FAILED: patch "[PATCH] parisc: Fix double-word compare and exchange in LWS code on" failed to apply to 3.18-stable tree

FAILED: patch "[PATCH] parisc: Fix double-word compare and exchange in LWS code on" failed to apply to 3.18-stable tree

[gregkh]

The patch below does not apply to the 3.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 374b3bf8e8b519f61eb9775888074c6e46b3bf0c Mon Sep 17 00:00:00 2001
From: John David Anglin <dave.anglin@bell.net>
Date: Sat, 30 Sep 2017 17:24:23 -0400
Subject: [PATCH] parisc: Fix double-word compare and exchange in LWS code on
 32-bit kernels

As discussed on the debian-hppa list, double-wordcompare and exchange
operations fail on 32-bit kernels.  Looking at the code, I realized that
the ",ma" completer does the wrong thing in the  "ldw,ma  4(%r26), %r29"
instruction.  This increments %r26 and causes the following store to
write to the wrong location.

Note by Helge Deller:
The patch applies cleanly to stable kernel series if this upstream
commit is merged in advance:
f4125cfdb300 ("parisc: Avoid trashing sr2 and sr3 in LWS code").

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Tested-by: Christoph Biedl <debian.axhn@manchmal.in-ulm.de>
Fixes: 89206491201c ("parisc: Implement new LWS CAS supporting 64 bit operations.")
Cc: stable@vger.kernel.org # 3.13+
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 23de307c3052..41e60a9c7db2 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -742,7 +742,7 @@ lws_compare_and_swap_2:
 10:	ldd	0(%r25), %r25
 11:	ldd	0(%r24), %r24
 #else
-	/* Load new value into r22/r23 - high/low */
+	/* Load old value into r22/r23 - high/low */
 10:	ldw	0(%r25), %r22
 11:	ldw	4(%r25), %r23
 	/* Load new value into fr4 for atomic store later */
@@ -834,11 +834,11 @@ cas2_action:
 	copy	%r0, %r28
 #else
 	/* Compare first word */
-19:	ldw,ma	0(%r26), %r29
+19:	ldw	0(%r26), %r29
 	sub,=	%r29, %r22, %r0
 	b,n	cas2_end
 	/* Compare second word */
-20:	ldw,ma	4(%r26), %r29
+20:	ldw	4(%r26), %r29
 	sub,=	%r29, %r23, %r0
 	b,n	cas2_end
 	/* Perform the store */

Re: FAILED: patch "[PATCH] parisc: Fix double-word compare and exchange in LWS code on" failed to apply to 3.18-stable tree

[Helge Deller]

Hi Greg,

On 23.10.2017 14:47, gregkh@linuxfoundation.org wrote:
> The patch below does not apply to the 3.18-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Please pull in this trivial commit first:
  f4125cfdb300 ("parisc: Avoid trashing sr2 and sr3 in LWS code").

Then this patch here applies cleanly.

Thanks,
Helge


> 
> thanks,
> 
> greg k-h
> 
> ------------------ original commit in Linus's tree ------------------
> 
>  From 374b3bf8e8b519f61eb9775888074c6e46b3bf0c Mon Sep 17 00:00:00 2001
> From: John David Anglin <dave.anglin@bell.net>
> Date: Sat, 30 Sep 2017 17:24:23 -0400
> Subject: [PATCH] parisc: Fix double-word compare and exchange in LWS code on
>   32-bit kernels
> 
> As discussed on the debian-hppa list, double-wordcompare and exchange
> operations fail on 32-bit kernels.  Looking at the code, I realized that
> the ",ma" completer does the wrong thing in the  "ldw,ma  4(%r26), %r29"
> instruction.  This increments %r26 and causes the following store to
> write to the wrong location.
> 
> Note by Helge Deller:
> The patch applies cleanly to stable kernel series if this upstream
> commit is merged in advance:
> f4125cfdb300 ("parisc: Avoid trashing sr2 and sr3 in LWS code").
> 
> Signed-off-by: John David Anglin <dave.anglin@bell.net>
> Tested-by: Christoph Biedl <debian.axhn@manchmal.in-ulm.de>
> Fixes: 89206491201c ("parisc: Implement new LWS CAS supporting 64 bit operations.")
> Cc: stable@vger.kernel.org # 3.13+
> Signed-off-by: Helge Deller <deller@gmx.de>
> 
> diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
> index 23de307c3052..41e60a9c7db2 100644
> --- a/arch/parisc/kernel/syscall.S
> +++ b/arch/parisc/kernel/syscall.S
> @@ -742,7 +742,7 @@ lws_compare_and_swap_2:
>   10:	ldd	0(%r25), %r25
>   11:	ldd	0(%r24), %r24
>   #else
> -	/* Load new value into r22/r23 - high/low */
> +	/* Load old value into r22/r23 - high/low */
>   10:	ldw	0(%r25), %r22
>   11:	ldw	4(%r25), %r23
>   	/* Load new value into fr4 for atomic store later */
> @@ -834,11 +834,11 @@ cas2_action:
>   	copy	%r0, %r28
>   #else
>   	/* Compare first word */
> -19:	ldw,ma	0(%r26), %r29
> +19:	ldw	0(%r26), %r29
>   	sub,=	%r29, %r22, %r0
>   	b,n	cas2_end
>   	/* Compare second word */
> -20:	ldw,ma	4(%r26), %r29
> +20:	ldw	4(%r26), %r29
>   	sub,=	%r29, %r23, %r0
>   	b,n	cas2_end
>   	/* Perform the store */
> 

Re: FAILED: patch "[PATCH] parisc: Fix double-word compare and exchange in LWS code on" failed to apply to 3.18-stable tree

[Greg KH]

On Mon, Oct 23, 2017 at 07:45:58PM +0200, Helge Deller wrote:
> Hi Greg,
> 
> On 23.10.2017 14:47, gregkh@linuxfoundation.org wrote:
> > The patch below does not apply to the 3.18-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> 
> Please pull in this trivial commit first:
>  f4125cfdb300 ("parisc: Avoid trashing sr2 and sr3 in LWS code").
> 
> Then this patch here applies cleanly.

Ah, thanks, now done for 4.4 as well.

greg k-h