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Date: Tue, 12 May 2015 08:25:59 -0700
Message-ID: <CADyApD2-J07zg7gfa+LrFbHB_p2gN5k2P+x7OTCW1_rybTkdQA@mail.gmail.com>
Subject: Re: [PATCH v2] x86: Preserve iopl on fork and execve
From: Arjan van de Ven <arjanvandeven@gmail.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Alex Henrie <alexhenrie24@gmail.com>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Kees Cook <keescook@chromium.org>, "H . Peter Anvin" <hpa@zytor.com>,
        Doug Johnson <dougvj@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Tyler Hicks <tyhicks@canonical.com>,
        Al Viro <viro@zeniv.linux.org.uk>, LKML <linux-kernel@vger.kernel.org>,
        Andy Lutomirski <luto@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Arjan van de Ven <arjan@infradead.org>,
        Denys Vlasenko <dvlasenk@redhat.com>, Brian Gerst <brgerst@gmail.com>
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>
> also the interesting question is:
> can a process give up these perms?
> otherwise it becomes a "once given, never gotten rid of" hell hole.

If you look at a modern linux distro, nothing should need/use iopl and
co anymore, so maybe an interesting
question is if we can stick these behind a CONFIG_ option (default on
of course for compatibility)... just like
some of the /dev/mem like things are now hidable for folks who know
they don't need them.
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