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 */
24
25 /*
26 * This file contains a reimplementation of the statically-defined tracing (SDT)
27 * framework for DTrace. Probes and SDT providers are defined using the macros
28 * in sys/sdt.h, which append all the needed structures to linker sets. When
29 * this module is loaded, it iterates over all of the loaded modules and
30 * registers probes and providers with the DTrace framework based on the
31 * contents of these linker sets.
32 *
33 * A list of SDT providers is maintained here since a provider may span multiple
34 * modules. When a kernel module is unloaded, a provider defined in that module
35 * is unregistered only if no other modules refer to it. The DTrace framework is
36 * responsible for destroying individual probes when a kernel module is
37 * unloaded; in particular, probes may not span multiple kernel modules.
38 */
39
40 #include <sys/param.h>
41 #include <sys/systm.h>
42
43 #include <sys/conf.h>
44 #include <sys/endian.h>
45 #include <sys/eventhandler.h>
46 #include <sys/kernel.h>
47 #include <sys/limits.h>
48 #include <sys/linker.h>
49 #include <sys/linker_set.h>
50 #include <sys/lock.h>
51 #include <sys/lockstat.h>
52 #include <sys/malloc.h>
53 #include <sys/module.h>
54 #include <sys/mutex.h>
55 #include <sys/queue.h>
56 #include <sys/sdt.h>
57
58 #include <sys/dtrace.h>
59 #include <sys/dtrace_bsd.h>
60
61 /* DTrace methods. */
62 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *);
63 static void sdt_provide_probes(void *, dtrace_probedesc_t *);
64 static void sdt_destroy(void *, dtrace_id_t, void *);
65 static void sdt_enable(void *, dtrace_id_t, void *);
66 static void sdt_disable(void *, dtrace_id_t, void *);
67
68 static void sdt_load(void);
69 static int sdt_unload(void);
70 static void sdt_create_provider(struct sdt_provider *);
71 static void sdt_create_probe(struct sdt_probe *);
72 static void sdt_kld_load(void *, struct linker_file *);
73 static void sdt_kld_unload_try(void *, struct linker_file *, int *);
74
75 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers");
76
77 static int sdt_probes_enabled_count;
78 static int lockstat_enabled_count;
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 .dtps_provide = sdt_provide_probes,
90 .dtps_provide_module = NULL,
91 .dtps_enable = sdt_enable,
92 .dtps_disable = sdt_disable,
93 .dtps_suspend = NULL,
94 .dtps_resume = NULL,
95 .dtps_getargdesc = sdt_getargdesc,
96 .dtps_getargval = NULL,
97 .dtps_usermode = NULL,
98 .dtps_destroy = sdt_destroy,
99 };
100
101 static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
102
103 static eventhandler_tag sdt_kld_load_tag;
104 static eventhandler_tag sdt_kld_unload_try_tag;
105
106 static void
sdt_create_provider(struct sdt_provider * prov)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
sdt_create_probe(struct sdt_probe * probe)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 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 */
198 static void
sdt_provide_probes(void * arg,dtrace_probedesc_t * desc)199 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc)
200 {
201 }
202
203 static void
sdt_enable(void * arg __unused,dtrace_id_t id,void * parg)204 sdt_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 if (strcmp(probe->prov->name, "lockstat") == 0) {
211 lockstat_enabled_count++;
212 if (lockstat_enabled_count == 1)
213 lockstat_enabled = true;
214 }
215 sdt_probes_enabled_count++;
216 if (sdt_probes_enabled_count == 1)
217 sdt_probes_enabled = true;
218 }
219
220 static void
sdt_disable(void * arg __unused,dtrace_id_t id,void * parg)221 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg)
222 {
223 struct sdt_probe *probe = parg;
224
225 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled"));
226
227 sdt_probes_enabled_count--;
228 if (sdt_probes_enabled_count == 0)
229 sdt_probes_enabled = false;
230 if (strcmp(probe->prov->name, "lockstat") == 0) {
231 lockstat_enabled_count--;
232 if (lockstat_enabled_count == 0)
233 lockstat_enabled = false;
234 }
235 probe->id = 0;
236 probe->sdtp_lf->nenabled--;
237 }
238
239 static void
sdt_getargdesc(void * arg,dtrace_id_t id,void * parg,dtrace_argdesc_t * desc)240 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc)
241 {
242 struct sdt_argtype *argtype;
243 struct sdt_probe *probe = parg;
244
245 if (desc->dtargd_ndx >= probe->n_args) {
246 desc->dtargd_ndx = DTRACE_ARGNONE;
247 return;
248 }
249
250 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) {
251 if (desc->dtargd_ndx == argtype->ndx) {
252 desc->dtargd_mapping = desc->dtargd_ndx;
253 if (argtype->type == NULL) {
254 desc->dtargd_native[0] = '\0';
255 desc->dtargd_xlate[0] = '\0';
256 continue;
257 }
258 strlcpy(desc->dtargd_native, argtype->type,
259 sizeof(desc->dtargd_native));
260 if (argtype->xtype != NULL)
261 strlcpy(desc->dtargd_xlate, argtype->xtype,
262 sizeof(desc->dtargd_xlate));
263 }
264 }
265 }
266
267 static void
sdt_destroy(void * arg,dtrace_id_t id,void * parg)268 sdt_destroy(void *arg, dtrace_id_t id, void *parg)
269 {
270 }
271
272 static void
sdt_kld_load_providers(struct linker_file * lf)273 sdt_kld_load_providers(struct linker_file *lf)
274 {
275 struct sdt_provider **prov, **begin, **end;
276
277 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
278 NULL) == 0) {
279 for (prov = begin; prov < end; prov++)
280 sdt_create_provider(*prov);
281 }
282 }
283
284 static void
sdt_kld_load_probes(struct linker_file * lf)285 sdt_kld_load_probes(struct linker_file *lf)
286 {
287 struct sdt_probe **probe, **p_begin, **p_end;
288 struct sdt_argtype **argtype, **a_begin, **a_end;
289
290 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end,
291 NULL) == 0) {
292 for (probe = p_begin; probe < p_end; probe++) {
293 (*probe)->sdtp_lf = lf;
294 sdt_create_probe(*probe);
295 TAILQ_INIT(&(*probe)->argtype_list);
296 }
297 }
298
299 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end,
300 NULL) == 0) {
301 for (argtype = a_begin; argtype < a_end; argtype++) {
302 (*argtype)->probe->n_args++;
303 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list,
304 *argtype, argtype_entry);
305 }
306 }
307 }
308
309 /*
310 * Called from the kernel linker when a module is loaded, before
311 * dtrace_module_loaded() is called. This is done so that it's possible to
312 * register new providers when modules are loaded. The DTrace framework
313 * explicitly disallows calling into the framework from the provide_module
314 * provider method, so we cannot do this there.
315 */
316 static void
sdt_kld_load(void * arg __unused,struct linker_file * lf)317 sdt_kld_load(void *arg __unused, struct linker_file *lf)
318 {
319 sdt_kld_load_providers(lf);
320 sdt_kld_load_probes(lf);
321 }
322
323 static void
sdt_kld_unload_try(void * arg __unused,struct linker_file * lf,int * error)324 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
325 {
326 struct sdt_provider *prov, **curr, **begin, **end, *tmp;
327
328 if (*error != 0)
329 /* We already have an error, so don't do anything. */
330 return;
331 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
332 NULL))
333 /* No DTrace providers are declared in this file. */
334 return;
335
336 /*
337 * Go through all the providers declared in this linker file and
338 * unregister any that aren't declared in another loaded file.
339 */
340 for (curr = begin; curr < end; curr++) {
341 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
342 if (strcmp(prov->name, (*curr)->name) != 0)
343 continue;
344
345 if (prov->sdt_refs == 1) {
346 if (dtrace_unregister(prov->id) != 0) {
347 *error = 1;
348 return;
349 }
350 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
351 free(prov->name, M_SDT);
352 free(prov, M_SDT);
353 } else
354 prov->sdt_refs--;
355 break;
356 }
357 }
358 }
359
360 static int
sdt_load_providers_cb(linker_file_t lf,void * arg __unused)361 sdt_load_providers_cb(linker_file_t lf, void *arg __unused)
362 {
363 sdt_kld_load_providers(lf);
364 return (0);
365 }
366
367 static int
sdt_load_probes_cb(linker_file_t lf,void * arg __unused)368 sdt_load_probes_cb(linker_file_t lf, void *arg __unused)
369 {
370 sdt_kld_load_probes(lf);
371 return (0);
372 }
373
374 static void
sdt_load(void)375 sdt_load(void)
376 {
377
378 TAILQ_INIT(&sdt_prov_list);
379
380 sdt_probe_func = dtrace_probe;
381
382 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL,
383 EVENTHANDLER_PRI_ANY);
384 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try,
385 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY);
386
387 /*
388 * Pick up probes from the kernel and already-loaded linker files.
389 * Define providers in a separate pass since a linker file may be using
390 * providers defined in a file that appears later in the list.
391 */
392 linker_file_foreach(sdt_load_providers_cb, NULL);
393 linker_file_foreach(sdt_load_probes_cb, NULL);
394 }
395
396 static int
sdt_unload(void)397 sdt_unload(void)
398 {
399 struct sdt_provider *prov, *tmp;
400 int ret;
401
402 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag);
403 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag);
404
405 sdt_probe_func = sdt_probe_stub;
406
407 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
408 ret = dtrace_unregister(prov->id);
409 if (ret != 0)
410 return (ret);
411 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
412 free(prov->name, M_SDT);
413 free(prov, M_SDT);
414 }
415
416 return (0);
417 }
418
419 static int
sdt_modevent(module_t mod __unused,int type,void * data __unused)420 sdt_modevent(module_t mod __unused, int type, void *data __unused)
421 {
422
423 switch (type) {
424 case MOD_LOAD:
425 case MOD_UNLOAD:
426 case MOD_SHUTDOWN:
427 return (0);
428 default:
429 return (EOPNOTSUPP);
430 }
431 }
432
433 SYSINIT(sdt_load, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_load, NULL);
434 SYSUNINIT(sdt_unload, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_unload, NULL);
435
436 DEV_MODULE(sdt, sdt_modevent, NULL);
437 MODULE_VERSION(sdt, 1);
438 MODULE_DEPEND(sdt, dtrace, 1, 1, 1);
439