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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 887BCC433E0 for ; Wed, 27 May 2020 13:54:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6ADC62078C for ; Wed, 27 May 2020 13:54:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388623AbgE0NyM (ORCPT ); Wed, 27 May 2020 09:54:12 -0400 Received: from mout.kundenserver.de ([212.227.126.134]:50787 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387581AbgE0NyM (ORCPT ); Wed, 27 May 2020 09:54:12 -0400 Received: from threadripper.lan ([149.172.98.151]) by mrelayeu.kundenserver.de (mreue009 [212.227.15.129]) with ESMTPA (Nemesis) id 1MJm8H-1jKMLM2LCT-00K8Nw; Wed, 27 May 2020 15:53:33 +0200 From: Arnd Bergmann To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org Cc: Arnd Bergmann , "H. Peter Anvin" , "Kirill A. Shutemov" , Zhenzhong Duan , Kees Cook , Peter Zijlstra , Juergen Gross , Andy Lutomirski , Andrew Cooper , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH] x86: work around clang IAS bug referencing __force_order Date: Wed, 27 May 2020 15:53:19 +0200 Message-Id: <20200527135329.1172644-1-arnd@arndb.de> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:lPqKd3ceKcOiWSf6k7n0RT4DN5BdzpvV9e/sXSasbhanLS+Oa8b zCfaDCYQCGPRsqQGnAq8IlMVatLfXkTtRhm+oZ9caPDHrTJjA28xSHP6uw7B7cbHoP+DUp2 OtVtwLD2cSC0Lh2zT2hmfjFQZ7KcflKRXk++pbClkDFjbyAGo09nwQMeJLEUflpWaeQhwzs kFb0rHfkf/bj8PjONn4ZQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:fwuCPC7PnkQ=:DL0TsWJH75aNmoZSVF1D5Q dq+b71QtO2Ax/M1aqBhd8xXm/oHYJdSt+YMBPcX83mfCr3VKdX5B7t9SdQzzpVF6bzcFm1vvv qUmO1MTs/90Szakgatu6YNZi8D6fOeo8QrbRNeVLjT2GJwa+rR7wi/8bkJaV7lF/uZ604GfIt o43mOSlA2z4VHItLnYb4nvlIAPc6DiwgMM91rue4RK6IUpnGDY7PToLoIF+X+Zc5eCxI0NT2I cmzeKREiMZEVWhXvxP5XamgDv6/3EaMiUBrEiy+hq+Q2a0PwTAeTq4KE+ld/181RunLOj8j4R /aOFL8r8p5TCEA6TwIaye45ypXXoEdR+YKXWTnj1D6c4+yW0zSbxbQiFfBoKtXeBm6Z8FTJEc d2lrSiJGzLuaD2rF/IZkkxj6bcsDTNz0IsAo3JctqfHRE/xhd+x6cCMAd+RxVBI2p+WdkDSSI A45dSQJ+inGZEZR++eOdnQyfAR1FRJQh1ex89aTswZXLnO21jOCrTncn9fRMRMewwGXsBU1Nv 9urovaD3b5NuSMJ0jUBkmRF7oXzkdPDYjKdexKMFgaxVecf4HEg0jvbnZhF/3atzYv5XI+2jo OcLGlSReK1DTRpoVYn1X2kLCBptbJpXqZ4UMoTjw5y5rkZXaGo+qZCEHnUMouIXvjPReWtY/W oLNFN1ic2RsCD4tTxmlbG0e2z6Nv8bvtWlvJ5PEwxLHzmQr6cjNyxHx7eMZvAvBPHq/88y5eU pu/PPoXunnSctZWlfOvL6pDkVcJUPl6lTK24QuvoItc1tYZ9HOO92obr2kVBIIHTfefxQWp0M ri9ItI+AQjsep3e55X17LZfWUAp0pDioitA40fBjN3LHpZo0Uw= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When using the clang integrated assembler, we get a reference to __force_order that should normally get ignored in a few rare cases: ERROR: modpost: "__force_order" [drivers/cpufreq/powernow-k6.ko] undefined! Add a 'static' definition so any file in which this happens can have a local copy. Signed-off-by: Arnd Bergmann --- arch/x86/boot/compressed/pgtable_64.c | 2 ++ arch/x86/include/asm/special_insns.h | 7 +++++++ 2 files changed, 9 insertions(+) diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c index c8862696a47b..8595194cea41 100644 --- a/arch/x86/boot/compressed/pgtable_64.c +++ b/arch/x86/boot/compressed/pgtable_64.c @@ -12,7 +12,9 @@ * It is not referenced from the code, but GCC < 5 with -fPIE would fail * due to an undefined symbol. Define it to make these ancient GCCs work. */ +#ifndef CONFIG_CC_IS_CLANG unsigned long __force_order; +#endif #define BIOS_START_MIN 0x20000U /* 128K, less than this is insane */ #define BIOS_START_MAX 0x9f000U /* 640K, absolute maximum */ diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h index 82436cb04ccf..7081e587c1ea 100644 --- a/arch/x86/include/asm/special_insns.h +++ b/arch/x86/include/asm/special_insns.h @@ -16,8 +16,15 @@ * A memory clobber would solve the problem, but would prevent reordering of * all loads stores around it, which can hurt performance. Solution is to * use a variable and mimic reads and writes to it to enforce serialization + * + * Clang sometimes fails to kill the reference to the dummy variable, so + * provide an actual copy. */ +#ifdef CONFIG_CC_IS_CLANG +static unsigned long __force_order; +#else extern unsigned long __force_order; +#endif void native_write_cr0(unsigned long val); -- 2.26.2