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