From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932670AbcHBLvm (ORCPT ); Tue, 2 Aug 2016 07:51:42 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:51846 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755109AbcHBLve (ORCPT ); Tue, 2 Aug 2016 07:51:34 -0400 From: Christophe Leroy Subject: [PATCH v2] powerpc/32: fix csum_partial_copy_generic() To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Scott Wood Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, stable@vger.kernel.org, antoine.blangy@c-s.fr, segher@kernel.crashing.org Message-Id: <20160802080705.69A9F1A2394@localhost.localdomain> Date: Tue, 2 Aug 2016 10:07:05 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic() based on copy_tofrom_user()") introduced a bug when destination address is odd and initial csum is not null In that (rare) case the initial csum value has to be rotated one byte as well as the resulting value is This patch also fixes related comments Fixes: 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic() based on copy_tofrom_user()") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy --- v2: updated comments as suggested by Segher arch/powerpc/lib/checksum_32.S | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S index d90870a..0a57fe6 100644 --- a/arch/powerpc/lib/checksum_32.S +++ b/arch/powerpc/lib/checksum_32.S @@ -127,8 +127,9 @@ _GLOBAL(csum_partial_copy_generic) stw r7,12(r1) stw r8,8(r1) - andi. r0,r4,1 /* is destination address even ? */ - cmplwi cr7,r0,0 + rlwinm r0,r4,3,0x8 + rlwnm r6,r6,r0,0,31 /* odd destination address: rotate one byte */ + cmplwi cr7,r0,0 /* is destination address even ? */ addic r12,r6,0 addi r6,r4,-4 neg r0,r4 @@ -237,7 +238,7 @@ _GLOBAL(csum_partial_copy_generic) 66: addze r3,r12 addi r1,r1,16 beqlr+ cr7 - rlwinm r3,r3,8,0,31 /* swap bytes for odd destination */ + rlwinm r3,r3,8,0,31 /* odd destination address: rotate one byte */ blr /* read fault */ -- 2.1.0