elf_object.cc revision 5874
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 * Authors: Steve Reinhardt 29 * Ali Saidi 30 */ 31 32#include <cassert> 33#include <string> 34 35#include "gelf.h" 36 37#include "base/loader/elf_object.hh" 38#include "base/loader/symtab.hh" 39#include "base/misc.hh" 40#include "base/trace.hh" // for DPRINTF 41#include "sim/byteswap.hh" 42 43using namespace std; 44 45ObjectFile * 46ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data) 47{ 48 Elf *elf; 49 GElf_Ehdr ehdr; 50 Arch arch = UnknownArch; 51 OpSys opSys = UnknownOpSys; 52 53 // check that header matches library version 54 if (elf_version(EV_CURRENT) == EV_NONE) 55 panic("wrong elf version number!"); 56 57 // get a pointer to elf structure 58 elf = elf_memory((char*)data,len); 59 // will only fail if fd is invalid 60 assert(elf != NULL); 61 62 // Check that we actually have a elf file 63 if (gelf_getehdr(elf, &ehdr) ==0) { 64 DPRINTFR(Loader, "Not ELF\n"); 65 elf_end(elf); 66 return NULL; 67 } else { 68 //Detect the architecture 69 //Since we don't know how to check for alpha right now, we'll 70 //just assume if it wasn't something else and it's 64 bit, that's 71 //what it must be. 72 if (ehdr.e_machine == EM_SPARC64 || 73 (ehdr.e_machine == EM_SPARC && 74 ehdr.e_ident[EI_CLASS] == ELFCLASS64)|| 75 ehdr.e_machine == EM_SPARCV9) { 76 arch = ObjectFile::SPARC64; 77 } else if (ehdr.e_machine == EM_SPARC32PLUS || 78 (ehdr.e_machine == EM_SPARC && 79 ehdr.e_ident[EI_CLASS] == ELFCLASS32)) { 80 arch = ObjectFile::SPARC32; 81 } else if (ehdr.e_machine == EM_MIPS 82 && ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 83 if (ehdr.e_ident[EI_DATA] == ELFDATA2LSB) { 84 arch = ObjectFile::Mips; 85 } else { 86 fatal("The binary you're trying to load is compiled for big " 87 "endian MIPS. M5\nonly supports little endian MIPS. " 88 "Please recompile your binary.\n"); 89 } 90 } else if (ehdr.e_machine == EM_X86_64 && 91 ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 92 arch = ObjectFile::X86_64; 93 } else if (ehdr.e_machine == EM_386 && 94 ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 95 arch = ObjectFile::I386; 96 } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 97 arch = ObjectFile::Alpha; 98 } else if (ehdr.e_machine == EM_ARM) { 99 arch = ObjectFile::Arm; 100 } else { 101 warn("Unknown architecture: %d\n", ehdr.e_machine); 102 arch = ObjectFile::UnknownArch; 103 } 104 105 //Detect the operating system 106 switch (ehdr.e_ident[EI_OSABI]) 107 { 108 109 case ELFOSABI_LINUX: 110 case ELFOSABI_ARM: 111 opSys = ObjectFile::Linux; 112 break; 113 case ELFOSABI_SOLARIS: 114 opSys = ObjectFile::Solaris; 115 break; 116 case ELFOSABI_TRU64: 117 opSys = ObjectFile::Tru64; 118 break; 119 default: 120 opSys = ObjectFile::UnknownOpSys; 121 } 122 123 //take a look at the .note.ABI section 124 //It can let us know what's what. 125 if (opSys == ObjectFile::UnknownOpSys) { 126 Elf_Scn *section; 127 GElf_Shdr shdr; 128 Elf_Data *data; 129 uint32_t osAbi;; 130 int secIdx = 1; 131 132 // Get the first section 133 section = elf_getscn(elf, secIdx); 134 135 // While there are no more sections 136 while (section != NULL && opSys == ObjectFile::UnknownOpSys) { 137 gelf_getshdr(section, &shdr); 138 if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag", 139 elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) { 140 // we have found a ABI note section 141 // Check the 5th 32bit word for OS 0 == linux, 1 == hurd, 142 // 2 == solaris, 3 == freebsd 143 data = elf_rawdata(section, NULL); 144 assert(data->d_buf); 145 if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB) 146 osAbi = htole(((uint32_t*)data->d_buf)[4]); 147 else 148 osAbi = htobe(((uint32_t*)data->d_buf)[4]); 149 150 switch(osAbi) { 151 case 0: 152 opSys = ObjectFile::Linux; 153 break; 154 case 2: 155 opSys = ObjectFile::Solaris; 156 break; 157 } 158 } // if section found 159 if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 160 opSys = ObjectFile::Solaris; 161 if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 162 opSys = ObjectFile::Solaris; 163 164 section = elf_getscn(elf, ++secIdx); 165 } // while sections 166 } 167 168 ElfObject * result = new ElfObject(fname, fd, len, data, arch, opSys); 169 170 //The number of headers in the file 171 result->_programHeaderCount = ehdr.e_phnum; 172 //Record the size of each entry 173 result->_programHeaderSize = ehdr.e_phentsize; 174 if(result->_programHeaderCount) //If there is a program header table 175 { 176 //Figure out the virtual address of the header table in the 177 //final memory image. We use the program headers themselves 178 //to translate from a file offset to the address in the image. 179 GElf_Phdr phdr; 180 uint64_t e_phoff = ehdr.e_phoff; 181 result->_programHeaderTable = 0; 182 for(int hdrnum = 0; hdrnum < result->_programHeaderCount; hdrnum++) 183 { 184 gelf_getphdr(elf, hdrnum, &phdr); 185 //Check if we've found the segment with the headers in it 186 if(phdr.p_offset <= e_phoff && 187 phdr.p_offset + phdr.p_filesz > e_phoff) 188 { 189 result->_programHeaderTable = phdr.p_paddr + e_phoff; 190 break; 191 } 192 } 193 } 194 else 195 result->_programHeaderTable = 0; 196 197 198 elf_end(elf); 199 return result; 200 } 201} 202 203 204ElfObject::ElfObject(const string &_filename, int _fd, 205 size_t _len, uint8_t *_data, 206 Arch _arch, OpSys _opSys) 207 : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys) 208 209{ 210 Elf *elf; 211 GElf_Ehdr ehdr; 212 213 // check that header matches library version 214 if (elf_version(EV_CURRENT) == EV_NONE) 215 panic("wrong elf version number!"); 216 217 // get a pointer to elf structure 218 elf = elf_memory((char*)fileData,len); 219 // will only fail if fd is invalid 220 assert(elf != NULL); 221 222 // Check that we actually have a elf file 223 if (gelf_getehdr(elf, &ehdr) ==0) { 224 panic("Not ELF, shouldn't be here"); 225 } 226 227 entry = ehdr.e_entry; 228 229 // initialize segment sizes to 0 in case they're not present 230 text.size = data.size = bss.size = 0; 231 232 int secIdx = 1; 233 Elf_Scn *section; 234 GElf_Shdr shdr; 235 236 // The first address of some important sections. 237 Addr textSecStart = 0; 238 Addr dataSecStart = 0; 239 Addr bssSecStart = 0; 240 241 // Get the first section 242 section = elf_getscn(elf, secIdx); 243 244 // Find the beginning of the most interesting sections. 245 while (section != NULL) { 246 gelf_getshdr(section, &shdr); 247 char * secName = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name); 248 249 if (!strcmp(".text", secName)) { 250 textSecStart = shdr.sh_addr; 251 } else if (!strcmp(".data", secName)) { 252 dataSecStart = shdr.sh_addr; 253 } else if (!strcmp(".bss", secName)) { 254 bssSecStart = shdr.sh_addr; 255 } 256 257 section = elf_getscn(elf, ++secIdx); 258 } 259 260 // Go through all the segments in the program, record them, and scrape 261 // out information about the text, data, and bss areas needed by other 262 // code. 263 for (int i = 0; i < ehdr.e_phnum; ++i) { 264 GElf_Phdr phdr; 265 if (gelf_getphdr(elf, i, &phdr) == 0) { 266 panic("gelf_getphdr failed for segment %d.", i); 267 } 268 269 // for now we don't care about non-loadable segments 270 if (!(phdr.p_type & PT_LOAD)) 271 continue; 272 273 // Check to see if this segment contains the bss section. 274 if (phdr.p_paddr <= bssSecStart && 275 phdr.p_paddr + phdr.p_memsz > bssSecStart && 276 phdr.p_memsz - phdr.p_filesz > 0) { 277 bss.baseAddr = phdr.p_paddr + phdr.p_filesz; 278 bss.size = phdr.p_memsz - phdr.p_filesz; 279 bss.fileImage = NULL; 280 } 281 282 // Check to see if this is the text or data segment 283 if (phdr.p_vaddr <= textSecStart && 284 phdr.p_vaddr + phdr.p_filesz > textSecStart) { 285 text.baseAddr = phdr.p_paddr; 286 text.size = phdr.p_filesz; 287 text.fileImage = fileData + phdr.p_offset; 288 } else if (phdr.p_vaddr <= dataSecStart && 289 phdr.p_vaddr + phdr.p_filesz > dataSecStart) { 290 data.baseAddr = phdr.p_paddr; 291 data.size = phdr.p_filesz; 292 data.fileImage = fileData + phdr.p_offset; 293 } else { 294 // If it's none of the above but is loadable, 295 // load the filesize worth of data 296 Segment extra; 297 extra.baseAddr = phdr.p_paddr; 298 extra.size = phdr.p_filesz; 299 extra.fileImage = fileData + phdr.p_offset; 300 extraSegments.push_back(extra); 301 } 302 } 303 304 // should have found at least one loadable segment 305 assert(text.size != 0); 306 307 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", 308 text.baseAddr, text.size, data.baseAddr, data.size, 309 bss.baseAddr, bss.size); 310 311 elf_end(elf); 312 313 // We will actually read the sections when we need to load them 314} 315 316 317bool 318ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding) 319{ 320 Elf *elf; 321 int sec_idx = 1; // there is a 0 but it is nothing, go figure 322 Elf_Scn *section; 323 GElf_Shdr shdr; 324 Elf_Data *data; 325 int count, ii; 326 bool found = false; 327 GElf_Sym sym; 328 329 if (!symtab) 330 return false; 331 332 // check that header matches library version 333 if (elf_version(EV_CURRENT) == EV_NONE) 334 panic("wrong elf version number!"); 335 336 // get a pointer to elf structure 337 elf = elf_memory((char*)fileData,len); 338 339 assert(elf != NULL); 340 341 // Get the first section 342 section = elf_getscn(elf, sec_idx); 343 344 // While there are no more sections 345 while (section != NULL) { 346 gelf_getshdr(section, &shdr); 347 348 if (shdr.sh_type == SHT_SYMTAB) { 349 found = true; 350 data = elf_getdata(section, NULL); 351 count = shdr.sh_size / shdr.sh_entsize; 352 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); 353 354 // loop through all the symbols, only loading global ones 355 for (ii = 0; ii < count; ++ii) { 356 gelf_getsym(data, ii, &sym); 357 if (GELF_ST_BIND(sym.st_info) == binding) { 358 symtab->insert(sym.st_value, 359 elf_strptr(elf, shdr.sh_link, sym.st_name)); 360 } 361 } 362 } 363 ++sec_idx; 364 section = elf_getscn(elf, sec_idx); 365 } 366 367 elf_end(elf); 368 369 return found; 370} 371 372bool 373ElfObject::loadGlobalSymbols(SymbolTable *symtab, Addr addrMask) 374{ 375 return loadSomeSymbols(symtab, STB_GLOBAL); 376} 377 378bool 379ElfObject::loadLocalSymbols(SymbolTable *symtab, Addr addrMask) 380{ 381 return loadSomeSymbols(symtab, STB_LOCAL); 382} 383 384bool 385ElfObject::loadSections(Port *memPort, Addr addrMask) 386{ 387 if (!ObjectFile::loadSections(memPort, addrMask)) 388 return false; 389 390 vector<Segment>::iterator extraIt; 391 for (extraIt = extraSegments.begin(); 392 extraIt != extraSegments.end(); extraIt++) { 393 if (!loadSection(&(*extraIt), memPort, addrMask)) { 394 return false; 395 } 396 } 397 return true; 398} 399 400void 401ElfObject::getSections() 402{ 403 Elf *elf; 404 int sec_idx = 1; // there is a 0 but it is nothing, go figure 405 Elf_Scn *section; 406 GElf_Shdr shdr; 407 408 GElf_Ehdr ehdr; 409 410 assert(!sectionNames.size()); 411 412 // check that header matches library version 413 if (elf_version(EV_CURRENT) == EV_NONE) 414 panic("wrong elf version number!"); 415 416 // get a pointer to elf structure 417 elf = elf_memory((char*)fileData,len); 418 assert(elf != NULL); 419 420 // Check that we actually have a elf file 421 if (gelf_getehdr(elf, &ehdr) ==0) { 422 panic("Not ELF, shouldn't be here"); 423 } 424 425 // Get the first section 426 section = elf_getscn(elf, sec_idx); 427 428 // While there are no more sections 429 while (section != NULL) { 430 gelf_getshdr(section, &shdr); 431 sectionNames.insert(elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)); 432 section = elf_getscn(elf, ++sec_idx); 433 } // while sections 434} 435 436bool 437ElfObject::sectionExists(string sec) 438{ 439 if (!sectionNames.size()) 440 getSections(); 441 return sectionNames.find(sec) != sectionNames.end(); 442} 443 444 445