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-rw-r--r--include/asm-i386/futex.h27
1 files changed, 27 insertions, 0 deletions
diff --git a/include/asm-i386/futex.h b/include/asm-i386/futex.h
index 44b9db80647..7b8ceefd010 100644
--- a/include/asm-i386/futex.h
+++ b/include/asm-i386/futex.h
@@ -104,5 +104,32 @@ futex_atomic_op_inuser (int encoded_op, int __user *uaddr)
return ret;
}
+static inline int
+futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
+{
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(int)))
+ return -EFAULT;
+
+ __asm__ __volatile__(
+ "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n"
+
+ "2: .section .fixup, \"ax\" \n"
+ "3: mov %2, %0 \n"
+ " jmp 2b \n"
+ " .previous \n"
+
+ " .section __ex_table, \"a\" \n"
+ " .align 8 \n"
+ " .long 1b,3b \n"
+ " .previous \n"
+
+ : "=a" (oldval), "=m" (*uaddr)
+ : "i" (-EFAULT), "r" (newval), "0" (oldval)
+ : "memory"
+ );
+
+ return oldval;
+}
+
#endif
#endif