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