Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932345AbdLOJxD (ORCPT ); Fri, 15 Dec 2017 04:53:03 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:35952 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932311AbdLOJw4 (ORCPT ); Fri, 15 Dec 2017 04:52:56 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Paul Mackerras , Michael Ellerman Subject: [PATCH 4.9 22/27] powerpc/64: Fix checksum folding in csum_tcpudp_nofold and ip_fast_csum_nofold Date: Fri, 15 Dec 2017 10:52:05 +0100 Message-Id: <20171215092259.054944522@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171215092257.674368056@linuxfoundation.org> References: <20171215092257.674368056@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1995 Lines: 68 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Mackerras commit b492f7e4e07a28e706db26cf4943bb0911435426 upstream. These functions compute an IP checksum by computing a 64-bit sum and folding it to 32 bits (the "nofold" in their names refers to folding down to 16 bits). However, doing (u32) (s + (s >> 32)) is not sufficient to fold a 64-bit sum to 32 bits correctly. The addition can produce a carry out from bit 31, which needs to be added in to the sum to produce the correct result. To fix this, we copy the from64to32() function from lib/checksum.c and use that. Signed-off-by: Paul Mackerras Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/include/asm/checksum.h | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) --- a/arch/powerpc/include/asm/checksum.h +++ b/arch/powerpc/include/asm/checksum.h @@ -53,17 +53,25 @@ static inline __sum16 csum_fold(__wsum s return (__force __sum16)(~((__force u32)sum + tmp) >> 16); } +static inline u32 from64to32(u64 x) +{ + /* add up 32-bit and 32-bit for 32+c bit */ + x = (x & 0xffffffff) + (x >> 32); + /* add up carry.. */ + x = (x & 0xffffffff) + (x >> 32); + return (u32)x; +} + static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len, __u8 proto, __wsum sum) { #ifdef __powerpc64__ - unsigned long s = (__force u32)sum; + u64 s = (__force u32)sum; s += (__force u32)saddr; s += (__force u32)daddr; s += proto + len; - s += (s >> 32); - return (__force __wsum) s; + return (__force __wsum) from64to32(s); #else __asm__("\n\ addc %0,%0,%1 \n\ @@ -123,8 +131,7 @@ static inline __wsum ip_fast_csum_nofold for (i = 0; i < ihl - 1; i++, ptr++) s += *ptr; - s += (s >> 32); - return (__force __wsum)s; + return (__force __wsum)from64to32(s); #else __wsum sum, tmp;