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.
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.
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]
21 * Portions Copyright 2006-2008 John Birrell jb@freebsd.org
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.
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.
42 #include "opt_kdtrace.h"
44 #include <sys/cdefs.h>
45 #include <sys/param.h>
46 #include <sys/systm.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>
55 #include <sys/malloc.h>
56 #include <sys/module.h>
57 #include <sys/mutex.h>
58 #include <sys/queue.h>
61 #include <sys/dtrace.h>
62 #include <sys/dtrace_bsd.h>
65 static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *);
66 static void sdt_provide_probes(void *, dtrace_probedesc_t *);
67 static void sdt_destroy(void *, dtrace_id_t, void *);
68 static void sdt_enable(void *, dtrace_id_t, void *);
69 static void sdt_disable(void *, dtrace_id_t, void *);
71 static void sdt_load(void);
72 static int sdt_unload(void);
73 static void sdt_create_provider(struct sdt_provider *);
74 static void sdt_create_probe(struct sdt_probe *);
75 static void sdt_kld_load(void *, struct linker_file *);
76 static void sdt_kld_unload_try(void *, struct linker_file *, int *);
78 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers");
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 },
88 static dtrace_pops_t sdt_pops = {
101 static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
103 static eventhandler_tag sdt_kld_load_tag;
104 static eventhandler_tag sdt_kld_unload_try_tag;
107 sdt_create_provider(struct sdt_provider *prov)
109 struct sdt_provider *curr, *newprov;
111 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry)
112 if (strcmp(prov->name, curr->name) == 0) {
113 /* The provider has already been defined. */
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.
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;
127 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry);
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;
135 sdt_create_probe(struct sdt_probe *probe)
137 struct sdt_provider *prov;
138 char mod[DTRACE_MODNAMELEN];
139 char func[DTRACE_FUNCNAMELEN];
140 char name[DTRACE_NAMELEN];
145 if (probe->version != (int)sizeof(*probe)) {
146 printf("ignoring probe %p, version %u expected %u\n",
147 probe, probe->version, (int)sizeof(*probe));
151 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry)
152 if (strcmp(prov->name, probe->prov->name) == 0)
155 KASSERT(prov != NULL, ("probe defined without a provider"));
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)
163 strlcpy(mod, probe->mod, sizeof(mod));
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.
171 strlcpy(func, probe->func, sizeof(func));
173 strcpy(func, "none");
177 for (len = 0; len < (sizeof(name) - 1) && *from != '\0';
178 len++, from++, to++) {
179 if (from[0] == '_' && from[1] == '_') {
187 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE)
190 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe);
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.
199 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc)
204 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg)
206 struct sdt_probe *probe = parg;
209 probe->sdtp_lf->nenabled++;
213 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg)
215 struct sdt_probe *probe = parg;
217 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled"));
220 probe->sdtp_lf->nenabled--;
224 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc)
226 struct sdt_argtype *argtype;
227 struct sdt_probe *probe = parg;
229 if (desc->dtargd_ndx >= probe->n_args) {
230 desc->dtargd_ndx = DTRACE_ARGNONE;
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';
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));
252 sdt_destroy(void *arg, dtrace_id_t id, void *parg)
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.
264 sdt_kld_load(void *arg __unused, struct linker_file *lf)
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;
270 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
272 for (prov = begin; prov < end; prov++)
273 sdt_create_provider(*prov);
276 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end,
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);
285 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end,
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);
296 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
298 struct sdt_provider *prov, **curr, **begin, **end, *tmp;
301 /* We already have an error, so don't do anything. */
303 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
305 /* No DTrace providers are declared in this file. */
309 * Go through all the providers declared in this linker file and
310 * unregister any that aren't declared in another loaded file.
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)
317 if (prov->sdt_refs == 1) {
318 if (dtrace_unregister(prov->id) != 0) {
322 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
323 free(prov->name, M_SDT);
333 sdt_linker_file_cb(linker_file_t lf, void *arg __unused)
336 sdt_kld_load(NULL, lf);
345 TAILQ_INIT(&sdt_prov_list);
347 sdt_probe_func = dtrace_probe;
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);
354 /* Pick up probes from the kernel and already-loaded linker files. */
355 linker_file_foreach(sdt_linker_file_cb, NULL);
361 struct sdt_provider *prov, *tmp;
364 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag);
365 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag);
367 sdt_probe_func = sdt_probe_stub;
369 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
370 ret = dtrace_unregister(prov->id);
373 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
374 free(prov->name, M_SDT);
382 sdt_modevent(module_t mod __unused, int type, void *data __unused)
392 error = sdt_unload();
406 DEV_MODULE(sdt, sdt_modevent, NULL);
407 MODULE_VERSION(sdt, 1);
408 MODULE_DEPEND(sdt, dtrace, 1, 1, 1);