From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: Chris Kennelly <ckennelly@google.com>
Cc: libc-coord@lists.openwall.com,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"carlos@redhat.com" <carlos@redhat.com>,
libc-alpha <libc-alpha@sourceware.org>
Subject: Re: [libc-coord] Re: RSEQ symbols: __rseq_size, __rseq_flags vs __rseq_feature_size
Date: Tue, 20 Sep 2022 12:51:11 +0100 [thread overview]
Message-ID: <YympLxofJVAJVyDj@arm.com> (raw)
In-Reply-To: <CAEE+ybkXCYoX73ksO0yutpc+4QZ_RuKnLxquVymzwj01d0=x-g@mail.gmail.com>
The 09/16/2022 11:41, Chris Kennelly wrote:
> > >
> > > 2) Implement the entire function as IFUNC and select whether a rseq or
> > > non-rseq implementation should be used at C startup. The tradeoff
> > > here is code size vs speed, and using IFUNC for things like malloc
> > > may add additional constraints on the startup order.
> >
>
> IFUNC has significant performance overheads as well. For frequently used
> code (like memcpy), avoiding them has been an optimization for us (
> https://research.google/pubs/pub50338/) even if it leaves some nominal
> microbenchmark performance on the table.
only in static linked exe. which is not the important case for distros
that want the ability to update the libc with security fixes.
glibc is not optimized for static linking, if that's a requirement that
should be a separate discussion (it's not just about ifunc).
prev parent reply other threads:[~2022-09-20 11:51 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 14:36 Mathieu Desnoyers
2022-09-16 14:44 ` Mathieu Desnoyers
2022-09-16 15:29 ` Florian Weimer
2022-09-16 15:41 ` [libc-coord] " Chris Kennelly
2022-09-16 21:32 ` Florian Weimer
2022-09-17 11:51 ` Mathieu Desnoyers
2022-09-17 14:45 ` Florian Weimer
2022-09-17 15:25 ` Mathieu Desnoyers
2022-09-20 11:51 ` Szabolcs Nagy [this message]
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=YympLxofJVAJVyDj@arm.com \
--to=szabolcs.nagy@arm.com \
--cc=carlos@redhat.com \
--cc=ckennelly@google.com \
--cc=libc-alpha@sourceware.org \
--cc=libc-coord@lists.openwall.com \
--cc=mathieu.desnoyers@efficios.com \
/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).