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Re: [PATCH] Remove unnecessary IFUNC dispatch for __memset_chk.
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: Zack Weinberg <zackw at panix dot com>, Andreas Schwab <schwab at linux-m68k dot org>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 11 Aug 2015 12:09:55 -0700
- Subject: Re: [PATCH] Remove unnecessary IFUNC dispatch for __memset_chk.
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- References: <55C76FCD dot 5020607 at panix dot com> <CAMe9rOoAWjRma_mG_FazVh3FGOyiGJ=g82=bsfGqa-COnt5p1g at mail dot gmail dot com> <55C78525 dot 40402 at panix dot com> <CAMe9rOrKg8nzB67+OCXz5n1u7ZLnJncpX7J6KkEXqe0Bra843w at mail dot gmail dot com> <55C79AD8 dot 3070301 at panix dot com> <20150810030920 dot GE23550 at vapier> <20150810211200 dot GA17734 at domone> <CAKCAbMia4RCA7X0YHYeXC6eAGCxzDqhWrMiGS4NxA-cDxFioVw at mail dot gmail dot com> <20150811080451 dot GA6280 at domone> <CAMe9rOpjYBG9vHPFmJNAPQ02fhq_F_ZqoNprVsAkGCS=ZHEpqQ at mail dot gmail dot com> <20150811190303 dot GA4134 at domone>
On Tue, Aug 11, 2015 at 12:03 PM, OndÅej BÃlka <neleai@seznam.cz> wrote:
> On Tue, Aug 11, 2015 at 10:00:39AM -0700, H.J. Lu wrote:
>> On Tue, Aug 11, 2015 at 1:04 AM, OndÅej BÃlka <neleai@seznam.cz> wrote:
>> >>
>> > Simple, we return null. Following causes segmentation fault.
>> >
>> > gcc -fPIC -shared x.c -o libx.so
>> > void foo (int x) __attribute__ ((ifunc ("resolve_foo")));
>> >
>> > int foo_impl(int x)
>> ^^^^^^^^^^^^^^^^^^^^
>>
>> This should be static.
>>
> 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.
--
H.J.