[3.13.y-ckt stable] Patch "xtensa: fix threadptr reload on return to userspace" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    xtensa: fix threadptr reload on return to userspace

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt28.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From ac0d654295587fc4a74da06268c60836d973908e Mon Sep 17 00:00:00 2001
From: Max Filippov <jcmvbkbc at gmail.com>
Date: Sat, 4 Jul 2015 15:27:39 +0300
Subject: xtensa: fix threadptr reload on return to userspace

commit 4229fb12a03e5da5882b420b0aa4a02e77447b86 upstream.

Userspace return code may skip restoring THREADPTR register if there are
no registers that need to be zeroed. This leads to spurious failures in
libc NPTL tests.

Always restore THREADPTR on return to userspace.

Signed-off-by: Max Filippov <jcmvbkbc at gmail.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/xtensa/kernel/entry.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 4b8e636..900137e 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -568,12 +568,13 @@ user_exception_exit:
 	 *	 (if we have restored WSBITS-1 frames).
 	 */

+2:
 #if XCHAL_HAVE_THREADPTR
 	l32i	a3, a1, PT_THREADPTR
 	wur	a3, threadptr
 #endif

-2:	j	common_exception_exit
+	j	common_exception_exit

 	/* This is the kernel exception exit.
 	 * We avoided to do a MOVSP when we entered the exception, but we
--
1.9.1