From mboxrd@z Thu Jan 1 00:00:00 1970 From: gmbnomis@gmail.com (Simon Baatz) Date: Mon, 28 May 2012 01:11:58 +0200 Subject: [RFC/PATCH 1/1] ARM: Handle user space mapped pages in flush_kernel_dcache_page In-Reply-To: <1338160318-20712-1-git-send-email-gmbnomis@gmail.com> References: <1338160318-20712-1-git-send-email-gmbnomis@gmail.com> Message-ID: <1338160318-20712-2-git-send-email-gmbnomis@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Commit f8b63c1 made flush_kernel_dcache_page a no-op assuming that the pages it needs to handle are kernel mapped only. However, for example when doing direct I/O, pages with user space mappings may occur. Thus, continue to do lazy flushing if there are no user space mappings. Otherwise, flush the kernel cache lines directly. Signed-off-by: Simon Baatz --- arch/arm/include/asm/cacheflush.h | 4 ++++ arch/arm/mm/flush.c | 22 ++++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index d5d8d5c..c6c81d5 100644 --- a/arch/arm/include/asm/cacheflush.h +++ b/arch/arm/include/asm/cacheflush.h @@ -303,6 +303,10 @@ static inline void flush_anon_page(struct vm_area_struct *vma, #define ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE static inline void flush_kernel_dcache_page(struct page *page) { + extern void __flush_kernel_dcache_page(struct page *); + /* highmem pages are always flushed upon kunmap already */ + if ((cache_is_vivt() || cache_is_vipt_aliasing()) && !PageHighMem(page)) + __flush_kernel_dcache_page(page); } #define flush_dcache_mmap_lock(mapping) \ diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c index 7745854..bcba3a9 100644 --- a/arch/arm/mm/flush.c +++ b/arch/arm/mm/flush.c @@ -192,6 +192,28 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page) page->index << PAGE_CACHE_SHIFT); } +/* + * Ensure cache coherency for kernel mapping of this page. + * + * If the page only exists in the page cache and there are no user + * space mappings, this is a no-op since the page was already marked + * dirty@creation. Otherwise, we need to flush the dirty kernel + * cache lines directly. + * + * We can assume that the page is no high mem page, see + * flush_kernel_dcache_page. + */ +void __flush_kernel_dcache_page(struct page *page) +{ + struct address_space *mapping; + + mapping = page_mapping(page); + + if (!mapping || mapping_mapped(mapping)) + __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE); +} +EXPORT_SYMBOL(__flush_kernel_dcache_page); + static void __flush_dcache_aliases(struct address_space *mapping, struct page *page) { struct mm_struct *mm = current->active_mm; -- 1.7.9.5