From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 03 Sep 2018 19:39:29 +0200 (CEST) Received: from mail.linuxfoundation.org ([140.211.169.12]:39544 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23993976AbeICRiqgJuSO (ORCPT ); Mon, 3 Sep 2018 19:38:46 +0200 Received: from localhost (ip-213-127-74-90.ip.prioritytelecom.net [213.127.74.90]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 308EDBC4; Mon, 3 Sep 2018 17:38:40 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paul Burton , Vladimir Kondratiev , James Hogan , Ralf Baechle , linux-mips@linux-mips.org Subject: [PATCH 4.18 103/123] MIPS: lib: Provide MIPS64r6 __multi3() for GCC < 7 Date: Mon, 3 Sep 2018 18:57:27 +0200 Message-Id: <20180903165723.885045975@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180903165719.499675257@linuxfoundation.org> References: <20180903165719.499675257@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 65915 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: gregkh@linuxfoundation.org Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Burton commit 690d9163bf4b8563a2682e619f938e6a0443947f upstream. Some versions of GCC suboptimally generate calls to the __multi3() intrinsic for MIPS64r6 builds, resulting in link failures due to the missing function: LD vmlinux.o MODPOST vmlinux.o kernel/bpf/verifier.o: In function `kmalloc_array': include/linux/slab.h:631: undefined reference to `__multi3' fs/select.o: In function `kmalloc_array': include/linux/slab.h:631: undefined reference to `__multi3' ... We already have a workaround for this in which we provide the instrinsic, but we do so selectively for GCC 7 only. Unfortunately the issue occurs with older GCC versions too - it has been observed with both GCC 5.4.0 & GCC 6.4.0. MIPSr6 support was introduced in GCC 5, so all major GCC versions prior to GCC 8 are affected and we extend our workaround accordingly to all MIPS64r6 builds using GCC versions older than GCC 8. Signed-off-by: Paul Burton Reported-by: Vladimir Kondratiev Fixes: ebabcf17bcd7 ("MIPS: Implement __multi3 for GCC7 MIPS64r6 builds") Patchwork: https://patchwork.linux-mips.org/patch/20297/ Cc: James Hogan Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # 4.15+ Signed-off-by: Greg Kroah-Hartman --- arch/mips/lib/multi3.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/arch/mips/lib/multi3.c +++ b/arch/mips/lib/multi3.c @@ -4,12 +4,12 @@ #include "libgcc.h" /* - * GCC 7 suboptimally generates __multi3 calls for mips64r6, so for that - * specific case only we'll implement it here. + * GCC 7 & older can suboptimally generate __multi3 calls for mips64r6, so for + * that specific case only we implement that intrinsic here. * * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82981 */ -#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) && (__GNUC__ == 7) +#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) && (__GNUC__ < 8) /* multiply 64-bit values, low 64-bits returned */ static inline long long notrace dmulu(long long a, long long b)