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=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 F3E3EC64E90 for ; Mon, 30 Nov 2020 12:02:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D5A02222A for ; Mon, 30 Nov 2020 12:02:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="EwVQLNws" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729170AbgK3MCS (ORCPT ); Mon, 30 Nov 2020 07:02:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:35772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727656AbgK3MCS (ORCPT ); Mon, 30 Nov 2020 07:02:18 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 89B91206CB; Mon, 30 Nov 2020 12:01:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606737697; bh=A/tQpaRCdVBxIrK5CVrihAXJGL1D0YMcA4iympcoTzk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EwVQLNwsXH/bdnWP/eU1At5WBpjCSdAR6JTRNITU+0kyAYmyC7vfvCGB5aglCFG6x MgF+azWjp5V9E9RCzfCIxmq6AyuSMIhVSOBmKKJ8jGetiIbmZ9+phj0IYAntF8L2n+ Jz+cOfBAzUsJpOu6/EZ4Jj48GG8LJpvvDpy7mI9s= Date: Mon, 30 Nov 2020 12:01:31 +0000 From: Will Deacon To: Sami Tolvanen Cc: Masahiro Yamada , Steven Rostedt , Josh Poimboeuf , Peter Zijlstra , Greg Kroah-Hartman , "Paul E. McKenney" , Kees Cook , 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: <20201130120130.GF24563@willie-the-truck> References: <20201118220731.925424-1-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201118220731.925424-1-samitolvanen@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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. Will