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=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 B3903C43441 for ; Mon, 26 Nov 2018 10:55:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 665412089F for ; Mon, 26 Nov 2018 10:55:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="NXEOJZ0N" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 665412089F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727697AbeKZVsm (ORCPT ); Mon, 26 Nov 2018 16:48:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:57328 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726708AbeKZVsl (ORCPT ); Mon, 26 Nov 2018 16:48:41 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F17D421104; Mon, 26 Nov 2018 10:54:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543229697; bh=E3N85T6NtOYCM12ne9YIQTsCteZZrFqGAkvmgjG/YWo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NXEOJZ0NNBr84E+li/MukqSTIc8WPK35xgUiuGMpHNXiMSxd4Nxtv2MAF6WbM0oWW n9WmhdHTWUS8dFiCm0dWycaLVa0IDRLjqeyboDBuee/NVWypuVU5ZUXg1IJwWKx5Dn C1ussct5cT4taRkJ5VZwhpHCMsJJ0nGNvC12S2ws= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Matthias Kaehlcke , Arnd Bergmann , Bernhard.Rosenkranzer@linaro.org, Greg Hackmann , Kees Cook , Linus Torvalds , Masahiro Yamada , Michael Davidson , Nick Desaulniers , Peter Zijlstra , Stephen Hines , Thomas Gleixner , dianders@chromium.org, Ingo Molnar , Nathan Chancellor Subject: [PATCH 4.4 36/70] x86/build: Fix stack alignment for CLang Date: Mon, 26 Nov 2018 11:50:51 +0100 Message-Id: <20181126105050.235366120@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181126105046.722096341@linuxfoundation.org> References: <20181126105046.722096341@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Matthias Kaehlcke commit 8f91869766c00622b2eaa8ee567db4f333b78c1a upstream. Commit: d77698df39a5 ("x86/build: Specify stack alignment for clang") intended to use the same stack alignment for clang as with gcc. The two compilers use different options to configure the stack alignment (gcc: -mpreferred-stack-boundary=n, clang: -mstack-alignment=n). The above commit assumes that the clang option uses the same parameter type as gcc, i.e. that the alignment is specified as 2^n. However clang interprets the value of this option literally to use an alignment of n, in consequence the stack remains misaligned. Change the values used with -mstack-alignment to be the actual alignment instead of a power of two. cc-option isn't used here with the typical pattern of KBUILD_CFLAGS += $(call cc-option ...). The reason is that older gcc versions don't support the -mpreferred-stack-boundary option, since cc-option doesn't verify whether the alternative option is valid it would incorrectly select the clang option -mstack-alignment.. Signed-off-by: Matthias Kaehlcke Cc: Arnd Bergmann Cc: Bernhard.Rosenkranzer@linaro.org Cc: Greg Hackmann Cc: Kees Cook Cc: Linus Torvalds Cc: Masahiro Yamada Cc: Michael Davidson Cc: Nick Desaulniers Cc: Peter Zijlstra Cc: Stephen Hines Cc: Thomas Gleixner Cc: dianders@chromium.org Link: http://lkml.kernel.org/r/20170817004740.170588-1-mka@chromium.org Signed-off-by: Ingo Molnar Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman --- arch/x86/Makefile | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -14,9 +14,11 @@ endif # For gcc stack alignment is specified with -mpreferred-stack-boundary, # clang has the option -mstack-alignment for that purpose. ifneq ($(call cc-option, -mpreferred-stack-boundary=4),) - cc_stack_align_opt := -mpreferred-stack-boundary -else ifneq ($(call cc-option, -mstack-alignment=4),) - cc_stack_align_opt := -mstack-alignment + cc_stack_align4 := -mpreferred-stack-boundary=2 + cc_stack_align8 := -mpreferred-stack-boundary=3 +else ifneq ($(call cc-option, -mstack-alignment=16),) + cc_stack_align4 := -mstack-alignment=4 + cc_stack_align8 := -mstack-alignment=8 endif # How to compile the 16-bit code. Note we always compile for -march=i386; @@ -36,7 +38,7 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector) -REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align_opt)=2) +REALMODE_CFLAGS += $(cc_stack_align4) export REALMODE_CFLAGS # BITS is used as extension for files which are available in a 32 bit @@ -76,7 +78,7 @@ ifeq ($(CONFIG_X86_32),y) # Align the stack to the register width instead of using the default # alignment of 16 bytes. This reduces stack usage and the number of # alignment instructions. - KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align_opt)=2) + KBUILD_CFLAGS += $(cc_stack_align4) # Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use # a lot more stack due to the lack of sharing of stacklots: @@ -115,7 +117,7 @@ else # default alignment which keep the stack *mis*aligned. # Furthermore an alignment to the register width reduces stack usage # and the number of alignment instructions. - KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align_opt)=3) + KBUILD_CFLAGS += $(cc_stack_align8) # Use -mskip-rax-setup if supported. KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)