On Thu, 12 Apr 2018 08:13:43 -0400
Rick Barlow <rrhbar...@gmail.com> wrote:

> We have started seeing a rash of errors on some of our Linux virtual
> servers. The message we see on the virtual machine console is "Unknown
> program exception: 0028 [#1] SMP". It appears to only affect servers that
> were recently patched to kernel level "2.6.32-696.23.1.el6.s390x #1 SMP Sat
> Feb 10 11:11:31 EST 2018". It does not affect all of our servers that were
> recently patched. I suspect that it might be related to patches related to
> Spectre. I did a google search and did not get any hits on the message. I
> expect our Linux team will contact Red Hat support.

Program check 28 is ALET-specification exception. It is very unlikely that
Linux causes this exception. The only piece of code that uses the access
register mode is the clock_gettime() function in the vdso code. And then
only for the CPUCLOCK_VIRT clock source with a constant ALET.

blue skies,

"Reality continues to ruin my life." - Calvin.

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