From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steve Capper Subject: [RFC PATCH V4 7/7] arm64: mm: Enable RCU fast_gup Date: Fri, 28 Mar 2014 15:01:32 +0000 Message-ID: <1396018892-6773-8-git-send-email-steve.capper@linaro.org> References: <1396018892-6773-1-git-send-email-steve.capper@linaro.org> Return-path: Received: from mail-we0-f175.google.com ([74.125.82.175]:55235 "EHLO mail-we0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751839AbaC1PCA (ORCPT ); Fri, 28 Mar 2014 11:02:00 -0400 Received: by mail-we0-f175.google.com with SMTP id q58so2696380wes.20 for ; Fri, 28 Mar 2014 08:01:58 -0700 (PDT) In-Reply-To: <1396018892-6773-1-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-mm@kvack.org, linux-arch@vger.kernel.org Cc: peterz@infradead.org, gary.robertson@linaro.org, anders.roxell@linaro.org, akpm@linux-foundation.org, Steve Capper Activate the RCU fast_gup for ARM64. 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. Signed-off-by: Steve Capper --- arch/arm64/Kconfig | 3 +++ arch/arm64/include/asm/pgtable.h | 4 ++++ arch/arm64/mm/flush.c | 19 +++++++++++++++++++ 3 files changed, 26 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6185f95..9f5a81a 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -86,6 +86,9 @@ config GENERIC_CSUM config GENERIC_CALIBRATE_DELAY def_bool y +config HAVE_RCU_GUP + def_bool y + config ZONE_DMA32 def_bool y diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index aa3917c..0e148ae 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -245,6 +245,10 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, #ifdef CONFIG_TRANSPARENT_HUGEPAGE #define pmd_trans_huge(pmd) (pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT)) #define pmd_trans_splitting(pmd) (pmd_val(pmd) & PMD_SECT_SPLITTING) +#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH +struct vm_area_struct; +void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp); #endif #define PMD_BIT_FUNC(fn,op) \ diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c index e4193e3..ddf96c1 100644 --- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -103,3 +103,22 @@ EXPORT_SYMBOL(flush_dcache_page); */ EXPORT_SYMBOL(flush_cache_all); EXPORT_SYMBOL(flush_icache_range); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#ifdef CONFIG_HAVE_RCU_TABLE_FREE +static void thp_splitting_flush_sync(void *arg) +{ +} + +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 */ + smp_call_function(thp_splitting_flush_sync, NULL, 1); +} +#endif /* CONFIG_HAVE_RCU_TABLE_FREE */ +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ -- 1.8.1.4