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Fri, 16 Oct 2026 03:18:45 -0700 (PDT) Message-ID: <53999f08-bbfb-462e-8521-383aba65f2a9@linaro.org> Date: Fri, 16 Oct 2026 11:18:44 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] perf: Order SPE and TRBE padding before publishing AUX head To: Leo Yan Cc: linux-arm-kernel@lists.infradead.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org, Will Deacon , Mark Rutland , Suzuki K Poulose , Mike Leach , Alexander Shishkin , Anshuman Khandual , Mathieu Poirier References: <20261015-add_barriers_for_perf_aux_output_skip-v1-0-5847d0578859@arm.com> Content-Language: en-US From: James Clark In-Reply-To: <20261015-add_barriers_for_perf_aux_output_skip-v1-0-5847d0578859@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 15/10/2026 16:51, Leo Yan wrote: > SPE and TRBE write padding into their AUX buffers before advancing > aux_head. Add the missing write barriers so that a userspace reader on > another CPU cannot observe the new head before the padding stores > become visible. > > AUX producers must make their data visible before publishing aux_head. > The required synchronization depends on the trace hardware and CPU > memory model, so the barriers belong in the drivers rather than in > perf_aux_output_skip() or perf_aux_output_end(). The TRBE change also > covers padding inserted by the overwrite erratum workaround before > perf_aux_output_end(). > > Signed-off-by: Leo Yan > --- > Leo Yan (2): > perf: arm_spe: Order padding before publishing AUX head > coresight: trbe: Order padding before publishing AUX head > > drivers/hwtracing/coresight/coresight-trbe.c | 2 ++ > drivers/perf/arm_spe_pmu.c | 5 ++++- > 2 files changed, 6 insertions(+), 1 deletion(-) > --- > base-commit: 0fcb05b72344f40806cbe810de8872f1698bf053 > change-id: 20261015-add_barriers_for_perf_aux_output_skip-70356815b2bd > > Best regards, Reviewed-by: James Clark