From: Adrian Hunter adrian.hunter@intel.com
commit 61b6e08dc8e3ea80b7485c9b3f875ddd45c8466b upstream.
The decoder uses its current timestamp in samples. Usually that is a timestamp that has already passed, but in some cases it is a timestamp for a branch that the decoder is walking towards, and consequently hasn't reached.
The intel_pt_sample_time() function decides which is which, but was not handling TNT packets exactly correctly.
In the case of TNT, the timestamp applies to the first branch, so the decoder must first walk to that branch.
That means intel_pt_sample_time() should return true for TNT, and this patch makes that change. However, if the first branch is a non-taken branch (i.e. a 'N'), then intel_pt_sample_time() needs to return false for subsequent taken branches in the same TNT packet.
To handle that, introduce a new state INTEL_PT_STATE_TNT_CONT to distinguish the cases.
Note that commit 3f04d98e972b5 ("perf intel-pt: Improve sample timestamp") was also a stable fix and appears, for example, in v4.4 stable tree as commit a4ebb58fd124 ("perf intel-pt: Improve sample timestamp").
Signed-off-by: Adrian Hunter adrian.hunter@intel.com Cc: Jiri Olsa jolsa@redhat.com Cc: stable@vger.kernel.org # v4.4+ Fixes: 3f04d98e972b5 ("perf intel-pt: Improve sample timestamp") Link: http://lkml.kernel.org/r/20190510124143.27054-3-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c @@ -58,6 +58,7 @@ enum intel_pt_pkt_state { INTEL_PT_STATE_NO_IP, INTEL_PT_STATE_ERR_RESYNC, INTEL_PT_STATE_IN_SYNC, + INTEL_PT_STATE_TNT_CONT, INTEL_PT_STATE_TNT, INTEL_PT_STATE_TIP, INTEL_PT_STATE_TIP_PGD, @@ -72,8 +73,9 @@ static inline bool intel_pt_sample_time( case INTEL_PT_STATE_NO_IP: case INTEL_PT_STATE_ERR_RESYNC: case INTEL_PT_STATE_IN_SYNC: - case INTEL_PT_STATE_TNT: + case INTEL_PT_STATE_TNT_CONT: return true; + case INTEL_PT_STATE_TNT: case INTEL_PT_STATE_TIP: case INTEL_PT_STATE_TIP_PGD: case INTEL_PT_STATE_FUP: @@ -1256,7 +1258,9 @@ static int intel_pt_walk_tnt(struct inte return -ENOENT; } decoder->tnt.count -= 1; - if (!decoder->tnt.count) + if (decoder->tnt.count) + decoder->pkt_state = INTEL_PT_STATE_TNT_CONT; + else decoder->pkt_state = INTEL_PT_STATE_IN_SYNC; decoder->tnt.payload <<= 1; decoder->state.from_ip = decoder->ip; @@ -1287,7 +1291,9 @@ static int intel_pt_walk_tnt(struct inte
if (intel_pt_insn.branch == INTEL_PT_BR_CONDITIONAL) { decoder->tnt.count -= 1; - if (!decoder->tnt.count) + if (decoder->tnt.count) + decoder->pkt_state = INTEL_PT_STATE_TNT_CONT; + else decoder->pkt_state = INTEL_PT_STATE_IN_SYNC; if (decoder->tnt.payload & BIT63) { decoder->tnt.payload <<= 1; @@ -2356,6 +2362,7 @@ const struct intel_pt_state *intel_pt_de err = intel_pt_walk_trace(decoder); break; case INTEL_PT_STATE_TNT: + case INTEL_PT_STATE_TNT_CONT: err = intel_pt_walk_tnt(decoder); if (err == -EAGAIN) err = intel_pt_walk_trace(decoder);