oprofilefs.c revision fc14f2fef682df677d64a145256dbd263df2aa7b 
1/**
2 * @file oprofilefs.c
3 *
4 * @remark Copyright 2002 OProfile authors
5 * @remark Read the file COPYING
6 *
7 * @author John Levon
8 *
9 * A simple filesystem for configuration and
10 * access of oprofile.
11 */
12
13#include <linux/init.h>
14#include <linux/module.h>
15#include <linux/oprofile.h>
16#include <linux/fs.h>
17#include <linux/pagemap.h>
18#include <asm/uaccess.h>
19
20#include "oprof.h"
21
22#define OPROFILEFS_MAGIC 0x6f70726f
23
24DEFINE_SPINLOCK(oprofilefs_lock);
25
26static struct inode *oprofilefs_get_inode(struct super_block *sb, int mode)
27{
28	struct inode *inode = new_inode(sb);
29
30	if (inode) {
31		inode->i_ino = get_next_ino();
32		inode->i_mode = mode;
33		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
34	}
35	return inode;
36}
37
38
39static const struct super_operations s_ops = {
40	.statfs		= simple_statfs,
41	.drop_inode 	= generic_delete_inode,
42};
43
44
45ssize_t oprofilefs_str_to_user(char const *str, char __user *buf, size_t count, loff_t *offset)
46{
47	return simple_read_from_buffer(buf, count, offset, str, strlen(str));
48}
49
50
51#define TMPBUFSIZE 50
52
53ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t count, loff_t *offset)
54{
55	char tmpbuf[TMPBUFSIZE];
56	size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
57	if (maxlen > TMPBUFSIZE)
58		maxlen = TMPBUFSIZE;
59	return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
60}
61
62
63int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
64{
65	char tmpbuf[TMPBUFSIZE];
66	unsigned long flags;
67
68	if (!count)
69		return 0;
70
71	if (count > TMPBUFSIZE - 1)
72		return -EINVAL;
73
74	memset(tmpbuf, 0x0, TMPBUFSIZE);
75
76	if (copy_from_user(tmpbuf, buf, count))
77		return -EFAULT;
78
79	spin_lock_irqsave(&oprofilefs_lock, flags);
80	*val = simple_strtoul(tmpbuf, NULL, 0);
81	spin_unlock_irqrestore(&oprofilefs_lock, flags);
82	return 0;
83}
84
85
86static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
87{
88	unsigned long *val = file->private_data;
89	return oprofilefs_ulong_to_user(*val, buf, count, offset);
90}
91
92
93static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
94{
95	unsigned long value;
96	int retval;
97
98	if (*offset)
99		return -EINVAL;
100
101	retval = oprofilefs_ulong_from_user(&value, buf, count);
102	if (retval)
103		return retval;
104
105	retval = oprofile_set_ulong(file->private_data, value);
106	if (retval)
107		return retval;
108
109	return count;
110}
111
112
113static int default_open(struct inode *inode, struct file *filp)
114{
115	if (inode->i_private)
116		filp->private_data = inode->i_private;
117	return 0;
118}
119
120
121static const struct file_operations ulong_fops = {
122	.read		= ulong_read_file,
123	.write		= ulong_write_file,
124	.open		= default_open,
125	.llseek		= default_llseek,
126};
127
128
129static const struct file_operations ulong_ro_fops = {
130	.read		= ulong_read_file,
131	.open		= default_open,
132	.llseek		= default_llseek,
133};
134
135
136static int __oprofilefs_create_file(struct super_block *sb,
137	struct dentry *root, char const *name, const struct file_operations *fops,
138	int perm, void *priv)
139{
140	struct dentry *dentry;
141	struct inode *inode;
142
143	dentry = d_alloc_name(root, name);
144	if (!dentry)
145		return -ENOMEM;
146	inode = oprofilefs_get_inode(sb, S_IFREG | perm);
147	if (!inode) {
148		dput(dentry);
149		return -ENOMEM;
150	}
151	inode->i_fop = fops;
152	d_add(dentry, inode);
153	dentry->d_inode->i_private = priv;
154	return 0;
155}
156
157
158int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
159	char const *name, unsigned long *val)
160{
161	return __oprofilefs_create_file(sb, root, name,
162					&ulong_fops, 0644, val);
163}
164
165
166int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
167	char const *name, unsigned long *val)
168{
169	return __oprofilefs_create_file(sb, root, name,
170					&ulong_ro_fops, 0444, val);
171}
172
173
174static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
175{
176	atomic_t *val = file->private_data;
177	return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
178}
179
180
181static const struct file_operations atomic_ro_fops = {
182	.read		= atomic_read_file,
183	.open		= default_open,
184	.llseek		= default_llseek,
185};
186
187
188int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
189	char const *name, atomic_t *val)
190{
191	return __oprofilefs_create_file(sb, root, name,
192					&atomic_ro_fops, 0444, val);
193}
194
195
196int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
197	char const *name, const struct file_operations *fops)
198{
199	return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
200}
201
202
203int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
204	char const *name, const struct file_operations *fops, int perm)
205{
206	return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
207}
208
209
210struct dentry *oprofilefs_mkdir(struct super_block *sb,
211	struct dentry *root, char const *name)
212{
213	struct dentry *dentry;
214	struct inode *inode;
215
216	dentry = d_alloc_name(root, name);
217	if (!dentry)
218		return NULL;
219	inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
220	if (!inode) {
221		dput(dentry);
222		return NULL;
223	}
224	inode->i_op = &simple_dir_inode_operations;
225	inode->i_fop = &simple_dir_operations;
226	d_add(dentry, inode);
227	return dentry;
228}
229
230
231static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
232{
233	struct inode *root_inode;
234	struct dentry *root_dentry;
235
236	sb->s_blocksize = PAGE_CACHE_SIZE;
237	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
238	sb->s_magic = OPROFILEFS_MAGIC;
239	sb->s_op = &s_ops;
240	sb->s_time_gran = 1;
241
242	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
243	if (!root_inode)
244		return -ENOMEM;
245	root_inode->i_op = &simple_dir_inode_operations;
246	root_inode->i_fop = &simple_dir_operations;
247	root_dentry = d_alloc_root(root_inode);
248	if (!root_dentry) {
249		iput(root_inode);
250		return -ENOMEM;
251	}
252
253	sb->s_root = root_dentry;
254
255	oprofile_create_files(sb, root_dentry);
256
257	// FIXME: verify kill_litter_super removes our dentries
258	return 0;
259}
260
261
262static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
263	int flags, const char *dev_name, void *data)
264{
265	return mount_single(fs_type, flags, data, oprofilefs_fill_super);
266}
267
268
269static struct file_system_type oprofilefs_type = {
270	.owner		= THIS_MODULE,
271	.name		= "oprofilefs",
272	.mount		= oprofilefs_mount,
273	.kill_sb	= kill_litter_super,
274};
275
276
277int __init oprofilefs_register(void)
278{
279	return register_filesystem(&oprofilefs_type);
280}
281
282
283void __exit oprofilefs_unregister(void)
284{
285	unregister_filesystem(&oprofilefs_type);
286}
287