From nobody Thu Nov 28 20:07:12 2024 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) (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 AD01919A288; Mon, 30 Sep 2024 19:26:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=167.114.26.122 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727724396; cv=none; b=g3SzjAtV9I7lEYVwtEVxSvyGHpz6T/J7wEv1Q3KCZqb/v4ywIrlf3oNQub0gHrdL6EX9AIDqPRyUUqOBLjawgPyL+/cxKQJZJ/xi92gdx2SYL8FxOUfxDcDka9fMJG9APXrWKCWG2OGkTH1H1JwL3867GItXz7o/aE+g0ROQVlk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727724396; c=relaxed/simple; bh=YAvfsUVzkdfENSEXcdox6M3fVrWGL98jFGGUdZ3uQlo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=hh+9y4ywSXXaDWaf65QD38WJAyPyys94+SB6OqB0dqBuT/k8Aq9QsY/M5I4HvwHvNvYpZIuTMDyke/Nn/1Hn96eFwHIBmDnhgxsBCja/5Q1wrUojcUL7cbf09f2GyAcStSidu1DonxGrkJXSBlNF6ffafAkKei08/iEuxf/3Bw4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=u6Ekf46q; arc=none smtp.client-ip=167.114.26.122 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="u6Ekf46q" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1727724392; bh=YAvfsUVzkdfENSEXcdox6M3fVrWGL98jFGGUdZ3uQlo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u6Ekf46qlP8Twrz9HI8S9JwYn0vP6FGn3guxZNAp5YoGh1deUucH86mPWQriTIfPC 3TxQkudaY4TwWja926DGvuaPSOLk6pXCis3uX1dNCxNtKwRFAIal9ZjSP/jfbwkKtc L6UiCnn5qLXSPhTZrdcZee+WfRBbxgucGiYkroACYKMzqAUYlN+Nr80mKofaXknFwt EWy02iiuXbUv2EVxNpOJqxbPG0HXGs7yvymIVBsakk32ugKxixOo77KXyjqK3sfIBu lO2ocXBxRlQix8MD/W8zRjSw7FZpXzCkSYzreqobA5/lQaLdM05qSx1mSCVp0QSkau 0PwR+5IpE0+pA== Received: from thinkos.internal.efficios.com (96-127-217-162.qc.cable.ebox.net [96.127.217.162]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4XHWK41kL0zQPl; Mon, 30 Sep 2024 15:26:32 -0400 (EDT) From: Mathieu Desnoyers To: Steven Rostedt , Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, Mathieu Desnoyers , Peter Zijlstra , Alexei Starovoitov , Yonghong Song , "Paul E . McKenney" , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Namhyung Kim , Andrii Nakryiko , bpf@vger.kernel.org, Joel Fernandes , linux-trace-kernel@vger.kernel.org, Michael Jeanson Subject: [PATCH resend 5/8] tracing: Allow system call tracepoints to handle page faults Date: Mon, 30 Sep 2024 15:23:54 -0400 Message-Id: <20240930192357.1154417-6-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240930192357.1154417-1-mathieu.desnoyers@efficios.com> References: <20240930192357.1154417-1-mathieu.desnoyers@efficios.com> 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" Use Tasks Trace RCU to protect iteration of system call enter/exit tracepoint probes to allow those probes to handle page faults. In preparation for this change, all tracers registering to system call enter/exit tracepoints should expect those to be called with preemption enabled. This allows tracers to fault-in userspace system call arguments such as path strings within their probe callbacks. Signed-off-by: Mathieu Desnoyers Cc: Michael Jeanson Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Alexei Starovoitov Cc: Yonghong Song Cc: Paul E. McKenney Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Mark Rutland Cc: Alexander Shishkin Cc: Namhyung Kim Cc: Andrii Nakryiko Cc: bpf@vger.kernel.org Cc: Joel Fernandes --- include/linux/tracepoint.h | 25 +++++++++++++++++-------- init/Kconfig | 1 + 2 files changed, 18 insertions(+), 8 deletions(-) diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 2e4b4952bba2..106e951896c2 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -17,6 +17,7 @@ #include #include #include +#include #include #include =20 @@ -89,6 +90,7 @@ int unregister_tracepoint_module_notifier(struct notifier= _block *nb) #ifdef CONFIG_TRACEPOINTS static inline void tracepoint_synchronize_unregister(void) { + synchronize_rcu_tasks_trace(); synchronize_srcu(&tracepoint_srcu); synchronize_rcu(); } @@ -191,7 +193,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(t= racepoint_ptr_t *p) * it_func[0] is never NULL because there is at least one element in the a= rray * when the array itself is non NULL. */ -#define __DO_TRACE(name, args, cond, rcuidle) \ +#define __DO_TRACE(name, args, cond, rcuidle, syscall) \ do { \ int __maybe_unused __idx =3D 0; \ \ @@ -202,8 +204,12 @@ static inline struct tracepoint *tracepoint_ptr_deref(= tracepoint_ptr_t *p) "Bad RCU usage for tracepoint")) \ return; \ \ - /* keep srcu and sched-rcu usage consistent */ \ - preempt_disable_notrace(); \ + if (syscall) { \ + rcu_read_lock_trace(); \ + } else { \ + /* keep srcu and sched-rcu usage consistent */ \ + preempt_disable_notrace(); \ + } \ \ /* \ * For rcuidle callers, use srcu since sched-rcu \ @@ -221,7 +227,10 @@ static inline struct tracepoint *tracepoint_ptr_deref(= tracepoint_ptr_t *p) srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\ } \ \ - preempt_enable_notrace(); \ + if (syscall) \ + rcu_read_unlock_trace(); \ + else \ + preempt_enable_notrace(); \ } while (0) =20 #ifndef MODULE @@ -231,7 +240,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(t= racepoint_ptr_t *p) if (static_key_false(&__tracepoint_##name.key)) \ __DO_TRACE(name, \ TP_ARGS(args), \ - TP_CONDITION(cond), 1); \ + TP_CONDITION(cond), 1, 0); \ } #else #define __DECLARE_TRACE_RCU(name, proto, args, cond) @@ -275,7 +284,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(t= racepoint_ptr_t *p) if (static_key_false(&__tracepoint_##name.key)) \ __DO_TRACE(name, \ TP_ARGS(args), \ - TP_CONDITION(cond), 0); \ + TP_CONDITION(cond), 0, 0); \ if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ WARN_ONCE(!rcu_is_watching(), \ "RCU not watching for tracepoint"); \ @@ -286,7 +295,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(t= racepoint_ptr_t *p) if (static_key_false(&__tracepoint_##name.key)) \ __DO_TRACE(name, \ TP_ARGS(args), \ - TP_CONDITION(cond), 1); \ + TP_CONDITION(cond), 1, 0); \ } \ static inline int \ register_trace_##name(void (*probe)(data_proto), void *data) \ @@ -309,7 +318,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(t= racepoint_ptr_t *p) if (static_key_false(&__tracepoint_##name.key)) \ __DO_TRACE(name, \ TP_ARGS(args), \ - TP_CONDITION(cond), 0); \ + TP_CONDITION(cond), 0, 1); \ if (IS_ENABLED(CONFIG_LOCKDEP) && (cond)) { \ WARN_ONCE(!rcu_is_watching(), \ "RCU not watching for tracepoint"); \ diff --git a/init/Kconfig b/init/Kconfig index 5783a0b87517..72e13ee73c43 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1936,6 +1936,7 @@ config BINDGEN_VERSION_TEXT # config TRACEPOINTS bool + select TASKS_TRACE_RCU =20 source "kernel/Kconfig.kexec" =20 --=20 2.39.2