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=-15.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 F0B6AC76195 for ; Fri, 19 Jul 2019 04:25:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4A4020873 for ; Fri, 19 Jul 2019 04:25:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563510319; bh=neUiaw9I+ayq8rHPA4uNM0yvFTPnN6ucjHMEctQ77LM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=pwoqz2jI2WCfd3frgMEjHYkxO/bZRi5PQyrOSRjXOZd2qMOivPnBPw5lwDNzikTXy F8kko8GmQKDy+wf1deOHeWfzmQvr3SC5ztjNitMy7xlMo3C+bISEql+enqx31zJZSh XMrQxGWCi9KYpXll3ygdJ+mEkACxoEHdDX97ZE9Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388233AbfGSEZS (ORCPT ); Fri, 19 Jul 2019 00:25:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:43530 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730679AbfGSEJE (ORCPT ); Fri, 19 Jul 2019 00:09:04 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7162C218BB; Fri, 19 Jul 2019 04:09:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563509343; bh=neUiaw9I+ayq8rHPA4uNM0yvFTPnN6ucjHMEctQ77LM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GZHi5dMTrEkYccA3V9EPk3edyxnVhcca8LBGXv8DTKf774kQkJuQFRtaJUrgB53lQ lNQPZKJO4lcMxiJVmB+sEhohPhV0BXfveL6GWrROzzwKnXVdavT7uqGWy19XWVpuyw 7TMW2gXUPSt/vRCSRtTh7Ktj1k4k8bTJXvka/yCM= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Nathan Chancellor , Peter Smith , Nick Desaulniers , Masahiro Yamada , Sasha Levin , linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH AUTOSEL 4.19 044/101] kbuild: Add -Werror=unknown-warning-option to CLANG_FLAGS Date: Fri, 19 Jul 2019 00:06:35 -0400 Message-Id: <20190719040732.17285-44-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190719040732.17285-1-sashal@kernel.org> References: <20190719040732.17285-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nathan Chancellor [ 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 38f2150457fd..d439ccd564ca 100644 --- a/Makefile +++ b/Makefile @@ -491,6 +491,7 @@ 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) export CLANG_FLAGS -- 2.20.1