1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 * 21 * Portions Copyright 2006-2008 John Birrell jb@freebsd.org 22 * 23 * $FreeBSD: head/sys/cddl/dev/sdt/sdt.c 285703 2015-07-19 22:14:09Z markj $ 24 * 25 */ 26 27 /* 28 * This file contains a reimplementation of the statically-defined tracing (SDT) 29 * framework for DTrace. Probes and SDT providers are defined using the macros 30 * in sys/sdt.h, which append all the needed structures to linker sets. When 31 * this module is loaded, it iterates over all of the loaded modules and 32 * registers probes and providers with the DTrace framework based on the 33 * contents of these linker sets. 34 * 35 * A list of SDT providers is maintained here since a provider may span multiple 36 * modules. When a kernel module is unloaded, a provider defined in that module 37 * is unregistered only if no other modules refer to it. The DTrace framework is 38 * responsible for destroying individual probes when a kernel module is 39 * unloaded; in particular, probes may not span multiple kernel modules. 40 */ 41 #include <sys/cdefs.h> 42 __KERNEL_RCSID(0, "$NetBSD: sdt.c,v 1.15 2016/02/06 18:19:59 joerg Exp $"); 43 44 #include <sys/cdefs.h> 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 48 #include <sys/conf.h> 49 #ifdef __FreeBSD__ 50 #include <sys/eventhandler.h> 51 #endif 52 #include <sys/kernel.h> 53 #include <sys/limits.h> 54 #ifdef __FreeBSD__ 55 #include <sys/linker.h> 56 #include <sys/linker_set.h> 57 #endif 58 #include <sys/lock.h> 59 #ifdef __FreeBSD__ 60 #include <sys/lockstat.h> 61 #endif 62 #include <sys/malloc.h> 63 #include <sys/kmem.h> 64 #include <sys/module.h> 65 #include <sys/mutex.h> 66 #include <sys/queue.h> 67 #define KDTRACE_HOOKS 68 #include <sys/sdt.h> 69 70 #include <sys/dtrace.h> 71 #include <sys/dtrace_bsd.h> 72 73 /* DTrace methods. */ 74 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); 75 static void sdt_provide_probes(void *, const dtrace_probedesc_t *); 76 static void sdt_destroy(void *, dtrace_id_t, void *); 77 static int sdt_enable(void *, dtrace_id_t, void *); 78 static void sdt_disable(void *, dtrace_id_t, void *); 79 80 static void sdt_load(void); 81 static int sdt_unload(void); 82 static void sdt_create_provider(struct sdt_provider *); 83 static void sdt_create_probe(struct sdt_probe *); 84 #ifdef __FreeBSD__ 85 static void sdt_kld_load(void *, struct linker_file *); 86 static void sdt_kld_unload_try(void *, struct linker_file *, int *); 87 #endif 88 89 MALLOC_DECLARE(M_SDT); 90 MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); 91 #define SDT_KASSERT(cond, msg) KASSERT(cond) 92 93 static dtrace_pattr_t sdt_attr = { 94 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 95 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, 96 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 97 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 98 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 99 }; 100 101 static dtrace_pops_t sdt_pops = { 102 sdt_provide_probes, 103 NULL, 104 sdt_enable, 105 sdt_disable, 106 NULL, 107 NULL, 108 sdt_getargdesc, 109 NULL, 110 NULL, 111 sdt_destroy, 112 }; 113 114 #ifdef __NetBSD__ 115 static int 116 sdt_open(dev_t dev, int flags, int mode, struct lwp *l) 117 { 118 return (0); 119 } 120 121 static const struct cdevsw sdt_cdevsw = { 122 sdt_open, noclose, noread, nowrite, noioctl, 123 nostop, notty, nopoll, nommap, nokqfilter, nodiscard, 124 D_OTHER 125 }; 126 #endif 127 128 static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 129 130 #ifdef __FreeBSD__ 131 eventhandler_tag sdt_kld_load_tag; 132 eventhandler_tag sdt_kld_unload_try_tag; 133 #endif 134 135 #ifdef __NetBSD__ 136 static char * 137 strdup(const char *s, const struct malloc_type *m) 138 { 139 size_t l = strlen(s) + 1; 140 char *d = malloc(l, m, M_WAITOK); 141 memcpy(d, s, l); 142 return d; 143 } 144 #endif 145 146 static void 147 sdt_create_provider(struct sdt_provider *prov) 148 { 149 struct sdt_provider *curr, *newprov; 150 151 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) 152 if (strcmp(prov->name, curr->name) == 0) { 153 /* The provider has already been defined. */ 154 curr->sdt_refs++; 155 return; 156 } 157 158 /* 159 * Make a copy of prov so that we don't lose fields if its module is 160 * unloaded but the provider isn't destroyed. This could happen with 161 * a provider that spans multiple modules. 162 */ 163 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); 164 newprov->name = strdup(prov->name, M_SDT); 165 prov->sdt_refs = newprov->sdt_refs = 1; 166 167 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); 168 169 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, 170 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); 171 prov->id = newprov->id; 172 } 173 174 static void 175 sdt_create_probe(struct sdt_probe *probe) 176 { 177 struct sdt_provider *prov; 178 char mod[DTRACE_MODNAMELEN]; 179 char func[DTRACE_FUNCNAMELEN]; 180 char name[DTRACE_NAMELEN]; 181 const char *from; 182 char *to; 183 size_t len; 184 185 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) 186 if (strcmp(prov->name, probe->prov->name) == 0) 187 break; 188 189 SDT_KASSERT(prov != NULL, ("probe defined without a provider")); 190 191 #ifdef __FreeBSD__ 192 /* If no module name was specified, use the module filename. */ 193 if (*probe->mod == 0) { 194 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); 195 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) 196 mod[len - 3] = '\0'; 197 } else 198 #endif 199 strlcpy(mod, probe->mod, sizeof(mod)); 200 201 /* 202 * Unfortunately this is necessary because the Solaris DTrace 203 * code mixes consts and non-consts with casts to override 204 * the incompatibilies. On FreeBSD, we use strict warnings 205 * in the C compiler, so we have to respect const vs non-const. 206 */ 207 strlcpy(func, probe->func, sizeof(func)); 208 209 from = probe->name; 210 to = name; 211 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 212 len++, from++, to++) { 213 if (from[0] == '_' && from[1] == '_') { 214 *to = '-'; 215 from++; 216 } else 217 *to = *from; 218 } 219 *to = '\0'; 220 221 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 222 return; 223 224 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 225 } 226 227 /* 228 * Probes are created through the SDT module load/unload hook, so this function 229 * has nothing to do. It only exists because the DTrace provider framework 230 * requires one of provide_probes and provide_module to be defined. 231 */ 232 static void 233 sdt_provide_probes(void *arg, const dtrace_probedesc_t *desc) 234 { 235 } 236 237 static int 238 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 239 { 240 struct sdt_probe *probe = parg; 241 242 #ifdef SDT_DEBUG 243 printf("sdt: %s\n", __func__); 244 #endif 245 246 probe->id = id; 247 #ifdef __FreeBSD__ 248 probe->sdtp_lf->nenabled++; 249 if (strcmp(probe->prov->name, "lockstat") == 0) 250 lockstat_enabled++; 251 #endif 252 return 1; 253 } 254 255 static void 256 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 257 { 258 struct sdt_probe *probe = parg; 259 260 SDT_KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 261 262 #ifdef SDT_DEBUG 263 printf("sdt: %s\n", __func__); 264 #endif 265 266 #ifdef __FreeBSD__ 267 if (strcmp(probe->prov->name, "lockstat") == 0) 268 lockstat_enabled--; 269 probe->sdtp_lf->nenabled--; 270 #endif 271 probe->id = 0; 272 } 273 274 static void 275 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 276 { 277 struct sdt_argtype *argtype; 278 struct sdt_probe *probe = parg; 279 280 #ifdef SDT_DEBUG 281 printf("sdt: %s probe %d\n", __func__, id); 282 printf("%s: probe %d (%s:%s:%s:%s).%d\n", 283 __func__, id, 284 probe->provider, 285 probe->module, 286 probe->function, 287 probe->name, 288 desc->dtargd_ndx); 289 #endif 290 if (desc->dtargd_ndx >= probe->n_args) { 291 desc->dtargd_ndx = DTRACE_ARGNONE; 292 return; 293 } 294 295 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 296 if (desc->dtargd_ndx == argtype->ndx) { 297 desc->dtargd_mapping = desc->dtargd_ndx; 298 if (argtype->type == NULL) { 299 desc->dtargd_native[0] = '\0'; 300 desc->dtargd_xlate[0] = '\0'; 301 continue; 302 } 303 strlcpy(desc->dtargd_native, argtype->type, 304 sizeof(desc->dtargd_native)); 305 if (argtype->xtype != NULL) 306 strlcpy(desc->dtargd_xlate, argtype->xtype, 307 sizeof(desc->dtargd_xlate)); 308 } 309 } 310 } 311 312 static void 313 sdt_destroy(void *arg, dtrace_id_t id, void *parg) 314 { 315 } 316 317 #ifdef __FreeBSD__ 318 /* 319 * Called from the kernel linker when a module is loaded, before 320 * dtrace_module_loaded() is called. This is done so that it's possible to 321 * register new providers when modules are loaded. The DTrace framework 322 * explicitly disallows calling into the framework from the provide_module 323 * provider method, so we cannot do this there. 324 */ 325 static void 326 sdt_kld_load(void *arg __unused, struct linker_file *lf) 327 { 328 struct sdt_provider **prov, **begin, **end; 329 struct sdt_probe **probe, **p_begin, **p_end; 330 struct sdt_argtype **argtype, **a_begin, **a_end; 331 332 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 333 NULL) == 0) { 334 for (prov = begin; prov < end; prov++) 335 sdt_create_provider(*prov); 336 } 337 338 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 339 NULL) == 0) { 340 for (probe = p_begin; probe < p_end; probe++) { 341 (*probe)->sdtp_lf = lf; 342 sdt_create_probe(*probe); 343 TAILQ_INIT(&(*probe)->argtype_list); 344 } 345 } 346 347 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 348 NULL) == 0) { 349 for (argtype = a_begin; argtype < a_end; argtype++) { 350 (*argtype)->probe->n_args++; 351 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 352 *argtype, argtype_entry); 353 } 354 } 355 } 356 357 static void 358 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 359 { 360 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 361 362 if (*error != 0) 363 /* We already have an error, so don't do anything. */ 364 return; 365 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 366 NULL)) 367 /* No DTrace providers are declared in this file. */ 368 return; 369 370 /* 371 * Go through all the providers declared in this linker file and 372 * unregister any that aren't declared in another loaded file. 373 */ 374 for (curr = begin; curr < end; curr++) { 375 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 376 if (strcmp(prov->name, (*curr)->name) != 0) 377 continue; 378 379 if (prov->sdt_refs == 1) { 380 if (dtrace_unregister(prov->id) != 0) { 381 *error = 1; 382 return; 383 } 384 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 385 free(prov->name, M_SDT); 386 free(prov, M_SDT); 387 } else 388 prov->sdt_refs--; 389 break; 390 } 391 } 392 } 393 394 static int 395 sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 396 { 397 398 sdt_kld_load(NULL, lf); 399 400 return (0); 401 } 402 #endif 403 404 #ifdef __NetBSD__ 405 /* 406 * weak symbols don't work in kernel modules; link set end symbols are 407 * weak by default, so we kill that. 408 */ 409 #undef __weak 410 #define __weak 411 __link_set_decl(sdt_providers_set, struct sdt_provider); 412 __link_set_decl(sdt_probes_set, struct sdt_probe); 413 __link_set_decl(sdt_argtypes_set, struct sdt_argtype); 414 415 /* 416 * Unfortunately we don't have linker set functions and event handlers 417 * to support loading and unloading probes in modules... Currently if 418 * modules have probes, if the modules are loaded when sdt is loaded 419 * they will work, but they will crash unloading. 420 */ 421 static void 422 sdt_link_set_load(void) 423 { 424 struct sdt_provider * const *provider; 425 struct sdt_probe * const *probe; 426 struct sdt_argtype * const *argtype; 427 428 __link_set_foreach(provider, sdt_providers_set) { 429 sdt_create_provider(*provider); 430 } 431 432 __link_set_foreach(probe, sdt_probes_set) { 433 (*probe)->sdtp_lf = NULL; // XXX: we don't support it 434 sdt_create_probe(*probe); 435 TAILQ_INIT(&(*probe)->argtype_list); 436 } 437 438 __link_set_foreach(argtype, sdt_argtypes_set) { 439 (*argtype)->probe->n_args++; 440 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 441 *argtype, argtype_entry); 442 } 443 } 444 445 static void 446 sdt_link_set_unload(void) 447 { 448 struct sdt_provider * const *curr, *prov, *tmp; 449 450 /* 451 * Go through all the providers declared in this linker file and 452 * unregister any that aren't declared in another loaded file. 453 */ 454 __link_set_foreach(curr, sdt_providers_set) { 455 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 456 if (strcmp(prov->name, (*curr)->name) != 0) 457 continue; 458 459 if (prov->sdt_refs == 1) { 460 if (dtrace_unregister(prov->id) != 0) { 461 return; 462 } 463 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 464 free(__UNCONST(prov->name), M_SDT); 465 free(prov, M_SDT); 466 } else 467 prov->sdt_refs--; 468 break; 469 } 470 } 471 } 472 #endif 473 474 475 static void 476 sdt_load(void) 477 { 478 TAILQ_INIT(&sdt_prov_list); 479 480 sdt_init(dtrace_probe); 481 #ifdef __FreeBSD__ 482 /* Pick up probes from the kernel and already-loaded linker files. */ 483 linker_file_foreach(sdt_linker_file_cb, NULL); 484 #endif 485 #ifdef __NetBSD__ 486 sdt_link_set_load(); 487 #endif 488 } 489 490 static int 491 sdt_unload(void) 492 { 493 struct sdt_provider *prov, *tmp; 494 int ret; 495 496 sdt_exit(); 497 498 #ifdef __NetBSD__ 499 sdt_link_set_unload(); 500 #endif 501 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 502 ret = dtrace_unregister(prov->id); 503 if (ret != 0) 504 return ret; 505 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 506 free(__UNCONST(prov->name), M_SDT); 507 free(prov, M_SDT); 508 } 509 510 return 0; 511 } 512 513 #ifdef __FreeBSD__ 514 static int 515 sdt_modevent(module_t mod __unused, int type, void *data __unused) 516 { 517 int error = 0; 518 519 switch (type) { 520 case MOD_LOAD: 521 sdt_load(); 522 break; 523 524 case MOD_UNLOAD: 525 error = sdt_unload(); 526 break; 527 528 case MOD_SHUTDOWN: 529 break; 530 531 default: 532 error = EOPNOTSUPP; 533 break; 534 } 535 536 return (error); 537 } 538 539 DEV_MODULE(sdt, sdt_modevent, NULL); 540 MODULE_VERSION(sdt, 1); 541 MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 542 MODULE_DEPEND(sdt, opensolaris, 1, 1, 1); 543 #endif 544 545 #ifdef __NetBSD__ 546 static int 547 dtrace_sdt_modcmd(modcmd_t cmd, void *data) 548 { 549 int bmajor = -1, cmajor = -1; 550 int error; 551 552 switch (cmd) { 553 case MODULE_CMD_INIT: 554 sdt_load(); 555 return devsw_attach("sdt", NULL, &bmajor, 556 &sdt_cdevsw, &cmajor); 557 case MODULE_CMD_FINI: 558 error = sdt_unload(); 559 if (error != 0) 560 return error; 561 return devsw_detach(NULL, &sdt_cdevsw); 562 case MODULE_CMD_AUTOUNLOAD: 563 return EBUSY; 564 default: 565 error = EOPNOTSUPP; 566 break; 567 } 568 return error; 569 } 570 571 MODULE(MODULE_CLASS_MISC, dtrace_sdt, "dtrace"); 572 #endif 573