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=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 50B61C55ABD for ; Sat, 14 Nov 2020 01:59:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B8E92224F for ; Sat, 14 Nov 2020 01:59:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ik4yw2YT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726163AbgKNB7M (ORCPT ); Fri, 13 Nov 2020 20:59:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725981AbgKNB7M (ORCPT ); Fri, 13 Nov 2020 20:59:12 -0500 Received: from mail-yb1-xb42.google.com (mail-yb1-xb42.google.com [IPv6:2607:f8b0:4864:20::b42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1BE2BC0613D1 for ; Fri, 13 Nov 2020 17:59:11 -0800 (PST) Received: by mail-yb1-xb42.google.com with SMTP id 10so10426558ybx.9 for ; Fri, 13 Nov 2020 17:59:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7r0K5AbepHsDaPF3+eWVWgzKdiDEkcQlLcEm/Htya0k=; b=ik4yw2YTizvMDpWbg2ZKKO0p6k4tgceG5tr16xg+ZEGuZIZvvu2VwRCV0r28AwSZkE n8ZuwuolIDU7VdBiv3wrEiJ5LfCpBt2UB2vhowX9d2L7Sid+Xi7sizi2CB/WuZqYIiLH 9ziDeQlg+YG/GUL5vfMZ6TCLKG32ZonkbMaDmjedZvSjiYqolaJTOWxhS4Pua2MBtkPU n1vft/gunIAkPsysmpHi/FAMWhHBAfhXTtO2L1jPrDAsXMPx/mOKb2RIM31CDowNg9Iz 0YlW3qbARsdumtUbVBRgJLJnQLJ0WLU4YOcvTJJFgFjVLphEdb7Tk/GYO0kUhrl8HgDI Hekg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7r0K5AbepHsDaPF3+eWVWgzKdiDEkcQlLcEm/Htya0k=; b=bgRPQ/ueSb/25sfWDjT+LfOEUJcUPJud+ILKnvActtjRuRQ4ypDRuI8pcJKma3IEiE 0jzeezaoY/eGKxJuMbB4PhyFUhnNwzLAF0lGqg3/KxYsI4A4OKEH9RWJ07OMvuZgfMU/ Xp60z0vG5EMshfU22Tt5Vp+IYN0vY3Ny5CMRvJUKTPcNuFYWK4jcg4LLPKFmRlm/HbCd 5ftqfuzDbfFi/hXQov0mFxKkjQjEGqwSQuWQdUGhSeM3qbkayLTtdIQphrksGDUlMUfT /FPtmvMRv1Db1Y8SpoDrM0KyQAMGYjIvz+X1qb/INHj/sG/UjzgaZ/Vb4tmNC4gR9Ig7 mp6w== X-Gm-Message-State: AOAM5311azGCuoCpW4VW0kDs5USuT/LBJfKLsWe9RT0tnfyWmMYgtknB 2b2NC2O2GrzCFHb7UHrCu1TEu1SO09wkS87HH3+p/dvr X-Google-Smtp-Source: ABdhPJxaqIQoAXd/MhdpfwHnB6o3iezX4TTFb2U3TSYz8pOXZxcvwyd4jZdzy07/erbCg6tIZOG/CDPNMc3ebIoMCS0= X-Received: by 2002:a25:5f0f:: with SMTP id t15mr5791894ybb.26.1605319150351; Fri, 13 Nov 2020 17:59:10 -0800 (PST) MIME-Version: 1.0 References: <20201109144425.270789-22-alexandre.chartre@oracle.com> <202011131552.4kvOb9Id-lkp@intel.com> <20201113234701.GV2672@gate.crashing.org> <20201114002624.GX2672@gate.crashing.org> In-Reply-To: <20201114002624.GX2672@gate.crashing.org> From: Miguel Ojeda Date: Sat, 14 Nov 2020 02:58:59 +0100 Message-ID: Subject: Re: [RFC][PATCH 21/24] x86/entry: Disable stack-protector for IST entry C handlers To: Segher Boessenkool Cc: Nick Desaulniers , Alexandre Chartre , kbuild-all@lists.01.org, clang-built-linux , linux-toolchains@vger.kernel.org, kernel test robot , Arvind Sankar , Ard Biesheuvel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-toolchains@vger.kernel.org On Sat, Nov 14, 2020 at 1:27 AM Segher Boessenkool wrote: > > But you cannot limit yourself to the greatest common denominator: the > kernel wants to use many features only available on newer compiler > versions, too; this is no different. What we do is conditionally enable both new and differentiating features. We don't break GCC or LLVM just because the other introduces a new shiny feature, nor we break builds with old compilers (except when raising the minimum supported version). That is why we need a level of indirection in things like attributes nowadays, and why patches like the above are not ideal anymore (regardless of which attribute we are talking about). Cheers, Miguel