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/malloc.h> 54 #include <sys/module.h> 55 #include <sys/mutex.h> 56 #include <sys/queue.h> 57 #include <sys/sdt.h> 58 59 #include <sys/dtrace.h> 60 #include <sys/dtrace_bsd.h> 61 62 /* DTrace methods. */ 63 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); 64 static void sdt_provide_probes(void *, dtrace_probedesc_t *); 65 static void sdt_destroy(void *, dtrace_id_t, void *); 66 static void sdt_enable(void *, dtrace_id_t, void *); 67 static void sdt_disable(void *, dtrace_id_t, void *); 68 69 static void sdt_load(void); 70 static int sdt_unload(void); 71 static void sdt_create_provider(struct sdt_provider *); 72 static void sdt_create_probe(struct sdt_probe *); 73 static void sdt_kld_load(void *, struct linker_file *); 74 static void sdt_kld_unload_try(void *, struct linker_file *, int *); 75 76 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); 77 78 static dtrace_pattr_t sdt_attr = { 79 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 80 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, 81 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 82 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 83 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 84 }; 85 86 static dtrace_pops_t sdt_pops = { 87 sdt_provide_probes, 88 NULL, 89 sdt_enable, 90 sdt_disable, 91 NULL, 92 NULL, 93 sdt_getargdesc, 94 NULL, 95 NULL, 96 sdt_destroy, 97 }; 98 99 static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 100 101 eventhandler_tag sdt_kld_load_tag; 102 eventhandler_tag sdt_kld_unload_try_tag; 103 104 static void 105 sdt_create_provider(struct sdt_provider *prov) 106 { 107 struct sdt_provider *curr, *newprov; 108 109 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) 110 if (strcmp(prov->name, curr->name) == 0) { 111 /* The provider has already been defined. */ 112 curr->sdt_refs++; 113 return; 114 } 115 116 /* 117 * Make a copy of prov so that we don't lose fields if its module is 118 * unloaded but the provider isn't destroyed. This could happen with 119 * a provider that spans multiple modules. 120 */ 121 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); 122 newprov->name = strdup(prov->name, M_SDT); 123 prov->sdt_refs = newprov->sdt_refs = 1; 124 125 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); 126 127 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, 128 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); 129 prov->id = newprov->id; 130 } 131 132 static void 133 sdt_create_probe(struct sdt_probe *probe) 134 { 135 struct sdt_provider *prov; 136 char mod[DTRACE_MODNAMELEN]; 137 char func[DTRACE_FUNCNAMELEN]; 138 char name[DTRACE_NAMELEN]; 139 const char *from; 140 char *to; 141 size_t len; 142 143 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) 144 if (strcmp(prov->name, probe->prov->name) == 0) 145 break; 146 147 KASSERT(prov != NULL, ("probe defined without a provider")); 148 149 /* If no module name was specified, use the module filename. */ 150 if (*probe->mod == 0) { 151 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); 152 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) 153 mod[len - 3] = '\0'; 154 } else 155 strlcpy(mod, probe->mod, sizeof(mod)); 156 157 /* 158 * Unfortunately this is necessary because the Solaris DTrace 159 * code mixes consts and non-consts with casts to override 160 * the incompatibilies. On FreeBSD, we use strict warnings 161 * in the C compiler, so we have to respect const vs non-const. 162 */ 163 strlcpy(func, probe->func, sizeof(func)); 164 165 from = probe->name; 166 to = name; 167 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 168 len++, from++, to++) { 169 if (from[0] == '_' && from[1] == '_') { 170 *to = '-'; 171 from++; 172 } else 173 *to = *from; 174 } 175 *to = '\0'; 176 177 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 178 return; 179 180 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 181 } 182 183 /* 184 * Probes are created through the SDT module load/unload hook, so this function 185 * has nothing to do. It only exists because the DTrace provider framework 186 * requires one of provide_probes and provide_module to be defined. 187 */ 188 static void 189 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 190 { 191 } 192 193 static void 194 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 195 { 196 struct sdt_probe *probe = parg; 197 198 probe->id = id; 199 probe->sdtp_lf->nenabled++; 200 } 201 202 static void 203 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 204 { 205 struct sdt_probe *probe = parg; 206 207 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 208 209 probe->id = 0; 210 probe->sdtp_lf->nenabled--; 211 } 212 213 static void 214 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 215 { 216 struct sdt_argtype *argtype; 217 struct sdt_probe *probe = parg; 218 219 if (desc->dtargd_ndx >= probe->n_args) { 220 desc->dtargd_ndx = DTRACE_ARGNONE; 221 return; 222 } 223 224 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 225 if (desc->dtargd_ndx == argtype->ndx) { 226 desc->dtargd_mapping = desc->dtargd_ndx; 227 if (argtype->type == NULL) { 228 desc->dtargd_native[0] = '\0'; 229 desc->dtargd_xlate[0] = '\0'; 230 continue; 231 } 232 strlcpy(desc->dtargd_native, argtype->type, 233 sizeof(desc->dtargd_native)); 234 if (argtype->xtype != NULL) 235 strlcpy(desc->dtargd_xlate, argtype->xtype, 236 sizeof(desc->dtargd_xlate)); 237 } 238 } 239 } 240 241 static void 242 sdt_destroy(void *arg, dtrace_id_t id, void *parg) 243 { 244 } 245 246 /* 247 * Called from the kernel linker when a module is loaded, before 248 * dtrace_module_loaded() is called. This is done so that it's possible to 249 * register new providers when modules are loaded. The DTrace framework 250 * explicitly disallows calling into the framework from the provide_module 251 * provider method, so we cannot do this there. 252 */ 253 static void 254 sdt_kld_load(void *arg __unused, struct linker_file *lf) 255 { 256 struct sdt_provider **prov, **begin, **end; 257 struct sdt_probe **probe, **p_begin, **p_end; 258 struct sdt_argtype **argtype, **a_begin, **a_end; 259 260 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 261 NULL) == 0) { 262 for (prov = begin; prov < end; prov++) 263 sdt_create_provider(*prov); 264 } 265 266 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 267 NULL) == 0) { 268 for (probe = p_begin; probe < p_end; probe++) { 269 (*probe)->sdtp_lf = lf; 270 sdt_create_probe(*probe); 271 TAILQ_INIT(&(*probe)->argtype_list); 272 } 273 } 274 275 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 276 NULL) == 0) { 277 for (argtype = a_begin; argtype < a_end; argtype++) { 278 (*argtype)->probe->n_args++; 279 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 280 *argtype, argtype_entry); 281 } 282 } 283 } 284 285 static void 286 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 287 { 288 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 289 290 if (*error != 0) 291 /* We already have an error, so don't do anything. */ 292 return; 293 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 294 NULL)) 295 /* No DTrace providers are declared in this file. */ 296 return; 297 298 /* 299 * Go through all the providers declared in this linker file and 300 * unregister any that aren't declared in another loaded file. 301 */ 302 for (curr = begin; curr < end; curr++) { 303 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 304 if (strcmp(prov->name, (*curr)->name) != 0) 305 continue; 306 307 if (prov->sdt_refs == 1) { 308 if (dtrace_unregister(prov->id) != 0) { 309 *error = 1; 310 return; 311 } 312 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 313 free(prov->name, M_SDT); 314 free(prov, M_SDT); 315 } else 316 prov->sdt_refs--; 317 break; 318 } 319 } 320 } 321 322 static int 323 sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 324 { 325 326 sdt_kld_load(NULL, lf); 327 328 return (0); 329 } 330 331 static void 332 sdt_load() 333 { 334 335 TAILQ_INIT(&sdt_prov_list); 336 337 sdt_probe_func = dtrace_probe; 338 339 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 340 EVENTHANDLER_PRI_ANY); 341 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 342 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 343 344 /* Pick up probes from the kernel and already-loaded linker files. */ 345 linker_file_foreach(sdt_linker_file_cb, NULL); 346 } 347 348 static int 349 sdt_unload() 350 { 351 struct sdt_provider *prov, *tmp; 352 int ret; 353 354 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 355 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 356 357 sdt_probe_func = sdt_probe_stub; 358 359 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 360 ret = dtrace_unregister(prov->id); 361 if (ret != 0) 362 return (ret); 363 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 364 free(prov->name, M_SDT); 365 free(prov, M_SDT); 366 } 367 368 return (0); 369 } 370 371 static int 372 sdt_modevent(module_t mod __unused, int type, void *data __unused) 373 { 374 int error = 0; 375 376 switch (type) { 377 case MOD_LOAD: 378 sdt_load(); 379 break; 380 381 case MOD_UNLOAD: 382 error = sdt_unload(); 383 break; 384 385 case MOD_SHUTDOWN: 386 break; 387 388 default: 389 error = EOPNOTSUPP; 390 break; 391 } 392 393 return (error); 394 } 395 396 DEV_MODULE(sdt, sdt_modevent, NULL); 397 MODULE_VERSION(sdt, 1); 398 MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 399 MODULE_DEPEND(sdt, opensolaris, 1, 1, 1); 400