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