summaryrefslogtreecommitdiff
path: root/drivers/oprofile/oprofilefs.c
blob: dd92c5edf219453aac0bb98d161fc1136395f1c7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
/**
 * @file oprofilefs.c
 *
 * @remark Copyright 2002 OProfile authors
 * @remark Read the file COPYING
 *
 * @author John Levon
 *
 * A simple filesystem for configuration and
 * access of oprofile.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/oprofile.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <asm/uaccess.h>

#include "oprof.h"

#define OPROFILEFS_MAGIC 0x6f70726f

DEFINE_RAW_SPINLOCK(oprofilefs_lock);

static struct inode *oprofilefs_get_inode(struct super_block *sb, int mode)
{
	struct inode *inode = new_inode(sb);

	if (inode) {
		inode->i_ino = get_next_ino();
		inode->i_mode = mode;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	}
	return inode;
}


static const struct super_operations s_ops = {
	.statfs		= simple_statfs,
	.drop_inode 	= generic_delete_inode,
};


ssize_t oprofilefs_str_to_user(char const *str, char __user *buf, size_t count, loff_t *offset)
{
	return simple_read_from_buffer(buf, count, offset, str, strlen(str));
}


#define TMPBUFSIZE 50

ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t count, loff_t *offset)
{
	char tmpbuf[TMPBUFSIZE];
	size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
	if (maxlen > TMPBUFSIZE)
		maxlen = TMPBUFSIZE;
	return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
}


/*
 * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
 * unchanged and might be uninitialized. This follows write syscall
 * implementation when count is zero: "If count is zero ... [and if]
 * no errors are detected, 0 will be returned without causing any
 * other effect." (man 2 write)
 */
int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
{
	char tmpbuf[TMPBUFSIZE];
	unsigned long flags;

	if (!count)
		return 0;

	if (count > TMPBUFSIZE - 1)
		return -EINVAL;

	memset(tmpbuf, 0x0, TMPBUFSIZE);

	if (copy_from_user(tmpbuf, buf, count))
		return -EFAULT;

	raw_spin_lock_irqsave(&oprofilefs_lock, flags);
	*val = simple_strtoul(tmpbuf, NULL, 0);
	raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);
	return count;
}


static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
	unsigned long *val = file->private_data;
	return oprofilefs_ulong_to_user(*val, buf, count, offset);
}


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

	if (*offset)
		return -EINVAL;

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

	retval = oprofile_set_ulong(file->private_data, value);
	if (retval)
		return retval;

	return count;
}


static const struct file_operations ulong_fops = {
	.read		= ulong_read_file,
	.write		= ulong_write_file,
	.open		= simple_open,
	.llseek		= default_llseek,
};


static const struct file_operations ulong_ro_fops = {
	.read		= ulong_read_file,
	.open		= simple_open,
	.llseek		= default_llseek,
};


static int __oprofilefs_create_file(struct dentry *root, char const *name,
	const struct file_operations *fops, int perm, void *priv)
{
	struct dentry *dentry;
	struct inode *inode;

	mutex_lock(&d_inode(root)->i_mutex);
	dentry = d_alloc_name(root, name);
	if (!dentry) {
		mutex_unlock(&d_inode(root)->i_mutex);
		return -ENOMEM;
	}
	inode = oprofilefs_get_inode(root->d_sb, S_IFREG | perm);
	if (!inode) {
		dput(dentry);
		mutex_unlock(&d_inode(root)->i_mutex);
		return -ENOMEM;
	}
	inode->i_fop = fops;
	inode->i_private = priv;
	d_add(dentry, inode);
	mutex_unlock(&d_inode(root)->i_mutex);
	return 0;
}


int oprofilefs_create_ulong(struct dentry *root,
	char const *name, unsigned long *val)
{
	return __oprofilefs_create_file(root, name,
					&ulong_fops, 0644, val);
}


int oprofilefs_create_ro_ulong(struct dentry *root,
	char const *name, unsigned long *val)
{
	return __oprofilefs_create_file(root, name,
					&ulong_ro_fops, 0444, val);
}


static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
	atomic_t *val = file->private_data;
	return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
}


static const struct file_operations atomic_ro_fops = {
	.read		= atomic_read_file,
	.open		= simple_open,
	.llseek		= default_llseek,
};


int oprofilefs_create_ro_atomic(struct dentry *root,
	char const *name, atomic_t *val)
{
	return __oprofilefs_create_file(root, name,
					&atomic_ro_fops, 0444, val);
}


int oprofilefs_create_file(struct dentry *root,
	char const *name, const struct file_operations *fops)
{
	return __oprofilefs_create_file(root, name, fops, 0644, NULL);
}


int oprofilefs_create_file_perm(struct dentry *root,
	char const *name, const struct file_operations *fops, int perm)
{
	return __oprofilefs_create_file(root, name, fops, perm, NULL);
}


struct dentry *oprofilefs_mkdir(struct dentry *parent, char const *name)
{
	struct dentry *dentry;
	struct inode *inode;

	mutex_lock(&d_inode(parent)->i_mutex);
	dentry = d_alloc_name(parent, name);
	if (!dentry) {
		mutex_unlock(&d_inode(parent)->i_mutex);
		return NULL;
	}
	inode = oprofilefs_get_inode(parent->d_sb, S_IFDIR | 0755);
	if (!inode) {
		dput(dentry);
		mutex_unlock(&d_inode(parent)->i_mutex);
		return NULL;
	}
	inode->i_op = &simple_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	d_add(dentry, inode);
	mutex_unlock(&d_inode(parent)->i_mutex);
	return dentry;
}


static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
{
	struct inode *root_inode;

	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = OPROFILEFS_MAGIC;
	sb->s_op = &s_ops;
	sb->s_time_gran = 1;

	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
	if (!root_inode)
		return -ENOMEM;
	root_inode->i_op = &simple_dir_inode_operations;
	root_inode->i_fop = &simple_dir_operations;
	sb->s_root = d_make_root(root_inode);
	if (!sb->s_root)
		return -ENOMEM;

	oprofile_create_files(sb->s_root);

	// FIXME: verify kill_litter_super removes our dentries
	return 0;
}


static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data)
{
	return mount_single(fs_type, flags, data, oprofilefs_fill_super);
}


static struct file_system_type oprofilefs_type = {
	.owner		= THIS_MODULE,
	.name		= "oprofilefs",
	.mount		= oprofilefs_mount,
	.kill_sb	= kill_litter_super,
};
MODULE_ALIAS_FS("oprofilefs");


int __init oprofilefs_register(void)
{
	return register_filesystem(&oprofilefs_type);
}


void __exit oprofilefs_unregister(void)
{
	unregister_filesystem(&oprofilefs_type);
}