On Fri, Dec 15, 2023 at 03:00:38PM +0000, James Clark wrote:
> LLVM ignores everything inside the if statement and doesn't generate
> errors, but GCC doesn't ignore it, resulting in the following error:
>
> drivers/perf/arm_pmuv3.c: In function 'armv8pmu_write_evtype':
> include/linux/bits.h:34:29: error: left shift count >= width of type [-Werror=shift-count-overflow]
> 34 | (((~UL(0)) - (UL(1) << (l)) + 1) & \
>
> Fix it by changing the if to #if.
I reckon it'd be cleaner to use GENMASK_ULL for the TH and TC fields, in
include/linux/perf/arm_pmu.h have:
| /*
| * PMXEVTYPER: Event selection reg
| */
| #define ARMV8_PMU_EVTYPE_EVENT GENMASK(15, 0) /* Mask for EVENT bits */
| #define ARMV8_PMU_EVTYPE_TH GENMASK_ULL(43, 32) /* arm64 only */
| #define ARMV8_PMU_EVTYPE_TC GENMASK_ULL(63, 61) /* arm64 only */
IIUC that should silence this warning, and it'd remove the need for the
ifdeffery and other changes in patch 2.
Does that work, or am I missing something?
Thanks,
Mark.
>
> Fixes: 3115ee021bfb ("arm64: perf: Include threshold control fields in PMEVTYPER mask")
> Reported-by: Uwe Kleine-K"onig <u.kleine-koenig@xxxxxxxxxxxxxx>
> Closes: https://lore.kernel.org/linux-arm-kernel/20231215120817.h2f3akgv72zhrtqo@xxxxxxxxxxxxxx/
> Signed-off-by: James Clark <james.clark@xxxxxxx>
> ---
> drivers/perf/arm_pmuv3.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
> index 23fa6c5da82c..3ed2086cefc3 100644
> --- a/drivers/perf/arm_pmuv3.c
> +++ b/drivers/perf/arm_pmuv3.c
> @@ -631,8 +631,9 @@ static void armv8pmu_write_evtype(int idx, unsigned long val)
> ARMV8_PMU_EXCLUDE_EL0 |
> ARMV8_PMU_EXCLUDE_EL1;
>
> - if (IS_ENABLED(CONFIG_ARM64))
> - mask |= ARMV8_PMU_EVTYPE_TC | ARMV8_PMU_EVTYPE_TH;
> +#if IS_ENABLED(CONFIG_ARM64)
> + mask |= ARMV8_PMU_EVTYPE_TC | ARMV8_PMU_EVTYPE_TH;
> +#endif
>
> val &= mask;
> write_pmevtypern(counter, val);
> --
> 2.34.1
>
