From 421fe93cc4b06b2f5e875cbe0f692800d4862ee5 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sun, 25 Oct 2009 10:23:04 +0000 Subject: ARM: ZERO_PAGE: Avoid flush_dcache_page() for zero page The zero page is read-only, and has its cache state cleared during boot. No further maintanence for this page is required. Signed-off-by: Russell King --- arch/arm/mm/fault-armv.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/arm/mm/fault-armv.c') diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index d0d17b6a3703..4fbc7de8b4ac 100644 --- a/arch/arm/mm/fault-armv.c +++ b/arch/arm/mm/fault-armv.c @@ -151,7 +151,14 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte) if (!pfn_valid(pfn)) return; + /* + * The zero page is never written to, so never has any dirty + * cache lines, and therefore never needs to be flushed. + */ page = pfn_to_page(pfn); + if (page == ZERO_PAGE(0)) + return; + mapping = page_mapping(page); #ifndef CONFIG_SMP if (test_and_clear_bit(PG_dcache_dirty, &page->flags)) -- cgit