Re: [PATCH 5/7] x86/mkreloc: remove warning about relocations to RO section

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 18/03/2025 5:35 pm, Roger Pau Monne wrote:
> Relocations are now applied after having moved the trampoline, so there's no
> reason to warn about relocations to read-only sections.  The logic that
> apply the relocations would make sure they are applied against writable
> mappings.
>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
>  xen/arch/x86/efi/mkreloc.c | 5 -----
>  1 file changed, 5 deletions(-)
>
> diff --git a/xen/arch/x86/efi/mkreloc.c b/xen/arch/x86/efi/mkreloc.c
> index 375cb79d6959..a5a1969f2ee5 100644
> --- a/xen/arch/x86/efi/mkreloc.c
> +++ b/xen/arch/x86/efi/mkreloc.c
> @@ -216,11 +216,6 @@ static void diff_sections(const unsigned char *ptr1, 
> const unsigned char *ptr2,
>              exit(3);
>          }
>  
> -        if ( !(sec->flags & IMAGE_SCN_MEM_WRITE) )
> -            fprintf(stderr,
> -                    "Warning: relocation to r/o section %.8s:%08" PRIxFAST32 
> "\n",
> -                    sec->name, i - disp);
> -
>          printf("\t.word (%u << 12) | 0x%03" PRIxFAST32 "\n",
>                 reloc, sec->rva + i - disp - rva);
>          reloc_size += 2;

I'm on the fence about this.

Obviously we don't want a warning firing for good cases, but the
trampoline is special where the relocation is to a R/O section but we
don't apply the relocation in that position.

Is it possible to limit this to only trampoline_{start,end} and keep the
warning in general?

~Andrew