[PATCH] S390: Support PLT and GOT references in check-localplt.

[Stefan Liebler]

On 08/18/2016 12:42 PM, Stefan Liebler wrote:
> On 08/17/2016 03:48 PM, Florian Weimer wrote:
>> On 08/09/2016 04:22 PM, Stefan Liebler wrote:
>>> On 08/09/2016 03:53 PM, Florian Weimer wrote:
>>>> On 08/09/2016 03:34 PM, Stefan Liebler wrote:
>>>>> After the commits __libc_memalign is only called in
>>>>> elf/dl-minimal.c in
>>>>> malloc() function in ld.so and gcc -O2/-O3 leads to R_390_GLOB_DAT
>>>>> instead of R_390_JMP_SLOT. __libc_memalign is called via
>>>>> function-pointer loaded from GOT instead of calling via a plt-stub.
>>>>
>>>> Huh.  I wonder if this is intended.  Surely the malloc
>>>> implementation in
>>>> elf/dl-minimal.c should always call the __libc_memalign implementation
>>>> in the same file?
>>>>
>>>> Thanks,
>>>> Florian
>>>>
>>>
>>> Please have a look at the other localplt.data files, e.g.
>>> sysdeps/x86_64/localplt.data:
>>> # The dynamic loader uses __libc_memalign internally to allocate aligned
>>> # TLS storage. The other malloc family of functions are expected to
>>> allow
>>> # user symbol interposition.
>>> ld.so: __libc_memalign + RELA R_X86_64_GLOB_DAT
>>>
>>> All contains the __libc_memalign relocation.
>>> On s390x it has also existed before but a plt-stub was used. If you now
>>> use the compiler flag -fno-optimize-sibling-calls you'll get the
>>> plt-stub as before. With this optimization the relocation is done via a
>>> function pointer.
>>
>> Okay, but shouldn't be __libc_memalign in dl-minimal.c declared as
>> attribute_hidden?
>>
>> Thanks,
>> Florian
>>
> I don't know. Can you simply do this as __libc_memalign is also
> mentioned in elf/Versions file?
> ld {
>   GLIBC_2.0 {
>     # Function from libc.so which must be shared with libc.
>     __libc_memalign; calloc; free; malloc; realloc;
>
>     _r_debug;
>   }
>

Is there any news about __libc_memalign?
Otherwise I'd like to commit this patch.
I think if you change something about __libc_memalign you have to touch 
the other architectures as well.

Bye
Stefan