MIME-Version: 1.0
In-Reply-To: <CALCETrUGEwZAL8oO8956z9CY_CLg1Bt07KnU-7WhjukK6H0dXg@mail.gmail.com>
References: <CALCETrVw2V+Ny7=D=_E2m0Qa_v7Bp8GUjhyDXx_bWC35R2ohjg@mail.gmail.com>
	<56736BD1.5080700@linux.intel.com>
	<CALCETrWBjvTiVBPc098cGSH2vdezvdg-i6N4kZjgdcPT7uXoiQ@mail.gmail.com>
	<5673750B.606@linux.intel.com>
	<CALCETrWMofAX8TbZNyPaCWUHqcE85wpehDR05irEPtTYiVMXRA@mail.gmail.com>
	<FEA53E3B-6AE2-4305-82B1-C57451B6E33E@zytor.com>
	<CALCETrU28FoOwR+n8U0Qtt20=ZW6rgc3=M8X4G0QMt1_ZVHY7Q@mail.gmail.com>
	<567453AF.5060808@linux.intel.com>
	<CALCETrU7TnbLSzOuGNmh=xDpa5W729RJSPdap2izXxagfg-biQ@mail.gmail.com>
	<56746774.8000707@linux.intel.com>
	<CA+55aFycMWxCVY1p8n_D8nGz7Ky35uAmZMWm=zE5LBsqModiBg@mail.gmail.com>
	<CALCETrVWgFPTap_DNzP5vnrtyr7jjMwFHyRy=iY0amHrQ_euwg@mail.gmail.com>
	<CA+55aFz9XdUP0BQXuq7UuZT1ke-+JVThs-bssMi2sV2xLubHVg@mail.gmail.com>
	<567476CC.8080805@linux.intel.com>
	<CA+55aFyVJF48-QwZBD++1u8CB7EYrO1rMnwsZFW4rTBFoNXSZw@mail.gmail.com>
	<CALCETrVj51q3=AkP2PGFOKPqv0CxukbUEhvv0n6+XT+OngJK2Q@mail.gmail.com>
	<CA+55aFwU7cjSTB3Yk7S1Bcfo244WS9cm==WXZZcN3ZAs+J2jug@mail.gmail.com>
	<CALCETrUGEwZAL8oO8956z9CY_CLg1Bt07KnU-7WhjukK6H0dXg@mail.gmail.com>
Date: Fri, 18 Dec 2015 15:20:18 -0800
Message-ID: <CA+55aFxLUqiT2o6G-eSaGz1=o765U78Sxvrpx+5Y1Fk=Siei=Q@mail.gmail.com>
Subject: Re: Rethinking sigcontext's xfeatures slightly for PKRU's benefit?
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Oleg Nesterov <oleg@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>,
        Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1015
Lines: 20

On Fri, Dec 18, 2015 at 3:16 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>
> Yes, I think.  If I'm using protection keys to protect some critical
> data structure (important stuff in shared memory, important memory
> mapped files, pmem, etc), then I'll allocate a protection key and set
> PKRU to deny writes.  The problem is that I really, really want writes
> denied except when explicitly enabled in narrow regions of code that
> use wrpkru to enable them, and I don't want an asynchronous signal
> delivered in those narrow regions of code or newly cloned threads to
> pick up the write-allow value.  So I want baseline_pkru to have the
> deny writes entry.

Hmm. Ok, that does sound like a valid and interesting usage case. Fair enough.

                Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/