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
  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;
  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 int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
  64 {
  65         char tmpbuf[TMPBUFSIZE];
  66         unsigned long flags;
  67
  68         if (!count)
  69                 return 0;
  70
  71         if (count > TMPBUFSIZE - 1)
  72                 return -EINVAL;
  73
  74         memset(tmpbuf, 0x0, TMPBUFSIZE);
  75
  76         if (copy_from_user(tmpbuf, buf, count))
  77                 return -EFAULT;
  78
  79         raw_spin_lock_irqsave(&oprofilefs_lock, flags);
  80         *val = simple_strtoul(tmpbuf, NULL, 0);
  81         raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);
  82         return 0;
  83 }
  84
  85
  86 static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
  87 {
  88         unsigned long *val = file->private_data;
  89         return oprofilefs_ulong_to_user(*val, buf, count, offset);
  90 }
  91
  92
  93 static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
  94 {
  95         unsigned long value;
  96         int retval;
  97
  98         if (*offset)
  99                 return -EINVAL;
 100
 101         retval = oprofilefs_ulong_from_user(&value, buf, count);
 102         if (retval)
 103                 return retval;
 104
 105         retval = oprofile_set_ulong(file->private_data, value);
 106         if (retval)
 107                 return retval;
 108
 109         return count;
 110 }
 111
 112
 113 static int default_open(struct inode *inode, struct file *filp)
 114 {
 115         if (inode->i_private)
 116                 filp->private_data = inode->i_private;
 117         return 0;
 118 }
 119
 120
 121 static const struct file_operations ulong_fops = {
 122         .read           = ulong_read_file,
 123         .write          = ulong_write_file,
 124         .open           = default_open,
 125         .llseek         = default_llseek,
 126 };
 127
 128
 129 static const struct file_operations ulong_ro_fops = {
 130         .read           = ulong_read_file,
 131         .open           = default_open,
 132         .llseek         = default_llseek,
 133 };
 134
 135
 136 static int __oprofilefs_create_file(struct super_block *sb,
 137         struct dentry *root, char const *name, const struct file_operations *fops,
 138         int perm, void *priv)
 139 {
 140         struct dentry *dentry;
 141         struct inode *inode;
 142
 143         dentry = d_alloc_name(root, name);
 144         if (!dentry)
 145                 return -ENOMEM;
 146         inode = oprofilefs_get_inode(sb, S_IFREG | perm);
 147         if (!inode) {
 148                 dput(dentry);
 149                 return -ENOMEM;
 150         }
 151         inode->i_fop = fops;
 152         d_add(dentry, inode);
 153         dentry->d_inode->i_private = priv;
 154         return 0;
 155 }
 156
 157
 158 int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
 159         char const *name, unsigned long *val)
 160 {
 161         return __oprofilefs_create_file(sb, root, name,
 162                                         &ulong_fops, 0644, val);
 163 }
 164
 165
 166 int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
 167         char const *name, unsigned long *val)
 168 {
 169         return __oprofilefs_create_file(sb, root, name,
 170                                         &ulong_ro_fops, 0444, val);
 171 }
 172
 173
 174 static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
 175 {
 176         atomic_t *val = file->private_data;
 177         return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
 178 }
 179
 180
 181 static const struct file_operations atomic_ro_fops = {
 182         .read           = atomic_read_file,
 183         .open           = default_open,
 184         .llseek         = default_llseek,
 185 };
 186
 187
 188 int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
 189         char const *name, atomic_t *val)
 190 {
 191         return __oprofilefs_create_file(sb, root, name,
 192                                         &atomic_ro_fops, 0444, val);
 193 }
 194
 195
 196 int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
 197         char const *name, const struct file_operations *fops)
 198 {
 199         return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
 200 }
 201
 202
 203 int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
 204         char const *name, const struct file_operations *fops, int perm)
 205 {
 206         return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
 207 }
 208
 209
 210 struct dentry *oprofilefs_mkdir(struct super_block *sb,
 211         struct dentry *root, char const *name)
 212 {
 213         struct dentry *dentry;
 214         struct inode *inode;
 215
 216         dentry = d_alloc_name(root, name);
 217         if (!dentry)
 218                 return NULL;
 219         inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 220         if (!inode) {
 221                 dput(dentry);
 222                 return NULL;
 223         }
 224         inode->i_op = &simple_dir_inode_operations;
 225         inode->i_fop = &simple_dir_operations;
 226         d_add(dentry, inode);
 227         return dentry;
 228 }
 229
 230
 231 static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
 232 {
 233         struct inode *root_inode;
 234         struct dentry *root_dentry;
 235
 236         sb->s_blocksize = PAGE_CACHE_SIZE;
 237         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 238         sb->s_magic = OPROFILEFS_MAGIC;
 239         sb->s_op = &s_ops;
 240         sb->s_time_gran = 1;
 241
 242         root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 243         if (!root_inode)
 244                 return -ENOMEM;
 245         root_inode->i_op = &simple_dir_inode_operations;
 246         root_inode->i_fop = &simple_dir_operations;
 247         root_dentry = d_alloc_root(root_inode);
 248         if (!root_dentry) {
 249                 iput(root_inode);
 250                 return -ENOMEM;
 251         }
 252
 253         sb->s_root = root_dentry;
 254
 255         oprofile_create_files(sb, root_dentry);
 256
 257         // FIXME: verify kill_litter_super removes our dentries
 258         return 0;
 259 }
 260
 261
 262 static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
 263         int flags, const char *dev_name, void *data)
 264 {
 265         return mount_single(fs_type, flags, data, oprofilefs_fill_super);
 266 }
 267
 268
 269 static struct file_system_type oprofilefs_type = {
 270         .owner          = THIS_MODULE,
 271         .name           = "oprofilefs",
 272         .mount          = oprofilefs_mount,
 273         .kill_sb        = kill_litter_super,
 274 };
 275
 276
 277 int __init oprofilefs_register(void)
 278 {
 279         return register_filesystem(&oprofilefs_type);
 280 }
 281
 282
 283 void __exit oprofilefs_unregister(void)
 284 {
 285         unregister_filesystem(&oprofilefs_type);
 286 }