linux-kernel - Re: [PATCH 11/19] coresight: trbe: Apply overwrite erratum for only wrap event

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Message-ID: <cca13ee6-83d9-4478-ace0-1e7bedf79d0e@arm.com>
Date: Tue, 2 Dec 2025 12:05:52 +0000
From: Suzuki K Poulose <suzuki.poulose@....com>
To: Leo Yan <leo.yan@....com>, Mike Leach <mike.leach@...aro.org>,
 James Clark <james.clark@...aro.org>,
 Anshuman Khandual <anshuman.khandual@....com>,
 Yeoreum Yun <yeoreum.yun@....com>, Will Deacon <will@...nel.org>,
 Mark Rutland <mark.rutland@....com>, Tamas Petz <tamas.petz@....com>,
 Tamas Zsoldos <tamas.zsoldos@....com>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Namhyung Kim <namhyung@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
 Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 11/19] coresight: trbe: Apply overwrite erratum for only
 wrap event

On 01/12/2025 11:22, Leo Yan wrote:
> The overwrite erratum occurs only on wrap events, so apply the extra
> wrap condition check in the workaround.
> 
> Signed-off-by: Leo Yan <leo.yan@....com>
> ---
>   drivers/hwtracing/coresight/coresight-trbe.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index e579ea98523c24d23a0cd265dcdd0a46b52b52da..2600af12a8fb94bb8c74efda2a101aacd01b0b34 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -714,7 +714,7 @@ static unsigned long trbe_get_trace_size(struct perf_output_handle *handle,
>   	 * 64bytes. Thus we ignore the potential triggering of the erratum
>   	 * on WRAP and limit the data to LIMIT.
>   	 */
> -	if (wrap)
> +	if (wrap && trbe_may_overwrite_in_fill_mode(buf->cpudata))
>   		write = get_trbe_limit_pointer();

This must be trbe_may_write_out_of_range() ?

Suzuki


>   	else
>   		write = get_trbe_write_pointer();
> @@ -736,7 +736,7 @@ static unsigned long trbe_get_trace_size(struct perf_output_handle *handle,
>   	 * the space we skipped with IGNORE packets. And we are always
>   	 * guaranteed to have at least a PAGE_SIZE space in the buffer.
>   	 */
> -	if (trbe_may_overwrite_in_fill_mode(buf->cpudata) &&
> +	if (wrap && trbe_may_overwrite_in_fill_mode(buf->cpudata) &&
>   	    !WARN_ON(size < overwrite_skip))
>   		__trbe_pad_buf(buf, start_off, overwrite_skip);
>   
>