1 /* $NetBSD: initfini.c,v 1.17 2024/01/20 14:52:48 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2007 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Andrew Doran.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __RCSID("$NetBSD: initfini.c,v 1.17 2024/01/20 14:52:48 christos Exp $");
34
35 #ifdef _LIBC
36 #include "namespace.h"
37 #endif
38
39 #include <sys/param.h>
40 #include <sys/exec.h>
41 #include <sys/tls.h>
42 #include <stdbool.h>
43 #include "extern.h"
44 #include "csu-common.h"
45
46 void __guard_setup(void);
47 void __libc_thr_init(void);
48 void __libc_atexit_init(void);
49 void __libc_env_init(void);
50
51 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
52 __dso_hidden void __libc_static_tls_setup(void);
53 #endif
54
55 #ifdef __weak_alias
56 __weak_alias(_dlauxinfo,___dlauxinfo)
57 static void *__libc_dlauxinfo;
58
59 void *___dlauxinfo(void) __pure;
60 __weakref_visible void * real_dlauxinfo(void) __weak_reference(_dlauxinfo);
61
62 void *
___dlauxinfo(void)63 ___dlauxinfo(void)
64 {
65 return __libc_dlauxinfo;
66 }
67 #endif
68
69 static bool libc_initialised;
70
71 /*
72 * Declare as common symbol to allow new libc with older binaries to
73 * not trigger an undefined reference.
74 */
75 struct ps_strings *__ps_strings __common;
76 char *__progname __common;
77 char **environ __common;
78
79 /*
80 * _libc_init is called twice. One call comes explicitly from crt0.o
81 * (for newer versions) and the other is via global constructor handling.
82 *
83 * In static binaries the explicit call is first; in dynamically linked
84 * binaries the global constructors of libc are called from ld.elf_so
85 * before crt0.o is reached.
86 *
87 * Note that __ps_strings is set by crt0.o. So in the dynamic case, it
88 * hasn't been set yet when we get here, and __libc_dlauxinfo is not
89 * (ever) assigned. But this is ok because __libc_dlauxinfo is only
90 * used in static binaries, because it's there to substitute for the
91 * dynamic linker. In static binaries __ps_strings will have been set
92 * up when we get here and we get a valid __libc_dlauxinfo.
93 *
94 * This code causes problems for Emacs because Emacs's undump
95 * mechanism saves the __ps_strings value from the startup execution;
96 * then running the resulting binary it gets here before crt0 has
97 * assigned the current execution's value to __ps_strings, and in an
98 * environment with ASLR this can cause the assignment of
99 * __libc_dlauxinfo to receive SIGSEGV.
100 */
101 void __section(".text.startup")
_libc_init(void)102 _libc_init(void)
103 {
104
105 if (libc_initialised)
106 return;
107
108 libc_initialised = 1;
109
110 /* Only initialize _dlauxinfo for static binaries. */
111 if (__ps_strings != NULL && real_dlauxinfo == ___dlauxinfo)
112 __libc_dlauxinfo = __ps_strings->ps_argvstr +
113 __ps_strings->ps_nargvstr + __ps_strings->ps_nenvstr + 2;
114
115 /* For -fstack-protector */
116 __guard_setup();
117
118 /* Atomic operations */
119 __libc_atomic_init();
120
121 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
122 /* Initialize TLS for statically linked programs. */
123 __libc_static_tls_setup();
124 #endif
125
126 /* Threads */
127 __libc_thr_init();
128
129 /* Initialize the atexit mutexes */
130 __libc_atexit_init();
131 }
132