1 /*
2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_UTILITIES_ELF_FILE_HPP
26 #define SHARE_VM_UTILITIES_ELF_FILE_HPP
27
28 #if !defined(_WINDOWS) && !defined(__APPLE__)
29
30 #if defined(__OpenBSD__)
31 #include <sys/exec_elf.h>
32 #else
33 #include <elf.h>
34 #endif
35 #include <stdio.h>
36
37 #ifdef _LP64
38
39 typedef Elf64_Half Elf_Half;
40 typedef Elf64_Word Elf_Word;
41 typedef Elf64_Off Elf_Off;
42 typedef Elf64_Addr Elf_Addr;
43
44 typedef Elf64_Ehdr Elf_Ehdr;
45 typedef Elf64_Shdr Elf_Shdr;
46 typedef Elf64_Phdr Elf_Phdr;
47 typedef Elf64_Sym Elf_Sym;
48 typedef Elf64_Nhdr Elf_Nhdr;
49
50 #if !defined(_ALLBSD_SOURCE) || defined(__APPLE__)
51 #define ELF_ST_TYPE ELF64_ST_TYPE
52 #endif
53
54 #else
55
56 typedef Elf32_Half Elf_Half;
57 typedef Elf32_Word Elf_Word;
58 typedef Elf32_Off Elf_Off;
59 typedef Elf32_Addr Elf_Addr;
60
61 typedef Elf32_Ehdr Elf_Ehdr;
62 typedef Elf32_Shdr Elf_Shdr;
63 typedef Elf32_Phdr Elf_Phdr;
64 typedef Elf32_Sym Elf_Sym;
65 typedef Elf32_Nhdr Elf_Nhdr;
66
67 #if !defined(_ALLBSD_SOURCE) || defined(__APPLE__)
68 #define ELF_ST_TYPE ELF32_ST_TYPE
69 #endif
70 #endif
71
72 #include "globalDefinitions.hpp"
73 #include "memory/allocation.hpp"
74 #include "utilities/decoder.hpp"
75
76 class ElfStringTable;
77 class ElfSymbolTable;
78 class ElfFuncDescTable;
79
80 // ELF section, may or may not have cached data
81 class ElfSection VALUE_OBJ_CLASS_SPEC {
82 private:
83 Elf_Shdr _section_hdr;
84 void* _section_data;
85 NullDecoder::decoder_status _stat;
86 public:
87 ElfSection(FILE* fd, const Elf_Shdr& hdr);
88 ~ElfSection();
89
90 NullDecoder::decoder_status status() const { return _stat; }
91
92 const Elf_Shdr* section_header() const { return &_section_hdr; }
93 const void* section_data() const { return (const void*)_section_data; }
94 private:
95 // load this section.
96 // it return no_error, when it fails to cache the section data due to lack of memory
97 NullDecoder::decoder_status load_section(FILE* const file, const Elf_Shdr& hdr);
98 };
99
100 class FileReader : public StackObj {
101 protected:
102 FILE* const _fd;
103 public:
104 FileReader(FILE* const fd) : _fd(fd) {};
105 bool read(void* buf, size_t size);
106 int read_buffer(void* buf, size_t size);
107 bool set_position(long offset);
108 };
109
110 // Mark current position, so we can get back to it after
111 // reads.
112 class MarkedFileReader : public FileReader {
113 private:
114 long _marked_pos;
115 public:
116 MarkedFileReader(FILE* const fd);
117 ~MarkedFileReader();
118
119 bool has_mark() const { return _marked_pos >= 0; }
120 };
121
122 // Interface to external debug info file
123 class ElfDebugInfo : public CHeapObj<mtInternal> {
124 public:
125 virtual bool decode(address addr, char* const buf, size_t buflen, int* offset) = 0;
126 virtual bool has_error() const = 0;
127 };
128
129 // ElfFile is basically an elf file parser, which can lookup the symbol
130 // that is the nearest to the given address.
131 // Beware, this code is called from vm error reporting code, when vm is already
132 // in "error" state, so there are scenarios, lookup will fail. We want this
133 // part of code to be very defensive, and bait out if anything went wrong.
134 class ElfFile: public CHeapObj<mtInternal> {
135 friend class ElfDecoder;
136
137 private:
138 // link ElfFiles
139 ElfFile* _next;
140
141 // Elf file
142 char* _filepath;
143 FILE* _file;
144
145 // Elf header
146 Elf_Ehdr _elfHdr;
147
148 // symbol tables
149 ElfSymbolTable* _symbol_tables;
150
151 // regular string tables
152 ElfStringTable* _string_tables;
153
154 // section header string table, used for finding section name
155 ElfStringTable* _shdr_string_table;
156
157 // function descriptors table
158 ElfFuncDescTable* _funcDesc_table;
159
160 // external debug info
161 ElfDebugInfo* _debuginfo;
162
163 NullDecoder::decoder_status _status;
164
165 public:
166 ElfFile(const char* filepath, bool load_debug_info = true);
167 ~ElfFile();
168
169 bool decode(address addr, char* buf, int buflen, int* offset);
170
171 const char* filepath() const {
172 return _filepath;
173 }
174
175 bool same_elf_file(const char* filepath) const {
176 assert(filepath != NULL, "null file path");
177 return (_filepath != NULL && !strcmp(filepath, _filepath));
178 }
179
180 NullDecoder::decoder_status get_status() const {
181 return _status;
182 }
183
184 // Returns true if the elf file is marked NOT to require an executable stack,
185 // or if the file could not be opened.
186 // Returns false if the elf file requires an executable stack, the stack flag
187 // is not set at all, or if the file can not be read.
188 // On systems other than linux it always returns false.
189 static bool specifies_noexecstack(const char* filepath) NOT_LINUX({ return false; });
190 private:
191 // sanity check, if the file is a real elf file
192 static bool is_elf_file(Elf_Ehdr&);
193
194 // parse this elf file
195 NullDecoder::decoder_status parse_elf(const char* filename);
196
197 // load external debuginfo file for this file.
198 ElfDebugInfo* load_debuginfo() NOT_LINUX({ return NULL; });
199
200 // internal implementation
201 bool decode_impl(address addr, char* buf, int buflen, int* offset);
202
203 // load string, symbol and function descriptor tables from the elf file
204 NullDecoder::decoder_status load_tables();
205
206 ElfFile* next() const { return _next; }
207 void set_next(ElfFile* file) { _next = file; }
208
209 // find a section by name, return section index
210 // if there is no such section, return -1
211 int section_by_name(const char* name, Elf_Shdr& hdr);
212
213 // string tables are stored in a linked list
214 void add_string_table(ElfStringTable* table);
215
216 // symbol tables are stored in a linked list
217 void add_symbol_table(ElfSymbolTable* table);
218
219 // return a string table at specified section index
220 ElfStringTable* get_string_table(int index);
221
222
223 FILE* const fd() const { return _file; }
224
225 // Cleanup string, symbol and function descriptor tables
226 void cleanup_tables();
227
228 public:
229 // For whitebox test
230 static bool _do_not_cache_elf_section;
231 };
232
233 #endif // !_WINDOWS && !__APPLE__
234
235 #endif // SHARE_VM_UTILITIES_ELF_FILE_HPP