oprofilefs.c revision 48fde701aff662559b38d9a609574068f22d00fe 
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_RAW_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
63/*
64 * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
65 * unchanged and might be uninitialized. This follows write syscall
66 * implementation when count is zero: "If count is zero ... [and if]
67 * no errors are detected, 0 will be returned without causing any
68 * other effect." (man 2 write)
69 */
70int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
71{
72	char tmpbuf[TMPBUFSIZE];
73	unsigned long flags;
74
75	if (!count)
76		return 0;
77
78	if (count > TMPBUFSIZE - 1)
79		return -EINVAL;
80
81	memset(tmpbuf, 0x0, TMPBUFSIZE);
82
83	if (copy_from_user(tmpbuf, buf, count))
84		return -EFAULT;
85
86	raw_spin_lock_irqsave(&oprofilefs_lock, flags);
87	*val = simple_strtoul(tmpbuf, NULL, 0);
88	raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);
89	return count;
90}
91
92
93static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
94{
95	unsigned long *val = file->private_data;
96	return oprofilefs_ulong_to_user(*val, buf, count, offset);
97}
98
99
100static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
101{
102	unsigned long value;
103	int retval;
104
105	if (*offset)
106		return -EINVAL;
107
108	retval = oprofilefs_ulong_from_user(&value, buf, count);
109	if (retval <= 0)
110		return retval;
111
112	retval = oprofile_set_ulong(file->private_data, value);
113	if (retval)
114		return retval;
115
116	return count;
117}
118
119
120static int default_open(struct inode *inode, struct file *filp)
121{
122	if (inode->i_private)
123		filp->private_data = inode->i_private;
124	return 0;
125}
126
127
128static const struct file_operations ulong_fops = {
129	.read		= ulong_read_file,
130	.write		= ulong_write_file,
131	.open		= default_open,
132	.llseek		= default_llseek,
133};
134
135
136static const struct file_operations ulong_ro_fops = {
137	.read		= ulong_read_file,
138	.open		= default_open,
139	.llseek		= default_llseek,
140};
141
142
143static int __oprofilefs_create_file(struct super_block *sb,
144	struct dentry *root, char const *name, const struct file_operations *fops,
145	int perm, void *priv)
146{
147	struct dentry *dentry;
148	struct inode *inode;
149
150	dentry = d_alloc_name(root, name);
151	if (!dentry)
152		return -ENOMEM;
153	inode = oprofilefs_get_inode(sb, S_IFREG | perm);
154	if (!inode) {
155		dput(dentry);
156		return -ENOMEM;
157	}
158	inode->i_fop = fops;
159	d_add(dentry, inode);
160	dentry->d_inode->i_private = priv;
161	return 0;
162}
163
164
165int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
166	char const *name, unsigned long *val)
167{
168	return __oprofilefs_create_file(sb, root, name,
169					&ulong_fops, 0644, val);
170}
171
172
173int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
174	char const *name, unsigned long *val)
175{
176	return __oprofilefs_create_file(sb, root, name,
177					&ulong_ro_fops, 0444, val);
178}
179
180
181static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
182{
183	atomic_t *val = file->private_data;
184	return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
185}
186
187
188static const struct file_operations atomic_ro_fops = {
189	.read		= atomic_read_file,
190	.open		= default_open,
191	.llseek		= default_llseek,
192};
193
194
195int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
196	char const *name, atomic_t *val)
197{
198	return __oprofilefs_create_file(sb, root, name,
199					&atomic_ro_fops, 0444, val);
200}
201
202
203int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
204	char const *name, const struct file_operations *fops)
205{
206	return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
207}
208
209
210int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
211	char const *name, const struct file_operations *fops, int perm)
212{
213	return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
214}
215
216
217struct dentry *oprofilefs_mkdir(struct super_block *sb,
218	struct dentry *root, char const *name)
219{
220	struct dentry *dentry;
221	struct inode *inode;
222
223	dentry = d_alloc_name(root, name);
224	if (!dentry)
225		return NULL;
226	inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
227	if (!inode) {
228		dput(dentry);
229		return NULL;
230	}
231	inode->i_op = &simple_dir_inode_operations;
232	inode->i_fop = &simple_dir_operations;
233	d_add(dentry, inode);
234	return dentry;
235}
236
237
238static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
239{
240	struct inode *root_inode;
241	struct dentry *root_dentry;
242
243	sb->s_blocksize = PAGE_CACHE_SIZE;
244	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
245	sb->s_magic = OPROFILEFS_MAGIC;
246	sb->s_op = &s_ops;
247	sb->s_time_gran = 1;
248
249	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
250	if (!root_inode)
251		return -ENOMEM;
252	root_inode->i_op = &simple_dir_inode_operations;
253	root_inode->i_fop = &simple_dir_operations;
254	root_dentry = d_make_root(root_inode);
255	if (!root_dentry)
256		return -ENOMEM;
257
258	sb->s_root = root_dentry;
259
260	oprofile_create_files(sb, root_dentry);
261
262	// FIXME: verify kill_litter_super removes our dentries
263	return 0;
264}
265
266
267static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
268	int flags, const char *dev_name, void *data)
269{
270	return mount_single(fs_type, flags, data, oprofilefs_fill_super);
271}
272
273
274static struct file_system_type oprofilefs_type = {
275	.owner		= THIS_MODULE,
276	.name		= "oprofilefs",
277	.mount		= oprofilefs_mount,
278	.kill_sb	= kill_litter_super,
279};
280
281
282int __init oprofilefs_register(void)
283{
284	return register_filesystem(&oprofilefs_type);
285}
286
287
288void __exit oprofilefs_unregister(void)
289{
290	unregister_filesystem(&oprofilefs_type);
291}
292