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Date: Mon, 22 Dec 2014 12:21:35 -0800
From: Dave Hansen <dave@sr71.net>
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To: Andy Lutomirski <luto@amacapital.net>
CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH 1/2] x86, mpx: explicitly disable 32-bit MPX support on
 64-bit kernels
References: <20141222200803.D316DA2A@viggo.jf.intel.com> <20141222200804.18A7A803@viggo.jf.intel.com> <CALCETrWAgPjLTA-iSabFmqVKiOKGPGgDgSWdjz3wsncs1X+WOg@mail.gmail.com>
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On 12/22/2014 12:17 PM, Andy Lutomirski wrote:
>> >         /*
>> > +        * 32-bit binaries on 64-bit kernels are currently
>> > +        * unsupported.
>> > +        */
>> > +       if (IS_ENABLED(CONFIG_X86_64) && test_thread_flag(TIF_IA32))
>> > +               return MPX_INVALID_BOUNDS_DIR;
> Should this check mm->ia32_compat instead?

set_personality_64bit/ia32() seem to make that and TIF_IA32 awfully
equivalent.  Is there a specific reason for wanting it done this way?