1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
|
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
* Portions Copyright 2006-2008 John Birrell jb@freebsd.org
*
* $FreeBSD$
*
*/
/*
* This file contains a reimplementation of the statically-defined tracing (SDT)
* framework for DTrace. Probes and SDT providers are defined using the macros
* in sys/sdt.h, which append all the needed structures to linker sets. When
* this module is loaded, it iterates over all of the loaded modules and
* registers probes and providers with the DTrace framework based on the
* contents of these linker sets.
*
* A list of SDT providers is maintained here since a provider may span multiple
* modules. When a kernel module is unloaded, a provider defined in that module
* is unregistered only if no other modules refer to it. The DTrace framework is
* responsible for destroying individual probes when a kernel module is
* unloaded; in particular, probes may not span multiple kernel modules.
*/
#include "opt_kdtrace.h"
#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/linker.h>
#include <sys/linker_set.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/queue.h>
#include <sys/sdt.h>
#include <sys/dtrace.h>
#include <sys/dtrace_bsd.h>
/* DTrace methods. */
static void sdt_getargdesc(void *, dtrace_id_t, void *, dtrace_argdesc_t *);
static void sdt_provide_probes(void *, dtrace_probedesc_t *);
static void sdt_destroy(void *, dtrace_id_t, void *);
static void sdt_enable(void *, dtrace_id_t, void *);
static void sdt_disable(void *, dtrace_id_t, void *);
static void sdt_load(void);
static int sdt_unload(void);
static void sdt_create_provider(struct sdt_provider *);
static void sdt_create_probe(struct sdt_probe *);
static void sdt_kld_load(void *, struct linker_file *);
static void sdt_kld_unload_try(void *, struct linker_file *, int *);
static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers");
static dtrace_pattr_t sdt_attr = {
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_ISA },
};
static dtrace_pops_t sdt_pops = {
sdt_provide_probes,
NULL,
sdt_enable,
sdt_disable,
NULL,
NULL,
sdt_getargdesc,
NULL,
NULL,
sdt_destroy,
};
static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
static eventhandler_tag sdt_kld_load_tag;
static eventhandler_tag sdt_kld_unload_try_tag;
static void
sdt_create_provider(struct sdt_provider *prov)
{
struct sdt_provider *curr, *newprov;
TAILQ_FOREACH(curr, &sdt_prov_list, prov_entry)
if (strcmp(prov->name, curr->name) == 0) {
/* The provider has already been defined. */
curr->sdt_refs++;
return;
}
/*
* Make a copy of prov so that we don't lose fields if its module is
* unloaded but the provider isn't destroyed. This could happen with
* a provider that spans multiple modules.
*/
newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO);
newprov->name = strdup(prov->name, M_SDT);
prov->sdt_refs = newprov->sdt_refs = 1;
TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry);
(void)dtrace_register(newprov->name, &sdt_attr, DTRACE_PRIV_USER, NULL,
&sdt_pops, NULL, (dtrace_provider_id_t *)&newprov->id);
prov->id = newprov->id;
}
static void
sdt_create_probe(struct sdt_probe *probe)
{
struct sdt_provider *prov;
char mod[DTRACE_MODNAMELEN];
char func[DTRACE_FUNCNAMELEN];
char name[DTRACE_NAMELEN];
const char *from;
char *to;
size_t len;
if (probe->version != (int)sizeof(*probe)) {
printf("ignoring probe %p, version %u expected %u\n",
probe, probe->version, (int)sizeof(*probe));
return;
}
TAILQ_FOREACH(prov, &sdt_prov_list, prov_entry)
if (strcmp(prov->name, probe->prov->name) == 0)
break;
KASSERT(prov != NULL, ("probe defined without a provider"));
/* If no module name was specified, use the module filename. */
if (*probe->mod == 0) {
len = strlcpy(mod, probe->sdtp_lf->filename, sizeof(mod));
if (len > 3 && strcmp(mod + len - 3, ".ko") == 0)
mod[len - 3] = '\0';
} else
strlcpy(mod, probe->mod, sizeof(mod));
/*
* Unfortunately this is necessary because the Solaris DTrace
* code mixes consts and non-consts with casts to override
* the incompatibilies. On FreeBSD, we use strict warnings
* in the C compiler, so we have to respect const vs non-const.
*/
strlcpy(func, probe->func, sizeof(func));
from = probe->name;
to = name;
for (len = 0; len < (sizeof(name) - 1) && *from != '\0';
len++, from++, to++) {
if (from[0] == '_' && from[1] == '_') {
*to = '-';
from++;
} else
*to = *from;
}
*to = '\0';
if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE)
return;
(void)dtrace_probe_create(prov->id, mod, func, name, 1, probe);
}
/*
* Probes are created through the SDT module load/unload hook, so this function
* has nothing to do. It only exists because the DTrace provider framework
* requires one of provide_probes and provide_module to be defined.
*/
static void
sdt_provide_probes(void *arg, dtrace_probedesc_t *desc)
{
}
static void
sdt_enable(void *arg __unused, dtrace_id_t id, void *parg)
{
struct sdt_probe *probe = parg;
probe->id = id;
probe->sdtp_lf->nenabled++;
}
static void
sdt_disable(void *arg __unused, dtrace_id_t id, void *parg)
{
struct sdt_probe *probe = parg;
KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled"));
probe->id = 0;
probe->sdtp_lf->nenabled--;
}
static void
sdt_getargdesc(void *arg, dtrace_id_t id, void *parg, dtrace_argdesc_t *desc)
{
struct sdt_argtype *argtype;
struct sdt_probe *probe = parg;
if (desc->dtargd_ndx >= probe->n_args) {
desc->dtargd_ndx = DTRACE_ARGNONE;
return;
}
TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) {
if (desc->dtargd_ndx == argtype->ndx) {
desc->dtargd_mapping = desc->dtargd_ndx;
if (argtype->type == NULL) {
desc->dtargd_native[0] = '\0';
desc->dtargd_xlate[0] = '\0';
continue;
}
strlcpy(desc->dtargd_native, argtype->type,
sizeof(desc->dtargd_native));
if (argtype->xtype != NULL)
strlcpy(desc->dtargd_xlate, argtype->xtype,
sizeof(desc->dtargd_xlate));
}
}
}
static void
sdt_destroy(void *arg, dtrace_id_t id, void *parg)
{
}
/*
* Called from the kernel linker when a module is loaded, before
* dtrace_module_loaded() is called. This is done so that it's possible to
* register new providers when modules are loaded. The DTrace framework
* explicitly disallows calling into the framework from the provide_module
* provider method, so we cannot do this there.
*/
static void
sdt_kld_load(void *arg __unused, struct linker_file *lf)
{
struct sdt_provider **prov, **begin, **end;
struct sdt_probe **probe, **p_begin, **p_end;
struct sdt_argtype **argtype, **a_begin, **a_end;
if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
NULL) == 0) {
for (prov = begin; prov < end; prov++)
sdt_create_provider(*prov);
}
if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end,
NULL) == 0) {
for (probe = p_begin; probe < p_end; probe++) {
(*probe)->sdtp_lf = lf;
sdt_create_probe(*probe);
TAILQ_INIT(&(*probe)->argtype_list);
}
}
if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end,
NULL) == 0) {
for (argtype = a_begin; argtype < a_end; argtype++) {
(*argtype)->probe->n_args++;
TAILQ_INSERT_TAIL(&(*argtype)->probe->argtype_list,
*argtype, argtype_entry);
}
}
}
static void
sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
{
struct sdt_provider *prov, **curr, **begin, **end, *tmp;
if (*error != 0)
/* We already have an error, so don't do anything. */
return;
else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
NULL))
/* No DTrace providers are declared in this file. */
return;
/*
* Go through all the providers declared in this linker file and
* unregister any that aren't declared in another loaded file.
*/
for (curr = begin; curr < end; curr++) {
TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
if (strcmp(prov->name, (*curr)->name) != 0)
continue;
if (prov->sdt_refs == 1) {
if (dtrace_unregister(prov->id) != 0) {
*error = 1;
return;
}
TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
free(prov->name, M_SDT);
free(prov, M_SDT);
} else
prov->sdt_refs--;
break;
}
}
}
static int
sdt_linker_file_cb(linker_file_t lf, void *arg __unused)
{
sdt_kld_load(NULL, lf);
return (0);
}
static void
sdt_load()
{
TAILQ_INIT(&sdt_prov_list);
sdt_probe_func = dtrace_probe;
sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL,
EVENTHANDLER_PRI_ANY);
sdt_kld_unload_try_tag = EVENTHANDLER_REGISTER(kld_unload_try,
sdt_kld_unload_try, NULL, EVENTHANDLER_PRI_ANY);
/* Pick up probes from the kernel and already-loaded linker files. */
linker_file_foreach(sdt_linker_file_cb, NULL);
}
static int
sdt_unload()
{
struct sdt_provider *prov, *tmp;
int ret;
EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag);
EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag);
sdt_probe_func = sdt_probe_stub;
TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
ret = dtrace_unregister(prov->id);
if (ret != 0)
return (ret);
TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
free(prov->name, M_SDT);
free(prov, M_SDT);
}
return (0);
}
static int
sdt_modevent(module_t mod __unused, int type, void *data __unused)
{
int error = 0;
switch (type) {
case MOD_LOAD:
sdt_load();
break;
case MOD_UNLOAD:
error = sdt_unload();
break;
case MOD_SHUTDOWN:
break;
default:
error = EOPNOTSUPP;
break;
}
return (error);
}
DEV_MODULE(sdt, sdt_modevent, NULL);
MODULE_VERSION(sdt, 1);
MODULE_DEPEND(sdt, dtrace, 1, 1, 1);
|