linker.h revision c620059479c47a78d57086d73726c9adc2f337ad 
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 (false)
47
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)
55
56
57// Returns the address of the page containing address 'x'.
58#define PAGE_START(x)  ((x) & PAGE_MASK)
59
60// Returns the offset of address 'x' in its page.
61#define PAGE_OFFSET(x) ((x) & ~PAGE_MASK)
62
63// Returns the address of the next page after address 'x', unless 'x' is
64// itself at the start of a page.
65#define PAGE_END(x)    PAGE_START((x) + (PAGE_SIZE-1))
66
67// Magic shared structures that GDB knows about.
68
69struct link_map_t {
70  uintptr_t l_addr;
71  char*  l_name;
72  uintptr_t l_ld;
73  link_map_t* l_next;
74  link_map_t* l_prev;
75};
76
77// Values for r_debug->state
78enum {
79  RT_CONSISTENT,
80  RT_ADD,
81  RT_DELETE
82};
83
84struct r_debug {
85  int32_t r_version;
86  link_map_t* r_map;
87  void (*r_brk)(void);
88  int32_t r_state;
89  uintptr_t r_ldbase;
90};
91
92#define FLAG_LINKED     0x00000001
93#define FLAG_EXE        0x00000004 // The main executable
94#define FLAG_LINKER     0x00000010 // The linker itself
95
96#define SOINFO_NAME_LEN 128
97
98typedef void (*linker_function_t)();
99
100struct soinfo {
101 public:
102  char name[SOINFO_NAME_LEN];
103  const Elf_Phdr* phdr;
104  size_t phnum;
105  Elf_Addr entry;
106  Elf_Addr base;
107  unsigned size;
108
109#ifndef __LP64__
110  uint32_t unused1;  // DO NOT USE, maintained for compatibility.
111#endif
112
113  Elf_Dyn* dynamic;
114
115#ifndef __LP64__
116  uint32_t unused2; // DO NOT USE, maintained for compatibility
117  uint32_t unused3; // DO NOT USE, maintained for compatibility
118#endif
119
120  soinfo* next;
121  unsigned flags;
122
123  const char* strtab;
124  Elf_Sym* symtab;
125
126  size_t nbucket;
127  size_t nchain;
128  unsigned* bucket;
129  unsigned* chain;
130
131  unsigned* plt_got;
132
133  Elf_Rel* plt_rel;
134  size_t plt_rel_count;
135
136  Elf_Rel* rel;
137  size_t rel_count;
138
139  linker_function_t* preinit_array;
140  size_t preinit_array_count;
141
142  linker_function_t* init_array;
143  size_t init_array_count;
144  linker_function_t* fini_array;
145  size_t fini_array_count;
146
147  linker_function_t init_func;
148  linker_function_t fini_func;
149
150#if defined(ANDROID_ARM_LINKER)
151  // ARM EABI section used for stack unwinding.
152  unsigned* ARM_exidx;
153  size_t ARM_exidx_count;
154#elif defined(ANDROID_MIPS_LINKER)
155  unsigned mips_symtabno;
156  unsigned mips_local_gotno;
157  unsigned mips_gotsym;
158#endif
159
160  size_t ref_count;
161  link_map_t link_map;
162
163  bool constructors_called;
164
165  // When you read a virtual address from the ELF file, add this
166  // value to get the corresponding address in the process' address space.
167  Elf_Addr load_bias;
168
169  bool has_text_relocations;
170  bool has_DT_SYMBOLIC;
171
172  void CallConstructors();
173  void CallDestructors();
174  void CallPreInitConstructors();
175
176 private:
177  void CallArray(const char* array_name, linker_function_t* functions, size_t count, bool reverse);
178  void CallFunction(const char* function_name, linker_function_t function);
179};
180
181extern soinfo libdl_info;
182
183// These aren't defined in <sys/exec_elf.h>.
184#ifndef DT_PREINIT_ARRAY
185#define DT_PREINIT_ARRAY   32
186#endif
187#ifndef DT_PREINIT_ARRAYSZ
188#define DT_PREINIT_ARRAYSZ 33
189#endif
190
191void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
192soinfo* do_dlopen(const char* name, int flags);
193int do_dlclose(soinfo* si);
194
195Elf_Sym* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
196soinfo* find_containing_library(const void* addr);
197
198Elf_Sym* dladdr_find_symbol(soinfo* si, const void* addr);
199Elf_Sym* dlsym_handle_lookup(soinfo* si, const char* name);
200
201void debuggerd_init();
202extern "C" abort_msg_t* gAbortMessage;
203extern "C" void notify_gdb_of_libraries();
204
205char* linker_get_error_buffer();
206size_t linker_get_error_buffer_size();
207
208#endif
209