oprofilefs.c revision 234e340582901211f40d8c732afc49f0630ecf05 
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 const struct file_operations ulong_fops = {
121	.read		= ulong_read_file,
122	.write		= ulong_write_file,
123	.open		= simple_open,
124	.llseek		= default_llseek,
125};
126
127
128static const struct file_operations ulong_ro_fops = {
129	.read		= ulong_read_file,
130	.open		= simple_open,
131	.llseek		= default_llseek,
132};
133
134
135static int __oprofilefs_create_file(struct super_block *sb,
136	struct dentry *root, char const *name, const struct file_operations *fops,
137	int perm, void *priv)
138{
139	struct dentry *dentry;
140	struct inode *inode;
141
142	dentry = d_alloc_name(root, name);
143	if (!dentry)
144		return -ENOMEM;
145	inode = oprofilefs_get_inode(sb, S_IFREG | perm);
146	if (!inode) {
147		dput(dentry);
148		return -ENOMEM;
149	}
150	inode->i_fop = fops;
151	d_add(dentry, inode);
152	dentry->d_inode->i_private = priv;
153	return 0;
154}
155
156
157int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
158	char const *name, unsigned long *val)
159{
160	return __oprofilefs_create_file(sb, root, name,
161					&ulong_fops, 0644, val);
162}
163
164
165int oprofilefs_create_ro_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_ro_fops, 0444, val);
170}
171
172
173static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
174{
175	atomic_t *val = file->private_data;
176	return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
177}
178
179
180static const struct file_operations atomic_ro_fops = {
181	.read		= atomic_read_file,
182	.open		= simple_open,
183	.llseek		= default_llseek,
184};
185
186
187int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
188	char const *name, atomic_t *val)
189{
190	return __oprofilefs_create_file(sb, root, name,
191					&atomic_ro_fops, 0444, val);
192}
193
194
195int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
196	char const *name, const struct file_operations *fops)
197{
198	return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
199}
200
201
202int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
203	char const *name, const struct file_operations *fops, int perm)
204{
205	return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
206}
207
208
209struct dentry *oprofilefs_mkdir(struct super_block *sb,
210	struct dentry *root, char const *name)
211{
212	struct dentry *dentry;
213	struct inode *inode;
214
215	dentry = d_alloc_name(root, name);
216	if (!dentry)
217		return NULL;
218	inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
219	if (!inode) {
220		dput(dentry);
221		return NULL;
222	}
223	inode->i_op = &simple_dir_inode_operations;
224	inode->i_fop = &simple_dir_operations;
225	d_add(dentry, inode);
226	return dentry;
227}
228
229
230static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
231{
232	struct inode *root_inode;
233
234	sb->s_blocksize = PAGE_CACHE_SIZE;
235	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
236	sb->s_magic = OPROFILEFS_MAGIC;
237	sb->s_op = &s_ops;
238	sb->s_time_gran = 1;
239
240	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
241	if (!root_inode)
242		return -ENOMEM;
243	root_inode->i_op = &simple_dir_inode_operations;
244	root_inode->i_fop = &simple_dir_operations;
245	sb->s_root = d_make_root(root_inode);
246	if (!sb->s_root)
247		return -ENOMEM;
248
249	oprofile_create_files(sb, sb->s_root);
250
251	// FIXME: verify kill_litter_super removes our dentries
252	return 0;
253}
254
255
256static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
257	int flags, const char *dev_name, void *data)
258{
259	return mount_single(fs_type, flags, data, oprofilefs_fill_super);
260}
261
262
263static struct file_system_type oprofilefs_type = {
264	.owner		= THIS_MODULE,
265	.name		= "oprofilefs",
266	.mount		= oprofilefs_mount,
267	.kill_sb	= kill_litter_super,
268};
269
270
271int __init oprofilefs_register(void)
272{
273	return register_filesystem(&oprofilefs_type);
274}
275
276
277void __exit oprofilefs_unregister(void)
278{
279	unregister_filesystem(&oprofilefs_type);
280}
281