From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Szabolcs Nagy <szabolcs.nagy@arm.com>,
rrh.henry@gmail.com
Subject: Re: RFC: Remove --disable-hidden-plt
Date: Tue, 6 Apr 2021 14:12:41 -0300 [thread overview]
Message-ID: <28ab0b62-2b14-4fd2-b333-abb1d91fa714@linaro.org> (raw)
In-Reply-To: <CAMe9rOqaFqQy_PA-07brLm+_4YjFPbqsdxxy5jWg=u7ya=MOkw@mail.gmail.com>
On 03/04/2021 14:41, H.J. Lu via Libc-alpha wrote:
> --disable-hidden-plt was added by
>
> commit 749a9a4fbfd261e2d9811d9bc4507478c2f7cc58
> Author: Roland McGrath <roland@gnu.org>
> Date: Tue Oct 1 08:45:44 2002 +0000
>
> 2002-10-01 Roland McGrath <roland@frob.com>
>
> * config.h.in (NO_HIDDEN): New #undef.
> * include/libc-symbols.h [! NO_HIDDEN]: Add this condition to
> nonempty definitions of hidden_proto et al.
> * configure.in: Grok --disable-hidden-plt to define NO_HIDDEN.
> * configure: Regenerated.
> * sysdeps/mach/hurd/configure.in: Always define NO_HIDDEN.
> * sysdeps/mach/hurd/configure: Regenerated.
>
> It doesn't work on x86-64:
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=27692
>
> Should it be removed?
>
My take is to remove it. Besides the reasons noted by Szabolcs [1],
some symbols interposition are not really possible on some scenarios
(for instance intra IFUNC call through hidden symbol on i686 and ppc32),
it requires more development effort (as any configure switch and we
will probably need a configure check to see if *all* supposed intra
calls are actually being called through PLT and fix bugs with missing
support), there is no clear advantage of providing such functionality,
and it broken on every architecture for some time (at least since
2.27).
However it seems it will still need to support it internally for
Hurd and it does catch a potential issue where some implementation
uses a non intended interface (such as __hidden_ver1).
I tried to understand why Roland's has added it in the first place,
but there is no discussion about it on libc-alpha in Sep/Oct 2002.
[1] https://sourceware.org/bugzilla/show_bug.cgi?id=27692#c7
next prev parent reply other threads:[~2021-04-06 17:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-03 17:41 H.J. Lu
2021-04-06 17:12 ` Adhemerval Zanella [this message]
2021-04-06 17:18 ` Samuel Thibault
2021-04-06 17:39 ` Adhemerval Zanella
2021-04-06 18:03 ` Samuel Thibault
2021-04-06 18:15 ` Adhemerval Zanella
2021-04-06 18:43 ` Samuel Thibault
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