From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S932415AbdESURn (ORCPT <rfc822;w@1wt.eu>);
        Fri, 19 May 2017 16:17:43 -0400
Received: from mx1.redhat.com ([209.132.183.28]:39600 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1756237AbdESURj (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 19 May 2017 16:17:39 -0400
DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 6164980C00
Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com
Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jpoimboe@redhat.com
DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 6164980C00
Date: Fri, 19 May 2017 15:16:51 -0500
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>, linux-arch@vger.kernel.org,
        linux-efi@vger.kernel.org, kvm@vger.kernel.org,
        linux-doc@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org,
        linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
        linux-mm@kvack.org, iommu@lists.linux-foundation.org,
        Rik van Riel <riel@redhat.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Toshimitsu Kani <toshi.kani@hpe.com>, Arnd Bergmann <arnd@arndb.de>,
        Jonathan Corbet <corbet@lwn.net>,
        Matt Fleming <matt@codeblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@redhat.com>, Joerg Roedel <joro@8bytes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Larry Woodman <lwoodman@redhat.com>,
        Brijesh Singh <brijesh.singh@amd.com>, Ingo Molnar <mingo@redhat.com>,
        Andy Lutomirski <luto@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dave Young <dyoung@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH v5 32/32] x86/mm: Add support to make use of Secure
 Memory Encryption
Message-ID: <20170519201651.dhayf2pwjlsnouz4@treble>
References: <20170418211612.10190.82788.stgit@tlendack-t1.amdoffice.net>
 <20170418212223.10190.85121.stgit@tlendack-t1.amdoffice.net>
 <c29edaff-24f2-ee9b-4142-bdbf8c42083f@amd.com>
 <20170519113005.3f5kwzg4pgh7j6a5@pd.tnic>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20170519113005.3f5kwzg4pgh7j6a5@pd.tnic>
User-Agent: Mutt/1.6.0.1 (2016-04-01)
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 19 May 2017 20:17:17 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, May 19, 2017 at 01:30:05PM +0200, Borislav Petkov wrote:
> > it is called so early. I can get past it by adding:
> > 
> > CFLAGS_mem_encrypt.o := $(nostackp)
> > 
> > in the arch/x86/mm/Makefile, but that obviously eliminates the support
> > for the whole file.  Would it be better to split out the sme_enable()
> > and other boot routines into a separate file or just apply the
> > $(nostackp) to the whole file?
> 
> Josh might have a better idea here... CCed.

I'm the stack validation guy, not the stack protection guy :-)

But there is a way to disable compiler options on a per-function basis
with the gcc __optimize__ function attribute.  For example:

  __attribute__((__optimize__("no-stack-protector")))

-- 
Josh