[PATCH] x86: Check the versioned __tls_get_addr symbol

[H.J. Lu]

On Fri, Jan 19, 2018 at 6:00 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Fri, Jan 19, 2018 at 4:20 PM, Alan Modra <amodra@gmail.com> wrote:
>> On Fri, Jan 19, 2018 at 10:57:37AM -0800, H.J. Lu wrote:
>>> --- a/bfd/elfxx-x86.c
>>> +++ b/bfd/elfxx-x86.c
>>> @@ -856,7 +856,16 @@ _bfd_x86_elf_link_check_relocs (bfd *abfd, struct bfd_link_info *info)
>>>                                   htab->tls_get_addr,
>>>                                   FALSE, FALSE, FALSE);
>>>         if (h != NULL)
>>> -         elf_x86_hash_entry (h)->tls_get_addr = 1;
>>> +         {
>>> +           elf_x86_hash_entry (h)->tls_get_addr = 1;
>>> +
>>> +           /* Check the versioned __tls_get_addr symbol.  */
>>> +           while (h->root.type == bfd_link_hash_indirect)
>>> +             {
>>> +               h = (struct elf_link_hash_entry *) h->root.u.i.link;
>>> +               elf_x86_hash_entry (h)->tls_get_addr = 1;
>>> +             }
>>> +         }
>>
>> I think it would be a little more bomb proof to pass follow=TRUE on
>> the elf_link_hash_lookup call, and then always test the flag on the
>> real symbol (which would mean a patch to elf_i386_check_tls_transition
>> and elf_x86_64_check_tls_transition).  We have some really odd cases
>
> I'd like to keep the change as small as possible for backporting to
> 2.30.
>
>> in _bfd_elf_merge_symbol where a versioned symbol can end up pointing
>> at the undecorated symbol.  So it might be possible to have
>>   __tls_get_addr@VER -> __tls_get_addr -> __tls_get_addr@@VER
>> in which case you wouldn't set the flag on __tls_get_addr@VER.
>>
>
> But I do want to cover all bases.  Do you have a testcase to show
> such a scenario so that I can verify that it is covered?

This is what I checked into master and 2.30 branch.  We will
revisit it in the future if there is a testcase.


-- 
H.J.
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