From b5b6c9e9149d8a7c3f1d7b9d0c046c6184e1dd17 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Wed, 1 May 2013 12:23:05 +0100 Subject: [PATCH] arm64: Avoid cache flushing in flush_dcache_page() The flush_dcache_page() function is called when the kernel modified a page cache page. Since the D-cache on AArch64 does not have aliases this function can simply mark the page as dirty for later flushing via set_pte_at()/__sync_icache_dcache() if the page is executable (to ensure the I-D cache coherency). Signed-off-by: Catalin Marinas Reported-by: Will Deacon Acked-by: Will Deacon --- arch/arm64/mm/flush.c | 22 ++++------------------ 1 file changed, 4 insertions(+), 18 deletions(-) diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c index 88611c3a421a..b9cd7a4deeca 100644 --- a/arch/arm64/mm/flush.c +++ b/arch/arm64/mm/flush.c @@ -94,28 +94,14 @@ void __sync_icache_dcache(pte_t pte, unsigned long addr) } /* - * Ensure cache coherency between kernel mapping and userspace mapping of this - * page. + * This function is called when a page has been modified by the kernel. Mark + * it as dirty for later flushing when mapped in user space (if executable, + * see __sync_icache_dcache). */ void flush_dcache_page(struct page *page) { - struct address_space *mapping; - - /* - * The zero page is never written to, so never has any dirty cache - * lines, and therefore never needs to be flushed. - */ - if (page == ZERO_PAGE(0)) - return; - - mapping = page_mapping(page); - if (mapping && mapping_mapped(mapping)) { - __flush_dcache_page(page); - __flush_icache_all(); - set_bit(PG_dcache_clean, &page->flags); - } else { + if (test_bit(PG_dcache_clean, &page->flags)) clear_bit(PG_dcache_clean, &page->flags); - } } EXPORT_SYMBOL(flush_dcache_page); -- 2.20.1