[PATCH] dwarf: Bail out if debug info needs relocation

[H.J. Lu]

On Mon, Sep 10, 2018 at 7:17 PM, Alan Modra <amodra@gmail.com> wrote:
> On Fri, Sep 07, 2018 at 12:58:32PM -0700, H.J. Lu wrote:
>>       PR ld/23425
>>       * dwarf2.c (find_abstract_instance): Bail out if debug info
>>       needs relocation.
>> ---
>>  bfd/dwarf2.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
>> index 8fadb5c4b6..bce5db9c7e 100644
>> --- a/bfd/dwarf2.c
>> +++ b/bfd/dwarf2.c
>> @@ -2839,6 +2839,9 @@ find_abstract_instance (struct comp_unit *   unit,
>>        total = info_ptr_end - info_ptr;
>>        if (!die_ref || die_ref >= total)
>>       {
>> +       /* Bail out if the debug info needs relocation.  */
>> +       if ((unit->stash->sec->flags & SEC_RELOC))
>> +         return TRUE;
>>         _bfd_error_handler
>>           (_("DWARF error: invalid abstract instance DIE ref"));
>>         bfd_set_error (bfd_error_bad_value);
>
> Every .debug_info section will have relocations, so this completely
> disables the error checking here.  Too much sweeping under the rug.

It disables error checking on relocatable files, not on executables
nor shared objects.

> I believe the problem is described by the comment just above this
> code: "We only support DW_FORM_ref_addr within the same file".
>

I don't believe find_abstract_instance should check if there are
relocation errors in a relocatable file.  What does my patch
change in binutils behavior?

-- 
H.J.