[RFC v7 16/25] powerpc: helper to validate key-access permissions of a pte

[Michael Ellerman]

Ram Pai <linuxram at us.ibm.com> writes:
> On Wed, Oct 18, 2017 at 06:08:34PM +0200, Laurent Dufour wrote:
>> On 31/07/2017 02:12, Ram Pai wrote:
>> > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
>> > index 4b7e3f4..ba7bff6 100644
>> > --- a/arch/powerpc/include/asm/pkeys.h
>> > +++ b/arch/powerpc/include/asm/pkeys.h
>> > @@ -85,6 +85,18 @@ static inline u64 pte_to_hpte_pkey_bits(u64 pteflags)
>> >  		((pteflags & H_PAGE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL));
>> >  }
>> > 
>> > +static inline u16 pte_to_pkey_bits(u64 pteflags)
>> > +{
>> > +	if (!pkey_inited)
>> > +		return 0x0UL;
>> 
>> Is it really needed to make such a check in this low level function ?
>> The only caller is already checking for pkey_inited before making the call.
>
> There are two callers to this function. get_pte_pkey() is one among
> them and it calls this function ignorant of the status of the
> pkey-subsystem.

But if none of the bits are set it will return 0 anyway right?

cheers