[PATCH 03/12] nptl/Makefile.in: Append $(SYMBOL_PREFIX) to symbol names

[Markos Chandras]

On 21 February 2013 17:05, Markos Chandras <markos.chandras at gmail.com> wrote:
> On 21 February 2013 15:23, Bernhard Reutner-Fischer
> <rep.dot.nop at gmail.com> wrote:
>> On 21 February 2013 16:07, Markos Chandras <markos.chandras at gmail.com> wrote:
>>> On 21 February 2013 14:03, Bernhard Reutner-Fischer
>>> <rep.dot.nop at gmail.com> wrote:
>>
>>>>> +       -Wl,-z,nodelete,-z,initfirst,-init=$(SYMBOL_PREFIX)__pthread_initialize_minimal_internal
>>>>
>>>> mhm. I am curious on which arch you needed this?
>>>>
>>>> PS: It is interesting to see that the -init part is sometimes
>>>> encountered by people but apparently never the -fini one as in
>>>> dl_cleanup?
>>>
>>> Hi Bernhard,
>>>
>>> It's needed by the Meta arch port which I just submitted. Meta
>>> prefixes symbols with "_". See the Rules.mak changes in the [07/12]
>>> patch (once it reaches the mailing list). It's also needed by
>>> h8300,bfin,i960 and v850 which also have SYMBOL_PREFIX=_
>>
>> ok, and why does it work for aforementioned fini, or do you just support static?
>
> Hi Bernhard,
>
> Now that I think about it, this patch is not needed. binutils 2.22 was
> "fixed" to not take into account the leading "_" underscore for arches
> anymore so there should be no problem during the linking phase. I will
> double check that removing this patch does not break anything.
>
> --
> Regards,
> Markos Chandras

Hi Bernhard,

I've done some tests. It seems it is needed in both cases. if the
linker does not find the symbol passed in -init/-fini parameters then
it uses the default one. That surprised me as I was expecting a link
failure instead of silently use the default symbol. So I looked at the
binutils code and I observed the following in bfd/elflink.c

      /* If there are initialization and/or finalization functions to
	 call then add the corresponding DT_INIT/DT_FINI entries.  */
      h = (info->init_function
	   ? elf_link_hash_lookup (elf_hash_table (info),
				   info->init_function, FALSE,
				   FALSE, FALSE)
	   : NULL);

So, if I understand this correctly, if the symbol passed in the -init
parameter can't be resolved, then this code returns NULL and no
DT_INIT entry is created. In other words, my libpthread.so.0 contains
the DT_INIT entry correctly (as it is prefixed with $(SYMBOL_PREFIX)
whereas libdl.so doesn't have a DT_FINI one even though it should
(assuming LDSO_NO_CLEANUP is not set)

After prefixing dl_cleanup with $(SYMBOL_PREFIX) a DT_FINI entry is
created for libdl.so. Thanks for noticing.

-- 
Regards,
Markos Chandras