Re: [PATCH 1/4] pkeys: add API to switch to permissive pkey register

[Dave Hansen <dave.hansen@intel.com>]

On 2/24/25 05:25, Dmitry Vyukov wrote:
>>> +#ifndef CONFIG_ARCH_HAS_PERMISSIVE_PKEY
>>> +
>>> +/*
>>> + * Common name for value of the register that controls access to PKEYs
>>> + * (called differently on different arches: PKRU, POR, AMR).
>>> + */
>>> +typedef int pkey_reg_t;
>> Tiny nit: Should this be an unsigned type?
>>
>> Nobody should be manipulating it, but I'd be surprised if any of the
>> architectures have a signed type for it.
> Since this is a stub type, can matching the real types do any good
> besides masking programming errors?
> I've changed it to char in v4 to surface more potential programming errors.

I was more worried about copy-and-paste.

I agree that 'char' is the most fragile, but it's going to fragile in
subtle ways and I'm not sure subtly broken code (whether it's expected
to be compiled in or not) is great to have in a code base.

Do we have any types in sparse that would be appropriate? Could we mark
the pkey_reg_t as being in a different address space when pkeys is
compiled out so that sparse knows not to let it interact with other types?