Hi Peter,
On Tue, Mar 23, 2021 at 12:06:32PM +0000, Suzuki K Poulose wrote:
> CoreSight PMU supports aux-buffer for the ETM tracing. The trace
> generated by the ETM (associated with individual CPUs, like Intel PT)
> is captured by a separate IP (CoreSight TMC-ETR/ETF until now).
>
> The TMC-ETR applies formatting of the raw ETM trace data, as it
> can collect traces from multiple ETMs, with the TraceID to indicate
> the source of a given trace packet.
>
> Arm Trace Buffer Extension is new "sink" IP, attached to individual
> CPUs and thus do not provide additional formatting, like TMC-ETR.
>
> Additionally, a system could have both TRBE *and* TMC-ETR for
> the trace collection. e.g, TMC-ETR could be used as a single
> trace buffer to collect data from multiple ETMs to correlate
> the traces from different CPUs. It is possible to have a
> perf session where some events end up collecting the trace
> in TMC-ETR while the others in TRBE. Thus we need a way
> to identify the type of the trace for each AUX record.
>
> Define the trace formats exported by the CoreSight PMU.
> We don't define the flags following the "ETM" as this
> information is available to the user when issuing
> the session. What is missing is the additional
> formatting applied by the "sink" which is decided
> at the runtime and the user may not have a control on.
>
> So we define :
> - CORESIGHT format (indicates the Frame format)
> - RAW format (indicates the format of the source)
>
> The default value is CORESIGHT format for all the records
> (i,e == 0). Add the RAW format for others that use
> raw format.
>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Mike Leach <mike.le...@linaro.org>
> Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
> Cc: Leo Yan <leo....@linaro.org>
> Cc: Anshuman Khandual <anshuman.khand...@arm.com>
> Reviewed-by: Mike Leach <mike.le...@linaro.org>
> Reviewed-by: Mathieu Poirier <mathieu.poir...@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
> ---
> include/uapi/linux/perf_event.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index f006eeab6f0e..63971eaef127 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -1162,6 +1162,10 @@ enum perf_callchain_context {
> #define PERF_AUX_FLAG_COLLISION 0x08 /* sample
> collided with another */
> #define PERF_AUX_FLAG_PMU_FORMAT_TYPE_MASK 0xff00 /* PMU specific trace
> format type */
>
> +/* CoreSight PMU AUX buffer formats */
> +#define PERF_AUX_FLAG_CORESIGHT_FORMAT_CORESIGHT 0x0000 /* Default for
> backward compatibility */
> +#define PERF_AUX_FLAG_CORESIGHT_FORMAT_RAW 0x0100 /* Raw format of
> the source */
> +
Have you had time to review this patch? Anything you'd like to see modified?
Thanks,
Mathieu
> #define PERF_FLAG_FD_NO_GROUP (1UL << 0)
> #define PERF_FLAG_FD_OUTPUT (1UL << 1)
> #define PERF_FLAG_PID_CGROUP (1UL << 2) /* pid=cgroup id, per-cpu
> mode only */
> --
> 2.24.1
>
