Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751806AbaKFJzQ (ORCPT ); Thu, 6 Nov 2014 04:55:16 -0500 Received: from mx07-00178001.pphosted.com ([62.209.51.94]:34298 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751054AbaKFJzM (ORCPT ); Thu, 6 Nov 2014 04:55:12 -0500 From: Maxime COQUELIN To: linux@rasmusvillemoes.dk, gong.chen@linux.intel.com, Peter Zijlstra , Ingo Molnar , " Paul E. McKenney" , tytso@mit.edu, linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: kernel@stlinux.com, maxime.coquelin@st.com, eric.paire@st.com Subject: [PATCH v4] bitops: Fix shift overflow in GENMASK macros Date: Thu, 6 Nov 2014 10:54:19 +0100 Message-Id: <1415267659-10563-1-git-send-email-maxime.coquelin@st.com> X-Mailer: git-send-email 1.9.1 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.12.52,1.0.28,0.0.0000 definitions=2014-11-06_04:2014-11-05,2014-11-06,1970-01-01 signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On some 32 bits architectures, including x86, GENMASK(31, 0) returns 0 instead of the expected ~0UL. This is the same on some 64 bits architectures with GENMASK_ULL(63, 0). This is due to an overflow in the shift operand, 1 << 32 for GENMASK, 1 << 64 for GENMASK_ULL. Fixes: 10ef6b0dffe404bcc54e94cb2ca1a5b18445a66b Cc: #v3.13+ Reported-by: Eric Paire Suggested-by: Rasmus Villemoes Signed-off-by: Maxime Coquelin --- include/linux/bitops.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/include/linux/bitops.h b/include/linux/bitops.h index be5fd38..5d858e0 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -18,8 +18,11 @@ * position @h. For example * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000. */ -#define GENMASK(h, l) (((U32_C(1) << ((h) - (l) + 1)) - 1) << (l)) -#define GENMASK_ULL(h, l) (((U64_C(1) << ((h) - (l) + 1)) - 1) << (l)) +#define GENMASK(h, l) \ + (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h)))) + +#define GENMASK_ULL(h, l) \ + (((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h)))) extern unsigned int __sw_hweight8(unsigned int w); extern unsigned int __sw_hweight16(unsigned int w); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/