From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Florian Weimer <fweimer@redhat.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: Wed, 12 Jun 2019 10:36:03 -0400 (EDT) [thread overview]
Message-ID: <512441263.43096.1560350163180.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <87blz27uio.fsf@oldenburg2.str.redhat.com>
----- On Jun 12, 2019, at 4:22 PM, Florian Weimer fweimer@redhat.com wrote:
> * Mathieu Desnoyers:
>
>>> It's the registration from libc.so which needs some care. In
>>> particular, we must not override an existing registration.
>>
>> OK, so it could check if __rseq_abi.cpu_id is -1, and only
>> perform registration if it is the case. Or do you have another
>> approach in mind ?
>
> No, __rseq_abi will not be shared with the outer libc, so the inner libc
> will always see -1 there, even if the outer libc has performed
> registration.
>
> libio/vtables.c has some example what you can do:
>
> /* In case this libc copy is in a non-default namespace, we always
> need to accept foreign vtables because there is always a
> possibility that FILE * objects are passed across the linking
> boundary. */
> {
> Dl_info di;
> struct link_map *l;
> if (!rtld_active ()
> || (_dl_addr (_IO_vtable_check, &di, &l, NULL) != 0
> && l->l_ns != LM_ID_BASE))
> return;
> }
>
> _IO_vtable_check would have to be replaced with your own function; the
> actual function doesn't really matter.
>
> The rtld_active check covers the static dlopen case, where
> rtld_active () is false in the inner libc.
Then out of curiosity, would it also work if I check for
if (!__libc_multiple_libcs)
in LIBC_START_MAIN ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2019-06-12 14:36 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-03 18:42 [PATCH 0/5] Restartable Sequences support for glibc 2.30 Mathieu Desnoyers
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
2019-06-14 13:59 ` Mathieu Desnoyers
[not found] ` <69a53ec2ce184af29c4cae58e0b2fb57@AcuMS.aculab.com>
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 [this message]
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
2019-05-03 18:42 ` [PATCH 3/5] support record failure: allow use from constructor Mathieu Desnoyers
2019-05-03 18:42 ` [PATCH 4/5] support: implement xpthread key create/delete (v2) Mathieu Desnoyers
2019-05-03 18:42 ` [PATCH 5/5] rseq registration tests (v4) Mathieu Desnoyers
2019-05-20 15:24 ` [PATCH 0/5] Restartable Sequences support for glibc 2.30 Mathieu Desnoyers
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