[tip:x86/mpx] x86: replace futex_atomic_cmpxchg_inatomic() with user_atomic_cmpxchg_inatomic

[tip-bot for Qiaowei Ren <tipbot@zytor.com>]

Commit-ID:  0ee3b6f87d4d748d5362cb47ff33fa1553805cb4
Gitweb:     http://git.kernel.org/tip/0ee3b6f87d4d748d5362cb47ff33fa1553805cb4
Author:     Qiaowei Ren <qiaowei.ren@intel.com>
AuthorDate: Sat, 14 Dec 2013 14:25:03 +0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Mon, 16 Dec 2013 09:08:13 -0800

x86: replace futex_atomic_cmpxchg_inatomic() with user_atomic_cmpxchg_inatomic

futex_atomic_cmpxchg_inatomic() is simply the 32-bit implementation of
user_atomic_cmpxchg_inatomic(), which in turn is simply a
generalization of the original code in
futex_atomic_cmpxchg_inatomic().

Use the newly generalized user_atomic_cmpxchg_inatomic() as the futex
implementation, too.

[ hpa: retain the inline in futex.h rather than changing it to a macro ]

Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Link: http://lkml.kernel.org/r/1387002303-6620-2-git-send-email-qiaowei.ren@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/x86/include/asm/futex.h | 21 +--------------------
 1 file changed, 1 insertion(+), 20 deletions(-)

diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h
index be27ba1..b4c1f54 100644
--- a/arch/x86/include/asm/futex.h
+++ b/arch/x86/include/asm/futex.h
@@ -110,26 +110,7 @@ static inline int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr)
 static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 						u32 oldval, u32 newval)
 {
-	int ret = 0;
-
-	if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
-		return -EFAULT;
-
-	asm volatile("\t" ASM_STAC "\n"
-		     "1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
-		     "2:\t" ASM_CLAC "\n"
-		     "\t.section .fixup, \"ax\"\n"
-		     "3:\tmov     %3, %0\n"
-		     "\tjmp     2b\n"
-		     "\t.previous\n"
-		     _ASM_EXTABLE(1b, 3b)
-		     : "+r" (ret), "=a" (oldval), "+m" (*uaddr)
-		     : "i" (-EFAULT), "r" (newval), "1" (oldval)
-		     : "memory"
-	);
-
-	*uval = oldval;
-	return ret;
+	return user_atomic_cmpxchg_inatomic(uval, uaddr, oldval, newval);
 }
 
 #endif