Re: [PATCH v2] perf/arm_cspmu: Add Arm system PMU

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] arm_syspmu: build failure on 32-bit archs due to missing writeq fallback
--

commit ee9850d17fe1852cb671454c79f2ae56292d6550
Author: Robin Murphy <robin.murphy@arm.com>

perf/arm_cspmu: Add Arm system PMU

Arm's latest Compute Subsystems and SoCs are using a common PMU block
in various places which can mostly just be driven as a generic 64-bit
CoreSight PMU, but does have an IMP-DEF register for additional
filtering. The details of event and filter encodings depend on the
particular PMU instance, so are left to the higher level Arm Telemetry
Solution tooling.

> diff --git a/drivers/perf/arm_cspmu/arm_syspmu.c b/drivers/perf/arm_cspmu/arm_syspmu.c
> new file mode 100644
> index 0000000000000..ac234768a2f80
> --- /dev/null
> +++ b/drivers/perf/arm_cspmu/arm_syspmu.c
> @@ -0,0 +1,67 @@

[ ... ]

> +static void arm_syspmu_set_ev_filter(struct arm_cspmu *cspmu,
> +				     const struct perf_event *event)
> +{
> +	u32 offset = 8 * event->hw.idx;
> +
> +	writeq(event->attr.config1, cspmu->base0 + PMEVFILTR + offset);
> +	writeq(event->attr.config2, cspmu->base0 + PMEVFILT2R + offset);
> +	writeq(event->attr.config3, cspmu->base0 + PMEVFILT3R + offset);

[Severity: Low]
Will this driver fail to build on 32-bit architectures?

When compiling with CONFIG_COMPILE_TEST=y on a 32-bit platform like i386 or
ARM32, writeq() is not natively defined.

Could we include <linux/io-64-nonatomic-lo-hi.h> to ensure the driver
compiles successfully by providing a writeq() fallback for 32-bit builds?

> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/162173d376d223941b0c8b4e4a1c9ad2ae5c11a3.1791207773.git.robin.murphy@arm.com?part=1