linux-kernel - [PATCH RFC 05/12] entry/idle: Enter and exit kernel protection during idle entry and exit

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Date:   Fri, 14 Aug 2020 23:19:01 -0400
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Kees Cook <keescook@...omium.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Paul Turner <pjt@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tim Chen <tim.c.chen@...el.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        fweisbec@...il.com, kerrnel@...gle.com,
        Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>
Subject: [PATCH RFC 05/12] entry/idle: Enter and exit kernel protection during idle entry and exit

Make use of the generic_idle_{enter,exit} helper function added in
earlier patches to enter and exit kernel protection.

On exiting idle, protection will be reenabled.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 include/linux/entry-common.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
index 2ea0e09b00d5..c833f2fda542 100644
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -374,6 +374,9 @@ void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
  */
 static inline void generic_idle_enter(void)
 {
+	/* Entering idle ends the protected kernel region. */
+	sched_core_unsafe_exit();
+
 	rcu_idle_enter();
 }
 
@@ -383,6 +386,9 @@ static inline void generic_idle_enter(void)
 static inline void generic_idle_exit(void)
 {
 	rcu_idle_exit();
+
+	/* Exiting idle (re)starts the protected kernel region. */
+	sched_core_unsafe_enter();
 }
 
 #endif
-- 
2.28.0.220.ged08abb693-goog