From b8cd51afe05a98ef907e61c603d5c5b7ad6242d8 Mon Sep 17 00:00:00 2001 From: Steve Capper <steve.capper@linaro.org> Date: Thu, 9 Oct 2014 15:29:20 -0700 Subject: [PATCH] arm: mm: enable RCU fast_gup Activate the RCU fast_gup for ARM. We also need to force THP splits to broadcast an IPI s.t. we block in the fast_gup page walker. As THP splits are comparatively rare, this should not lead to a noticeable performance degradation. Some pre-requisite functions pud_write and pud_page are also added. Signed-off-by: Steve Capper <steve.capper@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Dann Frazier <dann.frazier@canonical.com> Cc: Hugh Dickins <hughd@google.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Will Deacon <will.deacon@arm.com> Cc: Christoffer Dall <christoffer.dall@linaro.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- arch/arm/Kconfig | 4 ++++ arch/arm/include/asm/pgtable-3level.h | 8 ++++++++ arch/arm/mm/flush.c | 15 +++++++++++++++ 3 files changed, 27 insertions(+) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index eafe6aea64ff..18f392f8b744 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1661,6 +1661,10 @@ config ARCH_SELECT_MEMORY_MODEL config HAVE_ARCH_PFN_VALID def_bool ARCH_HAS_HOLES_MEMORYMODEL || !SPARSEMEM +config HAVE_GENERIC_RCU_GUP + def_bool y + depends on ARM_LPAE + config HIGHMEM bool "High Memory Support" depends on MMU diff --git a/arch/arm/include/asm/pgtable-3level.h b/arch/arm/include/asm/pgtable-3level.h index 16122d4d7081..a31ecdad4b59 100644 --- a/arch/arm/include/asm/pgtable-3level.h +++ b/arch/arm/include/asm/pgtable-3level.h @@ -224,6 +224,8 @@ static inline pte_t pte_mkspecial(pte_t pte) #define __HAVE_ARCH_PMD_WRITE #define pmd_write(pmd) (pmd_isclear((pmd), L_PMD_SECT_RDONLY)) #define pmd_dirty(pmd) (pmd_isset((pmd), L_PMD_SECT_DIRTY)) +#define pud_page(pud) pmd_page(__pmd(pud_val(pud))) +#define pud_write(pud) pmd_write(__pmd(pud_val(pud))) #define pmd_hugewillfault(pmd) (!pmd_young(pmd) || !pmd_write(pmd)) #define pmd_thp_or_huge(pmd) (pmd_huge(pmd) || pmd_trans_huge(pmd)) @@ -231,6 +233,12 @@ static inline pte_t pte_mkspecial(pte_t pte) #ifdef CONFIG_TRANSPARENT_HUGEPAGE #define pmd_trans_huge(pmd) (pmd_val(pmd) && !pmd_table(pmd)) #define pmd_trans_splitting(pmd) (pmd_isset((pmd), L_PMD_SECT_SPLITTING)) + +#ifdef CONFIG_HAVE_RCU_TABLE_FREE +#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH +void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp); +#endif #endif #define PMD_BIT_FUNC(fn,op) \ diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index 43d54f5b26b9..265b836b3bd1 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -400,3 +400,18 @@ void __flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned l */ __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE); } + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#ifdef CONFIG_HAVE_RCU_TABLE_FREE +void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp) +{ + pmd_t pmd = pmd_mksplitting(*pmdp); + VM_BUG_ON(address & ~PMD_MASK); + set_pmd_at(vma->vm_mm, address, pmdp, pmd); + + /* dummy IPI to serialise against fast_gup */ + kick_all_cpus_sync(); +} +#endif /* CONFIG_HAVE_RCU_TABLE_FREE */ +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */