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 <sys/cdefs.h>
43 #include <sys/param.h>
44 #include <sys/systm.h>
47 #include <sys/eventhandler.h>
48 #include <sys/kernel.h>
49 #include <sys/limits.h>
50 #include <sys/linker.h>
51 #include <sys/linker_set.h>
53 #include <sys/malloc.h>
54 #include <sys/module.h>
55 #include <sys/mutex.h>
56 #include <sys/queue.h>
59 #include <sys/dtrace.h>
60 #include <sys/dtrace_bsd.h>
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 *);
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 *);
76 static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers");
78 static dtrace_pattr_t sdt_attr = {
79 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
80 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
81 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
82 { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
83 { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
86 static dtrace_pops_t sdt_pops = {
99 static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
101 eventhandler_tag sdt_kld_load_tag;
102 eventhandler_tag sdt_kld_unload_try_tag;
105 sdt_create_provider(struct sdt_provider *prov)
107 struct sdt_provider *curr, *newprov;
109 TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry)
110 if (strcmp(prov->name, curr->name) == 0) {
111 /* The provider has already been defined. */
117 * Make a copy of prov so that we don't lose fields if its module is
118 * unloaded but the provider isn't destroyed. This could happen with
119 * a provider that spans multiple modules.
121 newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO);
122 newprov->name = strdup(prov->name, M_SDT);
123 prov->sdt_refs = newprov->sdt_refs = 1;
125 TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry);
127 (void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL,
128 &sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id);
129 prov->id = newprov->id;
133 sdt_create_probe(struct sdt_probe *probe)
135 struct sdt_provider *prov;
136 char mod[DTRACE_MODNAMELEN];
137 char func[DTRACE_FUNCNAMELEN];
138 char name[DTRACE_NAMELEN];
143 TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry)
144 if (strcmp(prov->name, probe->prov->name) == 0)
147 KASSERT(prov != NULL, ("probe defined without a provider"));
149 /* If no module name was specified, use the module filename. */
150 if (*probe->mod == 0) {
151 len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod));
152 if (len > 3 && strcmp(mod + len - 3, ".ko") == 0)
155 strlcpy(mod, probe->mod, sizeof(mod));
158 * Unfortunately this is necessary because the Solaris DTrace
159 * code mixes consts and non-consts with casts to override
160 * the incompatibilies. On FreeBSD, we use strict warnings
161 * in the C compiler, so we have to respect const vs non-const.
163 strlcpy(func, probe->func, sizeof(func));
167 for (len = 0; len < (sizeof(name) - 1) && *from != '\0';
168 len++, from++, to++) {
169 if (from[0] == '_' && from[1] == '_') {
177 if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE)
180 (void)dtrace_probe_create(prov->id, mod, func, name, 1, probe);
184 * Probes are created through the SDT module load/unload hook, so this function
185 * has nothing to do. It only exists because the DTrace provider framework
186 * requires one of provide_probes and provide_module to be defined.
189 sdt_provide_probes(void *arg, dtrace_probedesc_t *desc)
194 sdt_enable(void *arg __unused, dtrace_id_t id, void *parg)
196 struct sdt_probe *probe = parg;
199 probe->sdtp_lf->nenabled++;
203 sdt_disable(void *arg __unused, dtrace_id_t id, void *parg)
205 struct sdt_probe *probe = parg;
207 KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled"));
210 probe->sdtp_lf->nenabled--;
214 sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc)
216 struct sdt_argtype *argtype;
217 struct sdt_probe *probe = parg;
219 if (desc->dtargd_ndx >= probe->n_args) {
220 desc->dtargd_ndx = DTRACE_ARGNONE;
224 TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) {
225 if (desc->dtargd_ndx == argtype->ndx) {
226 desc->dtargd_mapping = desc->dtargd_ndx;
227 if (argtype->type == NULL) {
228 desc->dtargd_native[0] = '\0';
229 desc->dtargd_xlate[0] = '\0';
232 strlcpy(desc->dtargd_native, argtype->type,
233 sizeof(desc->dtargd_native));
234 if (argtype->xtype != NULL)
235 strlcpy(desc->dtargd_xlate, argtype->xtype,
236 sizeof(desc->dtargd_xlate));
242 sdt_destroy(void *arg, dtrace_id_t id, void *parg)
247 * Called from the kernel linker when a module is loaded, before
248 * dtrace_module_loaded() is called. This is done so that it's possible to
249 * register new providers when modules are loaded. The DTrace framework
250 * explicitly disallows calling into the framework from the provide_module
251 * provider method, so we cannot do this there.
254 sdt_kld_load(void *arg __unused, struct linker_file *lf)
256 struct sdt_provider **prov, **begin, **end;
257 struct sdt_probe **probe, **p_begin, **p_end;
258 struct sdt_argtype **argtype, **a_begin, **a_end;
260 if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
262 for (prov = begin; prov < end; prov++)
263 sdt_create_provider(*prov);
266 if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end,
268 for (probe = p_begin; probe < p_end; probe++) {
269 (*probe)->sdtp_lf = lf;
270 sdt_create_probe(*probe);
271 TAILQ_INIT(&(*probe)->argtype_list);
275 if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end,
277 for (argtype = a_begin; argtype < a_end; argtype++) {
278 (*argtype)->probe->n_args++;
279 TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list,
280 *argtype, argtype_entry);
286 sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
288 struct sdt_provider *prov, **curr, **begin, **end, *tmp;
291 /* We already have an error, so don't do anything. */
293 else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
295 /* No DTrace providers are declared in this file. */
299 * Go through all the providers declared in this linker file and
300 * unregister any that aren't declared in another loaded file.
302 for (curr = begin; curr < end; curr++) {
303 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
304 if (strcmp(prov->name, (*curr)->name) != 0)
307 if (prov->sdt_refs == 1) {
308 if (dtrace_unregister(prov->id) != 0) {
312 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
313 free(prov->name, M_SDT);
323 sdt_linker_file_cb(linker_file_t lf, void *arg __unused)
326 sdt_kld_load(NULL, lf);
335 TAILQ_INIT(&sdt_prov_list);
337 sdt_probe_func = dtrace_probe;
339 sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL,
340 EVENTHANDLER_PRI_ANY);
341 sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try,
342 sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY);
344 /* Pick up probes from the kernel and already-loaded linker files. */
345 linker_file_foreach(sdt_linker_file_cb, NULL);
351 struct sdt_provider *prov, *tmp;
354 EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag);
355 EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag);
357 sdt_probe_func = sdt_probe_stub;
359 TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
360 ret = dtrace_unregister(prov->id);
363 TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
364 free(prov->name, M_SDT);
372 sdt_modevent(module_t mod __unused, int type, void *data __unused)
382 error = sdt_unload();
396 DEV_MODULE(sdt, sdt_modevent, NULL);
397 MODULE_VERSION(sdt, 1);
398 MODULE_DEPEND(sdt, dtrace, 1, 1, 1);
399 MODULE_DEPEND(sdt, opensolaris, 1, 1, 1);