diff --git a/[refs] b/[refs]
index fd6a12e93e50..43d49752e874 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 031b6566983ad9c0247087f039af22b3f87596a3
+refs/heads/master: 5c49574ffd7ac07eae8c3b065d19e6ebc7e4760f
diff --git a/trunk/include/linux/signal.h b/trunk/include/linux/signal.h
index e19a011b43b7..5969522136fe 100644
--- a/trunk/include/linux/signal.h
+++ b/trunk/include/linux/signal.h
@@ -385,4 +385,6 @@ int unhandled_signal(struct task_struct *tsk, int sig);
 
 void signals_init(void);
 
+int restore_altstack(const stack_t __user *);
+
 #endif /* _LINUX_SIGNAL_H */
diff --git a/trunk/kernel/signal.c b/trunk/kernel/signal.c
index e75e4bd2839b..887f2fefe207 100644
--- a/trunk/kernel/signal.c
+++ b/trunk/kernel/signal.c
@@ -3103,6 +3103,13 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
 	return error;
 }
 
+int restore_altstack(const stack_t __user *uss)
+{
+	int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
+	/* squash all but EFAULT for now */
+	return err == -EFAULT ? err : 0;
+}
+
 #ifdef __ARCH_WANT_SYS_SIGPENDING
 
 /**