Re: [PATCH 2/4] ARM: Fix register constraints in run_in_exception_handler()

[Julien Grall <julien@xxxxxxx>]

Hi Andrew,

On 10/02/2025 22:41, Andrew Cooper wrote:
> On 10/02/2025 9:31 pm, Julien Grall wrote:
> > On 10/02/2025 09:21, Oleksii Kurochko wrote:
> > > On 2/8/25 1:02 AM, Andrew Cooper wrote:
> > > > Right now, run_in_exception_handler() takes an input in an arbitrary
> > > > register,
> > > > and clobbers BUG_FN_REG.  This causes the compiler to calculate fn
> > > > in the
> > > > wrong regsiter.
> > > Probably, we should give a chance for the patch which suggests to use
> > > GENERIC_BUG_FRAME:
> > >     https://lore.kernel.org/xen-
> > > devel/8fdb98350ae4fc6029738d0aabe13a57e1945a50.1680086655.git.oleksii.kurochko@xxxxxxxxx/
> > That would be the ideal if someone has time for it. Otherwise, patch
> > #3 needs to be modified (see my answer on patch #2).
> >
> > But I would also be ok with this as a stop-gap for the time being.
> Getting ARM onto GENERIC_BUG_FRAME would definitely be best all around,
> but that is an almost-2-year-old patch with an open "it doesn't compile
> on ARM32" issue.
>
> I presume that all which is wanted is *a* solution that compiles (and
> works) everywhere we support?
Correct. Looking at the previous e-mail, it sounds like the patch was 
meant to work but it wasn't tested with older compilers and the commit 
message needed some rewording to mention what was tested.
Cheers,

--
Julien Grall