From patchwork Mon Jun 1 08:22:03 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herbert Xu X-Patchwork-Id: 6519361 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: X-Original-To: patchwork-linux-crypto@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 739609F326 for ; Mon, 1 Jun 2015 08:22:21 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 99C192049E for ; Mon, 1 Jun 2015 08:22:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DDB1205DA for ; Mon, 1 Jun 2015 08:22:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752683AbbFAIWN (ORCPT ); Mon, 1 Jun 2015 04:22:13 -0400 Received: from helcar.hengli.com.au ([209.40.204.226]:39136 "EHLO helcar.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750820AbbFAIWK (ORCPT ); Mon, 1 Jun 2015 04:22:10 -0400 Received: from gondolin.me.apana.org.au ([192.168.0.6]) by norbury.hengli.com.au with esmtp (Exim 4.80 #3 (Debian)) id 1YzKyz-0000Y1-RB; Mon, 01 Jun 2015 18:22:05 +1000 Received: from herbert by gondolin.me.apana.org.au with local (Exim 4.80) (envelope-from ) id 1YzKyx-00037H-Uh; Mon, 01 Jun 2015 16:22:03 +0800 Date: Mon, 1 Jun 2015 16:22:03 +0800 From: Herbert Xu To: "David S. Miller" , Linux Crypto Mailing List Subject: crypto: scatterwalk - Hide PageSlab call to optimise away flush_dcache_page Message-ID: <20150601082203.GA11946@gondor.apana.org.au> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On architectures where flush_dcache_page is not needed, we will end up generating all the code up to the PageSlab call. This is because PageSlab operates on a volatile pointer and thus cannot be optimised away. This patch works around this by checking whether flush_dcache_page is needed before we call PageSlab which then allows PageSlab to be compiled awy. Signed-off-by: Herbert Xu diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c index 2ef9cbb..ea5815c 100644 --- a/crypto/scatterwalk.c +++ b/crypto/scatterwalk.c @@ -54,7 +54,11 @@ static void scatterwalk_pagedone(struct scatter_walk *walk, int out, struct page *page; page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); - if (!PageSlab(page)) + /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as + * PageSlab cannot be optimised away per se due to + * use of volatile pointer. + */ + if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page)) flush_dcache_page(page); }