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
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(inode);
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 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 if (!root)
142 return -ENOMEM;
143
144 inode_lock(d_inode(root));
145 dentry = d_alloc_name(root, name);
146 if (!dentry) {
147 inode_unlock(d_inode(root));
148 return -ENOMEM;
149 }
150 inode = oprofilefs_get_inode(root->d_sb, S_IFREG | perm);
151 if (!inode) {
152 dput(dentry);
153 inode_unlock(d_inode(root));
154 return -ENOMEM;
155 }
156 inode->i_fop = fops;
157 inode->i_private = priv;
158 d_add(dentry, inode);
159 inode_unlock(d_inode(root));
160 return 0;
161}
162
163
164int oprofilefs_create_ulong(struct dentry *root,
165 char const *name, unsigned long *val)
166{
167 return __oprofilefs_create_file(root, name,
168 &ulong_fops, 0644, val);
169}
170
171
172int oprofilefs_create_ro_ulong(struct dentry *root,
173 char const *name, unsigned long *val)
174{
175 return __oprofilefs_create_file(root, name,
176 &ulong_ro_fops, 0444, val);
177}
178
179
180static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
181{
182 atomic_t *val = file->private_data;
183 return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
184}
185
186
187static const struct file_operations atomic_ro_fops = {
188 .read = atomic_read_file,
189 .open = simple_open,
190 .llseek = default_llseek,
191};
192
193
194int oprofilefs_create_ro_atomic(struct dentry *root,
195 char const *name, atomic_t *val)
196{
197 return __oprofilefs_create_file(root, name,
198 &atomic_ro_fops, 0444, val);
199}
200
201
202int oprofilefs_create_file(struct dentry *root,
203 char const *name, const struct file_operations *fops)
204{
205 return __oprofilefs_create_file(root, name, fops, 0644, NULL);
206}
207
208
209int oprofilefs_create_file_perm(struct dentry *root,
210 char const *name, const struct file_operations *fops, int perm)
211{
212 return __oprofilefs_create_file(root, name, fops, perm, NULL);
213}
214
215
216struct dentry *oprofilefs_mkdir(struct dentry *parent, char const *name)
217{
218 struct dentry *dentry;
219 struct inode *inode;
220
221 inode_lock(d_inode(parent));
222 dentry = d_alloc_name(parent, name);
223 if (!dentry) {
224 inode_unlock(d_inode(parent));
225 return NULL;
226 }
227 inode = oprofilefs_get_inode(parent->d_sb, S_IFDIR | 0755);
228 if (!inode) {
229 dput(dentry);
230 inode_unlock(d_inode(parent));
231 return NULL;
232 }
233 inode->i_op = &simple_dir_inode_operations;
234 inode->i_fop = &simple_dir_operations;
235 d_add(dentry, inode);
236 inode_unlock(d_inode(parent));
237 return dentry;
238}
239
240
241static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
242{
243 struct inode *root_inode;
244
245 sb->s_blocksize = PAGE_SIZE;
246 sb->s_blocksize_bits = PAGE_SHIFT;
247 sb->s_magic = OPROFILEFS_MAGIC;
248 sb->s_op = &s_ops;
249 sb->s_time_gran = 1;
250
251 root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
252 if (!root_inode)
253 return -ENOMEM;
254 root_inode->i_op = &simple_dir_inode_operations;
255 root_inode->i_fop = &simple_dir_operations;
256 sb->s_root = d_make_root(root_inode);
257 if (!sb->s_root)
258 return -ENOMEM;
259
260 oprofile_create_files(sb->s_root);
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};
280MODULE_ALIAS_FS("oprofilefs");
281
282
283int __init oprofilefs_register(void)
284{
285 return register_filesystem(&oprofilefs_type);
286}
287
288
289void __exit oprofilefs_unregister(void)
290{
291 unregister_filesystem(&oprofilefs_type);
292}
293