linux-kernel - [PATCH 3.19.y-ckt 009/156] xtensa: fix threadptr reload on return to userspace

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Message-Id: <1445377097-9921-10-git-send-email-kamal@canonical.com>
Date:	Tue, 20 Oct 2015 14:35:50 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Max Filippov <jcmvbkbc@...il.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 009/156] xtensa: fix threadptr reload on return to userspace

3.19.8-ckt8 -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: Kamal Mostafa <kamal@...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 82bbfa5..51e9877 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

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