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 * $FreeBSD$ 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 42 #include <sys/cdefs.h> 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 46 #include <sys/conf.h> 47 #include <sys/eventhandler.h> 48 #include <sys/kernel.h> 49 #include <sys/limits.h> 50 #include <sys/linker.h> 51 #include <sys/linker_set.h> 52 #include <sys/lock.h> 53 #include <sys/lockstat.h> 54 #include <sys/malloc.h> 55 #include <sys/module.h> 56 #include <sys/mutex.h> 57 #include <sys/queue.h> 58 #include <sys/sdt.h> 59 60 #include <sys/dtrace.h> 61 #include <sys/dtrace_bsd.h> 62 63 /* DTrace methods. */ 64 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); 65 static void sdt_provide_probes(void *, dtrace_probedesc_t *); 66 static void sdt_destroy(void *, dtrace_id_t, void *); 67 static void sdt_enable(void *, dtrace_id_t, void *); 68 static void sdt_disable(void *, dtrace_id_t, void *); 69 70 static void sdt_load(void); 71 static int sdt_unload(void); 72 static void sdt_create_provider(struct sdt_provider *); 73 static void sdt_create_probe(struct sdt_probe *); 74 static void sdt_kld_load(void *, struct linker_file *); 75 static void sdt_kld_unload_try(void *, struct linker_file *, int *); 76 77 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); 78 79 static int sdt_probes_enabled_count; 80 static int lockstat_enabled_count; 81 82 static dtrace_pattr_t sdt_attr = { 83 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 84 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, 85 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 86 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 87 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 88 }; 89 90 static dtrace_pops_t sdt_pops = { 91 .dtps_provide = sdt_provide_probes, 92 .dtps_provide_module = NULL, 93 .dtps_enable = sdt_enable, 94 .dtps_disable = sdt_disable, 95 .dtps_suspend = NULL, 96 .dtps_resume = NULL, 97 .dtps_getargdesc = sdt_getargdesc, 98 .dtps_getargval = NULL, 99 .dtps_usermode = NULL, 100 .dtps_destroy = sdt_destroy, 101 }; 102 103 static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 104 105 static eventhandler_tag sdt_kld_load_tag; 106 static eventhandler_tag sdt_kld_unload_try_tag; 107 108 static void 109 sdt_create_provider(struct sdt_provider *prov) 110 { 111 struct sdt_provider *curr, *newprov; 112 113 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) 114 if (strcmp(prov->name, curr->name) == 0) { 115 /* The provider has already been defined. */ 116 curr->sdt_refs++; 117 return; 118 } 119 120 /* 121 * Make a copy of prov so that we don't lose fields if its module is 122 * unloaded but the provider isn't destroyed. This could happen with 123 * a provider that spans multiple modules. 124 */ 125 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); 126 newprov->name = strdup(prov->name, M_SDT); 127 prov->sdt_refs = newprov->sdt_refs = 1; 128 129 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); 130 131 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, 132 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); 133 prov->id = newprov->id; 134 } 135 136 static void 137 sdt_create_probe(struct sdt_probe *probe) 138 { 139 struct sdt_provider *prov; 140 char mod[DTRACE_MODNAMELEN]; 141 char func[DTRACE_FUNCNAMELEN]; 142 char name[DTRACE_NAMELEN]; 143 const char *from; 144 char *to; 145 size_t len; 146 147 if (probe->version != (int)sizeof(*probe)) { 148 printf("ignoring probe %p, version %u expected %u\n", 149 probe, probe->version, (int)sizeof(*probe)); 150 return; 151 } 152 153 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) 154 if (strcmp(prov->name, probe->prov->name) == 0) 155 break; 156 157 KASSERT(prov != NULL, ("probe defined without a provider")); 158 159 /* If no module name was specified, use the module filename. */ 160 if (*probe->mod == 0) { 161 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); 162 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) 163 mod[len - 3] = '\0'; 164 } else 165 strlcpy(mod, probe->mod, sizeof(mod)); 166 167 /* 168 * Unfortunately this is necessary because the Solaris DTrace 169 * code mixes consts and non-consts with casts to override 170 * the incompatibilies. On FreeBSD, we use strict warnings 171 * in the C compiler, so we have to respect const vs non-const. 172 */ 173 strlcpy(func, probe->func, sizeof(func)); 174 if (func[0] == '\0') 175 strcpy(func, "none"); 176 177 from = probe->name; 178 to = name; 179 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 180 len++, from++, to++) { 181 if (from[0] == '_' && from[1] == '_') { 182 *to = '-'; 183 from++; 184 } else 185 *to = *from; 186 } 187 *to = '\0'; 188 189 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 190 return; 191 192 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 193 } 194 195 /* 196 * Probes are created through the SDT module load/unload hook, so this function 197 * has nothing to do. It only exists because the DTrace provider framework 198 * requires one of provide_probes and provide_module to be defined. 199 */ 200 static void 201 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 202 { 203 } 204 205 static void 206 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 207 { 208 struct sdt_probe *probe = parg; 209 210 probe->id = id; 211 probe->sdtp_lf->nenabled++; 212 if (strcmp(probe->prov->name, "lockstat") == 0) { 213 lockstat_enabled_count++; 214 if (lockstat_enabled_count == 1) 215 lockstat_enabled = true; 216 } 217 sdt_probes_enabled_count++; 218 if (sdt_probes_enabled_count == 1) 219 sdt_probes_enabled = true; 220 } 221 222 static void 223 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 224 { 225 struct sdt_probe *probe = parg; 226 227 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 228 229 sdt_probes_enabled_count--; 230 if (sdt_probes_enabled_count == 0) 231 sdt_probes_enabled = false; 232 if (strcmp(probe->prov->name, "lockstat") == 0) { 233 lockstat_enabled_count--; 234 if (lockstat_enabled_count == 0) 235 lockstat_enabled = false; 236 } 237 probe->id = 0; 238 probe->sdtp_lf->nenabled--; 239 } 240 241 static void 242 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 243 { 244 struct sdt_argtype *argtype; 245 struct sdt_probe *probe = parg; 246 247 if (desc->dtargd_ndx >= probe->n_args) { 248 desc->dtargd_ndx = DTRACE_ARGNONE; 249 return; 250 } 251 252 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 253 if (desc->dtargd_ndx == argtype->ndx) { 254 desc->dtargd_mapping = desc->dtargd_ndx; 255 if (argtype->type == NULL) { 256 desc->dtargd_native[0] = '\0'; 257 desc->dtargd_xlate[0] = '\0'; 258 continue; 259 } 260 strlcpy(desc->dtargd_native, argtype->type, 261 sizeof(desc->dtargd_native)); 262 if (argtype->xtype != NULL) 263 strlcpy(desc->dtargd_xlate, argtype->xtype, 264 sizeof(desc->dtargd_xlate)); 265 } 266 } 267 } 268 269 static void 270 sdt_destroy(void *arg, dtrace_id_t id, void *parg) 271 { 272 } 273 274 /* 275 * Called from the kernel linker when a module is loaded, before 276 * dtrace_module_loaded() is called. This is done so that it's possible to 277 * register new providers when modules are loaded. The DTrace framework 278 * explicitly disallows calling into the framework from the provide_module 279 * provider method, so we cannot do this there. 280 */ 281 static void 282 sdt_kld_load(void *arg __unused, struct linker_file *lf) 283 { 284 struct sdt_provider **prov, **begin, **end; 285 struct sdt_probe **probe, **p_begin, **p_end; 286 struct sdt_argtype **argtype, **a_begin, **a_end; 287 288 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 289 NULL) == 0) { 290 for (prov = begin; prov < end; prov++) 291 sdt_create_provider(*prov); 292 } 293 294 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 295 NULL) == 0) { 296 for (probe = p_begin; probe < p_end; probe++) { 297 (*probe)->sdtp_lf = lf; 298 sdt_create_probe(*probe); 299 TAILQ_INIT(&(*probe)->argtype_list); 300 } 301 } 302 303 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 304 NULL) == 0) { 305 for (argtype = a_begin; argtype < a_end; argtype++) { 306 (*argtype)->probe->n_args++; 307 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 308 *argtype, argtype_entry); 309 } 310 } 311 } 312 313 static void 314 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 315 { 316 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 317 318 if (*error != 0) 319 /* We already have an error, so don't do anything. */ 320 return; 321 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 322 NULL)) 323 /* No DTrace providers are declared in this file. */ 324 return; 325 326 /* 327 * Go through all the providers declared in this linker file and 328 * unregister any that aren't declared in another loaded file. 329 */ 330 for (curr = begin; curr < end; curr++) { 331 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 332 if (strcmp(prov->name, (*curr)->name) != 0) 333 continue; 334 335 if (prov->sdt_refs == 1) { 336 if (dtrace_unregister(prov->id) != 0) { 337 *error = 1; 338 return; 339 } 340 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 341 free(prov->name, M_SDT); 342 free(prov, M_SDT); 343 } else 344 prov->sdt_refs--; 345 break; 346 } 347 } 348 } 349 350 static int 351 sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 352 { 353 354 sdt_kld_load(NULL, lf); 355 356 return (0); 357 } 358 359 static void 360 sdt_load() 361 { 362 363 TAILQ_INIT(&sdt_prov_list); 364 365 sdt_probe_func = dtrace_probe; 366 367 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 368 EVENTHANDLER_PRI_ANY); 369 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 370 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 371 372 /* Pick up probes from the kernel and already-loaded linker files. */ 373 linker_file_foreach(sdt_linker_file_cb, NULL); 374 } 375 376 static int 377 sdt_unload() 378 { 379 struct sdt_provider *prov, *tmp; 380 int ret; 381 382 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 383 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 384 385 sdt_probe_func = sdt_probe_stub; 386 387 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 388 ret = dtrace_unregister(prov->id); 389 if (ret != 0) 390 return (ret); 391 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 392 free(prov->name, M_SDT); 393 free(prov, M_SDT); 394 } 395 396 return (0); 397 } 398 399 static int 400 sdt_modevent(module_t mod __unused, int type, void *data __unused) 401 { 402 403 switch (type) { 404 case MOD_LOAD: 405 case MOD_UNLOAD: 406 case MOD_SHUTDOWN: 407 return (0); 408 default: 409 return (EOPNOTSUPP); 410 } 411 } 412 413 SYSINIT(sdt_load, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_load, NULL); 414 SYSUNINIT(sdt_unload, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_unload, NULL); 415 416 DEV_MODULE(sdt, sdt_modevent, NULL); 417 MODULE_VERSION(sdt, 1); 418 MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 419