RE: [PATCH v5 1/2] perf: arm_cspmu: Add support for ARM CoreSight PMU driver
From: Besar Wicaksono
Date: Thu Sep 29 2022 - 10:06:23 EST
Hi Suzuki,
> -----Original Message-----
> From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Sent: Thursday, September 29, 2022 3:29 AM
> To: Besar Wicaksono <bwicaksono@xxxxxxxxxx>; robin.murphy@xxxxxxx;
> catalin.marinas@xxxxxxx; will@xxxxxxxxxx; mark.rutland@xxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> linux-tegra@xxxxxxxxxxxxxxx; sudeep.holla@xxxxxxx;
> thanu.rangarajan@xxxxxxx; Michael.Williams@xxxxxxx; Thierry Reding
> <treding@xxxxxxxxxx>; Jonathan Hunter <jonathanh@xxxxxxxxxx>; Vikram
> Sethi <vsethi@xxxxxxxxxx>; mathieu.poirier@xxxxxxxxxx;
> mike.leach@xxxxxxxxxx; leo.yan@xxxxxxxxxx
> Subject: Re: [PATCH v5 1/2] perf: arm_cspmu: Add support for ARM
> CoreSight PMU driver
>
> External email: Use caution opening links or attachments
>
>
> Hi Besar
>
> On 28/09/2022 21:18, Besar Wicaksono wrote:
> > Add support for ARM CoreSight PMU driver framework and interfaces.
> > The driver provides generic implementation to operate uncore PMU based
> > on ARM CoreSight PMU architecture. The driver also provides interface
> > to get vendor/implementation specific information, for example event
> > attributes and formating.
> >
> > The specification used in this implementation can be found below:
> > * ACPI Arm Performance Monitoring Unit table:
> > https://developer.arm.com/documentation/den0117/latest
> > * ARM Coresight PMU architecture:
> > https://developer.arm.com/documentation/ihi0091/latest
> >
> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > Signed-off-by: Besar Wicaksono <bwicaksono@xxxxxxxxxx>
>
> Apologies for this late comment. Please find it below.
>
> > ---
> > arch/arm64/configs/defconfig | 1 +
> > drivers/perf/Kconfig | 2 +
> > drivers/perf/Makefile | 1 +
> > drivers/perf/arm_cspmu/Kconfig | 13 +
> > drivers/perf/arm_cspmu/Makefile | 6 +
> > drivers/perf/arm_cspmu/arm_cspmu.c | 1276
> ++++++++++++++++++++++++++++
> > drivers/perf/arm_cspmu/arm_cspmu.h | 151 ++++
> > 7 files changed, 1450 insertions(+)
> > create mode 100644 drivers/perf/arm_cspmu/Kconfig
> > create mode 100644 drivers/perf/arm_cspmu/Makefile
> > create mode 100644 drivers/perf/arm_cspmu/arm_cspmu.c
> > create mode 100644 drivers/perf/arm_cspmu/arm_cspmu.h
> >
> > diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
> > index 7d1105343bc2..ee31c9159a5b 100644
> > --- a/arch/arm64/configs/defconfig
> > +++ b/arch/arm64/configs/defconfig
> > @@ -1212,6 +1212,7 @@ CONFIG_PHY_UNIPHIER_USB3=y
> > CONFIG_PHY_TEGRA_XUSB=y
> > CONFIG_PHY_AM654_SERDES=m
> > CONFIG_PHY_J721E_WIZ=m
> > +CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU=y
> > CONFIG_ARM_SMMU_V3_PMU=m
> > CONFIG_FSL_IMX8_DDR_PMU=m
> > CONFIG_QCOM_L2_PMU=y
> > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > index 1e2d69453771..c94d3601eb48 100644
> > --- a/drivers/perf/Kconfig
> > +++ b/drivers/perf/Kconfig
> > @@ -192,4 +192,6 @@ config MARVELL_CN10K_DDR_PMU
> > Enable perf support for Marvell DDR Performance monitoring
> > event on CN10K platform.
> >
> > +source "drivers/perf/arm_cspmu/Kconfig"
> > +
> > endmenu
> > diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> > index 57a279c61df5..3bc9323f0965 100644
> > --- a/drivers/perf/Makefile
> > +++ b/drivers/perf/Makefile
> > @@ -20,3 +20,4 @@ obj-$(CONFIG_ARM_DMC620_PMU) +=
> arm_dmc620_pmu.o
> > obj-$(CONFIG_MARVELL_CN10K_TAD_PMU) +=
> marvell_cn10k_tad_pmu.o
> > obj-$(CONFIG_MARVELL_CN10K_DDR_PMU) +=
> marvell_cn10k_ddr_pmu.o
> > obj-$(CONFIG_APPLE_M1_CPU_PMU) += apple_m1_cpu_pmu.o
> > +obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) +=
> arm_cspmu/
> > diff --git a/drivers/perf/arm_cspmu/Kconfig
> b/drivers/perf/arm_cspmu/Kconfig
> > new file mode 100644
> > index 000000000000..c2c56ecafccb
> > --- /dev/null
> > +++ b/drivers/perf/arm_cspmu/Kconfig
> > @@ -0,0 +1,13 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +#
> > +# Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES.
> > +
> > +config ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU
> > + tristate "ARM Coresight Architecture PMU"
> > + depends on ACPI
> > + depends on ACPI_APMT || COMPILE_TEST
> > + help
> > + Provides support for performance monitoring unit (PMU) devices
> > + based on ARM CoreSight PMU architecture. Note that this PMU
> > + architecture does not have relationship with the ARM CoreSight
> > + Self-Hosted Tracing.
> > diff --git a/drivers/perf/arm_cspmu/Makefile
> b/drivers/perf/arm_cspmu/Makefile
> > new file mode 100644
> > index 000000000000..cdc3455f74d8
> > --- /dev/null
> > +++ b/drivers/perf/arm_cspmu/Makefile
> > @@ -0,0 +1,6 @@
> > +# Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES.
> > +#
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += \
> > + arm_cspmu.o
> > diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c
> b/drivers/perf/arm_cspmu/arm_cspmu.c
> > new file mode 100644
> > index 000000000000..0fa5f29bf1c6
> > --- /dev/null
> > +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
> > @@ -0,0 +1,1276 @@
>
>
> > +/* Default event list. */
> > +static struct attribute *arm_cspmu_event_attrs[] = {
> > + ARM_CSPMU_EVENT_ATTR(cycles,
> ARM_CSPMU_EVT_CYCLES_DEFAULT),
> > + NULL,
> > +};
> > +
> > +static struct attribute **
> > +arm_cspmu_get_event_attrs(const struct arm_cspmu *cspmu)
> > +{
> > + return arm_cspmu_event_attrs;
> > +}
>
> This would make all the "PMU" instances (which don't implement the
> callback) share a non-const array. Could we instead return a copy of
> the attrs to avoid drivers messing up with the array ?
> The array could be allocated via devm_ on the specific device, thus
> it gets cleaned up on the device tear down ?
>
> ...
>
> > +static struct attribute **
> > +arm_cspmu_get_format_attrs(const struct arm_cspmu *cspmu)
> > +{
> > + return arm_cspmu_format_attrs;
> > +}
> > +
>
> Same as above
I was expecting the vendor specific impl to be aware and make its own
copy if it needs to make modifications to the array. But I can return a copy
to be on the safe side. We can revisit again if it is unnecessary.
I will send the updated patch shortly.
Thanks,
Besar
>
> Suzuki