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Re: [PATCH] Remove unnecessary IFUNC dispatch for __memset_chk.

On Tue, Aug 11, 2015 at 12:41 PM, Alexander Monakov <> 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.


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