Commit 493c1822 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Paul E. McKenney
Browse files

context_tracking: Take NMI eqs entrypoints over RCU 



The RCU dynticks counter is going to be merged into the context tracking
subsystem. Prepare with moving the NMI extended quiescent states
entrypoints to context tracking. For now those are dumb redirection to
existing RCU calls.

Acked-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarNicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: default avatarNicolas Saenz Julienne <nsaenzju@redhat.com>
parent 6f0e6c15

Documentation/RCU/Design/Requirements/Requirements.rst

+1 −1
Original line number Diff line number Diff line
@@ -1847,7 +1847,7 @@ normal interrupts. One way that this can happen is for code that 
directly invokes ct_irq_enter() and ct_irq_exit() to be called

from an NMI handler. This astonishing fact of life prompted the current

code structure, which has ct_irq_enter() invoking

rcu_nmi_enter() and ct_irq_exit() invoking rcu_nmi_exit().

ct_nmi_enter() and ct_irq_exit() invoking ct_nmi_exit().

And yes, I also learned of this requirement the hard way.



Loadable Modules

arch/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -797,7 +797,7 @@ config HAVE_CONTEXT_TRACKING_USER_OFFSTACK 


	  - Critical entry code isn't preemptible (or better yet:

	    not interruptible).

	  - No use of RCU read side critical sections, unless rcu_nmi_enter()

	  - No use of RCU read side critical sections, unless ct_nmi_enter()

	    got called.

	  - No use of instrumentation, unless instrumentation_begin() got

	    called.

arch/arm64/kernel/entry-common.c

+4 −4
Original line number Diff line number Diff line
@@ -161,7 +161,7 @@ static void noinstr arm64_enter_nmi(struct pt_regs *regs) 
	__nmi_enter();

	lockdep_hardirqs_off(CALLER_ADDR0);

	lockdep_hardirq_enter();

	rcu_nmi_enter();

	ct_nmi_enter();



	trace_hardirqs_off_finish();

	ftrace_nmi_enter();
@@ -182,7 +182,7 @@ static void noinstr arm64_exit_nmi(struct pt_regs *regs) 
		lockdep_hardirqs_on_prepare();

	}



	rcu_nmi_exit();

	ct_nmi_exit();

	lockdep_hardirq_exit();

	if (restore)

		lockdep_hardirqs_on(CALLER_ADDR0);
@@ -199,7 +199,7 @@ static void noinstr arm64_enter_el1_dbg(struct pt_regs *regs) 
	regs->lockdep_hardirqs = lockdep_hardirqs_enabled();



	lockdep_hardirqs_off(CALLER_ADDR0);

	rcu_nmi_enter();

	ct_nmi_enter();



	trace_hardirqs_off_finish();

}
@@ -218,7 +218,7 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs) 
		lockdep_hardirqs_on_prepare();

	}



	rcu_nmi_exit();

	ct_nmi_exit();

	if (restore)

		lockdep_hardirqs_on(CALLER_ADDR0);

}

include/linux/context_tracking_irq.h

+4 −0
Original line number Diff line number Diff line
@@ -7,11 +7,15 @@ void ct_irq_enter(void); 
void ct_irq_exit(void);

void ct_irq_enter_irqson(void);

void ct_irq_exit_irqson(void);

void ct_nmi_enter(void);

void ct_nmi_exit(void);

#else

static inline void ct_irq_enter(void) { }

static inline void ct_irq_exit(void) { }

static inline void ct_irq_enter_irqson(void) { }

static inline void ct_irq_exit_irqson(void) { }

static inline void ct_nmi_enter(void) { }

static inline void ct_nmi_exit(void) { }

#endif



#endif

include/linux/hardirq.h

+2 −2
Original line number Diff line number Diff line
@@ -124,7 +124,7 @@ extern void rcu_nmi_exit(void); 
	do {							\

		__nmi_enter();					\

		lockdep_hardirq_enter();			\

		rcu_nmi_enter();				\

		ct_nmi_enter();				\

		instrumentation_begin();			\

		ftrace_nmi_enter();				\

		instrumentation_end();				\
@@ -143,7 +143,7 @@ extern void rcu_nmi_exit(void); 
		instrumentation_begin();			\

		ftrace_nmi_exit();				\

		instrumentation_end();				\

		rcu_nmi_exit();					\

		ct_nmi_exit();					\

		lockdep_hardirq_exit();				\

		__nmi_exit();					\

	} while (0)