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=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 08F0FC64E69 for ; Fri, 20 Nov 2020 04:05:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F20522400 for ; Fri, 20 Nov 2020 04:05:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QAJ7dC+j" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726515AbgKTEEj (ORCPT ); Thu, 19 Nov 2020 23:04:39 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:40750 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725944AbgKTEEi (ORCPT ); Thu, 19 Nov 2020 23:04:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605845077; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=o2KUuc5wwsBwxaFKsqE+AT6g8ZgQDPHa1BC4D1RcHko=; b=QAJ7dC+jIYsdyzBghu3FHiqv+OL8V9WfweQXvabDm0BuyD2fUVodeXv9ZSzivR3XgbNV/9 zHJUJxTdFwFOenytSIrWixG0LeCLX+vakVbyd9H9RKRHaz7jpzN0vIdQ84bnrJGoWlABzE 7UQhpSn87Kq+F1ruZxfdoTXRYHzCfsc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-230-yDf3VGw1POqCQOhtPJpkwQ-1; Thu, 19 Nov 2020 23:04:33 -0500 X-MC-Unique: yDf3VGw1POqCQOhtPJpkwQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 126894236B; Fri, 20 Nov 2020 04:04:31 +0000 (UTC) Received: from treble (ovpn-119-150.rdu2.redhat.com [10.10.119.150]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 90D3019C47; Fri, 20 Nov 2020 04:04:27 +0000 (UTC) Date: Thu, 19 Nov 2020 22:04:24 -0600 From: Josh Poimboeuf To: Sami Tolvanen Cc: Masahiro Yamada , Steven Rostedt , Will Deacon , 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: <20201120040424.a3wctajzft4ufoiw@treble> References: <20201118220731.925424-1-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201118220731.925424-1-samitolvanen@google.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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]. Sami, Here are some patches to fix the objtool issues (other than crypto which I'll work on next). https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git objtool-vmlinux -- Josh