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

Qi Liu
2020-12-08T07:22:16Z

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