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=-7.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 7B97DC64E7B for ; Tue, 1 Dec 2020 17:31:27 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 35E9F20870 for ; Tue, 1 Dec 2020 17:31:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="COBsdbub" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 35E9F20870 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-20473-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 11523 invoked by uid 550); 1 Dec 2020 17:31:15 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 11503 invoked from network); 1 Dec 2020 17:31:15 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=fIhrXegmFXx4Y1S8YgnbVoZcP9r/eMN50vMQw7Htjj0=; b=COBsdbubf4U1NB4bryhE6zpFJFlxC6tnZcSZU41etUauCccqXZsiquU+7Pg3YtVZk6 FaJj4o1AIWN+/OM9H6u8TAIFxZgoJVNQ/2jTBB5a/m2hHYR3qjgThVUzKnMTBTgmN/d+ qjZ/Lpe9hl7c2js/gywR+ayaeczGzpkDoU8ik= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=fIhrXegmFXx4Y1S8YgnbVoZcP9r/eMN50vMQw7Htjj0=; b=Ty1uullvzXN18/aJmcBH4jStC21CjclFYReUTBpkTNCT/PteW7jslrLn/X9Xd/nRi0 s2yICgQmWOHWI661jXYyX2v53zvDFNcMCiRUTPxLLHFjAcWqN5uNO0qdrxw8hKwL2dXd iY/vV6PrtSTz7X2a9KX/HbU+mMhrgJy3nqj9iueJ8PKVu1qCy8InSfA254H5Ohc7RJkm 4MMXU7HvQ6Bjsar77nFt4ep1Wqjlb4u1LjysCeVlv6VscTkMJXUJ6hZkqiDX+/p+olgN yQF08vcSlpVePQseFfneEbC4TKQyIedhGXpM+l9ebIgNE8MLUa1ILEA7nDg45/+g3uCc o/VA== X-Gm-Message-State: AOAM532p5aftaPfZEgh/7dpdGynEuQnWwy43dRgIPwyYGKdu+YOKVejD UB5nzXqGUECiesFZkXgN70OnIA== X-Google-Smtp-Source: ABdhPJxNXrz8lyJzMPvVj7dGfW+IUsSemW9FmHsAZMwUW4pvNI4+h4MvkJF21vQXTZU3MgV3CsB+ag== X-Received: by 2002:a17:90b:224a:: with SMTP id hk10mr3671202pjb.81.1606843863156; Tue, 01 Dec 2020 09:31:03 -0800 (PST) Date: Tue, 1 Dec 2020 09:31:00 -0800 From: Kees Cook To: Will Deacon Cc: Sami Tolvanen , Masahiro Yamada , Steven Rostedt , Josh Poimboeuf , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Nick Desaulniers , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org Subject: Re: [PATCH v7 00/17] Add support for Clang LTO Message-ID: <202012010929.3788AF5@keescook> References: <20201118220731.925424-1-samitolvanen@google.com> <20201130120130.GF24563@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201130120130.GF24563@willie-the-truck> On Mon, Nov 30, 2020 at 12:01:31PM +0000, Will Deacon wrote: > Hi Sami, > > On Wed, Nov 18, 2020 at 02:07:14PM -0800, Sami Tolvanen wrote: > > This patch series adds support for building the kernel with Clang's > > Link Time Optimization (LTO). In addition to performance, the primary > > motivation for LTO is to allow Clang's Control-Flow Integrity (CFI) to > > be used in the kernel. Google has shipped millions of Pixel devices > > running three major kernel versions with LTO+CFI since 2018. > > > > Most of the patches are build system changes for handling LLVM bitcode, > > which Clang produces with LTO instead of ELF object files, postponing > > ELF processing until a later stage, and ensuring initcall ordering. > > > > Note that v7 brings back arm64 support as Will has now staged the > > prerequisite memory ordering patches [1], and drops x86_64 while we work > > on fixing the remaining objtool warnings [2]. > > Sounds like you're going to post a v8, but that's the plan for merging > that? The arm64 parts look pretty good to me now. I haven't seen Masahiro comment on this in a while, so given the review history and its use (for years now) in Android, I will carry v8 (assuming all is fine with it) it in -next unless there are objections. -- Kees Cook