[PATCH 3/6] bfd: refine handling of relocations between debugging sections

[Jan Beulich]

On 09.03.2021 03:24, Alan Modra wrote:
> Does this work for you?
> 
> 	* elf.c (bfd_elf_generic_reloc): Make references between debug
> 	sections use section relative values.
> 
> diff --git a/bfd/elf.c b/bfd/elf.c
> index 553fa65a11..5331a7064a 100644
> --- a/bfd/elf.c
> +++ b/bfd/elf.c
> @@ -1302,8 +1302,7 @@ const char *const bfd_elf_section_type_names[] =
>     change anything about the way the reloc is handled, since it will
>     all be done at final link time.  Rather than put special case code
>     into bfd_perform_relocation, all the reloc types use this howto
> -   function.  It just short circuits the reloc if producing
> -   relocatable output against an external symbol.  */
> +   function, or should call this function for relocatable output.  */
>  
>  bfd_reloc_status_type
>  bfd_elf_generic_reloc (bfd *abfd ATTRIBUTE_UNUSED,
> @@ -1323,6 +1322,19 @@ bfd_elf_generic_reloc (bfd *abfd ATTRIBUTE_UNUSED,
>        return bfd_reloc_ok;
>      }
>  
> +  /* In some cases the relocation should be treated as input section
> +     relative, as when linking ELF DWARF into PE COFF.  Many ELF
> +     targets lack section relative relocations and instead use
> +     ordinary absolute relocations for references between DWARF
> +     sections.  That is arguably a bug in those targets but it happens
> +     to work for the usual case of linking to non-loaded ELF debug
> +     sections with VMAs forced to zero.  PE COFF on the other hand
> +     doesn't allow a section VMA of zero.  */
> +  if (output_bfd == NULL
> +      && (symbol->section->flags & SEC_DEBUGGING) != 0
> +      && (input_section->flags & SEC_DEBUGGING) != 0)
> +    reloc_entry->addend -= symbol->section->output_section->vma;
> +
>    return bfd_reloc_continue;
>  }
>  


Looks to be working fine. Just a question on the comment text:
Don't you mean "output section relative" in the first sentence?

Jan