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From: Leo Yan <leo.yan@linaro.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mike Leach <mike.leach@linaro.org>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org
Cc: Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v4 02/11] coresight: tmc-etr: Add barrier after updating AUX ring buffer
Date: Sun, 11 Jul 2021 18:40:56 +0800	[thread overview]
Message-ID: <20210711104105.505728-3-leo.yan@linaro.org> (raw)
In-Reply-To: <20210711104105.505728-1-leo.yan@linaro.org>

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>
---
 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 acdb59e0e661..713205db15a1 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1563,6 +1563,14 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
 	 */
 	if (etr_perf->snapshot)
 		handle->head += size;
+
+	/*
+	 * It requires the ordering between the AUX trace data and aux_head
+	 * store, below smp_wmb() ensures the AUX trace data is visible prior
+	 * to updating aux_head.
+	 */
+	smp_wmb();
+
 out:
 	/*
 	 * Don't set the TRUNCATED flag in snapshot mode because 1) the
-- 
2.25.1


WARNING: multiple messages have this Message-ID (diff)
From: Leo Yan <leo.yan@linaro.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Mathieu Poirier <mathieu.poirier@linaro.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mike Leach <mike.leach@linaro.org>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org
Cc: Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v4 02/11] coresight: tmc-etr: Add barrier after updating AUX ring buffer
Date: Sun, 11 Jul 2021 18:40:56 +0800	[thread overview]
Message-ID: <20210711104105.505728-3-leo.yan@linaro.org> (raw)
In-Reply-To: <20210711104105.505728-1-leo.yan@linaro.org>

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>
---
 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 acdb59e0e661..713205db15a1 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1563,6 +1563,14 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
 	 */
 	if (etr_perf->snapshot)
 		handle->head += size;
+
+	/*
+	 * It requires the ordering between the AUX trace data and aux_head
+	 * store, below smp_wmb() ensures the AUX trace data is visible prior
+	 * to updating aux_head.
+	 */
+	smp_wmb();
+
 out:
 	/*
 	 * Don't set the TRUNCATED flag in snapshot mode because 1) the
-- 
2.25.1


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-07-11 10:41 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-11 10:40 [PATCH v4 00/11] perf: Refine barriers for AUX ring buffer Leo Yan
2021-07-11 10:40 ` Leo Yan
2021-07-11 10:40 ` [PATCH v4 01/11] perf/ring_buffer: Add comment for barriers on " Leo Yan
2021-07-11 10:40   ` Leo Yan
2021-07-11 10:40 ` Leo Yan [this message]
2021-07-11 10:40   ` [PATCH v4 02/11] coresight: tmc-etr: Add barrier after updating " Leo Yan
2021-07-12 10:40   ` Suzuki K Poulose
2021-07-12 10:40     ` Suzuki K Poulose
2021-07-12 10:54     ` Leo Yan
2021-07-12 10:54       ` Leo Yan
2021-07-11 10:40 ` [PATCH v4 03/11] coresight: tmc-etf: Add comment for store ordering Leo Yan
2021-07-11 10:40   ` Leo Yan
2021-07-13 12:56   ` Peter Zijlstra
2021-07-13 12:56     ` Peter Zijlstra
2021-07-13 15:49     ` Leo Yan
2021-07-13 15:49       ` Leo Yan
2021-07-11 10:40 ` [PATCH v4 04/11] perf/x86: Add barrier after updating bts Leo Yan
2021-07-11 10:40   ` Leo Yan
2021-07-13 13:01   ` Peter Zijlstra
2021-07-13 13:01     ` Peter Zijlstra
2021-07-11 10:40 ` [PATCH v4 05/11] perf auxtrace: Use WRITE_ONCE() for updating aux_tail Leo Yan
2021-07-11 10:40   ` Leo Yan
2021-07-11 10:41 ` [PATCH v4 06/11] perf auxtrace: Drop legacy __sync functions Leo Yan
2021-07-11 10:41   ` Leo Yan
2021-07-11 10:41 ` [PATCH v4 07/11] perf auxtrace: Remove auxtrace_mmap__read_snapshot_head() Leo Yan
2021-07-11 10:41   ` Leo Yan
2021-07-12 14:32   ` Adrian Hunter
2021-07-12 14:32     ` Adrian Hunter
2021-07-13 13:10     ` Leo Yan
2021-07-13 13:10       ` Leo Yan
2021-07-11 10:41 ` [PATCH v4 08/11] perf: Cleanup for HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT Leo Yan
2021-07-11 10:41   ` Leo Yan
2021-07-11 10:41 ` [PATCH v4 09/11] tools: Remove feature-sync-compare-and-swap feature detection Leo Yan
2021-07-11 10:41   ` Leo Yan
2021-07-11 10:41 ` [PATCH v4 10/11] perf env: Set flag for kernel is 64-bit mode Leo Yan
2021-07-11 10:41   ` Leo Yan
2021-07-12 14:37   ` Adrian Hunter
2021-07-12 14:37     ` Adrian Hunter
2021-07-12 18:14   ` Arnaldo Carvalho de Melo
2021-07-12 18:14     ` Arnaldo Carvalho de Melo
2021-07-13 15:09     ` Leo Yan
2021-07-13 15:09       ` Leo Yan
2021-07-13 17:31       ` Hunter, Adrian
2021-07-13 17:31         ` Hunter, Adrian
2021-07-14 13:59         ` Arnaldo Carvalho de Melo
2021-07-14 13:59           ` Arnaldo Carvalho de Melo
2021-07-14 14:00           ` Arnaldo Carvalho de Melo
2021-07-14 14:00             ` Arnaldo Carvalho de Melo
2021-07-23  7:11             ` Leo Yan
2021-07-23  7:11               ` Leo Yan
2021-07-11 10:41 ` [PATCH v4 11/11] perf auxtrace: Add compat_auxtrace_mmap__{read_head|write_tail} Leo Yan
2021-07-11 10:41   ` Leo Yan
2021-07-12 14:44   ` Russell King (Oracle)
2021-07-12 14:44     ` Russell King (Oracle)
2021-07-13 15:46     ` Leo Yan
2021-07-13 15:46       ` Leo Yan
2021-07-13 16:14       ` Russell King (Oracle)
2021-07-13 16:14         ` Russell King (Oracle)
2021-07-13 18:13         ` Catalin Marinas
2021-07-13 18:13           ` Catalin Marinas
2021-07-14  8:40           ` Russell King (Oracle)
2021-07-14  8:40             ` Russell King (Oracle)
2021-07-23  7:23             ` Leo Yan
2021-07-23  7:23               ` Leo Yan
2021-07-13  7:07   ` Adrian Hunter
2021-07-13  7:07     ` Adrian Hunter
2021-07-13 15:48     ` Leo Yan
2021-07-13 15:48       ` Leo Yan

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