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 */
29 #ifndef _LINKER_H_
30 #define _LINKER_H_
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>
39 #include "private/libc_logging.h"
40 #include "linked_list.h"
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)
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)
57 #if defined(__LP64__)
58 #define ELFW(what) ELF64_ ## what
59 #else
60 #define ELFW(what) ELF32_ ## what
61 #endif
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
77 // Returns the address of the page containing address 'x'.
78 #define PAGE_START(x) ((x) & PAGE_MASK)
80 // Returns the offset of address 'x' in its page.
81 #define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
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))
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
92 #define SOINFO_VERSION 1
94 #define SOINFO_NAME_LEN 128
96 typedef void (*linker_function_t)();
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
103 struct soinfo;
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 };
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;
125 #ifndef __LP64__
126 uint32_t unused1; // DO NOT USE, maintained for compatibility.
127 #endif
129 ElfW(Dyn)* dynamic;
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
136 soinfo* next;
137 unsigned flags;
139 private:
140 const char* strtab;
141 public:
142 ElfW(Sym)* symtab;
144 size_t nbucket;
145 size_t nchain;
146 unsigned* bucket;
147 unsigned* chain;
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
155 #if defined(USE_RELA)
156 ElfW(Rela)* plt_rela;
157 size_t plt_rela_count;
159 ElfW(Rela)* rela;
160 size_t rela_count;
161 #else
162 ElfW(Rel)* plt_rel;
163 size_t plt_rel_count;
165 ElfW(Rel)* rel;
166 size_t rel_count;
167 #endif
169 linker_function_t* preinit_array;
170 size_t preinit_array_count;
172 linker_function_t* init_array;
173 size_t init_array_count;
174 linker_function_t* fini_array;
175 size_t fini_array_count;
177 linker_function_t init_func;
178 linker_function_t fini_func;
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
190 size_t ref_count;
191 link_map link_map_head;
193 bool constructors_called;
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;
199 #if !defined(__LP64__)
200 bool has_text_relocations;
201 #endif
202 bool has_DT_SYMBOLIC;
204 soinfo(const char* name, const struct stat* file_stat, int rtld_flags);
206 void CallConstructors();
207 void CallDestructors();
208 void CallPreInitConstructors();
209 bool PrelinkImage();
210 bool LinkImage(const android_dlextinfo* extinfo);
212 void add_child(soinfo* child);
213 void remove_all_links();
215 void set_st_dev(dev_t st_dev);
216 void set_st_ino(ino_t st_ino);
217 ino_t get_st_ino();
218 dev_t get_st_dev();
220 int get_rtld_flags();
222 soinfo_list_t& get_children();
223 soinfo_list_t& get_parents();
225 ElfW(Addr) resolve_symbol_address(ElfW(Sym)* s);
227 const char* get_string(ElfW(Word) index) const;
229 bool inline has_min_version(uint32_t min_version) const {
230 return (flags & FLAG_NEW_SOINFO) != 0 && version >= min_version;
231 }
232 private:
233 void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse);
234 void CallFunction(const char* function_name, linker_function_t function);
235 #if defined(USE_RELA)
236 int Relocate(ElfW(Rela)* rela, unsigned count);
237 #else
238 int Relocate(ElfW(Rel)* rel, unsigned count);
239 #endif
241 private:
242 // This part of the structure is only available
243 // when FLAG_NEW_SOINFO is set in this->flags.
244 uint32_t version;
246 // version >= 0
247 dev_t st_dev;
248 ino_t st_ino;
250 // dependency graph
251 soinfo_list_t children;
252 soinfo_list_t parents;
254 // version >= 1
255 int rtld_flags;
256 size_t strtab_size;
258 friend soinfo* get_libdl_info();
259 };
261 extern soinfo* get_libdl_info();
263 void do_android_get_LD_LIBRARY_PATH(char*, size_t);
264 void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
265 soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo);
266 void do_dlclose(soinfo* si);
268 ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
269 soinfo* find_containing_library(const void* addr);
271 ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr);
272 ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name);
274 void debuggerd_init();
275 extern "C" abort_msg_t* g_abort_message;
276 extern "C" void notify_gdb_of_libraries();
278 char* linker_get_error_buffer();
279 size_t linker_get_error_buffer_size();
281 #endif