linux-kernel - [PATCH 3.16.y-ckt 007/133] xtensa: fix threadptr reload on return to userspace

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Message-Id: <1443606681-7124-8-git-send-email-luis.henriques@canonical.com>
Date:	Wed, 30 Sep 2015 10:49:15 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Max Filippov <jcmvbkbc@...il.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 007/133] xtensa: fix threadptr reload on return to userspace

3.16.7-ckt18 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Max Filippov <jcmvbkbc@...il.com>

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@...il.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.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 a06b7efaae82..8a749f02d8d6 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
--
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