From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 3BECA8E001A for ; Wed, 23 Jan 2019 09:56:58 -0500 (EST) Received: by mail-pf1-f199.google.com with SMTP id q63so1780555pfi.19 for ; Wed, 23 Jan 2019 06:56:58 -0800 (PST) Received: from userp2120.oracle.com (userp2120.oracle.com. [156.151.31.85]) by mx.google.com with ESMTPS id q20si19089535pgl.268.2019.01.23.06.56.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 Jan 2019 06:56:57 -0800 (PST) Date: Wed, 23 Jan 2019 09:56:03 -0500 From: Konrad Rzeszutek Wilk Subject: Re: [RFC PATCH v7 07/16] arm64/mm, xpfo: temporarily map dcache regions Message-ID: <20190123145551.GD19289@Konrads-MacBook-Pro.local> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Khalid Aziz Cc: juergh@gmail.com, tycho@tycho.ws, jsteckli@amazon.de, ak@linux.intel.com, torvalds@linux-foundation.org, liran.alon@oracle.com, keescook@google.com, Juerg Haefliger , deepa.srinivasan@oracle.com, chris.hyser@oracle.com, tyhicks@canonical.com, dwmw@amazon.co.uk, andrew.cooper3@citrix.com, jcm@redhat.com, boris.ostrovsky@oracle.com, kanth.ghatraju@oracle.com, joao.m.martins@oracle.com, jmattson@google.com, pradeep.vincent@oracle.com, john.haxby@oracle.com, tglx@linutronix.de, kirill.shutemov@linux.intel.com, hch@lst.de, steven.sistare@oracle.com, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Tycho Andersen On Thu, Jan 10, 2019 at 02:09:39PM -0700, Khalid Aziz 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 > Signed-off-by: Khalid Aziz > --- > 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 30695a868107..f12f26b60319 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); Is it possible that the 'len' is more than 32 pages? Or say 1000's of pages? Which would blow away your stack. > + 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); > __flush_icache_all(); > } else { > flush_icache_range(addr, addr + len); > -- > 2.17.1 >