From: Florian Weimer <fweimer@redhat.com>
To: Siddhesh Poyarekar <siddhesh@gotplt.org>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH] Fix glibc 2.34 ABI omission (missing GLIBC_2.34 in dynamic loader)
Date: Mon, 13 Dec 2021 13:15:03 +0100 [thread overview]
Message-ID: <874k7c1z20.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <026b3d7a-7de3-3f7e-d59e-85fe7514eb54@gotplt.org> (Siddhesh Poyarekar's message of "Wed, 8 Dec 2021 22:29:01 +0530")
* Siddhesh Poyarekar:
> On 12/8/21 15:16, Florian Weimer via Libc-alpha wrote:
>> The glibc 2.34 release really should have added a GLIBC_2.34
>> symbol to the dynamic loader. With it, we could move functions such
>> as dlopen or pthread_key_create that work on process-global state
>> into the dynamic loader (once we have fixed a longstanding issue
>> with static linking). Without the GLIBC_2.34 symbol, yet another
>> new symbol version would be needed because old glibc will fail to
>> load binaries due to the missing symbol version in ld.so that newly
>> linked programs will require.
>> This needs to be backported to the glibc 2.34 release branch as
>> well,
>> where hopefully all distributions will pick it up eventually.
>
> ISTM we could move symbols between ld.so and libc.so at will, without
> bumping symbol versions because they'll always be used together. In
> that sense, maybe we should not really consider such moves as ABI
> events at all?
It's only possible to move symbols if version nodes exist on both
sides. Therefore, this patch adds a version node to ld.so.
Without the version node, a binary linked against newer glibc will start
referencing GLIBC_2.34 in ld.so after a symbol move to ld.so. The lazy
bindign consistency check for symbol version nodes in unpatch old glibc
2.34 will then reject to load such binaries, even though a symbol
definition would be found during binding (as you point out).
Thanks,
Florian
next prev parent reply other threads:[~2021-12-13 12:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 9:46 Florian Weimer
2021-12-08 9:56 ` Andreas Schwab
2021-12-08 10:06 ` Florian Weimer
2021-12-08 10:20 ` Andreas Schwab
2021-12-08 10:28 ` Florian Weimer
2021-12-08 14:06 ` H.J. Lu
2021-12-24 19:01 ` Florian Weimer
2022-01-13 17:22 ` Carlos O'Donell
2022-01-13 17:32 ` Florian Weimer
2021-12-08 16:59 ` Siddhesh Poyarekar
2021-12-13 12:15 ` Florian Weimer [this message]
2021-12-13 14:54 ` Siddhesh Poyarekar
2022-01-13 17:56 ` Carlos O'Donell
2022-01-13 18:00 ` Carlos O'Donell
2022-01-22 16:08 ` H.J. Lu
2022-01-24 14:31 ` Florian Weimer
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