xref: /illumos-gate/usr/src/uts/intel/dtrace/sdt.c (revision 7c478bd95313f5f23a4c958a745db2134aa03244) 
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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include <sys/modctl.h>
30 #include <sys/sunddi.h>
31 #include <sys/dtrace.h>
32 #include <sys/kobj.h>
33 #include <sys/stat.h>
34 #include <sys/conf.h>
35 #include <vm/seg_kmem.h>
36 #include <sys/stack.h>
37 #include <sys/sdt_impl.h>
38 
39 #define	SDT_PATCHVAL	0xf0
40 #define	SDT_ADDR2NDX(addr)	((((uintptr_t)(addr)) >> 4) & sdt_probetab_mask)
41 #define	SDT_PROBETAB_SIZE	0x1000		/* 4k entries -- 16K total */
42 
43 static dev_info_t		*sdt_devi;
44 static int			sdt_verbose = 0;
45 static sdt_probe_t		**sdt_probetab;
46 static int			sdt_probetab_size;
47 static int			sdt_probetab_mask;
48 
49 /*ARGSUSED*/
50 static int
51 sdt_invop(uintptr_t addr, uintptr_t *stack, uintptr_t eax)
52 {
53 	uintptr_t stack0, stack1, stack2, stack3, stack4;
54 	int i = 0;
55 	sdt_probe_t *sdt = sdt_probetab[SDT_ADDR2NDX(addr)];
56 
57 #ifdef __amd64
58 	/*
59 	 * On amd64, stack[0] contains the dereferenced stack pointer,
60 	 * stack[1] contains savfp, stack[2] contains savpc.  We want
61 	 * to step over these entries.
62 	 */
63 	i += 3;
64 #endif
65 
66 	for (; sdt != NULL; sdt = sdt->sdp_hashnext) {
67 		if ((uintptr_t)sdt->sdp_patchpoint == addr) {
68 			/*
69 			 * When accessing the arguments on the stack, we must
70 			 * protect against accessing beyond the stack.  We can
71 			 * safely set NOFAULT here -- we know that interrupts
72 			 * are already disabled.
73 			 */
74 			DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
75 			stack0 = stack[i++];
76 			stack1 = stack[i++];
77 			stack2 = stack[i++];
78 			stack3 = stack[i++];
79 			stack4 = stack[i++];
80 			DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT |
81 			    CPU_DTRACE_BADADDR);
82 
83 			dtrace_probe(sdt->sdp_id, stack0, stack1,
84 			    stack2, stack3, stack4);
85 
86 			return (DTRACE_INVOP_NOP);
87 		}
88 	}
89 
90 	return (0);
91 }
92 
93 /*ARGSUSED*/
94 static void
95 sdt_provide_module(void *arg, struct modctl *ctl)
96 {
97 	struct module *mp = ctl->mod_mp;
98 	char *modname = ctl->mod_modname;
99 	sdt_probedesc_t *sdpd;
100 	sdt_probe_t *sdp, *old;
101 	sdt_provider_t *prov;
102 	int len;
103 
104 	/*
105 	 * One for all, and all for one:  if we haven't yet registered all of
106 	 * our providers, we'll refuse to provide anything.
107 	 */
108 	for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
109 		if (prov->sdtp_id == DTRACE_PROVNONE)
110 			return;
111 	}
112 
113 	if (mp->sdt_nprobes != 0 || (sdpd = mp->sdt_probes) == NULL)
114 		return;
115 
116 	for (sdpd = mp->sdt_probes; sdpd != NULL; sdpd = sdpd->sdpd_next) {
117 		char *name = sdpd->sdpd_name, *func, *nname;
118 		int i, j;
119 		sdt_provider_t *prov;
120 		ulong_t offs;
121 		dtrace_id_t id;
122 
123 		for (prov = sdt_providers; prov->sdtp_prefix != NULL; prov++) {
124 			char *prefix = prov->sdtp_prefix;
125 
126 			if (strncmp(name, prefix, strlen(prefix)) == 0) {
127 				name += strlen(prefix);
128 				break;
129 			}
130 		}
131 
132 		nname = kmem_alloc(len = strlen(name) + 1, KM_SLEEP);
133 
134 		for (i = 0, j = 0; name[j] != '\0'; i++) {
135 			if (name[j] == '_' && name[j + 1] == '_') {
136 				nname[i] = '-';
137 				j += 2;
138 			} else {
139 				nname[i] = name[j++];
140 			}
141 		}
142 
143 		nname[i] = '\0';
144 
145 		sdp = kmem_zalloc(sizeof (sdt_probe_t), KM_SLEEP);
146 		sdp->sdp_loadcnt = ctl->mod_loadcnt;
147 		sdp->sdp_ctl = ctl;
148 		sdp->sdp_name = nname;
149 		sdp->sdp_namelen = len;
150 		sdp->sdp_provider = prov;
151 
152 		func = kobj_searchsym(mp, sdpd->sdpd_offset, &offs);
153 
154 		if (func == NULL)
155 			func = "<unknown>";
156 
157 		/*
158 		 * We have our provider.  Now create the probe.
159 		 */
160 		if ((id = dtrace_probe_lookup(prov->sdtp_id, modname,
161 		    func, nname)) != DTRACE_IDNONE) {
162 			old = dtrace_probe_arg(prov->sdtp_id, id);
163 			ASSERT(old != NULL);
164 
165 			sdp->sdp_next = old->sdp_next;
166 			sdp->sdp_id = id;
167 			old->sdp_next = sdp;
168 		} else {
169 			sdp->sdp_id = dtrace_probe_create(prov->sdtp_id,
170 			    modname, func, nname, 3, sdp);
171 
172 			mp->sdt_nprobes++;
173 		}
174 
175 		sdp->sdp_hashnext =
176 		    sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)];
177 		sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)] = sdp;
178 
179 		sdp->sdp_patchval = SDT_PATCHVAL;
180 		sdp->sdp_patchpoint = (uint8_t *)sdpd->sdpd_offset;
181 		sdp->sdp_savedval = *sdp->sdp_patchpoint;
182 	}
183 }
184 
185 /*ARGSUSED*/
186 static void
187 sdt_destroy(void *arg, dtrace_id_t id, void *parg)
188 {
189 	sdt_probe_t *sdp = parg, *old, *last, *hash;
190 	struct modctl *ctl = sdp->sdp_ctl;
191 	int ndx;
192 
193 	if (ctl != NULL && ctl->mod_loadcnt == sdp->sdp_loadcnt) {
194 		if ((ctl->mod_loadcnt == sdp->sdp_loadcnt &&
195 		    ctl->mod_loaded)) {
196 			((struct module *)(ctl->mod_mp))->sdt_nprobes--;
197 		}
198 	}
199 
200 	while (sdp != NULL) {
201 		old = sdp;
202 
203 		/*
204 		 * Now we need to remove this probe from the sdt_probetab.
205 		 */
206 		ndx = SDT_ADDR2NDX(sdp->sdp_patchpoint);
207 		last = NULL;
208 		hash = sdt_probetab[ndx];
209 
210 		while (hash != sdp) {
211 			ASSERT(hash != NULL);
212 			last = hash;
213 			hash = hash->sdp_hashnext;
214 		}
215 
216 		if (last != NULL) {
217 			last->sdp_hashnext = sdp->sdp_hashnext;
218 		} else {
219 			sdt_probetab[ndx] = sdp->sdp_hashnext;
220 		}
221 
222 		kmem_free(sdp->sdp_name, sdp->sdp_namelen);
223 		sdp = sdp->sdp_next;
224 		kmem_free(old, sizeof (sdt_probe_t));
225 	}
226 }
227 
228 /*ARGSUSED*/
229 static void
230 sdt_enable(void *arg, dtrace_id_t id, void *parg)
231 {
232 	sdt_probe_t *sdp = parg;
233 	struct modctl *ctl = sdp->sdp_ctl;
234 
235 	ctl->mod_nenabled++;
236 
237 	/*
238 	 * If this module has disappeared since we discovered its probes,
239 	 * refuse to enable it.
240 	 */
241 	if (!ctl->mod_loaded) {
242 		if (sdt_verbose) {
243 			cmn_err(CE_NOTE, "sdt is failing for probe %s "
244 			    "(module %s unloaded)",
245 			    sdp->sdp_name, ctl->mod_modname);
246 		}
247 		goto err;
248 	}
249 
250 	/*
251 	 * Now check that our modctl has the expected load count.  If it
252 	 * doesn't, this module must have been unloaded and reloaded -- and
253 	 * we're not going to touch it.
254 	 */
255 	if (ctl->mod_loadcnt != sdp->sdp_loadcnt) {
256 		if (sdt_verbose) {
257 			cmn_err(CE_NOTE, "sdt is failing for probe %s "
258 			    "(module %s reloaded)",
259 			    sdp->sdp_name, ctl->mod_modname);
260 		}
261 		goto err;
262 	}
263 
264 	while (sdp != NULL) {
265 		*sdp->sdp_patchpoint = sdp->sdp_patchval;
266 		sdp = sdp->sdp_next;
267 	}
268 err:
269 	;
270 }
271 
272 /*ARGSUSED*/
273 static void
274 sdt_disable(void *arg, dtrace_id_t id, void *parg)
275 {
276 	sdt_probe_t *sdp = parg;
277 	struct modctl *ctl = sdp->sdp_ctl;
278 
279 	ctl->mod_nenabled--;
280 
281 	if (!ctl->mod_loaded || ctl->mod_loadcnt != sdp->sdp_loadcnt)
282 		goto err;
283 
284 	while (sdp != NULL) {
285 		*sdp->sdp_patchpoint = sdp->sdp_savedval;
286 		sdp = sdp->sdp_next;
287 	}
288 
289 err:
290 	;
291 }
292 
293 static dtrace_pops_t sdt_pops = {
294 	NULL,
295 	sdt_provide_module,
296 	sdt_enable,
297 	sdt_disable,
298 	NULL,
299 	NULL,
300 	sdt_getargdesc,
301 	NULL,
302 	NULL,
303 	sdt_destroy
304 };
305 
306 /*ARGSUSED*/
307 static int
308 sdt_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
309 {
310 	sdt_provider_t *prov;
311 
312 	if (ddi_create_minor_node(devi, "sdt", S_IFCHR,
313 	    0, DDI_PSEUDO, NULL) == DDI_FAILURE) {
314 		cmn_err(CE_NOTE, "/dev/sdt couldn't create minor node");
315 		ddi_remove_minor_node(devi, NULL);
316 		return (DDI_FAILURE);
317 	}
318 
319 	ddi_report_dev(devi);
320 	sdt_devi = devi;
321 
322 	if (sdt_probetab_size == 0)
323 		sdt_probetab_size = SDT_PROBETAB_SIZE;
324 
325 	sdt_probetab_mask = sdt_probetab_size - 1;
326 	sdt_probetab =
327 	    kmem_zalloc(sdt_probetab_size * sizeof (sdt_probe_t *), KM_SLEEP);
328 	dtrace_invop_add(sdt_invop);
329 
330 	for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
331 		if (dtrace_register(prov->sdtp_name, prov->sdtp_attr,
332 		    DTRACE_PRIV_KERNEL, 0,
333 		    &sdt_pops, prov, &prov->sdtp_id) != 0) {
334 			cmn_err(CE_WARN, "failed to register sdt provider %s",
335 			    prov->sdtp_name);
336 		}
337 	}
338 
339 	return (DDI_SUCCESS);
340 }
341 
342 /*ARGSUSED*/
343 static int
344 sdt_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
345 {
346 	sdt_provider_t *prov;
347 
348 	switch (cmd) {
349 	case DDI_DETACH:
350 		break;
351 
352 	case DDI_SUSPEND:
353 		return (DDI_SUCCESS);
354 
355 	default:
356 		return (DDI_FAILURE);
357 	}
358 
359 	for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
360 		if (prov->sdtp_id != DTRACE_PROVNONE) {
361 			if (dtrace_unregister(prov->sdtp_id) != 0)
362 				return (DDI_FAILURE);
363 
364 			prov->sdtp_id = DTRACE_PROVNONE;
365 		}
366 	}
367 
368 	dtrace_invop_remove(sdt_invop);
369 	kmem_free(sdt_probetab, sdt_probetab_size * sizeof (sdt_probe_t *));
370 
371 	return (DDI_SUCCESS);
372 }
373 
374 /*ARGSUSED*/
375 static int
376 sdt_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
377 {
378 	int error;
379 
380 	switch (infocmd) {
381 	case DDI_INFO_DEVT2DEVINFO:
382 		*result = (void *)sdt_devi;
383 		error = DDI_SUCCESS;
384 		break;
385 	case DDI_INFO_DEVT2INSTANCE:
386 		*result = (void *)0;
387 		error = DDI_SUCCESS;
388 		break;
389 	default:
390 		error = DDI_FAILURE;
391 	}
392 	return (error);
393 }
394 
395 /*ARGSUSED*/
396 static int
397 sdt_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
398 {
399 	return (0);
400 }
401 
402 static struct cb_ops sdt_cb_ops = {
403 	sdt_open,		/* open */
404 	nodev,			/* close */
405 	nulldev,		/* strategy */
406 	nulldev,		/* print */
407 	nodev,			/* dump */
408 	nodev,			/* read */
409 	nodev,			/* write */
410 	nodev,			/* ioctl */
411 	nodev,			/* devmap */
412 	nodev,			/* mmap */
413 	nodev,			/* segmap */
414 	nochpoll,		/* poll */
415 	ddi_prop_op,		/* cb_prop_op */
416 	0,			/* streamtab  */
417 	D_NEW | D_MP		/* Driver compatibility flag */
418 };
419 
420 static struct dev_ops sdt_ops = {
421 	DEVO_REV,		/* devo_rev, */
422 	0,			/* refcnt  */
423 	sdt_info,		/* get_dev_info */
424 	nulldev,		/* identify */
425 	nulldev,		/* probe */
426 	sdt_attach,		/* attach */
427 	sdt_detach,		/* detach */
428 	nodev,			/* reset */
429 	&sdt_cb_ops,		/* driver operations */
430 	NULL,			/* bus operations */
431 	nodev			/* dev power */
432 };
433 
434 /*
435  * Module linkage information for the kernel.
436  */
437 static struct modldrv modldrv = {
438 	&mod_driverops,		/* module type (this is a pseudo driver) */
439 	"Statically Defined Tracing",	/* name of module */
440 	&sdt_ops,		/* driver ops */
441 };
442 
443 static struct modlinkage modlinkage = {
444 	MODREV_1,
445 	(void *)&modldrv,
446 	NULL
447 };
448 
449 int
450 _init(void)
451 {
452 	return (mod_install(&modlinkage));
453 }
454 
455 int
456 _info(struct modinfo *modinfop)
457 {
458 	return (mod_info(&modlinkage, modinfop));
459 }
460 
461 int
462 _fini(void)
463 {
464 	return (mod_remove(&modlinkage));
465 }
466