17 Sep
2019
17 Sep
'19
10:40 a.m.
Yes, I understand that a number of ISAs are vulnerable. The original paper by Kocher
clearly mentions both x86 and ARM.
The reason I forwwarded the question is that I'm not aware enough of all the VAX
variants to answer whether there are any VAXen with speculative execution. If no, then
we're done, the answer is easy. (That was the case when the question was asked for
PDP11s.) But if yes, then it becomes necessary to read the paper carefully to see if any
of the prerequisites are implemented in some VAX, and if yes, what the fix might look
like.
I'm reasonably comfortable assuming that the somewhat-related "Meltdown"
vulnerability doesn't show up in VAX, because that issue requires a designer who'd
implement page access checking in a way I would not expect a DEC engineer to do.
paul
On Sep 17, 2019, at 11:42 AM, Clem Cole <clemc at
ccc.com> wrote:
Paul - be careful. All CPU's post the IBM AGS that used branch prediction are
suspect. Russ Robelen (who was the 360/50 lead, worked on 360/90 and lead AGS) has the
speculative executing patent. I tweaked him when it all came out and said - look at what
you did.
What Russ and team are great ideas and we all have used them since they first published
about it. And the fact is that it took 40 years before someone even proposed that it was
an issue and could become security exploit (by some folks in German at a security
conference) and it Google 18 months to reduce it to practice.
?
On Tue, Sep 17, 2019 at 9:55 AM Paul Koning <paulkoning at comcast.net> wrote:
"Spectre" is one of two notorious bugs of modern CPUs involving speculative
execution. I rather doubt that VAX is affected by this but I suspect others here have a
lot more knowledge.
paul
Begin forwarded message:
From: coypu at sdf.org
Subject: VAX + Spectre
Date: September 17, 2019 at 5:32:42 AM EDT
To: port-vax at netbsd.org
So, this is a bug report:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86811
GCC would like to know if VAX needs Spectre-related work.
Are any of the VAXes ever made capable of speculative execution? the
first tech for doing it was in 1967, so not entirely far-fetched.
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