linker.h revision 4688279db5dcc4004941e7f133c4a1c3617d842c 
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();
63const char *addr_to_name(unsigned addr);
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/* needed for dl_iterate_phdr to be passed to the callbacks provided */
77struct dl_phdr_info
78{
79    Elf32_Addr dlpi_addr;
80    const char *dlpi_name;
81    const Elf32_Phdr *dlpi_phdr;
82    Elf32_Half dlpi_phnum;
83};
84
85
86// Values for r_debug->state
87enum {
88    RT_CONSISTENT,
89    RT_ADD,
90    RT_DELETE
91};
92
93struct r_debug
94{
95    int32_t r_version;
96    struct link_map * r_map;
97    void (*r_brk)(void);
98    int32_t r_state;
99    uintptr_t r_ldbase;
100};
101
102typedef struct soinfo soinfo;
103
104#define FLAG_LINKED     0x00000001
105#define FLAG_ERROR      0x00000002
106#define FLAG_EXE        0x00000004 // The main executable
107#define FLAG_LINKER     0x00000010 // The linker itself
108
109#define SOINFO_NAME_LEN 128
110
111struct soinfo
112{
113    char name[SOINFO_NAME_LEN];
114    const Elf32_Phdr *phdr;
115    int phnum;
116    unsigned entry;
117    unsigned base;
118    unsigned size;
119
120    int unused;  // DO NOT USE, maintained for compatibility.
121
122    unsigned *dynamic;
123
124    unsigned unused2; // DO NOT USE, maintained for compatibility
125    unsigned unused3; // DO NOT USE, maintained for compatibility
126
127    soinfo *next;
128    unsigned flags;
129
130    const char *strtab;
131    Elf32_Sym *symtab;
132
133    unsigned nbucket;
134    unsigned nchain;
135    unsigned *bucket;
136    unsigned *chain;
137
138    unsigned *plt_got;
139
140    Elf32_Rel *plt_rel;
141    unsigned plt_rel_count;
142
143    Elf32_Rel *rel;
144    unsigned rel_count;
145
146    unsigned *preinit_array;
147    unsigned preinit_array_count;
148
149    unsigned *init_array;
150    unsigned init_array_count;
151    unsigned *fini_array;
152    unsigned fini_array_count;
153
154    void (*init_func)(void);
155    void (*fini_func)(void);
156
157#if defined(ANDROID_ARM_LINKER)
158    /* ARM EABI section used for stack unwinding. */
159    unsigned *ARM_exidx;
160    unsigned ARM_exidx_count;
161#elif defined(ANDROID_MIPS_LINKER)
162#if 0
163     /* not yet */
164     unsigned *mips_pltgot
165#endif
166     unsigned mips_symtabno;
167     unsigned mips_local_gotno;
168     unsigned mips_gotsym;
169#endif /* ANDROID_*_LINKER */
170
171    unsigned refcount;
172    struct link_map linkmap;
173
174    int constructors_called;
175
176    /* When you read a virtual address from the ELF file, add this
177     * value to get the corresponding address in the process' address space */
178    Elf32_Addr load_bias;
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
239unsigned 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