1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include "libc_init_common.h" 30 31 #include <asm/page.h> 32 #include <bionic_tls.h> 33 #include <elf.h> 34 #include <errno.h> 35 #include <stddef.h> 36 #include <stdint.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <sys/auxv.h> 40 #include <unistd.h> 41 42 #include "atexit.h" 43 #include "private/bionic_auxv.h" 44 #include "private/bionic_ssp.h" 45 #include "private/KernelArgumentBlock.h" 46 #include "pthread_internal.h" 47 48 extern "C" abort_msg_t** __abort_message_ptr; 49 extern "C" unsigned __get_sp(void); 50 extern "C" int __system_properties_init(void); 51 52 // Not public, but well-known in the BSDs. 53 const char* __progname; 54 55 // Declared in <unistd.h>. 56 char** environ; 57 58 // Declared in <private/bionic_ssp.h>. 59 uintptr_t __stack_chk_guard = 0; 60 61 // Declared in <asm/page.h>. 62 unsigned int __page_size = PAGE_SIZE; 63 unsigned int __page_shift = PAGE_SHIFT; 64 65 /* Init TLS for the initial thread. Called by the linker _before_ libc is mapped 66 * in memory. Beware: all writes to libc globals from this function will 67 * apply to linker-private copies and will not be visible from libc later on. 68 * 69 * Note: this function creates a pthread_internal_t for the initial thread and 70 * stores the pointer in TLS, but does not add it to pthread's gThreadList. This 71 * has to be done later from libc itself (see __libc_init_common). 72 * 73 * This function also stores a pointer to the kernel argument block in a TLS slot to be 74 * picked up by the libc constructor. 75 */ 76 void __libc_init_tls(KernelArgumentBlock& args) { 77 __libc_auxv = args.auxv; 78 79 unsigned stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE; 80 unsigned stack_size = 128 * 1024; 81 unsigned stack_bottom = stack_top - stack_size; 82 83 static void* tls[BIONIC_TLS_SLOTS]; 84 static pthread_internal_t thread; 85 thread.tid = gettid(); 86 thread.tls = tls; 87 pthread_attr_init(&thread.attr); 88 pthread_attr_setstack(&thread.attr, (void*) stack_bottom, stack_size); 89 _init_thread(&thread, false); 90 __init_tls(&thread); 91 tls[TLS_SLOT_BIONIC_PREINIT] = &args; 92 } 93 94 void __libc_init_common(KernelArgumentBlock& args) { 95 // Initialize various globals. 96 environ = args.envp; 97 errno = 0; 98 __libc_auxv = args.auxv; 99 __progname = args.argv[0] ? args.argv[0] : "<unknown>"; 100 __abort_message_ptr = args.abort_message_ptr; 101 102 // AT_RANDOM is a pointer to 16 bytes of randomness on the stack. 103 __stack_chk_guard = *reinterpret_cast<uintptr_t*>(getauxval(AT_RANDOM)); 104 105 // Get the main thread from TLS and add it to the thread list. 106 pthread_internal_t* main_thread = __get_thread(); 107 main_thread->allocated_on_heap = false; 108 _pthread_internal_add(main_thread); 109 110 __system_properties_init(); // Requires 'environ'. 111 } 112 113 /* This function will be called during normal program termination 114 * to run the destructors that are listed in the .fini_array section 115 * of the executable, if any. 116 * 117 * 'fini_array' points to a list of function addresses. The first 118 * entry in the list has value -1, the last one has value 0. 119 */ 120 void __libc_fini(void* array) { 121 void** fini_array = reinterpret_cast<void**>(array); 122 const size_t minus1 = ~(size_t)0; /* ensure proper sign extension */ 123 124 /* Sanity check - first entry must be -1 */ 125 if (array == NULL || (size_t)fini_array[0] != minus1) { 126 return; 127 } 128 129 /* skip over it */ 130 fini_array += 1; 131 132 /* Count the number of destructors. */ 133 int count = 0; 134 while (fini_array[count] != NULL) { 135 ++count; 136 } 137 138 /* Now call each destructor in reverse order. */ 139 while (count > 0) { 140 void (*func)() = (void (*)()) fini_array[--count]; 141 142 /* Sanity check, any -1 in the list is ignored */ 143 if ((size_t)func == minus1) { 144 continue; 145 } 146 147 func(); 148 } 149 150 #ifndef LIBC_STATIC 151 { 152 extern void __libc_postfini(void) __attribute__((weak)); 153 if (__libc_postfini) { 154 __libc_postfini(); 155 } 156 } 157 #endif 158 } 159