From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755549AbcEXVQa (ORCPT <rfc822;w@1wt.eu>);
	Tue, 24 May 2016 17:16:30 -0400
Received: from mail-wm0-f67.google.com ([74.125.82.67]:35582 "EHLO
	mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751497AbcEXVQZ (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 24 May 2016 17:16:25 -0400
Date: Tue, 24 May 2016 23:23:24 +0200
From: Emese Revfy <re.emese@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: "kernel-hardening@lists.openwall.com" 
	<kernel-hardening@lists.openwall.com>,
        PaX Team <pageexec@freemail.hu>,
        Brad Spengler <spender@grsecurity.net>, Michal Marek <mmarek@suse.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        linux-kbuild <linux-kbuild@vger.kernel.org>,
        "Theodore Ts'o" <tytso@mit.edu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux-MM <linux-mm@kvack.org>, Jens Axboe <axboe@kernel.dk>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        bart.vanassche@sandisk.com, "David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v1 1/3] Add the latent_entropy gcc plugin
Message-Id: <20160524232324.45fbcf77916866f30b0d6cec@gmail.com>
In-Reply-To: <CAGXu5jJHenHARDZt=51m1XbSStTxpG90Dv=Fpkn79A6pZYtGOw@mail.gmail.com>
References: <20160524001405.3e6abd1d5a63a871cc366cff@gmail.com>
	<20160524001529.0e69232eff0b1b5bc566a763@gmail.com>
	<CAGXu5jJHenHARDZt=51m1XbSStTxpG90Dv=Fpkn79A6pZYtGOw@mail.gmail.com>
X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, 24 May 2016 10:32:15 -0700
Kees Cook <keescook@chromium.org> wrote:

> Also, does this matter that it's non-atomic? It seems like the u64
> below is being written to by multiple threads and even read by
> multiple threads. Am I misunderstanding something?

The non-atomic accesses are intentional because
they can extract more latent entropy from these data races.
 
> > [...]
> > new file mode 100644
> > index 0000000..7295c39
> > --- /dev/null
> > +++ b/scripts/gcc-plugins/latent_entropy_plugin.c
> 
> I feel like most of the functions in this plugin could use some more
> comments about what each one does.

I think the important parts are commented (most parts just use the gcc API).
Where would you like more comments?

-- 
Emese