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Commit 65f382fd authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

context_tracking: Ground setup for static key use 



Prepare for using a static key in the context tracking subsystem.
This will help optimizing the off case on its many users:

* user_enter, user_exit, exception_enter, exception_exit, guest_enter,
  guest_exit, vtime_*()

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
parent d84d27a4

include/linux/context_tracking.h

+10 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/sched.h>

#include <linux/percpu.h>

#include <linux/vtime.h>

#include <linux/static_key.h>

#include <asm/ptrace.h>



struct context_tracking {
@@ -22,6 +23,7 @@ struct context_tracking { 




#ifdef CONFIG_CONTEXT_TRACKING

extern struct static_key context_tracking_enabled;

DECLARE_PER_CPU(struct context_tracking, context_tracking);



static inline bool context_tracking_in_user(void)
@@ -67,6 +69,14 @@ static inline void context_tracking_task_switch(struct task_struct *prev, 
						struct task_struct *next) { }

#endif /* !CONFIG_CONTEXT_TRACKING */





#ifdef CONFIG_CONTEXT_TRACKING_FORCE

extern void context_tracking_init(void);

#else

static inline void context_tracking_init(void) { }

#endif /* CONFIG_CONTEXT_TRACKING_FORCE */





#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN

extern void guest_enter(void);

extern void guest_exit(void);

init/main.c

+2 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ 
#include <linux/blkdev.h>

#include <linux/elevator.h>

#include <linux/sched_clock.h>

#include <linux/context_tracking.h>



#include <asm/io.h>

#include <asm/bugs.h>
@@ -545,6 +546,7 @@ asmlinkage void __init start_kernel(void) 
	idr_init_cache();

	rcu_init();

	tick_nohz_init();

	context_tracking_init();

	radix_tree_init();

	/* init some links before init_ISA_irqs() */

	early_irq_init();

kernel/context_tracking.c

+17 −6
Original line number Diff line number Diff line
@@ -20,15 +20,16 @@ 
#include <linux/hardirq.h>

#include <linux/export.h>



DEFINE_PER_CPU(struct context_tracking, context_tracking) = {

#ifdef CONFIG_CONTEXT_TRACKING_FORCE

	.active = true,

#endif

};

struct static_key context_tracking_enabled = STATIC_KEY_INIT_FALSE;



DEFINE_PER_CPU(struct context_tracking, context_tracking);



void context_tracking_cpu_set(int cpu)

{

	if (!per_cpu(context_tracking.active, cpu)) {

		per_cpu(context_tracking.active, cpu) = true;

		static_key_slow_inc(&context_tracking_enabled);

	}

}



/**
@@ -202,3 +203,13 @@ void context_tracking_task_switch(struct task_struct *prev, 
	clear_tsk_thread_flag(prev, TIF_NOHZ);

	set_tsk_thread_flag(next, TIF_NOHZ);

}



#ifdef CONFIG_CONTEXT_TRACKING_FORCE

void __init context_tracking_init(void)

{

	int cpu;



	for_each_possible_cpu(cpu)

		context_tracking_cpu_set(cpu);

}

#endif