[Info-vax] Alpha and no-execute, was: Re: An old VMS vulnerability, was: Re: Calling standards, was: Re:

[Simon Clubley]

On 2016-11-29, Simon Clubley <clubley at remove_me.eisner.decus.org-Earth.UFP> wrote:
> On 2016-11-29, Bob Koehler <koehler at eisner.nospam.decuserve.org> wrote:
>>
>>    No-execute is a problem, since VMS still runs on VAXen and Alphas
>>    that don't enforce no-execute.  IIRC IA64 does support it.  Don't
>>    know about x86, but I thought current generations do.
>>
>
> Did early versions of the Alpha architecture not support no-execute ?
>
> Somehow, I had thought it was available on all versions of the Alpha
> architecture.
>

I've just checked the paper version of the Alpha Architecture Reference
Manual, EY-L520E-DP, Copyright (c) 1992 in case I missed something.

On page 3-4 of OpenVMS Alpha Software (II), the PTE definition in
Table 3-2 makes it clear that bit 3, Fault On Execute (FOE), is
available.

Was this not actually implemented on some early Alpha CPUs ?

Thanks,

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world