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 15:09:27 +0200 [thread overview]
Message-ID: <87d0jguxdk.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <1085273942.3137.1560517301721.JavaMail.zimbra@efficios.com> (Mathieu Desnoyers's message of "Fri, 14 Jun 2019 09:01:41 -0400 (EDT)")
* Mathieu Desnoyers:
> But my original issue remains: if I define a variable called __rseq_handled
> within either the main executable or the preloaded library, it overshadows
> the libc one:
>
> efficios@compudjdev:~/test/libc-sym$ ./a
> __rseq_handled main: 0 0x56135fd5102c
> __rseq_abi.cpu_id main: 29 0x7fcbeca6d5a0
> efficios@compudjdev:~/test/libc-sym$ LD_PRELOAD=./s.so ./a
> __rseq_handled s.so: 0 0x558f70aeb02c
> __rseq_abi.cpu_id s.so: -1 0x7fdca78b7760
> __rseq_handled main: 0 0x558f70aeb02c
> __rseq_abi.cpu_id main: 27 0x7fdca78b7760
>
> Which is unexpected.
Why is this unexpected? It has to be this way if the main program uses
a copy relocation of __rseq_handled. As long as there is just one
address across the entire program and ld.so initializes the copy of the
variable that is actually used, everything will be fine.
Thanks,
Florian
next prev parent reply other threads:[~2019-06-14 13:09 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 [this message]
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
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
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