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=-14.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 CED99C32750 for ; Fri, 2 Aug 2019 09:48:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A791D206A2 for ; Fri, 2 Aug 2019 09:48:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739306; bh=ddcEfqeo6v3OSjK2Q2P8/JvVXUdCv5mMfd3jq3ExwGA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OTcSoHjWqkgdOcQJXbcdZx4oJXFqhZjU8ryr8KW3Ls8Irjc7O8CssUfIK19uMQn3r P1sLryOqRbPdt1UEpBCx9q44Nulluo6HnihYfhXjuq94pdXTWmb8RWrMzkrT65Hmdg 3zp/F/thDSWh5M+CbEPX7HZifUq1jK5czJzLnzSc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405823AbfHBJsN (ORCPT ); Fri, 2 Aug 2019 05:48:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:53552 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405817AbfHBJsN (ORCPT ); Fri, 2 Aug 2019 05:48:13 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D9D3F20880; Fri, 2 Aug 2019 09:48:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739292; bh=ddcEfqeo6v3OSjK2Q2P8/JvVXUdCv5mMfd3jq3ExwGA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tD/78nnJTYVwZjWhgxXML2KpOngaWJMffUd7WcvVEZQ9TOowM3+8ahOGhYNQ8Qvkj 3qzxEVYRhfk0nWtW6O/PWzR2uwTDTZa82B1gLO7/uXfBslyP4XkVVj28qgmNaBnw4R tdR3XevltTVzGrVy6liPUMvwq6Ay7TGArHpew8Pg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Smith , Nathan Chancellor , Nick Desaulniers , Masahiro Yamada , Sasha Levin Subject: [PATCH 4.9 177/223] kbuild: Add -Werror=unknown-warning-option to CLANG_FLAGS Date: Fri, 2 Aug 2019 11:36:42 +0200 Message-Id: <20190802092249.235107260@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092238.692035242@linuxfoundation.org> References: <20190802092238.692035242@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit 589834b3a0097a4908f4112eac0ca2feb486fa32 ] In commit ebcc5928c5d9 ("arm64: Silence gcc warnings about arch ABI drift"), the arm64 Makefile added -Wno-psabi to KBUILD_CFLAGS, which is a GCC only option so clang rightfully complains: warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option] https://clang.llvm.org/docs/DiagnosticsReference.html#wunknown-warning-option However, by default, this is merely a warning so the build happily goes on with a slew of these warnings in the process. Commit c3f0d0bc5b01 ("kbuild, LLVMLinux: Add -Werror to cc-option to support clang") worked around this behavior in cc-option by adding -Werror so that unknown flags cause an error. However, this all happens silently and when an unknown flag is added to the build unconditionally like -Wno-psabi, cc-option will always fail because there is always an unknown flag in the list of flags. This manifested as link time failures in the arm64 libstub because -fno-stack-protector didn't get added to KBUILD_CFLAGS. To avoid these weird cryptic failures in the future, make clang behave like gcc and immediately error when it encounters an unknown flag by adding -Werror=unknown-warning-option to CLANG_FLAGS. This can be added unconditionally for clang because it is supported by at least 3.0.0, according to godbolt [1] and 4.0.0, according to its documentation [2], which is far earlier than we typically support. [1]: https://godbolt.org/z/7F7rm3 [2]: https://releases.llvm.org/4.0.0/tools/clang/docs/DiagnosticsReference.html#wunknown-warning-option Link: https://github.com/ClangBuiltLinux/linux/issues/511 Link: https://github.com/ClangBuiltLinux/linux/issues/517 Suggested-by: Peter Smith Signed-off-by: Nathan Chancellor Tested-by: Nick Desaulniers Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin --- Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/Makefile b/Makefile index 1ab22a85118f..03ff09d789b4 100644 --- a/Makefile +++ b/Makefile @@ -515,6 +515,7 @@ ifneq ($(GCC_TOOLCHAIN),) CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN) endif CLANG_FLAGS += -no-integrated-as +CLANG_FLAGS += -Werror=unknown-warning-option KBUILD_CFLAGS += $(CLANG_FLAGS) KBUILD_AFLAGS += $(CLANG_FLAGS) endif -- 2.20.1