From patchwork Tue Jan 31 10:58:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 13122878 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 1C8A7C636CC for ; Tue, 31 Jan 2023 11:00:00 +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:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=urGAol/1BaEIQ4TZqEfviaE0MoVaxsCsMaN3IUlWeUY=; b=koE73QiW9J0hYP CN1hsj59PRLNr8Pxfpy2Z9UKeVGzr3yZMSoN40QCAnY3vCud5tsgXfmk7yc9nrJsvud5aYJhMzyoB McNgzqRXG/i3KmaU6x6/bFdXOlJiSrhsJmyDFe/+p5K71WKbtXJ+TyYawfjxx0oTrYLweYTAtJPar imzHIKU4hQO+JaDsmOCPphHSGrozbIO0a9vq42LD+OuVfYlGkhyYEsdT3OEzA5n1Hr/BrlizDYkmz qX6PJ3KsSq0X8naL5VnMTSy0KUerY43Sr89/CNvgVlLrSKeM3fu8Wp8Oo+M9z17I5RuoiErfaBCqe xzo8+DeKAfMCw4RAbnZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pMoLp-007bug-Iw; Tue, 31 Jan 2023 10:58:57 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pMoLD-007beO-GD for linux-arm-kernel@lists.infradead.org; Tue, 31 Jan 2023 10:58:22 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 376041713; Tue, 31 Jan 2023 02:58:58 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 2C2E73F71E; Tue, 31 Jan 2023 02:58:15 -0800 (PST) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: amit.kachhap@arm.com, ardb@kernel.org, broonie@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, will@kernel.org Subject: [PATCH v2 1/2] arm64: unify asm-arch manipulation Date: Tue, 31 Jan 2023 10:58:08 +0000 Message-Id: <20230131105809.991288-2-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230131105809.991288-1-mark.rutland@arm.com> References: <20230131105809.991288-1-mark.rutland@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230131_025819_704000_43841B4A X-CRM114-Status: GOOD ( 18.51 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Assemblers will reject instructions not supported by a target architecture version, and so we must explicitly tell the assembler the latest architecture version for which we want to assemble instructions from. We've added a few AS_HAS_ARMV8_ definitions for this, in addition to an inconsistently named AS_HAS_PAC definition, from which arm64's top-level Makefile determines the architecture version that we intend to target, and generates the `asm-arch` variable. To make this a bit clearer and easier to maintain, this patch reworks the Makefile to determine asm-arch in a single if-else-endif chain. AS_HAS_PAC, which is defined when the assembler supports `-march=armv8.3-a`, is renamed to AS_HAS_ARMV8_3. As the logic for armv8.3-a is lifted out of the block handling pointer authentication, `asm-arch` may now be set to armv8.3-a regardless of whether support for pointer authentication is selected. This means that it will be possible to assemble armv8.3-a instructions even if we didn't intend to, but this is consistent with our handling of other architecture versions, and the compiler won't generate armv8.3-a instructions regardless. For the moment there's no need for an CONFIG_AS_HAS_ARMV8_1, as the code for LSE atomics and LDAPR use individual `.arch_extension` entries and do not require the baseline asm arch to be bumped to armv8.1-a. The other armv8.1-a features (e.g. PAN) do not require assembler support. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Reviewed-by: Ard Biesheuvel Reviewed-by: Mark Brown Cc: Catalin Marinas Cc: Will Deacon --- arch/arm64/Kconfig | 4 ++-- arch/arm64/Makefile | 37 ++++++++++++++++++------------------- 2 files changed, 20 insertions(+), 21 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 03934808b2ed..be760ad7715d 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1818,7 +1818,7 @@ config ARM64_PTR_AUTH_KERNEL bool "Use pointer authentication for kernel" default y depends on ARM64_PTR_AUTH - depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_PAC + depends on (CC_HAS_SIGN_RETURN_ADDRESS || CC_HAS_BRANCH_PROT_PAC_RET) && AS_HAS_ARMV8_3 # Modern compilers insert a .note.gnu.property section note for PAC # which is only understood by binutils starting with version 2.33.1. depends on LD_IS_LLD || LD_VERSION >= 23301 || (CC_IS_GCC && GCC_VERSION < 90100) @@ -1843,7 +1843,7 @@ config CC_HAS_SIGN_RETURN_ADDRESS # GCC 7, 8 def_bool $(cc-option,-msign-return-address=all) -config AS_HAS_PAC +config AS_HAS_ARMV8_3 def_bool $(cc-option,-Wa$(comma)-march=armv8.3-a) config AS_HAS_CFI_NEGATE_RA_STATE diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index d62bd221828f..e176eb76345b 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -63,11 +63,6 @@ stack_protector_prepare: prepare0 include/generated/asm-offsets.h)) endif -ifeq ($(CONFIG_AS_HAS_ARMV8_2), y) -# make sure to pass the newest target architecture to -march. -asm-arch := armv8.2-a -endif - # Ensure that if the compiler supports branch protection we default it # off, this will be overridden if we are using branch protection. branch-prot-flags-y += $(call cc-option,-mbranch-protection=none) @@ -88,25 +83,29 @@ branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET_BTI) := -mbranch-protectio else branch-prot-flags-$(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET) := -mbranch-protection=$(PACRET-y) endif -# -march=armv8.3-a enables the non-nops instructions for PAC, to avoid the -# compiler to generate them and consequently to break the single image contract -# we pass it only to the assembler. This option is utilized only in case of non -# integrated assemblers. -ifeq ($(CONFIG_AS_HAS_PAC), y) -asm-arch := armv8.3-a -endif endif KBUILD_CFLAGS += $(branch-prot-flags-y) -ifeq ($(CONFIG_AS_HAS_ARMV8_4), y) -# make sure to pass the newest target architecture to -march. -asm-arch := armv8.4-a -endif - +# Tell the assembler to support instructions from the latest target +# architecture. +# +# For non-integrated assemblers we'll pass this on the command line, and for +# integrated assemblers we'll define ARM64_ASM_ARCH and ARM64_ASM_PREAMBLE for +# inline usage. +# +# We cannot pass the same arch flag to the compiler as this would allow it to +# freely generate instructions which are not supported by earlier architecture +# versions, which would prevent a single kernel image from working on earlier +# hardware. ifeq ($(CONFIG_AS_HAS_ARMV8_5), y) -# make sure to pass the newest target architecture to -march. -asm-arch := armv8.5-a + asm-arch := armv8.5-a +else ifeq ($(CONFIG_AS_HAS_ARMV8_4), y) + asm-arch := armv8.4-a +else ifeq ($(CONFIG_AS_HAS_ARMV8_3), y) + asm-arch := armv8.3-a +else ifeq ($(CONFIG_AS_HAS_ARMV8_2), y) + asm-arch := armv8.2-a endif ifdef asm-arch