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=-11.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,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 DB676C3A59F for ; Thu, 29 Aug 2019 07:57:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7E21D2339E for ; Thu, 29 Aug 2019 07:57:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=agner.ch header.i=@agner.ch header.b="VK1CIOcB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726926AbfH2H5M (ORCPT ); Thu, 29 Aug 2019 03:57:12 -0400 Received: from mail.kmu-office.ch ([178.209.48.109]:40222 "EHLO mail.kmu-office.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725782AbfH2H5M (ORCPT ); Thu, 29 Aug 2019 03:57:12 -0400 Received: from webmail.kmu-office.ch (unknown [IPv6:2a02:418:6a02::a3]) by mail.kmu-office.ch (Postfix) with ESMTPSA id 5BBF95C061A; Thu, 29 Aug 2019 09:57:10 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=agner.ch; s=dkim; t=1567065430; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=z8mT125lg2u4srukuCuOIjTA/fSrbJ4+/sfujlxob84=; b=VK1CIOcB1OD/huRZhcJJs7rGkMfngWojEwTyYxRkZBs998yEtvOfwwRz1yi1MVI8hBPZPd gXsfuV4XFGLjWcEXKdsIIJIkXsTlIiLHfX+Sbqdb3ErBs3rMCK0qrqY65QKkQ4GQnm4DtX Unb+CFRUfzjOj4Yrg44luRuLTzZCbgU= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Date: Thu, 29 Aug 2019 09:57:10 +0200 From: Stefan Agner To: Nathan Chancellor Cc: Russell King , Nick Desaulniers , Arnd Bergmann , Matthias Kaehlcke , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH] ARM: Emit __gnu_mcount_nc when using Clang 10.0.0 or newer In-Reply-To: <20190829062635.45609-1-natechancellor@gmail.com> References: <20190829062635.45609-1-natechancellor@gmail.com> Message-ID: X-Sender: stefan@agner.ch User-Agent: Roundcube Webmail/1.3.9 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-08-29 08:26, Nathan Chancellor wrote: > Currently, multi_v7_defconfig + CONFIG_FUNCTION_TRACER fails to build > with clang: > > arm-linux-gnueabi-ld: kernel/softirq.o: in function `_local_bh_enable': > softirq.c:(.text+0x504): undefined reference to `mcount' > arm-linux-gnueabi-ld: kernel/softirq.o: in function `__local_bh_enable_ip': > softirq.c:(.text+0x58c): undefined reference to `mcount' > arm-linux-gnueabi-ld: kernel/softirq.o: in function `do_softirq': > softirq.c:(.text+0x6c8): undefined reference to `mcount' > arm-linux-gnueabi-ld: kernel/softirq.o: in function `irq_enter': > softirq.c:(.text+0x75c): undefined reference to `mcount' > arm-linux-gnueabi-ld: kernel/softirq.o: in function `irq_exit': > softirq.c:(.text+0x840): undefined reference to `mcount' > arm-linux-gnueabi-ld: kernel/softirq.o:softirq.c:(.text+0xa50): more > undefined references to `mcount' follow > > clang can emit a working mcount symbol, __gnu_mcount_nc, when > '-meabi gnu' is passed to it. Until r369147 in LLVM, this was > broken and caused the kernel not to boot because the calling > convention was not correct. Now that it is fixed, add this to > the command line when clang is 10.0.0 or newer so everything > works properly. Cool, finally function tracing with Clang :-) > > Link: https://github.com/ClangBuiltLinux/linux/issues/35 > Link: https://bugs.llvm.org/show_bug.cgi?id=33845 > Link: > https://github.com/llvm/llvm-project/commit/16fa8b09702378bacfa3d07081afe6b353b99e60 > Signed-off-by: Nathan Chancellor Reviewed-by: Stefan Agner -- Stefan > --- > arch/arm/Makefile | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > index c3624ca6c0bc..7b5a26a866fc 100644 > --- a/arch/arm/Makefile > +++ b/arch/arm/Makefile > @@ -112,6 +112,12 @@ ifeq ($(CONFIG_ARM_UNWIND),y) > CFLAGS_ABI +=-funwind-tables > endif > > +ifeq ($(CONFIG_CC_IS_CLANG),y) > +ifeq ($(shell test $(CONFIG_CLANG_VERSION) -ge 100000; echo $$?),0) > +CFLAGS_ABI +=-meabi gnu > +endif > +endif > + > # Accept old syntax despite ".syntax unified" > AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W)