linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Florian Weimer <fweimer@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Rich Felker <dalias@libc.org>, carlos <carlos@redhat.com>,
	Joseph Myers <joseph@codesourcery.com>,
	Szabolcs Nagy <szabolcs.nagy@arm.com>,
	libc-alpha <libc-alpha@sourceware.org>,
	Thomas Gleixner <tglx@linutronix.de>, Ben Maurer <bmaurer@fb.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Will Deacon <will.deacon@arm.com>,
	Dave Watson <davejwatson@fb.com>, Paul Turner <pjt@google.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-api <linux-api@vger.kernel.org>
Subject: Re: [RFC PATCH v4 1/5] glibc: Perform rseq(2) registration at nptl init and thread creation
Date: Mon, 26 Nov 2018 09:28:34 +0100	[thread overview]
Message-ID: <87bm6cqm31.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <1758017676.12041.1543007347347.JavaMail.zimbra@efficios.com> (Mathieu Desnoyers's message of "Fri, 23 Nov 2018 16:09:07 -0500 (EST)")

* Mathieu Desnoyers:

> Using a "weak" symbol in early adopter libraries is important, so they
> can be loaded together into the same process without causing loader
> errors due to many definitions of the same strong symbol.

This is not how ELF dynamic linking works.  If the symbol name is the
same, one definition interposes the others.

You need to ensure that the symbol has the same size everywhere, though.
There are some tricky interactions with symbol versions, too.  (The
interposing libraries must not use symbol versioning.)

Thanks,
Florian

  reply	other threads:[~2018-11-26  8:28 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-21 18:39 [RFC PATCH v4 1/5] glibc: Perform rseq(2) registration at nptl init and thread creation Mathieu Desnoyers
2018-11-21 18:39 ` [RFC PATCH v4 2/5] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux Mathieu Desnoyers
2018-11-22 14:36 ` [RFC PATCH v4 1/5] glibc: Perform rseq(2) registration at nptl init and thread creation Rich Felker
2018-11-22 15:04   ` Mathieu Desnoyers
2018-11-22 15:11     ` Florian Weimer
2018-11-22 15:17       ` Rich Felker
2018-11-22 15:21         ` Florian Weimer
2018-11-22 15:33           ` Mathieu Desnoyers
2018-11-22 15:44             ` Rich Felker
2018-11-22 16:24             ` Szabolcs Nagy
2018-11-22 18:35               ` Mathieu Desnoyers
2018-11-22 19:01                 ` Rich Felker
2018-11-22 19:36                   ` Mathieu Desnoyers
2018-11-22 15:14     ` Rich Felker
2018-11-22 15:47       ` Mathieu Desnoyers
2018-11-22 16:28         ` Florian Weimer
2018-11-22 16:47           ` Mathieu Desnoyers
2018-11-22 16:59             ` Florian Weimer
2018-11-22 17:10               ` Rich Felker
2018-11-23 13:10                 ` Florian Weimer
2018-11-23 14:28                   ` Rich Felker
2018-11-23 17:05                     ` Mathieu Desnoyers
2018-11-23 17:30                       ` Rich Felker
2018-11-23 17:39                         ` Florian Weimer
2018-11-23 17:44                           ` Rich Felker
2018-11-23 18:01                             ` Florian Weimer
2018-11-23 17:52                         ` Mathieu Desnoyers
2018-11-23 18:35                           ` Rich Felker
2018-11-23 21:09                             ` Mathieu Desnoyers
2018-11-26  8:28                               ` Florian Weimer [this message]
2018-11-26 15:51                                 ` Mathieu Desnoyers
2018-11-26 16:03                                   ` Florian Weimer
2018-11-26 17:10                                     ` Rich Felker
2018-11-26 19:22                                       ` Mathieu Desnoyers
2018-12-03 21:30                                         ` Mathieu Desnoyers
2018-11-26 16:30                                   ` Mathieu Desnoyers
2018-11-26 17:07                                     ` Rich Felker
2018-12-05 17:24                                       ` Mathieu Desnoyers
2018-11-26 11:56                               ` Szabolcs Nagy
2018-11-22 17:29               ` Mathieu Desnoyers
2018-11-23 13:29                 ` Florian Weimer

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=87bm6cqm31.fsf@oldenburg.str.redhat.com \
    --to=fweimer@redhat.com \
    --cc=bmaurer@fb.com \
    --cc=boqun.feng@gmail.com \
    --cc=carlos@redhat.com \
    --cc=dalias@libc.org \
    --cc=davejwatson@fb.com \
    --cc=joseph@codesourcery.com \
    --cc=libc-alpha@sourceware.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    --cc=pjt@google.com \
    --cc=szabolcs.nagy@arm.com \
    --cc=tglx@linutronix.de \
    --cc=will.deacon@arm.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 NNTP newsgroup(s).