From 26701ceb4c2c6bfa5f8c8984fa1a1ea08fa0f02c Mon Sep 17 00:00:00 2001 From: Leo Yan <leo.yan@linaro.org> Date: Mon, 9 Aug 2021 19:14:00 +0800 Subject: [PATCH] coresight: tmc-etr: Add barrier after updating AUX ring buffer Since a memory barrier is required between AUX trace data store and aux_head store, and the AUX trace data is filled with memcpy(), it's sufficient to use smp_wmb() so can ensure the trace data is visible prior to updating aux_head. Signed-off-by: Leo Yan <leo.yan@linaro.org> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Link: https://lore.kernel.org/r/20210809111407.596077-3-leo.yan@linaro.org Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index 0ac2a611110bb..7f4654b723146 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -1564,6 +1564,14 @@ tmc_update_etr_buffer(struct coresight_device *csdev, */ if (etr_perf->snapshot) handle->head += size; + + /* + * Ensure that the AUX trace data is visible before the aux_head + * is updated via perf_aux_output_end(), as expected by the + * perf ring buffer. + */ + smp_wmb(); + out: /* * Don't set the TRUNCATED flag in snapshot mode because 1) the -- 2.30.2