1 /*- 2 * Copyright 2006-2008 John Birrell <jb@FreeBSD.org> 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16 * ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE 17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23 * SUCH DAMAGE. 24 * 25 * $FreeBSD$ 26 * 27 * Backend for the Statically Defined Tracing (SDT) kernel support. This is 28 * required to allow a module to load even though DTrace kernel support may 29 * not be present. A module may be built with SDT probes in it which are 30 * registered and deregistered via SYSINIT/SYSUNINIT. 31 * 32 */ 33 34 #include "opt_kdtrace.h" 35 36 #include <sys/cdefs.h> 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/kernel.h> 40 #include <sys/linker.h> 41 #include <sys/lock.h> 42 #include <sys/proc.h> 43 #include <sys/sx.h> 44 #include <sys/sdt.h> 45 46 /* 47 * This is the list of statically defined tracing providers. 48 */ 49 static TAILQ_HEAD(sdt_provider_list_head, sdt_provider) sdt_provider_list; 50 51 /* 52 * Mutex to serialise access to the SDT provider list. 53 */ 54 static struct sx sdt_sx; 55 56 /* 57 * Hook for the DTrace probe function. The 'sdt' provider will set this 58 * to dtrace_probe when it loads. 59 */ 60 sdt_probe_func_t sdt_probe_func = sdt_probe_stub; 61 62 static sdt_provider_listall_func_t sdt_provider_register_func = NULL; 63 static sdt_provider_listall_func_t sdt_provider_deregister_func = NULL; 64 static sdt_probe_listall_func_t sdt_probe_register_func = NULL; 65 66 static void *sdt_provider_register_arg; 67 static void *sdt_provider_deregister_arg; 68 static void *sdt_probe_register_arg; 69 70 static int sdt_provider_listall_locked(sdt_provider_listall_func_t, void *); 71 72 /* 73 * This is a stub for probe calls in case kernel DTrace support isn't 74 * compiled in. It should never get called because there is no DTrace 75 * support to enable it. 76 */ 77 void 78 sdt_probe_stub(uint32_t id, uintptr_t arg0, uintptr_t arg1, 79 uintptr_t arg2, uintptr_t arg3, uintptr_t arg4) 80 { 81 printf("sdt_probe_stub: Why did this get called?\n"); 82 } 83 84 /* 85 * Called from SYSINIT to register a provider. 86 */ 87 void 88 sdt_provider_register(void *arg) 89 { 90 struct sdt_provider *prov = arg; 91 92 sx_xlock(&sdt_sx); 93 94 TAILQ_INSERT_TAIL(&sdt_provider_list, prov, prov_entry); 95 96 TAILQ_INIT(&prov->probe_list); 97 98 if (sdt_provider_register_func != NULL) 99 sdt_provider_register_func(prov, sdt_provider_register_arg); 100 101 sx_xunlock(&sdt_sx); 102 } 103 104 /* 105 * Called from SYSUNINIT to de-register a provider. 106 */ 107 void 108 sdt_provider_deregister(void *arg) 109 { 110 struct sdt_provider *prov = arg; 111 112 sx_xlock(&sdt_sx); 113 114 TAILQ_REMOVE(&sdt_provider_list, prov, prov_entry); 115 116 if (sdt_provider_deregister_func != NULL) 117 sdt_provider_deregister_func(prov, sdt_provider_deregister_arg); 118 119 sx_xunlock(&sdt_sx); 120 } 121 122 /* 123 * Called from SYSINIT to register a statically defined trace probe. 124 */ 125 void 126 sdt_probe_register(void *arg) 127 { 128 struct sdt_probe *probe = arg; 129 130 /* 131 * Check the reference structure version. Only version 1 is 132 * supported at the moment. 133 */ 134 if (probe->version != sizeof(struct sdt_probe)) { 135 printf("%s:%s:%s has version %d when %d required\n", probe->mod, probe->func, probe->name, probe->version, (int) sizeof(struct sdt_probe)); 136 return; 137 } 138 139 sx_xlock(&sdt_sx); 140 141 TAILQ_INSERT_TAIL(&probe->prov->probe_list, probe, probe_entry); 142 143 TAILQ_INIT(&probe->argtype_list); 144 145 probe->state = SDT_INIT; 146 147 if (sdt_probe_register_func != NULL) 148 sdt_probe_register_func(probe, sdt_provider_register_arg); 149 150 sx_xunlock(&sdt_sx); 151 } 152 153 /* 154 * Called from SYSUNINIT to de-register a statically defined trace probe. 155 */ 156 void 157 sdt_probe_deregister(void *arg) 158 { 159 struct sdt_probe *probe = arg; 160 161 sx_xlock(&sdt_sx); 162 163 if (probe->state == SDT_INIT) { 164 TAILQ_REMOVE(&probe->prov->probe_list, probe, probe_entry); 165 probe->state = SDT_UNINIT; 166 } 167 168 sx_xunlock(&sdt_sx); 169 } 170 171 /* 172 * Called from SYSINIT to register a statically defined trace probe argument. 173 */ 174 void 175 sdt_argtype_register(void *arg) 176 { 177 struct sdt_argtype *argtype = arg; 178 179 sx_xlock(&sdt_sx); 180 181 TAILQ_INSERT_TAIL(&argtype->probe->argtype_list, argtype, argtype_entry); 182 183 argtype->probe->n_args++; 184 185 sx_xunlock(&sdt_sx); 186 } 187 188 /* 189 * Called from SYSUNINIT to de-register a statically defined trace probe argument. 190 */ 191 void 192 sdt_argtype_deregister(void *arg) 193 { 194 struct sdt_argtype *argtype = arg; 195 196 sx_xlock(&sdt_sx); 197 198 TAILQ_REMOVE(&argtype->probe->argtype_list, argtype, argtype_entry); 199 200 sx_xunlock(&sdt_sx); 201 } 202 203 static void 204 sdt_init(void *arg) 205 { 206 sx_init_flags(&sdt_sx, "Statically Defined Tracing", SX_NOWITNESS); 207 208 TAILQ_INIT(&sdt_provider_list); 209 } 210 211 SYSINIT(sdt, SI_SUB_KDTRACE, SI_ORDER_FIRST, sdt_init, NULL); 212 213 static void 214 sdt_uninit(void *arg) 215 { 216 sx_destroy(&sdt_sx); 217 } 218 219 SYSUNINIT(sdt, SI_SUB_KDTRACE, SI_ORDER_FIRST, sdt_uninit, NULL); 220 221 /* 222 * List statically defined tracing providers. 223 */ 224 int 225 sdt_provider_listall(sdt_provider_listall_func_t callback_func, void *arg) 226 { 227 int error; 228 229 sx_xlock(&sdt_sx); 230 error = sdt_provider_listall_locked(callback_func, arg); 231 sx_xunlock(&sdt_sx); 232 233 return (error); 234 } 235 236 static int 237 sdt_provider_listall_locked(sdt_provider_listall_func_t callback_func, 238 void *arg) 239 { 240 int error = 0; 241 struct sdt_provider *prov; 242 243 sx_assert(&sdt_sx, SX_XLOCKED); 244 245 TAILQ_FOREACH(prov, &sdt_provider_list, prov_entry) { 246 if ((error = callback_func(prov, arg)) != 0) 247 break; 248 } 249 250 return (error); 251 } 252 253 /* 254 * List statically defined tracing probes. 255 */ 256 int 257 sdt_probe_listall(struct sdt_provider *prov, 258 sdt_probe_listall_func_t callback_func,void *arg) 259 { 260 int error = 0; 261 int locked; 262 struct sdt_probe *probe; 263 264 locked = sx_xlocked(&sdt_sx); 265 if (!locked) 266 sx_xlock(&sdt_sx); 267 268 TAILQ_FOREACH(probe, &prov->probe_list, probe_entry) { 269 if ((error = callback_func(probe, arg)) != 0) 270 break; 271 } 272 273 if (!locked) 274 sx_xunlock(&sdt_sx); 275 276 return (error); 277 } 278 279 /* 280 * List statically defined tracing probe arguments. 281 */ 282 int 283 sdt_argtype_listall(struct sdt_probe *probe, 284 sdt_argtype_listall_func_t callback_func,void *arg) 285 { 286 int error = 0; 287 int locked; 288 struct sdt_argtype *argtype; 289 290 locked = sx_xlocked(&sdt_sx); 291 if (!locked) 292 sx_xlock(&sdt_sx); 293 294 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) { 295 if ((error = callback_func(argtype, arg)) != 0) 296 break; 297 } 298 299 if (!locked) 300 sx_xunlock(&sdt_sx); 301 302 return (error); 303 } 304 305 void sdt_register_callbacks(sdt_provider_listall_func_t register_prov, 306 void *reg_prov_arg, sdt_provider_listall_func_t deregister_prov, 307 void *dereg_prov_arg, sdt_probe_listall_func_t register_probe, 308 void * reg_probe_arg) 309 { 310 311 sx_xlock(&sdt_sx); 312 sdt_provider_register_func = register_prov; 313 sdt_provider_deregister_func = deregister_prov; 314 sdt_probe_register_func = register_probe; 315 316 sdt_provider_register_arg = reg_prov_arg; 317 sdt_provider_deregister_arg = dereg_prov_arg; 318 sdt_probe_register_arg = reg_probe_arg; 319 320 sdt_provider_listall_locked(register_prov, reg_prov_arg); 321 sx_xunlock(&sdt_sx); 322 } 323 324 void sdt_deregister_callbacks(void) 325 { 326 327 sx_xlock(&sdt_sx); 328 sdt_provider_listall_locked(sdt_provider_deregister_func, 329 sdt_provider_deregister_arg); 330 331 sdt_provider_register_func = NULL; 332 sdt_provider_deregister_func = NULL; 333 sdt_probe_register_func = NULL; 334 335 sdt_provider_register_arg = NULL; 336 sdt_provider_deregister_arg = NULL; 337 sdt_probe_register_arg = NULL; 338 sx_xunlock(&sdt_sx); 339 } 340