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From: "fweimer at redhat dot com" <sourceware-bugzilla@sourceware.org>
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Subject: [Bug dynamic-link/28218] ld.so: ifunc resolver calls a lazy PLT.
 When does it work?
Date: Thu, 12 Aug 2021 07:36:34 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D28218

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |fweimer at redhat dot com

--- Comment #2 from Florian Weimer <fweimer at redhat dot com> ---
(In reply to Alan Modra from comment #1)
> > FreeBSD rtld resolves non-IRELATIVE relocations in all modules, then
> > IRELATIVE relocations in all modules.
> Yes, this is the correct way to do things, and the only general way to
> support cross-module ifunc resolvers that themselves might need to be
> relocated.  We have known this for a long time.  See for example
> https://gcc.gnu.org/legacy-ml/gcc-patches/2009-07/msg01307.html

Cross-module IFUNC resolvers that have relocation dependencies need more
deferral than just IRELATIVE relocations. Regular relocations which target =
an
IFUNC symbol need to be deferred, and copy relocations as well. Even that d=
oes
not completely address all cases.

My impression is that the glibc maintainers think that IFUNC resolvers must=
 not
use have relocation dependencies. This could mean that they can only be
implemented in assembler on some targets.

Initial comments on a proposal were positive:
https://sourceware.org/legacy-ml/libc-alpha/2017-01/msg00468.html But I thi=
nk
during later discussions, this approach was rejected.

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