Christophe Leroy <[email protected]> writes:
> Le 12/10/2020 à 17:39, Christophe Leroy a écrit :
>> On the same principle as commit 773edeadf672 ("powerpc/mm: Add mask
>> of possible MMU features"), add mask for MMU features that are
>> always there in order to optimise out dead branches.
>>
>> Signed-off-by: Christophe Leroy <[email protected]>
>> ---
>> v2: Features must be anded with MMU_FTRS_POSSIBLE instead of ~0, otherwise
>> MMU_FTRS_ALWAYS is ~0 when no #ifdef matches.
>
> This is still not enough. For BOOK3S/32, MMU_FTRS_POSSIBLE is still too much.
> We need a #ifdef CONFIG_PPC_BOOK3S_32 with 0.
>
> Christophe
>
>> ---
>> arch/powerpc/include/asm/mmu.h | 25 +++++++++++++++++++++++++
>> 1 file changed, 25 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
>> index 255a1837e9f7..64e7e7f7cda9 100644
>> --- a/arch/powerpc/include/asm/mmu.h
>> +++ b/arch/powerpc/include/asm/mmu.h
>> @@ -201,8 +201,30 @@ enum {
>> 0,
>> };
>>
>> +enum {
>> + MMU_FTRS_ALWAYS =
>> +#ifdef CONFIG_PPC_8xx
>> + MMU_FTR_TYPE_8xx &
>> +#endif
>> +#ifdef CONFIG_40x
>> + MMU_FTR_TYPE_40x &
>> +#endif
>> +#ifdef CONFIG_PPC_47x
>> + MMU_FTR_TYPE_47x &
>> +#elif defined(CONFIG_44x)
>> + MMU_FTR_TYPE_44x &
>> +#endif
>> +#if defined(CONFIG_E200) || defined(CONFIG_E500)
>> + MMU_FTR_TYPE_FSL_E &
>> +#endif
>> + MMU_FTRS_POSSIBLE,
>> +};
Will it be simpler if we make it a #define like below?
#ifdef CONFIG_PPC_8XX
#define MMU_FTR_ALWAYS MMU_FTR_TYPE_8XX & MMU_FTR_POSSIBLE
#endif
>> +
>> static inline bool early_mmu_has_feature(unsigned long feature)
>> {
>> + if (MMU_FTRS_ALWAYS & feature)
>> + return true;
>> +
>> return !!(MMU_FTRS_POSSIBLE & cur_cpu_spec->mmu_features & feature);
>> }
>>
>> @@ -231,6 +253,9 @@ static __always_inline bool mmu_has_feature(unsigned
>> long feature)
>> }
>> #endif
>>
>> + if (MMU_FTRS_ALWAYS & feature)
>> + return true;
>> +
>> if (!(MMU_FTRS_POSSIBLE & feature))
>> return false;
>>
>>
