From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Capper Subject: [PATCH V3 4/6] arm: mm: Enable RCU fast_gup Date: Thu, 28 Aug 2014 15:45:05 +0100 Message-ID: <1409237107-24228-5-git-send-email-steve.capper@linaro.org> References: <1409237107-24228-1-git-send-email-steve.capper@linaro.org> Return-path: Received: from mail-wg0-f45.google.com ([74.125.82.45]:35480 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751627AbaH1Opa (ORCPT ); Thu, 28 Aug 2014 10:45:30 -0400 Received: by mail-wg0-f45.google.com with SMTP id k14so850656wgh.4 for ; Thu, 28 Aug 2014 07:45:28 -0700 (PDT) In-Reply-To: <1409237107-24228-1-git-send-email-steve.capper@linaro.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, linux@arm.linux.org.uk, linux-arch@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org Cc: will.deacon@arm.com, gary.robertson@linaro.org, christoffer.dall@linaro.org, peterz@infradead.org, anders.roxell@linaro.org, dann.frazier@canonical.com, mark.rutland@arm.com, mgorman@suse.de, Steve Capper 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 Reviewed-by: Catalin Marinas --- 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 cc740d2..0e5b47f 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1645,6 +1645,10 @@ 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 16122d4..a31ecdad 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 43d54f5..265b836 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 */ -- 1.9.3