linker.h revision bedfe38b8ba512dd6236c00e8b4a9b01c2bd1281 
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
41#undef PAGE_MASK
42#undef PAGE_SIZE
43#define PAGE_SIZE 4096
44#define PAGE_MASK (PAGE_SIZE-1)
45
46/* Convenience macros to make page address/offset computations more explicit */
47
48/* Returns the address of the page starting at address 'x' */
49#define PAGE_START(x)  ((x) & ~PAGE_MASK)
50
51/* Returns the offset of address 'x' in its memory page, i.e. this is the
52 * same than 'x' - PAGE_START(x) */
53#define PAGE_OFFSET(x) ((x) & PAGE_MASK)
54
55/* Returns the address of the next page after address 'x', unless 'x' is
56 * itself at the start of a page. Equivalent to:
57 *
58 *  (x == PAGE_START(x)) ? x : PAGE_START(x)+PAGE_SIZE
59 */
60#define PAGE_END(x)    PAGE_START((x) + (PAGE_SIZE-1))
61
62void debugger_init();
63
64/* magic shared structures that GDB knows about */
65
66struct link_map
67{
68    uintptr_t l_addr;
69    char * l_name;
70    uintptr_t l_ld;
71    struct link_map * l_next;
72    struct link_map * l_prev;
73};
74
75/* needed for dl_iterate_phdr to be passed to the callbacks provided */
76struct dl_phdr_info
77{
78    Elf32_Addr dlpi_addr;
79    const char *dlpi_name;
80    const Elf32_Phdr *dlpi_phdr;
81    Elf32_Half dlpi_phnum;
82};
83
84
85// Values for r_debug->state
86enum {
87    RT_CONSISTENT,
88    RT_ADD,
89    RT_DELETE
90};
91
92struct r_debug
93{
94    int32_t r_version;
95    struct link_map * r_map;
96    void (*r_brk)(void);
97    int32_t r_state;
98    uintptr_t r_ldbase;
99};
100
101typedef struct soinfo soinfo;
102
103#define FLAG_LINKED     0x00000001
104#define FLAG_ERROR      0x00000002
105#define FLAG_EXE        0x00000004 // The main executable
106#define FLAG_LINKER     0x00000010 // The linker itself
107
108#define SOINFO_NAME_LEN 128
109
110struct soinfo
111{
112    char name[SOINFO_NAME_LEN];
113    const Elf32_Phdr *phdr;
114    int phnum;
115    unsigned entry;
116    unsigned base;
117    unsigned size;
118
119    int unused;  // DO NOT USE, maintained for compatibility.
120
121    unsigned *dynamic;
122
123    unsigned unused2; // DO NOT USE, maintained for compatibility
124    unsigned unused3; // DO NOT USE, maintained for compatibility
125
126    soinfo *next;
127    unsigned flags;
128
129    const char *strtab;
130    Elf32_Sym *symtab;
131
132    unsigned nbucket;
133    unsigned nchain;
134    unsigned *bucket;
135    unsigned *chain;
136
137    unsigned *plt_got;
138
139    Elf32_Rel *plt_rel;
140    unsigned plt_rel_count;
141
142    Elf32_Rel *rel;
143    unsigned rel_count;
144
145    unsigned *preinit_array;
146    unsigned preinit_array_count;
147
148    unsigned *init_array;
149    unsigned init_array_count;
150    unsigned *fini_array;
151    unsigned fini_array_count;
152
153    void (*init_func)(void);
154    void (*fini_func)(void);
155
156#if defined(ANDROID_ARM_LINKER)
157    /* ARM EABI section used for stack unwinding. */
158    unsigned *ARM_exidx;
159    unsigned ARM_exidx_count;
160#elif defined(ANDROID_MIPS_LINKER)
161#if 0
162     /* not yet */
163     unsigned *mips_pltgot
164#endif
165     unsigned mips_symtabno;
166     unsigned mips_local_gotno;
167     unsigned mips_gotsym;
168#endif /* ANDROID_*_LINKER */
169
170    unsigned refcount;
171    struct link_map linkmap;
172
173    int constructors_called;
174
175    /* When you read a virtual address from the ELF file, add this
176     * value to get the corresponding address in the process' address space */
177    Elf32_Addr load_bias;
178    int has_text_relocations;
179};
180
181
182extern soinfo libdl_info;
183
184
185#include <asm/elf.h>
186
187#if defined(ANDROID_ARM_LINKER)
188
189// These aren't defined in <arch-arm/asm/elf.h>.
190#define R_ARM_REL32      3
191#define R_ARM_COPY       20
192#define R_ARM_GLOB_DAT   21
193#define R_ARM_JUMP_SLOT  22
194#define R_ARM_RELATIVE   23
195
196#elif defined(ANDROID_MIPS_LINKER)
197
198// These aren't defined in <arch-arm/mips/elf.h>.
199#define R_MIPS_JUMP_SLOT       127
200
201#define DT_MIPS_PLTGOT         0x70000032
202#define DT_MIPS_RWPLT          0x70000034
203
204#elif defined(ANDROID_X86_LINKER)
205
206// x86 has everything it needs in <arch-arm/x86/elf.h>.
207
208#endif /* ANDROID_*_LINKER */
209
210#ifndef DT_INIT_ARRAY
211#define DT_INIT_ARRAY      25
212#endif
213
214#ifndef DT_FINI_ARRAY
215#define DT_FINI_ARRAY      26
216#endif
217
218#ifndef DT_INIT_ARRAYSZ
219#define DT_INIT_ARRAYSZ    27
220#endif
221
222#ifndef DT_FINI_ARRAYSZ
223#define DT_FINI_ARRAYSZ    28
224#endif
225
226#ifndef DT_PREINIT_ARRAY
227#define DT_PREINIT_ARRAY   32
228#endif
229
230#ifndef DT_PREINIT_ARRAYSZ
231#define DT_PREINIT_ARRAYSZ 33
232#endif
233
234soinfo *find_library(const char *name);
235Elf32_Sym *lookup(const char *name, soinfo **found, soinfo *start);
236soinfo *find_containing_library(const void *addr);
237const char *linker_get_error(void);
238
239int soinfo_unload(soinfo* si);
240Elf32_Sym *soinfo_find_symbol(soinfo* si, const void *addr);
241Elf32_Sym *soinfo_lookup(soinfo *si, const char *name);
242void soinfo_call_constructors(soinfo *si);
243
244#if defined(ANDROID_ARM_LINKER)
245typedef long unsigned int *_Unwind_Ptr;
246_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int *pcount);
247#elif defined(ANDROID_X86_LINKER) || defined(ANDROID_MIPS_LINKER)
248int dl_iterate_phdr(int (*cb)(struct dl_phdr_info *, size_t, void *), void *);
249#endif
250
251#ifdef __cplusplus
252};
253#endif
254
255#endif
256