Re: [PATCH 15/32] efi: lmb: Avoid access to _start

[Tom Rini]

On Mon, Feb 03, 2025 at 10:42:08AM -0700, 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. Disable this reservation for
> the EFI app.
> 
> Signed-off-by: Simon Glass <s...@chromium.org>
> ---
> 
>  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);

What prevents U-Boot from overwriting itself, with U-Boot commands? Also
how is this linking today? I see lmb_reserve_uboot_region in
efi-x86_app64 for example.

-- 
Tom

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