linux-kernel - Re: perf usage of arch/arm64/include/asm/cputype.h

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Message-ID: <2dc510b4-ff3d-edff-42be-f8260cd27840@huawei.com>
Date: Mon, 16 Jun 2025 23:04:08 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: Leo Yan <leo.yan@....com>, Shameerali Kolothum Thodi
	<shameerali.kolothum.thodi@...wei.com>
CC: <yangyicong@...ilicon.com>, James Clark <james.clark@...aro.org>, "Arnaldo
 Carvalho de Melo" <acme@...nel.org>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, Ali Saidi <alisaidi@...zon.com>, "Leo
 Yan" <leo.yan@...aro.org>, Will Deacon <will@...nel.org>, James Morse
	<james.morse@....com>, Catalin Marinas <catalin.marinas@....com>, yangjinqian
	<yangjinqian1@...wei.com>, Douglas Anderson <dianders@...omium.org>, "Dmitry
 Baryshkov" <dmitry.baryshkov@...aro.org>, Adrian Hunter
	<adrian.hunter@...el.com>, Ian Rogers <irogers@...gle.com>, Jiri Olsa
	<jolsa@...nel.org>, Kan Liang <kan.liang@...ux.intel.com>, Namhyung Kim
	<namhyung@...nel.org>, Linux Kernel Mailing List
	<linux-kernel@...r.kernel.org>
Subject: Re: perf usage of arch/arm64/include/asm/cputype.h

On 2025/6/16 21:07, Leo Yan wrote:
> On Mon, Jun 16, 2025 at 09:54:43AM +0000, Shameerali Kolothum Thodi wrote:
> 
> [...]
> 
>>>> -bool is_midr_in_range_list(struct midr_range const *ranges) -{
>>>> -	while (ranges->model)
>>>> -		if (is_midr_in_range(ranges++))
>>>> -			return true;
>>>>   	return false;
>>>>   }
> 
>>> Looks ok to me.
>>>
>>> You could do it with slightly less churn on the kernel side if you keep the
>>> function name and arguments the same there. There's only one usage in
>>> Perf so that one could be renamed and have the midr argument added back
>>> in.
>>
>> +1.
>>
>> Can we use a separate one for perf here, something like below(untested)?
> 
> Thanks for working on this. Agreed.
> 
>> --- a/tools/perf/util/arm-spe.c
>> +++ b/tools/perf/util/arm-spe.c
>> @@ -842,6 +842,18 @@ static void arm_spe__synth_memory_level(const
>> struct arm_spe_record *record,
>>                 data_src->mem_lvl |= PERF_MEM_LVL_REM_CCE1;
>>  }
>>
>> +static bool is_perf_midr_in_range_list(u32 midr, struct midr_range
>> const *ranges)
>> +{
>> +       while (ranges->model) {
>> +               if (midr_is_cpu_model_range(midr, ranges->model,
>> +                                           ranges->rv_min, ranges->rv_max)) {
>> +                       return true;
>> +               }
>> +               ranges++;
>> +       }
>> +       return false;
>> +}
> 
> Maybe we can make it more general. For example, move this function into
> a common header such as tools/perf/arch/arm64/include/cputype.h. Then,
> util/arm-spe.c can include this header.
> 

ok this sounds just like as before except rename the midr check function and modify the
users in perf. will do in below steps:
- move cpu_errata_set_target_impl()/is_midr_in_range_list() out of cputype.h
  since they're only used in the kernel with errata information
- introduce is_target_midr_in_range_list() in cputype.h to test certain MIDR
  is within the ranges. (is_perf_midr_in_range_list() only make sense in
  userspace and is a bit strange to me in a kernel header). maybe reimplement
  is_midr_in_range_list() with is_target_midr_in_range_list() otherwise there's
  no users in kernel
- copy cputype.h to userspace and make users use new is_target_midr_in_range_list()

this will avoid touching the kernel too much and userspace don't need to implement
a separate function.

Thanks.