From: Xavier Leroy <xavier.leroy@college-de-france.fr>
To: Hendrik Boom <hendrik@topoi.pooq.com>
Cc: caml users <caml-list@inria.fr>
Subject: Re: [Caml-list] Any plans for supporting Intel CET in OCaml?
Date: Wed, 31 Jul 2019 17:21:08 +0200 [thread overview]
Message-ID: <CAH=h3gG+WyBq2bMb5hzkmOFNF0ibBy2iSg4tqVn8oBRD4cLT=w@mail.gmail.com> (raw)
In-Reply-To: <20190731141952.zod7aftusgchoiyq@topoi.pooq.com>
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On Wed, Jul 31, 2019 at 4:20 PM Hendrik Boom <hendrik@topoi.pooq.com> wrote:
>
> There is, of course, also the question what would happen on nonintel or
> older machines if they don't have those ENDBR64 or ENDBR32
> instructions in the hardware.
>
I read somewhere that those instructions look like no-ops on older
machines.
>
> (Such as, perhaps, an actual AMD-manufactured AMD64? Like my
> 10-year-old AMD server?)
>
> Do we now have two distinct platforms to support?
>
It could be a configure-time choice. I wouldn't call that two distinct
platforms, more like two variants of the same platform.
Just speculating here. All this needs to be discussed and agreed on, of
course.
- Xavier Leroy
> -- hendrik
>
> >
> >
> > >
> > > There's also some stuff with shadow stacks which looks a lot more
> > > complicated and I didn't fully understand. The whole thing is
> > > described in:
> > >
> > >
> > >
> https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf
> > > https://lwn.net/Articles/758245/
> > >
> > >
> > I don't understand how these shadow stacks are supposed to interact with
> > exception handling, either Caml-style or C++/Java style.
> >
> > Kind regards,
> >
> > - Xavier Leroy
> >
> >
> > > Unfortunately (but for obvious reasons) every asm object in a program
> > > must be compiled with CET in order to enable the feature for the
> > > program as a whole. This means that any mixed OCaml/C program can't
> > > benefit from CET even in the C parts, unless we also support this in
> > > the OCaml parts.
> > >
> > > Has anyone looked into supporting this kind of thing in the amd64
> > > backend?
> > >
> > > (I looked at the OCaml trunk and couldn't see any relevant commits,
> > > but maybe I missed something in my grepping).
> > >
> > > Rich.
> > >
>
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next prev parent reply other threads:[~2019-07-31 15:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 14:28 Richard W.M. Jones
2019-07-25 15:52 ` Gerd Stolpmann
2019-07-25 19:24 ` Hendrik Boom
2019-07-31 12:05 ` Xavier Leroy
2019-07-31 14:19 ` Hendrik Boom
2019-07-31 15:21 ` Xavier Leroy [this message]
2019-07-31 17:40 ` Ivan Gotovchits
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