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: 4+ 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 14:31 ` Segher Boessenkool [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160801143103.GB1742@gate.crashing.org \
--to=segher@kernel.crashing.org \
--cc=antoine.blangy@c-s.fr \
--cc=benh@kernel.crashing.org \
--cc=christophe.leroy@c-s.fr \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=oss@buserror.net \
--cc=paulus@samba.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).