[PATCH] Enable hidden visibility in libc.a compiled with PIE

[Szabolcs Nagy]

On 21/08/17 17:44, H.J. Lu wrote:
> On Mon, Aug 21, 2017 at 9:31 AM, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
>> On 08/08/17 17:40, H.J. Lu wrote:
>>> When building libc.a with PIE, enable hidden visibility to allow direct
>>> access to definitions within libc.a without using GOT.
>> ...
>>> -#if defined SHARED || defined LIBC_NONSHARED
>>> +#if defined SHARED || defined LIBC_NONSHARED \
>>> +  || (BUILD_PIE_DEFAULT && IS_IN (libc))
>>>  # define attribute_hidden __attribute__ ((visibility ("hidden")))
>>
>> btw what happens if this is enabled for non-pie libc.a ?
> 
> It makes those symbols in libc.a hidden.
> 
>> i'd expect that to work too (it prevents some symbol
>> interpositions?)
>>
> 
> You can't interpose any symbols in libc.a, PIE or non-PIE.
> What my patch does is to avoid GOT/PLT in PIE libc.a when
> accessing them within libc.a.
> 

yes, but my point is that the ifdef can be simplified
if it's valid for the non-pie case too.