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/**
* @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 */
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