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.
27 */
28
29#include <string>
30
31// Because of the -Wundef flag we have to do this
32#define __LIBELF_INTERNAL__ 0
33#define __LIBELF_NEED_LINK_H 0
34#define __LIBELF_SYMBOL_VERSIONS 0
35
36#include "gelf.h"
37
38#include "base/loader/elf_object.hh"
39#include "base/misc.hh"
40
41#include "base/loader/symtab.hh"
42
43#include "base/trace.hh" // for DPRINTF
44
45#include "sim/byteswap.hh"
46
47
48using namespace std;
49
50ObjectFile *
51ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data)
52{
53 Elf *elf;
54 GElf_Ehdr ehdr;
55 Arch arch = UnknownArch;
56 OpSys opSys = UnknownOpSys;
57
58 // check that header matches library version
59 if (elf_version(EV_CURRENT) == EV_NONE)
60 panic("wrong elf version number!");
61
62 // get a pointer to elf structure
63 elf = elf_memory((char*)data,len);
64 // will only fail if fd is invalid
65 assert(elf != NULL);
66
67 // Check that we actually have a elf file
68 if (gelf_getehdr(elf, &ehdr) ==0) {
69 DPRINTFR(Loader, "Not ELF\n");
70 elf_end(elf);
71 return NULL;
72 } else {
73 //Detect the architecture
74 //Since we don't know how to check for alpha right now, we'll
75 //just assume if it wasn't something else and it's 64 bit, that's
76 //what it must be.
77 if (ehdr.e_machine == EM_SPARC64 ||
78 ehdr.e_machine == EM_SPARC ||
79 ehdr.e_machine == EM_SPARCV9) {
80 arch = ObjectFile::SPARC;
81 } else if (ehdr.e_machine == EM_MIPS
82 && ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
83 arch = ObjectFile::Mips;
84 } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
85 arch = ObjectFile::Alpha;
86 } else {
87 warn("Unknown architecture: %d\n", ehdr.e_machine);
88 arch = ObjectFile::UnknownArch;
89 }
90
91 //Detect the operating system
92 switch (ehdr.e_ident[EI_OSABI])
93 {
94
95 case ELFOSABI_LINUX:
96 opSys = ObjectFile::Linux;
97 break;
98 case ELFOSABI_SOLARIS:
99 opSys = ObjectFile::Solaris;
100 break;
101 case ELFOSABI_TRU64:
102 opSys = ObjectFile::Tru64;
103 break;
104 default:
105 opSys = ObjectFile::UnknownOpSys;
106 }
107
108 //take a look at the .note.ABI section
109 //It can let us know what's what.
110 if (opSys == ObjectFile::UnknownOpSys) {
111 Elf_Scn *section;
112 GElf_Shdr shdr;
113 Elf_Data *data;
114 uint32_t osAbi;;
115 int secIdx = 1;
116
117 // Get the first section
118 section = elf_getscn(elf, secIdx);
119
120 // While there are no more sections
121 while (section != NULL && opSys == ObjectFile::UnknownOpSys) {
122 gelf_getshdr(section, &shdr);
123 if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag",
124 elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) {
125 // we have found a ABI note section
126 // Check the 5th 32bit word for OS 0 == linux, 1 == hurd,
127 // 2 == solaris, 3 == freebsd
128 data = elf_rawdata(section, NULL);
129 assert(data->d_buf);
130 if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
131 osAbi = htole(((uint32_t*)data->d_buf)[4]);
132 else
133 osAbi = htobe(((uint32_t*)data->d_buf)[4]);
134
135 switch(osAbi) {
136 case 0:
137 opSys = ObjectFile::Linux;
138 break;
139 case 2:
140 opSys = ObjectFile::Solaris;
141 break;
142 }
143 } // if section found
144 if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)))
145 opSys = ObjectFile::Solaris;
146 if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)))
147 opSys = ObjectFile::Solaris;
148
149 section = elf_getscn(elf, ++secIdx);
150 } // while sections
151 }
152
153 elf_end(elf);
154 return new ElfObject(fname, fd, len, data, arch, opSys);
155 }
156}
157
158
159ElfObject::ElfObject(const string &_filename, int _fd,
160 size_t _len, uint8_t *_data,
161 Arch _arch, OpSys _opSys)
162 : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys)
163
164{
165 Elf *elf;
166 GElf_Ehdr ehdr;
167
168 // check that header matches library version
169 if (elf_version(EV_CURRENT) == EV_NONE)
170 panic("wrong elf version number!");
171
172 // get a pointer to elf structure
173 elf = elf_memory((char*)fileData,len);
174 // will only fail if fd is invalid
175 assert(elf != NULL);
176
177 // Check that we actually have a elf file
178 if (gelf_getehdr(elf, &ehdr) ==0) {
179 panic("Not ELF, shouldn't be here");
180 }
181
182 entry = ehdr.e_entry;
183
184
185 // initialize segment sizes to 0 in case they're not present
186 text.size = data.size = bss.size = 0;
187
188 for (int i = 0; i < ehdr.e_phnum; ++i) {
189 GElf_Phdr phdr;
190 if (gelf_getphdr(elf, i, &phdr) == 0) {
191 panic("gelf_getphdr failed for section %d", i);
192 }
193
194 // for now we don't care about non-loadable segments
195 if (!(phdr.p_type & PT_LOAD))
196 continue;
197
198 // the headers don't explicitly distinguish text from data,
199 // but empirically the text segment comes first.
200 if (text.size == 0) { // haven't seen text segment yet
201 text.baseAddr = phdr.p_vaddr;
202 text.size = phdr.p_filesz;
203 text.fileImage = fileData + phdr.p_offset;
204 // if there's any padding at the end that's not in the
205 // file, call it the bss. This happens in the "text"
206 // segment if there's only one loadable segment (as for
207 // kernel images).
208 bss.size = phdr.p_memsz - phdr.p_filesz;
209 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
210 bss.fileImage = NULL;
211 } else if (data.size == 0) { // have text, this must be data
212 data.baseAddr = phdr.p_vaddr;
213 data.size = phdr.p_filesz;
214 data.fileImage = fileData + phdr.p_offset;
215 // if there's any padding at the end that's not in the
216 // file, call it the bss. Warn if this happens for both
217 // the text & data segments (should only have one bss).
218 if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) {
219 warn("Two implied bss segments in file!\n");
220 }
221 bss.size = phdr.p_memsz - phdr.p_filesz;
222 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
223 bss.fileImage = NULL;
224 } else {
225 warn("More than two loadable segments in ELF object.");
226 warn("Ignoring segment @ 0x%x length 0x%x.",
227 phdr.p_vaddr, phdr.p_filesz);
228 }
229 }
230
231 // should have found at least one loadable segment
232 assert(text.size != 0);
233
234 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n",
235 text.baseAddr, text.size, data.baseAddr, data.size,
236 bss.baseAddr, bss.size);
237
238 elf_end(elf);
239
240 // We will actually read the sections when we need to load them
241}
242
243
244bool
245ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding)
246{
247 Elf *elf;
248 int sec_idx = 1; // there is a 0 but it is nothing, go figure
249 Elf_Scn *section;
250 GElf_Shdr shdr;
251 Elf_Data *data;
252 int count, ii;
253 bool found = false;
254 GElf_Sym sym;
255
256 if (!symtab)
257 return false;
258
259 // check that header matches library version
260 if (elf_version(EV_CURRENT) == EV_NONE)
261 panic("wrong elf version number!");
262
263 // get a pointer to elf structure
264 elf = elf_memory((char*)fileData,len);
265
266 assert(elf != NULL);
267
268 // Get the first section
269 section = elf_getscn(elf, sec_idx);
270
271 // While there are no more sections
272 while (section != NULL) {
273 gelf_getshdr(section, &shdr);
274
275 if (shdr.sh_type == SHT_SYMTAB) {
276 found = true;
277 data = elf_getdata(section, NULL);
278 count = shdr.sh_size / shdr.sh_entsize;
279 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count);
280
281 // loop through all the symbols, only loading global ones
282 for (ii = 0; ii < count; ++ii) {
283 gelf_getsym(data, ii, &sym);
284 if (GELF_ST_BIND(sym.st_info) == binding) {
285 symtab->insert(sym.st_value,
286 elf_strptr(elf, shdr.sh_link, sym.st_name));
287 }
288 }
289 }
290 ++sec_idx;
291 section = elf_getscn(elf, sec_idx);
292 }
293
294 elf_end(elf);
295
296 return found;
297}
298
299bool
300ElfObject::loadGlobalSymbols(SymbolTable *symtab)
301{
302 return loadSomeSymbols(symtab, STB_GLOBAL);
303}
304
305bool
306ElfObject::loadLocalSymbols(SymbolTable *symtab)
307{
308 return loadSomeSymbols(symtab, STB_LOCAL);
309}