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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 <linux/uaccess.h>
19
20 #include "oprof.h"
21
22 #define OPROFILEFS_MAGIC 0x6f70726f
23
24 DEFINE_RAW_SPINLOCK(oprofilefs_lock);
25
26 static 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(inode);
34 }
35 return inode;
36 }
37
38
39 static const struct super_operations s_ops = {
40 .statfs = simple_statfs,
41 .drop_inode = generic_delete_inode,
42 };
43
44
45 ssize_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
53 ssize_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 */
70 int 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
93 static 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
100 static 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
120 static 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
128 static const struct file_operations ulong_ro_fops = {
129 .read = ulong_read_file,
130 .open = simple_open,
131 .llseek = default_llseek,
132 };
133
134
135 static int __oprofilefs_create_file(struct dentry *root, char const *name,
136 const struct file_operations *fops, int perm, void *priv)
137 {
138 struct dentry *dentry;
139 struct inode *inode;
140
141 inode_lock(d_inode(root));
142 dentry = d_alloc_name(root, name);
143 if (!dentry) {
144 inode_unlock(d_inode(root));
145 return -ENOMEM;
146 }
147 inode = oprofilefs_get_inode(root->d_sb, S_IFREG | perm);
148 if (!inode) {
149 dput(dentry);
150 inode_unlock(d_inode(root));
151 return -ENOMEM;
152 }
153 inode->i_fop = fops;
154 inode->i_private = priv;
155 d_add(dentry, inode);
156 inode_unlock(d_inode(root));
157 return 0;
158 }
159
160
161 int oprofilefs_create_ulong(struct dentry *root,
162 char const *name, unsigned long *val)
163 {
164 return __oprofilefs_create_file(root, name,
165 &ulong_fops, 0644, val);
166 }
167
168
169 int oprofilefs_create_ro_ulong(struct dentry *root,
170 char const *name, unsigned long *val)
171 {
172 return __oprofilefs_create_file(root, name,
173 &ulong_ro_fops, 0444, val);
174 }
175
176
177 static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
178 {
179 atomic_t *val = file->private_data;
180 return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
181 }
182
183
184 static const struct file_operations atomic_ro_fops = {
185 .read = atomic_read_file,
186 .open = simple_open,
187 .llseek = default_llseek,
188 };
189
190
191 int oprofilefs_create_ro_atomic(struct dentry *root,
192 char const *name, atomic_t *val)
193 {
194 return __oprofilefs_create_file(root, name,
195 &atomic_ro_fops, 0444, val);
196 }
197
198
199 int oprofilefs_create_file(struct dentry *root,
200 char const *name, const struct file_operations *fops)
201 {
202 return __oprofilefs_create_file(root, name, fops, 0644, NULL);
203 }
204
205
206 int oprofilefs_create_file_perm(struct dentry *root,
207 char const *name, const struct file_operations *fops, int perm)
208 {
209 return __oprofilefs_create_file(root, name, fops, perm, NULL);
210 }
211
212
213 struct dentry *oprofilefs_mkdir(struct dentry *parent, char const *name)
214 {
215 struct dentry *dentry;
216 struct inode *inode;
217
218 inode_lock(d_inode(parent));
219 dentry = d_alloc_name(parent, name);
220 if (!dentry) {
221 inode_unlock(d_inode(parent));
222 return NULL;
223 }
224 inode = oprofilefs_get_inode(parent->d_sb, S_IFDIR | 0755);
225 if (!inode) {
226 dput(dentry);
227 inode_unlock(d_inode(parent));
228 return NULL;
229 }
230 inode->i_op = &simple_dir_inode_operations;
231 inode->i_fop = &simple_dir_operations;
232 d_add(dentry, inode);
233 inode_unlock(d_inode(parent));
234 return dentry;
235 }
236
237
238 static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
239 {
240 struct inode *root_inode;
241
242 sb->s_blocksize = PAGE_SIZE;
243 sb->s_blocksize_bits = PAGE_SHIFT;
244 sb->s_magic = OPROFILEFS_MAGIC;
245 sb->s_op = &s_ops;
246 sb->s_time_gran = 1;
247
248 root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
249 if (!root_inode)
250 return -ENOMEM;
251 root_inode->i_op = &simple_dir_inode_operations;
252 root_inode->i_fop = &simple_dir_operations;
253 sb->s_root = d_make_root(root_inode);
254 if (!sb->s_root)
255 return -ENOMEM;
256
257 oprofile_create_files(sb->s_root);
258
259 // FIXME: verify kill_litter_super removes our dentries
260 return 0;
261 }
262
263
264 static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
265 int flags, const char *dev_name, void *data)
266 {
267 return mount_single(fs_type, flags, data, oprofilefs_fill_super);
268 }
269
270
271 static struct file_system_type oprofilefs_type = {
272 .owner = THIS_MODULE,
273 .name = "oprofilefs",
274 .mount = oprofilefs_mount,
275 .kill_sb = kill_litter_super,
276 };
277 MODULE_ALIAS_FS("oprofilefs");
278
279
280 int __init oprofilefs_register(void)
281 {
282 return register_filesystem(&oprofilefs_type);
283 }
284
285
286 void __exit oprofilefs_unregister(void)
287 {
288 unregister_filesystem(&oprofilefs_type);
289 }