Commit 26701ceb authored by Leo Yan's avatar Leo Yan Committed by Mathieu Poirier
Browse files

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: default avatarLeo Yan <leo.yan@linaro.org>
Reviewed-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20210809111407.596077-3-leo.yan@linaro.org


Signed-off-by: default avatarSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
parent 4d5d88ba

drivers/hwtracing/coresight/coresight-tmc-etr.c

+8 −0
Original line number Diff line number Diff line
@@ -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