linker.h revision 0d787c1fa18c6a1f29ef9840e28a68cf077be1de 
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#include "private/libc_logging.h"
40
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(0)
47
48// Returns the address of the page containing address 'x'.
49#define PAGE_START(x)  ((x) & PAGE_MASK)
50
51// Returns the offset of address 'x' in its page.
52#define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
53
54// Returns the address of the next page after address 'x', unless 'x' is
55// itself at the start of a page.
56#define PAGE_END(x)    PAGE_START((x) + (PAGE_SIZE-1))
57
58// Magic shared structures that GDB knows about.
59
60struct link_map_t {
61  uintptr_t l_addr;
62  char*  l_name;
63  uintptr_t l_ld;
64  link_map_t* l_next;
65  link_map_t* l_prev;
66};
67
68// Values for r_debug->state
69enum {
70  RT_CONSISTENT,
71  RT_ADD,
72  RT_DELETE
73};
74
75struct r_debug {
76  int32_t r_version;
77  link_map_t* r_map;
78  void (*r_brk)(void);
79  int32_t r_state;
80  uintptr_t r_ldbase;
81};
82
83#define FLAG_LINKED     0x00000001
84#define FLAG_EXE        0x00000004 // The main executable
85#define FLAG_LINKER     0x00000010 // The linker itself
86
87#define SOINFO_NAME_LEN 128
88
89typedef void (*linker_function_t)();
90
91struct soinfo {
92 public:
93  char name[SOINFO_NAME_LEN];
94  const Elf32_Phdr* phdr;
95  size_t phnum;
96  Elf32_Addr entry;
97  Elf32_Addr base;
98  unsigned size;
99
100  uint32_t unused1;  // DO NOT USE, maintained for compatibility.
101
102  Elf32_Dyn* dynamic;
103
104  uint32_t unused2; // DO NOT USE, maintained for compatibility
105  uint32_t unused3; // DO NOT USE, maintained for compatibility
106
107  soinfo* next;
108  unsigned flags;
109
110  const char* strtab;
111  Elf32_Sym* symtab;
112
113  size_t nbucket;
114  size_t nchain;
115  unsigned* bucket;
116  unsigned* chain;
117
118  unsigned* plt_got;
119
120  Elf32_Rel* plt_rel;
121  size_t plt_rel_count;
122
123  Elf32_Rel* rel;
124  size_t rel_count;
125
126  linker_function_t* preinit_array;
127  size_t preinit_array_count;
128
129  linker_function_t* init_array;
130  size_t init_array_count;
131  linker_function_t* fini_array;
132  size_t fini_array_count;
133
134  linker_function_t init_func;
135  linker_function_t fini_func;
136
137#if defined(ANDROID_ARM_LINKER)
138  // ARM EABI section used for stack unwinding.
139  unsigned* ARM_exidx;
140  size_t ARM_exidx_count;
141#elif defined(ANDROID_MIPS_LINKER)
142  unsigned mips_symtabno;
143  unsigned mips_local_gotno;
144  unsigned mips_gotsym;
145#endif
146
147  size_t ref_count;
148  link_map_t link_map;
149
150  bool constructors_called;
151
152  // When you read a virtual address from the ELF file, add this
153  // value to get the corresponding address in the process' address space.
154  Elf32_Addr load_bias;
155
156  bool has_text_relocations;
157  bool has_DT_SYMBOLIC;
158
159  void CallConstructors();
160  void CallDestructors();
161  void CallPreInitConstructors();
162
163 private:
164  void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse);
165  void CallFunction(const char* function_name, linker_function_t function);
166};
167
168extern soinfo libdl_info;
169
170// These aren't defined in <sys/exec_elf.h>.
171#ifndef DT_PREINIT_ARRAY
172#define DT_PREINIT_ARRAY   32
173#endif
174#ifndef DT_PREINIT_ARRAYSZ
175#define DT_PREINIT_ARRAYSZ 33
176#endif
177
178void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
179soinfo* do_dlopen(const char* name, int flags);
180int do_dlclose(soinfo* si);
181
182Elf32_Sym* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
183soinfo* find_containing_library(const void* addr);
184
185Elf32_Sym* dladdr_find_symbol(soinfo* si, const void* addr);
186Elf32_Sym* dlsym_handle_lookup(soinfo* si, const char* name);
187
188void debuggerd_init();
189extern "C" abort_msg_t* gAbortMessage;
190extern "C" void notify_gdb_of_libraries();
191
192char* linker_get_error_buffer();
193size_t linker_get_error_buffer_size();
194
195#endif
196