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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2C7CC4332F for ; Fri, 14 Oct 2022 20:14:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229737AbiJNUO3 (ORCPT ); Fri, 14 Oct 2022 16:14:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231211AbiJNUOQ (ORCPT ); Fri, 14 Oct 2022 16:14:16 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C74F7186FE for ; Fri, 14 Oct 2022 13:14:15 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id p5-20020a25bd45000000b006beafa0d110so5208441ybm.1 for ; Fri, 14 Oct 2022 13:14:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=s1u5FCYn8RsWrm4xJEN7PdURIEcHyxJb/9pj2n8isAA=; b=fhvrXFoWhZpC391txksgdYNhBWOVQCBl52aYSUmgLmhInb9/MtPSZeYIGNH/ys8YWI mQSvZiXV1v5iLGTGKg3WLOnb1cFS0+Th+kedZ2Q3zmcpiIRzT5RaNzsSxxtcaNVbbxQo 6C/ki/P9jwc6ECEEO3qyZ7BhL6tV27cjhxD/VeL/TfQ+p/pKemcqLqpJM6t6JMdBSclB h82uZmMBfbIJIfgs+0ai9YWmfThqceTYpj/4W8VtdRmM96JMViT3MmTw9mDdKQfv3xvt kEinfPe2PO+UwyaMeL2LurLmXdFoE/9L88IDkDSdt7gWv/6RRC+AabmHqrVrKTq57VGh UuKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=s1u5FCYn8RsWrm4xJEN7PdURIEcHyxJb/9pj2n8isAA=; b=3S2nlx7JKYVzVjDo7mPfSqxM5pBb5R43VqxJHfsC68TcFd8HxUdNS4LU1W+Boh2WGh hq/7hBEuEKjSK/WswwftZLMEfqQMCcsxyZI+gjSxVQPNJiN43+DG6tQ8DjWKWPEG9+Ui rROqxV4Hkf2ZeUqvuCsW+BGweM1Q14OjHVIqrtT8h7mCbzJU0/CFvPRPwyOfqyzlffNs KgkbisXrYckU9CXpfr7t4UyBZjB+8mSniPirgssLygORVHfOpBq6z6b7RONHE4zd0z/p uGrq8qdARsroqAFYFvUfBotwsyQBwpZvxDGQTs3k4idgIstX7myv8rrbtCthbHgW5VfR OCCQ== X-Gm-Message-State: ACrzQf2EtC2oYpmxP09LfFQ0f0jxcDnXnPiO3u4ctTRo7W5y9nKgUZxw ZpNI1x1J9u1AxMWiV5pznPjjz52OGFhFoOLe9IU= X-Google-Smtp-Source: AMsMyM5LJchL6EFofTHHxs4MNR5XzLntxu/R6NAv2OzNylDOZxQp85yFrPbs85r8ne1/8BZAIoLHNBBM5axsYtLlCVM= X-Received: from ndesaulniers-desktop.svl.corp.google.com ([2620:0:100e:712:2ba5:63af:4077:4515]) (user=ndesaulniers job=sendgmr) by 2002:a0d:eb0d:0:b0:356:67be:73ca with SMTP id u13-20020a0deb0d000000b0035667be73camr6144943ywe.108.1665778454896; Fri, 14 Oct 2022 13:14:14 -0700 (PDT) Date: Fri, 14 Oct 2022 13:13:54 -0700 In-Reply-To: <20221014201354.3190007-1-ndesaulniers@google.com> Mime-Version: 1.0 References: <20221014201354.3190007-1-ndesaulniers@google.com> X-Developer-Key: i=ndesaulniers@google.com; a=ed25519; pk=UIrHvErwpgNbhCkRZAYSX0CFd/XFEwqX3D0xqtqjNug= X-Developer-Signature: v=1; a=ed25519-sha256; t=1665778434; l=4916; i=ndesaulniers@google.com; s=20220923; h=from:subject; bh=VxwVKVoT72n36JM/fgC34SDckwipa3adGbKwxRiCt2I=; b=rr6SNqvjfUP45yOE+YAm3SR9cD5RDQnj3V+GfQQxH8pSx9VoCaj7uytjS9DlnvEkq4VZJ0hzDBme Yv8fiIbkB02j4cJV0iSKr9y6pV5x0SIUrX0N5J9BqTNYul2wwy6r X-Mailer: git-send-email 2.38.0.413.g74048e4d9e-goog Message-ID: <20221014201354.3190007-5-ndesaulniers@google.com> Subject: [PATCH v4 4/4] ARM: pass -march= only to compiler From: Nick Desaulniers To: Russell King Cc: Arnd Bergmann , Ard Biesheuvel , Masahiro Yamada , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Nathan Chancellor , Nick Desaulniers Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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