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 dtrace_pattr_t sdt_attr = { 80 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 81 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, 82 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 83 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 84 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 85 }; 86 87 static dtrace_pops_t sdt_pops = { 88 sdt_provide_probes, 89 NULL, 90 sdt_enable, 91 sdt_disable, 92 NULL, 93 NULL, 94 sdt_getargdesc, 95 NULL, 96 NULL, 97 sdt_destroy, 98 }; 99 100 static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 101 102 eventhandler_tag sdt_kld_load_tag; 103 eventhandler_tag sdt_kld_unload_try_tag; 104 105 static void 106 sdt_create_provider(struct sdt_provider *prov) 107 { 108 struct sdt_provider *curr, *newprov; 109 110 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) 111 if (strcmp(prov->name, curr->name) == 0) { 112 /* The provider has already been defined. */ 113 curr->sdt_refs++; 114 return; 115 } 116 117 /* 118 * Make a copy of prov so that we don't lose fields if its module is 119 * unloaded but the provider isn't destroyed. This could happen with 120 * a provider that spans multiple modules. 121 */ 122 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); 123 newprov->name = strdup(prov->name, M_SDT); 124 prov->sdt_refs = newprov->sdt_refs = 1; 125 126 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); 127 128 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, 129 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); 130 prov->id = newprov->id; 131 } 132 133 static void 134 sdt_create_probe(struct sdt_probe *probe) 135 { 136 struct sdt_provider *prov; 137 char mod[DTRACE_MODNAMELEN]; 138 char func[DTRACE_FUNCNAMELEN]; 139 char name[DTRACE_NAMELEN]; 140 const char *from; 141 char *to; 142 size_t len; 143 144 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) 145 if (strcmp(prov->name, probe->prov->name) == 0) 146 break; 147 148 KASSERT(prov != NULL, ("probe defined without a provider")); 149 150 /* If no module name was specified, use the module filename. */ 151 if (*probe->mod == 0) { 152 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); 153 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) 154 mod[len - 3] = '\0'; 155 } else 156 strlcpy(mod, probe->mod, sizeof(mod)); 157 158 /* 159 * Unfortunately this is necessary because the Solaris DTrace 160 * code mixes consts and non-consts with casts to override 161 * the incompatibilies. On FreeBSD, we use strict warnings 162 * in the C compiler, so we have to respect const vs non-const. 163 */ 164 strlcpy(func, probe->func, sizeof(func)); 165 166 from = probe->name; 167 to = name; 168 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 169 len++, from++, to++) { 170 if (from[0] == '_' && from[1] == '_') { 171 *to = '-'; 172 from++; 173 } else 174 *to = *from; 175 } 176 *to = '\0'; 177 178 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 179 return; 180 181 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 182 } 183 184 /* 185 * Probes are created through the SDT module load/unload hook, so this function 186 * has nothing to do. It only exists because the DTrace provider framework 187 * requires one of provide_probes and provide_module to be defined. 188 */ 189 static void 190 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 191 { 192 } 193 194 static void 195 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 196 { 197 struct sdt_probe *probe = parg; 198 199 probe->id = id; 200 probe->sdtp_lf->nenabled++; 201 if (strcmp(probe->prov->name, "lockstat") == 0) 202 lockstat_enabled++; 203 } 204 205 static void 206 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 207 { 208 struct sdt_probe *probe = parg; 209 210 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 211 212 if (strcmp(probe->prov->name, "lockstat") == 0) 213 lockstat_enabled--; 214 probe->id = 0; 215 probe->sdtp_lf->nenabled--; 216 } 217 218 static void 219 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 220 { 221 struct sdt_argtype *argtype; 222 struct sdt_probe *probe = parg; 223 224 if (desc->dtargd_ndx >= probe->n_args) { 225 desc->dtargd_ndx = DTRACE_ARGNONE; 226 return; 227 } 228 229 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 230 if (desc->dtargd_ndx == argtype->ndx) { 231 desc->dtargd_mapping = desc->dtargd_ndx; 232 if (argtype->type == NULL) { 233 desc->dtargd_native[0] = '\0'; 234 desc->dtargd_xlate[0] = '\0'; 235 continue; 236 } 237 strlcpy(desc->dtargd_native, argtype->type, 238 sizeof(desc->dtargd_native)); 239 if (argtype->xtype != NULL) 240 strlcpy(desc->dtargd_xlate, argtype->xtype, 241 sizeof(desc->dtargd_xlate)); 242 } 243 } 244 } 245 246 static void 247 sdt_destroy(void *arg, dtrace_id_t id, void *parg) 248 { 249 } 250 251 /* 252 * Called from the kernel linker when a module is loaded, before 253 * dtrace_module_loaded() is called. This is done so that it's possible to 254 * register new providers when modules are loaded. The DTrace framework 255 * explicitly disallows calling into the framework from the provide_module 256 * provider method, so we cannot do this there. 257 */ 258 static void 259 sdt_kld_load(void *arg __unused, struct linker_file *lf) 260 { 261 struct sdt_provider **prov, **begin, **end; 262 struct sdt_probe **probe, **p_begin, **p_end; 263 struct sdt_argtype **argtype, **a_begin, **a_end; 264 265 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 266 NULL) == 0) { 267 for (prov = begin; prov < end; prov++) 268 sdt_create_provider(*prov); 269 } 270 271 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 272 NULL) == 0) { 273 for (probe = p_begin; probe < p_end; probe++) { 274 (*probe)->sdtp_lf = lf; 275 sdt_create_probe(*probe); 276 TAILQ_INIT(&(*probe)->argtype_list); 277 } 278 } 279 280 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 281 NULL) == 0) { 282 for (argtype = a_begin; argtype < a_end; argtype++) { 283 (*argtype)->probe->n_args++; 284 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 285 *argtype, argtype_entry); 286 } 287 } 288 } 289 290 static void 291 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 292 { 293 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 294 295 if (*error != 0) 296 /* We already have an error, so don't do anything. */ 297 return; 298 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 299 NULL)) 300 /* No DTrace providers are declared in this file. */ 301 return; 302 303 /* 304 * Go through all the providers declared in this linker file and 305 * unregister any that aren't declared in another loaded file. 306 */ 307 for (curr = begin; curr < end; curr++) { 308 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 309 if (strcmp(prov->name, (*curr)->name) != 0) 310 continue; 311 312 if (prov->sdt_refs == 1) { 313 if (dtrace_unregister(prov->id) != 0) { 314 *error = 1; 315 return; 316 } 317 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 318 free(prov->name, M_SDT); 319 free(prov, M_SDT); 320 } else 321 prov->sdt_refs--; 322 break; 323 } 324 } 325 } 326 327 static int 328 sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 329 { 330 331 sdt_kld_load(NULL, lf); 332 333 return (0); 334 } 335 336 static void 337 sdt_load() 338 { 339 340 TAILQ_INIT(&sdt_prov_list); 341 342 sdt_probe_func = dtrace_probe; 343 344 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 345 EVENTHANDLER_PRI_ANY); 346 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 347 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 348 349 /* Pick up probes from the kernel and already-loaded linker files. */ 350 linker_file_foreach(sdt_linker_file_cb, NULL); 351 } 352 353 static int 354 sdt_unload() 355 { 356 struct sdt_provider *prov, *tmp; 357 int ret; 358 359 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 360 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 361 362 sdt_probe_func = sdt_probe_stub; 363 364 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 365 ret = dtrace_unregister(prov->id); 366 if (ret != 0) 367 return (ret); 368 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 369 free(prov->name, M_SDT); 370 free(prov, M_SDT); 371 } 372 373 return (0); 374 } 375 376 static int 377 sdt_modevent(module_t mod __unused, int type, void *data __unused) 378 { 379 int error = 0; 380 381 switch (type) { 382 case MOD_LOAD: 383 sdt_load(); 384 break; 385 386 case MOD_UNLOAD: 387 error = sdt_unload(); 388 break; 389 390 case MOD_SHUTDOWN: 391 break; 392 393 default: 394 error = EOPNOTSUPP; 395 break; 396 } 397 398 return (error); 399 } 400 401 DEV_MODULE(sdt, sdt_modevent, NULL); 402 MODULE_VERSION(sdt, 1); 403 MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 404 MODULE_DEPEND(sdt, opensolaris, 1, 1, 1); 405