linker_phdr.h revision 650be4e584eeab3591b9e273bfd6d169eea60853 
1/*
2 * Copyright (C) 2012 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#ifndef LINKER_PHDR_H
29#define LINKER_PHDR_H
30
31/* Declarations related to the ELF program header table and segments.
32 *
33 * The design goal is to provide an API that is as close as possible
34 * to the ELF spec, and does not depend on linker-specific data
35 * structures (e.g. the exact layout of struct soinfo).
36 */
37
38#include "linker.h"
39
40class ElfReader {
41 public:
42  ElfReader(const char* name, int fd);
43  ~ElfReader();
44
45  bool Load();
46
47  size_t phdr_count() { return phdr_num_; }
48  Elf32_Addr load_start() { return reinterpret_cast<Elf32_Addr>(load_start_); }
49  Elf32_Addr load_size() { return load_size_; }
50  Elf32_Addr load_bias() { return load_bias_; }
51  const Elf32_Phdr* loaded_phdr() { return loaded_phdr_; }
52
53 private:
54  bool ReadElfHeader();
55  bool VerifyElfHeader();
56  bool ReadProgramHeader();
57  bool ReserveAddressSpace();
58  bool LoadSegments();
59  bool FindPhdr();
60  bool CheckPhdr(Elf32_Addr);
61
62  const char* name_;
63  int fd_;
64
65  Elf32_Ehdr header_;
66  size_t phdr_num_;
67
68  void* phdr_mmap_;
69  Elf32_Phdr* phdr_table_;
70  Elf32_Addr phdr_size_;
71
72  // First page of reserved address space.
73  void* load_start_;
74  // Size in bytes of reserved address space.
75  Elf32_Addr load_size_;
76  // Load bias.
77  Elf32_Addr load_bias_;
78
79  // Loaded phdr.
80  const Elf32_Phdr* loaded_phdr_;
81};
82
83Elf32_Addr phdr_table_get_load_size(const Elf32_Phdr* phdr, size_t phnum);
84
85int
86phdr_table_protect_segments(const Elf32_Phdr* phdr_table,
87                            int               phdr_count,
88                            Elf32_Addr        load_bias);
89
90int
91phdr_table_unprotect_segments(const Elf32_Phdr* phdr_table,
92                              int               phdr_count,
93                              Elf32_Addr        load_bias);
94
95int
96phdr_table_protect_gnu_relro(const Elf32_Phdr* phdr_table,
97                             int               phdr_count,
98                             Elf32_Addr        load_bias);
99
100
101#ifdef ANDROID_ARM_LINKER
102int
103phdr_table_get_arm_exidx(const Elf32_Phdr* phdr_table,
104                         int               phdr_count,
105                         Elf32_Addr        load_bias,
106                         Elf32_Addr**      arm_exidx,
107                         unsigned*         arm_exidix_count);
108#endif
109
110void
111phdr_table_get_dynamic_section(const Elf32_Phdr* phdr_table,
112                               int               phdr_count,
113                               Elf32_Addr        load_bias,
114                               Elf32_Dyn**       dynamic,
115                               size_t*           dynamic_count,
116                               Elf32_Word*       dynamic_flags);
117
118#endif /* LINKER_PHDR_H */
119