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 [email protected]
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/cdefs.h>
41 #include <sys/param.h>
42 #include <sys/systm.h>
43
44 #include <sys/conf.h>
45 #include <sys/endian.h>
46 #include <sys/eventhandler.h>
47 #include <sys/kernel.h>
48 #include <sys/limits.h>
49 #include <sys/linker.h>
50 #include <sys/linker_set.h>
51 #include <sys/lock.h>
52 #include <sys/lockstat.h>
53 #include <sys/malloc.h>
54 #include <sys/module.h>
55 #include <sys/mutex.h>
56 #include <sys/queue.h>
57 #include <sys/sdt.h>
58
59 #include <sys/dtrace.h>
60 #include <sys/dtrace_bsd.h>
61
62 /* DTrace methods. */
63 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *);
64 static void sdt_provide_probes(void *, dtrace_probedesc_t *);
65 static void sdt_destroy(void *, dtrace_id_t, void *);
66 static void sdt_enable(void *, dtrace_id_t, void *);
67 static void sdt_disable(void *, dtrace_id_t, void *);
68
69 static void sdt_load(void);
70 static int sdt_unload(void);
71 static void sdt_create_provider(struct sdt_provider *);
72 static void sdt_create_probe(struct sdt_probe *);
73 static void sdt_kld_load(void *, struct linker_file *);
74 static void sdt_kld_unload_try(void *, struct linker_file *, int *);
75
76 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers");
77
78 static int sdt_probes_enabled_count;
79 static int lockstat_enabled_count;
80
81 static dtrace_pattr_t sdt_attr = {
82 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
83 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
84 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
85 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
86 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
87 };
88
89 static dtrace_pops_t sdt_pops = {
90 .dtps_provide = sdt_provide_probes,
91 .dtps_provide_module = NULL,
92 .dtps_enable = sdt_enable,
93 .dtps_disable = sdt_disable,
94 .dtps_suspend = NULL,
95 .dtps_resume = NULL,
96 .dtps_getargdesc = sdt_getargdesc,
97 .dtps_getargval = NULL,
98 .dtps_usermode = NULL,
99 .dtps_destroy = sdt_destroy,
100 };
101
102 static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
103
104 static eventhandler_tag sdt_kld_load_tag;
105 static eventhandler_tag sdt_kld_unload_try_tag;
106
107 static void
sdt_create_provider(struct sdt_provider * prov)108 sdt_create_provider(struct sdt_provider *prov)
109 {
110 struct sdt_provider *curr, *newprov;
111
112 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry)
113 if (strcmp(prov->name, curr->name) == 0) {
114 /* The provider has already been defined. */
115 curr->sdt_refs++;
116 return;
117 }
118
119 /*
120 * Make a copy of prov so that we don't lose fields if its module is
121 * unloaded but the provider isn't destroyed. This could happen with
122 * a provider that spans multiple modules.
123 */
124 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO);
125 newprov->name = strdup(prov->name, M_SDT);
126 prov->sdt_refs = newprov->sdt_refs = 1;
127
128 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry);
129
130 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL,
131 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id);
132 prov->id = newprov->id;
133 }
134
135 static void
sdt_create_probe(struct sdt_probe * probe)136 sdt_create_probe(struct sdt_probe *probe)
137 {
138 struct sdt_provider *prov;
139 char mod[DTRACE_MODNAMELEN];
140 char func[DTRACE_FUNCNAMELEN];
141 char name[DTRACE_NAMELEN];
142 const char *from;
143 char *to;
144 size_t len;
145
146 if (probe->version != (int)sizeof(*probe)) {
147 printf("ignoring probe %p, version %u expected %u\n",
148 probe, probe->version, (int)sizeof(*probe));
149 return;
150 }
151
152 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry)
153 if (strcmp(prov->name, probe->prov->name) == 0)
154 break;
155
156 KASSERT(prov != NULL, ("probe defined without a provider"));
157
158 /* If no module name was specified, use the module filename. */
159 if (*probe->mod == 0) {
160 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod));
161 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0)
162 mod[len - 3] = '\0';
163 } else
164 strlcpy(mod, probe->mod, sizeof(mod));
165
166 /*
167 * Unfortunately this is necessary because the Solaris DTrace
168 * code mixes consts and non-consts with casts to override
169 * the incompatibilies. On FreeBSD, we use strict warnings
170 * in the C compiler, so we have to respect const vs non-const.
171 */
172 strlcpy(func, probe->func, sizeof(func));
173 if (func[0] == '\0')
174 strcpy(func, "none");
175
176 from = probe->name;
177 to = name;
178 for (len = 0; len < (sizeof(name) - 1) && *from != '\0';
179 len++, from++, to++) {
180 if (from[0] == '_' && from[1] == '_') {
181 *to = '-';
182 from++;
183 } else
184 *to = *from;
185 }
186 *to = '\0';
187
188 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE)
189 return;
190
191 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe);
192 }
193
194 /*
195 * Probes are created through the SDT module load/unload hook, so this function
196 * has nothing to do. It only exists because the DTrace provider framework
197 * requires one of provide_probes and provide_module to be defined.
198 */
199 static void
sdt_provide_probes(void * arg,dtrace_probedesc_t * desc)200 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc)
201 {
202 }
203
204 static void
sdt_enable(void * arg __unused,dtrace_id_t id,void * parg)205 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg)
206 {
207 struct sdt_probe *probe = parg;
208
209 probe->id = id;
210 probe->sdtp_lf->nenabled++;
211 if (strcmp(probe->prov->name, "lockstat") == 0) {
212 lockstat_enabled_count++;
213 if (lockstat_enabled_count == 1)
214 lockstat_enabled = true;
215 }
216 sdt_probes_enabled_count++;
217 if (sdt_probes_enabled_count == 1)
218 sdt_probes_enabled = true;
219 }
220
221 static void
sdt_disable(void * arg __unused,dtrace_id_t id,void * parg)222 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg)
223 {
224 struct sdt_probe *probe = parg;
225
226 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled"));
227
228 sdt_probes_enabled_count--;
229 if (sdt_probes_enabled_count == 0)
230 sdt_probes_enabled = false;
231 if (strcmp(probe->prov->name, "lockstat") == 0) {
232 lockstat_enabled_count--;
233 if (lockstat_enabled_count == 0)
234 lockstat_enabled = false;
235 }
236 probe->id = 0;
237 probe->sdtp_lf->nenabled--;
238 }
239
240 static void
sdt_getargdesc(void * arg,dtrace_id_t id,void * parg,dtrace_argdesc_t * desc)241 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc)
242 {
243 struct sdt_argtype *argtype;
244 struct sdt_probe *probe = parg;
245
246 if (desc->dtargd_ndx >= probe->n_args) {
247 desc->dtargd_ndx = DTRACE_ARGNONE;
248 return;
249 }
250
251 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) {
252 if (desc->dtargd_ndx == argtype->ndx) {
253 desc->dtargd_mapping = desc->dtargd_ndx;
254 if (argtype->type == NULL) {
255 desc->dtargd_native[0] = '\0';
256 desc->dtargd_xlate[0] = '\0';
257 continue;
258 }
259 strlcpy(desc->dtargd_native, argtype->type,
260 sizeof(desc->dtargd_native));
261 if (argtype->xtype != NULL)
262 strlcpy(desc->dtargd_xlate, argtype->xtype,
263 sizeof(desc->dtargd_xlate));
264 }
265 }
266 }
267
268 static void
sdt_destroy(void * arg,dtrace_id_t id,void * parg)269 sdt_destroy(void *arg, dtrace_id_t id, void *parg)
270 {
271 }
272
273 static void
sdt_kld_load_providers(struct linker_file * lf)274 sdt_kld_load_providers(struct linker_file *lf)
275 {
276 struct sdt_provider **prov, **begin, **end;
277
278 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
279 NULL) == 0) {
280 for (prov = begin; prov < end; prov++)
281 sdt_create_provider(*prov);
282 }
283 }
284
285 static void
sdt_kld_load_probes(struct linker_file * lf)286 sdt_kld_load_probes(struct linker_file *lf)
287 {
288 struct sdt_probe **probe, **p_begin, **p_end;
289 struct sdt_argtype **argtype, **a_begin, **a_end;
290
291 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end,
292 NULL) == 0) {
293 for (probe = p_begin; probe < p_end; probe++) {
294 (*probe)->sdtp_lf = lf;
295 sdt_create_probe(*probe);
296 TAILQ_INIT(&(*probe)->argtype_list);
297 }
298 }
299
300 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end,
301 NULL) == 0) {
302 for (argtype = a_begin; argtype < a_end; argtype++) {
303 (*argtype)->probe->n_args++;
304 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list,
305 *argtype, argtype_entry);
306 }
307 }
308 }
309
310 /*
311 * Called from the kernel linker when a module is loaded, before
312 * dtrace_module_loaded() is called. This is done so that it's possible to
313 * register new providers when modules are loaded. The DTrace framework
314 * explicitly disallows calling into the framework from the provide_module
315 * provider method, so we cannot do this there.
316 */
317 static void
sdt_kld_load(void * arg __unused,struct linker_file * lf)318 sdt_kld_load(void *arg __unused, struct linker_file *lf)
319 {
320 sdt_kld_load_providers(lf);
321 sdt_kld_load_probes(lf);
322 }
323
324 static void
sdt_kld_unload_try(void * arg __unused,struct linker_file * lf,int * error)325 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
326 {
327 struct sdt_provider *prov, **curr, **begin, **end, *tmp;
328
329 if (*error != 0)
330 /* We already have an error, so don't do anything. */
331 return;
332 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
333 NULL))
334 /* No DTrace providers are declared in this file. */
335 return;
336
337 /*
338 * Go through all the providers declared in this linker file and
339 * unregister any that aren't declared in another loaded file.
340 */
341 for (curr = begin; curr < end; curr++) {
342 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
343 if (strcmp(prov->name, (*curr)->name) != 0)
344 continue;
345
346 if (prov->sdt_refs == 1) {
347 if (dtrace_unregister(prov->id) != 0) {
348 *error = 1;
349 return;
350 }
351 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
352 free(prov->name, M_SDT);
353 free(prov, M_SDT);
354 } else
355 prov->sdt_refs--;
356 break;
357 }
358 }
359 }
360
361 static int
sdt_load_providers_cb(linker_file_t lf,void * arg __unused)362 sdt_load_providers_cb(linker_file_t lf, void *arg __unused)
363 {
364 sdt_kld_load_providers(lf);
365 return (0);
366 }
367
368 static int
sdt_load_probes_cb(linker_file_t lf,void * arg __unused)369 sdt_load_probes_cb(linker_file_t lf, void *arg __unused)
370 {
371 sdt_kld_load_probes(lf);
372 return (0);
373 }
374
375 static void
sdt_load(void)376 sdt_load(void)
377 {
378
379 TAILQ_INIT(&sdt_prov_list);
380
381 sdt_probe_func = dtrace_probe;
382
383 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL,
384 EVENTHANDLER_PRI_ANY);
385 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try,
386 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY);
387
388 /*
389 * Pick up probes from the kernel and already-loaded linker files.
390 * Define providers in a separate pass since a linker file may be using
391 * providers defined in a file that appears later in the list.
392 */
393 linker_file_foreach(sdt_load_providers_cb, NULL);
394 linker_file_foreach(sdt_load_probes_cb, NULL);
395 }
396
397 static int
sdt_unload(void)398 sdt_unload(void)
399 {
400 struct sdt_provider *prov, *tmp;
401 int ret;
402
403 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag);
404 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag);
405
406 sdt_probe_func = sdt_probe_stub;
407
408 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
409 ret = dtrace_unregister(prov->id);
410 if (ret != 0)
411 return (ret);
412 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
413 free(prov->name, M_SDT);
414 free(prov, M_SDT);
415 }
416
417 return (0);
418 }
419
420 static int
sdt_modevent(module_t mod __unused,int type,void * data __unused)421 sdt_modevent(module_t mod __unused, int type, void *data __unused)
422 {
423
424 switch (type) {
425 case MOD_LOAD:
426 case MOD_UNLOAD:
427 case MOD_SHUTDOWN:
428 return (0);
429 default:
430 return (EOPNOTSUPP);
431 }
432 }
433
434 SYSINIT(sdt_load, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_load, NULL);
435 SYSUNINIT(sdt_unload, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_unload, NULL);
436
437 DEV_MODULE(sdt, sdt_modevent, NULL);
438 MODULE_VERSION(sdt, 1);
439 MODULE_DEPEND(sdt, dtrace, 1, 1, 1);
440