cpu_buffer.h

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#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>
#include <linux/ring_buffer.h>

struct task_struct;

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

void start_cpu_work(void);
void end_cpu_work(void);
void flush_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;
    unsigned long data[0];
};

struct op_entry;

struct oprofile_cpu_buffer {
    unsigned long buffer_size;
    struct task_struct *last_task;
    int last_is_kernel;
    int tracing;
    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, op_cpu_buffer);

/*
 * Resets the cpu buffer to a sane state.
 *
 * reset these to invalid values; the next sample collected will
 * populate the buffer with proper values to initialize the buffer
 */
static inline void op_cpu_buffer_reset(int cpu)
{
    struct oprofile_cpu_buffer *cpu_buf = &per_cpu(op_cpu_buffer, cpu);

    cpu_buf->last_is_kernel = -1;
    cpu_buf->last_task = NULL;
}

/*
 * op_cpu_buffer_add_data() and op_cpu_buffer_write_commit() may be
 * called only if op_cpu_buffer_write_reserve() did not return NULL or
 * entry->event != NULL, otherwise entry->size or entry->event will be
 * used uninitialized.
 */

struct op_sample
*op_cpu_buffer_write_reserve(struct op_entry *entry, unsigned long size);
int op_cpu_buffer_write_commit(struct op_entry *entry);
struct op_sample *op_cpu_buffer_read_entry(struct op_entry *entry, int cpu);
unsigned long op_cpu_buffer_entries(int cpu);

/* returns the remaining free size of data in the entry */
static inline
int op_cpu_buffer_add_data(struct op_entry *entry, unsigned long val)
{
    if (!entry->size)
        return 0;
    *entry->data = val;
    entry->size--;
    entry->data++;
    return entry->size;
}

/* returns the size of data in the entry */
static inline
int op_cpu_buffer_get_size(struct op_entry *entry)
{
    return entry->size;
}

/* returns 0 if empty or the size of data including the current value */
static inline
int op_cpu_buffer_get_data(struct op_entry *entry, unsigned long *val)
{
    int size = entry->size;
    if (!size)
        return 0;
    *val = *entry->data;
    entry->size--;
    entry->data++;
    return size;
}

/* extra data flags */
#define KERNEL_CTX_SWITCH   (1UL << 0)
#define IS_KERNEL       (1UL << 1)
#define TRACE_BEGIN     (1UL << 2)
#define USER_CTX_SWITCH     (1UL << 3)

#endif /* OPROFILE_CPU_BUFFER_H */