Documentation/perf_counter/perfcounters.h

/*
 * Ioctls that can be done on a perf counter fd:
 */
#define PERF_COUNTER_IOC_ENABLE		_IO('$', 0)
#define PERF_COUNTER_IOC_DISABLE	_IO('$', 1)

/*
 * prctl(PR_TASK_PERF_COUNTERS_DISABLE) will (cheaply) disable all
 * counters in the current task.
 */
#define PR_TASK_PERF_COUNTERS_DISABLE	31
#define PR_TASK_PERF_COUNTERS_ENABLE    32

#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))

#define rdclock()					\
({							\
	struct timespec ts;				\
							\
	clock_gettime(CLOCK_MONOTONIC, &ts);		\
	ts.tv_sec * 1000000000ULL + ts.tv_nsec;		\
})

/*
 * Pick up some kernel type conventions:
 */
#define __user
#define asmlinkage

typedef unsigned int		__u32;
typedef unsigned long long	__u64;
typedef long long		__s64;

/*
 * User-space ABI bits:
 */

/*
 * Generalized performance counter event types, used by the hw_event.type
 * parameter of the sys_perf_counter_open() syscall:
 */
enum hw_event_types {
	/*
	 * Common hardware events, generalized by the kernel:
	 */
	PERF_COUNT_CPU_CYCLES		=  0,
	PERF_COUNT_INSTRUCTIONS		=  1,
	PERF_COUNT_CACHE_REFERENCES	=  2,
	PERF_COUNT_CACHE_MISSES		=  3,
	PERF_COUNT_BRANCH_INSTRUCTIONS	=  4,
	PERF_COUNT_BRANCH_MISSES	=  5,
	PERF_COUNT_BUS_CYCLES		=  6,

	PERF_HW_EVENTS_MAX		=  7,

	/*
	 * Special "software" counters provided by the kernel, even if
	 * the hardware does not support performance counters. These
	 * counters measure various physical and sw events of the
	 * kernel (and allow the profiling of them as well):
	 */
	PERF_COUNT_CPU_CLOCK		= -1,
	PERF_COUNT_TASK_CLOCK		= -2,
	PERF_COUNT_PAGE_FAULTS		= -3,
	PERF_COUNT_CONTEXT_SWITCHES	= -4,
	PERF_COUNT_CPU_MIGRATIONS	= -5,

	PERF_SW_EVENTS_MIN		= -6,
};

/*
 * IRQ-notification data record type:
 */
enum perf_counter_record_type {
	PERF_RECORD_SIMPLE		=  0,
	PERF_RECORD_IRQ			=  1,
	PERF_RECORD_GROUP		=  2,
};

/*
 * Hardware event to monitor via a performance monitoring counter:
 */
struct perf_counter_hw_event {
	__s64			type;

	__u64			irq_period;
	__u64			record_type;
	__u64			read_format;

	__u64			disabled       :  1, /* off by default        */
				nmi	       :  1, /* NMI sampling          */
				raw	       :  1, /* raw event type        */
				inherit	       :  1, /* children inherit it   */
				pinned	       :  1, /* must always be on PMU */
				exclusive      :  1, /* only group on PMU     */
				exclude_user   :  1, /* don't count user      */
				exclude_kernel :  1, /* ditto kernel          */
				exclude_hv     :  1, /* ditto hypervisor      */
				exclude_idle   :  1, /* don't count when idle */

				__reserved_1   : 54;

	__u32			extra_config_len;
	__u32			__reserved_4;

	__u64			__reserved_2;
	__u64			__reserved_3;
};


#ifdef __x86_64__
# define __NR_perf_counter_open	295
#endif

#ifdef __i386__
# define __NR_perf_counter_open 333
#endif

#ifdef __powerpc__
#define __NR_perf_counter_open 319
#endif

asmlinkage int sys_perf_counter_open(

	struct perf_counter_hw_event	*hw_event_uptr		__user,
	pid_t				pid,
	int				cpu,
	int				group_fd,
	unsigned long			flags)
{
	int ret;

	ret = syscall(
		__NR_perf_counter_open, hw_event_uptr, pid, cpu, group_fd, flags);
#if defined(__x86_64__) || defined(__i386__)
	if (ret < 0 && ret > -4096) {
		errno = -ret;
		ret = -1;
	}
#endif
	return ret;
}