Re: [PATCH v3 3/4] perf cs-etm: Synthesize missing HW_ID mappings for raw trace

[sashiko-bot@kernel.org]

> From: Leo Yan <leo.yan@arm.com>
> 
> The CoreSight driver emits PERF_RECORD_AUX_OUTPUT_HW_ID via
> perf_report_aux_output_id(). If the perf ring buffer is full,
> perf_report_aux_output_id() can fail to emit the record and return
> silently.
> 
> When at least one HW_ID record is present in the file, perf skips the
> legacy metadata-only trace ID mapping path. Therefore any raw AUX queue
> whose HW_ID record was dropped can be left with an empty traceid_list,
> and cs_etm__create_queue_decoders() will not create a decoder for that
> queue.
> 
> Fix it by ignoring all HW_IDs for unformatted queues and always create
> one decoder per queue unconditionally. Trace ID is unused so we can hard
> code it to 1 (0 is a special value used in
> 'pending_timestamp_chan_id' to indicate not pending). We also need put
> the same trace ID in the CPU metadata because the relationship between
> CPU metadata and traceid_list is bidirectional. Moving
> cs_etm__metadata_set_trace_id() into the mapping function solves this
> and simplifies existing code. cs_etm__insert_trace_id_node() now does
> two things, so rename it to a more generic cs_etm__map_trace_id().
> 
> Signed-off-by: Leo Yan <leo.yan@arm.com>
> Signed-off-by: James Clark <james.clark@linaro.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261002-james-cs-hw_id-output-failure-v3-0-1d8b6ef339c8@linaro.org?part=3