Date: Mon, 30 Apr 2018 14:51:15 -0700
From: Kees Cook <kees@outflux.net>
Subject: [MODERATED] Re: [patch V8 13/15] SSB 13
Message-ID: <20180430215115.GG8398@outflux.net>
References: <20180430150423.180110059@linutronix.de>
 <20180430151232.853543083@linutronix.de>
MIME-Version: 1.0
In-Reply-To: <20180430151232.853543083@linutronix.de>
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
To: speck@linutronix.de

On Mon, Apr 30, 2018 at 05:04:36PM +0200, speck for Thomas Gleixner wrote:
> Subject: [patch V8 13/15] prctl: Add speculation control prctls
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> Add two new prctls to control aspects of speculation related vulnerabilites
> and their mitigations to provide finer grained control over performance
> impacting mitigations.
> 
> PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature
> which is selected with arg2 of prctl(2). The return value uses bit 0-2 with
> the following meaning:
> 
> Bit  Define           Description
> 0    PR_SPEC_PRCTL    Mitigation can be controlled per task by
>                       PR_SET_SPECULATION_CTRL
> 1    PR_SPEC_ENABLE   The speculation feature is enabled, mitigation is
>                       disabled
> 2    PR_SPEC_DISABLE  The speculation feature is disabled, mitigation is
>                       enabled

Err, what does it mean to have both bits 1 and 2 set?

-Kees

-- 
Kees Cook                                            @outflux.net