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perf intel-pt: Ensure never to set 'last_ip' when packet 'count' is zero

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Intel PT uses IP compression based on the last IP. For decoding purposes,
'last IP' is not updated when a branch target has been suppressed, which is
indicated by IPBytes == 0. IPBytes is stored in the packet 'count', so
ensure never to set 'last_ip' when packet 'count' is zero.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1495786658-18063-7-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2017-05-26 11:17:07 +03:00 committed by Arnaldo Carvalho de Melo
parent ee14ac0ef6
commit f952eaceb0
1 changed files with 5 additions and 3 deletions
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8
tools/perf/util/intel-pt-decoder/intel-pt-decoder.c
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@ -1470,7 +1470,8 @@ static int intel_pt_walk_psbend(struct intel_pt_decoder *decoder)
case INTEL_PT_FUP:
decoder->pge = true;
intel_pt_set_last_ip(decoder);
if (decoder->packet.count)
intel_pt_set_last_ip(decoder);
break;
case INTEL_PT_MODE_TSX:
@ -1756,8 +1757,9 @@ static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
static inline bool intel_pt_have_ip(struct intel_pt_decoder *decoder)
{
return decoder->have_last_ip || decoder->packet.count == 0 ||
decoder->packet.count == 3 || decoder->packet.count == 6;
return decoder->packet.count &&
(decoder->have_last_ip || decoder->packet.count == 3 ||
decoder->packet.count == 6);
}
/* Walk PSB+ packets to get in sync. */