From nobody Sun Dec 28 00:48:25 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADFF1C4332F for ; Wed, 13 Dec 2023 22:53:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230358AbjLMWxP (ORCPT ); Wed, 13 Dec 2023 17:53:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229698AbjLMWxN (ORCPT ); Wed, 13 Dec 2023 17:53:13 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD9A085 for ; Wed, 13 Dec 2023 14:53:19 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97306C433C7; Wed, 13 Dec 2023 22:53:18 +0000 (UTC) Date: Wed, 13 Dec 2023 17:54:03 -0500 From: Steven Rostedt To: LKML , Linux Trace Kernel Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers Subject: [PATCH] ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI Message-ID: <20231213175403.6fc18540@gandalf.local.home> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: "Steven Rostedt (Google)" As the ring buffer recording requires cmpxchg() to work, if the architecture does not support cmpxchg in NMI, then do not do any recording within an NMI. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 8f8887f025c9..caaffcdc6350 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3719,6 +3719,12 @@ rb_reserve_next_event(struct trace_buffer *buffer, int nr_loops =3D 0; int add_ts_default; =20 + /* ring buffer does cmpxchg, make sure it is safe in NMI context */ + if (!IS_ENABLED(CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG) && + (unlikely(in_nmi()))) { + return NULL; + } + rb_start_commit(cpu_buffer); /* The commit page can not change after this */ =20 --=20 2.42.0