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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 EE7DDC2D0EF for ; Fri, 17 Apr 2020 14:13:51 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BDDCF2076A for ; Fri, 17 Apr 2020 14:13:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RRgUpIny"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="vXuRLTov" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BDDCF2076A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=j8NwlYe4yWdHEmbcAU1ZPNFSq3fGj4xsGVcX5QBGbl8=; b=RRgUpInyVqmjbM F8S2G/SsDsIzVcpQsEXAvrmq/8uedSFWfQijWsxgC3z3NdLP2ytBgXipyMxBdn7XGB4O+irKaxXCG ejJMI9X4N3tqooNJ0khrtEzjhVt8iB0LMNkOrSFP/YGvlI1ZNmr7+NW5SBRkczM1yGixavqHDT83X Qk+Pr9fXmkutRcltRIZWAvdbbkW9Cwm3AiRdy8F+8dKFiej7Z6AJchYfVnAIUiQaZh3Ze0/mc/yhX Q+Yv/koArPzougJ1GblWDZec2kuXC1YiTj8sjro6EqgEEkii1d/gE9xSB2yGf8WXBnB8mxf6u6YWW YnVv4ipbV/GuyXSQss5A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jPRkc-0004BB-7Y; Fri, 17 Apr 2020 14:13:50 +0000 Received: from conssluserg-04.nifty.com ([210.131.2.83]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jPRkY-0004A3-DI for linux-arm-kernel@lists.infradead.org; Fri, 17 Apr 2020 14:13:48 +0000 Received: from mail-ua1-f45.google.com (mail-ua1-f45.google.com [209.85.222.45]) (authenticated) by conssluserg-04.nifty.com with ESMTP id 03HEDDdc011310 for ; Fri, 17 Apr 2020 23:13:13 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-04.nifty.com 03HEDDdc011310 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1587132794; bh=soczHQygZ5e4Z4/uBgr0PVGiMli0DNK+wn9N64tR5qU=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=vXuRLTovDrQmMb0Jz37P9s2LBa6Jb1e/OUiRedx63I0IFnBEDdaseDJmrt8I6+yNf YwxQQopMU2clgNfcN5XYa5Pdao15glEfClHbc9nH43HSs1Julc8SjX09ZfxxNGgNZ1 L2y3yIwwSDwMFX+ug9VhWRfr7yo4w7BJoeadMqw4WrhuM6BzVqXadkqpeahMtW4mME iRKHSf/7aXQtWqNWcjEqbNd1y2k7an7fr66xZ6JGbirh4am9JHd6+siWU3PaImO0sO Eg2kf5oJczJgxOoSYG0X5oXG3RdLGssN/7QKmvFhvYf2WvL7C7tM5MDUBnGKcAH8mv pI488dLZ0hQJw== X-Nifty-SrcIP: [209.85.222.45] Received: by mail-ua1-f45.google.com with SMTP id s5so693450uad.4 for ; Fri, 17 Apr 2020 07:13:13 -0700 (PDT) X-Gm-Message-State: AGi0PubNomNfGmD0f6OyGyJpcOgsmNxT2qOsM+7YpQgIRXRO2dQ6EMup xUgEmG8+XmMou/wB5ELkvLuK7WmZF7teK5GnZWE= X-Google-Smtp-Source: APiQypKhiuo80RsLEisith0XyQOFUV3PzTzMi+mrapjPQLCKwWkCyn51WYWMMdjYPdS/P6p4Vjn2U9i/In6A9eNfdOo= X-Received: by 2002:ab0:20d6:: with SMTP id z22mr2640996ual.121.1587132792213; Fri, 17 Apr 2020 07:13:12 -0700 (PDT) MIME-Version: 1.0 References: <20200409232728.231527-1-caij2003@gmail.com> <20200410123301.GX25745@shell.armlinux.org.uk> <202004141258.6D9CB92507@keescook> <202004150833.E2E9A89E0@keescook> In-Reply-To: <202004150833.E2E9A89E0@keescook> From: Masahiro Yamada Date: Fri, 17 Apr 2020 23:12:35 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] ARM: do not assemble iwmmxt.S with LLVM toolchain To: Kees Cook X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200417_071346_784242_F21F7381 X-CRM114-Status: GOOD ( 21.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linus Walleij , Peter Smith , Stefan Agner , David Howells , Mauro Carvalho Chehab , Manoj Gupta , Benjamin Gaignard , "Joel Fernandes \(Google\)" , Kristof Beyls , Jian Cai , Bartosz Golaszewski , Ilie Halip , Russell King - ARM Linux admin , Krzysztof Kozlowski , Ard Biesheuvel , clang-built-linux , Sami Tolvanen , Luis Lozano , Masami Hiramatsu , Arnd Bergmann , "Steven Rostedt \(VMware\)" , Jian Cai , Stephen Hines , Doug Anderson , Dan Williams , Linux ARM , Greg Kroah-Hartman , Nick Desaulniers , "linux-kernel@vger.kernel.org" , Patrick Bellasi , "Eric W. Biederman" , Tejun Heo , Andrew Morton Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi On Thu, Apr 16, 2020 at 12:44 AM Kees Cook wrote: > > On Wed, Apr 15, 2020 at 12:32:17PM +0200, Ard Biesheuvel wrote: > > To reiterate my point: I strongly prefer minor asm surgery over > > elaborate Kconfig plumbing if it means we can retain the functionality > > even when using LLVM tools. In particular, the use of macros to > > implement missing ISA support should be considered before any other > > solution, as these are already being used widely across architectures > > to fill in such gaps. > > Yeah, this seems like the right place to start from. It sounded like > there were cases where the people with knowledge needed to accomplish > the macro creation were not always immediately available. But, yes, > let's get iwmmxt fixed up. > > > This code has been around since 2004. It has never been possible to > > assemble it with Clang's assembler. So the only thing this patch gives > > you is the ability to switch from a .config where IWMMXT was disabled > > by hand to one where it gets disabled automatically by Kconfig. > > Right -- I meant "let's fix iwmmxt with macro magic" not "let's disable > it". I did want to point out the Kconfig disabling may be needed in > other cases. > > > So what hard-won ground are we losing here? Did IWMMXT recently get > > enabled in a defconfig that you care about? > > It's a CI's ability to do randconfig builds to catch new stuff. (i.e. > where "disabled by hand" isn't part of the process.) Since there are > multiple CIs doing multi-architecture builds we need to get these things > fixed upstream, not a CI's local patch stacks or Kconfig whitelists, > etc. And when the expertise isn't available to fix arch-specific stuff, > Kconfig negative depends seems like a reasonable middle ground. I, too, > prefer fixes that allow Clang to do its work without wrecking things > for GNU as. > > > I am not disagreeing with you here, and I have worked with Nick, > > Nathan and Stefan on numerous occasions to get Clang related build > > issues solved. > > Yup! Totally; this thread just looked very familiar to me from doing > treewide stuff and I didn't want what I thought looked like the core > points to get lost in the details. :) > > -- > Kees Cook When I started to read this thread, I just slightly preferred depends on $(as-instr, ) over depends on AS_IS_CLANG because it is what we recently did for x86. commit 5e8ebd841a44b895e2bab5e874ff7d333ca31135 But, Ard's macro approach seems even better. I do not know how difficult to replace the arch/x86/Kconfig.assembler with .macro Anyway, arch/x86/Kconfig.assembler will be gone when we raise the binutils version next time. -- Best Regards Masahiro Yamada _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel