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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 51B9FC433DF for ; Wed, 24 Jun 2020 21:27:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F98320857 for ; Wed, 24 Jun 2020 21:27:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="kW0Gs+LL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390530AbgFXV16 (ORCPT ); Wed, 24 Jun 2020 17:27:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390437AbgFXV16 (ORCPT ); Wed, 24 Jun 2020 17:27:58 -0400 Received: from casper.infradead.org (unknown [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DBAC1C061573; Wed, 24 Jun 2020 14:27:57 -0700 (PDT) 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=dcJg1Pmd9f78D6vA5vvd8lv5yiCcj7aT/KXUxx3p85w=; b=kW0Gs+LLCGSOFq3lO7r9YinA6h 7xtahaSI1ma1wfxrkYodfw/iXU/zbFsJzgSO5Db8M5Kas3qE60Cck9uyn4jrjlZvm4WgRzqG9Ooo+ jtCEqqSNm9W5tIGaN1elclBZcSfEZNv5jg8vAcfn+g1UJT8QHR4RwlPAuZfIuPNkOQap4e1qGfV0A cwt7PlLLvNImzMirpJd7/CDVC+M0Z9FaI9SC337TdLUSsHDB1EA/Z6q2MQrf71QVeEPDP0jb3OvhT EYDKEdVRjSgNUEKkA9mDDp6z8eth0zsksmz5WswtilA7uOUEs9S8I39JpTCT+viS29bezWW7uDl75 mvKP2izA==; 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 1joCvi-0004ro-5P; Wed, 24 Jun 2020 21:27:38 +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 B90E3300261; Wed, 24 Jun 2020 23:27:37 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A61A722B8EBE8; Wed, 24 Jun 2020 23:27:37 +0200 (CEST) Date: Wed, 24 Jun 2020 23:27:37 +0200 From: Peter Zijlstra To: Sami Tolvanen Cc: Masahiro Yamada , Will Deacon , 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, x86@kernel.org Subject: Re: [PATCH 04/22] kbuild: lto: fix recordmcount Message-ID: <20200624212737.GV4817@hirez.programming.kicks-ass.net> References: <20200624203200.78870-1-samitolvanen@google.com> <20200624203200.78870-5-samitolvanen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200624203200.78870-5-samitolvanen@google.com> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, Jun 24, 2020 at 01:31:42PM -0700, Sami Tolvanen wrote: > With LTO, LLVM bitcode won't be compiled into native code until > modpost_link. This change postpones calls to recordmcount until after > this step. > > In order to exclude specific functions from inspection, we add a new > code section .text..nomcount, which we tell recordmcount to ignore, and > a __nomcount attribute for moving functions to this section. I'm confused, you only add this to functions in ftrace itself, which is compiled with: KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS)) and so should not have mcount/fentry sites anyway. So what's the point of ignoring them further? This Changelog does not explain.