[PATCH] Remove unnecessary IFUNC dispatch for __memset_chk.

[H.J. Lu]

On Tue, Aug 11, 2015 at 12:41 PM, Alexander Monakov <amonakov@ispras.ru> wrote:
> On Tue, 11 Aug 2015, H.J. Lu wrote:
>> > Didn't know its explicitly forbidden to use nonstatic resolvers. Do we document that requirement somewhere?
>> > If not then we should add it to documentation.
>>
>> It makes no senses for IFUNC selector to return the address of
>> a global function, which may be preempted at run-time.
>
> That would be imposing a policy while providing a mechanism.
>
> I think there are plausible scenarios where returning a global function from
> an ifunc resolver would be natural.
>
> To give a specific example, imagine an ifunc symbol
> 'printf_fortified_opportunistically', which resolves to 'printf_chk' if it is
> available in the global namespace, or normal 'printf' otherwise.
>
> Such a symbol could be in any DSO, not necessarily libc, and thus it has to be
> able to pick up global symbol definitions.
>

By the nature of preemption, you have NO control over which definition
will be used at run-time.  It can be literally anything, including segfault.

-- 
H.J.