Re: [PATCH 3/3] cacheinfo: Add use_arch[|_cache]_info field/function

Pierre Gondois
2023-04-06T07:29:44Z

Hello Will,

On 3/27/23 14:17, Will Deacon wrote:
> On Mon, Mar 27, 2023 at 01:59:51PM +0200, Pierre Gondois wrote:
>> The cache information can be extracted from either a Device
>> Tree (DT), the PPTT ACPI table, or arch registers (clidr_el1
>> for arm64).
>>
>> The clidr_el1 register is used only if DT/ACPI information is not
>> available. It does not states how caches are shared among CPUs.
>>
>> Add a use_arch_cache_info field/function to identify when the
>> DT/ACPI doesn't provide cache information. Use this information
>> to assume L1 caches are privates and L2 and higher are shared among
>> all CPUs.
>>
>> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
>> ---
>> arch/arm64/kernel/cacheinfo.c | 5 +++++
>> drivers/base/cacheinfo.c | 20 ++++++++++++++++++--
>> include/linux/cacheinfo.h | 2 ++
>> 3 files changed, 25 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
>> index c307f69e9b55..b6306cda0fa7 100644
>> --- a/arch/arm64/kernel/cacheinfo.c
>> +++ b/arch/arm64/kernel/cacheinfo.c
>> @@ -96,3 +96,8 @@ int populate_cache_leaves(unsigned int cpu)
>> }
>> return 0;
>> }
>> +
>> +bool use_arch_cache_info(unsigned int cpu)
>> +{
>> + return true;
>> +}
>
> It would be a lot nicer if this was a static inline function in a header
> rather than a weak symbol.

I am not sure I see where the static inline function should be added.
Do you prefer to have function like the following in
include/linux/cacheinfo.h ?

static inline bool use_arch_cache_info(unsigned int cpu)
{
#if defined(CONFIG_ARM64)
return true;
#else
return false;
#endif
}

Regards,
Pierre

>
> Will