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 * 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") 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