[PATCH] driver: perf: arm_pmuv3: Identify 'event->attr.config1' based attributes

[PATCH] driver: perf: arm_pmuv3: Identify 'event->attr.config1' based attributes

[Anshuman Khandual]

This defines macros to identify long and rdpmc attributes which get carried
inside 'event->attr.config1', thus making the code explicit and clear.

Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
This applies on v6.6-rc5.

 drivers/perf/arm_pmuv3.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index 94723d00548e..797ffd5a8fed 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -298,16 +298,19 @@ PMU_FORMAT_ATTR(event, "config:0-15");
 PMU_FORMAT_ATTR(long, "config1:0");
 PMU_FORMAT_ATTR(rdpmc, "config1:1");
 
+#define ARM_PMUV3_ATTR_LONG	0x01
+#define ARM_PMUV3_ATTR_RDPMC	0x02
+
 static int sysctl_perf_user_access __read_mostly;
 
 static inline bool armv8pmu_event_is_64bit(struct perf_event *event)
 {
-	return event->attr.config1 & 0x1;
+	return event->attr.config1 & ARM_PMUV3_ATTR_LONG;
 }
 
 static inline bool armv8pmu_event_want_user_access(struct perf_event *event)
 {
-	return event->attr.config1 & 0x2;
+	return event->attr.config1 & ARM_PMUV3_ATTR_RDPMC;
 }
 
 static struct attribute *armv8_pmuv3_format_attrs[] = {
-- 
2.25.1

Re: [PATCH] driver: perf: arm_pmuv3: Identify 'event->attr.config1' based attributes

[Mark Rutland]

On Mon, Oct 09, 2023 at 10:47:53AM +0530, Anshuman Khandual wrote:
> This defines macros to identify long and rdpmc attributes which get carried
> inside 'event->attr.config1', thus making the code explicit and clear.
> 
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> This applies on v6.6-rc5.
> 
>  drivers/perf/arm_pmuv3.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)

I think this would make sense to do if we also used a common definition of
these bits in the helper functions *and* their format attributes, but as-is
this does nothing to relate the two, and I don't think that it improves
legibility on its own.

Mark.

> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
> index 94723d00548e..797ffd5a8fed 100644
> --- a/drivers/perf/arm_pmuv3.c
> +++ b/drivers/perf/arm_pmuv3.c
> @@ -298,16 +298,19 @@ PMU_FORMAT_ATTR(event, "config:0-15");
>  PMU_FORMAT_ATTR(long, "config1:0");
>  PMU_FORMAT_ATTR(rdpmc, "config1:1");
>  
> +#define ARM_PMUV3_ATTR_LONG	0x01
> +#define ARM_PMUV3_ATTR_RDPMC	0x02
> +
>  static int sysctl_perf_user_access __read_mostly;
>  
>  static inline bool armv8pmu_event_is_64bit(struct perf_event *event)
>  {
> -	return event->attr.config1 & 0x1;
> +	return event->attr.config1 & ARM_PMUV3_ATTR_LONG;
>  }
>  
>  static inline bool armv8pmu_event_want_user_access(struct perf_event *event)
>  {
> -	return event->attr.config1 & 0x2;
> +	return event->attr.config1 & ARM_PMUV3_ATTR_RDPMC;
>  }
>  
>  static struct attribute *armv8_pmuv3_format_attrs[] = {
> -- 
> 2.25.1
> 

Re: [PATCH] driver: perf: arm_pmuv3: Identify 'event->attr.config1' based attributes

[Anshuman Khandual]

On 10/13/23 19:17, Mark Rutland wrote:
> On Mon, Oct 09, 2023 at 10:47:53AM +0530, Anshuman Khandual wrote:
>> This defines macros to identify long and rdpmc attributes which get carried
>> inside 'event->attr.config1', thus making the code explicit and clear.
>>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> This applies on v6.6-rc5.
>>
>>  drivers/perf/arm_pmuv3.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)

I am not sure, if I understand your concerns and/or suggestions properly.

> 
> I think this would make sense to do if we also used a common definition of
> these bits in the helper functions *and* their format attributes, but as-is

Common definitions of sysfs formats ? Which helper - linux/perf/arm_pmuv3.h ?

> this does nothing to relate the two, and I don't think that it improves
> legibility on its own.

Currently armv8pmu_event_is_64bit() and armv8pmu_event_want_user_access()
extracts required values from 'event->attr.config1' with hard coded masks
without any explicit co-relation with PMU_FORMAT_ATTR() described formats
above, unless some one really looks into the config1 bits layout.

Could you please provide some more details on how to go about making this
change better.

> 
> Mark.
> 
>> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
>> index 94723d00548e..797ffd5a8fed 100644
>> --- a/drivers/perf/arm_pmuv3.c
>> +++ b/drivers/perf/arm_pmuv3.c
>> @@ -298,16 +298,19 @@ PMU_FORMAT_ATTR(event, "config:0-15");
>>  PMU_FORMAT_ATTR(long, "config1:0");
>>  PMU_FORMAT_ATTR(rdpmc, "config1:1");
>>  
>> +#define ARM_PMUV3_ATTR_LONG	0x01
>> +#define ARM_PMUV3_ATTR_RDPMC	0x02
>> +
>>  static int sysctl_perf_user_access __read_mostly;
>>  
>>  static inline bool armv8pmu_event_is_64bit(struct perf_event *event)
>>  {
>> -	return event->attr.config1 & 0x1;
>> +	return event->attr.config1 & ARM_PMUV3_ATTR_LONG;
>>  }
>>  
>>  static inline bool armv8pmu_event_want_user_access(struct perf_event *event)
>>  {
>> -	return event->attr.config1 & 0x2;
>> +	return event->attr.config1 & ARM_PMUV3_ATTR_RDPMC;
>>  }
>>  
>>  static struct attribute *armv8_pmuv3_format_attrs[] = {
>> -- 
>> 2.25.1
>>