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_RAW_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_ino = get_next_ino();
  32                 inode->i_mode = mode;
  33                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  34         }
  35         return inode;
  36 }
  37
  38
  39 static const struct super_operations s_ops = {
  40         .statfs         = simple_statfs,
  41         .drop_inode     = generic_delete_inode,
  42 };
  43
  44
  45 ssize_t oprofilefs_str_to_user(char const *str, char __user *buf, size_t count, loff_t *offset)
  46 {
  47         return simple_read_from_buffer(buf, count, offset, str, strlen(str));
  48 }
  49
  50
  51 #define TMPBUFSIZE 50
  52
  53 ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t count, loff_t *offset)
  54 {
  55         char tmpbuf[TMPBUFSIZE];
  56         size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
  57         if (maxlen > TMPBUFSIZE)
  58                 maxlen = TMPBUFSIZE;
  59         return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
  60 }
  61
  62
  63 /*
  64  * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
  65  * unchanged and might be uninitialized. This follows write syscall
  66  * implementation when count is zero: "If count is zero ... [and if]
  67  * no errors are detected, 0 will be returned without causing any
  68  * other effect." (man 2 write)
  69  */
  70 int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
  71 {
  72         char tmpbuf[TMPBUFSIZE];
  73         unsigned long flags;
  74
  75         if (!count)
  76                 return 0;
  77
  78         if (count > TMPBUFSIZE - 1)
  79                 return -EINVAL;
  80
  81         memset(tmpbuf, 0x0, TMPBUFSIZE);
  82
  83         if (copy_from_user(tmpbuf, buf, count))
  84                 return -EFAULT;
  85
  86         raw_spin_lock_irqsave(&oprofilefs_lock, flags);
  87         *val = simple_strtoul(tmpbuf, NULL, 0);
  88         raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);
  89         return count;
  90 }
  91
  92
  93 static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
  94 {
  95         unsigned long *val = file->private_data;
  96         return oprofilefs_ulong_to_user(*val, buf, count, offset);
  97 }
  98
  99
 100 static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
 101 {
 102         unsigned long value;
 103         int retval;
 104
 105         if (*offset)
 106                 return -EINVAL;
 107
 108         retval = oprofilefs_ulong_from_user(&value, buf, count);
 109         if (retval <= 0)
 110                 return retval;
 111
 112         retval = oprofile_set_ulong(file->private_data, value);
 113         if (retval)
 114                 return retval;
 115
 116         return count;
 117 }
 118
 119
 120 static const struct file_operations ulong_fops = {
 121         .read           = ulong_read_file,
 122         .write          = ulong_write_file,
 123         .open           = simple_open,
 124         .llseek         = default_llseek,
 125 };
 126
 127
 128 static const struct file_operations ulong_ro_fops = {
 129         .read           = ulong_read_file,
 130         .open           = simple_open,
 131         .llseek         = default_llseek,
 132 };
 133
 134
 135 static int __oprofilefs_create_file(struct super_block *sb,
 136         struct dentry *root, char const *name, const struct file_operations *fops,
 137         int perm, void *priv)
 138 {
 139         struct dentry *dentry;
 140         struct inode *inode;
 141
 142         dentry = d_alloc_name(root, name);
 143         if (!dentry)
 144                 return -ENOMEM;
 145         inode = oprofilefs_get_inode(sb, S_IFREG | perm);
 146         if (!inode) {
 147                 dput(dentry);
 148                 return -ENOMEM;
 149         }
 150         inode->i_fop = fops;
 151         d_add(dentry, inode);
 152         dentry->d_inode->i_private = priv;
 153         return 0;
 154 }
 155
 156
 157 int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
 158         char const *name, unsigned long *val)
 159 {
 160         return __oprofilefs_create_file(sb, root, name,
 161                                         &ulong_fops, 0644, val);
 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         return __oprofilefs_create_file(sb, root, name,
 169                                         &ulong_ro_fops, 0444, val);
 170 }
 171
 172
 173 static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
 174 {
 175         atomic_t *val = file->private_data;
 176         return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
 177 }
 178
 179
 180 static const struct file_operations atomic_ro_fops = {
 181         .read           = atomic_read_file,
 182         .open           = simple_open,
 183         .llseek         = default_llseek,
 184 };
 185
 186
 187 int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
 188         char const *name, atomic_t *val)
 189 {
 190         return __oprofilefs_create_file(sb, root, name,
 191                                         &atomic_ro_fops, 0444, val);
 192 }
 193
 194
 195 int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
 196         char const *name, const struct file_operations *fops)
 197 {
 198         return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
 199 }
 200
 201
 202 int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
 203         char const *name, const struct file_operations *fops, int perm)
 204 {
 205         return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
 206 }
 207
 208
 209 struct dentry *oprofilefs_mkdir(struct super_block *sb,
 210         struct dentry *root, char const *name)
 211 {
 212         struct dentry *dentry;
 213         struct inode *inode;
 214
 215         dentry = d_alloc_name(root, name);
 216         if (!dentry)
 217                 return NULL;
 218         inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 219         if (!inode) {
 220                 dput(dentry);
 221                 return NULL;
 222         }
 223         inode->i_op = &simple_dir_inode_operations;
 224         inode->i_fop = &simple_dir_operations;
 225         d_add(dentry, inode);
 226         return dentry;
 227 }
 228
 229
 230 static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
 231 {
 232         struct inode *root_inode;
 233
 234         sb->s_blocksize = PAGE_CACHE_SIZE;
 235         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 236         sb->s_magic = OPROFILEFS_MAGIC;
 237         sb->s_op = &s_ops;
 238         sb->s_time_gran = 1;
 239
 240         root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
 241         if (!root_inode)
 242                 return -ENOMEM;
 243         root_inode->i_op = &simple_dir_inode_operations;
 244         root_inode->i_fop = &simple_dir_operations;
 245         sb->s_root = d_make_root(root_inode);
 246         if (!sb->s_root)
 247                 return -ENOMEM;
 248
 249         oprofile_create_files(sb, sb->s_root);
 250
 251         // FIXME: verify kill_litter_super removes our dentries
 252         return 0;
 253 }
 254
 255
 256 static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
 257         int flags, const char *dev_name, void *data)
 258 {
 259         return mount_single(fs_type, flags, data, oprofilefs_fill_super);
 260 }
 261
 262
 263 static struct file_system_type oprofilefs_type = {
 264         .owner          = THIS_MODULE,
 265         .name           = "oprofilefs",
 266         .mount          = oprofilefs_mount,
 267         .kill_sb        = kill_litter_super,
 268 };
 269
 270
 271 int __init oprofilefs_register(void)
 272 {
 273         return register_filesystem(&oprofilefs_type);
 274 }
 275
 276
 277 void __exit oprofilefs_unregister(void)
 278 {
 279         unregister_filesystem(&oprofilefs_type);
 280 }