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 /*
28 * XXX Hack: Force the use of sys/exec_elf.h, not elfdefinitions.h.
29 * Why?
30 *
31 * - sys/dtrace.h is needed because (XXX why?).
32 * => sys/dtrace.h pulls in sys/ctf_api.h
33 * => which pulls in sys/elf.h
34 * => which pulls in elfdefinitions.h (XXX should it?)
35 *
36 * - link.h is needed for Link_map.
37 * => link.h pulls in link_elf.h
38 * => which pulls in sys/exec_elf.h
39 *
40 * But elfdefinitions.h and sys/exec_elf.h collide over most basic ELF
41 * definitions. Since we don't need elfdefinitions.h otherwise, prefer
42 * sys/exec_elf.h.
43 */
44 #define _SYS_ELFDEFINITIONS_H_
45
46 #include <unistd.h>
47 #include <fcntl.h>
48 #include <dlfcn.h>
49 #include <link.h>
50 #include <sys/dtrace.h>
51 #include <sys/ioctl.h>
52
53 #include <stdarg.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <errno.h>
58 #include <libelf.h>
59
60 /*
61 * In Solaris 10 GA, the only mechanism for communicating helper information
62 * is through the DTrace helper pseudo-device node in /devices; there is
63 * no /dev link. Because of this, USDT providers and helper actions don't
64 * work inside of non-global zones. This issue was addressed by adding
65 * the /dev and having this initialization code use that /dev link. If the
66 * /dev link doesn't exist it falls back to looking for the /devices node
67 * as this code may be embedded in a binary which runs on Solaris 10 GA.
68 *
69 * Users may set the following environment variable to affect the way
70 * helper initialization takes place:
71 *
72 * DTRACE_DOF_INIT_DEBUG enable debugging output
73 * DTRACE_DOF_INIT_DISABLE disable helper loading
74 * DTRACE_DOF_INIT_DEVNAME set the path to the helper node
75 */
76
77 static const char *devnamep = "/dev/dtrace/helper";
78 #ifdef illumos
79 static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
80 #endif
81
82 static const char *modname; /* Name of this load object */
83 static int gen; /* DOF helper generation */
84 extern dof_hdr_t __SUNW_dof; /* DOF defined in the .SUNW_dof section */
85 static boolean_t dof_init_debug = B_FALSE; /* From DTRACE_DOF_INIT_DEBUG */
86
87 static void __printflike(2,3)
dbg_printf(int debug,const char * fmt,...)88 dbg_printf(int debug, const char *fmt, ...)
89 {
90 va_list ap;
91
92 if (debug && !dof_init_debug)
93 return;
94
95 va_start(ap, fmt);
96
97 if (modname == NULL)
98 (void) fprintf(stderr, "dtrace DOF: ");
99 else
100 (void) fprintf(stderr, "dtrace DOF %s: ", modname);
101
102 (void) vfprintf(stderr, fmt, ap);
103
104 if (fmt[strlen(fmt) - 1] != '\n')
105 (void) fprintf(stderr, ": %s\n", strerror(errno));
106
107 va_end(ap);
108 }
109
110 #ifdef illumos
111 #pragma init(dtrace_dof_init)
112 #else
113 static void dtrace_dof_init(void) __attribute__ ((constructor));
114 #endif
115
116 static void
dtrace_dof_init(void)117 dtrace_dof_init(void)
118 {
119 dof_hdr_t *dof = &__SUNW_dof;
120 #ifdef _LP64
121 Elf64_Ehdr *elf;
122 #else
123 Elf32_Ehdr *elf;
124 #endif
125 dof_helper_t dh;
126 Link_map *lmp = NULL;
127 #ifdef illumos
128 Lmid_t lmid;
129 #else
130 u_long lmid = 0;
131 #endif
132 int fd;
133 const char *p;
134
135 if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
136 return;
137
138 if (getenv("DTRACE_DOF_INIT_DEBUG") != NULL)
139 dof_init_debug = B_TRUE;
140
141 if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lmp) == -1 || lmp == NULL) {
142 dbg_printf(1, "couldn't discover module name or address\n");
143 return;
144 }
145
146 #ifdef illumos
147 if (dlinfo(RTLD_SELF, RTLD_DI_LMID, &lmid) == -1) {
148 dbg_printf(1, "couldn't discover link map ID\n");
149 return;
150 }
151 #endif
152
153 if ((modname = strrchr(lmp->l_name, '/')) == NULL)
154 modname = lmp->l_name;
155 else
156 modname++;
157
158 if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
159 dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
160 dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
161 dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
162 dbg_printf(0, ".SUNW_dof section corrupt\n");
163 return;
164 }
165
166 elf = (void *)lmp->l_addr;
167
168 dh.dofhp_dof = (uintptr_t)dof;
169 dh.dofhp_addr = elf && elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
170 #if defined(__FreeBSD__) || defined(__NetBSD__)
171 dh.dofhp_pid = getpid();
172 #endif
173
174 if (lmid == 0) {
175 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
176 "%s", modname);
177 } else {
178 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
179 "LM%lu`%s", lmid, modname);
180 }
181
182 if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
183 devnamep = p;
184
185 if ((fd = open64(devnamep, O_RDWR)) < 0) {
186 dbg_printf(1, "failed to open helper device %s", devnamep);
187 #ifdef illumos
188 /*
189 * If the device path wasn't explicitly set, try again with
190 * the old device path.
191 */
192 if (p != NULL)
193 return;
194
195 devnamep = olddevname;
196
197 if ((fd = open64(devnamep, O_RDWR)) < 0) {
198 dbg_printf(1, "failed to open helper device %s", devnamep);
199 return;
200 }
201 #else
202 return;
203 #endif
204 }
205 if ((gen = ioctl(fd, DTRACEHIOC_ADDDOF, &dh)) == -1)
206 dbg_printf(1, "DTrace ioctl failed for DOF at %p", dof);
207 else {
208 dbg_printf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);
209 #if defined(__FreeBSD__) || defined(__NetBSD__)
210 gen = dh.dofhp_gen;
211 #endif
212 }
213
214 (void) close(fd);
215 }
216
217 #ifdef illumos
218 #pragma fini(dtrace_dof_fini)
219 #else
220 static void dtrace_dof_fini(void) __attribute__ ((destructor));
221 #endif
222
223 static void
dtrace_dof_fini(void)224 dtrace_dof_fini(void)
225 {
226 int fd;
227
228 if ((fd = open64(devnamep, O_RDWR)) < 0) {
229 dbg_printf(1, "failed to open helper device %s", devnamep);
230 return;
231 }
232
233 if ((gen = ioctl(fd, DTRACEHIOC_REMOVE, &gen)) == -1)
234 dbg_printf(1, "DTrace ioctl failed to remove DOF (%d)\n", gen);
235 else
236 dbg_printf(1, "DTrace ioctl removed DOF (%d)\n", gen);
237
238 (void) close(fd);
239 }
240