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 297771 2016-04-10 01:24:27Z 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 1.20 2019/03/09 18:53:52 kamil Exp $"); 43 44 #include <sys/cdefs.h> 45 #include <sys/proc.h> 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 49 #include <sys/conf.h> 50 #ifdef __FreeBSD__ 51 #include <sys/eventhandler.h> 52 #endif 53 #include <sys/kernel.h> 54 #include <sys/syslimits.h> 55 #ifdef __FreeBSD__ 56 #include <sys/linker.h> 57 #include <sys/linker_set.h> 58 #endif 59 #include <sys/lock.h> 60 #ifdef __FreeBSD__ 61 #include <sys/lockstat.h> 62 #endif 63 #include <sys/malloc.h> 64 #include <sys/kmem.h> 65 #include <sys/module.h> 66 #include <sys/mutex.h> 67 #include <sys/queue.h> 68 #define KDTRACE_HOOKS 69 #include <sys/sdt.h> 70 71 #include <sys/dtrace.h> 72 #include <sys/dtrace_bsd.h> 73 74 /* DTrace methods. */ 75 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); 76 static void sdt_provide_probes(void *, dtrace_probedesc_t *); 77 static void sdt_destroy(void *, dtrace_id_t, void *); 78 static int sdt_enable(void *, dtrace_id_t, void *); 79 static void sdt_disable(void *, dtrace_id_t, void *); 80 81 static void sdt_load(void); 82 static int sdt_unload(void); 83 static void sdt_create_provider(struct sdt_provider *); 84 static void sdt_create_probe(struct sdt_probe *); 85 #ifdef __FreeBSD__ 86 static void sdt_kld_load(void *, struct linker_file *); 87 static void sdt_kld_unload_try(void *, struct linker_file *, int *); 88 #endif 89 90 MALLOC_DECLARE(M_SDT); 91 MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); 92 #define SDT_KASSERT(cond, msg) KASSERT(cond) 93 94 static dtrace_pattr_t sdt_attr = { 95 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 96 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, 97 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 98 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 99 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 100 }; 101 102 static dtrace_pops_t sdt_pops = { 103 sdt_provide_probes, 104 NULL, 105 sdt_enable, 106 sdt_disable, 107 NULL, 108 NULL, 109 sdt_getargdesc, 110 NULL, 111 NULL, 112 sdt_destroy, 113 }; 114 115 #ifdef __NetBSD__ 116 static int 117 sdt_open(dev_t dev, int flags, int mode, struct lwp *l) 118 { 119 return 0; 120 } 121 122 static const struct cdevsw sdt_cdevsw = { 123 .d_open = sdt_open, 124 .d_close = noclose, 125 .d_read = noread, 126 .d_write = nowrite, 127 .d_ioctl = noioctl, 128 .d_stop = nostop, 129 .d_tty = notty, 130 .d_poll = nopoll, 131 .d_mmap = nommap, 132 .d_kqfilter = nokqfilter, 133 .d_discard = nodiscard, 134 .d_flag = D_OTHER 135 }; 136 #endif 137 138 static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 139 140 #ifdef __FreeBSD__ 141 static eventhandler_tag sdt_kld_load_tag; 142 static eventhandler_tag sdt_kld_unload_try_tag; 143 #endif 144 145 #ifdef __NetBSD__ 146 static char * 147 strdup(const char *s, const struct malloc_type *m) 148 { 149 size_t l = strlen(s) + 1; 150 char *d = malloc(l, m, M_WAITOK); 151 memcpy(d, s, l); 152 return d; 153 } 154 #endif 155 156 static void 157 sdt_create_provider(struct sdt_provider *prov) 158 { 159 struct sdt_provider *curr, *newprov; 160 161 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) 162 if (strcmp(prov->name, curr->name) == 0) { 163 /* The provider has already been defined. */ 164 curr->sdt_refs++; 165 return; 166 } 167 168 /* 169 * Make a copy of prov so that we don't lose fields if its module is 170 * unloaded but the provider isn't destroyed. This could happen with 171 * a provider that spans multiple modules. 172 */ 173 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); 174 newprov->name = strdup(prov->name, M_SDT); 175 prov->sdt_refs = newprov->sdt_refs = 1; 176 177 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); 178 179 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, 180 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); 181 prov->id = newprov->id; 182 } 183 184 static void 185 sdt_create_probe(struct sdt_probe *probe) 186 { 187 struct sdt_provider *prov; 188 char mod[DTRACE_MODNAMELEN]; 189 char func[DTRACE_FUNCNAMELEN]; 190 char name[DTRACE_NAMELEN]; 191 const char *from; 192 char *to; 193 size_t len; 194 195 if (probe->version != (int)sizeof(*probe)) { 196 printf("ignoring probe %p, version %u expected %u\n", 197 probe, probe->version, (int)sizeof(*probe)); 198 return; 199 } 200 201 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) 202 if (strcmp(prov->name, probe->prov->name) == 0) 203 break; 204 205 SDT_KASSERT(prov != NULL, ("probe defined without a provider")); 206 207 #ifdef __FreeBSD__ 208 /* If no module name was specified, use the module filename. */ 209 if (*probe->mod == 0) { 210 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); 211 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) 212 mod[len - 3] = '\0'; 213 } else 214 #endif 215 strlcpy(mod, probe->mod, sizeof(mod)); 216 217 /* 218 * Unfortunately this is necessary because the Solaris DTrace 219 * code mixes consts and non-consts with casts to override 220 * the incompatibilies. On FreeBSD, we use strict warnings 221 * in the C compiler, so we have to respect const vs non-const. 222 */ 223 strlcpy(func, probe->func, sizeof(func)); 224 if (func[0] == '\0') 225 strcpy(func, "none"); 226 227 from = probe->name; 228 to = name; 229 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 230 len++, from++, to++) { 231 if (from[0] == '_' && from[1] == '_') { 232 *to = '-'; 233 from++; 234 } else 235 *to = *from; 236 } 237 *to = '\0'; 238 239 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 240 return; 241 242 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 243 } 244 245 /* 246 * Probes are created through the SDT module load/unload hook, so this function 247 * has nothing to do. It only exists because the DTrace provider framework 248 * requires one of provide_probes and provide_module to be defined. 249 */ 250 static void 251 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 252 { 253 } 254 255 static int 256 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 257 { 258 struct sdt_probe *probe = parg; 259 260 probe->id = id; 261 #ifdef __FreeBSD__ 262 probe->sdtp_lf->nenabled++; 263 if (strcmp(probe->prov->name, "lockstat") == 0) 264 lockstat_enabled++; 265 #endif 266 return 1; 267 } 268 269 static void 270 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 271 { 272 struct sdt_probe *probe = parg; 273 274 #ifdef __FreeBSD__ 275 SDT_KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 276 if (strcmp(probe->prov->name, "lockstat") == 0) 277 lockstat_enabled--; 278 probe->sdtp_lf->nenabled--; 279 #endif 280 probe->id = 0; 281 } 282 283 static void 284 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 285 { 286 struct sdt_argtype *argtype; 287 struct sdt_probe *probe = parg; 288 289 if (desc->dtargd_ndx >= probe->n_args) { 290 desc->dtargd_ndx = DTRACE_ARGNONE; 291 return; 292 } 293 294 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 295 if (desc->dtargd_ndx == argtype->ndx) { 296 desc->dtargd_mapping = desc->dtargd_ndx; 297 if (argtype->type == NULL) { 298 desc->dtargd_native[0] = '\0'; 299 desc->dtargd_xlate[0] = '\0'; 300 continue; 301 } 302 strlcpy(desc->dtargd_native, argtype->type, 303 sizeof(desc->dtargd_native)); 304 if (argtype->xtype != NULL) 305 strlcpy(desc->dtargd_xlate, argtype->xtype, 306 sizeof(desc->dtargd_xlate)); 307 } 308 } 309 } 310 311 static void 312 sdt_destroy(void *arg, dtrace_id_t id, void *parg) 313 { 314 } 315 316 #ifdef __FreeBSD__ 317 /* 318 * Called from the kernel linker when a module is loaded, before 319 * dtrace_module_loaded() is called. This is done so that it's possible to 320 * register new providers when modules are loaded. The DTrace framework 321 * explicitly disallows calling into the framework from the provide_module 322 * provider method, so we cannot do this there. 323 */ 324 static void 325 sdt_kld_load(void *arg __unused, struct linker_file *lf) 326 { 327 struct sdt_provider **prov, **begin, **end; 328 struct sdt_probe **probe, **p_begin, **p_end; 329 struct sdt_argtype **argtype, **a_begin, **a_end; 330 331 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 332 NULL) == 0) { 333 for (prov = begin; prov < end; prov++) 334 sdt_create_provider(*prov); 335 } 336 337 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 338 NULL) == 0) { 339 for (probe = p_begin; probe < p_end; probe++) { 340 (*probe)->sdtp_lf = lf; 341 sdt_create_probe(*probe); 342 TAILQ_INIT(&(*probe)->argtype_list); 343 } 344 } 345 346 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 347 NULL) == 0) { 348 for (argtype = a_begin; argtype < a_end; argtype++) { 349 (*argtype)->probe->n_args++; 350 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 351 *argtype, argtype_entry); 352 } 353 } 354 } 355 356 static void 357 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 358 { 359 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 360 361 if (*error != 0) 362 /* We already have an error, so don't do anything. */ 363 return; 364 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 365 NULL)) 366 /* No DTrace providers are declared in this file. */ 367 return; 368 369 /* 370 * Go through all the providers declared in this linker file and 371 * unregister any that aren't declared in another loaded file. 372 */ 373 for (curr = begin; curr < end; curr++) { 374 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 375 if (strcmp(prov->name, (*curr)->name) != 0) 376 continue; 377 378 if (prov->sdt_refs == 1) { 379 if (dtrace_unregister(prov->id) != 0) { 380 *error = 1; 381 return; 382 } 383 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 384 free(prov->name, M_SDT); 385 free(prov, M_SDT); 386 } else 387 prov->sdt_refs--; 388 break; 389 } 390 } 391 } 392 393 static int 394 sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 395 { 396 397 sdt_kld_load(NULL, lf); 398 399 return (0); 400 } 401 #endif 402 403 #ifdef __NetBSD__ 404 /* 405 * weak symbols don't work in kernel modules; link set end symbols are 406 * weak by default, so we kill that. 407 */ 408 #undef __weak 409 #define __weak 410 __link_set_decl(sdt_providers_set, struct sdt_provider); 411 __link_set_decl(sdt_probes_set, struct sdt_probe); 412 __link_set_decl(sdt_argtypes_set, struct sdt_argtype); 413 414 /* 415 * Unfortunately we don't have linker set functions and event handlers 416 * to support loading and unloading probes in modules... Currently if 417 * modules have probes, if the modules are loaded when sdt is loaded 418 * they will work, but they will crash unloading. 419 */ 420 static void 421 sdt_link_set_load(void) 422 { 423 struct sdt_provider * const *provider; 424 struct sdt_probe * const *probe; 425 struct sdt_argtype * const *argtype; 426 427 __link_set_foreach(provider, sdt_providers_set) { 428 sdt_create_provider(*provider); 429 } 430 431 __link_set_foreach(probe, sdt_probes_set) { 432 (*probe)->sdtp_lf = NULL; // XXX: we don't support it 433 sdt_create_probe(*probe); 434 TAILQ_INIT(&(*probe)->argtype_list); 435 } 436 437 __link_set_foreach(argtype, sdt_argtypes_set) { 438 (*argtype)->probe->n_args++; 439 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 440 *argtype, argtype_entry); 441 } 442 } 443 444 static void 445 sdt_link_set_unload(void) 446 { 447 struct sdt_provider * const *curr, *prov, *tmp; 448 449 /* 450 * Go through all the providers declared in this linker file and 451 * unregister any that aren't declared in another loaded file. 452 */ 453 __link_set_foreach(curr, sdt_providers_set) { 454 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 455 if (strcmp(prov->name, (*curr)->name) != 0) 456 continue; 457 458 if (prov->sdt_refs == 1) { 459 if (dtrace_unregister(prov->id) != 0) { 460 return; 461 } 462 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 463 free(__UNCONST(prov->name), M_SDT); 464 free(prov, M_SDT); 465 } else 466 prov->sdt_refs--; 467 break; 468 } 469 } 470 } 471 #endif 472 473 474 static void 475 sdt_load(void) 476 { 477 TAILQ_INIT(&sdt_prov_list); 478 479 #ifdef __FreeBSD__ 480 sdt_probe_func = dtrace_probe; 481 482 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 483 EVENTHANDLER_PRI_ANY); 484 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 485 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 486 487 /* Pick up probes from the kernel and already-loaded linker files. */ 488 linker_file_foreach(sdt_linker_file_cb, NULL); 489 #endif 490 #ifdef __NetBSD__ 491 sdt_init(dtrace_probe); 492 sdt_link_set_load(); 493 #endif 494 } 495 496 static int 497 sdt_unload(void) 498 { 499 struct sdt_provider *prov, *tmp; 500 int ret; 501 502 #ifdef __FreeBSD__ 503 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 504 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 505 506 sdt_probe_func = sdt_probe_stub; 507 #endif 508 509 #ifdef __NetBSD__ 510 sdt_exit(); 511 512 sdt_link_set_unload(); 513 #endif 514 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 515 ret = dtrace_unregister(prov->id); 516 if (ret != 0) 517 return (ret); 518 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 519 free(__UNCONST(prov->name), M_SDT); 520 free(prov, M_SDT); 521 } 522 523 return (0); 524 } 525 526 #ifdef __FreeBSD__ 527 static int 528 sdt_modevent(module_t mod __unused, int type, void *data __unused) 529 { 530 531 switch (type) { 532 case MOD_LOAD: 533 case MOD_UNLOAD: 534 case MOD_SHUTDOWN: 535 return (0); 536 default: 537 return (EOPNOTSUPP); 538 } 539 } 540 541 SYSINIT(sdt_load, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_load, NULL); 542 SYSUNINIT(sdt_unload, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_unload, NULL); 543 544 DEV_MODULE(sdt, sdt_modevent, NULL); 545 MODULE_VERSION(sdt, 1); 546 MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 547 #endif 548 549 #ifdef __NetBSD__ 550 static int 551 dtrace_sdt_modcmd(modcmd_t cmd, void *data) 552 { 553 int bmajor = -1, cmajor = 353; 554 int error; 555 556 switch (cmd) { 557 case MODULE_CMD_INIT: 558 sdt_load(); 559 return devsw_attach("sdt", NULL, &bmajor, 560 &sdt_cdevsw, &cmajor); 561 case MODULE_CMD_FINI: 562 error = sdt_unload(); 563 if (error != 0) 564 return error; 565 return devsw_detach(NULL, &sdt_cdevsw); 566 case MODULE_CMD_AUTOUNLOAD: 567 return EBUSY; 568 default: 569 error = EOPNOTSUPP; 570 break; 571 } 572 return error; 573 } 574 575 MODULE(MODULE_CLASS_MISC, dtrace_sdt, "dtrace"); 576 #endif 577