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 spinlock_t oprofilefs_lock = SPIN_LOCK_UNLOCKED;
  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_mode = mode;
  32                 inode->i_uid = 0;
  33                 inode->i_gid = 0;
  34                 inode->i_blksize = PAGE_CACHE_SIZE;
  35                 inode->i_blocks = 0;
  36                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  37         }
  38         return inode;
  39 }
  40
  41
  42 static struct super_operations s_ops = {
  43         .statfs         = simple_statfs,
  44         .drop_inode     = generic_delete_inode,
  45 };
  46
  47
  48 ssize_t oprofilefs_str_to_user(char const * str, char __user * buf, size_t count, loff_t * offset)
  49 {
  50         size_t len = strlen(str);
  51
  52         if (!count)
  53                 return 0;
  54
  55         if (*offset > len)
  56                 return 0;
  57
  58         if (count > len - *offset)
  59                 count = len - *offset;
  60
  61         if (copy_to_user(buf, str + *offset, count))
  62                 return -EFAULT;
  63
  64         *offset += count;
  65
  66         return count;
  67 }
  68
  69
  70 #define TMPBUFSIZE 50
  71
  72 ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user * buf, size_t count, loff_t * offset)
  73 {
  74         char tmpbuf[TMPBUFSIZE];
  75         size_t maxlen;
  76
  77         if (!count)
  78                 return 0;
  79
  80         spin_lock(&oprofilefs_lock);
  81         maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
  82         spin_unlock(&oprofilefs_lock);
  83         if (maxlen > TMPBUFSIZE)
  84                 maxlen = TMPBUFSIZE;
  85
  86         if (*offset > maxlen)
  87                 return 0;
  88
  89         if (count > maxlen - *offset)
  90                 count = maxlen - *offset;
  91
  92         if (copy_to_user(buf, tmpbuf + *offset, count))
  93                 return -EFAULT;
  94
  95         *offset += count;
  96
  97         return count;
  98 }
  99
 100
 101 int oprofilefs_ulong_from_user(unsigned long * val, char const __user * buf, size_t count)
 102 {
 103         char tmpbuf[TMPBUFSIZE];
 104
 105         if (!count)
 106                 return 0;
 107
 108         if (count > TMPBUFSIZE - 1)
 109                 return -EINVAL;
 110
 111         memset(tmpbuf, 0x0, TMPBUFSIZE);
 112
 113         if (copy_from_user(tmpbuf, buf, count))
 114                 return -EFAULT;
 115
 116         spin_lock(&oprofilefs_lock);
 117         *val = simple_strtoul(tmpbuf, NULL, 0);
 118         spin_unlock(&oprofilefs_lock);
 119         return 0;
 120 }
 121
 122
 123 static ssize_t ulong_read_file(struct file * file, char __user * buf, size_t count, loff_t * offset)
 124 {
 125         unsigned long * val = file->private_data;
 126         return oprofilefs_ulong_to_user(*val, buf, count, offset);
 127 }
 128
 129
 130 static ssize_t ulong_write_file(struct file * file, char const __user * buf, size_t count, loff_t * offset)
 131 {
 132         unsigned long * value = file->private_data;
 133         int retval;
 134
 135         if (*offset)
 136                 return -EINVAL;
 137
 138         retval = oprofilefs_ulong_from_user(value, buf, count);
 139
 140         if (retval)
 141                 return retval;
 142         return count;
 143 }
 144
 145
 146 static int default_open(struct inode * inode, struct file * filp)
 147 {
 148         if (inode->u.generic_ip)
 149                 filp->private_data = inode->u.generic_ip;
 150         return 0;
 151 }
 152
 153
 154 static struct file_operations ulong_fops = {
 155         .read           = ulong_read_file,
 156         .write          = ulong_write_file,
 157         .open           = default_open,
 158 };
 159
 160
 161 static struct file_operations ulong_ro_fops = {
 162         .read           = ulong_read_file,
 163         .open           = default_open,
 164 };
 165
 166
 167 static struct dentry * __oprofilefs_create_file(struct super_block * sb,
 168         struct dentry * root, char const * name, struct file_operations * fops,
 169         int perm)
 170 {
 171         struct dentry * dentry;
 172         struct inode * inode;
 173         struct qstr qname;
 174         qname.name = name;
 175         qname.len = strlen(name);
 176         qname.hash = full_name_hash(qname.name, qname.len);
 177         dentry = d_alloc(root, &qname);
 178         if (!dentry)
 179                 return NULL;
 180         inode = oprofilefs_get_inode(sb, S_IFREG | perm);
 181         if (!inode) {
 182                 dput(dentry);
 183                 return NULL;
 184         }
 185         inode->i_fop = fops;
 186         d_add(dentry, inode);
 187         return dentry;
 188 }
 189
 190
 191 int oprofilefs_create_ulong(struct super_block * sb, struct dentry * root,
 192         char const * name, unsigned long * val)
 193 {
 194         struct dentry * d = __oprofilefs_create_file(sb, root, name,
 195                                                      &ulong_fops, 0644);
 196         if (!d)
 197                 return -EFAULT;
 198
 199         d->d_inode->u.generic_ip = val;
 200         return 0;
 201 }
 202
 203
 204 int oprofilefs_create_ro_ulong(struct super_block * sb, struct dentry * root,
 205         char const * name, unsigned long * val)
 206 {
 207         struct dentry * d = __oprofilefs_create_file(sb, root, name,
 208                                                      &ulong_ro_fops, 0444);
 209         if (!d)
 210                 return -EFAULT;
 211
 212         d->d_inode->u.generic_ip = val;
 213         return 0;
 214 }
 215
 216
 217 static ssize_t atomic_read_file(struct file * file, char __user * buf, size_t count, loff_t * offset)
 218 {
 219         atomic_t * val = file->private_data;
 220         return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
 221 }
 222
 223
 224 static struct file_operations atomic_ro_fops = {
 225         .read           = atomic_read_file,
 226         .open           = default_open,
 227 };
 228
 229
 230 int oprofilefs_create_ro_atomic(struct super_block * sb, struct dentry * root,
 231         char const * name, atomic_t * val)
 232 {
 233         struct dentry * d = __oprofilefs_create_file(sb, root, name,
 234                                                      &atomic_ro_fops, 0444);
 235         if (!d)
 236                 return -EFAULT;
 237
 238         d->d_inode->u.generic_ip = val;
 239         return 0;
 240 }
 241
 242
 243 int oprofilefs_create_file(struct super_block * sb, struct dentry * root,
 244         char const * name, struct file_operations * fops)
 245 {
 246         if (!__oprofilefs_create_file(sb, root, name, fops, 0644))
 247                 return -EFAULT;
 248         return 0;
 249 }
 250
 251
 252 int oprofilefs_create_file_perm(struct super_block * sb, struct dentry * root,
 253         char const * name, struct file_operations * fops, int perm)
 254 {
 255         if (!__oprofilefs_create_file(sb, root, name, fops, perm))
 256                 return -EFAULT;
 257         return 0;
 258 }
 259
 260
 261 struct dentry * oprofilefs_mkdir(struct super_block * sb,
 262         struct dentry * root, char const * name)
 263 {
 264         struct dentry * dentry;
 265         struct inode * inode;
 266         struct qstr qname;
 267         qname.name = name;
 268         qname.len = strlen(name);
 269         qname.hash = full_name_hash(qname.name, qname.len);
 270         dentry = d_alloc(root, &qname);
 271         if (!dentry)
 272                 return NULL;
 273         inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 274         if (!inode) {
 275                 dput(dentry);
 276                 return NULL;
 277         }
 278         inode->i_op = &simple_dir_inode_operations;
 279         inode->i_fop = &simple_dir_operations;
 280         d_add(dentry, inode);
 281         return dentry;
 282 }
 283
 284
 285 static int oprofilefs_fill_super(struct super_block * sb, void * data, int silent)
 286 {
 287         struct inode * root_inode;
 288         struct dentry * root_dentry;
 289
 290         sb->s_blocksize = PAGE_CACHE_SIZE;
 291         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 292         sb->s_magic = OPROFILEFS_MAGIC;
 293         sb->s_op = &s_ops;
 294
 295         root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 296         if (!root_inode)
 297                 return -ENOMEM;
 298         root_inode->i_op = &simple_dir_inode_operations;
 299         root_inode->i_fop = &simple_dir_operations;
 300         root_dentry = d_alloc_root(root_inode);
 301         if (!root_dentry) {
 302                 iput(root_inode);
 303                 return -ENOMEM;
 304         }
 305
 306         sb->s_root = root_dentry;
 307
 308         oprofile_create_files(sb, root_dentry);
 309
 310         // FIXME: verify kill_litter_super removes our dentries
 311         return 0;
 312 }
 313
 314
 315 static struct super_block *oprofilefs_get_sb(struct file_system_type *fs_type,
 316         int flags, const char *dev_name, void *data)
 317 {
 318         return get_sb_single(fs_type, flags, data, oprofilefs_fill_super);
 319 }
 320
 321
 322 static struct file_system_type oprofilefs_type = {
 323         .owner          = THIS_MODULE,
 324         .name           = "oprofilefs",
 325         .get_sb         = oprofilefs_get_sb,
 326         .kill_sb        = kill_litter_super,
 327 };
 328
 329
 330 int __init oprofilefs_register(void)
 331 {
 332         return register_filesystem(&oprofilefs_type);
 333 }
 334
 335
 336 void __exit oprofilefs_unregister(void)
 337 {
 338         unregister_filesystem(&oprofilefs_type);
 339 }