[PATCH v6] coresight: etm4x: Modify core-commit of cpu to avoid the overflow of HiSilicon ETM

* [PATCH v6] coresight: etm4x: Modify core-commit of cpu to avoid the overflow of HiSilicon ETM
@ 2020-12-08  7:19 Qi Liu
  2020-12-08 18:15 ` Mathieu Poirier
  0 siblings, 1 reply; 2+ messages in thread
From: Qi Liu @ 2020-12-08  7:19 UTC (permalink / raw)
  To: mathieu.poirier, suzuki.poulose, mike.leach
  Cc: coresight, linux-kernel, linux-arm-kernel, linuxarm

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.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Qi Liu <liuqi115@huawei.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.
Change since v2:
- remove some unused variable.
Change since v3:
- use read/write_sysreg_s() to access register.
Change since v4:
- rename the call back function to a more generic name, and fix some
  compile warnings.
Change since v5:
- add function comments about HISI_HIP08_CORE_COMMIT_REG, and use
  explicitly masked values when update register.

 drivers/hwtracing/coresight/Kconfig                |  9 ++
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 98 ++++++++++++++++++++++
 drivers/hwtracing/coresight/coresight-etm4x.h      |  8 ++
 3 files changed, 115 insertions(+)

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index c119824..1cc3601 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -110,6 +110,15 @@ config CORESIGHT_SOURCE_ETM4X
 	  To compile this driver as a module, choose M here: the
 	  module will be called coresight-etm4x.

+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 implement define for CoreSight
+	  ETM 4.x tracer module which could not reduce commit race
+	  automatically, and could avoid overflow within ETM tracer module
+	  and its cpu core.
+
 config CORESIGHT_STM
 	tristate "CoreSight System Trace Macrocell driver"
 	depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) || ARM64
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index abd706b..0cbc92a 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2014, The Linux Foundation. All rights reserved.
  */

+#include <linux/bitops.h>
 #include <linux/kernel.h>
 #include <linux/moduleparam.h>
 #include <linux/init.h>
@@ -28,7 +29,9 @@
 #include <linux/perf_event.h>
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
+
 #include <asm/sections.h>
+#include <asm/sysreg.h>
 #include <asm/local.h>
 #include <asm/virt.h>

@@ -103,6 +106,97 @@ struct etm4_enable_arg {
 	int rc;
 };

+#ifdef CONFIG_ETM4X_IMPDEF_FEATURE
+
+#define HISI_HIP08_AMBA_ID		0x000b6d01
+#define ETM4_AMBA_MASK			0xfffff
+#define HISI_HIP08_CORE_COMMIT_MASK	0x3000
+#define HISI_HIP08_CORE_COMMIT_SHIFT	12
+#define HISI_HIP08_CORE_COMMIT_FULL	0b00
+#define HISI_HIP08_CORE_COMMIT_LVL_1	0b01
+#define HISI_HIP08_CORE_COMMIT_REG	sys_reg(3, 1, 15, 2, 5)
+
+struct etm4_arch_features {
+	void (*arch_callback)(bool enable);
+};
+
+static bool etm4_hisi_match_pid(unsigned int id)
+{
+	return (id & ETM4_AMBA_MASK) == HISI_HIP08_AMBA_ID;
+}
+
+static void etm4_hisi_config_core_commit(bool enable)
+{
+	u8 commit = enable ? HISI_HIP08_CORE_COMMIT_LVL_1 :
+		    HISI_HIP08_CORE_COMMIT_FULL;
+	u64 val;
+
+	/*
+	 * bit 12 and 13 of HISI_HIP08_CORE_COMMIT_REG are used together
+	 * to set core-commit, 2'b00 means cpu is at full speed, 2'b01,
+	 * 2'b10, 2'b11 mean reduce pipeline speed, and 2'b01 means level-1
+	 * speed(minimun value). So bit 12 and 13 should be cleared together.
+	 */
+	val = read_sysreg_s(HISI_HIP08_CORE_COMMIT_REG);
+	val &= ~HISI_HIP08_CORE_COMMIT_MASK;
+	val |= commit << HISI_HIP08_CORE_COMMIT_SHIFT;
+	write_sysreg_s(val, HISI_HIP08_CORE_COMMIT_REG);
+}
+
+static struct etm4_arch_features etm4_features[] = {
+	[ETM4_IMPDEF_HISI_CORE_COMMIT] = {
+		.arch_callback = etm4_hisi_config_core_commit,
+	},
+	{},
+};
+
+static void etm4_enable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+	struct etm4_arch_features *ftr;
+	int bit;
+
+	for_each_set_bit(bit, drvdata->arch_features, ETM4_IMPDEF_FEATURE_MAX) {
+		ftr = &etm4_features[bit];
+
+		if (ftr->arch_callback)
+			ftr->arch_callback(true);
+	}
+}
+
+static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+	struct etm4_arch_features *ftr;
+	int bit;
+
+	for_each_set_bit(bit, drvdata->arch_features, ETM4_IMPDEF_FEATURE_MAX) {
+		ftr = &etm4_features[bit];
+
+		if (ftr->arch_callback)
+			ftr->arch_callback(false);
+	}
+}
+
+static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
+				      unsigned int id)
+{
+	if (etm4_hisi_match_pid(id))
+		set_bit(ETM4_IMPDEF_HISI_CORE_COMMIT, drvdata->arch_features);
+}
+#else
+static void etm4_enable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+}
+
+static void etm4_disable_arch_specific(struct etmv4_drvdata *drvdata)
+{
+}
+
+static void etm4_check_arch_features(struct etmv4_drvdata *drvdata,
+				     unsigned int id)
+{
+}
+#endif /* CONFIG_ETM4X_IMPDEF_FEATURE */
+
 static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 {
 	int i, rc;
@@ -110,6 +204,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata)
 	struct device *etm_dev = &drvdata->csdev->dev;

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

 	etm4_os_unlock(drvdata);

@@ -476,6 +571,7 @@ static void etm4_disable_hw(void *info)
 	int i;

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

 	if (!drvdata->skip_power_up) {
 		/* power can be removed from the trace unit now */
@@ -1547,6 +1643,8 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
 		drvdata->boot_enable = true;
 	}

+	etm4_check_arch_features(drvdata, id->id);
+
 	return 0;
 }

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index eefc737..3dd3e06 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -8,6 +8,7 @@

 #include <asm/local.h>
 #include <linux/spinlock.h>
+#include <linux/types.h>
 #include "coresight-priv.h"

 /*
@@ -203,6 +204,11 @@
 /* Interpretation of resource numbers change at ETM v4.3 architecture */
 #define ETM4X_ARCH_4V3	0x43

+enum etm_impdef_type {
+	ETM4_IMPDEF_HISI_CORE_COMMIT,
+	ETM4_IMPDEF_FEATURE_MAX,
+};
+
 /**
  * struct etmv4_config - configuration information related to an ETMv4
  * @mode:	Controls various modes supported by this ETM.
@@ -415,6 +421,7 @@ struct etmv4_save_state {
  * @state_needs_restore: True when there is context to restore after PM exit
  * @skip_power_up: Indicates if an implementation can skip powering up
  *		   the trace unit.
+ * @arch_features: Bitmap of arch features of etmv4 devices.
  */
 struct etmv4_drvdata {
 	void __iomem			*base;
@@ -463,6 +470,7 @@ struct etmv4_drvdata {
 	struct etmv4_save_state		*save_state;
 	bool				state_needs_restore;
 	bool				skip_power_up;
+	DECLARE_BITMAP(arch_features, ETM4_IMPDEF_FEATURE_MAX);
 };

 /* Address comparator access types */
--
2.8.1


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