linux-kernel - [PATCH RFC tip/core/rcu] Make rcu_irq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 22 Sep 2017 13:14:00 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     rostedt@...dmis.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH RFC tip/core/rcu] Make rcu_irq_{enter,exit} check for NMI

Hello, Steve,

Yet another attempt to allow safe initiation of RCU voyeurism...

Untested at the moment.

							Thanx, Paul

------------------------------------------------------------------------

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index db5eb8c3f7af..872d20cee00a 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -891,6 +891,11 @@ void rcu_irq_exit(void)
 
 	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs enabled!!!");
 	rdtp = this_cpu_ptr(&rcu_dynticks);
+
+	/* Page faults can happen in NMI handlers, so check... */
+	if (READ_ONCE(rdtp->dynticks_nmi_nesting))
+		return;
+
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
 		     rdtp->dynticks_nesting < 1);
 	if (rdtp->dynticks_nesting <= 1) {
@@ -1036,6 +1041,11 @@ void rcu_irq_enter(void)
 
 	RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_enter() invoked with irqs enabled!!!");
 	rdtp = this_cpu_ptr(&rcu_dynticks);
+
+	/* Page faults can happen in NMI handlers, so check... */
+	if (READ_ONCE(rdtp->dynticks_nmi_nesting))
+		return;
+
 	oldval = rdtp->dynticks_nesting;
 	rdtp->dynticks_nesting++;
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&