src/kernel/linux/v4.19/drivers/oprofile/oprofile_files.c

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

#include <linux/fs.h>
#include <linux/oprofile.h>
#include <linux/jiffies.h>

#include "event_buffer.h"
#include "oprofile_stats.h"
#include "oprof.h"

#define BUFFER_SIZE_DEFAULT		131072
#define CPU_BUFFER_SIZE_DEFAULT		8192
#define BUFFER_WATERSHED_DEFAULT	32768	/* FIXME: tune */
#define TIME_SLICE_DEFAULT		1

unsigned long oprofile_buffer_size;
unsigned long oprofile_cpu_buffer_size;
unsigned long oprofile_buffer_watershed;
unsigned long oprofile_time_slice;

#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX

static ssize_t timeout_read(struct file *file, char __user *buf,
		size_t count, loff_t *offset)
{
	return oprofilefs_ulong_to_user(jiffies_to_msecs(oprofile_time_slice),
					buf, count, offset);
}


static ssize_t timeout_write(struct file *file, char const __user *buf,
		size_t count, loff_t *offset)
{
	unsigned long val;
	int retval;

	if (*offset)
		return -EINVAL;

	retval = oprofilefs_ulong_from_user(&val, buf, count);
	if (retval <= 0)
		return retval;

	retval = oprofile_set_timeout(val);

	if (retval)
		return retval;
	return count;
}


static const struct file_operations timeout_fops = {
	.read		= timeout_read,
	.write		= timeout_write,
	.llseek		= default_llseek,
};

#endif


static ssize_t depth_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
	return oprofilefs_ulong_to_user(oprofile_backtrace_depth, buf, count,
					offset);
}


static ssize_t depth_write(struct file *file, char const __user *buf, size_t count, loff_t *offset)
{
	unsigned long val;
	int retval;

	if (*offset)
		return -EINVAL;

	if (!oprofile_ops.backtrace)
		return -EINVAL;

	retval = oprofilefs_ulong_from_user(&val, buf, count);
	if (retval <= 0)
		return retval;

	retval = oprofile_set_ulong(&oprofile_backtrace_depth, val);
	if (retval)
		return retval;

	return count;
}


static const struct file_operations depth_fops = {
	.read		= depth_read,
	.write		= depth_write,
	.llseek		= default_llseek,
};


static ssize_t pointer_size_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
	return oprofilefs_ulong_to_user(sizeof(void *), buf, count, offset);
}


static const struct file_operations pointer_size_fops = {
	.read		= pointer_size_read,
	.llseek		= default_llseek,
};


static ssize_t cpu_type_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
	return oprofilefs_str_to_user(oprofile_ops.cpu_type, buf, count, offset);
}


static const struct file_operations cpu_type_fops = {
	.read		= cpu_type_read,
	.llseek		= default_llseek,
};


static ssize_t enable_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
	return oprofilefs_ulong_to_user(oprofile_started, buf, count, offset);
}


static ssize_t enable_write(struct file *file, char const __user *buf, size_t count, loff_t *offset)
{
	unsigned long val;
	int retval;

	if (*offset)
		return -EINVAL;

	retval = oprofilefs_ulong_from_user(&val, buf, count);
	if (retval <= 0)
		return retval;

	retval = 0;
	if (val)
		retval = oprofile_start();
	else
		oprofile_stop();

	if (retval)
		return retval;
	return count;
}


static const struct file_operations enable_fops = {
	.read		= enable_read,
	.write		= enable_write,
	.llseek		= default_llseek,
};


static ssize_t dump_write(struct file *file, char const __user *buf, size_t count, loff_t *offset)
{
	wake_up_buffer_waiter();
	return count;
}


static const struct file_operations dump_fops = {
	.write		= dump_write,
	.llseek		= noop_llseek,
};

void oprofile_create_files(struct dentry *root)
{
	/* reinitialize default values */
	oprofile_buffer_size =		BUFFER_SIZE_DEFAULT;
	oprofile_cpu_buffer_size =	CPU_BUFFER_SIZE_DEFAULT;
	oprofile_buffer_watershed =	BUFFER_WATERSHED_DEFAULT;
	oprofile_time_slice =		msecs_to_jiffies(TIME_SLICE_DEFAULT);

	oprofilefs_create_file(root, "enable", &enable_fops);
	oprofilefs_create_file_perm(root, "dump", &dump_fops, 0666);
	oprofilefs_create_file(root, "buffer", &event_buffer_fops);
	oprofilefs_create_ulong(root, "buffer_size", &oprofile_buffer_size);
	oprofilefs_create_ulong(root, "buffer_watershed", &oprofile_buffer_watershed);
	oprofilefs_create_ulong(root, "cpu_buffer_size", &oprofile_cpu_buffer_size);
	oprofilefs_create_file(root, "cpu_type", &cpu_type_fops);
	oprofilefs_create_file(root, "backtrace_depth", &depth_fops);
	oprofilefs_create_file(root, "pointer_size", &pointer_size_fops);
#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
	oprofilefs_create_file(root, "time_slice", &timeout_fops);
#endif
	oprofile_create_stats_files(root);
	if (oprofile_ops.create_files)
		oprofile_ops.create_files(root);
}