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 <link.h>
34 #include <unistd.h>
35 #include <android/dlext.h>
36 #include <sys/stat.h>
38 #include "private/libc_logging.h"
39 #include "linked_list.h"
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)
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)
56 #if defined(__LP64__)
57 #define ELFW(what) ELF64_ ## what
58 #else
59 #define ELFW(what) ELF32_ ## what
60 #endif
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
76 // Returns the address of the page containing address 'x'.
77 #define PAGE_START(x) ((x) & PAGE_MASK)
79 // Returns the offset of address 'x' in its page.
80 #define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
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))
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
91 #define SOINFO_NAME_LEN 128
93 typedef void (*linker_function_t)();
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
100 struct soinfo;
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 };
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;
122 #ifndef __LP64__
123 uint32_t unused1; // DO NOT USE, maintained for compatibility.
124 #endif
126 ElfW(Dyn)* dynamic;
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
133 soinfo* next;
134 unsigned flags;
136 const char* strtab;
137 ElfW(Sym)* symtab;
139 size_t nbucket;
140 size_t nchain;
141 unsigned* bucket;
142 unsigned* chain;
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
150 #if defined(USE_RELA)
151 ElfW(Rela)* plt_rela;
152 size_t plt_rela_count;
154 ElfW(Rela)* rela;
155 size_t rela_count;
156 #else
157 ElfW(Rel)* plt_rel;
158 size_t plt_rel_count;
160 ElfW(Rel)* rel;
161 size_t rel_count;
162 #endif
164 linker_function_t* preinit_array;
165 size_t preinit_array_count;
167 linker_function_t* init_array;
168 size_t init_array_count;
169 linker_function_t* fini_array;
170 size_t fini_array_count;
172 linker_function_t init_func;
173 linker_function_t fini_func;
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
185 size_t ref_count;
186 link_map link_map_head;
188 bool constructors_called;
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;
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();
202 void add_child(soinfo* child);
203 void remove_all_links();
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();
210 soinfo_list_t& get_children();
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);
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;
221 dev_t st_dev;
222 ino_t st_ino;
224 // dependency graph
225 soinfo_list_t children;
226 soinfo_list_t parents;
228 };
230 extern soinfo* get_libdl_info();
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);
237 ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
238 soinfo* find_containing_library(const void* addr);
240 ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr);
241 ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name);
243 void debuggerd_init();
244 extern "C" abort_msg_t* g_abort_message;
245 extern "C" void notify_gdb_of_libraries();
247 char* linker_get_error_buffer();
248 size_t linker_get_error_buffer_size();
250 #endif