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
58static const char *devnamep = "/dev/dtrace/helper";
59#ifdef illumos
60static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
61#endif
62
63static const char *modname;	/* Name of this load object */
64static int gen;			/* DOF helper generation */
65extern dof_hdr_t __SUNW_dof;	/* DOF defined in the .SUNW_dof section */
66static boolean_t dof_init_debug = B_FALSE;	/* From DTRACE_DOF_INIT_DEBUG */
67
68static void
69dbg_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
94static void dtrace_dof_init(void) __attribute__ ((constructor));
95#endif
96
97static void
98dtrace_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
207static void dtrace_dof_fini(void) __attribute__ ((destructor));
208#endif
209
210static void
211dtrace_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