All of lore.kernel.org
 help / color / mirror / Atom feed
From: Florian Weimer <fweimer@redhat.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: 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>,
	Rich Felker <dalias@libc.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-api <linux-api@vger.kernel.org>
Subject: Re: [PATCH 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v10)
Date: Fri, 14 Jun 2019 15:53:15 +0200	[thread overview]
Message-ID: <87ef3wtgs4.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <26171199.3391.1560520033825.JavaMail.zimbra@efficios.com> (Mathieu Desnoyers's message of "Fri, 14 Jun 2019 09:47:13 -0400 (EDT)")

* Mathieu Desnoyers:

> ----- On Jun 14, 2019, at 3:42 PM, Florian Weimer fweimer@redhat.com wrote:
>
>> * Mathieu Desnoyers:
>> 
>>> +  /* Publicize rseq registration ownership.  This must be performed
>>> +     after rtld re-relocation, before invoking constructors of
>>> +     preloaded libraries.  */
>>> +  rseq_init ();
>> 
>> Please add a comment that IFUNC resolvers do not see the initialized
>> value.  I think this is okay because we currently do not support access
>> to extern variables in IFUNC resolvers.
>
> Do IFUNC resolvers happen to observe the __rseq_handled address that
> was internal to ld.so ?

They should observe the correct address, but they can access the
variable before initialization.  An initializer in ld.so will not have
an effect if an interposed definition initalized the variable to
something else.

> If so, we could simply initialize __rseq_handled twice: early before calling
> IFUNC resolvers, and after ld.so re-relocation.

No, I don't think this will make a difference.

Thanks,
Florian

  reply	other threads:[~2019-06-14 13:53 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190503184219.19266-1-mathieu.desnoyers@efficios.com>
2019-05-03 18:42 ` [PATCH 1/5] glibc: Perform rseq(2) registration at C startup and thread creation (v10) Mathieu Desnoyers
2019-05-27 11:19   ` Florian Weimer
2019-05-27 19:27     ` Mathieu Desnoyers
2019-05-29 15:45       ` Mathieu Desnoyers
2019-05-30 20:56         ` Mathieu Desnoyers
2019-05-31  8:06           ` Florian Weimer
2019-05-31 14:48             ` Mathieu Desnoyers
2019-05-31 15:46               ` Florian Weimer
2019-05-31 18:10                 ` Mathieu Desnoyers
2019-06-04 11:46                   ` Florian Weimer
2019-06-04 15:57                     ` Mathieu Desnoyers
2019-06-06 11:57                       ` Florian Weimer
2019-06-10 14:43                         ` Carlos O'Donell
2019-06-12 14:00                           ` Mathieu Desnoyers
2019-06-14 10:03                             ` Mathieu Desnoyers
2019-06-14 10:06                               ` Florian Weimer
2019-06-14 10:14                                 ` Mathieu Desnoyers
2019-06-14 11:35                                   ` Florian Weimer
2019-06-14 12:55                                     ` Mathieu Desnoyers
2019-06-14 13:01                                       ` Mathieu Desnoyers
2019-06-14 13:09                                         ` Florian Weimer
2019-06-14 13:18                                           ` Mathieu Desnoyers
2019-06-14 13:24                                             ` Florian Weimer
2019-06-14 13:34                                               ` Mathieu Desnoyers
2019-06-14 13:42                                                 ` Florian Weimer
2019-06-14 13:47                                                   ` Mathieu Desnoyers
2019-06-14 13:53                                                     ` Florian Weimer [this message]
2019-06-14 13:59                                                       ` Mathieu Desnoyers
2019-06-14 13:29                                         ` David Laight
2019-06-14 13:39                                           ` Mathieu Desnoyers
2019-06-12 14:16                         ` Mathieu Desnoyers
2019-06-12 14:22                           ` Florian Weimer
2019-06-12 14:36                             ` Mathieu Desnoyers
2019-06-12 14:43                               ` Florian Weimer
2019-05-03 18:42 ` [PATCH 2/5] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux (v4) Mathieu Desnoyers

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=87ef3wtgs4.fsf@oldenburg2.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.