1 /* $NetBSD: initfini.c,v 1.15 2021/04/20 21:42:32 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 1.15 2021/04/20 21:42:32 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 "csu-common.h" 44 45 void _libc_init(void) __attribute__((__constructor__, __used__)); 46 47 void __guard_setup(void); 48 void __libc_thr_init(void); 49 void __libc_atomic_init(void); 50 void __libc_atexit_init(void); 51 void __libc_env_init(void); 52 53 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 54 __dso_hidden void __libc_static_tls_setup(void); 55 #endif 56 57 #ifdef __weak_alias 58 __weak_alias(_dlauxinfo,___dlauxinfo) 59 static void *__libc_dlauxinfo; 60 61 void *___dlauxinfo(void) __pure; 62 __weakref_visible void * real_dlauxinfo(void) __weak_reference(_dlauxinfo); 63 64 void * 65 ___dlauxinfo(void) 66 { 67 return __libc_dlauxinfo; 68 } 69 #endif 70 71 static bool libc_initialised; 72 73 void _libc_init(void); 74 75 /* 76 * Declare as common symbol to allow new libc with older binaries to 77 * not trigger an undefined reference. 78 */ 79 struct ps_strings *__ps_strings __common; 80 char *__progname __common; 81 char **environ __common; 82 83 /* 84 * _libc_init is called twice. One call comes explicitly from crt0.o 85 * (for newer versions) and the other is via global constructor handling. 86 * 87 * In static binaries the explicit call is first; in dynamically linked 88 * binaries the global constructors of libc are called from ld.elf_so 89 * before crt0.o is reached. 90 * 91 * Note that __ps_strings is set by crt0.o. So in the dynamic case, it 92 * hasn't been set yet when we get here, and __libc_dlauxinfo is not 93 * (ever) assigned. But this is ok because __libc_dlauxinfo is only 94 * used in static binaries, because it's there to substitute for the 95 * dynamic linker. In static binaries __ps_strings will have been set 96 * up when we get here and we get a valid __libc_dlauxinfo. 97 * 98 * This code causes problems for Emacs because Emacs's undump 99 * mechanism saves the __ps_strings value from the startup execution; 100 * then running the resulting binary it gets here before crt0 has 101 * assigned the current execution's value to __ps_strings, and in an 102 * environment with ASLR this can cause the assignment of 103 * __libc_dlauxinfo to receive SIGSEGV. 104 */ 105 void __section(".text.startup") 106 _libc_init(void) 107 { 108 109 if (libc_initialised) 110 return; 111 112 libc_initialised = 1; 113 114 /* Only initialize _dlauxinfo for static binaries. */ 115 if (__ps_strings != NULL && real_dlauxinfo == ___dlauxinfo) 116 __libc_dlauxinfo = __ps_strings->ps_argvstr + 117 __ps_strings->ps_nargvstr + __ps_strings->ps_nenvstr + 2; 118 119 /* For -fstack-protector */ 120 __guard_setup(); 121 122 /* Atomic operations */ 123 __libc_atomic_init(); 124 125 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 126 /* Initialize TLS for statically linked programs. */ 127 __libc_static_tls_setup(); 128 #endif 129 130 /* Threads */ 131 __libc_thr_init(); 132 133 /* Initialize the atexit mutexes */ 134 __libc_atexit_init(); 135 136 /* Initialize environment memory RB tree. */ 137 __libc_env_init(); 138 } 139