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 /*
22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /*
27 * Copyright (c) 2012, Joyent, Inc. All rights reserved.
28 */
29
30 #include <sys/modctl.h>
31 #include <sys/sunddi.h>
32 #include <sys/dtrace.h>
33 #include <sys/kobj.h>
34 #include <sys/stat.h>
35 #include <sys/conf.h>
36 #include <vm/seg_kmem.h>
37 #include <sys/stack.h>
38 #include <sys/frame.h>
39 #include <sys/dtrace_impl.h>
40 #include <sys/cmn_err.h>
41 #include <sys/sysmacros.h>
42 #include <sys/privregs.h>
43 #include <sys/sdt_impl.h>
44
45 #define SDT_PATCHVAL 0xf0
46 #define SDT_ADDR2NDX(addr) ((((uintptr_t)(addr)) >> 4) & sdt_probetab_mask)
47 #define SDT_PROBETAB_SIZE 0x1000 /* 4k entries -- 16K total */
48
49 static dev_info_t *sdt_devi;
50 static int sdt_verbose = 0;
51 static sdt_probe_t **sdt_probetab;
52 static int sdt_probetab_size;
53 static int sdt_probetab_mask;
54
55 /*ARGSUSED*/
56 static int
57 sdt_invop(uintptr_t addr, uintptr_t *stack, uintptr_t eax)
58 {
59 uintptr_t stack0, stack1, stack2, stack3, stack4;
60 int i = 0;
61 sdt_probe_t *sdt = sdt_probetab[SDT_ADDR2NDX(addr)];
62
63 #ifdef __amd64
64 /*
65 * On amd64, stack[0] contains the dereferenced stack pointer,
66 * stack[1] contains savfp, stack[2] contains savpc. We want
67 * to step over these entries.
68 */
69 i += 3;
70 #endif
71
72 for (; sdt != NULL; sdt = sdt->sdp_hashnext) {
73 if ((uintptr_t)sdt->sdp_patchpoint == addr) {
74 /*
75 * When accessing the arguments on the stack, we must
76 * protect against accessing beyond the stack. We can
77 * safely set NOFAULT here -- we know that interrupts
78 * are already disabled.
79 */
80 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
81 stack0 = stack[i++];
82 stack1 = stack[i++];
83 stack2 = stack[i++];
84 stack3 = stack[i++];
85 stack4 = stack[i++];
86 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT |
87 CPU_DTRACE_BADADDR);
88
89 dtrace_probe(sdt->sdp_id, stack0, stack1,
90 stack2, stack3, stack4);
91
92 return (DTRACE_INVOP_NOP);
93 }
94 }
95
96 return (0);
97 }
98
99 /*ARGSUSED*/
100 static void
101 sdt_provide_module(void *arg, struct modctl *ctl)
102 {
103 struct module *mp = ctl->mod_mp;
104 char *modname = ctl->mod_modname;
105 sdt_probedesc_t *sdpd;
106 sdt_probe_t *sdp, *old;
107 sdt_provider_t *prov;
108 int len;
109
110 /*
111 * One for all, and all for one: if we haven't yet registered all of
112 * our providers, we'll refuse to provide anything.
113 */
114 for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
115 if (prov->sdtp_id == DTRACE_PROVNONE)
116 return;
117 }
118
119 if (mp->sdt_nprobes != 0 || (sdpd = mp->sdt_probes) == NULL)
120 return;
121
122 for (sdpd = mp->sdt_probes; sdpd != NULL; sdpd = sdpd->sdpd_next) {
123 char *name = sdpd->sdpd_name, *func, *nname;
124 int i, j;
125 sdt_provider_t *prov;
126 ulong_t offs;
127 dtrace_id_t id;
128
129 for (prov = sdt_providers; prov->sdtp_prefix != NULL; prov++) {
130 char *prefix = prov->sdtp_prefix;
131
132 if (strncmp(name, prefix, strlen(prefix)) == 0) {
133 name += strlen(prefix);
134 break;
135 }
136 }
137
138 nname = kmem_alloc(len = strlen(name) + 1, KM_SLEEP);
139
140 for (i = 0, j = 0; name[j] != '\0'; i++) {
141 if (name[j] == '_' && name[j + 1] == '_') {
142 nname[i] = '-';
143 j += 2;
144 } else {
145 nname[i] = name[j++];
146 }
147 }
148
149 nname[i] = '\0';
150
151 sdp = kmem_zalloc(sizeof (sdt_probe_t), KM_SLEEP);
152 sdp->sdp_loadcnt = ctl->mod_loadcnt;
153 sdp->sdp_ctl = ctl;
154 sdp->sdp_name = nname;
155 sdp->sdp_namelen = len;
156 sdp->sdp_provider = prov;
157
158 func = kobj_searchsym(mp, sdpd->sdpd_offset, &offs);
159
160 if (func == NULL)
161 func = "<unknown>";
162
163 /*
164 * We have our provider. Now create the probe.
165 */
166 if ((id = dtrace_probe_lookup(prov->sdtp_id, modname,
167 func, nname)) != DTRACE_IDNONE) {
168 old = dtrace_probe_arg(prov->sdtp_id, id);
169 ASSERT(old != NULL);
170
171 sdp->sdp_next = old->sdp_next;
172 sdp->sdp_id = id;
173 old->sdp_next = sdp;
174 } else {
175 sdp->sdp_id = dtrace_probe_create(prov->sdtp_id,
176 modname, func, nname, 3, sdp);
177
178 mp->sdt_nprobes++;
179 }
180
181 sdp->sdp_hashnext =
182 sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)];
183 sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)] = sdp;
184
185 sdp->sdp_patchval = SDT_PATCHVAL;
186 sdp->sdp_patchpoint = (uint8_t *)sdpd->sdpd_offset;
187 sdp->sdp_savedval = *sdp->sdp_patchpoint;
188 }
189 }
190
191 /*ARGSUSED*/
192 static void
193 sdt_destroy(void *arg, dtrace_id_t id, void *parg)
194 {
195 sdt_probe_t *sdp = parg, *old, *last, *hash;
196 struct modctl *ctl = sdp->sdp_ctl;
197 int ndx;
198
199 if (ctl != NULL && ctl->mod_loadcnt == sdp->sdp_loadcnt) {
200 if ((ctl->mod_loadcnt == sdp->sdp_loadcnt &&
201 ctl->mod_loaded)) {
202 ((struct module *)(ctl->mod_mp))->sdt_nprobes--;
203 }
204 }
205
206 while (sdp != NULL) {
207 old = sdp;
208
209 /*
210 * Now we need to remove this probe from the sdt_probetab.
211 */
212 ndx = SDT_ADDR2NDX(sdp->sdp_patchpoint);
213 last = NULL;
214 hash = sdt_probetab[ndx];
215
216 while (hash != sdp) {
217 ASSERT(hash != NULL);
218 last = hash;
219 hash = hash->sdp_hashnext;
220 }
221
222 if (last != NULL) {
223 last->sdp_hashnext = sdp->sdp_hashnext;
224 } else {
225 sdt_probetab[ndx] = sdp->sdp_hashnext;
226 }
227
228 kmem_free(sdp->sdp_name, sdp->sdp_namelen);
229 sdp = sdp->sdp_next;
230 kmem_free(old, sizeof (sdt_probe_t));
231 }
232 }
233
234 /*ARGSUSED*/
235 static int
236 sdt_enable(void *arg, dtrace_id_t id, void *parg)
237 {
238 sdt_probe_t *sdp = parg;
239 struct modctl *ctl = sdp->sdp_ctl;
240
241 ctl->mod_nenabled++;
242
243 /*
244 * If this module has disappeared since we discovered its probes,
245 * refuse to enable it.
246 */
247 if (!ctl->mod_loaded) {
248 if (sdt_verbose) {
249 cmn_err(CE_NOTE, "sdt is failing for probe %s "
250 "(module %s unloaded)",
251 sdp->sdp_name, ctl->mod_modname);
252 }
253 goto err;
254 }
255
256 /*
257 * Now check that our modctl has the expected load count. If it
258 * doesn't, this module must have been unloaded and reloaded -- and
259 * we're not going to touch it.
260 */
261 if (ctl->mod_loadcnt != sdp->sdp_loadcnt) {
262 if (sdt_verbose) {
263 cmn_err(CE_NOTE, "sdt is failing for probe %s "
264 "(module %s reloaded)",
265 sdp->sdp_name, ctl->mod_modname);
266 }
267 goto err;
268 }
269
270 while (sdp != NULL) {
271 *sdp->sdp_patchpoint = sdp->sdp_patchval;
272 sdp = sdp->sdp_next;
273 }
274 err:
275 return (0);
276 }
277
278 /*ARGSUSED*/
279 static void
280 sdt_disable(void *arg, dtrace_id_t id, void *parg)
281 {
282 sdt_probe_t *sdp = parg;
283 struct modctl *ctl = sdp->sdp_ctl;
284
285 ctl->mod_nenabled--;
286
287 if (!ctl->mod_loaded || ctl->mod_loadcnt != sdp->sdp_loadcnt)
288 goto err;
289
290 while (sdp != NULL) {
291 *sdp->sdp_patchpoint = sdp->sdp_savedval;
292 sdp = sdp->sdp_next;
293 }
294
295 err:
296 ;
297 }
298
299 /*ARGSUSED*/
300 uint64_t
301 sdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno, int aframes)
302 {
303 uintptr_t val;
304 struct frame *fp = (struct frame *)dtrace_getfp();
305 uintptr_t *stack;
306 int i;
307 #if defined(__amd64)
308 /*
309 * A total of 6 arguments are passed via registers; any argument with
310 * index of 5 or lower is therefore in a register.
311 */
312 int inreg = 5;
313 #endif
314
315 for (i = 1; i <= aframes; i++) {
316 fp = (struct frame *)(fp->fr_savfp);
317
318 if (fp->fr_savpc == (pc_t)dtrace_invop_callsite) {
319 #if !defined(__amd64)
320 /*
321 * If we pass through the invalid op handler, we will
322 * use the pointer that it passed to the stack as the
323 * second argument to dtrace_invop() as the pointer to
324 * the stack.
325 */
326 stack = ((uintptr_t **)&fp[1])[1];
327 #else
328 /*
329 * In the case of amd64, we will use the pointer to the
330 * regs structure that was pushed when we took the
331 * trap. To get this structure, we must increment
332 * beyond the frame structure. If the argument that
333 * we're seeking is passed on the stack, we'll pull
334 * the true stack pointer out of the saved registers
335 * and decrement our argument by the number of
336 * arguments passed in registers; if the argument
337 * we're seeking is passed in regsiters, we can just
338 * load it directly.
339 */
340 struct regs *rp = (struct regs *)((uintptr_t)&fp[1] +
341 sizeof (uintptr_t));
342
343 if (argno <= inreg) {
344 stack = (uintptr_t *)&rp->r_rdi;
345 } else {
346 stack = (uintptr_t *)(rp->r_rsp);
347 argno -= (inreg + 1);
348 }
349 #endif
350 goto load;
351 }
352 }
353
354 /*
355 * We know that we did not come through a trap to get into
356 * dtrace_probe() -- the provider simply called dtrace_probe()
357 * directly. As this is the case, we need to shift the argument
358 * that we're looking for: the probe ID is the first argument to
359 * dtrace_probe(), so the argument n will actually be found where
360 * one would expect to find argument (n + 1).
361 */
362 argno++;
363
364 #if defined(__amd64)
365 if (argno <= inreg) {
366 /*
367 * This shouldn't happen. If the argument is passed in a
368 * register then it should have been, well, passed in a
369 * register...
370 */
371 DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
372 return (0);
373 }
374
375 argno -= (inreg + 1);
376 #endif
377 stack = (uintptr_t *)&fp[1];
378
379 load:
380 DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
381 val = stack[argno];
382 DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
383
384 return (val);
385 }
386
387 static dtrace_pops_t sdt_pops = {
388 NULL,
389 sdt_provide_module,
390 sdt_enable,
391 sdt_disable,
392 NULL,
393 NULL,
394 sdt_getargdesc,
395 sdt_getarg,
396 NULL,
397 sdt_destroy
398 };
399
400 /*ARGSUSED*/
401 static int
402 sdt_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
403 {
404 sdt_provider_t *prov;
405
406 if (ddi_create_minor_node(devi, "sdt", S_IFCHR,
407 0, DDI_PSEUDO, NULL) == DDI_FAILURE) {
408 cmn_err(CE_NOTE, "/dev/sdt couldn't create minor node");
409 ddi_remove_minor_node(devi, NULL);
410 return (DDI_FAILURE);
411 }
412
413 ddi_report_dev(devi);
414 sdt_devi = devi;
415
416 if (sdt_probetab_size == 0)
417 sdt_probetab_size = SDT_PROBETAB_SIZE;
418
419 sdt_probetab_mask = sdt_probetab_size - 1;
420 sdt_probetab =
421 kmem_zalloc(sdt_probetab_size * sizeof (sdt_probe_t *), KM_SLEEP);
422 dtrace_invop_add(sdt_invop);
423
424 for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
425 uint32_t priv;
426
427 if (prov->sdtp_priv == DTRACE_PRIV_NONE) {
428 priv = DTRACE_PRIV_KERNEL;
429 sdt_pops.dtps_mode = NULL;
430 } else {
431 priv = prov->sdtp_priv;
432 ASSERT(priv == DTRACE_PRIV_USER);
433 sdt_pops.dtps_mode = sdt_mode;
434 }
435
436 if (dtrace_register(prov->sdtp_name, prov->sdtp_attr,
437 priv, NULL, &sdt_pops, prov, &prov->sdtp_id) != 0) {
438 cmn_err(CE_WARN, "failed to register sdt provider %s",
439 prov->sdtp_name);
440 }
441 }
442
443 return (DDI_SUCCESS);
444 }
445
446 /*ARGSUSED*/
447 static int
448 sdt_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
449 {
450 sdt_provider_t *prov;
451
452 switch (cmd) {
453 case DDI_DETACH:
454 break;
455
456 case DDI_SUSPEND:
457 return (DDI_SUCCESS);
458
459 default:
460 return (DDI_FAILURE);
461 }
462
463 for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
464 if (prov->sdtp_id != DTRACE_PROVNONE) {
465 if (dtrace_unregister(prov->sdtp_id) != 0)
466 return (DDI_FAILURE);
467
468 prov->sdtp_id = DTRACE_PROVNONE;
469 }
470 }
471
472 dtrace_invop_remove(sdt_invop);
473 kmem_free(sdt_probetab, sdt_probetab_size * sizeof (sdt_probe_t *));
474
475 return (DDI_SUCCESS);
476 }
477
478 /*ARGSUSED*/
479 static int
480 sdt_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
481 {
482 int error;
483
484 switch (infocmd) {
485 case DDI_INFO_DEVT2DEVINFO:
486 *result = (void *)sdt_devi;
487 error = DDI_SUCCESS;
488 break;
489 case DDI_INFO_DEVT2INSTANCE:
490 *result = (void *)0;
491 error = DDI_SUCCESS;
492 break;
493 default:
494 error = DDI_FAILURE;
495 }
496 return (error);
497 }
498
499 /*ARGSUSED*/
500 static int
501 sdt_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
502 {
503 return (0);
504 }
505
506 static struct cb_ops sdt_cb_ops = {
507 sdt_open, /* open */
508 nodev, /* close */
509 nulldev, /* strategy */
510 nulldev, /* print */
511 nodev, /* dump */
512 nodev, /* read */
513 nodev, /* write */
514 nodev, /* ioctl */
515 nodev, /* devmap */
516 nodev, /* mmap */
517 nodev, /* segmap */
518 nochpoll, /* poll */
519 ddi_prop_op, /* cb_prop_op */
520 0, /* streamtab */
521 D_NEW | D_MP /* Driver compatibility flag */
522 };
523
524 static struct dev_ops sdt_ops = {
525 DEVO_REV, /* devo_rev, */
526 0, /* refcnt */
527 sdt_info, /* get_dev_info */
528 nulldev, /* identify */
529 nulldev, /* probe */
530 sdt_attach, /* attach */
531 sdt_detach, /* detach */
532 nodev, /* reset */
533 &sdt_cb_ops, /* driver operations */
534 NULL, /* bus operations */
535 nodev, /* dev power */
536 ddi_quiesce_not_needed, /* quiesce */
537 };
538
539 /*
540 * Module linkage information for the kernel.
541 */
542 static struct modldrv modldrv = {
543 &mod_driverops, /* module type (this is a pseudo driver) */
544 "Statically Defined Tracing", /* name of module */
545 &sdt_ops, /* driver ops */
546 };
547
548 static struct modlinkage modlinkage = {
549 MODREV_1,
550 (void *)&modldrv,
551 NULL
552 };
553
554 int
555 _init(void)
556 {
557 return (mod_install(&modlinkage));
558 }
559
560 int
561 _info(struct modinfo *modinfop)
562 {
563 return (mod_info(&modlinkage, modinfop));
564 }
565
566 int
567 _fini(void)
568 {
569 return (mod_remove(&modlinkage));
570 }