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
55static const char *devname = "/dev/dtrace/helper";
56static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
57
58static const char *modname;	/* Name of this load object */
59static int gen;			/* DOF helper generation */
60extern dof_hdr_t __SUNW_dof;	/* DOF defined in the .SUNW_dof section */
61static boolean_t dof_init_debug = B_FALSE;	/* From DTRACE_DOF_INIT_DEBUG */
62
63static void
64dprintf(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)
87static void
88dtrace_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)
174static void
175dtrace_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