Commit 3d33345a authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Martin Schwidefsky
Browse files

s390/cpum_cf: prepare for in-kernel counter measurements 



Prepare the counter facility support to be used by other in-kernel
users.  The first step introduces the __kernel_cpumcf_begin() and
__kernel_cpumcf_end() functions to reserve the counter facility
for doing measurements and to release after the measurements are
done.

Signed-off-by: default avatarHendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 30e145f8

arch/s390/include/asm/cpu_mcf.h

+3 −0
Original line number Diff line number Diff line
@@ -49,4 +49,7 @@ static inline void ctr_set_stop(u64 *state, int ctr_set) 
	*state &= ~(cpumf_ctr_ctl[ctr_set] << CPUMF_LCCTL_ACTCTL_SHIFT);

}



int __kernel_cpumcf_begin(void);

void __kernel_cpumcf_end(void);



#endif /* _ASM_S390_CPU_MCF_H */

arch/s390/kernel/perf_cpum_cf.c

+26 −6
Original line number Diff line number Diff line
@@ -236,25 +236,45 @@ static void setup_pmc_cpu(void *flags) 
	lcctl(0);

}



/* Initialize the CPU-measurement facility */

static int reserve_pmc_hardware(void)

/* Reserve/release functions for sharing perf hardware */

static DEFINE_SPINLOCK(cpumcf_owner_lock);

static void *cpumcf_owner;



/* Initialize the CPU-measurement counter facility */

int __kernel_cpumcf_begin(void)

{

	int flags = PMC_INIT;

	int err = 0;



	spin_lock(&cpumcf_owner_lock);

	if (cpumcf_owner)

		err = -EBUSY;

	else

		cpumcf_owner = __builtin_return_address(0);

	spin_unlock(&cpumcf_owner_lock);

	if (err)

		return err;



	on_each_cpu(setup_pmc_cpu, &flags, 1);

	irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);



	return 0;

}

EXPORT_SYMBOL(__kernel_cpumcf_begin);



/* Release the CPU-measurement facility */

static void release_pmc_hardware(void)

/* Release the CPU-measurement counter facility */

void __kernel_cpumcf_end(void)

{

	int flags = PMC_RELEASE;



	on_each_cpu(setup_pmc_cpu, &flags, 1);

	irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);



	spin_lock(&cpumcf_owner_lock);

	cpumcf_owner = NULL;

	spin_unlock(&cpumcf_owner_lock);

}

EXPORT_SYMBOL(__kernel_cpumcf_end);



/* Release the PMU if event is the last perf event */

static void hw_perf_event_destroy(struct perf_event *event)
@@ -262,7 +282,7 @@ static void hw_perf_event_destroy(struct perf_event *event) 
	if (!atomic_add_unless(&num_events, -1, 1)) {

		mutex_lock(&pmc_reserve_mutex);

		if (atomic_dec_return(&num_events) == 0)

			release_pmc_hardware();

			__kernel_cpumcf_end();

		mutex_unlock(&pmc_reserve_mutex);

	}

}
@@ -363,7 +383,7 @@ static int __hw_perf_event_init(struct perf_event *event) 
	/* Initialize for using the CPU-measurement counter facility */

	if (!atomic_inc_not_zero(&num_events)) {

		mutex_lock(&pmc_reserve_mutex);

		if (atomic_read(&num_events) == 0 && reserve_pmc_hardware())

		if (atomic_read(&num_events) == 0 && __kernel_cpumcf_begin())

			err = -EBUSY;

		else

			atomic_inc(&num_events);