From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3s3TM22dzYzDrJT for ; Tue, 2 Aug 2016 18:07:10 +1000 (AEST) 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) List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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