From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753556AbeFAQ4E (ORCPT ); Fri, 1 Jun 2018 12:56:04 -0400 Received: from mail-pl0-f66.google.com ([209.85.160.66]:35797 "EHLO mail-pl0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753199AbeFAQz6 (ORCPT ); Fri, 1 Jun 2018 12:55:58 -0400 X-Google-Smtp-Source: ADUXVKLsLuudchKT9coQ+jCWZRdH2mEmPFH4ht90v3Mj7rwHxCciG/Ff2VBi1jIWkPWIi/PTmQp93A== From: Nick Desaulniers To: akpm@linux-foundation.org, ard.biesheuvel@linaro.org, aryabinin@virtuozzo.com, akataria@vmware.com, boris.ostrovsky@oracle.com, brijesh.singh@amd.com, caoj.fnst@cn.fujitsu.com, gregkh@linuxfoundation.org, hpa@zytor.com, jan.kiszka@siemens.com, jarkko.sakkinen@linux.intel.com, jgross@suse.com, jpoimboe@redhat.com, kirill.shutemov@linux.intel.com, mingo@redhat.com, mjg59@google.com, mka@chromium.org, ndesaulniers@google.com, pombredanne@nexb.com, rostedt@goodmis.org, tglx@linutronix.de, thomas.lendacky@amd.com, tweek@google.com Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH 1/3] efi: use -std=gnu89 for proper extern inline semantics Date: Fri, 1 Jun 2018 09:55:48 -0700 Message-Id: <20180601165550.90053-2-ndesaulniers@google.com> X-Mailer: git-send-email 2.17.0.921.gf22659ad46-goog In-Reply-To: <20180601165550.90053-1-ndesaulniers@google.com> References: <20180601165550.90053-1-ndesaulniers@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The top level Makefile explicitly sets the C standard used in the kernel to gnu89. By overriding KBUILD_CFLAGS, the C standard used for this subdir is now implicit based on compiler and compiler version. GCC changes this implicit default from gnu89 to gnu11 in v5.1. This implies that depending on compiler version, parts of the kernel are being linked together from object files that were compiled with different C standard compiler flags. This is problematic for symbols declared as extern inline, as the semantics have switched since gnu89. See also: http://blahg.josefsipek.net/?p=529 Signed-off-by: Nick Desaulniers Suggested-by: Sedat Dilek Tested-by: Sedat Dilek --- drivers/firmware/efi/libstub/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index a34e9290a699..97ca53ab2b69 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -7,7 +7,7 @@ # cflags-$(CONFIG_X86_32) := -march=i386 cflags-$(CONFIG_X86_64) := -mcmodel=small -cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -O2 \ +cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ -O2 -std=gnu89 \ -fPIC -fno-strict-aliasing -mno-red-zone \ -mno-mmx -mno-sse -fshort-wchar -- 2.17.0.921.gf22659ad46-goog