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

From: [email-masked] (Oleg Nesterov)
Date: Tue, 15 Apr 2014 20:03:11 +0200

On 04/15, David Miller wrote:
>
> From: Oleg Nesterov <[email-masked]>
> 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.

Yes, yes, this is obvious.

But I have no idea what else we should do to take care of icache.

Oleg.