linux-kernel - Re: [PATCH v1 1/3] Add the latent

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Message-Id: <20160524232324.45fbcf77916866f30b0d6cec@gmail.com>
Date:	Tue, 24 May 2016 23:23:24 +0200
From:	Emese Revfy <re.emese@...il.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>,
	PaX Team <pageexec@...email.hu>,
	Brad Spengler <spender@...ecurity.net>,
	Michal Marek <mmarek@...e.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Masahiro Yamada <yamada.masahiro@...ionext.com>,
	linux-kbuild <linux-kbuild@...r.kernel.org>,
	"Theodore Ts'o" <tytso@....edu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux-MM <linux-mm@...ck.org>, Jens Axboe <axboe@...nel.dk>,
	Al Viro <viro@...iv.linux.org.uk>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	bart.vanassche@...disk.com, "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v1 1/3] Add the latent_entropy gcc plugin

On Tue, 24 May 2016 10:32:15 -0700
Kees Cook <keescook@...omium.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