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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: libc-alpha <libc-alpha@sourceware.org>
Cc: Florian Weimer <fweimer@redhat.com>,
	"carlos@redhat.com" <carlos@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	x86@kernel.org, paulmck <paulmck@kernel.org>,
	Michael Jeanson <mjeanson@efficios.com>
Subject: Prevent inconsistent CPU state after sequence of dlclose/dlopen
Date: Fri, 10 Jan 2025 10:55:36 -0500	[thread overview]
Message-ID: <c606fd39-e835-44a6-a9be-9c6fab3c48fd@efficios.com> (raw)

Hi,

I was discussing with Mark Rutland recently, and he pointed out that a
sequence of dlclose/dlopen mapping new code at the same addresses in
multithreaded environments is an issue on ARM, and possibly on Intel/AMD
with the newer TLB broadcast maintenance.

I maintain the membarrier(2) system call, which provides a
MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE command for this
purpose. It's been there since Linux 4.16. It can be configured
out (CONFIG_MEMBARRIER=n), but it's enabled by default.

Calling this after dlclose() in glibc would prevent this issue.

Is it handled in some other way, or should we open a bugzilla
entry to track this ?

Thanks,

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

             reply	other threads:[~2025-01-10 15:55 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-10 15:55 Mathieu Desnoyers [this message]
2025-01-10 16:47 ` Prevent inconsistent CPU state after sequence of dlclose/dlopen Adhemerval Zanella Netto
2025-01-15 20:16   ` Mathieu Desnoyers
2025-01-10 16:54 ` Peter Zijlstra
2025-01-10 17:02   ` Mathieu Desnoyers
2025-01-10 17:10     ` Florian Weimer
2025-01-10 17:14       ` Adhemerval Zanella Netto
2025-01-10 17:15       ` Mathieu Desnoyers
2025-01-10 17:24         ` Adhemerval Zanella Netto
2025-01-10 17:35           ` Mathieu Desnoyers
2025-01-10 17:46         ` Florian Weimer
2025-01-10 19:16           ` Mathieu Desnoyers
2025-01-10 17:11     ` Peter Zijlstra
2025-01-10 18:41       ` Mark Rutland
2025-01-10 17:12     ` Adhemerval Zanella Netto
2025-01-10 17:04 ` Florian Weimer
2025-01-10 17:13   ` Mathieu Desnoyers
2025-01-10 18:33     ` Paul E. McKenney

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