[PATCH v4 13/29] efi: lmb: Avoid access to _start

[Simon Glass]

Hi Caleb,

On Thu, 27 Mar 2025 at 10:21, Caleb Connolly <caleb.connolly at linaro.org> wrote:
>
>
>
> On 2/15/25 04:22, Simon Glass wrote:
> > The app does not have this symbol. Also the memory where the app is
> > loaded is not under U-Boot's control.
> >
> > There is no sense in relocating from one alloced region to another.
> > U-Boot is not able to relocate to the top of memory, nor decide what
> > other parts of memory are used for.
> >
> > For these reasons, the EFI app skips relocation. It is not running at
> > the address pointed to by the _start symbol.
>
> is there a symbol or not? If there is could we have some "relocate in
> place" mechanism so that it's valid? When I (finally...) get around to
> re-sending the symbol lookup support it would be nice if it worked for
> the EFI app, and it relies on _start.

Can I leave you to do that clean-up/investigation in your series,
then? Tom has already reviewed this patch and it has been sitting here
for 6 weeks. I applied it yesterday.

> >
> > So disable this reservation for the EFI app.
> >
> > Signed-off-by: Simon Glass <sjg at chromium.org>
> > Reviewed-by: Tom Rini <trini at konsulko.com>
> > ---
> >
> > (no changes since v2)
> >
> > Changes in v2:
> > - Expand commit message to explains that EFI_APP skips relocation
> >
> >   lib/lmb.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/lmb.c b/lib/lmb.c
> > index 588787d2a90..420eae4d0b8 100644
> > --- a/lib/lmb.c
> > +++ b/lib/lmb.c
> > @@ -560,7 +560,8 @@ static void lmb_reserve_uboot_region(void)
> >               lmb_reserve_flags(rsv_start, bank_end - rsv_start + 1,
> >                                 LMB_NOOVERWRITE);
> >
> > -             if (gd->flags & GD_FLG_SKIP_RELOC)
> > +             if (!IS_ENABLED(CONFIG_EFI_APP) &&
> > +                 (gd->flags & GD_FLG_SKIP_RELOC))
> >                       lmb_reserve_flags((phys_addr_t)(uintptr_t)_start,
> >                                         gd->mon_len, LMB_NOOVERWRITE);
> >
>
> --
> Caleb (they/them)
>

Regards,
Simon