From patchwork Mon Oct 24 17:32:30 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sven Joachim X-Patchwork-Id: 9392727 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4057060762 for ; Mon, 24 Oct 2016 17:33:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 33ADC291C5 for ; Mon, 24 Oct 2016 17:33:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2552F291CD; Mon, 24 Oct 2016 17:33:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,FREEMAIL_FROM, RCVD_IN_DNSWL_HI,T_TVD_MIME_EPI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7F0F2291C5 for ; Mon, 24 Oct 2016 17:33:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751292AbcJXRdX (ORCPT ); Mon, 24 Oct 2016 13:33:23 -0400 Received: from mout.gmx.net ([212.227.17.22]:51524 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750747AbcJXRdX (ORCPT ); Mon, 24 Oct 2016 13:33:23 -0400 Received: from localhost.localdomain ([91.19.51.98]) by mail.gmx.com (mrgmx102) with ESMTPSA (Nemesis) id 0Li1hG-1cklQf0o3m-00n7Ag; Mon, 24 Oct 2016 19:32:35 +0200 Received: by localhost.localdomain (Postfix, from userid 1000) id E29083F38B; Mon, 24 Oct 2016 19:32:30 +0200 (CEST) From: Sven Joachim To: Sebastian Andrzej Siewior Cc: Joe Perches , Adam Borowski , Michal Marek , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, ben@decadent.org.uk Subject: Re: [RFC PATCH] kbuild: add -fno-PIE References: <20161021111600.9417-1-bigeasy@linutronix.de> <20161021212127.GA32611@angband.pl> <87eg37niky.fsf@turtle.gmx.de> <1477250598.3561.4.camel@perches.com> <8760oinqly.fsf@turtle.gmx.de> <20161024074332.uomcxyhqo6aq7vxk@linutronix.de> Date: Mon, 24 Oct 2016 19:32:30 +0200 In-Reply-To: <20161024074332.uomcxyhqo6aq7vxk@linutronix.de> (Sebastian Andrzej Siewior's message of "Mon, 24 Oct 2016 09:43:32 +0200") Message-ID: <874m41mz4h.fsf@turtle.gmx.de> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) MIME-Version: 1.0 X-Provags-ID: V03:K0:8n3j64wgGIdUoc0GNkmroUUT+V1Bz0FEjrH8rnwgP9FyO8KhNh7 RpuO+7OaFZGFduSXuPqwmiC94aI50lx859OmuqN0Jmxx9Pma+Vs8G0JbDq69A9sKBfJq3Qj dHCIgWodI5mEo46reHRjLTT3ixsydjFZQqmtF0oQBiFc7JU/wMmyoGfPLd2rd+JFu7Wb1dq eK1FyX3sW6IX2dmUupxgg== X-UI-Out-Filterresults: notjunk:1; V01:K0:J/U7BtFkxZU=:NBT7mRDv1Er63UNqihzbUT SuNU43l+jmNBAgm8sGV7LU7HnvsdOfswONdlDwbRooXeci0Ybmhyn0bCHO4r3DO/6CKOcD+y+ htWgTZxOBFoW7Fr7hYdUiY3QvheMR+oaH88nHLW4VbWbUh2YXYHMX/S28dJ+vD5vZqyTAqX3i XkasPZwJWEFiOQoeSoyHjmLvwsxpcDTvLfwoxb/QDPC+W/fvU1GrEHy2Iu3W9pL/YVnBtkRsz sKq3N9l8F0f9cgIQpfyE8nCPyumKyxXQvGuXrqH6wo7vAt3LK8U8l6VZhymCi904ZXQY/fn8u PLttqOXw6kHks26DzLdz5iv1Pl2Ti01pRh77gJkSkBgdTmnbdSvCC7B5pcIOTJUCENU4zxeRv xVKUnJ7OkIq/P+KAUYSyQbHgxitBH5S1x7o3Q74sisJ5CoSBy4tlToEWF57fWTXG8Ar+z5ueD TBm/UJMSw500vVw1HGvrUky10ulao4p6+S4+NzVlm5McNZgJA1RML0FgiGvh2MrsCSwjTJAmE kbDYya77J/t2GdxsnLFqnVRh6Jjt6BzGcuD0hqqoFcUFHWaTxNtTeSyNLUkveeABOTegnkD2Z S0IccKfuEVyP5UN2MCIwpYxUrv7+/urxAQjY1gXbqE4vLQTsAOlXPypqPPQcTXWtvD1Vl/j72 4dmqiE9cvmuzB/AOQz2S6somyZbmTUGrYMa+2lRvfj572OwpZGGkHcsMLa36AMTHQBd7PgjGQ Na11qilodjjGBVexyyu7KyYr4zjE+60aGTFykxxHzyKMqBgxtGKGn9C5k+C0x8eXphhw+OL1f Rsaz320 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 2016-10-24 09:43 +0200, Sebastian Andrzej Siewior wrote: > On 2016-10-24 09:38:49 [+0200], Sven Joachim wrote: >> >> But make still fails with it. :-( > > try setting CONFIG_CC_STACKPROTECTOR_NONE=y and please let me know if > the resulting kernel built with v3.2 gcc boots & works. Sorry, I don't have gcc 3.2 around, and my gcc 3.3 environment produces assembler errors in arch/x86/entry/entry_32.S. Maybe binutils 2.15 is not recent enough anymore? Anyway, with CONFIG_CC_STACKPROTECTOR=y it is necessary to add -fno-pie in scripts/gcc-x86_64-has-stack-protector.sh as well, because that script invokes the compiler without KBUILD_CFLAGS. That's probably not a problem since -fstack-protector is newer than -fno-pie. The attached patch works for me with Debian's gcc-6 package. Cheers, Sven From 2c72542688476168920c027cdc28c6764387ecac Mon Sep 17 00:00:00 2001 From: Sven Joachim Date: Mon, 24 Oct 2016 18:17:26 +0200 Subject: [PATCH] kbuild: add -fno-pie to KBUILD_CFLAGS If GCC is configured with --enable-default-pie, the build fails early because this default is incompatible with -mcmodel=kernel. kernel/bounds.c:1:0: error: code model kernel does not support PIC mode Avoid that by adding -fno-pie to KBUILD_CFLAGS, if supported by the compiler. This flag is also needed in the x86_64 stack-protector test script which otherwise errors out. Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong available but compiler is broken See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=841420 and https://bugs.launchpad.net/ubuntu/+source/gcc-defaults/+bug/1574982. Signed-off-by: Sven Joachim --- Makefile | 1 + scripts/gcc-x86_64-has-stack-protector.sh | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 93beca4..81ef816 100644 --- a/Makefile +++ b/Makefile @@ -619,6 +619,7 @@ ARCH_AFLAGS := ARCH_CFLAGS := include arch/$(SRCARCH)/Makefile +KBUILD_CFLAGS += $(call cc-option,-fno-pie,) KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,) KBUILD_CFLAGS += $(call cc-disable-warning,maybe-uninitialized,) KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) diff --git a/scripts/gcc-x86_64-has-stack-protector.sh b/scripts/gcc-x86_64-has-stack-protector.sh index 973e8c1..274cba1 100755 --- a/scripts/gcc-x86_64-has-stack-protector.sh +++ b/scripts/gcc-x86_64-has-stack-protector.sh @@ -1,6 +1,6 @@ #!/bin/sh -echo "int foo(void) { char X[200]; return 3; }" | $* -S -x c -c -O0 -mcmodel=kernel -fstack-protector - -o - 2> /dev/null | grep -q "%gs" +echo "int foo(void) { char X[200]; return 3; }" | $* -S -x c -c -O0 -mcmodel=kernel -fno-pie -fstack-protector - -o - 2> /dev/null | grep -q "%gs" if [ "$?" -eq "0" ] ; then echo y else -- 2.10.1