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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D1CA8C4332F for ; Fri, 14 Oct 2022 21:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=bg7+SD63whM5DoBeIWjA74Z82WZZMgf33Yg8bu+k90M=; b=izDd1+PW9wmsgA iIKnn/UsaGs6w9b0EOQF6cZtcrT6b/PH/KbSyOeYlGm1HOzR6VPWrNoXIudFw2CR3AoaYgTSZZHlu vfL5JqfveuRDJUjch6cuUhrB+8OKzvxKj70keq5EXtXwg7X6UAvqspjgREc9w6PQM4pQFyZxfYgkv wtDNrZPqM4WTiBruOM0gys2B+zkvDw/TLAl0Qbm6z50Bu+Ox5n70eu1tHScVKdO00Dxaby1DWJTyB JHu3LzYgjSMCK3WZT3vd8NLZffMy04HftnEWokq4k0laYN1kEZStH7F817drZS9pvZKZWBvUxlg2F 8svnLXPLSYZZyMVuQRxg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ojS7A-00FzFI-PY; Fri, 14 Oct 2022 21:21:08 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ojS78-00FzEM-48 for linux-arm-kernel@lists.infradead.org; Fri, 14 Oct 2022 21:21:07 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7B35F61B8D; Fri, 14 Oct 2022 21:21:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D8D3C433C1; Fri, 14 Oct 2022 21:21:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1665782464; bh=W830SBSAHyVTFgK+oBOpumaz6zT/ESPPX+briRUidUU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fim6nGXadK0daKWDcTjB7DuqqVbheHWqI2TI75c7Me6Bb8S3vzMN3U0upV68UhufP 1i7dZ5O2wpChIqZQ8dIRaqGak5vjcw//6u3ymWrLr5ASvqHi1OP9fhCGw1IXIRiGuB Jj/Pbgff2MKLGb9XsIkR+e/T/z8JaWIgnDbnE44NcbbyJNjMnKikDazX9GyZyienZm OcwMSL3Jfb0MAwa7tLS6E0Cd2uPt6gSOPs3C/FQxDuGaHrsRmiwL3hsQPeTr36nSph B5VbR3/aRiTs+aFh+VkfhAA4ZxcQpaZk66qpJro2r0Z9yEm5bSAZ/8Jq5tbBrgKWnG 98SFTw/7J2ndg== Date: Fri, 14 Oct 2022 14:21:02 -0700 From: Nathan Chancellor To: Nick Desaulniers Cc: Russell King , Arnd Bergmann , Ard Biesheuvel , Masahiro Yamada , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v4 4/4] ARM: pass -march= only to compiler Message-ID: References: <20221014201354.3190007-1-ndesaulniers@google.com> <20221014201354.3190007-5-ndesaulniers@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20221014201354.3190007-5-ndesaulniers@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221014_142106_264758_6590F882 X-CRM114-Status: GOOD ( 28.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 14, 2022 at 01:13:54PM -0700, Nick Desaulniers wrote: > When both -march= and -Wa,-march= are specified for assembler or > assembler-with-cpp sources, GCC and Clang will prefer the -Wa,-march= > value but Clang will warn that -march= is unused. > > warning: argument unused during compilation: '-march=armv6k' > [-Wunused-command-line-argument] > > This is the top group of warnings we observe when using clang to > assemble the kernel via `ARCH=arm make LLVM=1`. > > Split the arch-y make variable into two, so that -march= flags only get > passed to the compiler, not the assembler. -D flags are added to > KBUILD_CPPFLAGS which is used for both C and assembler-with-cpp sources. > > Clang is trying to warn that it doesn't support different values for > -march= and -Wa,-march= (like GCC does, but the kernel doesn't need this) > though the value of the preprocessor define __thumb2__ is based on > -march=. Make sure to re-set __thumb2__ via -D flag for assembler > sources now that we're no longer passing -march= to the assembler. Set > it to a different value than the preprocessor would for -march= in case > -march= gets accidentally re-added to KBUILD_AFLAGS in the future. > Thanks to Ard and Nathan for this suggestion. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1315 > Link: https://github.com/ClangBuiltLinux/linux/issues/1587 > Link: https://github.com/llvm/llvm-project/issues/55656 > Suggested-by: Ard Biesheuvel > Suggested-by: Nathan Chancellor > Signed-off-by: Nick Desaulniers This passed through my build matrix on top of commit dca45efbe3c8 ("Merge tag 'sound-fix-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound") and I saw no additional warnings/errors: Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor > --- > Changes v3 -> v4: > * Add -D__thumb2__=2 to KBUILD_AFLAGS as per in-person discussion with > Ard and Nathan, and their SB tags. > * Reword commit message. > > arch/arm/Makefile | 36 +++++++++++++++++++++++++----------- > 1 file changed, 25 insertions(+), 11 deletions(-) > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > index ee888070b2ff..b58998749ead 100644 > --- a/arch/arm/Makefile > +++ b/arch/arm/Makefile > @@ -60,21 +60,34 @@ endif > KBUILD_CFLAGS += $(call cc-option,-fno-ipa-sra) > > # This selects which instruction set is used. > +arch-$(CONFIG_CPU_32v7M) :=-march=armv7-m > +arch-$(CONFIG_CPU_32v7) :=-march=armv7-a > +arch-$(CONFIG_CPU_32v6) :=-march=armv6 > +# Only override the compiler option if ARMv6. The ARMv6K extensions are > +# always available in ARMv7 > +ifeq ($(CONFIG_CPU_32v6),y) > +arch-$(CONFIG_CPU_32v6K) :=-march=armv6k > +endif > +arch-$(CONFIG_CPU_32v5) :=-march=armv5te > +arch-$(CONFIG_CPU_32v4T) :=-march=armv4t > +arch-$(CONFIG_CPU_32v4) :=-march=armv4 > +arch-$(CONFIG_CPU_32v3) :=-march=armv3m > + > # Note that GCC does not numerically define an architecture version > # macro, but instead defines a whole series of macros which makes > # testing for a specific architecture or later rather impossible. > -arch-$(CONFIG_CPU_32v7M) :=-D__LINUX_ARM_ARCH__=7 -march=armv7-m > -arch-$(CONFIG_CPU_32v7) :=-D__LINUX_ARM_ARCH__=7 -march=armv7-a > -arch-$(CONFIG_CPU_32v6) :=-D__LINUX_ARM_ARCH__=6 -march=armv6 > -# Only override the compiler opt:ion if ARMv6. The ARMv6K extensions are > +cpp-$(CONFIG_CPU_32v7M) :=-D__LINUX_ARM_ARCH__=7 > +cpp-$(CONFIG_CPU_32v7) :=-D__LINUX_ARM_ARCH__=7 > +cpp-$(CONFIG_CPU_32v6) :=-D__LINUX_ARM_ARCH__=6 > +# Only override the compiler option if ARMv6. The ARMv6K extensions are > # always available in ARMv7 > ifeq ($(CONFIG_CPU_32v6),y) > -arch-$(CONFIG_CPU_32v6K) :=-D__LINUX_ARM_ARCH__=6 -march=armv6k > +cpp-$(CONFIG_CPU_32v6K) :=-D__LINUX_ARM_ARCH__=6 > endif > -arch-$(CONFIG_CPU_32v5) :=-D__LINUX_ARM_ARCH__=5 -march=armv5te > -arch-$(CONFIG_CPU_32v4T) :=-D__LINUX_ARM_ARCH__=4 -march=armv4t > -arch-$(CONFIG_CPU_32v4) :=-D__LINUX_ARM_ARCH__=4 -march=armv4 > -arch-$(CONFIG_CPU_32v3) :=-D__LINUX_ARM_ARCH__=3 -march=armv3m > +cpp-$(CONFIG_CPU_32v5) :=-D__LINUX_ARM_ARCH__=5 > +cpp-$(CONFIG_CPU_32v4T) :=-D__LINUX_ARM_ARCH__=4 > +cpp-$(CONFIG_CPU_32v4) :=-D__LINUX_ARM_ARCH__=4 > +cpp-$(CONFIG_CPU_32v3) :=-D__LINUX_ARM_ARCH__=3 > > # This selects how we optimise for the processor. > tune-$(CONFIG_CPU_ARM7TDMI) :=-mtune=arm7tdmi > @@ -119,15 +132,16 @@ AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W) > > ifeq ($(CONFIG_THUMB2_KERNEL),y) > CFLAGS_ISA :=-mthumb -Wa,-mimplicit-it=always $(AFLAGS_NOWARN) > -AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb > +AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb -D__thumb2__=2 > else > CFLAGS_ISA :=$(call cc-option,-marm,) $(AFLAGS_NOWARN) > AFLAGS_ISA :=$(CFLAGS_ISA) > endif > > # Need -Uarm for gcc < 3.x > +KBUILD_CPPFLAGS +=$(cpp-y) > KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -msoft-float -Uarm > -KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) -include asm/unified.h -msoft-float > +KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) -Wa,$(arch-y) $(tune-y) -include asm/unified.h -msoft-float > > CHECKFLAGS += -D__arm__ > > -- > 2.38.0.413.g74048e4d9e-goog > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel