sdt.c revision 289803
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 289803 2015-10-23 07:57:21Z 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)); 172 173 from = probe->name; 174 to = name; 175 for (len = 0; len < (sizeof(name) - 1) && *from != '\0'; 176 len++, from++, to++) { 177 if (from[0] == '_' && from[1] == '_') { 178 *to = '-'; 179 from++; 180 } else 181 *to = *from; 182 } 183 *to = '\0'; 184 185 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE) 186 return; 187 188 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe); 189} 190 191/* 192 * Probes are created through the SDT module load/unload hook, so this function 193 * has nothing to do. It only exists because the DTrace provider framework 194 * requires one of provide_probes and provide_module to be defined. 195 */ 196static void 197sdt_provide_probes(void *arg, dtrace_probedesc_t *desc) 198{ 199} 200 201static void 202sdt_enable(void *arg __unused, dtrace_id_t id, void *parg) 203{ 204 struct sdt_probe *probe = parg; 205 206 probe->id = id; 207 probe->sdtp_lf->nenabled++; 208} 209 210static void 211sdt_disable(void *arg __unused, dtrace_id_t id, void *parg) 212{ 213 struct sdt_probe *probe = parg; 214 215 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); 216 217 probe->id = 0; 218 probe->sdtp_lf->nenabled--; 219} 220 221static void 222sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc) 223{ 224 struct sdt_argtype *argtype; 225 struct sdt_probe *probe = parg; 226 227 if (desc->dtargd_ndx >= probe->n_args) { 228 desc->dtargd_ndx = DTRACE_ARGNONE; 229 return; 230 } 231 232 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 233 if (desc->dtargd_ndx == argtype->ndx) { 234 desc->dtargd_mapping = desc->dtargd_ndx; 235 if (argtype->type == NULL) { 236 desc->dtargd_native[0] = '\0'; 237 desc->dtargd_xlate[0] = '\0'; 238 continue; 239 } 240 strlcpy(desc->dtargd_native, argtype->type, 241 sizeof(desc->dtargd_native)); 242 if (argtype->xtype != NULL) 243 strlcpy(desc->dtargd_xlate, argtype->xtype, 244 sizeof(desc->dtargd_xlate)); 245 } 246 } 247} 248 249static void 250sdt_destroy(void *arg, dtrace_id_t id, void *parg) 251{ 252} 253 254/* 255 * Called from the kernel linker when a module is loaded, before 256 * dtrace_module_loaded() is called. This is done so that it's possible to 257 * register new providers when modules are loaded. The DTrace framework 258 * explicitly disallows calling into the framework from the provide_module 259 * provider method, so we cannot do this there. 260 */ 261static void 262sdt_kld_load(void *arg __unused, struct linker_file *lf) 263{ 264 struct sdt_provider **prov, **begin, **end; 265 struct sdt_probe **probe, **p_begin, **p_end; 266 struct sdt_argtype **argtype, **a_begin, **a_end; 267 268 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 269 NULL) == 0) { 270 for (prov = begin; prov < end; prov++) 271 sdt_create_provider(*prov); 272 } 273 274 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end, 275 NULL) == 0) { 276 for (probe = p_begin; probe < p_end; probe++) { 277 (*probe)->sdtp_lf = lf; 278 sdt_create_probe(*probe); 279 TAILQ_INIT(&(*probe)->argtype_list); 280 } 281 } 282 283 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end, 284 NULL) == 0) { 285 for (argtype = a_begin; argtype < a_end; argtype++) { 286 (*argtype)->probe->n_args++; 287 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list, 288 *argtype, argtype_entry); 289 } 290 } 291} 292 293static void 294sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error) 295{ 296 struct sdt_provider *prov, **curr, **begin, **end, *tmp; 297 298 if (*error != 0) 299 /* We already have an error, so don't do anything. */ 300 return; 301 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end, 302 NULL)) 303 /* No DTrace providers are declared in this file. */ 304 return; 305 306 /* 307 * Go through all the providers declared in this linker file and 308 * unregister any that aren't declared in another loaded file. 309 */ 310 for (curr = begin; curr < end; curr++) { 311 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 312 if (strcmp(prov->name, (*curr)->name) != 0) 313 continue; 314 315 if (prov->sdt_refs == 1) { 316 if (dtrace_unregister(prov->id) != 0) { 317 *error = 1; 318 return; 319 } 320 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 321 free(prov->name, M_SDT); 322 free(prov, M_SDT); 323 } else 324 prov->sdt_refs--; 325 break; 326 } 327 } 328} 329 330static int 331sdt_linker_file_cb(linker_file_t lf, void *arg __unused) 332{ 333 334 sdt_kld_load(NULL, lf); 335 336 return (0); 337} 338 339static void 340sdt_load() 341{ 342 343 TAILQ_INIT(&sdt_prov_list); 344 345 sdt_probe_func = dtrace_probe; 346 347 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL, 348 EVENTHANDLER_PRI_ANY); 349 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try, 350 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY); 351 352 /* Pick up probes from the kernel and already-loaded linker files. */ 353 linker_file_foreach(sdt_linker_file_cb, NULL); 354} 355 356static int 357sdt_unload() 358{ 359 struct sdt_provider *prov, *tmp; 360 int ret; 361 362 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag); 363 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag); 364 365 sdt_probe_func = sdt_probe_stub; 366 367 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) { 368 ret = dtrace_unregister(prov->id); 369 if (ret != 0) 370 return (ret); 371 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry); 372 free(prov->name, M_SDT); 373 free(prov, M_SDT); 374 } 375 376 return (0); 377} 378 379static int 380sdt_modevent(module_t mod __unused, int type, void *data __unused) 381{ 382 int error = 0; 383 384 switch (type) { 385 case MOD_LOAD: 386 sdt_load(); 387 break; 388 389 case MOD_UNLOAD: 390 error = sdt_unload(); 391 break; 392 393 case MOD_SHUTDOWN: 394 break; 395 396 default: 397 error = EOPNOTSUPP; 398 break; 399 } 400 401 return (error); 402} 403 404DEV_MODULE(sdt, sdt_modevent, NULL); 405MODULE_VERSION(sdt, 1); 406MODULE_DEPEND(sdt, dtrace, 1, 1, 1); 407