From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752391Ab3JWNqm (ORCPT ); Wed, 23 Oct 2013 09:46:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6815 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751316Ab3JWNqk (ORCPT ); Wed, 23 Oct 2013 09:46:40 -0400 Message-ID: <1382535972.1768.68.camel@deneb.redhat.com> Subject: Re: [PATCH] arm64: allow ioremap_cache() to use existing RAM mappings From: Mark Salter To: Catalin Marinas Cc: Will Deacon , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Date: Wed, 23 Oct 2013 09:46:12 -0400 In-Reply-To: <1382519898.10408.1.camel@mbp> References: <1382362594-24947-1-git-send-email-msalter@redhat.com> <1382519898.10408.1.camel@mbp> Organization: Red Hat, Inc Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2013-10-23 at 10:18 +0100, Catalin Marinas wrote: > On Mon, 2013-10-21 at 14:36 +0100, msalter@redhat.com wrote: > > diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c > > index 1725cd6..fb44b3d 100644 > > --- a/arch/arm64/mm/ioremap.c > > +++ b/arch/arm64/mm/ioremap.c > > @@ -79,6 +79,21 @@ void __iounmap(volatile void __iomem *io_addr) > > { > > void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr); > > > > + /* Nothing to do for normal memory. See ioremap_cache() */ > > + if (pfn_valid(__virt_to_phys(addr) >> PAGE_SHIFT)) > > + return; > > addr here can be some I/O address mapped previously, so __virt_to_phys() > is not valid (you don't actually get the pfn by shifting). > Yeah, that's ugly. The thought was that only the kernel mapping of RAM would yield a valid address from __virt_to_phys(). Anything else, like a mapping of I/O space would lead to an invalid PFN. There's probably a clearer way of doing that that. Other than that, is the general concept of the patch reasonable? --Mark