2005-04-17 00:20:36 +02:00
|
|
|
/**
|
|
|
|
* @file event_buffer.c
|
|
|
|
*
|
|
|
|
* @remark Copyright 2002 OProfile authors
|
|
|
|
* @remark Read the file COPYING
|
|
|
|
*
|
|
|
|
* @author John Levon <levon@movementarian.org>
|
|
|
|
*
|
|
|
|
* This is the global event buffer that the user-space
|
|
|
|
* daemon reads from. The event buffer is an untyped array
|
|
|
|
* of unsigned longs. Entries are prefixed by the
|
|
|
|
* escape value ESCAPE_CODE followed by an identifying code.
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include <linux/vmalloc.h>
|
|
|
|
#include <linux/oprofile.h>
|
|
|
|
#include <linux/sched.h>
|
2006-01-11 21:17:46 +01:00
|
|
|
#include <linux/capability.h>
|
2005-04-17 00:20:36 +02:00
|
|
|
#include <linux/dcookies.h>
|
|
|
|
#include <linux/fs.h>
|
|
|
|
#include <asm/uaccess.h>
|
|
|
|
|
|
|
|
#include "oprof.h"
|
|
|
|
#include "event_buffer.h"
|
|
|
|
#include "oprofile_stats.h"
|
|
|
|
|
2006-06-25 14:47:33 +02:00
|
|
|
DEFINE_MUTEX(buffer_mutex);
|
2005-04-17 00:20:36 +02:00
|
|
|
|
|
|
|
static unsigned long buffer_opened;
|
|
|
|
static DECLARE_WAIT_QUEUE_HEAD(buffer_wait);
|
|
|
|
static unsigned long * event_buffer;
|
|
|
|
static unsigned long buffer_size;
|
|
|
|
static unsigned long buffer_watershed;
|
|
|
|
static size_t buffer_pos;
|
2006-06-25 14:47:33 +02:00
|
|
|
/* atomic_t because wait_event checks it outside of buffer_mutex */
|
2005-04-17 00:20:36 +02:00
|
|
|
static atomic_t buffer_ready = ATOMIC_INIT(0);
|
|
|
|
|
|
|
|
/* Add an entry to the event buffer. When we
|
|
|
|
* get near to the end we wake up the process
|
|
|
|
* sleeping on the read() of the file.
|
|
|
|
*/
|
|
|
|
void add_event_entry(unsigned long value)
|
|
|
|
{
|
|
|
|
if (buffer_pos == buffer_size) {
|
|
|
|
atomic_inc(&oprofile_stats.event_lost_overflow);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
event_buffer[buffer_pos] = value;
|
|
|
|
if (++buffer_pos == buffer_size - buffer_watershed) {
|
|
|
|
atomic_set(&buffer_ready, 1);
|
|
|
|
wake_up(&buffer_wait);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
/* Wake up the waiting process if any. This happens
|
|
|
|
* on "echo 0 >/dev/oprofile/enable" so the daemon
|
|
|
|
* processes the data remaining in the event buffer.
|
|
|
|
*/
|
|
|
|
void wake_up_buffer_waiter(void)
|
|
|
|
{
|
2006-06-25 14:47:33 +02:00
|
|
|
mutex_lock(&buffer_mutex);
|
2005-04-17 00:20:36 +02:00
|
|
|
atomic_set(&buffer_ready, 1);
|
|
|
|
wake_up(&buffer_wait);
|
2006-06-25 14:47:33 +02:00
|
|
|
mutex_unlock(&buffer_mutex);
|
2005-04-17 00:20:36 +02:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
int alloc_event_buffer(void)
|
|
|
|
{
|
|
|
|
int err = -ENOMEM;
|
|
|
|
|
|
|
|
spin_lock(&oprofilefs_lock);
|
|
|
|
buffer_size = fs_buffer_size;
|
|
|
|
buffer_watershed = fs_buffer_watershed;
|
|
|
|
spin_unlock(&oprofilefs_lock);
|
|
|
|
|
|
|
|
if (buffer_watershed >= buffer_size)
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
event_buffer = vmalloc(sizeof(unsigned long) * buffer_size);
|
|
|
|
if (!event_buffer)
|
|
|
|
goto out;
|
|
|
|
|
|
|
|
err = 0;
|
|
|
|
out:
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
void free_event_buffer(void)
|
|
|
|
{
|
|
|
|
vfree(event_buffer);
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
static int event_buffer_open(struct inode * inode, struct file * file)
|
|
|
|
{
|
|
|
|
int err = -EPERM;
|
|
|
|
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
|
|
return -EPERM;
|
|
|
|
|
|
|
|
if (test_and_set_bit(0, &buffer_opened))
|
|
|
|
return -EBUSY;
|
|
|
|
|
|
|
|
/* Register as a user of dcookies
|
|
|
|
* to ensure they persist for the lifetime of
|
|
|
|
* the open event file
|
|
|
|
*/
|
|
|
|
err = -EINVAL;
|
|
|
|
file->private_data = dcookie_register();
|
|
|
|
if (!file->private_data)
|
|
|
|
goto out;
|
|
|
|
|
|
|
|
if ((err = oprofile_setup()))
|
|
|
|
goto fail;
|
|
|
|
|
|
|
|
/* NB: the actual start happens from userspace
|
|
|
|
* echo 1 >/dev/oprofile/enable
|
|
|
|
*/
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
fail:
|
|
|
|
dcookie_unregister(file->private_data);
|
|
|
|
out:
|
|
|
|
clear_bit(0, &buffer_opened);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
static int event_buffer_release(struct inode * inode, struct file * file)
|
|
|
|
{
|
|
|
|
oprofile_stop();
|
|
|
|
oprofile_shutdown();
|
|
|
|
dcookie_unregister(file->private_data);
|
|
|
|
buffer_pos = 0;
|
|
|
|
atomic_set(&buffer_ready, 0);
|
|
|
|
clear_bit(0, &buffer_opened);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
static ssize_t event_buffer_read(struct file * file, char __user * buf,
|
|
|
|
size_t count, loff_t * offset)
|
|
|
|
{
|
|
|
|
int retval = -EINVAL;
|
|
|
|
size_t const max = buffer_size * sizeof(unsigned long);
|
|
|
|
|
|
|
|
/* handling partial reads is more trouble than it's worth */
|
|
|
|
if (count != max || *offset)
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
wait_event_interruptible(buffer_wait, atomic_read(&buffer_ready));
|
|
|
|
|
|
|
|
if (signal_pending(current))
|
|
|
|
return -EINTR;
|
|
|
|
|
|
|
|
/* can't currently happen */
|
|
|
|
if (!atomic_read(&buffer_ready))
|
|
|
|
return -EAGAIN;
|
|
|
|
|
2006-06-25 14:47:33 +02:00
|
|
|
mutex_lock(&buffer_mutex);
|
2005-04-17 00:20:36 +02:00
|
|
|
|
|
|
|
atomic_set(&buffer_ready, 0);
|
|
|
|
|
|
|
|
retval = -EFAULT;
|
|
|
|
|
|
|
|
count = buffer_pos * sizeof(unsigned long);
|
|
|
|
|
|
|
|
if (copy_to_user(buf, event_buffer, count))
|
|
|
|
goto out;
|
|
|
|
|
|
|
|
retval = count;
|
|
|
|
buffer_pos = 0;
|
|
|
|
|
|
|
|
out:
|
2006-06-25 14:47:33 +02:00
|
|
|
mutex_unlock(&buffer_mutex);
|
2005-04-17 00:20:36 +02:00
|
|
|
return retval;
|
|
|
|
}
|
|
|
|
|
2007-02-12 09:55:34 +01:00
|
|
|
const struct file_operations event_buffer_fops = {
|
2005-04-17 00:20:36 +02:00
|
|
|
.open = event_buffer_open,
|
|
|
|
.release = event_buffer_release,
|
|
|
|
.read = event_buffer_read,
|
|
|
|
};
|