Messages in this thread | | | Date | Mon, 19 Nov 2018 16:22:02 -0700 | From | Mathieu Poirier <> | Subject | Re: [PATCH v2 2/2] perf cs-etm: Add support sample flags |
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On Sun, Nov 11, 2018 at 01:07:56PM +0800, Leo Yan wrote: > We have prepared the flags in the packet structure, so need to copy > the related value into sample structure thus perf tool can facilitate > sample flags. > > The PREV_PACKET contains the branch instruction flags and PACKET > actually contains the flags for next branch instruction. So this patch > is to set sample flags with 'etmq->prev_packet->flags'. > > This patch includes three fixing up for sample flags based on the > packets context: > > - If the packet is exception packet or exception return packet, update > the previous packet for exception specific flags; > - If there has TRACE_ON or TRACE_OFF packet in the middle of instruction > packets, this indicates the trace is discontinuous, so append the flag > PERF_IP_FLAG_TRACE_END to the previous packet to indicate the trace > has been ended; > - If one instruction packet is behind TRACE_OFF packet, this instruction > is restarting trace packet. So set flag PERF_IP_FLAG_TRACE_START to > TRACE_OFF packet if one, this flag isn't used by TRACE_OFF packet but > used to indicate trace restarting when generate sample. > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > --- > tools/perf/util/cs-etm.c | 43 +++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 41 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c > index 455f132..afca6f3 100644 > --- a/tools/perf/util/cs-etm.c > +++ b/tools/perf/util/cs-etm.c > @@ -676,7 +676,7 @@ static int cs_etm__synth_instruction_sample(struct cs_etm_queue *etmq, > sample.stream_id = etmq->etm->instructions_id; > sample.period = period; > sample.cpu = etmq->packet->cpu; > - sample.flags = 0; > + sample.flags = etmq->prev_packet->flags; > sample.insn_len = 1; > sample.cpumode = event->sample.header.misc; > > @@ -735,7 +735,7 @@ static int cs_etm__synth_branch_sample(struct cs_etm_queue *etmq) > sample.stream_id = etmq->etm->branches_id; > sample.period = 1; > sample.cpu = etmq->packet->cpu; > - sample.flags = 0; > + sample.flags = etmq->prev_packet->flags; > sample.cpumode = event->sample.header.misc; > > /* > @@ -878,6 +878,43 @@ static int cs_etm__synth_events(struct cs_etm_auxtrace *etm, > return 0; > } > > +static void cs_etm__fixup_flags(struct cs_etm_queue *etmq) > +{ > + /* > + * Decoding stream might insert one TRACE_OFF packet in the > + * middle of instruction packets, this means it doesn't > + * contain the pair packets with TRACE_OFF and TRACE_ON. > + * For this case, the instruction packet follows with > + * TRACE_OFF packet so we need to fixup prev_packet with flag > + * PERF_IP_FLAG_TRACE_BEGIN, this flag finally is used by the > + * instruction packet to generate samples. > + */ > + if (etmq->prev_packet->sample_type == CS_ETM_TRACE_OFF && > + etmq->packet->sample_type == CS_ETM_RANGE) > + etmq->prev_packet->flags = PERF_IP_FLAG_BRANCH | > + PERF_IP_FLAG_TRACE_BEGIN; > + > + if (etmq->prev_packet->sample_type == CS_ETM_RANGE) { > + /* > + * When the exception packet is inserted, update flags > + * so tell perf it is exception related branches. > + */ > + if (etmq->packet->sample_type == CS_ETM_EXCEPTION || > + etmq->packet->sample_type == CS_ETM_EXCEPTION_RET) > + etmq->prev_packet->flags = etmq->packet->flags; > + > + /* > + * The trace is discontinuous, weather this is caused by > + * TRACE_ON packet or TRACE_OFF packet is coming, if the > + * previous packet is instruction packet, simply set flag > + * PERF_IP_FLAG_TRACE_END for previous packet. > + */ > + if (etmq->packet->sample_type == CS_ETM_TRACE_ON || > + etmq->packet->sample_type == CS_ETM_TRACE_OFF) > + etmq->prev_packet->flags |= PERF_IP_FLAG_TRACE_END; > + } > +} > +
I think it would be better to keep all the flag related processing in cs-etm-decoder.c so that things in cs-etm.c are only concered with dealing with perf.
Look at function cs_etm__alloc_queue(), there you'll find "d_params.data = etmq".
In function cs_etm_decoder__new(), decoder->data = d_params->data;
This means that anywhere you have a decoder, decoder->data is an etmq. I've used this profusely in my work on CPU-wide trace scenarios. Because you're getting there ahead of me you'll need to fix the declaration of struct cs_etm_queue but that's easy.
Regards, Mathieu
> static int cs_etm__sample(struct cs_etm_queue *etmq) > { > struct cs_etm_auxtrace *etm = etmq->etm; > @@ -1100,6 +1137,8 @@ static int cs_etm__run_decoder(struct cs_etm_queue *etmq) > */ > break; > > + cs_etm__fixup_flags(etmq); > + > switch (etmq->packet->sample_type) { > case CS_ETM_RANGE: > /* > -- > 2.7.4 >
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