linker.h revision cade4c36e7c9c62db3f476a0f9cfc329bac9acb7 
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 <unistd.h>
33#include <sys/types.h>
34#include <elf.h>
35#include <sys/exec_elf.h>
36
37#include <link.h>
38
39// Returns the address of the page containing address 'x'.
40#define PAGE_START(x)  ((x) & PAGE_MASK)
41
42// Returns the offset of address 'x' in its page.
43#define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
44
45// Returns the address of the next page after address 'x', unless 'x' is
46// itself at the start of a page.
47#define PAGE_END(x)    PAGE_START((x) + (PAGE_SIZE-1))
48
49// Magic shared structures that GDB knows about.
50
51struct link_map {
52  uintptr_t l_addr;
53  char * l_name;
54  uintptr_t l_ld;
55  struct link_map * l_next;
56  struct link_map * l_prev;
57};
58
59// Values for r_debug->state
60enum {
61  RT_CONSISTENT,
62  RT_ADD,
63  RT_DELETE
64};
65
66struct r_debug {
67  int32_t r_version;
68  struct link_map* r_map;
69  void (*r_brk)(void);
70  int32_t r_state;
71  uintptr_t r_ldbase;
72};
73
74#define FLAG_LINKED     0x00000001
75#define FLAG_EXE        0x00000004 // The main executable
76#define FLAG_LINKER     0x00000010 // The linker itself
77
78#define SOINFO_NAME_LEN 128
79
80struct soinfo {
81  char name[SOINFO_NAME_LEN];
82  const Elf32_Phdr* phdr;
83  int phnum;
84  unsigned entry;
85  unsigned base;
86  unsigned size;
87
88  int unused;  // DO NOT USE, maintained for compatibility.
89
90  unsigned* dynamic;
91
92  unsigned unused2; // DO NOT USE, maintained for compatibility
93  unsigned unused3; // DO NOT USE, maintained for compatibility
94
95  soinfo* next;
96  unsigned flags;
97
98  const char* strtab;
99  Elf32_Sym* symtab;
100
101  unsigned nbucket;
102  unsigned nchain;
103  unsigned* bucket;
104  unsigned* chain;
105
106  unsigned* plt_got;
107
108  Elf32_Rel* plt_rel;
109  unsigned plt_rel_count;
110
111  Elf32_Rel* rel;
112  unsigned rel_count;
113
114  unsigned* preinit_array;
115  unsigned preinit_array_count;
116
117  unsigned* init_array;
118  unsigned init_array_count;
119  unsigned* fini_array;
120  unsigned fini_array_count;
121
122  void (*init_func)();
123  void (*fini_func)();
124
125#if defined(ANDROID_ARM_LINKER)
126  // ARM EABI section used for stack unwinding.
127  unsigned* ARM_exidx;
128  unsigned ARM_exidx_count;
129#elif defined(ANDROID_MIPS_LINKER)
130#if 0
131  // Not yet.
132  unsigned* mips_pltgot
133#endif
134  unsigned mips_symtabno;
135  unsigned mips_local_gotno;
136  unsigned mips_gotsym;
137#endif
138
139  unsigned refcount;
140  struct link_map linkmap;
141
142  bool constructors_called;
143
144  // When you read a virtual address from the ELF file, add this
145  // value to get the corresponding address in the process' address space.
146  Elf32_Addr load_bias;
147
148  bool has_text_relocations;
149  bool has_DT_SYMBOLIC;
150
151  void CallConstructors();
152  void CallDestructors();
153  void CallPreInitConstructors();
154
155 private:
156  void CallArray(const char* array_name, unsigned* array, int count, bool reverse);
157  void CallFunction(const char* function_name, void (*function)());
158};
159
160extern soinfo libdl_info;
161
162#if defined(ANDROID_ARM_LINKER)
163
164// These aren't defined in <arch-arm/asm/elf.h>.
165#define R_ARM_REL32      3
166#define R_ARM_COPY       20
167#define R_ARM_GLOB_DAT   21
168#define R_ARM_JUMP_SLOT  22
169#define R_ARM_RELATIVE   23
170
171#elif defined(ANDROID_MIPS_LINKER)
172
173// These aren't defined in <arch-arm/mips/elf.h>.
174#define R_MIPS_JUMP_SLOT       127
175
176#define DT_MIPS_PLTGOT         0x70000032
177#define DT_MIPS_RWPLT          0x70000034
178
179#elif defined(ANDROID_X86_LINKER)
180
181// x86 has everything it needs in <arch-arm/x86/elf.h>.
182
183#endif /* ANDROID_*_LINKER */
184
185#ifndef DT_INIT_ARRAY
186#define DT_INIT_ARRAY      25
187#endif
188
189#ifndef DT_FINI_ARRAY
190#define DT_FINI_ARRAY      26
191#endif
192
193#ifndef DT_INIT_ARRAYSZ
194#define DT_INIT_ARRAYSZ    27
195#endif
196
197#ifndef DT_FINI_ARRAYSZ
198#define DT_FINI_ARRAYSZ    28
199#endif
200
201#ifndef DT_PREINIT_ARRAY
202#define DT_PREINIT_ARRAY   32
203#endif
204
205#ifndef DT_PREINIT_ARRAYSZ
206#define DT_PREINIT_ARRAYSZ 33
207#endif
208
209void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
210soinfo* do_dlopen(const char* name, int flags);
211int do_dlclose(soinfo* si);
212
213Elf32_Sym* lookup(const char* name, soinfo** found, soinfo* start);
214soinfo* find_containing_library(const void* addr);
215const char* linker_get_error();
216
217Elf32_Sym* soinfo_find_symbol(soinfo* si, const void* addr);
218Elf32_Sym* soinfo_lookup(soinfo* si, const char* name);
219
220void debugger_init();
221extern "C" void notify_gdb_of_libraries();
222
223#endif
224