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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: [RFC PATCH glibc 1/4] glibc: Perform rseq(2) registration at nptl init and thread creation (v4)
Date: Mon, 14 Jan 2019 20:37:01 +0100	[thread overview]
Message-ID: <87y37n8202.fsf@oldenburg2.str.redhat.com> (raw)
In-Reply-To: <394676913.486.1547493757710.JavaMail.zimbra@efficios.com> (Mathieu Desnoyers's message of "Mon, 14 Jan 2019 14:22:37 -0500 (EST)")

* Mathieu Desnoyers:

> ----- On Jan 14, 2019, at 10:55 AM, Florian Weimer fweimer@redhat.com wrote:
>
>> * Mathieu Desnoyers:
>> 
>>> Therefore, both symbols will end up in
>>> sysdeps/unix/sysv/linux/Versions.
>> 
>> I'm not sure what you mean by that.  The physical location in the
>> directory tree has little effect on which shared object the symbol is
>> placed in; that will need other changes.
>
> I'm currently moving the symbol definitions to csu/rseq-sym.c. On Linux,
> its content is overridden by a new sysdeps/unix/sysv/linux/rseq-sym.c
> which contains both __rseq_abi and __rseq_refcount symbols. On other
> platforms, it is a stub file.

You don't need a stub file if you use the “ifeq ($(subdir),csu)”
construct.

The other question is whether this belongs into the csu subdirectory.
Since TLS is not available in ld.so, the initialization would have to
happen rather late, after relocation, but before ELF constructors are
run.

(A side effect is that the rseq area would not be usable from IFUNC
resolvers.)

Thanks,
Florian

  reply	other threads:[~2019-01-14 19:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-04 19:21 [RFC PATCH glibc 1/4] glibc: Perform rseq(2) registration at nptl init and thread creation (v4) Mathieu Desnoyers
2018-12-04 19:21 ` [RFC PATCH glibc 2/4] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux Mathieu Desnoyers
2018-12-04 19:44 ` [RFC PATCH glibc 1/4] glibc: Perform rseq(2) registration at nptl init and thread creation (v4) Florian Weimer
2018-12-04 19:50   ` Mathieu Desnoyers
2018-12-11 10:40 ` Florian Weimer
2019-01-10 20:31   ` Mathieu Desnoyers
2019-01-11  1:11     ` Mathieu Desnoyers
2019-01-14 18:57       ` Florian Weimer
2019-01-14 18:55     ` Florian Weimer
2019-01-14 19:22       ` Mathieu Desnoyers
2019-01-14 19:37         ` Florian Weimer [this message]
2019-01-14 20:27           ` Mathieu Desnoyers

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