From: Florian Weimer <fweimer@redhat.com>
To: Chris Kennelly <ckennelly@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Paul Turner <pjt@google.com>, Peter Oskolkov <posk@posk.io>,
libc-alpha@sourceware.org <libc-alpha@sourceware.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: Aligning tcmalloc with glibc 2.35 rseq ABI
Date: Wed, 02 Feb 2022 09:41:06 +0100 [thread overview]
Message-ID: <875ypx1x0d.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <87mtja1fuz.fsf@oldenburg.str.redhat.com> (Florian Weimer's message of "Tue, 01 Feb 2022 21:39:16 +0100")
* Florian Weimer:
> * Chris Kennelly:
>
>> Thanks for the heads up.
>>
>> I did have a question about whether the new protocol would introduce
>> an extra memory reference while initializing a critical section.
>>
>> * With initial-exec TLS, I can directly reference __rseq_abi.
>> * With the new ABI, I might need to ask glibc for the address of the
>> registered rseq structure in its thread data.
>
> You can write __rseq_offset to a static/hidden variable in an ELF
> constructor, and then use pretty much the same assembler sequences as
> for initial-exec TLS on most architectures.
And now I'm kind of worried that we should be using ptrdiff_t for
__rseq_offset because that's what the initial-exec relocations use. 8-/
Thanks,
Florian
next prev parent reply other threads:[~2022-02-02 8:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-01 14:58 Mathieu Desnoyers
2022-02-01 20:33 ` Chris Kennelly
2022-02-01 20:39 ` Florian Weimer
2022-02-02 8:41 ` Florian Weimer [this message]
2022-02-02 11:36 ` Mathieu Desnoyers
2022-02-02 13:08 ` Mathieu Desnoyers
2022-02-02 15:01 ` Florian Weimer
2022-02-02 17:31 ` Carlos O'Donell
2022-02-02 22:28 ` Carlos O'Donell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=875ypx1x0d.fsf@oldenburg.str.redhat.com \
--to=fweimer@redhat.com \
--cc=ckennelly@google.com \
--cc=libc-alpha@sourceware.org \
--cc=mathieu.desnoyers@efficios.com \
--cc=pjt@google.com \
--cc=posk@posk.io \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).