linux-kernel - Re: [PATCH 3.19 3/3] x86, mpx: Change the MPX enable/disable API to arch

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Date:	Tue, 6 Jan 2015 10:41:44 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Dave Hansen <dave.hansen@...ux.intel.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	X86 ML <x86@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
	ilya.enkovich@...el.com
Subject: Re: [PATCH 3.19 3/3] x86, mpx: Change the MPX enable/disable API to arch_prctl

On Tue, Jan 6, 2015 at 10:30 AM, Dave Hansen
<dave.hansen@...ux.intel.com> wrote:
> On 01/06/2015 10:06 AM, Andy Lutomirski wrote:
>> On Tue, Jan 6, 2015 at 9:48 AM, Dave Hansen <dave.hansen@...ux.intel.com> wrote:
>>> On 01/05/2015 09:59 PM, Andy Lutomirski wrote:
>>>> But I decided to check whether libmpx links against glibc, and I can't
>>>> find sources for it at all.  Do they exist?  Is there any code with
>>>> source available that invokes this prctl?
>>>>
>>>> If not, I personally have very little sympathy for the argument that a
>>>> binary buried in the depths of the Intel SDE would need to change if
>>>> we switched to using arch_prctl.  And I think that it should issue the
>>>> syscall itself without using glibc, in which case the syscall wrapper
>>>> issue is moot.
>>>
>>> Andy, as I mentioned previously, there is code in a GCC branch that uses
>>> the existing prctl().  It's also been posted for review to one of the
>>> GCC mailing lists.  I've been told that it will be in gcc 5.0.
>>
>> Can you point me to it?  I found the code generation stuff in the gcc
>> branch, but I couldn't find the runtime.
>
> cc'ing Ilya who is working on the gcc parts...
>
> Ilya, is the MPX runtime that uses the prctl() calls available somewhere
> publicly that it can be grabbed?
>
> I couldn't find it in GCC SVN anywhere.
>
>>> The Intel SDE does not use the prctl() in any way that I know of.
>>
>> I found a couple references suggesting that libmpx lived in the SDE.
>> For example:
>>
>> https://software.intel.com/en-us/articles/using-intel-mpx-with-the-intel-software-development-emulator
>
> Andy, I think you're mistaken.  The SDE allows you to run MPX code on a
> system without MPX support in hardware.  It does not, itself, provide
> MPX code.  The references you see there are to a runtime library that
> you obtain separately from the SDE.  You run the library _under_ the SDE.
>

I misread this:

There are two shared objects in the runtime kit available on the SDE page.

The runtime seems to be here:

https://software.intel.com/protected-download/267266/144917

but I'm not going to accept the EULA.

--Andy
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