From nobody Wed Dec 17 15:34:27 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 1F049158DD9; Tue, 9 Jul 2024 11:42:01 +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=1720525323; cv=none; b=WeKMICdoI3KRc3jGQc7Rr2PxxWEtSJXoafKcEiAY7Eb7XtP9XCVzEcq29BKBurstX4XlFjWB9+r3Kd9ORwNq2kVZGWa7UBe43IgOQel6oJTX8IbCsiYcZI283jXn2Rqer1SMlVkKIlKC2yMXXThSZb/j0GtgTbnVPOr7Pds4rec= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720525323; c=relaxed/simple; bh=/fAT3MGOTSy0nq4WLdKJEl2sqdwHOsx2BdkaTu49WLA=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=j6oNLSXgoJzr6lOaTyBTin0ra9mhyoKQhzWKUhgzv/m7M+aaFvbw78L1qLaIs42tN04BYV+4tSrTp4TQyWJZL/rpi4I3zkzqGOKrTgNf05749H1v5z1fbu0PwST6UX1ul+j6qvH+DFZXqaPMOUZC4pTjmQ86NzpACCYAaOrhNSo= 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=XC3/uLPn; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Kljxqvz5; 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="XC3/uLPn"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Kljxqvz5" Date: Tue, 09 Jul 2024 11:41:59 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1720525319; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9g4MHJODxuiymtPq3xlHv+SjAEhWu2ul+C8d0CXIy14=; b=XC3/uLPnaWYQyffAQex14jD4Zc+TlVrno8HQafiYktqysHbjb4AxOm1uDCqCZYRinIwhh6 sfCi0RFSnBaZTTYxTWcu6YyJtc6rHrEX7Qcf7QEwcjQQCi5z51PevAE3g7swwTAgaWHUuo WAbgFMM+ZoXA6TxtYnyrjtr/klFXa8d0bCyaBxwJGuuaStzSHpYLAqoABRJKZW7dgI6ojY 2Mc8KULx2HWOicyexcu4TptGhZ9Zt8BJA3rOAekaPErbg59CO2ZO7EYsw4yC28AQCMw5aL 0DLwGKhVzHXKdDkBejc+RCqgQgkV3GnRo5T4UFXEKLNs+ajXaynXASdvfDYKSw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1720525319; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9g4MHJODxuiymtPq3xlHv+SjAEhWu2ul+C8d0CXIy14=; b=Kljxqvz5mKPuVVuG1KKG1J1DBGmUewrFtTkMFTfmvPN5LWvsJsICHlFaL83B0utr0vOLSv aSD+pxJFbWfeU1Aw== From: "tip-bot2 for Sebastian Andrzej Siewior" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/core] task_work: Add TWA_NMI_CURRENT as an additional notify mode. Cc: Peter Zijlstra , Sebastian Andrzej Siewior , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20240704170424.1466941-3-bigeasy@linutronix.de> References: <20240704170424.1466941-3-bigeasy@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <172052531910.2215.8236126764601999778.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the perf/core branch of tip: Commit-ID: 466e4d801cd438a1ab2c8a2cce1bef6b65c31bbb Gitweb: https://git.kernel.org/tip/466e4d801cd438a1ab2c8a2cce1bef6b6= 5c31bbb Author: Sebastian Andrzej Siewior AuthorDate: Thu, 04 Jul 2024 19:03:36 +02:00 Committer: Peter Zijlstra CommitterDate: Tue, 09 Jul 2024 13:26:34 +02:00 task_work: Add TWA_NMI_CURRENT as an additional notify mode. 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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20240704170424.1466941-3-bigeasy@linutronix= .de --- include/linux/task_work.h | 1 + kernel/task_work.c | 24 +++++++++++++++++++++--- 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/include/linux/task_work.h b/include/linux/task_work.h index 26b8a47..cf5e7e8 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 2134ac8..5c2daa7 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -1,10 +1,18 @@ // SPDX-License-Identifier: GPL-2.0 +#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 +20,7 @@ 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 +32,8 @@ 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 +54,13 @@ 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 +81,9 @@ 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;