linux-kernel - Re: [PATCH V2] perf cs-etm: Add fix for coresight trace for any range of CPUs

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Message-ID: <ZEx5n8MdwuV5JE2r@kernel.org>
Date:   Fri, 28 Apr 2023 22:57:51 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        mike.leach@...aro.org, suzuki.poulose@....com,
        mathieu.poirier@...aro.org, darren@...amperecomputing.com,
        scott@...amperecomputing.com, scclevenger@...amperecomputing.com
Subject: Re: [PATCH V2] perf cs-etm: Add fix for coresight trace for any
 range of CPUs

Em Thu, Apr 20, 2023 at 10:52:53PM -0700, Ganapatrao Kulkarni escreveu:
> The current implementation supports coresight trace decode for a range
> of CPUs, if the first CPU is CPU0.
> 
> Perf report segfaults, if tried for sparse CPUs list and also for
> any range of CPUs(non zero first CPU).
> 
> Adding a fix to perf report for any range of CPUs and for sparse list.

Can some ARM people please review this?

- Arnaldo
 
> Signed-off-by: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
> ---
> 
> V2:
> 	Updated with review comments.
> 	Fixed for sparse list of CPUs also.
> 
> V1:
> 	[1] https://lore.kernel.org/lkml/20230419172101.78638-1-gankulkarni@os.amperecomputing.com/
> 
>  tools/perf/util/cs-etm.c | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> index 8dd81ddd9e4e..2003717f5779 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -275,6 +275,25 @@ static int cs_etm__metadata_set_trace_id(u8 trace_chan_id, u64 *cpu_metadata)
>  		(typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
>  	})
>  
> +/*
> + * Get a metadata for a specific cpu from an array.
> + *
> + */
> +static u64 *get_cpu_data(struct cs_etm_auxtrace *etm, int cpu)
> +{
> +	int i;
> +	u64 *metadata = NULL;
> +
> +	for (i = 0; i < etm->num_cpu; i++) {
> +		if (etm->metadata[i][CS_ETM_CPU] == (u64)cpu) {
> +			metadata = etm->metadata[i];
> +			break;
> +		}
> +	}
> +
> +	return metadata;
> +}
> +
>  /*
>   * Handle the PERF_RECORD_AUX_OUTPUT_HW_ID event.
>   *
> @@ -344,8 +363,11 @@ static int cs_etm__process_aux_output_hw_id(struct perf_session *session,
>  		return 0;
>  	}
>  
> +	cpu_data = get_cpu_data(etm, cpu);
> +	if (cpu_data == NULL)
> +		return err;
> +
>  	/* not one we've seen before - lets map it */
> -	cpu_data = etm->metadata[cpu];
>  	err = cs_etm__map_trace_id(trace_chan_id, cpu_data);
>  	if (err)
>  		return err;
> -- 
> 2.39.2
> 

-- 

- Arnaldo