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