new helper: restore_altstack()

to be used by rt_sigreturn instances Signed-off-by: Al Viro <[email protected]>
chewitt · Dec 19, 2012 · 5c49574 · 5c49574
1 parent 031b656
commit 5c49574
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diff --git a/include/linux/signal.h b/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/kernel/signal.c b/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
 
 /**