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 "opt_kdtrace.h" 43 44 #include <sys/cdefs.h> 45 #include <sys/param.h> 46 #include <sys/systm.h> 47 48 #include <sys/conf.h> 49 #include <sys/eventhandler.h> 50 #include <sys/kernel.h> 51 #include <sys/limits.h> 52 #include <sys/linker.h> 53 #include <sys/linker_set.h> 54 #include <sys/lock.h> 55 #include <sys/malloc.h> 56 #include <sys/module.h> 57 #include <sys/mutex.h> 58 #include <sys/queue.h> 59 #include <sys/sdt.h> 60 61 #include <sys/dtrace.h> 62 #include <sys/dtrace_bsd.h> 63 64 /* DTrace methods. */ 65 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); 66 static void sdt_provide_probes(void *, dtrace_probedesc_t *); 67 static void sdt_destroy(void *, dtrace_id_t, void *); 68 static void sdt_enable(void *, dtrace_id_t, void *); 69 static void sdt_disable(void *, dtrace_id_t, void *); 70 71 static void sdt_load(void); 72 static int sdt_unload(void); 73 static void sdt_create_provider(struct sdt_provider *); 74 static void sdt_create_probe(struct sdt_probe *); 75 static void sdt_kld_load(void *, struct linker_file *); 76 static void sdt_kld_unload_try(void *, struct linker_file *, int *); 77 78 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); 79 80 static dtrace_pattr_t sdt_attr = { 81 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 82 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, 83 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 84 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, 85 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA }, 86 }; 87 88 static dtrace_pops_t sdt_pops = { 89 sdt_provide_probes, 90 NULL, 91 sdt_enable, 92 sdt_disable, 93 NULL, 94 NULL, 95 sdt_getargdesc, 96 NULL, 97 NULL, 98 sdt_destroy, 99 }; 100 101 static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 102 103 eventhandler_tag sdt_kld_load_tag; 104 eventhandler_tag sdt_kld_unload_try_tag; 105 106 static void 107 sdt_create_provider(struct sdt_provider *prov) 108 { 109 struct sdt_provider *curr, *newprov; 110 111 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry) 112 if (strcmp(prov->name, curr->name) == 0) { 113 /* The provider has already been defined. */ 114 curr->sdt_refs++; 115 return; 116 } 117 118 /* 119 * Make a copy of prov so that we don't lose fields if its module is 120 * unloaded but the provider isn't destroyed. This could happen with 121 * a provider that spans multiple modules. 122 */ 123 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO); 124 newprov->name = strdup(prov->name, M_SDT); 125 prov->sdt_refs = newprov->sdt_refs = 1; 126 127 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry); 128 129 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL, 130 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id); 131 prov->id = newprov->id; 132 } 133 134 static void 135 sdt_create_probe(struct sdt_probe *probe) 136 { 137 struct sdt_provider *prov; 138 char mod[DTRACE_MODNAMELEN]; 139 char func[DTRACE_FUNCNAMELEN]; 140 char name[DTRACE_NAMELEN]; 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 strlcpy(name, probe->name, sizeof(name)); 165 166 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 167 return; 168 169 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 170 } 171 172 /* 173 * Probes are created through the SDT module load/unload hook, so this function 174 * has nothing to do. It only exists because the DTrace provider framework 175 * requires one of provide_probes and provide_module to be defined. 176 */ 177 static void 178 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 179 { 180 } 181 182 static void 183 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 184 { 185 struct sdt_probe *probe = parg; 186 187 probe->id = id; 188 probe->sdtp_lf->nenabled++; 189 } 190 191 static void 192 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 193 { 194 struct sdt_probe *probe = parg; 195 196 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 197 198 probe->id = 0; 199 probe->sdtp_lf->nenabled--; 200 } 201 202 static void 203 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 204 { 205 struct sdt_argtype *argtype; 206 struct sdt_probe *probe = parg; 207 208 if (desc->dtargd_ndx >= probe->n_args) { 209 desc->dtargd_ndx = DTRACE_ARGNONE; 210 return; 211 } 212 213 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 214 if (desc->dtargd_ndx == argtype->ndx) { 215 desc->dtargd_mapping = desc->dtargd_ndx; 216 if (argtype->type == NULL) { 217 desc->dtargd_native[0] = '\0'; 218 desc->dtargd_xlate[0] = '\0'; 219 continue; 220 } 221 strlcpy(desc->dtargd_native, argtype->type, 222 sizeof(desc->dtargd_native)); 223 if (argtype->xtype != NULL) 224 strlcpy(desc->dtargd_xlate, argtype->xtype, 225 sizeof(desc->dtargd_xlate)); 226 } 227 } 228 } 229 230 static void 231 sdt_destroy(void *arg, dtrace_id_t id, void *parg) 232 { 233 } 234 235 /* 236 * Called from the kernel linker when a module is loaded, before 237 * dtrace_module_loaded() is called. This is done so that it's possible to 238 * register new providers when modules are loaded. The DTrace framework 239 * explicitly disallows calling into the framework from the provide_module 240 * provider method, so we cannot do this there. 241 */ 242 static void 243 sdt_kld_load(void *arg __unused, struct linker_file *lf) 244 { 245 struct sdt_provider **prov, **begin, **end; 246 struct sdt_probe **probe, **p_begin, **p_end; 247 struct sdt_argtype **argtype, **a_begin, **a_end; 248 249 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, NULL)) 250 return; 251 for (prov = begin; prov < end; prov++) 252 sdt_create_provider(*prov); 253 254 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 255 NULL)) 256 return; 257 for (probe = p_begin; probe < p_end; probe++) { 258 (*probe)->sdtp_lf = lf; 259 sdt_create_probe(*probe); 260 TAILQ_INIT(&(*probe)->argtype_list); 261 } 262 263 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 264 NULL)) 265 return; 266 for (argtype = a_begin; argtype < a_end; argtype++) { 267 (*argtype)->probe->n_args++; 268 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, *argtype, 269 argtype_entry); 270 } 271 } 272 273 static void 274 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 275 { 276 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 277 278 if (*error != 0) 279 /* We already have an error, so don't do anything. */ 280 return; 281 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 282 NULL)) 283 /* No DTrace providers are declared in this file. */ 284 return; 285 286 /* 287 * Go through all the providers declared in this linker file and 288 * unregister any that aren't declared in another loaded file. 289 */ 290 for (curr = begin; curr < end; curr++) { 291 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 292 if (strcmp(prov->name, (*curr)->name) != 0) 293 continue; 294 295 if (prov->sdt_refs == 1) { 296 if (dtrace_unregister(prov->id) != 0) { 297 *error = 1; 298 return; 299 } 300 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 301 free(prov->name, M_SDT); 302 free(prov, M_SDT); 303 } else 304 prov->sdt_refs--; 305 break; 306 } 307 } 308 } 309 310 static int 311 sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 312 { 313 314 sdt_kld_load(NULL, lf); 315 316 return (0); 317 } 318 319 static void 320 sdt_load() 321 { 322 323 TAILQ_INIT(&sdt_prov_list); 324 325 sdt_probe_func = dtrace_probe; 326 327 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 328 EVENTHANDLER_PRI_ANY); 329 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 330 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 331 332 /* Pick up probes from the kernel and already-loaded linker files. */ 333 linker_file_foreach(sdt_linker_file_cb, NULL); 334 } 335 336 static int 337 sdt_unload() 338 { 339 struct sdt_provider *prov, *tmp; 340 int ret; 341 342 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 343 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 344 345 sdt_probe_func = sdt_probe_stub; 346 347 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 348 ret = dtrace_unregister(prov->id); 349 if (ret != 0) 350 return (ret); 351 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 352 free(prov->name, M_SDT); 353 free(prov, M_SDT); 354 } 355 356 return (0); 357 } 358 359 static int 360 sdt_modevent(module_t mod __unused, int type, void *data __unused) 361 { 362 int error = 0; 363 364 switch (type) { 365 case MOD_LOAD: 366 sdt_load(); 367 break; 368 369 case MOD_UNLOAD: 370 error = sdt_unload(); 371 break; 372 373 case MOD_SHUTDOWN: 374 break; 375 376 default: 377 error = EOPNOTSUPP; 378 break; 379 } 380 381 return (error); 382 } 383 384 DEV_MODULE(sdt, sdt_modevent, NULL); 385 MODULE_VERSION(sdt, 1); 386 MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 387 MODULE_DEPEND(sdt, opensolaris, 1, 1, 1); 388