From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E17EFC433E1 for ; Wed, 27 May 2020 13:34:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C11F6207CB for ; Wed, 27 May 2020 13:34:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388342AbgE0NeK (ORCPT ); Wed, 27 May 2020 09:34:10 -0400 Received: from elvis.franken.de ([193.175.24.41]:41218 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387901AbgE0NeK (ORCPT ); Wed, 27 May 2020 09:34:10 -0400 Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1jdwC8-0001yv-00; Wed, 27 May 2020 15:34:08 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 88D52C059B; Wed, 27 May 2020 15:33:56 +0200 (CEST) Date: Wed, 27 May 2020 15:33:56 +0200 From: Thomas Bogendoerfer To: Jiaxun Yang Cc: linux-mips@vger.kernel.org, Kees Cook , Borislav Petkov , Heiko Carstens , Fangrui Song , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/3] MIPS: Move kernel head into a standalone section Message-ID: <20200527133356.GA16622@alpha.franken.de> References: <20200527063438.391949-1-jiaxun.yang@flygoat.com> <20200527063438.391949-3-jiaxun.yang@flygoat.com> <20200527115354.GC13965@alpha.franken.de> <20200527200522.23c4e86f@halation.net.flygoat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200527200522.23c4e86f@halation.net.flygoat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 27, 2020 at 08:05:22PM +0800, Jiaxun Yang wrote: > On Wed, 27 May 2020 13:53:54 +0200 > Thomas Bogendoerfer wrote: > > > On Wed, May 27, 2020 at 02:34:33PM +0800, Jiaxun Yang wrote: > > > That's what already done by Arm64 and other architectures. > > > That would allow us put more things like PE headers safely into > > > the header. > > > > > > Signed-off-by: Jiaxun Yang > > > --- > > > arch/mips/kernel/head.S | 4 ++-- > > > arch/mips/kernel/vmlinux.lds.S | 8 ++++++-- > > > 2 files changed, 8 insertions(+), 4 deletions(-) > > > > > > diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S > > > index c7c2795837e7..8081a905a71c 100644 > > > --- a/arch/mips/kernel/head.S > > > +++ b/arch/mips/kernel/head.S > > > @@ -59,6 +59,8 @@ > > > #endif > > > .endm > > > > > > + __HEAD > > > +_head: > > > #ifndef CONFIG_NO_EXCEPT_FILL > > > /* > > > * Reserved space for exception handlers. > > > > I'm adding the missing piece, why this change ist broken: > > > > * Necessary for machines which link their kernels at KSEG0. > > > > by putting something in front of that will probably break platforms > > making use of "feature". If we can make sure, we don't need it > > anymore, we should first remove this and then add __HEAD part. > > __HEAD is just marking the section of code. > It will not add anything to the binary. oops, should have looked it up first. You mentioned PE headers and I thought it will be added this way. > Btw: I just noticed this patch may break relocatable kernel. I'll delay > it for next merge window. ok. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]