| 1 | /* |
| 2 | * (C) Copyright 2009 - |
| 3 | * Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) |
| 4 | * |
| 5 | * LTTng kprobes integration module. |
| 6 | * |
| 7 | * Dual LGPL v2.1/GPL v2 license. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/kprobes.h> |
| 12 | #include <linux/marker.h> |
| 13 | #include <linux/mutex.h> |
| 14 | #include <linux/jhash.h> |
| 15 | #include <linux/seq_file.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/debugfs.h> |
| 18 | #include <linux/kallsyms.h> |
| 19 | |
| 20 | #include "ltt-type-serializer.h" |
| 21 | #include "ltt-tracer.h" |
| 22 | |
| 23 | #define LTT_KPROBES_DIR "kprobes" |
| 24 | #define LTT_KPROBES_ENABLE "enable" |
| 25 | #define LTT_KPROBES_DISABLE "disable" |
| 26 | #define LTT_KPROBES_LIST "list" |
| 27 | |
| 28 | /* Active LTTng kprobes hash table */ |
| 29 | static DEFINE_MUTEX(ltt_kprobes_mutex); |
| 30 | |
| 31 | #define LTT_KPROBE_HASH_BITS 6 |
| 32 | #define LTT_KPROBE_TABLE_SIZE (1 << LTT_KPROBE_HASH_BITS) |
| 33 | static struct hlist_head ltt_kprobe_table[LTT_KPROBE_TABLE_SIZE]; |
| 34 | |
| 35 | struct kprobe_entry { |
| 36 | struct hlist_node hlist; |
| 37 | struct kprobe kp; |
| 38 | char key[0]; |
| 39 | }; |
| 40 | |
| 41 | static struct dentry *ltt_kprobes_dir, |
| 42 | *ltt_kprobes_enable_dentry, |
| 43 | *ltt_kprobes_disable_dentry, |
| 44 | *ltt_kprobes_list_dentry; |
| 45 | |
| 46 | static int module_exit; |
| 47 | |
| 48 | |
| 49 | static void trace_kprobe_table_entry(void *call_data, struct kprobe_entry *e) |
| 50 | { |
| 51 | unsigned long addr; |
| 52 | char *namebuf = (char *)__get_free_page(GFP_KERNEL); |
| 53 | |
| 54 | if (e->kp.addr) { |
| 55 | sprint_symbol(namebuf, (unsigned long)e->kp.addr); |
| 56 | addr = (unsigned long)e->kp.addr; |
| 57 | } else { |
| 58 | strncpy(namebuf, e->kp.symbol_name, PAGE_SIZE - 1); |
| 59 | /* TODO : add offset */ |
| 60 | addr = kallsyms_lookup_name(namebuf); |
| 61 | } |
| 62 | if (addr) |
| 63 | __trace_mark(0, kprobe_state, kprobe_table, call_data, |
| 64 | "ip 0x%lX symbol %s", addr, namebuf); |
| 65 | free_page((unsigned long)namebuf); |
| 66 | } |
| 67 | |
| 68 | DEFINE_MARKER(kernel, kprobe, "ip %lX"); |
| 69 | |
| 70 | static int ltt_kprobe_handler_pre(struct kprobe *p, struct pt_regs *regs) |
| 71 | { |
| 72 | struct marker *marker; |
| 73 | unsigned long data; |
| 74 | |
| 75 | data = (unsigned long)p->addr; |
| 76 | marker = &GET_MARKER(kernel, kprobe); |
| 77 | ltt_specialized_trace(marker, marker->single.probe_private, |
| 78 | &data, sizeof(data), sizeof(data)); |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | static int ltt_register_kprobe(const char *key) |
| 83 | { |
| 84 | struct hlist_head *head; |
| 85 | struct hlist_node *node; |
| 86 | struct kprobe_entry *e = NULL; |
| 87 | char *symbol_name = NULL; |
| 88 | unsigned long addr; |
| 89 | unsigned int offset = 0; |
| 90 | u32 hash; |
| 91 | size_t key_len = strlen(key) + 1; |
| 92 | int ret; |
| 93 | |
| 94 | if (key_len == 1) |
| 95 | return -ENOENT; /* only \0 */ |
| 96 | |
| 97 | if (sscanf(key, "%li", &addr) != 1) |
| 98 | addr = 0; |
| 99 | |
| 100 | if (!addr) { |
| 101 | const char *symbol_end = NULL; |
| 102 | unsigned int symbol_len; /* includes final \0 */ |
| 103 | |
| 104 | symbol_end = strchr(key, ' '); |
| 105 | if (symbol_end) |
| 106 | symbol_len = symbol_end - key + 1; |
| 107 | else |
| 108 | symbol_len = key_len; |
| 109 | symbol_name = kmalloc(symbol_len, GFP_KERNEL); |
| 110 | if (!symbol_name) { |
| 111 | ret = -ENOMEM; |
| 112 | goto error; |
| 113 | } |
| 114 | memcpy(symbol_name, key, symbol_len - 1); |
| 115 | symbol_name[symbol_len-1] = '\0'; |
| 116 | if (symbol_end) { |
| 117 | symbol_end++; /* start of offset */ |
| 118 | if (sscanf(symbol_end, "%i", &offset) != 1) |
| 119 | offset = 0; |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | hash = jhash(key, key_len-1, 0); |
| 124 | head = <t_kprobe_table[hash & ((1 << LTT_KPROBE_HASH_BITS)-1)]; |
| 125 | hlist_for_each_entry(e, node, head, hlist) { |
| 126 | if (!strcmp(key, e->key)) { |
| 127 | printk(KERN_NOTICE "Kprobe %s busy\n", key); |
| 128 | ret = -EBUSY; |
| 129 | goto error; |
| 130 | } |
| 131 | } |
| 132 | /* |
| 133 | * Using kzalloc here to allocate a variable length element. Could |
| 134 | * cause some memory fragmentation if overused. |
| 135 | */ |
| 136 | e = kzalloc(sizeof(struct kprobe_entry) + key_len, GFP_KERNEL); |
| 137 | if (!e) { |
| 138 | ret = -ENOMEM; |
| 139 | goto error; |
| 140 | } |
| 141 | memcpy(e->key, key, key_len); |
| 142 | hlist_add_head(&e->hlist, head); |
| 143 | e->kp.pre_handler = ltt_kprobe_handler_pre; |
| 144 | e->kp.symbol_name = symbol_name; |
| 145 | e->kp.offset = offset; |
| 146 | e->kp.addr = (void *)addr; |
| 147 | ret = register_kprobe(&e->kp); |
| 148 | if (ret < 0) |
| 149 | goto error_list_del; |
| 150 | trace_kprobe_table_entry(NULL, e); |
| 151 | return 0; |
| 152 | |
| 153 | error_list_del: |
| 154 | hlist_del(&e->hlist); |
| 155 | error: |
| 156 | kfree(symbol_name); |
| 157 | kfree(e); |
| 158 | return ret; |
| 159 | } |
| 160 | |
| 161 | static int ltt_unregister_kprobe(const char *key) |
| 162 | { |
| 163 | struct hlist_head *head; |
| 164 | struct hlist_node *node; |
| 165 | struct kprobe_entry *e; |
| 166 | int found = 0; |
| 167 | size_t key_len = strlen(key) + 1; |
| 168 | u32 hash; |
| 169 | |
| 170 | hash = jhash(key, key_len-1, 0); |
| 171 | head = <t_kprobe_table[hash & ((1 << LTT_KPROBE_HASH_BITS)-1)]; |
| 172 | hlist_for_each_entry(e, node, head, hlist) { |
| 173 | if (!strcmp(key, e->key)) { |
| 174 | found = 1; |
| 175 | break; |
| 176 | } |
| 177 | } |
| 178 | if (!found) |
| 179 | return -ENOENT; |
| 180 | hlist_del(&e->hlist); |
| 181 | unregister_kprobe(&e->kp); |
| 182 | kfree(e->kp.symbol_name); |
| 183 | kfree(e); |
| 184 | return 0; |
| 185 | } |
| 186 | |
| 187 | static void ltt_unregister_all_kprobes(void) |
| 188 | { |
| 189 | struct kprobe_entry *e; |
| 190 | struct hlist_head *head; |
| 191 | struct hlist_node *node, *tmp; |
| 192 | unsigned int i; |
| 193 | |
| 194 | for (i = 0; i < LTT_KPROBE_TABLE_SIZE; i++) { |
| 195 | head = <t_kprobe_table[i]; |
| 196 | hlist_for_each_entry_safe(e, node, tmp, head, hlist) { |
| 197 | hlist_del(&e->hlist); |
| 198 | unregister_kprobe(&e->kp); |
| 199 | kfree(e->kp.symbol_name); |
| 200 | kfree(e); |
| 201 | } |
| 202 | } |
| 203 | } |
| 204 | |
| 205 | /* |
| 206 | * Allows to specify either |
| 207 | * - symbol |
| 208 | * - symbol offset |
| 209 | * - address |
| 210 | */ |
| 211 | static ssize_t enable_op_write(struct file *file, |
| 212 | const char __user *user_buf, size_t count, loff_t *ppos) |
| 213 | { |
| 214 | int err, buf_size; |
| 215 | char *end; |
| 216 | char *buf = (char *)__get_free_page(GFP_KERNEL); |
| 217 | |
| 218 | mutex_lock(<t_kprobes_mutex); |
| 219 | if (module_exit) { |
| 220 | err = -EPERM; |
| 221 | goto error; |
| 222 | } |
| 223 | |
| 224 | buf_size = min_t(size_t, count, PAGE_SIZE - 1); |
| 225 | err = copy_from_user(buf, user_buf, buf_size); |
| 226 | if (err) |
| 227 | goto error; |
| 228 | buf[buf_size] = '\0'; |
| 229 | end = strchr(buf, '\n'); |
| 230 | if (end) |
| 231 | *end = '\0'; |
| 232 | err = ltt_register_kprobe(buf); |
| 233 | if (err) |
| 234 | goto error; |
| 235 | |
| 236 | mutex_unlock(<t_kprobes_mutex); |
| 237 | free_page((unsigned long)buf); |
| 238 | return count; |
| 239 | error: |
| 240 | mutex_unlock(<t_kprobes_mutex); |
| 241 | free_page((unsigned long)buf); |
| 242 | return err; |
| 243 | } |
| 244 | |
| 245 | static const struct file_operations ltt_kprobes_enable = { |
| 246 | .write = enable_op_write, |
| 247 | }; |
| 248 | |
| 249 | static ssize_t disable_op_write(struct file *file, |
| 250 | const char __user *user_buf, size_t count, loff_t *ppos) |
| 251 | { |
| 252 | int err, buf_size; |
| 253 | char *end; |
| 254 | char *buf = (char *)__get_free_page(GFP_KERNEL); |
| 255 | |
| 256 | mutex_lock(<t_kprobes_mutex); |
| 257 | if (module_exit) |
| 258 | goto end; |
| 259 | |
| 260 | buf_size = min_t(size_t, count, PAGE_SIZE - 1); |
| 261 | err = copy_from_user(buf, user_buf, buf_size); |
| 262 | if (err) |
| 263 | goto error; |
| 264 | buf[buf_size] = '\0'; |
| 265 | end = strchr(buf, '\n'); |
| 266 | if (end) |
| 267 | *end = '\0'; |
| 268 | err = ltt_unregister_kprobe(buf); |
| 269 | if (err) |
| 270 | goto error; |
| 271 | end: |
| 272 | mutex_unlock(<t_kprobes_mutex); |
| 273 | free_page((unsigned long)buf); |
| 274 | return count; |
| 275 | error: |
| 276 | mutex_unlock(<t_kprobes_mutex); |
| 277 | free_page((unsigned long)buf); |
| 278 | return err; |
| 279 | } |
| 280 | |
| 281 | static const struct file_operations ltt_kprobes_disable = { |
| 282 | .write = disable_op_write, |
| 283 | }; |
| 284 | |
| 285 | /* |
| 286 | * This seqfile read is not perfectly safe, as a kprobe could be removed from |
| 287 | * the hash table between two reads. This will result in an incomplete output. |
| 288 | */ |
| 289 | static struct kprobe_entry *ltt_find_next_kprobe(struct kprobe_entry *prev) |
| 290 | { |
| 291 | struct kprobe_entry *e; |
| 292 | struct hlist_head *head; |
| 293 | struct hlist_node *node; |
| 294 | unsigned int i; |
| 295 | int found = 0; |
| 296 | |
| 297 | if (prev == (void *)-1UL) |
| 298 | return NULL; |
| 299 | |
| 300 | if (!prev) |
| 301 | found = 1; |
| 302 | |
| 303 | for (i = 0; i < LTT_KPROBE_TABLE_SIZE; i++) { |
| 304 | head = <t_kprobe_table[i]; |
| 305 | hlist_for_each_entry(e, node, head, hlist) { |
| 306 | if (found) |
| 307 | return e; |
| 308 | if (e == prev) |
| 309 | found = 1; |
| 310 | } |
| 311 | } |
| 312 | return NULL; |
| 313 | } |
| 314 | |
| 315 | static void *lk_next(struct seq_file *m, void *p, loff_t *pos) |
| 316 | { |
| 317 | m->private = ltt_find_next_kprobe(m->private); |
| 318 | if (!m->private) { |
| 319 | m->private = (void *)-1UL; |
| 320 | return NULL; |
| 321 | } |
| 322 | return m->private; |
| 323 | } |
| 324 | |
| 325 | static void *lk_start(struct seq_file *m, loff_t *pos) |
| 326 | { |
| 327 | mutex_lock(<t_kprobes_mutex); |
| 328 | if (!*pos) |
| 329 | m->private = NULL; |
| 330 | m->private = ltt_find_next_kprobe(m->private); |
| 331 | if (!m->private) { |
| 332 | m->private = (void *)-1UL; |
| 333 | return NULL; |
| 334 | } |
| 335 | return m->private; |
| 336 | } |
| 337 | |
| 338 | static void lk_stop(struct seq_file *m, void *p) |
| 339 | { |
| 340 | mutex_unlock(<t_kprobes_mutex); |
| 341 | } |
| 342 | |
| 343 | static int lk_show(struct seq_file *m, void *p) |
| 344 | { |
| 345 | struct kprobe_entry *e = m->private; |
| 346 | seq_printf(m, "%s\n", e->key); |
| 347 | return 0; |
| 348 | } |
| 349 | |
| 350 | static const struct seq_operations ltt_kprobes_list_op = { |
| 351 | .start = lk_start, |
| 352 | .next = lk_next, |
| 353 | .stop = lk_stop, |
| 354 | .show = lk_show, |
| 355 | }; |
| 356 | |
| 357 | static int ltt_kprobes_list_open(struct inode *inode, struct file *file) |
| 358 | { |
| 359 | int ret; |
| 360 | |
| 361 | ret = seq_open(file, <t_kprobes_list_op); |
| 362 | if (ret == 0) |
| 363 | ((struct seq_file *)file->private_data)->private = NULL; |
| 364 | return ret; |
| 365 | } |
| 366 | |
| 367 | static int ltt_kprobes_list_release(struct inode *inode, struct file *file) |
| 368 | { |
| 369 | struct seq_file *seq = file->private_data; |
| 370 | |
| 371 | seq->private = NULL; |
| 372 | return seq_release(inode, file); |
| 373 | } |
| 374 | |
| 375 | static const struct file_operations ltt_kprobes_list = { |
| 376 | .open = ltt_kprobes_list_open, |
| 377 | .read = seq_read, |
| 378 | .llseek = seq_lseek, |
| 379 | .release = ltt_kprobes_list_release, |
| 380 | }; |
| 381 | |
| 382 | /* |
| 383 | * kprobes table dump. Callback invoked by ltt-statedump. ltt-statedump must |
| 384 | * take a reference to this module before calling this callback. |
| 385 | */ |
| 386 | void ltt_dump_kprobes_table(void *call_data) |
| 387 | { |
| 388 | struct kprobe_entry *e; |
| 389 | struct hlist_head *head; |
| 390 | struct hlist_node *node; |
| 391 | unsigned int i; |
| 392 | |
| 393 | for (i = 0; i < LTT_KPROBE_TABLE_SIZE; i++) { |
| 394 | head = <t_kprobe_table[i]; |
| 395 | hlist_for_each_entry(e, node, head, hlist) |
| 396 | trace_kprobe_table_entry(call_data, e); |
| 397 | } |
| 398 | } |
| 399 | EXPORT_SYMBOL_GPL(ltt_dump_kprobes_table); |
| 400 | |
| 401 | static int __init ltt_kprobes_init(void) |
| 402 | { |
| 403 | struct dentry *ltt_root_dentry; |
| 404 | int ret = 0; |
| 405 | |
| 406 | printk(KERN_INFO "LTT : ltt-kprobes init\n"); |
| 407 | mutex_lock(<t_kprobes_mutex); |
| 408 | |
| 409 | ltt_root_dentry = get_ltt_root(); |
| 410 | if (!ltt_root_dentry) { |
| 411 | ret = -ENOENT; |
| 412 | goto err_no_root; |
| 413 | } |
| 414 | |
| 415 | ltt_kprobes_dir = debugfs_create_dir(LTT_KPROBES_DIR, ltt_root_dentry); |
| 416 | if (!ltt_kprobes_dir) { |
| 417 | printk(KERN_ERR |
| 418 | "ltt_kprobes_init: failed to create dir %s\n", |
| 419 | LTT_KPROBES_DIR); |
| 420 | ret = -ENOMEM; |
| 421 | goto err_no_dir; |
| 422 | } |
| 423 | |
| 424 | ltt_kprobes_enable_dentry = debugfs_create_file(LTT_KPROBES_ENABLE, |
| 425 | S_IWUSR, |
| 426 | ltt_kprobes_dir, NULL, |
| 427 | <t_kprobes_enable); |
| 428 | if (IS_ERR(ltt_kprobes_enable_dentry) || !ltt_kprobes_enable_dentry) { |
| 429 | printk(KERN_ERR |
| 430 | "ltt_kprobes_init: failed to create file %s\n", |
| 431 | LTT_KPROBES_ENABLE); |
| 432 | ret = -ENOMEM; |
| 433 | goto err_no_enable; |
| 434 | } |
| 435 | |
| 436 | ltt_kprobes_disable_dentry = debugfs_create_file(LTT_KPROBES_DISABLE, |
| 437 | S_IWUSR, |
| 438 | ltt_kprobes_dir, NULL, |
| 439 | <t_kprobes_disable); |
| 440 | if (IS_ERR(ltt_kprobes_disable_dentry) || !ltt_kprobes_disable_dentry) { |
| 441 | printk(KERN_ERR |
| 442 | "ltt_kprobes_init: failed to create file %s\n", |
| 443 | LTT_KPROBES_DISABLE); |
| 444 | ret = -ENOMEM; |
| 445 | goto err_no_disable; |
| 446 | } |
| 447 | |
| 448 | ltt_kprobes_list_dentry = debugfs_create_file(LTT_KPROBES_LIST, |
| 449 | S_IWUSR, ltt_kprobes_dir, |
| 450 | NULL, <t_kprobes_list); |
| 451 | if (IS_ERR(ltt_kprobes_list_dentry) || !ltt_kprobes_list_dentry) { |
| 452 | printk(KERN_ERR |
| 453 | "ltt_kprobes_init: failed to create file %s\n", |
| 454 | LTT_KPROBES_LIST); |
| 455 | ret = -ENOMEM; |
| 456 | goto err_no_list; |
| 457 | } |
| 458 | ltt_statedump_register_kprobes_dump(ltt_dump_kprobes_table); |
| 459 | |
| 460 | mutex_unlock(<t_kprobes_mutex); |
| 461 | return ret; |
| 462 | |
| 463 | err_no_list: |
| 464 | debugfs_remove(ltt_kprobes_disable_dentry); |
| 465 | err_no_disable: |
| 466 | debugfs_remove(ltt_kprobes_enable_dentry); |
| 467 | err_no_enable: |
| 468 | debugfs_remove(ltt_kprobes_dir); |
| 469 | err_no_dir: |
| 470 | err_no_root: |
| 471 | mutex_unlock(<t_kprobes_mutex); |
| 472 | return ret; |
| 473 | } |
| 474 | module_init(ltt_kprobes_init); |
| 475 | |
| 476 | static void __exit ltt_kprobes_exit(void) |
| 477 | { |
| 478 | printk(KERN_INFO "LTT : ltt-kprobes exit\n"); |
| 479 | mutex_lock(<t_kprobes_mutex); |
| 480 | module_exit = 1; |
| 481 | ltt_statedump_unregister_kprobes_dump(ltt_dump_kprobes_table); |
| 482 | debugfs_remove(ltt_kprobes_list_dentry); |
| 483 | debugfs_remove(ltt_kprobes_disable_dentry); |
| 484 | debugfs_remove(ltt_kprobes_enable_dentry); |
| 485 | debugfs_remove(ltt_kprobes_dir); |
| 486 | ltt_unregister_all_kprobes(); |
| 487 | mutex_unlock(<t_kprobes_mutex); |
| 488 | } |
| 489 | module_exit(ltt_kprobes_exit); |
| 490 | |
| 491 | MODULE_LICENSE("GPL and additional rights"); |
| 492 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 493 | MODULE_DESCRIPTION("Linux Trace Toolkit Kprobes Support"); |