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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 C20E9C43387 for ; Wed, 19 Dec 2018 16:54:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99E64214C6 for ; Wed, 19 Dec 2018 16:54:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729692AbeLSQyf (ORCPT ); Wed, 19 Dec 2018 11:54:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43276 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727589AbeLSQye (ORCPT ); Wed, 19 Dec 2018 11:54:34 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AC2A8C070E19; Wed, 19 Dec 2018 16:54:33 +0000 (UTC) Received: from treble (ovpn-120-179.rdu2.redhat.com [10.10.120.179]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2EBD55D6A9; Wed, 19 Dec 2018 16:54:30 +0000 (UTC) Date: Wed, 19 Dec 2018 10:54:28 -0600 From: Josh Poimboeuf To: Miroslav Benes Cc: yamada.masahiro@socionext.com, michal.lkml@markovi.net, jeyu@kernel.org, jikos@kernel.org, pmladek@suse.com, linux-kbuild@vger.kernel.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kbuild: use -flive-patching when CONFIG_LIVEPATCH is enabled Message-ID: <20181219165428.5udrppedpdvf2u7k@treble> References: <20181219141744.32392-1-mbenes@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181219141744.32392-1-mbenes@suse.cz> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 19 Dec 2018 16:54:34 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 19, 2018 at 03:17:44PM +0100, Miroslav Benes wrote: > GCC 9 introduces a new option, -flive-patching. It disables certain > optimizations which could make a compilation unsafe for later live > patching of the running kernel. > > The option is used only if CONFIG_LIVEPATCH is enabled and $(CC) > supports it. > > Signed-off-by: Miroslav Benes > --- > Makefile | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Makefile b/Makefile > index a0650bf79606..53f5ab810efe 100644 > --- a/Makefile > +++ b/Makefile > @@ -778,6 +778,10 @@ KBUILD_CFLAGS_KERNEL += $(call cc-option,-ffunction-sections,) > KBUILD_CFLAGS_KERNEL += $(call cc-option,-fdata-sections,) > endif > > +ifdef CONFIG_LIVEPATCH > +KBUILD_CFLAGS += $(call cc-option, -flive-patching=inline-clone) > +endif > + > # arch Makefile may override CC so keep this after arch Makefile is included > NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) This option only makes sense for source-based patch generation, so isn't it a bit premature to make this change without proper source-based patch tooling? Also the commit message needs an analysis of the performance impacts. -- Josh