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

Mathieu Poirier
2020-12-08T18:16:49Z

On Tue, Dec 08, 2020 at 03:19:20PM +0800, Qi Liu wrote:
> 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>

I have applied your patch after making modifications to the title and the
Kconfig description.

Thanks,
Mathieu

> ---
> 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
>