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 2008 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #include <unistd.h>
27 #include <fcntl.h>
28 #include <dlfcn.h>
29 #include <link.h>
30 #include <sys/dtrace.h>
31
32 #include <stdarg.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <errno.h>
37
38 /*
39 * In Solaris 10 GA, the only mechanism for communicating helper information
40 * is through the DTrace helper pseudo-device node in /devices; there is
41 * no /dev link. Because of this, USDT providers and helper actions don't
42 * work inside of non-global zones. This issue was addressed by adding
43 * the /dev and having this initialization code use that /dev link. If the
44 * /dev link doesn't exist it falls back to looking for the /devices node
45 * as this code may be embedded in a binary which runs on Solaris 10 GA.
46 *
47 * Users may set the following environment variable to affect the way
48 * helper initialization takes place:
49 *
50 * DTRACE_DOF_INIT_DEBUG enable debugging output
51 * DTRACE_DOF_INIT_DISABLE disable helper loading
52 * DTRACE_DOF_INIT_DEVNAME set the path to the helper node
53 */
54
55 static const char *devname = "/dev/dtrace/helper";
56 static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
57
58 static const char *modname; /* Name of this load object */
59 static int gen; /* DOF helper generation */
60 extern dof_hdr_t __SUNW_dof; /* DOF defined in the .SUNW_dof section */
61 static boolean_t dof_init_debug = B_FALSE; /* From DTRACE_DOF_INIT_DEBUG */
62
63 static void
dprintf(int debug,const char * fmt,...)64 dprintf(int debug, const char *fmt, ...)
65 {
66 va_list ap;
67
68 if (debug && !dof_init_debug)
69 return;
70
71 va_start(ap, fmt);
72
73 if (modname == NULL)
74 (void) fprintf(stderr, "dtrace DOF: ");
75 else
76 (void) fprintf(stderr, "dtrace DOF %s: ", modname);
77
78 (void) vfprintf(stderr, fmt, ap);
79
80 if (fmt[strlen(fmt) - 1] != '\n')
81 (void) fprintf(stderr, ": %s\n", strerror(errno));
82
83 va_end(ap);
84 }
85
86 #pragma init(dtrace_dof_init)
87 static void
dtrace_dof_init(void)88 dtrace_dof_init(void)
89 {
90 dof_hdr_t *dof = &__SUNW_dof;
91 #ifdef _LP64
92 Elf64_Ehdr *elf;
93 #else
94 Elf32_Ehdr *elf;
95 #endif
96 dof_helper_t dh;
97 Link_map *lmp;
98 Lmid_t lmid;
99 int fd;
100 const char *p;
101
102 if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
103 return;
104
105 if (getenv("DTRACE_DOF_INIT_DEBUG") != NULL)
106 dof_init_debug = B_TRUE;
107
108 if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lmp) == -1 || lmp == NULL) {
109 dprintf(1, "couldn't discover module name or address\n");
110 return;
111 }
112
113 if (dlinfo(RTLD_SELF, RTLD_DI_LMID, &lmid) == -1) {
114 dprintf(1, "couldn't discover link map ID\n");
115 return;
116 }
117
118 if ((modname = strrchr(lmp->l_name, '/')) == NULL)
119 modname = lmp->l_name;
120 else
121 modname++;
122
123 if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
124 dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
125 dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
126 dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
127 dprintf(0, ".SUNW_dof section corrupt\n");
128 return;
129 }
130
131 elf = (void *)lmp->l_addr;
132
133 dh.dofhp_dof = (uintptr_t)dof;
134 dh.dofhp_addr = elf->e_type == ET_DYN ? lmp->l_addr : 0;
135
136 if (lmid == 0) {
137 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
138 "%s", modname);
139 } else {
140 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
141 "LM%lu`%s", lmid, modname);
142 }
143
144 if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
145 devname = p;
146
147 if ((fd = open64(devname, O_RDWR)) < 0) {
148 dprintf(1, "failed to open helper device %s", devname);
149
150 /*
151 * If the device path wasn't explicitly set, try again with
152 * the old device path.
153 */
154 if (p != NULL)
155 return;
156
157 devname = olddevname;
158
159 if ((fd = open64(devname, O_RDWR)) < 0) {
160 dprintf(1, "failed to open helper device %s", devname);
161 return;
162 }
163 }
164
165 if ((gen = ioctl(fd, DTRACEHIOC_ADDDOF, &dh)) == -1)
166 dprintf(1, "DTrace ioctl failed for DOF at %p", dof);
167 else
168 dprintf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);
169
170 (void) close(fd);
171 }
172
173 #pragma fini(dtrace_dof_fini)
174 static void
dtrace_dof_fini(void)175 dtrace_dof_fini(void)
176 {
177 int fd;
178
179 if ((fd = open64(devname, O_RDWR)) < 0) {
180 dprintf(1, "failed to open helper device %s", devname);
181 return;
182 }
183
184 if ((gen = ioctl(fd, DTRACEHIOC_REMOVE, gen)) == -1)
185 dprintf(1, "DTrace ioctl failed to remove DOF (%d)\n", gen);
186 else
187 dprintf(1, "DTrace ioctl removed DOF (%d)\n", gen);
188
189 (void) close(fd);
190 }
191