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 <sys/time.h> 41 #include <sys/resource.h> 42 #include <unistd.h> 43 44 #include "atexit.h" 45 #include "private/bionic_auxv.h" 46 #include "private/bionic_ssp.h" 47 #include "private/KernelArgumentBlock.h" 48 #include "pthread_internal.h" 49 50 extern "C" abort_msg_t** __abort_message_ptr; 51 extern "C" unsigned __get_sp(void); 52 extern "C" int __system_properties_init(void); 53 54 // Not public, but well-known in the BSDs. 55 const char* __progname; 56 57 // Declared in <unistd.h>. 58 char** environ; 59 60 // Declared in <private/bionic_ssp.h>. 61 uintptr_t __stack_chk_guard = 0; 62 63 // Declared in <asm/page.h>. 64 unsigned int __page_size = PAGE_SIZE; 65 unsigned int __page_shift = PAGE_SHIFT; 66 67 static size_t get_stack_size() { 68 const size_t minimal_stack_size = 128 * 1024; 69 size_t stack_size = minimal_stack_size; 70 struct rlimit stack_limit; 71 int rlimit_result = getrlimit(RLIMIT_STACK, &stack_limit); 72 if ((rlimit_result == 0) && (stack_limit.rlim_cur != RLIM_INFINITY)) { 73 stack_size = stack_limit.rlim_cur; 74 stack_size = (stack_size & ~(PAGE_SIZE - 1)); 75 if (stack_size < minimal_stack_size) { 76 stack_size = minimal_stack_size; 77 } 78 } 79 return stack_size; 80 } 81 82 /* Init TLS for the initial thread. Called by the linker _before_ libc is mapped 83 * in memory. Beware: all writes to libc globals from this function will 84 * apply to linker-private copies and will not be visible from libc later on. 85 * 86 * Note: this function creates a pthread_internal_t for the initial thread and 87 * stores the pointer in TLS, but does not add it to pthread's gThreadList. This 88 * has to be done later from libc itself (see __libc_init_common). 89 * 90 * This function also stores a pointer to the kernel argument block in a TLS slot to be 91 * picked up by the libc constructor. 92 */ 93 void __libc_init_tls(KernelArgumentBlock& args) { 94 __libc_auxv = args.auxv; 95 96 uintptr_t stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE; 97 size_t stack_size = get_stack_size(); 98 uintptr_t stack_bottom = stack_top - stack_size; 99 100 static void* tls[BIONIC_TLS_SLOTS]; 101 static pthread_internal_t thread; 102 thread.tid = gettid(); 103 thread.tls = tls; 104 pthread_attr_init(&thread.attr); 105 pthread_attr_setstack(&thread.attr, (void*) stack_bottom, stack_size); 106 _init_thread(&thread, false); 107 __init_tls(&thread); 108 tls[TLS_SLOT_BIONIC_PREINIT] = &args; 109 } 110 111 void __libc_init_common(KernelArgumentBlock& args) { 112 // Initialize various globals. 113 environ = args.envp; 114 errno = 0; 115 __libc_auxv = args.auxv; 116 __progname = args.argv[0] ? args.argv[0] : "<unknown>"; 117 __abort_message_ptr = args.abort_message_ptr; 118 119 // AT_RANDOM is a pointer to 16 bytes of randomness on the stack. 120 __stack_chk_guard = *reinterpret_cast<uintptr_t*>(getauxval(AT_RANDOM)); 121 122 // Get the main thread from TLS and add it to the thread list. 123 pthread_internal_t* main_thread = __get_thread(); 124 main_thread->allocated_on_heap = false; 125 _pthread_internal_add(main_thread); 126 127 __system_properties_init(); // Requires 'environ'. 128 } 129 130 /* This function will be called during normal program termination 131 * to run the destructors that are listed in the .fini_array section 132 * of the executable, if any. 133 * 134 * 'fini_array' points to a list of function addresses. The first 135 * entry in the list has value -1, the last one has value 0. 136 */ 137 void __libc_fini(void* array) { 138 void** fini_array = reinterpret_cast<void**>(array); 139 const size_t minus1 = ~(size_t)0; /* ensure proper sign extension */ 140 141 /* Sanity check - first entry must be -1 */ 142 if (array == NULL || (size_t)fini_array[0] != minus1) { 143 return; 144 } 145 146 /* skip over it */ 147 fini_array += 1; 148 149 /* Count the number of destructors. */ 150 int count = 0; 151 while (fini_array[count] != NULL) { 152 ++count; 153 } 154 155 /* Now call each destructor in reverse order. */ 156 while (count > 0) { 157 void (*func)() = (void (*)()) fini_array[--count]; 158 159 /* Sanity check, any -1 in the list is ignored */ 160 if ((size_t)func == minus1) { 161 continue; 162 } 163 164 func(); 165 } 166 167 #ifndef LIBC_STATIC 168 { 169 extern void __libc_postfini(void) __attribute__((weak)); 170 if (__libc_postfini) { 171 __libc_postfini(); 172 } 173 } 174 #endif 175 } 176
