From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <segher@gate.crashing.org>
Received: from gate.crashing.org (gate.crashing.org [63.228.1.57])
 (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by lists.ozlabs.org (Postfix) with ESMTPS id 3s30GD2d33zDqQK
 for <linuxppc-dev@lists.ozlabs.org>; Mon,  1 Aug 2016 23:16:20 +1000 (AEST)
Date: Mon, 1 Aug 2016 08:15:06 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Paul Mackerras <paulus@samba.org>,
 Michael Ellerman <mpe@ellerman.id.au>, Scott Wood <oss@buserror.net>,
 antoine.blangy@c-s.fr, linuxppc-dev@lists.ozlabs.org,
 linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] powerpc/32: fix csum_partial_copy_generic()
Message-ID: <20160801131505.GA1742@gate.crashing.org>
References: <20160801125605.410371A23A2@localhost.localdomain>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
In-Reply-To: <20160801125605.410371A23A2@localhost.localdomain>
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>

On Mon, Aug 01, 2016 at 02:56:05PM +0200, Christophe Leroy wrote:
> --- a/arch/powerpc/lib/checksum_32.S
> +++ b/arch/powerpc/lib/checksum_32.S
> @@ -127,7 +127,8 @@ _GLOBAL(csum_partial_copy_generic)
>  	stw	r7,12(r1)
>  	stw	r8,8(r1)
>  
> -	andi.	r0,r4,1			/* is destination address even ? */
> +	rlwinm	r0,r4,3,0x8		/* is destination address even ? */
> +	rlwnm	r6,r6,r0,0,31		/* swap bytes for odd destination */
>  	cmplwi	cr7,r0,0
>  	addic	r12,r6,0
>  	addi	r6,r4,-4

That does not "swap bytes"; it shifts the word up by 8 bits, instead.
That may or may not do what is intended.


Segher