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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 2D065ECDFAA for ; Thu, 12 Jul 2018 23:02:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A8962208E3 for ; Thu, 12 Jul 2018 23:02:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="Rj+iutiQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A8962208E3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387610AbeGLXOA (ORCPT ); Thu, 12 Jul 2018 19:14:00 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:34948 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387438AbeGLXN7 (ORCPT ); Thu, 12 Jul 2018 19:13:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2014; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=b2uKsV2SbcwTl9BlsRYe2TqSDPoQrqq7OdIuw8Qkzm4=; b=Rj+iutiQSneie/wpMTi0z+xcG L5uNWfoLt8GVrKa1ZdoYvZ5NK+uOdRTT8us9ahqg8pFEfRFtgj6G6cRyu2zTH0zVWtO9TvMrtvCpT aSPEUk4qXTwCulcmeUq695MknQ4g9aFIGtGpg5Y4BVcVSu26IeJ3ghuI0OYicBqI73OW8=; Received: from n2100.armlinux.org.uk ([2002:4e20:1eda:1:214:fdff:fe10:4f86]:39558) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.90_1) (envelope-from ) id 1fdkb5-0000kD-PR; Fri, 13 Jul 2018 00:02:04 +0100 Received: from linux by n2100.armlinux.org.uk with local (Exim 4.90_1) (envelope-from ) id 1fdkb0-0008SM-BL; Fri, 13 Jul 2018 00:01:58 +0100 Date: Fri, 13 Jul 2018 00:01:57 +0100 From: Russell King - ARM Linux To: Kees Cook Cc: Thierry Reding , Nicolas Pitre , Stephen Warren , Arnd Bergmann , Ard Biesheuvel , Marc Zyngier , Stephen Warren , Stefan Agner , LKML , Matthias Kaehlcke , Dmitry Osipenko , Robin Murphy , linux-arm-kernel , Bero =?iso-8859-1?Q?Rosenkr=E4nzer?= Subject: Re: [PATCH v2 3/6] ARM: trusted_foundations: do not use naked function Message-ID: <20180712230156.GY17271@n2100.armlinux.org.uk> References: <20180325180959.28008-1-stefan@agner.ch> <20180325180959.28008-4-stefan@agner.ch> <704c863a-0b5a-6396-d7da-f0ed17b7cca2@gmail.com> <263337af-7541-be9e-3db6-6cb987fd08fb@arm.com> <498de826-6e6c-63d8-00d6-f394b2725a34@wwwdotorg.org> <507a66ab9ab530a6d71db7a74f11ddfb@agner.ch> <20180417081109.GA5804@ulmo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Thu, Jul 12, 2018 at 03:43:10PM -0700, Kees Cook wrote: > On Tue, Apr 17, 2018 at 1:11 AM, Thierry Reding wrote: > > On Mon, Apr 16, 2018 at 08:21:09PM +0200, Stefan Agner wrote: > >> On 16.04.2018 18:08, Stephen Warren wrote: > >> > On 04/16/2018 09:56 AM, Stefan Agner wrote: > >> >> On 27.03.2018 14:16, Dmitry Osipenko wrote: > >> >>> On 27.03.2018 14:54, Robin Murphy wrote: > >> >>>> On 26/03/18 22:20, Dmitry Osipenko wrote: > >> >>>>> On 25.03.2018 21:09, Stefan Agner wrote: > >> >>>>>> As documented in GCC naked functions should only use Basic asm > >> >>>>>> syntax. The Extended asm or mixture of Basic asm and "C" code is > >> >>>>>> not guaranteed. Currently this works because it was hard coded > >> >>>>>> to follow and check GCC behavior for arguments and register > >> >>>>>> placement. > >> >>>>>> > >> >>>>>> Furthermore with clang using parameters in Extended asm in a > >> >>>>>> naked function is not supported: > >> >>>>>> arch/arm/firmware/trusted_foundations.c:47:10: error: parameter > >> >>>>>> references not allowed in naked functions > >> >>>>>> : "r" (type), "r" (arg1), "r" (arg2) > >> >>>>>> ^ > >> >>>>>> > >> >>>>>> Use a regular function to be more portable. This aligns also with > >> >>>>>> the other smc call implementations e.g. in qcom_scm-32.c and > >> >>>>>> bcm_kona_smc.c. > >> >>>>>> > >> >>>>>> Cc: Dmitry Osipenko > >> >>>>>> Cc: Stephen Warren > >> >>>>>> Cc: Thierry Reding > >> >>>>>> Signed-off-by: Stefan Agner > >> >>>>>> --- > >> >>>>>> Changes in v2: > >> >>>>>> - Keep stmfd/ldmfd to avoid potential ABI issues > >> >>>>>> > >> >>>>>> arch/arm/firmware/trusted_foundations.c | 14 +++++++++----- > >> >>>>>> 1 file changed, 9 insertions(+), 5 deletions(-) > >> >>>>>> > >> >>>>>> diff --git a/arch/arm/firmware/trusted_foundations.c > >> >>>>>> b/arch/arm/firmware/trusted_foundations.c > >> >>>>>> index 3fb1b5a1dce9..689e6565abfc 100644 > >> >>>>>> --- a/arch/arm/firmware/trusted_foundations.c > >> >>>>>> +++ b/arch/arm/firmware/trusted_foundations.c > >> >>>>>> @@ -31,21 +31,25 @@ > >> >>>>>> static unsigned long cpu_boot_addr; > >> >>>>>> -static void __naked tf_generic_smc(u32 type, u32 arg1, u32 arg2) > >> >>>>>> +static void tf_generic_smc(u32 type, u32 arg1, u32 arg2) > >> >>>>>> { > >> >>>>>> + register u32 r0 asm("r0") = type; > >> >>>>>> + register u32 r1 asm("r1") = arg1; > >> >>>>>> + register u32 r2 asm("r2") = arg2; > >> >>>>>> + > >> >>>>>> asm volatile( > >> >>>>>> ".arch_extension sec\n\t" > >> >>>>>> - "stmfd sp!, {r4 - r11, lr}\n\t" > >> >>>>>> + "stmfd sp!, {r4 - r11}\n\t" > >> >>>>>> __asmeq("%0", "r0") > >> >>>>>> __asmeq("%1", "r1") > >> >>>>>> __asmeq("%2", "r2") > >> >>>>>> "mov r3, #0\n\t" > >> >>>>>> "mov r4, #0\n\t" > >> >>>>>> "smc #0\n\t" > >> >>>>>> - "ldmfd sp!, {r4 - r11, pc}" > >> >>>>>> + "ldmfd sp!, {r4 - r11}\n\t" > >> >>>>>> : > >> >>>>>> - : "r" (type), "r" (arg1), "r" (arg2) > >> >>>>>> - : "memory"); > >> >>>>>> + : "r" (r0), "r" (r1), "r" (r2) > >> >>>>>> + : "memory", "r3", "r12", "lr"); > >> >>>>> > >> >>>>> Although seems "lr" won't be affected by SMC invocation because it should be > >> >>>>> banked and hence could be omitted entirely from the code. Maybe somebody could > >> >>>>> confirm this. > >> >>>> Strictly per the letter of the architecture, the SMC could be trapped to Hyp > >> >>>> mode, and a hypervisor might clobber LR_usr in the process of forwarding the > >> >>>> call to the firmware secure monitor (since Hyp doesn't have a banked LR of its > >> >>>> own). Admittedly there are probably no real systems with the appropriate > >> >>>> hardware/software combination to hit that, but on the other hand if this gets > >> >>>> inlined where the compiler has already created a stack frame then an LR clobber > >> >>>> is essentially free, so I reckon we're better off keeping it for reassurance. > >> >>>> This isn't exactly a critical fast path anyway. > >> >>> > >> >>> Okay, thank you for the clarification. > >> >> > >> >> So it seems this change is fine? > >> >> > >> >> Stephen, you picked up changes for this driver before, is this patch > >> >> going through your tree? > >> > > >> > You had best ask Thierry; he's taken over Tegra maintenance upstream. > >> > But that said, don't files in arch/arm go through Russell? > >> > >> I think the last patches applied to that file went through your tree. > >> > >> Thierry, Russel, any preferences? > > > > I don't mind picking this up into the Tegra tree. Might be a good idea > > to move this into drivers/firmware, though, since that's where all the > > other firmware-related drivers reside. > > > > Firmware code, such as the BPMP driver, usually goes through ARM-SoC > > these days. I think this is in the same category. > > > > Russell, any objections to me picking this patch up and moving it into > > drivers/firmware? > > Please take this -- without it I'm seeing build failures on the arm > allmodconfig under gcc 7.3.0: Sorry, I'd completely missed this... now replied on the original patch. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 13.8Mbps down 630kbps up According to speedtest.net: 13Mbps down 490kbps up