       return p;
  64 +}
  65 +
  66  /**
  67   * intel_pt_find_overlap_tsc - determine start of non-overlapped trace data
  68   *                             using TSC.
  69 @@ -2608,8 +2637,11 @@ static unsigned char *intel_pt_find_over
  70
  71                         /* Same TSC, so buffers are consecutive */
  72                         if (!cmp && rem_b >= rem_a) {
  73 +                               unsigned char *start;
  74 +
  75                                 *consecutive = true;
  76 -                               return buf_b + len_b - (rem_b - rem_a);
  77 +                               start = buf_b + len_b - (rem_b - rem_a);
  78 +                               return adj_for_padding(start, buf_a, len_a);
  79                         }
  80                         if (cmp < 0)
  81                                 return buf_b; /* tsc_a < tsc_b => no overlap */
  82 @@ -2672,7 +2704,7 @@ unsigned char *intel_pt_find_overlap(uns
  83                 found = memmem(buf_a, len_a, buf_b, len_a);
  84                 if (found) {
  85                         *consecutive = true;
  86 -                       return buf_b + len_a;
  87 +                       return adj_for_padding(buf_b + len_a, buf_a, len_a);
  88                 }
  89
  90                 /* Try again at next PSB in buffer 'a' */