sdt.c revision 289809
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: stable/10/sys/cddl/dev/sdt/sdt.c 289809 2015-10-23 08:15:53Z avg $ 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. */ 65static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *); 66static void sdt_provide_probes(void *, dtrace_probedesc_t *); 67static void sdt_destroy(void *, dtrace_id_t, void *); 68static void sdt_enable(void *, dtrace_id_t, void *); 69static void sdt_disable(void *, dtrace_id_t, void *); 70 71static void sdt_load(void); 72static int sdt_unload(void); 73static void sdt_create_provider(struct sdt_provider *); 74static void sdt_create_probe(struct sdt_probe *); 75static void sdt_kld_load(void *, struct linker_file *); 76static void sdt_kld_unload_try(void *, struct linker_file *, int *); 77 78static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); 79 80static 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 88static 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 101static TAILQ_HEAD(, sdt_provider) sdt_prov_list; 102 103static eventhandler_tag sdt_kld_load_tag; 104static eventhandler_tag sdt_kld_unload_try_tag; 105 106static void 107sdt_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 134static void 135sdt_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 const char *from; 142 char *to; 143 size_t len; 144 145 if (probe->version != (int)sizeof(*probe)) { 146 printf("ignoring probe %p, version %u expected %u\n", 147 probe, probe->version, (int)sizeof(*probe)); 148 return; 149 } 150 151 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry) 152 if (strcmp(prov->name, probe->prov->name) == 0) 153 break; 154 155 KASSERT(prov != NULL, ("probe defined without a provider")); 156 157 /* If no module name was specified, use the module filename. */ 158 if (*probe->mod == 0) { 159 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod)); 160 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0) 161 mod[len - 3] = '\0'; 162 } else 163 strlcpy(mod, probe->mod, sizeof(mod)); 164 165 /* 166 * Unfortunately this is necessary because the Solaris DTrace 167 * code mixes consts and non-consts with casts to override 168 * the incompatibilies. On FreeBSD, we use strict warnings 169 * in the C compiler, so we have to respect const vs non-const. 170 */ 171 strlcpy(func, probe->func, sizeof(func)); 172 if (func[0] == '\0') 173 strcpy(func, "none"); 174 175 from = probe->name; 176 to = name; 177 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 178 len++, from++, to++) { 179 if (from[0] == '_' && from[1] == '_') { 180 *to = '-'; 181 from++; 182 } else 183 *to = *from; 184 } 185 *to = '\0'; 186 187 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 188 return; 189 190 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 191} 192 193/* 194 * Probes are created through the SDT module load/unload hook, so this function 195 * has nothing to do. It only exists because the DTrace provider framework 196 * requires one of provide_probes and provide_module to be defined. 197 */ 198static void 199sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 200{ 201} 202 203static void 204sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 205{ 206 struct sdt_probe *probe = parg; 207 208 probe->id = id; 209 probe->sdtp_lf->nenabled++; 210} 211 212static void 213sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 214{ 215 struct sdt_probe *probe = parg; 216 217 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 218 219 probe->id = 0; 220 probe->sdtp_lf->nenabled--; 221} 222 223static void 224sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 225{ 226 struct sdt_argtype *argtype; 227 struct sdt_probe *probe = parg; 228 229 if (desc->dtargd_ndx >= probe->n_args) { 230 desc->dtargd_ndx = DTRACE_ARGNONE; 231 return; 232 } 233 234 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 235 if (desc->dtargd_ndx == argtype->ndx) { 236 desc->dtargd_mapping = desc->dtargd_ndx; 237 if (argtype->type == NULL) { 238 desc->dtargd_native[0] = '\0'; 239 desc->dtargd_xlate[0] = '\0'; 240 continue; 241 } 242 strlcpy(desc->dtargd_native, argtype->type, 243 sizeof(desc->dtargd_native)); 244 if (argtype->xtype != NULL) 245 strlcpy(desc->dtargd_xlate, argtype->xtype, 246 sizeof(desc->dtargd_xlate)); 247 } 248 } 249} 250 251static void 252sdt_destroy(void *arg, dtrace_id_t id, void *parg) 253{ 254} 255 256/* 257 * Called from the kernel linker when a module is loaded, before 258 * dtrace_module_loaded() is called. This is done so that it's possible to 259 * register new providers when modules are loaded. The DTrace framework 260 * explicitly disallows calling into the framework from the provide_module 261 * provider method, so we cannot do this there. 262 */ 263static void 264sdt_kld_load(void *arg __unused, struct linker_file *lf) 265{ 266 struct sdt_provider **prov, **begin, **end; 267 struct sdt_probe **probe, **p_begin, **p_end; 268 struct sdt_argtype **argtype, **a_begin, **a_end; 269 270 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 271 NULL) == 0) { 272 for (prov = begin; prov < end; prov++) 273 sdt_create_provider(*prov); 274 } 275 276 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 277 NULL) == 0) { 278 for (probe = p_begin; probe < p_end; probe++) { 279 (*probe)->sdtp_lf = lf; 280 sdt_create_probe(*probe); 281 TAILQ_INIT(&(*probe)->argtype_list); 282 } 283 } 284 285 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 286 NULL) == 0) { 287 for (argtype = a_begin; argtype < a_end; argtype++) { 288 (*argtype)->probe->n_args++; 289 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 290 *argtype, argtype_entry); 291 } 292 } 293} 294 295static void 296sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 297{ 298 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 299 300 if (*error != 0) 301 /* We already have an error, so don't do anything. */ 302 return; 303 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 304 NULL)) 305 /* No DTrace providers are declared in this file. */ 306 return; 307 308 /* 309 * Go through all the providers declared in this linker file and 310 * unregister any that aren't declared in another loaded file. 311 */ 312 for (curr = begin; curr < end; curr++) { 313 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 314 if (strcmp(prov->name, (*curr)->name) != 0) 315 continue; 316 317 if (prov->sdt_refs == 1) { 318 if (dtrace_unregister(prov->id) != 0) { 319 *error = 1; 320 return; 321 } 322 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 323 free(prov->name, M_SDT); 324 free(prov, M_SDT); 325 } else 326 prov->sdt_refs--; 327 break; 328 } 329 } 330} 331 332static int 333sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 334{ 335 336 sdt_kld_load(NULL, lf); 337 338 return (0); 339} 340 341static void 342sdt_load() 343{ 344 345 TAILQ_INIT(&sdt_prov_list); 346 347 sdt_probe_func = dtrace_probe; 348 349 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 350 EVENTHANDLER_PRI_ANY); 351 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 352 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 353 354 /* Pick up probes from the kernel and already-loaded linker files. */ 355 linker_file_foreach(sdt_linker_file_cb, NULL); 356} 357 358static int 359sdt_unload() 360{ 361 struct sdt_provider *prov, *tmp; 362 int ret; 363 364 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 365 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 366 367 sdt_probe_func = sdt_probe_stub; 368 369 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 370 ret = dtrace_unregister(prov->id); 371 if (ret != 0) 372 return (ret); 373 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 374 free(prov->name, M_SDT); 375 free(prov, M_SDT); 376 } 377 378 return (0); 379} 380 381static int 382sdt_modevent(module_t mod __unused, int type, void *data __unused) 383{ 384 int error = 0; 385 386 switch (type) { 387 case MOD_LOAD: 388 sdt_load(); 389 break; 390 391 case MOD_UNLOAD: 392 error = sdt_unload(); 393 break; 394 395 case MOD_SHUTDOWN: 396 break; 397 398 default: 399 error = EOPNOTSUPP; 400 break; 401 } 402 403 return (error); 404} 405 406DEV_MODULE(sdt, sdt_modevent, NULL); 407MODULE_VERSION(sdt, 1); 408MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 409