[RFC PATCH] uprobes: copy to user-space xol page with proper cache flushing

[David Miller]

From: Oleg Nesterov <oleg at redhat.com>
Date: Tue, 15 Apr 2014 19:43:30 +0200

> Finally, let me repeat, you should verify that this
> __copy_to_user_page(page, uaddr, kaddr) will not something bad if uaddr
> is not mmapped, or its mapping do not match area->page.

Just directly access userspace with the usual exception mechanism we
use for copy_to_user(), put_user(), et al. and if it faults you'll get
-EFAULT and handle it.

This also avoids the D-cache aliasing issues entirely as I explained
in my other reply.