1/*
2 * Copyright (c) 2003-2005 The Regents of The University of Michigan
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 are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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30 */
31
32#include <string>
33
34// Because of the -Wundef flag we have to do this
35#define __LIBELF_INTERNAL__ 0
36#define __LIBELF_NEED_LINK_H 0
37#define __LIBELF_SYMBOL_VERSIONS 0
38
39#include "gelf.h"
40
41#include "base/loader/elf_object.hh"
42#include "base/misc.hh"
43
44#include "base/loader/symtab.hh"
45
46#include "base/trace.hh" // for DPRINTF
47
48#include "sim/byteswap.hh"
49
50
51using namespace std;
52
53ObjectFile *
54ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data)
55{
56 Elf *elf;
57 GElf_Ehdr ehdr;
58 Arch arch = UnknownArch;
59 OpSys opSys = UnknownOpSys;
60
61 // check that header matches library version
62 if (elf_version(EV_CURRENT) == EV_NONE)
63 panic("wrong elf version number!");
64
65 // get a pointer to elf structure
66 elf = elf_memory((char*)data,len);
67 // will only fail if fd is invalid
68 assert(elf != NULL);
69
70 // Check that we actually have a elf file
71 if (gelf_getehdr(elf, &ehdr) ==0) {
72 DPRINTFR(Loader, "Not ELF\n");
73 elf_end(elf);
74 return NULL;
75 } else {
76 //Detect the architecture
77 //Since we don't know how to check for alpha right now, we'll
78 //just assume if it wasn't something else and it's 64 bit, that's
79 //what it must be.
80 if (ehdr.e_machine == EM_SPARC64 ||
81 ehdr.e_machine == EM_SPARC ||
82 ehdr.e_machine == EM_SPARCV9) {
83 arch = ObjectFile::SPARC;
84 } else if (ehdr.e_machine == EM_MIPS
85 && ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
86 arch = ObjectFile::Mips;
87 } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
88 arch = ObjectFile::Alpha;
89 } else {
90 warn("Unknown architecture: %d\n", ehdr.e_machine);
91 arch = ObjectFile::UnknownArch;
92 }
93
94 //Detect the operating system
95 switch (ehdr.e_ident[EI_OSABI])
96 {
97
98 case ELFOSABI_LINUX:
99 opSys = ObjectFile::Linux;
100 break;
101 case ELFOSABI_SOLARIS:
102 opSys = ObjectFile::Solaris;
103 break;
104 case ELFOSABI_TRU64:
105 opSys = ObjectFile::Tru64;
106 break;
107 default:
108 opSys = ObjectFile::UnknownOpSys;
109 }
110
111 //take a look at the .note.ABI section
112 //It can let us know what's what.
113 if (opSys == ObjectFile::UnknownOpSys) {
114 Elf_Scn *section;
115 GElf_Shdr shdr;
116 Elf_Data *data;
117 uint32_t osAbi;;
118 int secIdx = 1;
119
120 // Get the first section
121 section = elf_getscn(elf, secIdx);
122
123 // While there are no more sections
124 while (section != NULL && opSys == ObjectFile::UnknownOpSys) {
125 gelf_getshdr(section, &shdr);
126 if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag",
127 elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) {
128 // we have found a ABI note section
129 // Check the 5th 32bit word for OS 0 == linux, 1 == hurd,
130 // 2 == solaris, 3 == freebsd
131 data = elf_rawdata(section, NULL);
132 assert(data->d_buf);
133 if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
134 osAbi = htole(((uint32_t*)data->d_buf)[4]);
135 else
136 osAbi = htobe(((uint32_t*)data->d_buf)[4]);
137
138 switch(osAbi) {
139 case 0:
140 opSys = ObjectFile::Linux;
141 break;
142 case 2:
143 opSys = ObjectFile::Solaris;
144 break;
145 }
146 } // if section found
147 if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)))
148 opSys = ObjectFile::Solaris;
149 if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)))
150 opSys = ObjectFile::Solaris;
151
152 section = elf_getscn(elf, ++secIdx);
153 } // while sections
154 }
155
156 elf_end(elf);
157 return new ElfObject(fname, fd, len, data, arch, opSys);
158 }
159}
160
161
162ElfObject::ElfObject(const string &_filename, int _fd,
163 size_t _len, uint8_t *_data,
164 Arch _arch, OpSys _opSys)
165 : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys)
166
167{
168 Elf *elf;
169 GElf_Ehdr ehdr;
170
171 // check that header matches library version
172 if (elf_version(EV_CURRENT) == EV_NONE)
173 panic("wrong elf version number!");
174
175 // get a pointer to elf structure
176 elf = elf_memory((char*)fileData,len);
177 // will only fail if fd is invalid
178 assert(elf != NULL);
179
180 // Check that we actually have a elf file
181 if (gelf_getehdr(elf, &ehdr) ==0) {
182 panic("Not ELF, shouldn't be here");
183 }
184
185 entry = ehdr.e_entry;
186
187
188 // initialize segment sizes to 0 in case they're not present
189 text.size = data.size = bss.size = 0;
190
191 for (int i = 0; i < ehdr.e_phnum; ++i) {
192 GElf_Phdr phdr;
193 if (gelf_getphdr(elf, i, &phdr) == 0) {
194 panic("gelf_getphdr failed for section %d", i);
195 }
196
197 // for now we don't care about non-loadable segments
198 if (!(phdr.p_type & PT_LOAD))
199 continue;
200
201 // the headers don't explicitly distinguish text from data,
202 // but empirically the text segment comes first.
203 if (text.size == 0) { // haven't seen text segment yet
204 text.baseAddr = phdr.p_vaddr;
205 text.size = phdr.p_filesz;
206 text.fileImage = fileData + phdr.p_offset;
207 // if there's any padding at the end that's not in the
208 // file, call it the bss. This happens in the "text"
209 // segment if there's only one loadable segment (as for
210 // kernel images).
211 bss.size = phdr.p_memsz - phdr.p_filesz;
212 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
213 bss.fileImage = NULL;
214 } else if (data.size == 0) { // have text, this must be data
215 data.baseAddr = phdr.p_vaddr;
216 data.size = phdr.p_filesz;
217 data.fileImage = fileData + phdr.p_offset;
218 // if there's any padding at the end that's not in the
219 // file, call it the bss. Warn if this happens for both
220 // the text & data segments (should only have one bss).
221 if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) {
222 warn("Two implied bss segments in file!\n");
223 }
224 bss.size = phdr.p_memsz - phdr.p_filesz;
225 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
226 bss.fileImage = NULL;
227 } else {
228 warn("More than two loadable segments in ELF object.");
229 warn("Ignoring segment @ 0x%x length 0x%x.",
230 phdr.p_vaddr, phdr.p_filesz);
231 }
232 }
233
234 // should have found at least one loadable segment
235 assert(text.size != 0);
236
237 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n",
238 text.baseAddr, text.size, data.baseAddr, data.size,
239 bss.baseAddr, bss.size);
240
241 elf_end(elf);
242
243 // We will actually read the sections when we need to load them
244}
245
246
247bool
248ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding)
249{
250 Elf *elf;
251 int sec_idx = 1; // there is a 0 but it is nothing, go figure
252 Elf_Scn *section;
253 GElf_Shdr shdr;
254 Elf_Data *data;
255 int count, ii;
256 bool found = false;
257 GElf_Sym sym;
258
259 if (!symtab)
260 return false;
261
262 // check that header matches library version
263 if (elf_version(EV_CURRENT) == EV_NONE)
264 panic("wrong elf version number!");
265
266 // get a pointer to elf structure
267 elf = elf_memory((char*)fileData,len);
268
269 assert(elf != NULL);
270
271 // Get the first section
272 section = elf_getscn(elf, sec_idx);
273
274 // While there are no more sections
275 while (section != NULL) {
276 gelf_getshdr(section, &shdr);
277
278 if (shdr.sh_type == SHT_SYMTAB) {
279 found = true;
280 data = elf_getdata(section, NULL);
281 count = shdr.sh_size / shdr.sh_entsize;
282 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count);
283
284 // loop through all the symbols, only loading global ones
285 for (ii = 0; ii < count; ++ii) {
286 gelf_getsym(data, ii, &sym);
287 if (GELF_ST_BIND(sym.st_info) == binding) {
288 symtab->insert(sym.st_value,
289 elf_strptr(elf, shdr.sh_link, sym.st_name));
290 }
291 }
292 }
293 ++sec_idx;
294 section = elf_getscn(elf, sec_idx);
295 }
296
297 elf_end(elf);
298
299 return found;
300}
301
302bool
303ElfObject::loadGlobalSymbols(SymbolTable *symtab)
304{
305 return loadSomeSymbols(symtab, STB_GLOBAL);
306}
307
308bool
309ElfObject::loadLocalSymbols(SymbolTable *symtab)
310{
311 return loadSomeSymbols(symtab, STB_LOCAL);
312}
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