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/fs_context.h>
18#include <linux/pagemap.h>
19#include <linux/uaccess.h>
20
21#include "oprof.h"
22
23#define OPROFILEFS_MAGIC 0x6f70726f
24
25DEFINE_RAW_SPINLOCK(oprofilefs_lock);
26
27static struct inode *oprofilefs_get_inode(struct super_block *sb, int mode)
28{
29	struct inode *inode = new_inode(sb);
30
31	if (inode) {
32		inode->i_ino = get_next_ino();
33		inode->i_mode = mode;
34		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
35	}
36	return inode;
37}
38
39
40static const struct super_operations s_ops = {
41	.statfs		= simple_statfs,
42	.drop_inode 	= generic_delete_inode,
43};
44
45
46ssize_t oprofilefs_str_to_user(char const *str, char __user *buf, size_t count, loff_t *offset)
47{
48	return simple_read_from_buffer(buf, count, offset, str, strlen(str));
49}
50
51
52#define TMPBUFSIZE 50
53
54ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t count, loff_t *offset)
55{
56	char tmpbuf[TMPBUFSIZE];
57	size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
58	if (maxlen > TMPBUFSIZE)
59		maxlen = TMPBUFSIZE;
60	return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
61}
62
63
64/*
65 * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
66 * unchanged and might be uninitialized. This follows write syscall
67 * implementation when count is zero: "If count is zero ... [and if]
68 * no errors are detected, 0 will be returned without causing any
69 * other effect." (man 2 write)
70 */
71int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
72{
73	char tmpbuf[TMPBUFSIZE];
74	unsigned long flags;
75
76	if (!count)
77		return 0;
78
79	if (count > TMPBUFSIZE - 1)
80		return -EINVAL;
81
82	memset(tmpbuf, 0x0, TMPBUFSIZE);
83
84	if (copy_from_user(tmpbuf, buf, count))
85		return -EFAULT;
86
87	raw_spin_lock_irqsave(&oprofilefs_lock, flags);
88	*val = simple_strtoul(tmpbuf, NULL, 0);
89	raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);
90	return count;
91}
92
93
94static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
95{
96	unsigned long *val = file->private_data;
97	return oprofilefs_ulong_to_user(*val, buf, count, offset);
98}
99
100
101static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
102{
103	unsigned long value;
104	int retval;
105
106	if (*offset)
107		return -EINVAL;
108
109	retval = oprofilefs_ulong_from_user(&value, buf, count);
110	if (retval <= 0)
111		return retval;
112
113	retval = oprofile_set_ulong(file->private_data, value);
114	if (retval)
115		return retval;
116
117	return count;
118}
119
120
121static const struct file_operations ulong_fops = {
122	.read		= ulong_read_file,
123	.write		= ulong_write_file,
124	.open		= simple_open,
125	.llseek		= default_llseek,
126};
127
128
129static const struct file_operations ulong_ro_fops = {
130	.read		= ulong_read_file,
131	.open		= simple_open,
132	.llseek		= default_llseek,
133};
134
135
136static int __oprofilefs_create_file(struct dentry *root, char const *name,
137	const struct file_operations *fops, int perm, void *priv)
138{
139	struct dentry *dentry;
140	struct inode *inode;
141
142	if (!root)
143		return -ENOMEM;
144
145	inode_lock(d_inode(root));
146	dentry = d_alloc_name(root, name);
147	if (!dentry) {
148		inode_unlock(d_inode(root));
149		return -ENOMEM;
150	}
151	inode = oprofilefs_get_inode(root->d_sb, S_IFREG | perm);
152	if (!inode) {
153		dput(dentry);
154		inode_unlock(d_inode(root));
155		return -ENOMEM;
156	}
157	inode->i_fop = fops;
158	inode->i_private = priv;
159	d_add(dentry, inode);
160	inode_unlock(d_inode(root));
161	return 0;
162}
163
164
165int oprofilefs_create_ulong(struct dentry *root,
166	char const *name, unsigned long *val)
167{
168	return __oprofilefs_create_file(root, name,
169					&ulong_fops, 0644, val);
170}
171
172
173int oprofilefs_create_ro_ulong(struct dentry *root,
174	char const *name, unsigned long *val)
175{
176	return __oprofilefs_create_file(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		= simple_open,
191	.llseek		= default_llseek,
192};
193
194
195int oprofilefs_create_ro_atomic(struct dentry *root,
196	char const *name, atomic_t *val)
197{
198	return __oprofilefs_create_file(root, name,
199					&atomic_ro_fops, 0444, val);
200}
201
202
203int oprofilefs_create_file(struct dentry *root,
204	char const *name, const struct file_operations *fops)
205{
206	return __oprofilefs_create_file(root, name, fops, 0644, NULL);
207}
208
209
210int oprofilefs_create_file_perm(struct dentry *root,
211	char const *name, const struct file_operations *fops, int perm)
212{
213	return __oprofilefs_create_file(root, name, fops, perm, NULL);
214}
215
216
217struct dentry *oprofilefs_mkdir(struct dentry *parent, char const *name)
218{
219	struct dentry *dentry;
220	struct inode *inode;
221
222	inode_lock(d_inode(parent));
223	dentry = d_alloc_name(parent, name);
224	if (!dentry) {
225		inode_unlock(d_inode(parent));
226		return NULL;
227	}
228	inode = oprofilefs_get_inode(parent->d_sb, S_IFDIR | 0755);
229	if (!inode) {
230		dput(dentry);
231		inode_unlock(d_inode(parent));
232		return NULL;
233	}
234	inode->i_op = &simple_dir_inode_operations;
235	inode->i_fop = &simple_dir_operations;
236	d_add(dentry, inode);
237	inode_unlock(d_inode(parent));
238	return dentry;
239}
240
241
242static int oprofilefs_fill_super(struct super_block *sb, struct fs_context *fc)
243{
244	struct inode *root_inode;
245
246	sb->s_blocksize = PAGE_SIZE;
247	sb->s_blocksize_bits = PAGE_SHIFT;
248	sb->s_magic = OPROFILEFS_MAGIC;
249	sb->s_op = &s_ops;
250	sb->s_time_gran = 1;
251
252	root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
253	if (!root_inode)
254		return -ENOMEM;
255	root_inode->i_op = &simple_dir_inode_operations;
256	root_inode->i_fop = &simple_dir_operations;
257	sb->s_root = d_make_root(root_inode);
258	if (!sb->s_root)
259		return -ENOMEM;
260
261	oprofile_create_files(sb->s_root);
262
263	// FIXME: verify kill_litter_super removes our dentries
264	return 0;
265}
266
267static int oprofilefs_get_tree(struct fs_context *fc)
268{
269	return get_tree_single(fc, oprofilefs_fill_super);
270}
271
272static const struct fs_context_operations oprofilefs_context_ops = {
273	.get_tree	= oprofilefs_get_tree,
274};
275
276static int oprofilefs_init_fs_context(struct fs_context *fc)
277{
278	fc->ops = &oprofilefs_context_ops;
279	return 0;
280}
281
282static struct file_system_type oprofilefs_type = {
283	.owner		= THIS_MODULE,
284	.name		= "oprofilefs",
285	.init_fs_context = oprofilefs_init_fs_context,
286	.kill_sb	= kill_litter_super,
287};
288MODULE_ALIAS_FS("oprofilefs");
289
290
291int __init oprofilefs_register(void)
292{
293	return register_filesystem(&oprofilefs_type);
294}
295
296
297void __exit oprofilefs_unregister(void)
298{
299	unregister_filesystem(&oprofilefs_type);
300}
301