Re: [PATCH v3 6/9] xen/arm64: bpi: Add missing code symbol annotations

["Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxx>]

On Tue, May 7, 2024 at 7:37 PM Julien Grall <julien@xxxxxxx> wrote:
>
>
>
> On 07/05/2024 17:55, Edgar E. Iglesias wrote:
> > On Tue, May 7, 2024 at 11:57 AM Julien Grall <julien@xxxxxxx> wrote:
> > Hi Julien,
>
> Hi Edgar,
>
> >
> > The reason I choose FUNC for the start of the symbol is because these
> > symbols contain
> > executable code (not only a table of pointers to code somewhere else)
> > and the ELF spec
> > says that STT_FUNC means the symbol contains functions or other executable
> > code (not only callable functions IIUC):
> >
> > "STT_FUNC The symbol is associated with a function or other executable 
> > code."
> > https://refspecs.linuxbase.org/elf/elf.pdf
> > (Symbol Table 1-20).
>
> Thanks for the pointer. I originally did intend to suggest the change,
> but then I saw the use of LABEL in x86 (such as svm_stgi_label). There
> are a few others example with LABEL_LOCAL.
>
> AFAICT, this is also executable code which the only difference that it
> is not meant to be called by someone else. Furthermore, LABEL is using
> DO_CODE_ALIGN(...) for the alignment which imply that it is intended to
> be used by executable code. So I thought the only difference was whether
> the label was intended to be used as a function.
>

Thanks Julien, yes, good points.

> >
> > I think using LABEL instead of GLOBAL for the _end labels of these
> > code sequences makes sense.
> > I'm happy to change the _start labels to LABEL too if you guys feel
> > that's better.
>
> I have to admit I am little confused with the difference between LABEL
> vs FUNC. I think I will need some guidance from Jan (he introduced
> linkage.h).
>

Jan, do you have any guidance on this specific case using FUNC , LABEL
(or something else)?

Cheers,
Edgar