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 (c) 2000-2001 by Sun Microsystems, Inc.
24 * All rights reserved.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29/*
30 * libthread_db (tdb) cache
31 *
32 * In order to properly debug multi-threaded programs, the proc target must be
33 * able to query and modify information such as a thread's register set using
34 * either the native LWP services provided by libproc (if the process is not
35 * linked with libthread), or using the services provided by libthread_db (if
36 * the process is linked with libthread).  Additionally, a process may begin
37 * life as a single-threaded process and then later dlopen() libthread, so we
38 * must be prepared to switch modes on-the-fly.  There are also two possible
39 * libthread implementations (one in /usr/lib and one in /usr/lib/lwp) so we
40 * cannot link mdb against libthread_db directly; instead, we must dlopen the
41 * appropriate libthread_db on-the-fly based on which libthread.so the victim
42 * process has open.  Finally, mdb is designed so that multiple targets can be
43 * active simultaneously, so we could even have *both* libthread_db's open at
44 * the same time.  This might happen if you were looking at two multi-threaded
45 * user processes inside of a crash dump, one using /usr/lib/libthread.so and
46 * the other using /usr/lib/lwp/libthread.so.  To meet these requirements, we
47 * implement a libthread_db "cache" in this file.  The proc target calls
48 * mdb_tdb_load() with the pathname of a libthread_db to load, and if it is
49 * not already open, we dlopen() it, look up the symbols we need to reference,
50 * and fill in an ops vector which we return to the caller.  Once an object is
51 * loaded, we don't bother unloading it unless the entire cache is explicitly
52 * flushed.  This mechanism also has the nice property that we don't bother
53 * loading libthread_db until we need it, so the debugger starts up faster.
54 */
55
56#include <mdb/mdb_tdb.h>
57#include <mdb/mdb_modapi.h>
58#include <mdb/mdb_err.h>
59
60#include <strings.h>
61#include <unistd.h>
62#include <dlfcn.h>
63#include <link.h>
64
65static mdb_tdb_lib_t *tdb_list;
66
67static td_err_e
68tdb_notsup()
69{
70	return (TD_NOCAPAB); /* return thread_db code for not supported */
71}
72
73const mdb_tdb_ops_t *
74mdb_tdb_load(const char *path)
75{
76	td_err_e (*tdb_init)(void);
77	mdb_tdb_lib_t *t;
78	td_err_e err;
79	void *hdl;
80
81	/*
82	 * Search through the existing cache of thread_db libraries and see if
83	 * we have this one loaded already.  If so, just return its ops vector.
84	 */
85	for (t = tdb_list; t != NULL; t = t->tdb_next) {
86		if (strcmp(path, t->tdb_pathname) == 0)
87			break;
88	}
89
90	if (t != NULL)
91		return (&t->tdb_ops);
92
93	/*
94	 * Otherwise dlmopen the new library, look up its td_init() function,
95	 * and call it.  If any of this fails, we return NULL for failure.
96	 */
97	if (access(path, F_OK) == -1)
98		return (NULL);
99
100	if ((hdl = dlmopen(LM_ID_BASE, path, RTLD_LAZY | RTLD_LOCAL)) == NULL) {
101		(void) set_errno(EMDB_RTLD);
102		return (NULL);
103	}
104
105	if ((tdb_init = (td_err_e (*)(void))dlsym(hdl, "td_init")) == NULL) {
106		(void) dlclose(hdl);
107		(void) set_errno(tdb_to_errno(TD_NOCAPAB));
108		return (NULL);
109	}
110
111	if ((err = tdb_init()) != TD_OK) {
112		(void) dlclose(hdl);
113		(void) set_errno(tdb_to_errno(err));
114		return (NULL);
115	}
116
117	/*
118	 * If td_init() succeeds, we can't fail from here on.  Allocate a new
119	 * library entry and add it to our linked list.
120	 */
121	t = mdb_alloc(sizeof (mdb_tdb_lib_t), UM_SLEEP);
122
123	(void) strncpy(t->tdb_pathname, path, MAXPATHLEN);
124	t->tdb_pathname[MAXPATHLEN - 1] = '\0';
125	t->tdb_handle = hdl;
126	t->tdb_next = tdb_list;
127	tdb_list = t;
128
129	/*
130	 * For each function we need to call in the thread_db library, look it
131	 * up using dlsym().  If we find it, add it to the ops vector.  If not,
132	 * put the address of our default function (see above) in that slot.
133	 */
134
135	t->tdb_ops.td_ta_new = (td_err_e (*)())dlsym(hdl, "td_ta_new");
136	if (t->tdb_ops.td_ta_new == NULL)
137		t->tdb_ops.td_ta_new = (td_err_e (*)())tdb_notsup;
138
139	t->tdb_ops.td_ta_delete = (td_err_e (*)())dlsym(hdl, "td_ta_delete");
140	if (t->tdb_ops.td_ta_delete == NULL)
141		t->tdb_ops.td_ta_delete = (td_err_e (*)())tdb_notsup;
142
143	t->tdb_ops.td_ta_thr_iter = (td_err_e (*)())
144	    dlsym(hdl, "td_ta_thr_iter");
145	if (t->tdb_ops.td_ta_thr_iter == NULL)
146		t->tdb_ops.td_ta_thr_iter = (td_err_e (*)())tdb_notsup;
147
148	t->tdb_ops.td_ta_map_id2thr = (td_err_e (*)())
149	    dlsym(hdl, "td_ta_map_id2thr");
150	if (t->tdb_ops.td_ta_map_id2thr == NULL)
151		t->tdb_ops.td_ta_map_id2thr = (td_err_e (*)())tdb_notsup;
152
153	t->tdb_ops.td_ta_map_lwp2thr = (td_err_e (*)())
154	    dlsym(hdl, "td_ta_map_lwp2thr");
155	if (t->tdb_ops.td_ta_map_lwp2thr == NULL)
156		t->tdb_ops.td_ta_map_lwp2thr = (td_err_e (*)())tdb_notsup;
157
158	t->tdb_ops.td_thr_get_info = (td_err_e (*)())
159	    dlsym(hdl, "td_thr_get_info");
160	if (t->tdb_ops.td_thr_get_info == NULL)
161		t->tdb_ops.td_thr_get_info = (td_err_e (*)())tdb_notsup;
162
163	t->tdb_ops.td_thr_getgregs = (td_err_e (*)())
164	    dlsym(hdl, "td_thr_getgregs");
165	if (t->tdb_ops.td_thr_getgregs == NULL)
166		t->tdb_ops.td_thr_getgregs = (td_err_e (*)())tdb_notsup;
167
168	t->tdb_ops.td_thr_setgregs = (td_err_e (*)())
169	    dlsym(hdl, "td_thr_setgregs");
170	if (t->tdb_ops.td_thr_setgregs == NULL)
171		t->tdb_ops.td_thr_setgregs = (td_err_e (*)())tdb_notsup;
172
173	t->tdb_ops.td_thr_getfpregs = (td_err_e (*)())
174	    dlsym(hdl, "td_thr_getfpregs");
175	if (t->tdb_ops.td_thr_getfpregs == NULL)
176		t->tdb_ops.td_thr_getfpregs = (td_err_e (*)())tdb_notsup;
177
178	t->tdb_ops.td_thr_setfpregs = (td_err_e (*)())
179	    dlsym(hdl, "td_thr_setfpregs");
180	if (t->tdb_ops.td_thr_setfpregs == NULL)
181		t->tdb_ops.td_thr_setfpregs = (td_err_e (*)())tdb_notsup;
182
183	t->tdb_ops.td_thr_tlsbase = (td_err_e (*)())
184	    dlsym(hdl, "td_thr_tlsbase");
185	if (t->tdb_ops.td_thr_tlsbase == NULL)
186		t->tdb_ops.td_thr_tlsbase = (td_err_e (*)())tdb_notsup;
187
188#ifdef __sparc
189	t->tdb_ops.td_thr_getxregs = (td_err_e (*)())
190	    dlsym(hdl, "td_thr_getxregs");
191	if (t->tdb_ops.td_thr_getxregs == NULL)
192		t->tdb_ops.td_thr_getxregs = (td_err_e (*)())tdb_notsup;
193
194	t->tdb_ops.td_thr_setxregs = (td_err_e (*)())
195	    dlsym(hdl, "td_thr_setxregs");
196	if (t->tdb_ops.td_thr_setxregs == NULL)
197		t->tdb_ops.td_thr_setxregs = (td_err_e (*)())tdb_notsup;
198#endif	/* __sparc */
199
200	return (&t->tdb_ops);
201}
202
203void
204mdb_tdb_flush(void)
205{
206	mdb_tdb_lib_t *t, *u;
207
208	for (t = tdb_list; t != NULL; t = u) {
209		u = t->tdb_next;
210		(void) dlclose(t->tdb_handle);
211		mdb_free(t, sizeof (mdb_tdb_lib_t));
212	}
213
214	tdb_list = NULL;
215}
216