Messages in this thread | | | Subject | Re: [PATCH v2] powerpc/mm: Add mask of always present MMU features | From | Christophe Leroy <> | Date | Wed, 21 Oct 2020 18:37:41 +0200 |
| |
Le 21/10/2020 à 16:25, Aneesh Kumar K.V a écrit : > Christophe Leroy <christophe.leroy@csgroup.eu> 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 <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, >>> +}; > > 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
Yes you are right, it will be simpler, and consistant with CPU_FTR_ALWAYS which is partly set with defines after all.
Christophe
> > > >>> + >>> 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; >>> >>>
| |