| 1 | /* |
| 2 | * ltt-debugfs-abi.c |
| 3 | * |
| 4 | * Copyright 2010 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * LTTng debugfs ABI |
| 7 | * |
| 8 | * Mimic system calls for: |
| 9 | * - session creation, returns a file descriptor or failure. |
| 10 | * - channel creation, returns a file descriptor or failure. |
| 11 | * - Operates on a session file descriptor |
| 12 | * - Takes all channel options as parameters. |
| 13 | * - stream get, returns a file descriptor or failure. |
| 14 | * - Operates on a channel file descriptor. |
| 15 | * - stream notifier get, returns a file descriptor or failure. |
| 16 | * - Operates on a channel file descriptor. |
| 17 | * - event creation, returns a file descriptor or failure. |
| 18 | * - Operates on a channel file descriptor |
| 19 | * - Takes an event name as parameter |
| 20 | * - Takes an instrumentation source as parameter |
| 21 | * - e.g. tracepoints, dynamic_probes... |
| 22 | * - Takes instrumentation source specific arguments. |
| 23 | */ |
| 24 | |
| 25 | #include <linux/debugfs.h> |
| 26 | #include "ltt-events.h" |
| 27 | |
| 28 | /* |
| 29 | * This is LTTng's own personal way to create a system call as an external |
| 30 | * module. We use ioctl() on /sys/kernel/debug/lttng. |
| 31 | */ |
| 32 | |
| 33 | static struct dentry *lttng_dentry; |
| 34 | static const struct file_operations lttng_fops; |
| 35 | static const struct file_operations lttng_session_fops; |
| 36 | static const struct file_operations lttng_channel_fops; |
| 37 | |
| 38 | /* |
| 39 | * LTTng DebugFS ABI structures. |
| 40 | */ |
| 41 | |
| 42 | struct lttng_channel { |
| 43 | int overwrite; /* 1: overwrite, 0: discard */ |
| 44 | u64 subbuf_size; |
| 45 | u64 num_subbuf; |
| 46 | unsigned int switch_timer_interval; |
| 47 | unsigned int read_timer_interval; |
| 48 | }; |
| 49 | |
| 50 | struct lttng_event { |
| 51 | enum instrum_type itype; |
| 52 | char name[]; |
| 53 | }; |
| 54 | |
| 55 | static |
| 56 | int lttng_abi_create_session(void) |
| 57 | { |
| 58 | struct ltt_session *session; |
| 59 | struct file *session_filp; |
| 60 | int session_fd; |
| 61 | |
| 62 | session = ltt_session_create(); |
| 63 | if (!session) |
| 64 | return -ENOMEM; |
| 65 | session_fd = get_unused_fd_flags(O_RDWR); |
| 66 | if (session_fd < 0) { |
| 67 | ret = session_fd; |
| 68 | goto fd_error; |
| 69 | } |
| 70 | session_filp = anon_inode_getfile("[lttng_session]", |
| 71 | <tng_session_fops, |
| 72 | session, O_RDWR); |
| 73 | if (IS_ERR(session_filp)) { |
| 74 | ret = PTR_ERR(session_filp); |
| 75 | goto file_error; |
| 76 | } |
| 77 | fd_install(session_fd, session_filp); |
| 78 | return session_fd; |
| 79 | |
| 80 | file_error: |
| 81 | put_unused_fd(session_fd); |
| 82 | fd_error: |
| 83 | ltt_session_destroy(session); |
| 84 | return ret; |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * lttng_ioctl - lttng syscall through ioctl |
| 89 | * |
| 90 | * @filp: the file |
| 91 | * @cmd: the command |
| 92 | * @arg: command arg |
| 93 | * |
| 94 | * This ioctl implements lttng commands: |
| 95 | * LTTNG_SESSION |
| 96 | * Returns a LTTng trace session file descriptor |
| 97 | * |
| 98 | * The returned session will be deleted when its file descriptor is closed. |
| 99 | */ |
| 100 | static |
| 101 | long lttng_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 102 | { |
| 103 | switch (cmd) { |
| 104 | case LTTNG_SESSION: |
| 105 | return lttng_abi_create_session(); |
| 106 | default: |
| 107 | return -ENOIOCTLCMD; |
| 108 | } |
| 109 | } |
| 110 | |
| 111 | static const struct file_operations lttng_fops = { |
| 112 | .unlocked_ioctl = lttng_ioctl, |
| 113 | #ifdef CONFIG_COMPAT |
| 114 | .compat_ioctl = lttng_ioctl, |
| 115 | #endif |
| 116 | } |
| 117 | |
| 118 | int lttng_abi_create_channel(struct file *session_filp, |
| 119 | struct lttng_channel __user *uchan_param) |
| 120 | { |
| 121 | struct ltt_session *session = session_filp->private_data; |
| 122 | struct ltt_channel *chan; |
| 123 | struct file *chan_filp; |
| 124 | struct lttng_channel chan_param; |
| 125 | int chan_fd; |
| 126 | int ret = 0; |
| 127 | |
| 128 | if (copy_from_user(&chan_param, uchan_param, sizeof(chan_param))) |
| 129 | return -EFAULT; |
| 130 | chan_fd = get_unused_fd_flags(O_RDWR); |
| 131 | if (chan_fd < 0) { |
| 132 | ret = chan_fd; |
| 133 | goto fd_error; |
| 134 | } |
| 135 | chan_filp = anon_inode_getfile("[lttng_channel]", |
| 136 | <tng_channel_fops, |
| 137 | NULL, O_RDWR); |
| 138 | if (IS_ERR(chan_filp)) { |
| 139 | ret = PTR_ERR(chan_filp); |
| 140 | goto file_error; |
| 141 | } |
| 142 | /* |
| 143 | * We tolerate no failure path after channel creation. It will stay |
| 144 | * invariant for the rest of the session. |
| 145 | */ |
| 146 | chan = ltt_channel_create(session, chan_param->overwrite, NULL, |
| 147 | chan_param->subbuf_size, |
| 148 | chan_param->num_subbuf, |
| 149 | chan_param->switch_timer_interval, |
| 150 | chan_param->read_timer_interval); |
| 151 | if (!chan) { |
| 152 | ret = -ENOMEM; |
| 153 | goto chan_error; |
| 154 | } |
| 155 | chan_filp->private_data = chan; |
| 156 | fd_install(chan_fd, chan_filp); |
| 157 | /* The channel created holds a reference on the session */ |
| 158 | atomic_inc(&session_filp->f_count); |
| 159 | |
| 160 | return chan_fd; |
| 161 | |
| 162 | chan_error: |
| 163 | fput(chan_filp); |
| 164 | file_error: |
| 165 | put_unused_fd(chan_fd); |
| 166 | fd_error: |
| 167 | return ret; |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * lttng_session_ioctl - lttng session fd ioctl |
| 172 | * |
| 173 | * @filp: the file |
| 174 | * @cmd: the command |
| 175 | * @arg: command arg |
| 176 | * |
| 177 | * This ioctl implements lttng commands: |
| 178 | * LTTNG_CHANNEL |
| 179 | * Returns a LTTng channel file descriptor |
| 180 | * |
| 181 | * The returned channel will be deleted when its file descriptor is closed. |
| 182 | */ |
| 183 | static |
| 184 | long lttng_session_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 185 | { |
| 186 | switch (cmd) { |
| 187 | case LTTNG_CHANNEL: |
| 188 | return lttng_abi_create_channel(filp, (struct lttng_channel __user *)arg); |
| 189 | default: |
| 190 | return -ENOIOCTLCMD; |
| 191 | } |
| 192 | } |
| 193 | |
| 194 | /* |
| 195 | * Called when the last file reference is dropped. |
| 196 | * |
| 197 | * Big fat note: channels and events are invariant for the whole session after |
| 198 | * their creation. So this session destruction also destroys all channel and |
| 199 | * event structures specific to this session (they are not destroyed when their |
| 200 | * individual file is released). |
| 201 | */ |
| 202 | static |
| 203 | int lttng_session_release(struct inode *inode, struct file *file) |
| 204 | { |
| 205 | struct ltt_session *session = file->private_data; |
| 206 | return ltt_session_destroy(session); |
| 207 | } |
| 208 | |
| 209 | static const struct file_operations lttng_session_fops = { |
| 210 | .release = lttng_session_release, |
| 211 | .unlocked_ioctl = lttng_session_ioctl, |
| 212 | #ifdef CONFIG_COMPAT |
| 213 | .compat_ioctl = lttng_session_ioctl, |
| 214 | #endif |
| 215 | } |
| 216 | |
| 217 | static |
| 218 | int lttng_abi_open_stream(struct file *channel_filp) |
| 219 | { |
| 220 | struct ltt_channel *channel = channel_filp->private_data; |
| 221 | struct lib_ring_buffer *buf; |
| 222 | int stream_fd, ret; |
| 223 | |
| 224 | buf = ltt_buffer_read_open(channel->chan); |
| 225 | if (!buf) |
| 226 | return -ENOENT; |
| 227 | |
| 228 | stream_fd = get_unused_fd_flags(O_RDWR); |
| 229 | if (stream_fd < 0) { |
| 230 | ret = stream_fd; |
| 231 | goto fd_error; |
| 232 | } |
| 233 | stream_filp = anon_inode_getfile("[lttng_stream]", |
| 234 | &lib_ring_buffer_file_operations, |
| 235 | buf, O_RDWR); |
| 236 | if (IS_ERR(stream_filp)) { |
| 237 | ret = PTR_ERR(stream_filp); |
| 238 | goto file_error; |
| 239 | } |
| 240 | fd_install(stream_fd, stream_filp); |
| 241 | /* The stream holds a reference on the channel */ |
| 242 | atomic_inc(&channel_filp->f_count); |
| 243 | return stream_fd; |
| 244 | |
| 245 | file_error: |
| 246 | put_unused_fd(stream_fd); |
| 247 | fd_error: |
| 248 | ltt_buffer_read_close(buf); |
| 249 | return ret; |
| 250 | } |
| 251 | |
| 252 | static |
| 253 | int lttng_abi_create_event(struct file *channel_filp, |
| 254 | struct lttng_event __user *uevent_param) |
| 255 | { |
| 256 | struct ltt_channel *channel = channel_filp->private_data; |
| 257 | struct ltt_event *event; |
| 258 | char *event_name; |
| 259 | struct lttng_event event_param; |
| 260 | int event_fd, ret; |
| 261 | |
| 262 | if (copy_from_user(&event_param, uevent_param, sizeof(event_param))) |
| 263 | return -EFAULT; |
| 264 | event_name = kmalloc(PATH_MAX, GFP_KERNEL); |
| 265 | if (!event_name) |
| 266 | return -ENOMEM; |
| 267 | if (strncpy_from_user(event_name, &uevent_param->name, PATH_MAX)) { |
| 268 | ret = -EFAULT; |
| 269 | goto name_error; |
| 270 | } |
| 271 | event_name[PATH_MAX - 1] = '\0'; |
| 272 | event_fd = get_unused_fd_flags(O_RDWR); |
| 273 | if (event_fd < 0) { |
| 274 | ret = event_fd; |
| 275 | goto fd_error; |
| 276 | } |
| 277 | event_filp = anon_inode_getfile("[lttng_event]", |
| 278 | <tng_event_fops, |
| 279 | NULL, O_RDWR); |
| 280 | if (IS_ERR(event_filp)) { |
| 281 | ret = PTR_ERR(event_filp); |
| 282 | goto file_error; |
| 283 | } |
| 284 | /* |
| 285 | * We tolerate no failure path after event creation. It will stay |
| 286 | * invariant for the rest of the session. |
| 287 | */ |
| 288 | event = ltt_event_create(channel, event_param->itype, event_name, NULL); |
| 289 | if (!event) { |
| 290 | goto event_error; |
| 291 | ret = -EEXIST; |
| 292 | } |
| 293 | event_filp->private_data = event; |
| 294 | fd_install(event_fd, event_filp); |
| 295 | /* The event holds a reference on the channel */ |
| 296 | atomic_inc(&channel_filp->f_count); |
| 297 | kfree(event_name); |
| 298 | return event_fd; |
| 299 | |
| 300 | event_error: |
| 301 | fput(event_filp); |
| 302 | file_error: |
| 303 | put_unused_fd(event_fd); |
| 304 | fd_error: |
| 305 | name_error: |
| 306 | kfree(event_name); |
| 307 | return ret; |
| 308 | } |
| 309 | |
| 310 | /** |
| 311 | * lttng_channel_ioctl - lttng syscall through ioctl |
| 312 | * |
| 313 | * @filp: the file |
| 314 | * @cmd: the command |
| 315 | * @arg: command arg |
| 316 | * |
| 317 | * This ioctl implements lttng commands: |
| 318 | * LTTNG_STREAM |
| 319 | * Returns an event stream file descriptor or failure. |
| 320 | * (typically, one event stream records events from one CPU) |
| 321 | * LTTNG_EVENT |
| 322 | * Returns an event file descriptor or failure. |
| 323 | * |
| 324 | * The returned session will be deleted when its file descriptor is closed. |
| 325 | * Channel and event file descriptors also hold a reference on the session. |
| 326 | */ |
| 327 | static |
| 328 | long lttng_channel_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 329 | { |
| 330 | switch (cmd) { |
| 331 | case LTTNG_STREAM: |
| 332 | return lttng_abi_open_stream(filp); |
| 333 | case LTTNG_EVENT: |
| 334 | return lttng_abi_create_event(filp, (struct lttng_event __user *)arg); |
| 335 | default: |
| 336 | return -ENOIOCTLCMD; |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | /** |
| 341 | * lttng_channel_poll - lttng stream addition/removal monitoring |
| 342 | * |
| 343 | * @filp: the file |
| 344 | * @wait: poll table |
| 345 | */ |
| 346 | unsigned int lttng_channel_poll(struct file *filp, poll_table *wait) |
| 347 | { |
| 348 | struct ltt_channel *channel = filp->private_data; |
| 349 | unsigned int mask = 0; |
| 350 | |
| 351 | if (filp->f_mode & FMODE_READ) { |
| 352 | poll_wait_set_exclusive(wait); |
| 353 | poll_wait(filp, &channel->notify_wait, wait); |
| 354 | |
| 355 | /* TODO: identify when the channel is being finalized. */ |
| 356 | if (finalized) |
| 357 | return POLLHUP; |
| 358 | else |
| 359 | return POLLIN | POLLRDNORM; |
| 360 | } |
| 361 | return mask; |
| 362 | |
| 363 | } |
| 364 | |
| 365 | static const struct file_operations lttng_channel_fops = { |
| 366 | .release = lttng_channel_release, |
| 367 | .poll = lttng_channel_poll, |
| 368 | .unlocked_ioctl = lttng_channel_ioctl, |
| 369 | #ifdef CONFIG_COMPAT |
| 370 | .compat_ioctl = lttng_channel_ioctl, |
| 371 | #endif |
| 372 | } |
| 373 | |
| 374 | static int __init ltt_debugfs_abi_init(void) |
| 375 | { |
| 376 | int ret = 0; |
| 377 | |
| 378 | lttng_dentry = debugfs_create_file("lttng", NULL); |
| 379 | if (IS_ERR(lttng_dentry) || !lttng_dentry) |
| 380 | printk(KERN_ERR "Error creating LTTng control file\n"); |
| 381 | ret = -ENOMEM; |
| 382 | goto error; |
| 383 | } |
| 384 | error: |
| 385 | return ret; |
| 386 | } |
| 387 | |
| 388 | static void __exit ltt_debugfs_abi_exit(void) |
| 389 | { |
| 390 | debugfs_remote(lttng_dentry); |
| 391 | } |