From nobody Wed Dec 17 17:44:52 2025 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D3C811B151F; Thu, 4 Jul 2024 17:04:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720112673; cv=none; b=IXClgXoB3zpC0fEkVcsoH6vD4HJngPsNCC0vKf0l2tZnUakYUH4oz1LHPTZit7UDF5NzymHM0LnkEll0K7iKx2DyJ+IY84+FMAzob0L5mQkjkPcbbW1zHKlQoCq7j3JHFyIerLeNyUTXf+yFDz20xHT26ooK2iZh57tr6ayVfn4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720112673; c=relaxed/simple; bh=6eqRPcMlbj+4GVbr5+U0VOyaTZIgPiL/0X2LQRUJRks=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZZI2bpFumGO+skjt2KKNazJ+gC2CFajoNCKilfraLGSUee5+AnURRHNhFqY2nGVLDbrApCtB1SgCFj0Qu5d8DuHm/EdJVr+Q5jgoW8t4DGMXs+ARNdWSHIFhXve0tAPWSA315aCXxIq0LxJwSBX1VhqeLqwlj7GqieZTll++pzk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Bywyui1x; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=HKQ3CKiW; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Bywyui1x"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="HKQ3CKiW" From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1720112669; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=poySimGW+vu2aH2BbOceqnQrJPwa17Ey3AjyM7/+uMc=; b=Bywyui1xnrK/jO9L52kEa/1jMRp69HkTNh3x5+ZW1b15PNiwFB3HJI/xWYV6M1wvbHwbOA 1vsO4Ko83PhAEsObJYdzeTs8b1VNX/pc2OQdcQD7xu35a7g7icrCimdZPM0+Vub7+Oon0m 8DqoLHY8n3lBpdYsuCVJLW4x4jmjTwt7E8ZQ+1XMHlJ0PZhpvfhySJ81xSL7SNP/OYno8q JzmrLr+tM8d5V2rsmG/FsPlAULjZqf754QKrtZZYOSWq0CYzxDGoOrvwUAtQi9dmzcXodA Vl3wtCESbAOx2gLIKrpjan3RdOcvs6W6jLqNqWs9gfVRv/IwuNKfdbt6LcWXDg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1720112669; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=poySimGW+vu2aH2BbOceqnQrJPwa17Ey3AjyM7/+uMc=; b=HKQ3CKiWv88vO5FChtzpBmgGQ4x5UyxmAo2NufTRW6ZBJsVuoniA+JCupAOPY7jsPkfoGN HV1iBy7Ak7fGKNBA== To: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Adrian Hunter , Alexander Shishkin , Arnaldo Carvalho de Melo , Frederic Weisbecker , Ian Rogers , Ingo Molnar , Jiri Olsa , Kan Liang , Marco Elver , Mark Rutland , Namhyung Kim , Peter Zijlstra , Thomas Gleixner , Sebastian Andrzej Siewior Subject: [PATCH v5 2/7] task_work: Add TWA_NMI_CURRENT as an additional notify mode. Date: Thu, 4 Jul 2024 19:03:36 +0200 Message-ID: <20240704170424.1466941-3-bigeasy@linutronix.de> In-Reply-To: <20240704170424.1466941-1-bigeasy@linutronix.de> References: <20240704170424.1466941-1-bigeasy@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Adding task_work from NMI context requires the following: - The kasan_record_aux_stack() is not NMU safe and must be avoided. - Using TWA_RESUME is NMI safe. If the NMI occurs while the CPU is in userland then it will continue in userland and not invoke the `work' callback. Add TWA_NMI_CURRENT as an additional notify mode. In this mode skip kasan and use irq_work in hardirq-mode to for needed interrupt. Set TIF_NOTIFY_RESUME within the irq_work callback due to k[ac]san instrumentation in test_and_set_bit() which does not look NMI safe in case of a report. Suggested-by: Peter Zijlstra Signed-off-by: Sebastian Andrzej Siewior --- include/linux/task_work.h | 1 + kernel/task_work.c | 25 ++++++++++++++++++++++--- 2 files changed, 23 insertions(+), 3 deletions(-) diff --git a/include/linux/task_work.h b/include/linux/task_work.h index 26b8a47f41fca..cf5e7e891a776 100644 --- a/include/linux/task_work.h +++ b/include/linux/task_work.h @@ -18,6 +18,7 @@ enum task_work_notify_mode { TWA_RESUME, TWA_SIGNAL, TWA_SIGNAL_NO_IPI, + TWA_NMI_CURRENT, }; =20 static inline bool task_work_pending(struct task_struct *task) diff --git a/kernel/task_work.c b/kernel/task_work.c index 2134ac8057a94..05fb41fe09f5d 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -1,10 +1,19 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include +#include =20 static struct callback_head work_exited; /* all we need is ->next =3D=3D N= ULL */ =20 +static void task_work_set_notify_irq(struct irq_work *entry) +{ + test_and_set_tsk_thread_flag(current, TIF_NOTIFY_RESUME); +} +static DEFINE_PER_CPU(struct irq_work, irq_work_NMI_resume) =3D + IRQ_WORK_INIT_HARD(task_work_set_notify_irq); + /** * task_work_add - ask the @task to execute @work->func() * @task: the task which should run the callback @@ -12,7 +21,7 @@ static struct callback_head work_exited; /* all we need i= s ->next =3D=3D NULL */ * @notify: how to notify the targeted task * * Queue @work for task_work_run() below and notify the @task if @notify - * is @TWA_RESUME, @TWA_SIGNAL, or @TWA_SIGNAL_NO_IPI. + * is @TWA_RESUME, @TWA_SIGNAL, @TWA_SIGNAL_NO_IPI or @TWA_NMI_CURRENT. * * @TWA_SIGNAL works like signals, in that the it will interrupt the targe= ted * task and run the task_work, regardless of whether the task is currently @@ -24,6 +33,8 @@ static struct callback_head work_exited; /* all we need i= s ->next =3D=3D NULL */ * kernel anyway. * @TWA_RESUME work is run only when the task exits the kernel and returns= to * user mode, or before entering guest mode. + * @TWA_NMI_CURRENT works like @TWA_RESUME, except it can only be used for= the + * current @task and if the current context is NMI. * * Fails if the @task is exiting/exited and thus it can't process this @wo= rk. * Otherwise @work->func() will be called when the @task goes through one = of @@ -44,8 +55,13 @@ int task_work_add(struct task_struct *task, struct callb= ack_head *work, { struct callback_head *head; =20 - /* record the work call stack in order to print it in KASAN reports */ - kasan_record_aux_stack(work); + if (notify =3D=3D TWA_NMI_CURRENT) { + if (WARN_ON_ONCE(task !=3D current)) + return -EINVAL; + } else { + /* record the work call stack in order to print it in KASAN reports */ + kasan_record_aux_stack(work); + } =20 head =3D READ_ONCE(task->task_works); do { @@ -66,6 +82,9 @@ int task_work_add(struct task_struct *task, struct callba= ck_head *work, case TWA_SIGNAL_NO_IPI: __set_notify_signal(task); break; + case TWA_NMI_CURRENT: + irq_work_queue(this_cpu_ptr(&irq_work_NMI_resume)); + break; default: WARN_ON_ONCE(1); break; --=20 2.45.2