x86/vdso: Add __user annotation to VDSO32_SYMBOL

The address calculated by VDSO32_SYMBOL() is a pointer into
userland. Add the __user annotation to fix related sparse
warnings in its users.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Andy Lutomirski <luto@MIT.EDU>
Link: http://lkml.kernel.org/r/1346621506-30857-3-git-send-email-minipli@googlemail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/vdso.h

@@ -11,7 +11,8 @@ extern const char VDSO32_PRELINK[];
 #define VDSO32_SYMBOL(base, name)					\
 ({									\
 	extern const char VDSO32_##name[];				\
-	(void *)(VDSO32_##name - VDSO32_PRELINK + (unsigned long)(base)); \
+	(void __user *)(VDSO32_##name - VDSO32_PRELINK +		\
+			(unsigned long)(base));				\
 })
 #endif