Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751544AbdINSZ7 (ORCPT ); Thu, 14 Sep 2017 14:25:59 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:39180 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751316AbdINSZ6 (ORCPT ); Thu, 14 Sep 2017 14:25:58 -0400 Date: Thu, 14 Sep 2017 19:25:56 +0100 From: Mark Rutland To: Tycho Andersen Cc: linux-kernel@vger.kernel.org, Marco Benatto , kernel-hardening@lists.openwall.com, linux-mm@kvack.org, Juerg Haefliger , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v6 07/11] arm64/mm, xpfo: temporarily map dcache regions Message-ID: <20170914182555.GB1711@remoulade> References: <20170907173609.22696-1-tycho@docker.com> <20170907173609.22696-8-tycho@docker.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170907173609.22696-8-tycho@docker.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1608 Lines: 49 On Thu, Sep 07, 2017 at 11:36:05AM -0600, Tycho Andersen wrote: > From: Juerg Haefliger > > If the page is unmapped by XPFO, a data cache flush results in a fatal > page fault, so let's temporarily map the region, flush the cache, and then > unmap it. > > v6: actually flush in the face of xpfo, and temporarily map the underlying > memory so it can be flushed correctly > > CC: linux-arm-kernel@lists.infradead.org > Signed-off-by: Juerg Haefliger > Signed-off-by: Tycho Andersen > --- > arch/arm64/mm/flush.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c > index 21a8d828cbf4..e335e3fd4fca 100644 > --- a/arch/arm64/mm/flush.c > +++ b/arch/arm64/mm/flush.c > @@ -20,6 +20,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -28,9 +29,15 @@ > void sync_icache_aliases(void *kaddr, unsigned long len) > { > unsigned long addr = (unsigned long)kaddr; > + unsigned long num_pages = XPFO_NUM_PAGES(addr, len); > + void *mapping[num_pages]; > > if (icache_is_aliasing()) { > + xpfo_temp_map(kaddr, len, mapping, > + sizeof(mapping[0]) * num_pages); > __clean_dcache_area_pou(kaddr, len); > + xpfo_temp_unmap(kaddr, len, mapping, > + sizeof(mapping[0]) * num_pages); Does this create the mapping in-place? Can we not just kmap_atomic() an alias? Or is there a problem with that? Thanks, Mark.