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