linker.h revision 16084168111cd7d2ac8a6b92e6fa6df5696928a5 
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#undef PAGE_MASK
38#undef PAGE_SIZE
39#define PAGE_SIZE 4096
40#define PAGE_MASK 4095
41
42void debugger_init();
43const char *addr_to_name(unsigned addr);
44
45/* magic shared structures that GDB knows about */
46
47struct link_map
48{
49    uintptr_t l_addr;
50    char * l_name;
51    uintptr_t l_ld;
52    struct link_map * l_next;
53    struct link_map * l_prev;
54};
55
56/* needed for dl_iterate_phdr to be passed to the callbacks provided */
57struct dl_phdr_info
58{
59    Elf32_Addr dlpi_addr;
60    const char *dlpi_name;
61    const Elf32_Phdr *dlpi_phdr;
62    Elf32_Half dlpi_phnum;
63};
64
65
66// Values for r_debug->state
67enum {
68    RT_CONSISTENT,
69    RT_ADD,
70    RT_DELETE
71};
72
73struct r_debug
74{
75    int32_t r_version;
76    struct link_map * r_map;
77    void (*r_brk)(void);
78    int32_t r_state;
79    uintptr_t r_ldbase;
80};
81
82typedef struct soinfo soinfo;
83
84#define FLAG_LINKED     0x00000001
85#define FLAG_ERROR      0x00000002
86#define FLAG_EXE        0x00000004 // The main executable
87#define FLAG_LINKER     0x00000010 // The linker itself
88
89#define SOINFO_NAME_LEN 128
90
91struct soinfo
92{
93    const char name[SOINFO_NAME_LEN];
94    Elf32_Phdr *phdr;
95    int phnum;
96    unsigned entry;
97    unsigned base;
98    unsigned size;
99
100    int unused;  // DO NOT USE, maintained for compatibility.
101
102    unsigned *dynamic;
103
104    unsigned wrprotect_start;
105    unsigned wrprotect_end;
106
107    soinfo *next;
108    unsigned flags;
109
110    const char *strtab;
111    Elf32_Sym *symtab;
112
113    unsigned nbucket;
114    unsigned nchain;
115    unsigned *bucket;
116    unsigned *chain;
117
118    unsigned *plt_got;
119
120    Elf32_Rel *plt_rel;
121    unsigned plt_rel_count;
122
123    Elf32_Rel *rel;
124    unsigned rel_count;
125
126    unsigned *preinit_array;
127    unsigned preinit_array_count;
128
129    unsigned *init_array;
130    unsigned init_array_count;
131    unsigned *fini_array;
132    unsigned fini_array_count;
133
134    void (*init_func)(void);
135    void (*fini_func)(void);
136
137#ifdef ANDROID_ARM_LINKER
138    /* ARM EABI section used for stack unwinding. */
139    unsigned *ARM_exidx;
140    unsigned ARM_exidx_count;
141#endif
142
143    unsigned refcount;
144    struct link_map linkmap;
145
146    int constructors_called;
147
148    Elf32_Addr gnu_relro_start;
149    unsigned gnu_relro_len;
150
151    /* When you read a virtual address from the ELF file, add the load
152     * address (= "base" field) minus this value (= "load_offset") to get the
153     * real, corresponding address in the process' address space */
154    Elf32_Addr load_offset;
155};
156
157
158extern soinfo libdl_info;
159
160#ifdef ANDROID_ARM_LINKER
161
162#define R_ARM_COPY       20
163#define R_ARM_GLOB_DAT   21
164#define R_ARM_JUMP_SLOT  22
165#define R_ARM_RELATIVE   23
166
167/* According to the AAPCS specification, we only
168 * need the above relocations. However, in practice,
169 * the following ones turn up from time to time.
170 */
171#define R_ARM_ABS32      2
172#define R_ARM_REL32      3
173
174#elif defined(ANDROID_X86_LINKER)
175
176#define R_386_32         1
177#define R_386_PC32       2
178#define R_386_GLOB_DAT   6
179#define R_386_JUMP_SLOT  7
180#define R_386_RELATIVE   8
181
182#endif
183
184#ifndef DT_INIT_ARRAY
185#define DT_INIT_ARRAY      25
186#endif
187
188#ifndef DT_FINI_ARRAY
189#define DT_FINI_ARRAY      26
190#endif
191
192#ifndef DT_INIT_ARRAYSZ
193#define DT_INIT_ARRAYSZ    27
194#endif
195
196#ifndef DT_FINI_ARRAYSZ
197#define DT_FINI_ARRAYSZ    28
198#endif
199
200#ifndef DT_PREINIT_ARRAY
201#define DT_PREINIT_ARRAY   32
202#endif
203
204#ifndef DT_PREINIT_ARRAYSZ
205#define DT_PREINIT_ARRAYSZ 33
206#endif
207
208soinfo *find_library(const char *name);
209Elf32_Sym *lookup(const char *name, soinfo **found, soinfo *start);
210soinfo *find_containing_library(const void *addr);
211const char *linker_get_error(void);
212
213unsigned soinfo_unload(soinfo *si);
214Elf32_Sym *soinfo_find_symbol(soinfo* si, const void *addr);
215Elf32_Sym *soinfo_lookup(soinfo *si, const char *name);
216void soinfo_call_constructors(soinfo *si);
217
218#ifdef ANDROID_ARM_LINKER
219typedef long unsigned int *_Unwind_Ptr;
220_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int *pcount);
221#elif defined(ANDROID_X86_LINKER)
222int dl_iterate_phdr(int (*cb)(struct dl_phdr_info *, size_t, void *), void *);
223#endif
224
225#endif
226