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 * 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 * 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 * 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 * buf, size_t count, loff_t * offset)
 124 {
 125         return oprofilefs_ulong_to_user(file->private_data, buf, count, offset);
 126 }
 127
 128
 129 static ssize_t ulong_write_file(struct file * file, char const * buf, size_t count, loff_t * offset)
 130 {
 131         unsigned long * value = file->private_data;
 132         int retval;
 133
 134         if (*offset)
 135                 return -EINVAL;
 136
 137         retval = oprofilefs_ulong_from_user(value, buf, count);
 138
 139         if (retval)
 140                 return retval;
 141         return count;
 142 }
 143
 144
 145 static int default_open(struct inode * inode, struct file * filp)
 146 {
 147         if (inode->u.generic_ip)
 148                 filp->private_data = inode->u.generic_ip;
 149         return 0;
 150 }
 151
 152
 153 static struct file_operations ulong_fops = {
 154         .read           = ulong_read_file,
 155         .write          = ulong_write_file,
 156         .open           = default_open,
 157 };
 158
 159
 160 static struct file_operations ulong_ro_fops = {
 161         .read           = ulong_read_file,
 162         .open           = default_open,
 163 };
 164
 165
 166 static struct dentry * __oprofilefs_create_file(struct super_block * sb,
 167         struct dentry * root, char const * name, struct file_operations * fops)
 168 {
 169         struct dentry * dentry;
 170         struct inode * inode;
 171         struct qstr qname;
 172         qname.name = name;
 173         qname.len = strlen(name);
 174         qname.hash = full_name_hash(qname.name, qname.len);
 175         dentry = d_alloc(root, &qname);
 176         if (!dentry)
 177                 return 0;
 178         inode = oprofilefs_get_inode(sb, S_IFREG | 0644);
 179         if (!inode) {
 180                 dput(dentry);
 181                 return 0;
 182         }
 183         inode->i_fop = fops;
 184         d_add(dentry, inode);
 185         return dentry;
 186 }
 187
 188
 189 int oprofilefs_create_ulong(struct super_block * sb, struct dentry * root,
 190         char const * name, unsigned long * val)
 191 {
 192         struct dentry * d = __oprofilefs_create_file(sb, root, name, &ulong_fops);
 193         if (!d)
 194                 return -EFAULT;
 195
 196         d->d_inode->u.generic_ip = val;
 197         return 0;
 198 }
 199
 200
 201 int oprofilefs_create_ro_ulong(struct super_block * sb, struct dentry * root,
 202         char const * name, unsigned long * val)
 203 {
 204         struct dentry * d = __oprofilefs_create_file(sb, root, name, &ulong_ro_fops);
 205         if (!d)
 206                 return -EFAULT;
 207
 208         d->d_inode->u.generic_ip = val;
 209         return 0;
 210 }
 211
 212
 213 static ssize_t atomic_read_file(struct file * file, char * buf, size_t count, loff_t * offset)
 214 {
 215         atomic_t * aval = file->private_data;
 216         unsigned long val = atomic_read(aval);
 217         return oprofilefs_ulong_to_user(&val, buf, count, offset);
 218 }
 219
 220
 221 static struct file_operations atomic_ro_fops = {
 222         .read           = atomic_read_file,
 223         .open           = default_open,
 224 };
 225
 226
 227 int oprofilefs_create_ro_atomic(struct super_block * sb, struct dentry * root,
 228         char const * name, atomic_t * val)
 229 {
 230         struct dentry * d = __oprofilefs_create_file(sb, root, name, &atomic_ro_fops);
 231         if (!d)
 232                 return -EFAULT;
 233
 234         d->d_inode->u.generic_ip = val;
 235         return 0;
 236 }
 237
 238
 239 int oprofilefs_create_file(struct super_block * sb, struct dentry * root,
 240         char const * name, struct file_operations * fops)
 241 {
 242         if (!__oprofilefs_create_file(sb, root, name, fops))
 243                 return -EFAULT;
 244         return 0;
 245 }
 246
 247
 248 struct dentry * oprofilefs_mkdir(struct super_block * sb,
 249         struct dentry * root, char const * name)
 250 {
 251         struct dentry * dentry;
 252         struct inode * inode;
 253         struct qstr qname;
 254         qname.name = name;
 255         qname.len = strlen(name);
 256         qname.hash = full_name_hash(qname.name, qname.len);
 257         dentry = d_alloc(root, &qname);
 258         if (!dentry)
 259                 return 0;
 260         inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 261         if (!inode) {
 262                 dput(dentry);
 263                 return 0;
 264         }
 265         inode->i_op = &simple_dir_inode_operations;
 266         inode->i_fop = &simple_dir_operations;
 267         d_add(dentry, inode);
 268         return dentry;
 269 }
 270
 271
 272 static int oprofilefs_fill_super(struct super_block * sb, void * data, int silent)
 273 {
 274         struct inode * root_inode;
 275         struct dentry * root_dentry;
 276
 277         sb->s_blocksize = PAGE_CACHE_SIZE;
 278         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 279         sb->s_magic = OPROFILEFS_MAGIC;
 280         sb->s_op = &s_ops;
 281
 282         root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 283         if (!root_inode)
 284                 return -ENOMEM;
 285         root_inode->i_op = &simple_dir_inode_operations;
 286         root_inode->i_fop = &simple_dir_operations;
 287         root_dentry = d_alloc_root(root_inode);
 288         if (!root_dentry) {
 289                 iput(root_inode);
 290                 return -ENOMEM;
 291         }
 292
 293         sb->s_root = root_dentry;
 294
 295         oprofile_create_files(sb, root_dentry);
 296
 297         // FIXME: verify kill_litter_super removes our dentries
 298         return 0;
 299 }
 300
 301
 302 static struct super_block *oprofilefs_get_sb(struct file_system_type *fs_type,
 303         int flags, const char *dev_name, void *data)
 304 {
 305         return get_sb_single(fs_type, flags, data, oprofilefs_fill_super);
 306 }
 307
 308
 309 static struct file_system_type oprofilefs_type = {
 310         .owner          = THIS_MODULE,
 311         .name           = "oprofilefs",
 312         .get_sb         = oprofilefs_get_sb,
 313         .kill_sb        = kill_litter_super,
 314 };
 315
 316
 317 int __init oprofilefs_register(void)
 318 {
 319         return register_filesystem(&oprofilefs_type);
 320 }
 321
 322
 323 void __exit oprofilefs_unregister(void)
 324 {
 325         unregister_filesystem(&oprofilefs_type);
 326 }