提交 f952eace 编写于 作者: A Adrian Hunter 提交者: Arnaldo Carvalho de Melo

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

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: NAdrian 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.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
上级 ee14ac0e
......@@ -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. */
......
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