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         unsigned long flags;
  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_irqsave(&oprofilefs_lock, flags);
  82         *val = simple_strtoul(tmpbuf, NULL, 0);
  83         spin_unlock_irqrestore(&oprofilefs_lock, flags);
  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->i_private)
 114                 filp->private_data = inode->i_private;
 115         return 0;
 116 }
 117
 118
 119 static const struct file_operations ulong_fops = {
 120         .read           = ulong_read_file,
 121         .write          = ulong_write_file,
 122         .open           = default_open,
 123 };
 124
 125
 126 static const 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, const struct file_operations *fops,
 134         int perm)
 135 {
 136         struct dentry *dentry;
 137         struct inode *inode;
 138
 139         dentry = d_alloc_name(root, name);
 140         if (!dentry)
 141                 return NULL;
 142         inode = oprofilefs_get_inode(sb, S_IFREG | perm);
 143         if (!inode) {
 144                 dput(dentry);
 145                 return NULL;
 146         }
 147         inode->i_fop = fops;
 148         d_add(dentry, inode);
 149         return dentry;
 150 }
 151
 152
 153 int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
 154         char const *name, unsigned long *val)
 155 {
 156         struct dentry *d = __oprofilefs_create_file(sb, root, name,
 157                                                      &ulong_fops, 0644);
 158         if (!d)
 159                 return -EFAULT;
 160
 161         d->d_inode->i_private = val;
 162         return 0;
 163 }
 164
 165
 166 int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
 167         char const *name, unsigned long *val)
 168 {
 169         struct dentry *d = __oprofilefs_create_file(sb, root, name,
 170                                                      &ulong_ro_fops, 0444);
 171         if (!d)
 172                 return -EFAULT;
 173
 174         d->d_inode->i_private = val;
 175         return 0;
 176 }
 177
 178
 179 static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
 180 {
 181         atomic_t *val = file->private_data;
 182         return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
 183 }
 184
 185
 186 static const struct file_operations atomic_ro_fops = {
 187         .read           = atomic_read_file,
 188         .open           = default_open,
 189 };
 190
 191
 192 int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
 193         char const *name, atomic_t *val)
 194 {
 195         struct dentry *d = __oprofilefs_create_file(sb, root, name,
 196                                                      &atomic_ro_fops, 0444);
 197         if (!d)
 198                 return -EFAULT;
 199
 200         d->d_inode->i_private = val;
 201         return 0;
 202 }
 203
 204
 205 int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
 206         char const *name, const struct file_operations *fops)
 207 {
 208         if (!__oprofilefs_create_file(sb, root, name, fops, 0644))
 209                 return -EFAULT;
 210         return 0;
 211 }
 212
 213
 214 int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
 215         char const *name, const struct file_operations *fops, int perm)
 216 {
 217         if (!__oprofilefs_create_file(sb, root, name, fops, perm))
 218                 return -EFAULT;
 219         return 0;
 220 }
 221
 222
 223 struct dentry *oprofilefs_mkdir(struct super_block *sb,
 224         struct dentry *root, char const *name)
 225 {
 226         struct dentry *dentry;
 227         struct inode *inode;
 228
 229         dentry = d_alloc_name(root, name);
 230         if (!dentry)
 231                 return NULL;
 232         inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 233         if (!inode) {
 234                 dput(dentry);
 235                 return NULL;
 236         }
 237         inode->i_op = &simple_dir_inode_operations;
 238         inode->i_fop = &simple_dir_operations;
 239         d_add(dentry, inode);
 240         return dentry;
 241 }
 242
 243
 244 static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
 245 {
 246         struct inode *root_inode;
 247         struct dentry *root_dentry;
 248
 249         sb->s_blocksize = PAGE_CACHE_SIZE;
 250         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 251         sb->s_magic = OPROFILEFS_MAGIC;
 252         sb->s_op = &s_ops;
 253         sb->s_time_gran = 1;
 254
 255         root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 256         if (!root_inode)
 257                 return -ENOMEM;
 258         root_inode->i_op = &simple_dir_inode_operations;
 259         root_inode->i_fop = &simple_dir_operations;
 260         root_dentry = d_alloc_root(root_inode);
 261         if (!root_dentry) {
 262                 iput(root_inode);
 263                 return -ENOMEM;
 264         }
 265
 266         sb->s_root = root_dentry;
 267
 268         oprofile_create_files(sb, root_dentry);
 269
 270         // FIXME: verify kill_litter_super removes our dentries
 271         return 0;
 272 }
 273
 274
 275 static int oprofilefs_get_sb(struct file_system_type *fs_type,
 276         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 277 {
 278         return get_sb_single(fs_type, flags, data, oprofilefs_fill_super, mnt);
 279 }
 280
 281
 282 static struct file_system_type oprofilefs_type = {
 283         .owner          = THIS_MODULE,
 284         .name           = "oprofilefs",
 285         .get_sb         = oprofilefs_get_sb,
 286         .kill_sb        = kill_litter_super,
 287 };
 288
 289
 290 int __init oprofilefs_register(void)
 291 {
 292         return register_filesystem(&oprofilefs_type);
 293 }
 294
 295
 296 void __exit oprofilefs_unregister(void)
 297 {
 298         unregister_filesystem(&oprofilefs_type);
 299 }