kernel-hardening - Re: [RFC PATCH v8 03/14] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO)

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Message-ID: <6c689028-6748-66b9-0d9c-2b57b5dd6383@oracle.com>
Date: Thu, 14 Feb 2019 10:19:23 -0700
From: Khalid Aziz <khalid.aziz@...cle.com>
To: Borislav Petkov <bp@...en8.de>, juergh@...il.com
Cc: Peter Zijlstra <peterz@...radead.org>, tycho@...ho.ws, jsteckli@...zon.de,
        ak@...ux.intel.com, torvalds@...ux-foundation.org,
        liran.alon@...cle.com, keescook@...gle.com, akpm@...ux-foundation.org,
        mhocko@...e.com, catalin.marinas@....com, will.deacon@....com,
        jmorris@...ei.org, konrad.wilk@...cle.com,
        Juerg Haefliger <juerg.haefliger@...onical.com>,
        deepa.srinivasan@...cle.com, chris.hyser@...cle.com,
        tyhicks@...onical.com, dwmw@...zon.co.uk, andrew.cooper3@...rix.com,
        jcm@...hat.com, boris.ostrovsky@...cle.com, kanth.ghatraju@...cle.com,
        joao.m.martins@...cle.com, jmattson@...gle.com,
        pradeep.vincent@...cle.com, john.haxby@...cle.com, tglx@...utronix.de,
        kirill.shutemov@...ux.intel.com, hch@....de, steven.sistare@...cle.com,
        labbott@...hat.com, luto@...nel.org, dave.hansen@...el.com,
        kernel-hardening@...ts.openwall.com, linux-mm@...ck.org,
        x86@...nel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Marco Benatto <marco.antonio.780@...il.com>
Subject: Re: [RFC PATCH v8 03/14] mm, x86: Add support for eXclusive Page
 Frame Ownership (XPFO)

On 2/14/19 9:15 AM, Borislav Petkov wrote:
> On Thu, Feb 14, 2019 at 11:56:31AM +0100, Peter Zijlstra wrote:
>>> +EXPORT_SYMBOL(xpfo_kunmap);
>>
>> And these here things are most definitely not IRQ-safe.
> 
> Should also be EXPORT_SYMBOL_GPL.
> 

Agreed. On the other hand, is there even a need to export this? It
should only be called from kunmap() or kunmap_atomic() and not from any
module directly. Same for xpfo_kmap.

Thanks,
Khalid

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