On 15/12/2023 16:21, Mark Rutland wrote:
> 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.
>
You're right that does work. For some reason I thought there was some
component of writing it to the mask that was the issue as well.
I'll send another version with that fix instead.
Thanks
James
>>
>> 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
>>
