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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 5A443C433E0 for ; Wed, 24 Jun 2020 21:17:31 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 28B3C20768 for ; Wed, 24 Jun 2020 21:17:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="GZEZHjAF"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="lvI0AvNC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 28B3C20768 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=U1gCAwICd6i05Vdip498RS+XMSP0tAkRoZ0cldk04qM=; b=GZEZHjAFS3QXIHPTDpofrFF18 CWAesWTrtIJLwa+u5ziQQkCVRmHF4Wc3vgboJz5J3erxv2OU1tRtv6AZtyQQ6afjFp+hm6n+2fbAm dGwydjy2mEWb+lUvKdzkev4JnLLbOVKtFhUZvPv3xhbTEMw1HFy5D6Z0Xm0jM7Wvf/8IzAjfd5bnT 2mKFI+lzQQdN+8JawK88uWGemkDTNzZfpZISviKfDKsApSZZRJ/KNMYaFePtLAQjpjIcqcmtoBUXE Ra5vSpofuppfCe3bgoe0HtclDhF/SCj2ZWuusBUFaTg8MeQxIY8ftEXpFXzaaeGYtNls7CRruTm+M hpTvCG2Bw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1joCkF-0002e9-U5; Wed, 24 Jun 2020 21:15:47 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1joCkD-0002dQ-PY for linux-arm-kernel@merlin.infradead.org; Wed, 24 Jun 2020 21:15:45 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=CYAOBdXXwk5atGG1OkexemEOJEg2uOXvmf8MxtMHkzA=; b=lvI0AvNCOyQRFPEBPSO732MCmS priyMdaeyT9DlHRLc/z9qWhkeCY/G37ozS6HciR55B+xdk3sRO+bn4RdzWVJS4FDFf++roys12UFi 2Xn0aJcu82shXhcuPUJaxr0NiofjiM9cS72P+0UyExr/CWjZItZDE4OZMDMLf4RBiQ+3eGs0RrR20 QerCqnR4yK+D/eqXSR/BaYzSzLfSMZBayOvuxe0uMIgumCmxbS4aKn+HlmJxHDAjxC7KlQlu9/mMK D//TxmU24AKwnTz6mvW3vYpxg3iJ7ar26Kv6tNzbCv4aRAJOYWk+gjYHLWLDLC4v2if3/bM+oS2fR WOLeUYeg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1joCkB-0004Ne-TF; Wed, 24 Jun 2020 21:15:44 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 1283B304B6D; Wed, 24 Jun 2020 23:15:41 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 05648203CDC3F; Wed, 24 Jun 2020 23:15:41 +0200 (CEST) Date: Wed, 24 Jun 2020 23:15:40 +0200 From: Peter Zijlstra To: Sami Tolvanen Subject: Re: [PATCH 00/22] add support for Clang LTO Message-ID: <20200624211540.GS4817@hirez.programming.kicks-ass.net> References: <20200624203200.78870-1-samitolvanen@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200624203200.78870-1-samitolvanen@google.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, x86@kernel.org, Kees Cook , "Paul E. McKenney" , kernel-hardening@lists.openwall.com, Greg Kroah-Hartman , Masahiro Yamada , linux-kbuild@vger.kernel.org, Nick Desaulniers , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-pci@vger.kernel.org, Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jun 24, 2020 at 01:31:38PM -0700, Sami Tolvanen wrote: > This patch series adds support for building x86_64 and arm64 kernels > 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's > Pixel devices have shipped with LTO+CFI kernels 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 first objtool patch in the series is already in linux-next, > but as it's needed with LTO, I'm including it also here to make testing > easier. I'm very sad that yet again, memory ordering isn't addressed. LTO vastly increases the range of the optimizer to wreck things. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel