linker.h revision d23736e4f228e46304b7cbc674a1d0094d73e0f5 
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_ERROR      0x00000002
76#define FLAG_EXE        0x00000004 // The main executable
77#define FLAG_LINKER     0x00000010 // The linker itself
78
79#define SOINFO_NAME_LEN 128
80
81struct soinfo {
82  char name[SOINFO_NAME_LEN];
83  const Elf32_Phdr* phdr;
84  int phnum;
85  unsigned entry;
86  unsigned base;
87  unsigned size;
88
89  int unused;  // DO NOT USE, maintained for compatibility.
90
91  unsigned* dynamic;
92
93  unsigned unused2; // DO NOT USE, maintained for compatibility
94  unsigned unused3; // DO NOT USE, maintained for compatibility
95
96  soinfo* next;
97  unsigned flags;
98
99  const char* strtab;
100  Elf32_Sym* symtab;
101
102  unsigned nbucket;
103  unsigned nchain;
104  unsigned* bucket;
105  unsigned* chain;
106
107  unsigned* plt_got;
108
109  Elf32_Rel* plt_rel;
110  unsigned plt_rel_count;
111
112  Elf32_Rel* rel;
113  unsigned rel_count;
114
115  unsigned* preinit_array;
116  unsigned preinit_array_count;
117
118  unsigned* init_array;
119  unsigned init_array_count;
120  unsigned* fini_array;
121  unsigned fini_array_count;
122
123  void (*init_func)();
124  void (*fini_func)();
125
126#if defined(ANDROID_ARM_LINKER)
127  // ARM EABI section used for stack unwinding.
128  unsigned* ARM_exidx;
129  unsigned ARM_exidx_count;
130#elif defined(ANDROID_MIPS_LINKER)
131#if 0
132  // Not yet.
133  unsigned* mips_pltgot
134#endif
135  unsigned mips_symtabno;
136  unsigned mips_local_gotno;
137  unsigned mips_gotsym;
138#endif
139
140  unsigned refcount;
141  struct link_map linkmap;
142
143  bool constructors_called;
144
145  // When you read a virtual address from the ELF file, add this
146  // value to get the corresponding address in the process' address space.
147  Elf32_Addr load_bias;
148
149  bool has_text_relocations;
150  bool has_DT_SYMBOLIC;
151
152  void CallConstructors();
153  void CallDestructors();
154  void CallPreInitConstructors();
155
156 private:
157  void CallArray(const char* array_name, unsigned* array, int count, bool reverse);
158  void CallFunction(const char* function_name, void (*function)());
159};
160
161extern soinfo libdl_info;
162
163#if defined(ANDROID_ARM_LINKER)
164
165// These aren't defined in <arch-arm/asm/elf.h>.
166#define R_ARM_REL32      3
167#define R_ARM_COPY       20
168#define R_ARM_GLOB_DAT   21
169#define R_ARM_JUMP_SLOT  22
170#define R_ARM_RELATIVE   23
171
172#elif defined(ANDROID_MIPS_LINKER)
173
174// These aren't defined in <arch-arm/mips/elf.h>.
175#define R_MIPS_JUMP_SLOT       127
176
177#define DT_MIPS_PLTGOT         0x70000032
178#define DT_MIPS_RWPLT          0x70000034
179
180#elif defined(ANDROID_X86_LINKER)
181
182// x86 has everything it needs in <arch-arm/x86/elf.h>.
183
184#endif /* ANDROID_*_LINKER */
185
186#ifndef DT_INIT_ARRAY
187#define DT_INIT_ARRAY      25
188#endif
189
190#ifndef DT_FINI_ARRAY
191#define DT_FINI_ARRAY      26
192#endif
193
194#ifndef DT_INIT_ARRAYSZ
195#define DT_INIT_ARRAYSZ    27
196#endif
197
198#ifndef DT_FINI_ARRAYSZ
199#define DT_FINI_ARRAYSZ    28
200#endif
201
202#ifndef DT_PREINIT_ARRAY
203#define DT_PREINIT_ARRAY   32
204#endif
205
206#ifndef DT_PREINIT_ARRAYSZ
207#define DT_PREINIT_ARRAYSZ 33
208#endif
209
210soinfo* do_dlopen(const char* name);
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