linux/kernel/events/internal.h

#ifndef _KERNEL_EVENTS_INTERNAL_H
#define _KERNEL_EVENTS_INTERNAL_H

#include <linux/hardirq.h>
#include <linux/uaccess.h>

/* Buffer handling */

#define RING_BUFFER_WRITABLE		0x01

struct ring_buffer {
	atomic_t			refcount;
	struct rcu_head			rcu_head;
#ifdef CONFIG_PERF_USE_VMALLOC
	struct work_struct		work;
	int				page_order;	/* allocation order  */
#endif
	int				nr_pages;	/* nr of data pages  */
	int				writable;	/* are we writable   */

	atomic_t			poll;		/* POLL_ for wakeups */

	local_t				head;		/* write position    */
	local_t				nest;		/* nested writers    */
	local_t				events;		/* event limit       */
	local_t				wakeup;		/* wakeup stamp      */
	local_t				lost;		/* nr records lost   */

	long				watermark;	/* wakeup watermark  */
	/* poll crap */
	spinlock_t			event_lock;
	struct list_head		event_list;

	struct perf_event_mmap_page	*user_page;
	void				*data_pages[0];
};

extern void rb_free(struct ring_buffer *rb);
extern struct ring_buffer *
rb_alloc(int nr_pages, long watermark, int cpu, int flags);
extern void perf_event_wakeup(struct perf_event *event);

extern void
perf_event_header__init_id(struct perf_event_header *header,
			   struct perf_sample_data *data,
			   struct perf_event *event);
extern void
perf_event__output_id_sample(struct perf_event *event,
			     struct perf_output_handle *handle,
			     struct perf_sample_data *sample);

extern struct page *
perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff);

#ifdef CONFIG_PERF_USE_VMALLOC
/*
 * Back perf_mmap() with vmalloc memory.
 *
 * Required for architectures that have d-cache aliasing issues.
 */

static inline int page_order(struct ring_buffer *rb)
{
	return rb->page_order;
}

#else

static inline int page_order(struct ring_buffer *rb)
{
	return 0;
}
#endif

static inline unsigned long perf_data_size(struct ring_buffer *rb)
{
	return rb->nr_pages << (PAGE_SHIFT + page_order(rb));
}

#define DEFINE_OUTPUT_COPY(func_name, memcpy_func)			\
static inline unsigned int						\
func_name(struct perf_output_handle *handle,				\
	  const void *buf, unsigned int len)				\
{									\
	unsigned long size, written;					\
									\
	do {								\
		size = min_t(unsigned long, handle->size, len);		\
									\
		written = memcpy_func(handle->addr, buf, size);		\
									\
		len -= written;						\
		handle->addr += written;				\
		buf += written;						\
		handle->size -= written;				\
		if (!handle->size) {					\
			struct ring_buffer *rb = handle->rb;		\
									\
			handle->page++;					\
			handle->page &= rb->nr_pages - 1;		\
			handle->addr = rb->data_pages[handle->page];	\
			handle->size = PAGE_SIZE << page_order(rb);	\
		}							\
	} while (len && written == size);				\
									\
	return len;							\
}

static inline int memcpy_common(void *dst, const void *src, size_t n)
{
	memcpy(dst, src, n);
	return n;
}

DEFINE_OUTPUT_COPY(__output_copy, memcpy_common)

#define MEMCPY_SKIP(dst, src, n) (n)

DEFINE_OUTPUT_COPY(__output_skip, MEMCPY_SKIP)

#ifndef arch_perf_out_copy_user
#define arch_perf_out_copy_user __copy_from_user_inatomic
#endif

DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)

/* Callchain handling */
extern struct perf_callchain_entry *
perf_callchain(struct perf_event *event, struct pt_regs *regs);
extern int get_callchain_buffers(void);
extern void put_callchain_buffers(void);

static inline int get_recursion_context(int *recursion)
{
	int rctx;

	if (in_nmi())
		rctx = 3;
	else if (in_irq())
		rctx = 2;
	else if (in_softirq())
		rctx = 1;
	else
		rctx = 0;

	if (recursion[rctx])
		return -1;

	recursion[rctx]++;
	barrier();

	return rctx;
}

static inline void put_recursion_context(int *recursion, int rctx)
{
	barrier();
	recursion[rctx]--;
}

#endif /* _KERNEL_EVENTS_INTERNAL_H */