[deliverable/linux.git] / drivers / oprofile / cpu_buffer.h

/**
 * @file cpu_buffer.h
 *
 * @remark Copyright 2002 OProfile authors
 * @remark Read the file COPYING
 *
 * @author John Levon <levon@movementarian.org>
 */

#ifndef OPROFILE_CPU_BUFFER_H
#define OPROFILE_CPU_BUFFER_H

#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/cache.h>
#include <linux/sched.h>

struct task_struct;

int alloc_cpu_buffers(void);
void free_cpu_buffers(void);

void start_cpu_work(void);
void end_cpu_work(void);

/* CPU buffer is composed of such entries (which are
 * also used for context switch notes)
 */
struct op_sample {
	unsigned long eip;
	unsigned long event;
};

struct oprofile_cpu_buffer {
	volatile unsigned long head_pos;
	volatile unsigned long tail_pos;
	unsigned long buffer_size;
	struct task_struct *last_task;
	int last_is_kernel;
	int tracing;
	struct op_sample *buffer;
	unsigned long sample_received;
	unsigned long sample_lost_overflow;
	unsigned long backtrace_aborted;
	unsigned long sample_invalid_eip;
	int cpu;
	struct delayed_work work;
};

DECLARE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);

void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf);

static inline
struct op_sample *cpu_buffer_write_entry(struct oprofile_cpu_buffer *cpu_buf)
{
	return &cpu_buf->buffer[cpu_buf->head_pos];
}

static inline
void cpu_buffer_write_commit(struct oprofile_cpu_buffer *b)
{
	unsigned long new_head = b->head_pos + 1;

	/*
	 * Ensure anything written to the slot before we increment is
	 * visible
	 */
	wmb();

	if (new_head < b->buffer_size)
		b->head_pos = new_head;
	else
		b->head_pos = 0;
}

static inline
struct op_sample *cpu_buffer_read_entry(struct oprofile_cpu_buffer *cpu_buf)
{
	return &cpu_buf->buffer[cpu_buf->tail_pos];
}

/* "acquire" as many cpu buffer slots as we can */
static inline
unsigned long cpu_buffer_entries(struct oprofile_cpu_buffer *b)
{
	unsigned long head = b->head_pos;
	unsigned long tail = b->tail_pos;

	/*
	 * Subtle. This resets the persistent last_task
	 * and in_kernel values used for switching notes.
	 * BUT, there is a small window between reading
	 * head_pos, and this call, that means samples
	 * can appear at the new head position, but not
	 * be prefixed with the notes for switching
	 * kernel mode or a task switch. This small hole
	 * can lead to mis-attribution or samples where
	 * we don't know if it's in the kernel or not,
	 * at the start of an event buffer.
	 */
	cpu_buffer_reset(b);

	if (head >= tail)
		return head - tail;

	return head + (b->buffer_size - tail);
}

/* transient events for the CPU buffer -> event buffer */
#define CPU_IS_KERNEL 1
#define CPU_TRACE_BEGIN 2
#define IBS_FETCH_BEGIN 3
#define IBS_OP_BEGIN    4

#endif /* OPROFILE_CPU_BUFFER_H */
Commit	Line	Data
1da177e4 LT	1	/**
	2	* @file cpu_buffer.h
	3	*
	4	* @remark Copyright 2002 OProfile authors
	5	* @remark Read the file COPYING
	6	*
	7	* @author John Levon <levon@movementarian.org>
	8	*/
	9
	10	#ifndef OPROFILE_CPU_BUFFER_H
	11	#define OPROFILE_CPU_BUFFER_H
	12
	13	#include <linux/types.h>
	14	#include <linux/spinlock.h>
	15	#include <linux/workqueue.h>
	16	#include <linux/cache.h>
608dfddd	17	#include <linux/sched.h>
6a18037d	18
1da177e4	19	struct task_struct;
6a18037d	20
1da177e4 LT	21	int alloc_cpu_buffers(void);
	22	void free_cpu_buffers(void);
	23
	24	void start_cpu_work(void);
	25	void end_cpu_work(void);
	26
	27	/* CPU buffer is composed of such entries (which are
	28	* also used for context switch notes)
	29	*/
	30	struct op_sample {
	31	unsigned long eip;
	32	unsigned long event;
	33	};
6a18037d	34
1da177e4 LT	35	struct oprofile_cpu_buffer {
	36	volatile unsigned long head_pos;
	37	volatile unsigned long tail_pos;
	38	unsigned long buffer_size;
25ad2913	39	struct task_struct *last_task;
1da177e4 LT	40	int last_is_kernel;
1da177e4 LT	41	int tracing;
25ad2913	42	struct op_sample *buffer;
1da177e4 LT	43	unsigned long sample_received;
	44	unsigned long sample_lost_overflow;
	45	unsigned long backtrace_aborted;
df9d177a	46	unsigned long sample_invalid_eip;
1da177e4	47	int cpu;
c4028958	48	struct delayed_work work;
8b8b4988	49	};
1da177e4	50
608dfddd	51	DECLARE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);
1da177e4	52
25ad2913	53	void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf);
1da177e4	54
7d468abe RR	55	static inline
	56	struct op_sample cpu_buffer_write_entry(struct oprofile_cpu_buffer cpu_buf)
	57	{
	58	return &cpu_buf->buffer[cpu_buf->head_pos];
	59	}
	60
229234ae RR	61	static inline
	62	void cpu_buffer_write_commit(struct oprofile_cpu_buffer *b)
	63	{
	64	unsigned long new_head = b->head_pos + 1;
	65
	66	/*
	67	* Ensure anything written to the slot before we increment is
	68	* visible
	69	*/
	70	wmb();
	71
	72	if (new_head < b->buffer_size)
	73	b->head_pos = new_head;
	74	else
	75	b->head_pos = 0;
	76	}
	77
7d468abe RR	78	static inline
	79	struct op_sample cpu_buffer_read_entry(struct oprofile_cpu_buffer cpu_buf)
	80	{
	81	return &cpu_buf->buffer[cpu_buf->tail_pos];
	82	}
	83
bf589e32 RR	84	/* "acquire" as many cpu buffer slots as we can */
	85	static inline
	86	unsigned long cpu_buffer_entries(struct oprofile_cpu_buffer *b)
	87	{
	88	unsigned long head = b->head_pos;
	89	unsigned long tail = b->tail_pos;
	90
	91	/*
	92	* Subtle. This resets the persistent last_task
	93	* and in_kernel values used for switching notes.
	94	* BUT, there is a small window between reading
	95	* head_pos, and this call, that means samples
	96	* can appear at the new head position, but not
	97	* be prefixed with the notes for switching
	98	* kernel mode or a task switch. This small hole
	99	* can lead to mis-attribution or samples where
	100	* we don't know if it's in the kernel or not,
	101	* at the start of an event buffer.
	102	*/
	103	cpu_buffer_reset(b);
	104
	105	if (head >= tail)
	106	return head - tail;
	107
	108	return head + (b->buffer_size - tail);
	109	}
	110
1da177e4 LT	111	/* transient events for the CPU buffer -> event buffer */
	112	#define CPU_IS_KERNEL 1
	113	#define CPU_TRACE_BEGIN 2
345c2573 BK	114	#define IBS_FETCH_BEGIN 3
345c2573 BK	115	#define IBS_OP_BEGIN 4
1da177e4 LT	116
1da177e4 LT	117	#endif /* OPROFILE_CPU_BUFFER_H */