[PATCH] AArch64: Check kernel version for SVE ifuncs

Florian Weimer fweimer@redhat.com
Thu Mar 14 16:52:06 GMT 2024


* Wilco Dijkstra:

> Hi Florian,
>
>> I generally prefer we fix the component that has the bug.  With that
>> approach, you'd have to to use your distribution contacts to request a
>> backport.
>
> The issue is present since SVE was added in 4.18 so it affects many
> kernels.  It is unlikely to be easy to backport since it relies on
> various other changes to how syscalls and register state is dealt
> with.
>
> Originally it was thought to be OK - and it would be if you only ever
> use SVE in vectorized loops. However using a few SVE instructions
> everywhere in applications breaks that model. Plus all the security
> features have increased the overhead of kernel traps in recent
> years...

Yes, that might be the case.

Can we hold off merging is for a bit?  I want to cross-checks a few
things internally before we go with the version check as proposed if
that's possible.

Thanks,
Florian



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