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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 22424C46464 for ; Tue, 14 Aug 2018 08:34:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D505B217BC for ; Tue, 14 Aug 2018 08:34:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D505B217BC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731015AbeHNLUE (ORCPT ); Tue, 14 Aug 2018 07:20:04 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:39910 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728483AbeHNLUE (ORCPT ); Tue, 14 Aug 2018 07:20:04 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 075A180D; Tue, 14 Aug 2018 01:33:56 -0700 (PDT) Received: from [10.4.13.92] (e112298-lin.emea.arm.com [10.4.13.92]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 37ED93F5D0; Tue, 14 Aug 2018 01:33:54 -0700 (PDT) Subject: Re: [PATCH 1/3] arm64: implement ftrace with regs To: Steven Rostedt Cc: Torsten Duwe , Will Deacon , Catalin Marinas , Ingo Molnar , Ard Biesheuvel , Arnd Bergmann , AKASHI Takahiro , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org References: <20180810160043.9E45568C76@newverein.lst.de> <20180810160223.D360D68C76@newverein.lst.de> <2b5c1092-2cc0-00ec-ba3d-341dc61452b4@arm.com> <20180813220315.6e8dfc9c@vmware.local.home> From: Julien Thierry Message-ID: Date: Tue, 14 Aug 2018 09:33:52 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180813220315.6e8dfc9c@vmware.local.home> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/08/18 03:03, Steven Rostedt wrote: > On Mon, 13 Aug 2018 11:54:06 +0100 > Julien Thierry wrote: > >>> --- a/arch/arm64/Makefile >>> +++ b/arch/arm64/Makefile >>> @@ -78,6 +78,15 @@ ifeq ($(CONFIG_ARM64_MODULE_PLTS),y) >>> KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/arm64/kernel/module.lds >>> endif >>> >>> +ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS >>> + CC_FLAGS_FTRACE := -fpatchable-function-entry=2 >>> + KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY >>> + ifeq ($(call cc-option,-fpatchable-function-entry=2),) >>> + $(warning Cannot use CONFIG_DYNAMIC_FTRACE_WITH_REGS: \ >>> + -fpatchable-function-entry not supported by compiler) >> >> Shouldn't this be an error? The option -fpatchable-function-entry has >> been added to the CC_FLAGS_FTRACE, so any call to the compiler is gonna >> break anyway. Or am I missing something? > > I'm guessing this adds a more informative message on that error. One > will know why -fpatchable-function-entry was added to the CFLAGS. I'm > for more informative error messages being a victim of poor error > messages causing me to dig deep into the guts of the build > infrastructure to figure out simple issues. > Yes, I agree it is better to have this message. My point was that we could have "$error" instead of "$warning" to stop the compilation right away since we know everything is gonna break (and on parallel builds this warning is gonna be drowned in compiler errors). -- Julien Thierry