xref: /freebsd/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c (revision 39beb93c3f8bdbf72a61fda42300b5ebed7390c8)
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 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include <unistd.h>
30 #include <fcntl.h>
31 #include <dlfcn.h>
32 #include <link.h>
33 #include <sys/dtrace.h>
34 
35 #include <stdarg.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <errno.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 static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
60 
61 static const char *modname;	/* Name of this load object */
62 static int gen;			/* DOF helper generation */
63 extern dof_hdr_t __SUNW_dof;	/* DOF defined in the .SUNW_dof section */
64 
65 static void
66 dprintf(int debug, const char *fmt, ...)
67 {
68 	va_list ap;
69 
70 	if (debug && getenv("DTRACE_DOF_INIT_DEBUG") == NULL)
71 		return;
72 
73 	va_start(ap, fmt);
74 
75 	if (modname == NULL)
76 		(void) fprintf(stderr, "dtrace DOF: ");
77 	else
78 		(void) fprintf(stderr, "dtrace DOF %s: ", modname);
79 
80 	(void) vfprintf(stderr, fmt, ap);
81 
82 	if (fmt[strlen(fmt) - 1] != '\n')
83 		(void) fprintf(stderr, ": %s\n", strerror(errno));
84 
85 	va_end(ap);
86 }
87 
88 #if defined(sun)
89 #pragma init(dtrace_dof_init)
90 #else
91 static void dtrace_dof_init(void) __attribute__ ((constructor));
92 #endif
93 
94 static void
95 dtrace_dof_init(void)
96 {
97 	dof_hdr_t *dof = &__SUNW_dof;
98 #ifdef _LP64
99 	Elf64_Ehdr *elf;
100 #else
101 	Elf32_Ehdr *elf;
102 #endif
103 	dof_helper_t dh;
104 #if defined(sun)
105 	Link_map *lmp;
106 	Lmid_t lmid;
107 #else
108 	struct link_map *lmp;
109 	u_long lmid = 0;
110 #endif
111 	int fd;
112 	const char *p;
113 
114 	if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
115 		return;
116 
117 	if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lmp) == -1 || lmp == NULL) {
118 		dprintf(1, "couldn't discover module name or address\n");
119 		return;
120 	}
121 
122 #if defined(sun)
123 	if (dlinfo(RTLD_SELF, RTLD_DI_LMID, &lmid) == -1) {
124 		dprintf(1, "couldn't discover link map ID\n");
125 		return;
126 	}
127 #endif
128 
129 	if ((modname = strrchr(lmp->l_name, '/')) == NULL)
130 		modname = lmp->l_name;
131 	else
132 		modname++;
133 
134 	if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
135 	    dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
136 	    dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
137 	    dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
138 		dprintf(0, ".SUNW_dof section corrupt\n");
139 		return;
140 	}
141 
142 	elf = (void *)lmp->l_addr;
143 
144 	dh.dofhp_dof = (uintptr_t)dof;
145 	dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
146 
147 	if (lmid == 0) {
148 		(void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
149 		    "%s", modname);
150 	} else {
151 		(void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
152 		    "LM%lu`%s", lmid, modname);
153 	}
154 
155 	if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
156 		devnamep = p;
157 
158 	if ((fd = open64(devnamep, O_RDWR)) < 0) {
159 		dprintf(1, "failed to open helper device %s", devnamep);
160 
161 		/*
162 		 * If the device path wasn't explicitly set, try again with
163 		 * the old device path.
164 		 */
165 		if (p != NULL)
166 			return;
167 
168 		devnamep = olddevname;
169 
170 		if ((fd = open64(devnamep, O_RDWR)) < 0) {
171 			dprintf(1, "failed to open helper device %s", devnamep);
172 			return;
173 		}
174 	}
175 
176 	if ((gen = ioctl(fd, DTRACEHIOC_ADDDOF, &dh)) == -1)
177 		dprintf(1, "DTrace ioctl failed for DOF at %p", dof);
178 	else
179 		dprintf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);
180 
181 	(void) close(fd);
182 }
183 
184 #if defined(sun)
185 #pragma fini(dtrace_dof_fini)
186 #else
187 static void dtrace_dof_fini(void) __attribute__ ((destructor));
188 #endif
189 
190 static void
191 dtrace_dof_fini(void)
192 {
193 	int fd;
194 
195 	if ((fd = open64(devnamep, O_RDWR)) < 0) {
196 		dprintf(1, "failed to open helper device %s", devnamep);
197 		return;
198 	}
199 
200 	if ((gen = ioctl(fd, DTRACEHIOC_REMOVE, gen)) == -1)
201 		dprintf(1, "DTrace ioctl failed to remove DOF (%d)\n", gen);
202 	else
203 		dprintf(1, "DTrace ioctl removed DOF (%d)\n", gen);
204 
205 	(void) close(fd);
206 }
207