Bug#996557: linux-image-5.14.0-3-686-pae-unsigned: just about every sse2 program crashes with a SIGFPE

[Salvatore Bonaccorso <carnil@debian.org>]

Control: tags -1 + moreinfo

Hi

On Fri, Oct 15, 2021 at 02:52:17PM +0200, Jiri Palecek wrote:
> Package: src:linux
> Version: 5.14.12-1
> Severity: serious
> X-Debbugs-Cc: Jiri Palecek <jpalecek@web.de>
> 
> Dear Maintainer,
> 
> when I booted my system with the latest kernel from unstable, many of
> the applications didn't work. That includes plasmashell (so I couldn't
> log in into plasma) and chromium.
> 
> I ran xterm (which worked) and some of these failing programs under gdb
> and found they all tripped on some sse2 instructions with a
> SIGFPE. However, all the programs work under the kernel from
> linux-image-5.14.0-2-xxxx.

This is interesting as looking at the commits between 5.14.9 and
5.14.12 there does not seem to be much related. As pointed out by Ben
offlist, the only plausible commit in this area might be 0723d4f8b179d
"x86/fpu: Restore the masking out of reserved MXCSR bits".

Can you thus please: Verify the issue is still present in 5.14.15 and
furthermore try to bisect the commit which introduces the problem for
you. In particular check if the 0723d4f8b179d commit is the culprit.

Regards,
Salvatore