[PATCH] amd64 rt_sigframe user annotation

->pretcode in struct rt_sigframe is a userland pointer (and already
treated as such by code using that field). 
Signed-off-by: NAl Viro <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/signal.c

@@ -83,7 +83,7 @@ sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
 
 struct rt_sigframe
 {
-	char *pretcode;
+	char __user *pretcode;
 	struct ucontext uc;
 	struct siginfo info;
 };