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 * Copyright 2013 Voxer Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include <sys/types.h>
28 #include <unistd.h>
29 #include <fcntl.h>
30 #include <dlfcn.h>
31 #include <link.h>
32 #include <sys/dtrace.h>
33
34 #include <stdarg.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <errno.h>
39 #include <libelf.h>
40
41 /*
42 * In Solaris 10 GA, the only mechanism for communicating helper information
43 * is through the DTrace helper pseudo-device node in /devices; there is
44 * no /dev link. Because of this, USDT providers and helper actions don't
45 * work inside of non-global zones. This issue was addressed by adding
46 * the /dev and having this initialization code use that /dev link. If the
47 * /dev link doesn't exist it falls back to looking for the /devices node
48 * as this code may be embedded in a binary which runs on Solaris 10 GA.
49 *
50 * Users may set the following environment variable to affect the way
51 * helper initialization takes place:
52 *
53 * DTRACE_DOF_INIT_DEBUG enable debugging output
54 * DTRACE_DOF_INIT_DISABLE disable helper loading
55 * DTRACE_DOF_INIT_DEVNAME set the path to the helper node
56 */
57
58 static const char *devnamep = "/dev/dtrace/helper";
59 #ifdef illumos
60 static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
61 #endif
62
63 static const char *modname; /* Name of this load object */
64 static int gen; /* DOF helper generation */
65 extern dof_hdr_t __SUNW_dof; /* DOF defined in the .SUNW_dof section */
66 static boolean_t dof_init_debug = B_FALSE; /* From DTRACE_DOF_INIT_DEBUG */
67
68 static void
dbg_printf(int debug,const char * fmt,...)69 dbg_printf(int debug, const char *fmt, ...)
70 {
71 va_list ap;
72
73 if (debug && !dof_init_debug)
74 return;
75
76 va_start(ap, fmt);
77
78 if (modname == NULL)
79 (void) fprintf(stderr, "dtrace DOF: ");
80 else
81 (void) fprintf(stderr, "dtrace DOF %s: ", modname);
82
83 (void) vfprintf(stderr, fmt, ap);
84
85 if (fmt[strlen(fmt) - 1] != '\n')
86 (void) fprintf(stderr, ": %s\n", strerror(errno));
87
88 va_end(ap);
89 }
90
91 #ifdef illumos
92 #pragma init(dtrace_dof_init)
93 #else
94 static void dtrace_dof_init(void) __attribute__ ((constructor));
95 #endif
96
97 static void
dtrace_dof_init(void)98 dtrace_dof_init(void)
99 {
100 dof_hdr_t *dof = &__SUNW_dof;
101 #ifdef _LP64
102 Elf64_Ehdr *elf;
103 #else
104 Elf32_Ehdr *elf;
105 #endif
106 dof_helper_t dh;
107 Link_map *lmp = NULL;
108 #ifdef illumos
109 Lmid_t lmid;
110 #else
111 u_long lmid = 0;
112 #endif
113 int fd;
114 const char *p;
115
116 if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
117 return;
118
119 if (getenv("DTRACE_DOF_INIT_DEBUG") != NULL)
120 dof_init_debug = B_TRUE;
121
122 if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lmp) == -1 || lmp == NULL) {
123 dbg_printf(1, "couldn't discover module name or address\n");
124 return;
125 }
126
127 #ifdef illumos
128 if (dlinfo(RTLD_SELF, RTLD_DI_LMID, &lmid) == -1) {
129 dbg_printf(1, "couldn't discover link map ID\n");
130 return;
131 }
132 #endif
133
134 if ((modname = strrchr(lmp->l_name, '/')) == NULL)
135 modname = lmp->l_name;
136 else
137 modname++;
138
139 if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
140 dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
141 dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
142 dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
143 dbg_printf(0, ".SUNW_dof section corrupt\n");
144 return;
145 }
146
147 #ifdef __FreeBSD__
148 elf = (void *)lmp->l_base;
149 #else
150 elf = (void *)lmp->l_addr;
151 #endif
152
153 dh.dofhp_dof = (uintptr_t)dof;
154 #ifdef __FreeBSD__
155 dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_base : 0;
156 dh.dofhp_pid = getpid();
157 #else
158 dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
159 #endif
160
161 if (lmid == 0) {
162 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
163 "%s", modname);
164 } else {
165 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
166 "LM%lu`%s", lmid, modname);
167 }
168
169 if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
170 devnamep = p;
171
172 if ((fd = open64(devnamep, O_RDWR)) < 0) {
173 dbg_printf(1, "failed to open helper device %s", devnamep);
174 #ifdef illumos
175 /*
176 * If the device path wasn't explicitly set, try again with
177 * the old device path.
178 */
179 if (p != NULL)
180 return;
181
182 devnamep = olddevname;
183
184 if ((fd = open64(devnamep, O_RDWR)) < 0) {
185 dbg_printf(1, "failed to open helper device %s", devnamep);
186 return;
187 }
188 #else
189 return;
190 #endif
191 }
192 if ((gen = ioctl(fd, DTRACEHIOC_ADDDOF, &dh)) == -1)
193 dbg_printf(1, "DTrace ioctl failed for DOF at %p", dof);
194 else {
195 dbg_printf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);
196 #ifdef __FreeBSD__
197 gen = dh.dofhp_gen;
198 #endif
199 }
200
201 (void) close(fd);
202 }
203
204 #ifdef illumos
205 #pragma fini(dtrace_dof_fini)
206 #else
207 static void dtrace_dof_fini(void) __attribute__ ((destructor));
208 #endif
209
210 static void
dtrace_dof_fini(void)211 dtrace_dof_fini(void)
212 {
213 int fd;
214
215 if ((fd = open64(devnamep, O_RDWR)) < 0) {
216 dbg_printf(1, "failed to open helper device %s", devnamep);
217 return;
218 }
219
220 if ((gen = ioctl(fd, DTRACEHIOC_REMOVE, &gen)) == -1)
221 dbg_printf(1, "DTrace ioctl failed to remove DOF (%d)\n", gen);
222 else
223 dbg_printf(1, "DTrace ioctl removed DOF (%d)\n", gen);
224
225 (void) close(fd);
226 }
227