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SubjectRe: WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching)

* Ingo Molnar <mingo@kernel.org> wrote:

>
> * Andy Lutomirski <luto@kernel.org> wrote:
>
> > This sets up stack switching, including for SYSCALL. I think it's
> > in decent shape.
> >
> > Known issues:
> > - I think we're going to want a way to turn the stack switching on and
> > off either at boot time or at runtime. It should be fairly straightforward
> > to make it work.
> >
> > - I think the ORC unwinder isn't so good at dealing with stack overflows.
> > It bails too early (I think), resulting in lots of ? entries. This
> > isn't a regression with this series -- it's just something that could
> > be improved.
>
> Note that with the attached config on an Intel testbox I get the following new ORC
> unwinder warning during bootup:
>
> [ 12.200554] calling ghash_pclmulqdqni_mod_init+0x0/0x54 @ 1
> [ 12.209536] WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0
> [ 12.231388] initcall ghash_pclmulqdqni_mod_init+0x0/0x54 returned 0 after 23480 usecs
>
> Thanks,

Also note that the ORC warning goes away if CONFIG_PROVE_LOCKING is disabled.

Thanks,

Ingo

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