Root/drivers/oprofile/oprofilefs.c

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

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