From nobody Thu Nov 28 08:32:41 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 CDDEE1A2C32; Thu, 3 Oct 2024 15:18:49 +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=1727968733; cv=none; b=uIzWSrPFltPa7DLTk136GhoAZs/+w4TmAeG6kpwUkKXY69stX23i/HUfIEeWuEkjiAcaA/zhEyB89H07L29bS4flGOFKuzpWW6yo5L0tDKRgaViMOoBa+XDgSXhqXUS9gzBz/bOSoXZ0BtKj7yozIdwKmGi3ffy+UqJO6rwaHSI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727968733; c=relaxed/simple; bh=cFKaryhx8iL3A0KR0AkdZdd7ZsIGBNvmJeXwPGSJJBE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=AZNaTIhD6sKF65IP68xMEdZ6Syz5O0BN/aJavqHwkCo+bmzBwwE9758ycMtzSNy7Tm59zFewafmsJMwJ/CV5sZEOv063fgrtt3X1u2xfrkdeNMg4W2tiuzgQ2kykp4FzddtsazcWJ6YwIrCMzxKFZacUjZnXN1CtCsf+wSddVCE= 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=ba7jj/3k; 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="ba7jj/3k" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1727968725; bh=cFKaryhx8iL3A0KR0AkdZdd7ZsIGBNvmJeXwPGSJJBE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ba7jj/3kHWelvv8zFIa0KiKXxkHJoQSR8ucgpInmUSXf1Ddq3iHqFe/ylEeBA2B59 JL0juShEwPw7iLpsYPQQCEAoohnReLjCelQ0mAjOQ/jUn0x9kK5Re3ZHZmD0n5uhGG ELM1iqbb+lAcDIzUnS+IAgewwdMMU8v3Lpy27Q23gIgEc1VnprQDoyhzEz7jM2iu7Y LbuYDIhqyOa88gen751+RbBgYY/fMX5W3mLE8uUeGaXyTyoX2RJcpKD08OCmoU51/z gZ3jjipHklwwbED1/hkxcL13lQ52HCkMrEOIhTJCoxUz8mHPAPRoQqr3Dxm4j2eSTY wTrIvxv706lKQ== 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 4XKFgm5G4rz5pT; Thu, 3 Oct 2024 11:18:44 -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 v1 5/8] tracing: Allow system call tracepoints to handle page faults Date: Thu, 3 Oct 2024 11:16:35 -0400 Message-Id: <20241003151638.1608537-6-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20241003151638.1608537-1-mathieu.desnoyers@efficios.com> References: <20241003151638.1608537-1-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 666499b9f3be..6faf34e5efc9 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -17,6 +17,7 @@ #include #include #include +#include #include #include =20 @@ -109,6 +110,7 @@ void for_each_tracepoint_in_module(struct module *mod, #ifdef CONFIG_TRACEPOINTS static inline void tracepoint_synchronize_unregister(void) { + synchronize_rcu_tasks_trace(); synchronize_srcu(&tracepoint_srcu); synchronize_rcu(); } @@ -211,7 +213,7 @@ 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; \ \ @@ -222,8 +224,12 @@ 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 \ @@ -241,7 +247,10 @@ 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 @@ -251,7 +260,7 @@ 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) @@ -284,7 +293,7 @@ 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"); \ @@ -295,7 +304,7 @@ 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) \ @@ -330,7 +339,7 @@ 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 fbd0cb06a50a..eedd0064fb36 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1984,6 +1984,7 @@ config BINDGEN_VERSION_TEXT # config TRACEPOINTS bool + select TASKS_TRACE_RCU =20 source "kernel/Kconfig.kexec" =20 --=20 2.39.2