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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 9FB67C5517A for ; Tue, 10 Nov 2020 07:45:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4264E2080A for ; Tue, 10 Nov 2020 07:45:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="rHy97eW3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729527AbgKJHpo (ORCPT ); Tue, 10 Nov 2020 02:45:44 -0500 Received: from mail.kernel.org ([198.145.29.99]:48644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728478AbgKJHpn (ORCPT ); Tue, 10 Nov 2020 02:45:43 -0500 Received: from mail-oi1-f181.google.com (mail-oi1-f181.google.com [209.85.167.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B8B3B2080A for ; Tue, 10 Nov 2020 07:45:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604994342; bh=V5seme1Dc/72WBLamjIKlKO0QKIx50V3ebIunpvCVQU=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=rHy97eW38Z307C23x5Y7jUZmd52+ejdw/IUkAraq+5VjwJXxzMMnAw7e3l/ghaH2C IVMBWRp04J2zPQfbXfJPj7akqwoO6n0ZkXWjjD7Yk7ZjHB9+Sge/79N9ZIUWxzsGx3 fiNKzwkA2BVQUdCRlPdBEBtIsU7J/fWHrVN+1SiY= Received: by mail-oi1-f181.google.com with SMTP id w188so7767451oib.1 for ; Mon, 09 Nov 2020 23:45:42 -0800 (PST) X-Gm-Message-State: AOAM530pAQ3NFusKHt0IxJw/5K6owI5yDxPS31WdNPRgqNxTk7DI0lM1 T5hBtZyOfGeH65RXoqFeTAhhcNb0HNflHvQFYEc= X-Google-Smtp-Source: ABdhPJzYx3n703PuIcGq3u41GROj2BCAhY5Xzd+yYsYj2RS0msD9GYnhwvLnd36uN9mqAOh8rAybFHzrkc1h1Dlcj2E= X-Received: by 2002:aca:d583:: with SMTP id m125mr1848352oig.47.1604994341968; Mon, 09 Nov 2020 23:45:41 -0800 (PST) MIME-Version: 1.0 References: <202010211637.7CFD8435@keescook> <773fbdb0-5fc4-ab39-e72d-89845faa4c6d@gmail.com> <202010212028.32E8A5EF9B@keescook> <1d2e2b5d-3035-238c-d2ca-14c0c209a6a1@gmail.com> <20201022161118.GP1551@shell.armlinux.org.uk> <20201022162334.GQ1551@shell.armlinux.org.uk> <20201022174826.GS1551@shell.armlinux.org.uk> In-Reply-To: From: Ard Biesheuvel Date: Tue, 10 Nov 2020 08:45:30 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v1] ARM: vfp: Use long jump to fix THUMB2 kernel compilation error To: Dmitry Osipenko Cc: Russell King - ARM Linux admin , Kees Cook , Nick Desaulniers , Linux Kernel Mailing List , clang-built-linux , Ingo Molnar , Linux ARM Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 10 Nov 2020 at 08:44, Dmitry Osipenko wrote: > > 09.11.2020 10:25, Ard Biesheuvel =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > ... > >>> So the options are > >>> > >>> a) merge my patch that adds 2 bytes of opcode to the Thumb2 build > >>> b) merge Dmitry's patch that adds an unconditional literal load to al= l builds > >>> c) remove kernel mode handling from vfp_support_entry() [my other pat= ch] > >>> d) move sections around so that vfp_kmode_exception is guaranteed to > >>> be in range. > >>> e) do nothing > ... > >> The performance argument is questionable to me, to be honest. In > >> practice the performance difference should be absolutely negligible fo= r > >> either of the proposed options, it should stay in a noise even if > >> somebody thoroughly counting cycles, IMO. > >> > >> I'm still thinking that the best option will be to apply a). > >> > > > > Can we take that as an acked-by? > > Are you asking me for the ack? Yes. > I think this is a more appropriate > question to Russel. I'm not arm/ maintainer, but could give r-b and t-b. > R-b and acked-by are basically the same thing. > If you're going to follow approach that I'm suggesting with a) + d), > then could you please resend the two patches in a single series? The > first one-line patch-fix should contain the fixes tag. Ok