linux-kernel - [PATCH v2] coresight: etm4x: Modify core-commit of cpu to avoid the overflow of HiSilicon ETM

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Message-ID: <1600681842-9105-1-git-send-email-liuqi115@huawei.com>
Date:   Mon, 21 Sep 2020 17:50:42 +0800
From:   Qi Liu <liuqi115@...wei.com>
To:     <mathieu.poirier@...aro.org>, <suzuki.poulose@....com>,
        <Al.Grant@....com>, <mike.leach@...aro.org>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>
Subject: [PATCH v2] coresight: etm4x: Modify core-commit of cpu to avoid the overflow of HiSilicon ETM

The ETM device can't keep up with the core pipeline when cpu core
is at full speed. This may cause overflow within core and its ETM.
This is a common phenomenon on ETM devices.

On HiSilicon Hip08 platform, a specific feature is added to set
core pipeline. So commit rate can be reduced manually to avoid ETM
overflow.

Signed-off-by: Qi Liu <liuqi115@...wei.com>
---
Change since v1:
- add CONFIG_ETM4X_IMPDEF_FEATURE and CONFIG_ETM4X_IMPDEF_HISILICON
  to keep specific feature off platforms which don't use it.

 drivers/hwtracing/coresight/Kconfig           | 13 ++++++
 drivers/hwtracing/coresight/coresight-etm4x.c | 60 +++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index 02dbb5c..362dadf 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -85,6 +85,19 @@ config CORESIGHT_SOURCE_ETM4X
 	  for instruction level tracing. Depending on the implemented version
 	  data tracing may also be available.

+config ETM4X_IMPDEF_FEATURE
+	bool "Control overflow impdef support in CoreSight ETM 4.x driver "
+	depends on CORESIGHT_SOURCE_ETM4X
+	help
+	  This control provides overflow impdef for CoreSight ETM 4.x driver
+	  which can not reduce commit race automatically.
+
+config ETM4X_IMPDEF_HISILICON
+	bool "Control overflow impdef support in HiSilicon ETM 4.x driver "
+	depends on ETM4X_IMPDEF_FEATURE
+	help
+	  This control provides overflow impdef for HiSilicon ETM 4.x driver.
+
 config CORESIGHT_STM
 	bool "CoreSight System Trace Macrocell driver"
 	depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index f5ab13a..1a7a6c9 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -103,12 +103,71 @@ struct etm4_enable_arg {
 	int rc;
 };

+#ifdef CONFIG_ETM4X_IMPDEF_FEATURE
+
+#ifdef CONFIG_ETM4X_IMPDEF_HISILICON
+
+#define HISI_HIP08_CORE_COMMIT_CLEAR	0x3000
+#define HISI_HIP08_CORE_COMMIT_SHIFT	12
+static void etm4_hisi_config_core_commit(int flag)
+{
+	u64 val;
+
+	asm volatile("mrs %0,s3_1_c15_c2_5" : "=r"(val));
+	val &= ~HISI_HIP08_CORE_COMMIT_CLEAR;
+	val |= flag << HISI_HIP08_CORE_COMMIT_SHIFT;
+	asm volatile("msr s3_1_c15_c2_5,%0" : : "r"(val));
+}
+#else
+static void etm4_hisi_config_core_commit(int flag)
+{
+}
+#endif /* CONFIG_ETM4X_IMPDEF_HISILICON */
+
+static void etm4_enable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+	struct device *dev = drvdata->csdev->dev.parent;
+	struct amba_device *adev;
+
+	adev = container_of(dev, struct amba_device, dev);
+
+	/*
+	 * If ETM device is HiSilicon ETM device, reduce the
+	 * core-commit to avoid ETM overflow.
+	 */
+	etm4_hisi_config_core_commit(1);
+}
+
+static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+	struct device *dev = drvdata->csdev->dev.parent;
+	struct amba_device *adev;
+
+	adev = container_of(dev, struct amba_device, dev);
+
+	/*
+	 * If ETM device is HiSilicon ETM device, resume the
+	 * core-commit after ETM trace is complete.
+	 */
+	etm4_hisi_config_core_commit(0);
+}
+#else
+static void etm4_enable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+}
+
+static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+}
+#endif/* CONFIG_ETM4X_IMPDEF_FEATURE */
+
 static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 {
 	int i, rc;
 	struct etmv4_config *config = &drvdata->config;
 	struct device *etm_dev = &drvdata->csdev->dev;

+	etm4_enable_arch_specific(drvdata);
 	CS_UNLOCK(drvdata->base);

 	etm4_os_unlock(drvdata);
@@ -475,6 +534,7 @@ static void etm4_disable_hw(void *info)
 	struct device *etm_dev = &drvdata->csdev->dev;
 	int i;

+	etm4_disable_arch_specific(drvdata);
 	CS_UNLOCK(drvdata->base);

 	if (!drvdata->skip_power_up) {
--
2.8.1