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 const 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;
  95         int retval;
  96
  97         if (*offset)
  98                 return -EINVAL;
  99
 100         retval = oprofilefs_ulong_from_user(&value, buf, count);
 101         if (retval)
 102                 return retval;
 103
 104         retval = oprofile_set_ulong(file->private_data, value);
 105         if (retval)
 106                 return retval;
 107
 108         return count;
 109 }
 110
 111
 112 static int default_open(struct inode *inode, struct file *filp)
 113 {
 114         if (inode->i_private)
 115                 filp->private_data = inode->i_private;
 116         return 0;
 117 }
 118
 119
 120 static const struct file_operations ulong_fops = {
 121         .read           = ulong_read_file,
 122         .write          = ulong_write_file,
 123         .open           = default_open,
 124 };
 125
 126
 127 static const struct file_operations ulong_ro_fops = {
 128         .read           = ulong_read_file,
 129         .open           = default_open,
 130 };
 131
 132
 133 static int __oprofilefs_create_file(struct super_block *sb,
 134         struct dentry *root, char const *name, const struct file_operations *fops,
 135         int perm, void *priv)
 136 {
 137         struct dentry *dentry;
 138         struct inode *inode;
 139
 140         dentry = d_alloc_name(root, name);
 141         if (!dentry)
 142                 return -ENOMEM;
 143         inode = oprofilefs_get_inode(sb, S_IFREG | perm);
 144         if (!inode) {
 145                 dput(dentry);
 146                 return -ENOMEM;
 147         }
 148         inode->i_fop = fops;
 149         d_add(dentry, inode);
 150         dentry->d_inode->i_private = priv;
 151         return 0;
 152 }
 153
 154
 155 int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
 156         char const *name, unsigned long *val)
 157 {
 158         return __oprofilefs_create_file(sb, root, name,
 159                                         &ulong_fops, 0644, val);
 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         return __oprofilefs_create_file(sb, root, name,
 167                                         &ulong_ro_fops, 0444, val);
 168 }
 169
 170
 171 static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
 172 {
 173         atomic_t *val = file->private_data;
 174         return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
 175 }
 176
 177
 178 static const struct file_operations atomic_ro_fops = {
 179         .read           = atomic_read_file,
 180         .open           = default_open,
 181 };
 182
 183
 184 int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
 185         char const *name, atomic_t *val)
 186 {
 187         return __oprofilefs_create_file(sb, root, name,
 188                                         &atomic_ro_fops, 0444, val);
 189 }
 190
 191
 192 int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
 193         char const *name, const struct file_operations *fops)
 194 {
 195         return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
 196 }
 197
 198
 199 int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
 200         char const *name, const struct file_operations *fops, int perm)
 201 {
 202         return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
 203 }
 204
 205
 206 struct dentry *oprofilefs_mkdir(struct super_block *sb,
 207         struct dentry *root, char const *name)
 208 {
 209         struct dentry *dentry;
 210         struct inode *inode;
 211
 212         dentry = d_alloc_name(root, name);
 213         if (!dentry)
 214                 return NULL;
 215         inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 216         if (!inode) {
 217                 dput(dentry);
 218                 return NULL;
 219         }
 220         inode->i_op = &simple_dir_inode_operations;
 221         inode->i_fop = &simple_dir_operations;
 222         d_add(dentry, inode);
 223         return dentry;
 224 }
 225
 226
 227 static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
 228 {
 229         struct inode *root_inode;
 230         struct dentry *root_dentry;
 231
 232         sb->s_blocksize = PAGE_CACHE_SIZE;
 233         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 234         sb->s_magic = OPROFILEFS_MAGIC;
 235         sb->s_op = &s_ops;
 236         sb->s_time_gran = 1;
 237
 238         root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 239         if (!root_inode)
 240                 return -ENOMEM;
 241         root_inode->i_op = &simple_dir_inode_operations;
 242         root_inode->i_fop = &simple_dir_operations;
 243         root_dentry = d_alloc_root(root_inode);
 244         if (!root_dentry) {
 245                 iput(root_inode);
 246                 return -ENOMEM;
 247         }
 248
 249         sb->s_root = root_dentry;
 250
 251         oprofile_create_files(sb, root_dentry);
 252
 253         // FIXME: verify kill_litter_super removes our dentries
 254         return 0;
 255 }
 256
 257
 258 static int oprofilefs_get_sb(struct file_system_type *fs_type,
 259         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 260 {
 261         return get_sb_single(fs_type, flags, data, oprofilefs_fill_super, mnt);
 262 }
 263
 264
 265 static struct file_system_type oprofilefs_type = {
 266         .owner          = THIS_MODULE,
 267         .name           = "oprofilefs",
 268         .get_sb         = oprofilefs_get_sb,
 269         .kill_sb        = kill_litter_super,
 270 };
 271
 272
 273 int __init oprofilefs_register(void)
 274 {
 275         return register_filesystem(&oprofilefs_type);
 276 }
 277
 278
 279 void __exit oprofilefs_unregister(void)
 280 {
 281         unregister_filesystem(&oprofilefs_type);
 282 }