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