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....@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
>
