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()
Date: Mon, 1 Aug 2016 09:31:04 -0500 [thread overview]
Message-ID: <20160801143103.GB1742@gate.crashing.org> (raw)
In-Reply-To: <cf1cb854-053b-a468-f683-dc752f3fda35@c-s.fr>
On Mon, Aug 01, 2016 at 03:45:59PM +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.
>
> Indeed it does what is intended, similar to what is done at the end of
> the function:
>
> ...
> beqlr+ cr7
> rlwinm r3,r3,8,0,31 /* swap bytes for odd destination */
> blr
>
> Should I fix the (both) comment(s) ?
It's quite confusing comment, so yes please. The code is hard enough to
understand as is!
Segher
prev parent reply other threads:[~2016-08-01 14:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 12:56 [PATCH] powerpc/32: fix csum_partial_copy_generic() Christophe Leroy
2016-08-01 13:15 ` Segher Boessenkool
2016-08-01 13:45 ` Christophe Leroy
2016-08-01 13:45 ` Christophe Leroy
2016-08-01 14:31 ` Segher Boessenkool [this message]
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