linker.h revision 650be4e584eeab3591b9e273bfd6d169eea60853 
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/debug_format.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 {
61  uintptr_t l_addr;
62  char*  l_name;
63  uintptr_t l_ld;
64  struct link_map* l_next;
65  struct link_map* 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  struct link_map* 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
89struct soinfo {
90  char name[SOINFO_NAME_LEN];
91  const Elf32_Phdr* phdr;
92  int phnum;
93  unsigned entry;
94  unsigned base;
95  unsigned size;
96
97  int unused;  // DO NOT USE, maintained for compatibility.
98
99  Elf32_Dyn* dynamic;
100
101  unsigned unused2; // DO NOT USE, maintained for compatibility
102  unsigned unused3; // DO NOT USE, maintained for compatibility
103
104  soinfo* next;
105  unsigned flags;
106
107  const char* strtab;
108  Elf32_Sym* symtab;
109
110  unsigned nbucket;
111  unsigned nchain;
112  unsigned* bucket;
113  unsigned* chain;
114
115  unsigned* plt_got;
116
117  Elf32_Rel* plt_rel;
118  unsigned plt_rel_count;
119
120  Elf32_Rel* rel;
121  unsigned rel_count;
122
123  unsigned* preinit_array;
124  unsigned preinit_array_count;
125
126  unsigned* init_array;
127  unsigned init_array_count;
128  unsigned* fini_array;
129  unsigned fini_array_count;
130
131  void (*init_func)();
132  void (*fini_func)();
133
134#if defined(ANDROID_ARM_LINKER)
135  // ARM EABI section used for stack unwinding.
136  unsigned* ARM_exidx;
137  unsigned ARM_exidx_count;
138#elif defined(ANDROID_MIPS_LINKER)
139  unsigned mips_symtabno;
140  unsigned mips_local_gotno;
141  unsigned mips_gotsym;
142#endif
143
144  unsigned refcount;
145  struct link_map linkmap;
146
147  bool constructors_called;
148
149  // When you read a virtual address from the ELF file, add this
150  // value to get the corresponding address in the process' address space.
151  Elf32_Addr load_bias;
152
153  bool has_text_relocations;
154  bool has_DT_SYMBOLIC;
155
156  void CallConstructors();
157  void CallDestructors();
158  void CallPreInitConstructors();
159
160 private:
161  void CallArray(const char* array_name, unsigned* array, int count, bool reverse);
162  void CallFunction(const char* function_name, void (*function)());
163};
164
165extern soinfo libdl_info;
166
167// These aren't defined in <sys/exec_elf.h>.
168#ifndef DT_PREINIT_ARRAY
169#define DT_PREINIT_ARRAY   32
170#endif
171#ifndef DT_PREINIT_ARRAYSZ
172#define DT_PREINIT_ARRAYSZ 33
173#endif
174
175void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
176soinfo* do_dlopen(const char* name, int flags);
177int do_dlclose(soinfo* si);
178
179Elf32_Sym* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
180soinfo* find_containing_library(const void* addr);
181
182Elf32_Sym* dladdr_find_symbol(soinfo* si, const void* addr);
183Elf32_Sym* dlsym_handle_lookup(soinfo* si, const char* name);
184
185void debuggerd_init();
186extern "C" void notify_gdb_of_libraries();
187
188char* linker_get_error_buffer();
189size_t linker_get_error_buffer_size();
190
191#endif
192