17 Sep
2019
17 Sep
'19
10:49 a.m.
On Tue, Sep 17, 2019, 6:40 PM Paul Koning via cctalk <cctalk at classiccmp.org>
wrote:
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.
Early Vaxen are immune. Latter day ones require careful analysis since they
have some out of order things. I'm not expert enough to know for sure,
though, and the latter day stuff is half remembered from marketing material
for one of the final generations of Vax big iron before Alpha drove that
away... But I don't think many of these old beasts are still running even
if my half remembered stuff is right...
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.
I'm agree.
Warner
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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