linker.h revision b7beb6907599b36809effe1b4db76039ac649518 
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#ifdef __cplusplus
38extern "C" {
39#endif
40#include <link.h>
41
42#undef PAGE_MASK
43#undef PAGE_SIZE
44#define PAGE_SIZE 4096
45#define PAGE_MASK (PAGE_SIZE-1)
46
47/* Convenience macros to make page address/offset computations more explicit */
48
49/* Returns the address of the page starting at address 'x' */
50#define PAGE_START(x)  ((x) & ~PAGE_MASK)
51
52/* Returns the offset of address 'x' in its memory page, i.e. this is the
53 * same than 'x' - PAGE_START(x) */
54#define PAGE_OFFSET(x) ((x) & PAGE_MASK)
55
56/* Returns the address of the next page after address 'x', unless 'x' is
57 * itself at the start of a page. Equivalent to:
58 *
59 *  (x == PAGE_START(x)) ? x : PAGE_START(x)+PAGE_SIZE
60 */
61#define PAGE_END(x)    PAGE_START((x) + (PAGE_SIZE-1))
62
63void debugger_init();
64
65/* magic shared structures that GDB knows about */
66
67struct link_map
68{
69    uintptr_t l_addr;
70    char * l_name;
71    uintptr_t l_ld;
72    struct link_map * l_next;
73    struct link_map * l_prev;
74};
75
76// Values for r_debug->state
77enum {
78    RT_CONSISTENT,
79    RT_ADD,
80    RT_DELETE
81};
82
83struct r_debug
84{
85    int32_t r_version;
86    struct link_map * r_map;
87    void (*r_brk)(void);
88    int32_t r_state;
89    uintptr_t r_ldbase;
90};
91
92typedef struct soinfo soinfo;
93
94#define FLAG_LINKED     0x00000001
95#define FLAG_ERROR      0x00000002
96#define FLAG_EXE        0x00000004 // The main executable
97#define FLAG_LINKER     0x00000010 // The linker itself
98
99#define SOINFO_NAME_LEN 128
100
101struct soinfo
102{
103    char name[SOINFO_NAME_LEN];
104    const Elf32_Phdr *phdr;
105    int phnum;
106    unsigned entry;
107    unsigned base;
108    unsigned size;
109
110    int unused;  // DO NOT USE, maintained for compatibility.
111
112    unsigned *dynamic;
113
114    unsigned unused2; // DO NOT USE, maintained for compatibility
115    unsigned unused3; // DO NOT USE, maintained for compatibility
116
117    soinfo *next;
118    unsigned flags;
119
120    const char *strtab;
121    Elf32_Sym *symtab;
122
123    unsigned nbucket;
124    unsigned nchain;
125    unsigned *bucket;
126    unsigned *chain;
127
128    unsigned *plt_got;
129
130    Elf32_Rel *plt_rel;
131    unsigned plt_rel_count;
132
133    Elf32_Rel *rel;
134    unsigned rel_count;
135
136    unsigned *preinit_array;
137    unsigned preinit_array_count;
138
139    unsigned *init_array;
140    unsigned init_array_count;
141    unsigned *fini_array;
142    unsigned fini_array_count;
143
144    void (*init_func)(void);
145    void (*fini_func)(void);
146
147#if defined(ANDROID_ARM_LINKER)
148    /* ARM EABI section used for stack unwinding. */
149    unsigned *ARM_exidx;
150    unsigned ARM_exidx_count;
151#elif defined(ANDROID_MIPS_LINKER)
152#if 0
153     /* not yet */
154     unsigned *mips_pltgot
155#endif
156     unsigned mips_symtabno;
157     unsigned mips_local_gotno;
158     unsigned mips_gotsym;
159#endif /* ANDROID_*_LINKER */
160
161    unsigned refcount;
162    struct link_map linkmap;
163
164    int constructors_called;
165
166    /* When you read a virtual address from the ELF file, add this
167     * value to get the corresponding address in the process' address space */
168    Elf32_Addr load_bias;
169    int has_text_relocations;
170};
171
172
173extern soinfo libdl_info;
174
175
176#include <asm/elf.h>
177
178#if defined(ANDROID_ARM_LINKER)
179
180// These aren't defined in <arch-arm/asm/elf.h>.
181#define R_ARM_REL32      3
182#define R_ARM_COPY       20
183#define R_ARM_GLOB_DAT   21
184#define R_ARM_JUMP_SLOT  22
185#define R_ARM_RELATIVE   23
186
187#elif defined(ANDROID_MIPS_LINKER)
188
189// These aren't defined in <arch-arm/mips/elf.h>.
190#define R_MIPS_JUMP_SLOT       127
191
192#define DT_MIPS_PLTGOT         0x70000032
193#define DT_MIPS_RWPLT          0x70000034
194
195#elif defined(ANDROID_X86_LINKER)
196
197// x86 has everything it needs in <arch-arm/x86/elf.h>.
198
199#endif /* ANDROID_*_LINKER */
200
201#ifndef DT_INIT_ARRAY
202#define DT_INIT_ARRAY      25
203#endif
204
205#ifndef DT_FINI_ARRAY
206#define DT_FINI_ARRAY      26
207#endif
208
209#ifndef DT_INIT_ARRAYSZ
210#define DT_INIT_ARRAYSZ    27
211#endif
212
213#ifndef DT_FINI_ARRAYSZ
214#define DT_FINI_ARRAYSZ    28
215#endif
216
217#ifndef DT_PREINIT_ARRAY
218#define DT_PREINIT_ARRAY   32
219#endif
220
221#ifndef DT_PREINIT_ARRAYSZ
222#define DT_PREINIT_ARRAYSZ 33
223#endif
224
225soinfo *find_library(const char *name);
226Elf32_Sym *lookup(const char *name, soinfo **found, soinfo *start);
227soinfo *find_containing_library(const void *addr);
228const char *linker_get_error(void);
229
230int soinfo_unload(soinfo* si);
231Elf32_Sym *soinfo_find_symbol(soinfo* si, const void *addr);
232Elf32_Sym *soinfo_lookup(soinfo *si, const char *name);
233void soinfo_call_constructors(soinfo *si);
234
235#ifdef __cplusplus
236};
237#endif
238
239#endif
240