Re: [PATCH v2] powerpc/mm: Add mask of always present MMU features
From: Christophe Leroy <hidden>
Date: 2020-10-21 10:32:55
Also in:
linuxppc-dev
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 <redacted>
---
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
quoted hunk ↗ jump to hunk
--- 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;