* [PATCH] powerpc/32: fix csum_partial_copy_generic()
@ 2016-08-01 12:56 Christophe Leroy
2016-08-01 13:15 ` Segher Boessenkool
0 siblings, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2016-08-01 12:56 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Scott Wood
Cc: linux-kernel, linuxppc-dev, stable, antoine.blangy
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
Fixes: 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic()
based on copy_tofrom_user()")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/lib/checksum_32.S | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index d90870a..ad0870a 100644
--- 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
--
2.1.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] powerpc/32: fix csum_partial_copy_generic()
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
0 siblings, 1 reply; 4+ messages in thread
From: Segher Boessenkool @ 2016-08-01 13:15 UTC (permalink / raw)
To: Christophe Leroy
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Scott Wood, antoine.blangy, linuxppc-dev, linux-kernel, stable
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/32: fix csum_partial_copy_generic()
2016-08-01 13:15 ` Segher Boessenkool
@ 2016-08-01 13:45 ` Christophe Leroy
2016-08-01 14:31 ` Segher Boessenkool
0 siblings, 1 reply; 4+ messages in thread
From: Christophe Leroy @ 2016-08-01 13:45 UTC (permalink / raw)
To: Segher Boessenkool
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Scott Wood, antoine.blangy, linuxppc-dev, linux-kernel, stable
Le 01/08/2016 à 15:15, Segher Boessenkool a écrit :
> 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.
>
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) ?
Christophe
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] powerpc/32: fix csum_partial_copy_generic()
2016-08-01 13:45 ` Christophe Leroy
@ 2016-08-01 14:31 ` Segher Boessenkool
0 siblings, 0 replies; 4+ messages in thread
From: Segher Boessenkool @ 2016-08-01 14:31 UTC (permalink / raw)
To: Christophe Leroy
Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman,
Scott Wood, antoine.blangy, linuxppc-dev, linux-kernel, stable
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
^ permalink raw reply [flat|nested] 4+ messages in thread
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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
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