| 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 session; /* Session file descriptor */ |
| 44 | int overwrite; /* 1: overwrite, 0: discard */ |
| 45 | u64 subbuf_size; |
| 46 | u64 num_subbuf; |
| 47 | unsigned int switch_timer_interval; |
| 48 | unsigned int read_timer_interval; |
| 49 | }; |
| 50 | |
| 51 | struct lttng_event { |
| 52 | int channel; /* Channel file descriptor */ |
| 53 | enum instrum_type itype; |
| 54 | char name[]; |
| 55 | }; |
| 56 | |
| 57 | static |
| 58 | int lttng_abi_create_session(void) |
| 59 | { |
| 60 | struct ltt_session *session; |
| 61 | struct file *session_file; |
| 62 | int session_fd; |
| 63 | |
| 64 | session = ltt_session_create() |
| 65 | if (!session) |
| 66 | return -ENOMEM; |
| 67 | session_fd = get_unused_fd_flags(O_RDWR); |
| 68 | if (session_fd < 0) { |
| 69 | ret = session_fd; |
| 70 | goto fd_error; |
| 71 | } |
| 72 | session_file = anon_inode_getfile("[lttng_session]", |
| 73 | <tng_session_fops, |
| 74 | session, O_RDWR); |
| 75 | if (IS_ERR(session_file)) { |
| 76 | ret = PTR_ERR(session_file); |
| 77 | goto file_error; |
| 78 | } |
| 79 | fd_install(session_fd, session_file); |
| 80 | return session_fd; |
| 81 | |
| 82 | file_error: |
| 83 | put_unused_fd(session_fd); |
| 84 | fd_error: |
| 85 | ltt_session_destroy(session); |
| 86 | return ret; |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * lttng_ioctl - lttng syscall through ioctl |
| 91 | * |
| 92 | * @filp: the file |
| 93 | * @cmd: the command |
| 94 | * @arg: command arg |
| 95 | * |
| 96 | * This ioctl implements lttng commands: |
| 97 | * LTTNG_SESSION |
| 98 | * Returns a LTTng trace session file descriptor |
| 99 | * |
| 100 | * The returned session will be deleted when its file descriptor is closed. |
| 101 | */ |
| 102 | static |
| 103 | long lttng_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 104 | { |
| 105 | switch (cmd) { |
| 106 | case LTTNG_SESSION: |
| 107 | return lttng_abi_create_session(); |
| 108 | default: |
| 109 | return -ENOIOCTLCMD; |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | #ifdef CONFIG_COMPAT |
| 114 | static |
| 115 | long lttng_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 116 | { |
| 117 | switch (cmd) { |
| 118 | case LTTNG_SESSION: |
| 119 | return lttng_abi_create_session(); |
| 120 | default: |
| 121 | return -ENOIOCTLCMD; |
| 122 | } |
| 123 | } |
| 124 | #endif |
| 125 | |
| 126 | static const struct file_operations lttng_fops = { |
| 127 | .unlocked_ioctl = lttng_ioctl, |
| 128 | #ifdef CONFIG_COMPAT |
| 129 | .compat_ioctl = lttng_compat_ioctl, |
| 130 | #endif |
| 131 | } |
| 132 | |
| 133 | int lttng_abi_create_channel(struct file *session_filp, |
| 134 | struct lttng_channel __user *uchan_param) |
| 135 | { |
| 136 | struct ltt_session *session = session_filp->private_data; |
| 137 | struct ltt_channel *chan; |
| 138 | struct file *chan_filp; |
| 139 | struct lttng_channel chan_param; |
| 140 | int chan_fd; |
| 141 | int ret = 0; |
| 142 | |
| 143 | if (copy_from_user(&chan_param, ucham_param, sizeof(chan_param))) |
| 144 | return -EFAULT; |
| 145 | chan = ltt_channel_create(session, chan_param->overwrite, NULL, |
| 146 | chan_param->subbuf_size, |
| 147 | chan_param->num_subbuf, |
| 148 | chan_param->switch_timer_interval, |
| 149 | chan_param->read_timer_interval); |
| 150 | if (!chan) { |
| 151 | ret = -ENOMEM; |
| 152 | goto chan_error; |
| 153 | } |
| 154 | chan_fd = get_unused_fd_flags(O_RDWR); |
| 155 | if (chan_fd < 0) { |
| 156 | ret = chan_fd; |
| 157 | goto fd_error; |
| 158 | } |
| 159 | chan_filp = anon_inode_getfile("[lttng_channel]", |
| 160 | <tng_channel_fops, |
| 161 | chan, O_RDWR); |
| 162 | if (IS_ERR(chan_filp)) { |
| 163 | ret = PTR_ERR(chan_filp); |
| 164 | goto file_error; |
| 165 | } |
| 166 | |
| 167 | /* The channel created holds a reference on the session */ |
| 168 | atomic_inc(&session_filp->f_count); |
| 169 | |
| 170 | return chan_fd; |
| 171 | |
| 172 | file_error: |
| 173 | put_unused_fd(chan_fd); |
| 174 | fd_error: |
| 175 | ltt_channel_destroy(chan); |
| 176 | chan_error: |
| 177 | return ret; |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * lttng_session_ioctl - lttng session fd ioctl |
| 182 | * |
| 183 | * @filp: the file |
| 184 | * @cmd: the command |
| 185 | * @arg: command arg |
| 186 | * |
| 187 | * This ioctl implements lttng commands: |
| 188 | * LTTNG_CHANNEL |
| 189 | * Returns a LTTng channel file descriptor |
| 190 | * |
| 191 | * The returned channel will be deleted when its file descriptor is closed. |
| 192 | */ |
| 193 | static |
| 194 | long lttng_session_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 195 | { |
| 196 | switch (cmd) { |
| 197 | case LTTNG_CHANNEL: |
| 198 | return lttng_abi_create_channel(filp, (struct lttng_channel __user *)arg); |
| 199 | default: |
| 200 | return -ENOIOCTLCMD; |
| 201 | } |
| 202 | } |
| 203 | |
| 204 | #ifdef CONFIG_COMPAT |
| 205 | static |
| 206 | long lttng_session_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 207 | { |
| 208 | switch (cmd) { |
| 209 | case LTTNG_CHANNEL: |
| 210 | return lttng_abi_create_channel(filp, (struct lttng_channel __user *)arg); |
| 211 | default: |
| 212 | return -ENOIOCTLCMD; |
| 213 | } |
| 214 | } |
| 215 | #endif |
| 216 | |
| 217 | static const struct file_operations lttng_session_fops = { |
| 218 | .unlocked_ioctl = lttng_session_ioctl, |
| 219 | #ifdef CONFIG_COMPAT |
| 220 | .compat_ioctl = lttng_session_compat_ioctl, |
| 221 | #endif |
| 222 | } |
| 223 | |
| 224 | static |
| 225 | int lttng_abi_open_stream(struct file *channel_filp) |
| 226 | { |
| 227 | struct ltt_channel *channel = channel_filp->private_data; |
| 228 | struct lib_ring_buffer *buf; |
| 229 | int stream_fd, ret; |
| 230 | |
| 231 | buf = ltt_buffer_read_open(channel->chan); |
| 232 | if (!buf) |
| 233 | return -ENOENT; |
| 234 | |
| 235 | stream_fd = get_unused_fd_flags(O_RDWR); |
| 236 | if (stream_fd < 0) { |
| 237 | ret = stream_fd; |
| 238 | goto fd_error; |
| 239 | } |
| 240 | stream_filp = anon_inode_getfile("[lttng_stream]", |
| 241 | <tng_stream_fops, |
| 242 | buf, O_RDWR); |
| 243 | if (IS_ERR(stream_filp)) { |
| 244 | ret = PTR_ERR(stream_filp); |
| 245 | goto file_error; |
| 246 | } |
| 247 | |
| 248 | /* The stream holds a reference on the channel */ |
| 249 | atomic_inc(&channel_filp->f_count); |
| 250 | return stream_fd; |
| 251 | |
| 252 | file_error: |
| 253 | put_unused_fd(stream_fd); |
| 254 | fd_error: |
| 255 | ltt_buffer_read_close(buf); |
| 256 | return ret; |
| 257 | } |
| 258 | |
| 259 | |
| 260 | /** |
| 261 | * lttng_channel_ioctl - lttng syscall through ioctl |
| 262 | * |
| 263 | * @filp: the file |
| 264 | * @cmd: the command |
| 265 | * @arg: command arg |
| 266 | * |
| 267 | * This ioctl implements lttng commands: |
| 268 | * LTTNG_STREAM |
| 269 | * Returns an event stream file descriptor or failure. |
| 270 | * (typically, one event stream records events from one CPU) |
| 271 | * LTTNG_STREAM_NOTIFIER |
| 272 | * Returns a file descriptor that can be used to monitor |
| 273 | * addition/removal of streams to/from a channel. (e.g. notifier |
| 274 | * called on CPU hotplug). |
| 275 | * LTTNG_EVENT |
| 276 | * Returns an event file descriptor or failure. |
| 277 | * |
| 278 | * The returned session will be deleted when its file descriptor is closed. |
| 279 | * Channel and event file descriptors also hold a reference on the session. |
| 280 | */ |
| 281 | static |
| 282 | long lttng_channel_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 283 | { |
| 284 | switch (cmd) { |
| 285 | case LTTNG_STREAM: |
| 286 | return lttng_abi_open_stream(filp); |
| 287 | case LTTNG_STREAM_NOTIFIER: |
| 288 | return lttng_abi_open_stream_notifier(filp); |
| 289 | case LTTNG_EVENT: |
| 290 | return lttng_abi_create_event(filp, (struct lttng_event __user *)arg); |
| 291 | default: |
| 292 | return -ENOIOCTLCMD; |
| 293 | } |
| 294 | } |
| 295 | |
| 296 | #ifdef CONFIG_COMPAT |
| 297 | static |
| 298 | long lttng_channel_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
| 299 | { |
| 300 | switch (cmd) { |
| 301 | case LTTNG_STREAM: |
| 302 | return lttng_abi_get_stream(filp); |
| 303 | case LTTNG_STREAM_NOTIFIER: |
| 304 | return lttng_abi_get_stream_notifier(filp); |
| 305 | case LTTNG_EVENT: |
| 306 | return lttng_abi_create_event(filp, (struct lttng_event __user *)arg); |
| 307 | default: |
| 308 | return -ENOIOCTLCMD; |
| 309 | } |
| 310 | } |
| 311 | #endif |
| 312 | |
| 313 | static const struct file_operations lttng_channel_fops = { |
| 314 | .unlocked_ioctl = lttng_channel_ioctl, |
| 315 | #ifdef CONFIG_COMPAT |
| 316 | .compat_ioctl = lttng_channel_compat_ioctl, |
| 317 | #endif |
| 318 | } |
| 319 | |
| 320 | static int __init ltt_debugfs_abi_init(void) |
| 321 | { |
| 322 | int ret = 0; |
| 323 | |
| 324 | lttng_dentry = debugfs_create_file("lttng", NULL); |
| 325 | if (IS_ERR(lttng_dentry) || !lttng_dentry) |
| 326 | printk(KERN_ERR "Error creating LTTng control file\n"); |
| 327 | ret = -ENOMEM; |
| 328 | goto error; |
| 329 | } |
| 330 | error: |
| 331 | return ret; |
| 332 | } |
| 333 | |
| 334 | static void __exit ltt_debugfs_abi_exit(void) |
| 335 | { |
| 336 | debugfs_remote(lttng_dentry); |
| 337 | } |