Re: [PATCH v8 RESEND 6/6] common: honor CONFIG_CC_SPLIT_SECTIONS also for assembly functions

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

I am not very familiar with CC_SPLIT_SECTIONS. But I will try to answer 
the Arm questions.
On 13/03/2025 08:10, Jan Beulich wrote:
> Leverage the new infrastructure in xen/linkage.h to also switch to per-
> function sections (when configured), deriving the specific name from the
> "base" section in use at the time FUNC() is invoked.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Tested-by: Luca Fancellu <luca.fancellu@xxxxxxx> # arm
> ---
> TBD: Since we use .subsection in UNLIKELY_START(), a perhaps not really
>       wanted side effect of this change is that respective out-of-line
>       code now moves much closer to its original (invoking) code.
>
> TBD: Of course something with the same overall effect, but less
>       impactful might do in Config.mk. E.g. $(filter-out -D%,$(3))
>       instead of $(firstword (3)). In fact Roger wants the detection to
>       be in Kconfig, for LIVEPATCH to depend on it. Yet the whole
>       underlying discussion there imo would first need settling (and
>       therefore reviving).
>
> Note that we'd need to split DATA() in order to separate r/w, r/o, and
> BSS contributions. Further splitting might be needed to also support
> more advanced attributes (e.g. merge), hence why this isn't done right
> here. Sadly while a new section's name can be derived from the presently
> in use, its attributes cannot be. Perhaps the only thing we can do is
> give DATA() a 2nd mandatory parameter. Then again I guess most data
> definitions could be moved to C anyway.
>
> An alternative to the "override" in arm64/head.S would be to use
> LABEL{,_LOCAL}() instead of FUNC{,_LOCAL}() there. Yet that would also
> lose the type information then. Question is whether the annotated ranges
> really are "functions" in whichever wide or narrow sense.

They are functions. So I would prefer if we keep FUNC{,_LOCAL} and do 
the override as proposed in this patch..
Also, I think you want to move some of the override from the previous 
patches to this patch.
Cheers,

--
Julien Grall