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SubjectRe: [PATCH v2] powerpc/mm: Add mask of always present MMU features
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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 <christophe.leroy@csgroup.eu>
> ---
> 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,
> +};
> +
> 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;
>
>

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