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 #ifndef _LINKER_H_ 30 #define _LINKER_H_ 31 32 #include <elf.h> 33 #include <link.h> 34 #include <unistd.h> 35 #include <android/dlext.h> 36 #include <sys/stat.h> 37 38 #include "private/libc_logging.h" 39 #include "linked_list.h" 40 41 #define DL_ERR(fmt, x...) \ 42 do { \ 43 __libc_format_buffer(linker_get_error_buffer(), linker_get_error_buffer_size(), fmt, ##x); \ 44 /* If LD_DEBUG is set high enough, log every dlerror(3) message. */ \ 45 DEBUG("%s\n", linker_get_error_buffer()); \ 46 } while (false) 47 48 #define DL_WARN(fmt, x...) \ 49 do { \ 50 __libc_format_log(ANDROID_LOG_WARN, "linker", fmt, ##x); \ 51 __libc_format_fd(2, "WARNING: linker: "); \ 52 __libc_format_fd(2, fmt, ##x); \ 53 __libc_format_fd(2, "\n"); \ 54 } while (false) 55 56 #if defined(__LP64__) 57 #define ELFW(what) ELF64_ ## what 58 #else 59 #define ELFW(what) ELF32_ ## what 60 #endif 61 62 // mips64 interprets Elf64_Rel structures' r_info field differently. 63 // bionic (like other C libraries) has macros that assume regular ELF files, 64 // but the dynamic linker needs to be able to load mips64 ELF files. 65 #if defined(__mips__) && defined(__LP64__) 66 #undef ELF64_R_SYM 67 #undef ELF64_R_TYPE 68 #undef ELF64_R_INFO 69 #define ELF64_R_SYM(info) (((info) >> 0) & 0xffffffff) 70 #define ELF64_R_SSYM(info) (((info) >> 32) & 0xff) 71 #define ELF64_R_TYPE3(info) (((info) >> 40) & 0xff) 72 #define ELF64_R_TYPE2(info) (((info) >> 48) & 0xff) 73 #define ELF64_R_TYPE(info) (((info) >> 56) & 0xff) 74 #endif 75 76 // Returns the address of the page containing address 'x'. 77 #define PAGE_START(x) ((x) & PAGE_MASK) 78 79 // Returns the offset of address 'x' in its page. 80 #define PAGE_OFFSET(x) ((x) & ~PAGE_MASK) 81 82 // Returns the address of the next page after address 'x', unless 'x' is 83 // itself at the start of a page. 84 #define PAGE_END(x) PAGE_START((x) + (PAGE_SIZE-1)) 85 86 #define FLAG_LINKED 0x00000001 87 #define FLAG_EXE 0x00000004 // The main executable 88 #define FLAG_LINKER 0x00000010 // The linker itself 89 #define FLAG_NEW_SOINFO 0x40000000 // new soinfo format 90 91 #define SOINFO_NAME_LEN 128 92 93 typedef void (*linker_function_t)(); 94 95 // Android uses RELA for aarch64 and x86_64. mips64 still uses REL. 96 #if defined(__aarch64__) || defined(__x86_64__) 97 #define USE_RELA 1 98 #endif 99 100 struct soinfo; 101 102 class SoinfoListAllocator { 103 public: 104 static LinkedListEntry<soinfo>* alloc(); 105 static void free(LinkedListEntry<soinfo>* entry); 106 private: 107 // unconstructable 108 DISALLOW_IMPLICIT_CONSTRUCTORS(SoinfoListAllocator); 109 }; 110 111 struct soinfo { 112 public: 113 typedef LinkedList<soinfo, SoinfoListAllocator> soinfo_list_t; 114 public: 115 char name[SOINFO_NAME_LEN]; 116 const ElfW(Phdr)* phdr; 117 size_t phnum; 118 ElfW(Addr) entry; 119 ElfW(Addr) base; 120 size_t size; 121 122 #ifndef __LP64__ 123 uint32_t unused1; // DO NOT USE, maintained for compatibility. 124 #endif 125 126 ElfW(Dyn)* dynamic; 127 128 #ifndef __LP64__ 129 uint32_t unused2; // DO NOT USE, maintained for compatibility 130 uint32_t unused3; // DO NOT USE, maintained for compatibility 131 #endif 132 133 soinfo* next; 134 unsigned flags; 135 136 const char* strtab; 137 ElfW(Sym)* symtab; 138 139 size_t nbucket; 140 size_t nchain; 141 unsigned* bucket; 142 unsigned* chain; 143 144 #if defined(__mips__) || !defined(__LP64__) 145 // This is only used by mips and mips64, but needs to be here for 146 // all 32-bit architectures to preserve binary compatibility. 147 ElfW(Addr)** plt_got; 148 #endif 149 150 #if defined(USE_RELA) 151 ElfW(Rela)* plt_rela; 152 size_t plt_rela_count; 153 154 ElfW(Rela)* rela; 155 size_t rela_count; 156 #else 157 ElfW(Rel)* plt_rel; 158 size_t plt_rel_count; 159 160 ElfW(Rel)* rel; 161 size_t rel_count; 162 #endif 163 164 linker_function_t* preinit_array; 165 size_t preinit_array_count; 166 167 linker_function_t* init_array; 168 size_t init_array_count; 169 linker_function_t* fini_array; 170 size_t fini_array_count; 171 172 linker_function_t init_func; 173 linker_function_t fini_func; 174 175 #if defined(__arm__) 176 // ARM EABI section used for stack unwinding. 177 unsigned* ARM_exidx; 178 size_t ARM_exidx_count; 179 #elif defined(__mips__) 180 unsigned mips_symtabno; 181 unsigned mips_local_gotno; 182 unsigned mips_gotsym; 183 #endif 184 185 size_t ref_count; 186 link_map link_map_head; 187 188 bool constructors_called; 189 190 // When you read a virtual address from the ELF file, add this 191 // value to get the corresponding address in the process' address space. 192 ElfW(Addr) load_bias; 193 194 #if !defined(__LP64__) 195 bool has_text_relocations; 196 #endif 197 bool has_DT_SYMBOLIC; 198 void CallConstructors(); 199 void CallDestructors(); 200 void CallPreInitConstructors(); 201 202 void add_child(soinfo* child); 203 void remove_all_links(); 204 205 void set_st_dev(dev_t st_dev); 206 void set_st_ino(ino_t st_ino); 207 ino_t get_st_ino(); 208 dev_t get_st_dev(); 209 210 soinfo_list_t& get_children(); 211 212 private: 213 void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse); 214 void CallFunction(const char* function_name, linker_function_t function); 215 216 private: 217 // This part of the structure is only available 218 // when FLAG_NEW_SOINFO is set in this->flags. 219 unsigned int version; 220 221 dev_t st_dev; 222 ino_t st_ino; 223 224 // dependency graph 225 soinfo_list_t children; 226 soinfo_list_t parents; 227 228 }; 229 230 extern soinfo* get_libdl_info(); 231 232 void do_android_get_LD_LIBRARY_PATH(char*, size_t); 233 void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path); 234 soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo); 235 void do_dlclose(soinfo* si); 236 237 ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start); 238 soinfo* find_containing_library(const void* addr); 239 240 ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr); 241 ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name); 242 243 void debuggerd_init(); 244 extern "C" abort_msg_t* g_abort_message; 245 extern "C" void notify_gdb_of_libraries(); 246 247 char* linker_get_error_buffer(); 248 size_t linker_get_error_buffer_size(); 249 250 #endif 251
