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 <inttypes.h> 34 #include <link.h> 35 #include <unistd.h> 36 #include <android/dlext.h> 37 #include <sys/stat.h> 38 39 #include "private/libc_logging.h" 40 #include "linked_list.h" 41 42 #define DL_ERR(fmt, x...) \ 43 do { \ 44 __libc_format_buffer(linker_get_error_buffer(), linker_get_error_buffer_size(), fmt, ##x); \ 45 /* If LD_DEBUG is set high enough, log every dlerror(3) message. */ \ 46 DEBUG("%s\n", linker_get_error_buffer()); \ 47 } while (false) 48 49 #define DL_WARN(fmt, x...) \ 50 do { \ 51 __libc_format_log(ANDROID_LOG_WARN, "linker", fmt, ##x); \ 52 __libc_format_fd(2, "WARNING: linker: "); \ 53 __libc_format_fd(2, fmt, ##x); \ 54 __libc_format_fd(2, "\n"); \ 55 } while (false) 56 57 #if defined(__LP64__) 58 #define ELFW(what) ELF64_ ## what 59 #else 60 #define ELFW(what) ELF32_ ## what 61 #endif 62 63 // mips64 interprets Elf64_Rel structures' r_info field differently. 64 // bionic (like other C libraries) has macros that assume regular ELF files, 65 // but the dynamic linker needs to be able to load mips64 ELF files. 66 #if defined(__mips__) && defined(__LP64__) 67 #undef ELF64_R_SYM 68 #undef ELF64_R_TYPE 69 #undef ELF64_R_INFO 70 #define ELF64_R_SYM(info) (((info) >> 0) & 0xffffffff) 71 #define ELF64_R_SSYM(info) (((info) >> 32) & 0xff) 72 #define ELF64_R_TYPE3(info) (((info) >> 40) & 0xff) 73 #define ELF64_R_TYPE2(info) (((info) >> 48) & 0xff) 74 #define ELF64_R_TYPE(info) (((info) >> 56) & 0xff) 75 #endif 76 77 // Returns the address of the page containing address 'x'. 78 #define PAGE_START(x) ((x) & PAGE_MASK) 79 80 // Returns the offset of address 'x' in its page. 81 #define PAGE_OFFSET(x) ((x) & ~PAGE_MASK) 82 83 // Returns the address of the next page after address 'x', unless 'x' is 84 // itself at the start of a page. 85 #define PAGE_END(x) PAGE_START((x) + (PAGE_SIZE-1)) 86 87 #define FLAG_LINKED 0x00000001 88 #define FLAG_EXE 0x00000004 // The main executable 89 #define FLAG_LINKER 0x00000010 // The linker itself 90 #define FLAG_NEW_SOINFO 0x40000000 // new soinfo format 91 92 #define SOINFO_VERSION 0 93 94 #define SOINFO_NAME_LEN 128 95 96 typedef void (*linker_function_t)(); 97 98 // Android uses RELA for aarch64 and x86_64. mips64 still uses REL. 99 #if defined(__aarch64__) || defined(__x86_64__) 100 #define USE_RELA 1 101 #endif 102 103 struct soinfo; 104 105 class SoinfoListAllocator { 106 public: 107 static LinkedListEntry<soinfo>* alloc(); 108 static void free(LinkedListEntry<soinfo>* entry); 109 private: 110 // unconstructable 111 DISALLOW_IMPLICIT_CONSTRUCTORS(SoinfoListAllocator); 112 }; 113 114 struct soinfo { 115 public: 116 typedef LinkedList<soinfo, SoinfoListAllocator> soinfo_list_t; 117 public: 118 char name[SOINFO_NAME_LEN]; 119 const ElfW(Phdr)* phdr; 120 size_t phnum; 121 ElfW(Addr) entry; 122 ElfW(Addr) base; 123 size_t size; 124 125 #ifndef __LP64__ 126 uint32_t unused1; // DO NOT USE, maintained for compatibility. 127 #endif 128 129 ElfW(Dyn)* dynamic; 130 131 #ifndef __LP64__ 132 uint32_t unused2; // DO NOT USE, maintained for compatibility 133 uint32_t unused3; // DO NOT USE, maintained for compatibility 134 #endif 135 136 soinfo* next; 137 unsigned flags; 138 139 private: 140 const char* strtab; 141 public: 142 ElfW(Sym)* symtab; 143 144 size_t nbucket; 145 size_t nchain; 146 unsigned* bucket; 147 unsigned* chain; 148 149 #if defined(__mips__) || !defined(__LP64__) 150 // This is only used by mips and mips64, but needs to be here for 151 // all 32-bit architectures to preserve binary compatibility. 152 ElfW(Addr)** plt_got; 153 #endif 154 155 #if defined(USE_RELA) 156 ElfW(Rela)* plt_rela; 157 size_t plt_rela_count; 158 159 ElfW(Rela)* rela; 160 size_t rela_count; 161 #else 162 ElfW(Rel)* plt_rel; 163 size_t plt_rel_count; 164 165 ElfW(Rel)* rel; 166 size_t rel_count; 167 #endif 168 169 linker_function_t* preinit_array; 170 size_t preinit_array_count; 171 172 linker_function_t* init_array; 173 size_t init_array_count; 174 linker_function_t* fini_array; 175 size_t fini_array_count; 176 177 linker_function_t init_func; 178 linker_function_t fini_func; 179 180 #if defined(__arm__) 181 // ARM EABI section used for stack unwinding. 182 unsigned* ARM_exidx; 183 size_t ARM_exidx_count; 184 #elif defined(__mips__) 185 unsigned mips_symtabno; 186 unsigned mips_local_gotno; 187 unsigned mips_gotsym; 188 #endif 189 190 size_t ref_count; 191 link_map link_map_head; 192 193 bool constructors_called; 194 195 // When you read a virtual address from the ELF file, add this 196 // value to get the corresponding address in the process' address space. 197 ElfW(Addr) load_bias; 198 199 #if !defined(__LP64__) 200 bool has_text_relocations; 201 #endif 202 bool has_DT_SYMBOLIC; 203 204 soinfo(const char* name, const struct stat* file_stat, off64_t file_offset); 205 206 void CallConstructors(); 207 void CallDestructors(); 208 void CallPreInitConstructors(); 209 bool PrelinkImage(); 210 bool LinkImage(const android_dlextinfo* extinfo); 211 212 void add_child(soinfo* child); 213 void remove_all_links(); 214 215 ino_t get_st_ino(); 216 dev_t get_st_dev(); 217 off64_t get_file_offset(); 218 219 soinfo_list_t& get_children(); 220 soinfo_list_t& get_parents(); 221 222 ElfW(Addr) resolve_symbol_address(ElfW(Sym)* s); 223 224 const char* get_string(ElfW(Word) index) const; 225 226 bool inline has_min_version(uint32_t min_version) const { 227 return (flags & FLAG_NEW_SOINFO) != 0 && version >= min_version; 228 } 229 private: 230 void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse); 231 void CallFunction(const char* function_name, linker_function_t function); 232 #if defined(USE_RELA) 233 int Relocate(ElfW(Rela)* rela, unsigned count); 234 #else 235 int Relocate(ElfW(Rel)* rel, unsigned count); 236 #endif 237 238 private: 239 // This part of the structure is only available 240 // when FLAG_NEW_SOINFO is set in this->flags. 241 uint32_t version; 242 243 // version >= 0 244 dev_t st_dev; 245 ino_t st_ino; 246 247 // dependency graph 248 soinfo_list_t children; 249 soinfo_list_t parents; 250 251 // version >= 1 252 off64_t file_offset; 253 int rtld_flags; 254 size_t strtab_size; 255 256 friend soinfo* get_libdl_info(); 257 }; 258 259 extern soinfo* get_libdl_info(); 260 261 void do_android_get_LD_LIBRARY_PATH(char*, size_t); 262 void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path); 263 soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo); 264 void do_dlclose(soinfo* si); 265 266 ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start); 267 soinfo* find_containing_library(const void* addr); 268 269 ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr); 270 ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name); 271 272 void debuggerd_init(); 273 extern "C" abort_msg_t* g_abort_message; 274 extern "C" void notify_gdb_of_libraries(); 275 276 char* linker_get_error_buffer(); 277 size_t linker_get_error_buffer_size(); 278 279 #endif 280
