elf_object.cc revision 9641:2285b98847d7
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 "base/loader/elf_object.hh" 36#include "base/loader/symtab.hh" 37#include "base/bitfield.hh" 38#include "base/misc.hh" 39#include "base/trace.hh" 40#include "debug/Loader.hh" 41#include "sim/byteswap.hh" 42#include "gelf.h" 43 44using namespace std; 45 46ObjectFile * 47ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data) 48{ 49 Elf *elf; 50 GElf_Ehdr ehdr; 51 Arch arch = UnknownArch; 52 OpSys opSys = UnknownOpSys; 53 54 // check that header matches library version 55 if (elf_version(EV_CURRENT) == EV_NONE) 56 panic("wrong elf version number!"); 57 58 // get a pointer to elf structure 59 elf = elf_memory((char*)data,len); 60 // will only fail if fd is invalid 61 assert(elf != NULL); 62 63 // Check that we actually have a elf file 64 if (gelf_getehdr(elf, &ehdr) ==0) { 65 DPRINTFR(Loader, "Not ELF\n"); 66 elf_end(elf); 67 return NULL; 68 } else { 69 //Detect the architecture 70 //Since we don't know how to check for alpha right now, we'll 71 //just assume if it wasn't something else and it's 64 bit, that's 72 //what it must be. 73 if (ehdr.e_machine == EM_SPARC64 || 74 (ehdr.e_machine == EM_SPARC && 75 ehdr.e_ident[EI_CLASS] == ELFCLASS64)|| 76 ehdr.e_machine == EM_SPARCV9) { 77 arch = ObjectFile::SPARC64; 78 } else if (ehdr.e_machine == EM_SPARC32PLUS || 79 (ehdr.e_machine == EM_SPARC && 80 ehdr.e_ident[EI_CLASS] == ELFCLASS32)) { 81 arch = ObjectFile::SPARC32; 82 } else if (ehdr.e_machine == EM_MIPS 83 && ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 84 if (ehdr.e_ident[EI_DATA] == ELFDATA2LSB) { 85 arch = ObjectFile::Mips; 86 } else { 87 fatal("The binary you're trying to load is compiled for big " 88 "endian MIPS. M5\nonly supports little endian MIPS. " 89 "Please recompile your binary.\n"); 90 } 91 } else if (ehdr.e_machine == EM_X86_64 && 92 ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 93 arch = ObjectFile::X86_64; 94 } else if (ehdr.e_machine == EM_386 && 95 ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 96 arch = ObjectFile::I386; 97 } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 98 arch = ObjectFile::Alpha; 99 } else if (ehdr.e_machine == EM_ARM) { 100 if (bits(ehdr.e_entry, 0)) { 101 arch = ObjectFile::Thumb; 102 } else { 103 arch = ObjectFile::Arm; 104 } 105 } else if (ehdr.e_machine == EM_PPC && 106 ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 107 if (ehdr.e_ident[EI_DATA] == ELFDATA2MSB) { 108 arch = ObjectFile::Power; 109 } else { 110 fatal("The binary you're trying to load is compiled for " 111 "little endian Power.\nM5 only supports big " 112 "endian Power. Please recompile your binary.\n"); 113 } 114 } else if (ehdr.e_machine == EM_PPC64) { 115 fatal("The binary you're trying to load is compiled for 64-bit " 116 "Power. M5\n only supports 32-bit Power. Please " 117 "recompile your binary.\n"); 118 } else { 119 warn("Unknown architecture: %d\n", ehdr.e_machine); 120 arch = ObjectFile::UnknownArch; 121 } 122 123 //Detect the operating system 124 switch (ehdr.e_ident[EI_OSABI]) 125 { 126 127 case ELFOSABI_LINUX: 128 opSys = ObjectFile::Linux; 129 break; 130 case ELFOSABI_SOLARIS: 131 opSys = ObjectFile::Solaris; 132 break; 133 case ELFOSABI_TRU64: 134 opSys = ObjectFile::Tru64; 135 break; 136 case ELFOSABI_ARM: 137 opSys = ObjectFile::LinuxArmOABI; 138 break; 139 default: 140 opSys = ObjectFile::UnknownOpSys; 141 } 142 143 //take a look at the .note.ABI section 144 //It can let us know what's what. 145 if (opSys == ObjectFile::UnknownOpSys) { 146 Elf_Scn *section; 147 GElf_Shdr shdr; 148 Elf_Data *data; 149 uint32_t osAbi;; 150 int secIdx = 1; 151 152 // Get the first section 153 section = elf_getscn(elf, secIdx); 154 155 // While there are no more sections 156 while (section != NULL && opSys == ObjectFile::UnknownOpSys) { 157 gelf_getshdr(section, &shdr); 158 if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag", 159 elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) { 160 // we have found a ABI note section 161 // Check the 5th 32bit word for OS 0 == linux, 1 == hurd, 162 // 2 == solaris, 3 == freebsd 163 data = elf_rawdata(section, NULL); 164 assert(data->d_buf); 165 if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB) 166 osAbi = htole(((uint32_t*)data->d_buf)[4]); 167 else 168 osAbi = htobe(((uint32_t*)data->d_buf)[4]); 169 170 switch(osAbi) { 171 case 0: 172 opSys = ObjectFile::Linux; 173 break; 174 case 2: 175 opSys = ObjectFile::Solaris; 176 break; 177 } 178 } // if section found 179 if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 180 opSys = ObjectFile::Solaris; 181 if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 182 opSys = ObjectFile::Solaris; 183 184 section = elf_getscn(elf, ++secIdx); 185 } // while sections 186 } 187 188 ElfObject * result = new ElfObject(fname, fd, len, data, arch, opSys); 189 190 //The number of headers in the file 191 result->_programHeaderCount = ehdr.e_phnum; 192 //Record the size of each entry 193 result->_programHeaderSize = ehdr.e_phentsize; 194 if(result->_programHeaderCount) //If there is a program header table 195 { 196 //Figure out the virtual address of the header table in the 197 //final memory image. We use the program headers themselves 198 //to translate from a file offset to the address in the image. 199 GElf_Phdr phdr; 200 uint64_t e_phoff = ehdr.e_phoff; 201 result->_programHeaderTable = 0; 202 for(int hdrnum = 0; hdrnum < result->_programHeaderCount; hdrnum++) 203 { 204 gelf_getphdr(elf, hdrnum, &phdr); 205 //Check if we've found the segment with the headers in it 206 if(phdr.p_offset <= e_phoff && 207 phdr.p_offset + phdr.p_filesz > e_phoff) 208 { 209 result->_programHeaderTable = phdr.p_paddr + e_phoff; 210 break; 211 } 212 } 213 } 214 else 215 result->_programHeaderTable = 0; 216 217 218 elf_end(elf); 219 return result; 220 } 221} 222 223 224ElfObject::ElfObject(const string &_filename, int _fd, 225 size_t _len, uint8_t *_data, 226 Arch _arch, OpSys _opSys) 227 : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys) 228 229{ 230 Elf *elf; 231 GElf_Ehdr ehdr; 232 233 // check that header matches library version 234 if (elf_version(EV_CURRENT) == EV_NONE) 235 panic("wrong elf version number!"); 236 237 // get a pointer to elf structure 238 elf = elf_memory((char*)fileData,len); 239 // will only fail if fd is invalid 240 assert(elf != NULL); 241 242 // Check that we actually have a elf file 243 if (gelf_getehdr(elf, &ehdr) ==0) { 244 panic("Not ELF, shouldn't be here"); 245 } 246 247 entry = ehdr.e_entry; 248 249 // initialize segment sizes to 0 in case they're not present 250 text.size = data.size = bss.size = 0; 251 text.baseAddr = data.baseAddr = bss.baseAddr = 0; 252 253 int secIdx = 1; 254 Elf_Scn *section; 255 GElf_Shdr shdr; 256 257 // The first address of some important sections. 258 Addr textSecStart = 0; 259 Addr dataSecStart = 0; 260 Addr bssSecStart = 0; 261 262 // Get the first section 263 section = elf_getscn(elf, secIdx); 264 265 // Find the beginning of the most interesting sections. 266 while (section != NULL) { 267 gelf_getshdr(section, &shdr); 268 char * secName = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name); 269 270 if (secName) { 271 if (!strcmp(".text", secName)) { 272 textSecStart = shdr.sh_addr; 273 } else if (!strcmp(".data", secName)) { 274 dataSecStart = shdr.sh_addr; 275 } else if (!strcmp(".bss", secName)) { 276 bssSecStart = shdr.sh_addr; 277 } 278 } else { 279 Elf_Error errorNum = (Elf_Error)elf_errno(); 280 if (errorNum != ELF_E_NONE) { 281 const char *errorMessage = elf_errmsg(errorNum); 282 fatal("Error from libelf: %s.\n", errorMessage); 283 } 284 } 285 286 section = elf_getscn(elf, ++secIdx); 287 } 288 289 // Go through all the segments in the program, record them, and scrape 290 // out information about the text, data, and bss areas needed by other 291 // code. 292 for (int i = 0; i < ehdr.e_phnum; ++i) { 293 GElf_Phdr phdr; 294 if (gelf_getphdr(elf, i, &phdr) == 0) { 295 panic("gelf_getphdr failed for segment %d.", i); 296 } 297 298 // for now we don't care about non-loadable segments 299 if (!(phdr.p_type & PT_LOAD)) 300 continue; 301 302 // Check to see if this segment contains the bss section. 303 if (phdr.p_paddr <= bssSecStart && 304 phdr.p_paddr + phdr.p_memsz > bssSecStart && 305 phdr.p_memsz - phdr.p_filesz > 0) { 306 bss.baseAddr = phdr.p_paddr + phdr.p_filesz; 307 bss.size = phdr.p_memsz - phdr.p_filesz; 308 bss.fileImage = NULL; 309 } 310 311 // Check to see if this is the text or data segment 312 if (phdr.p_vaddr <= textSecStart && 313 phdr.p_vaddr + phdr.p_filesz > textSecStart) { 314 text.baseAddr = phdr.p_paddr; 315 text.size = phdr.p_filesz; 316 text.fileImage = fileData + phdr.p_offset; 317 } else if (phdr.p_vaddr <= dataSecStart && 318 phdr.p_vaddr + phdr.p_filesz > dataSecStart) { 319 data.baseAddr = phdr.p_paddr; 320 data.size = phdr.p_filesz; 321 data.fileImage = fileData + phdr.p_offset; 322 } else { 323 // If it's none of the above but is loadable, 324 // load the filesize worth of data 325 Segment extra; 326 extra.baseAddr = phdr.p_paddr; 327 extra.size = phdr.p_filesz; 328 extra.fileImage = fileData + phdr.p_offset; 329 extraSegments.push_back(extra); 330 } 331 } 332 333 // should have found at least one loadable segment 334 assert(text.size != 0); 335 336 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", 337 text.baseAddr, text.size, data.baseAddr, data.size, 338 bss.baseAddr, bss.size); 339 340 elf_end(elf); 341 342 // We will actually read the sections when we need to load them 343} 344 345 346bool 347ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding, Addr mask) 348{ 349 Elf *elf; 350 int sec_idx = 1; // there is a 0 but it is nothing, go figure 351 Elf_Scn *section; 352 GElf_Shdr shdr; 353 Elf_Data *data; 354 int count, ii; 355 bool found = false; 356 GElf_Sym sym; 357 358 if (!symtab) 359 return false; 360 361 // check that header matches library version 362 if (elf_version(EV_CURRENT) == EV_NONE) 363 panic("wrong elf version number!"); 364 365 // get a pointer to elf structure 366 elf = elf_memory((char*)fileData,len); 367 368 assert(elf != NULL); 369 370 // Get the first section 371 section = elf_getscn(elf, sec_idx); 372 373 // While there are no more sections 374 while (section != NULL) { 375 gelf_getshdr(section, &shdr); 376 377 if (shdr.sh_type == SHT_SYMTAB) { 378 found = true; 379 data = elf_getdata(section, NULL); 380 count = shdr.sh_size / shdr.sh_entsize; 381 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); 382 383 // loop through all the symbols, only loading global ones 384 for (ii = 0; ii < count; ++ii) { 385 gelf_getsym(data, ii, &sym); 386 if (GELF_ST_BIND(sym.st_info) == binding) { 387 char *sym_name = elf_strptr(elf, shdr.sh_link, sym.st_name); 388 if (sym_name && sym_name[0] != '$') { 389 DPRINTF(Loader, "Symbol: %-40s value %#x\n", 390 sym_name, sym.st_value); 391 symtab->insert(sym.st_value & mask, sym_name); 392 } 393 } 394 } 395 } 396 ++sec_idx; 397 section = elf_getscn(elf, sec_idx); 398 } 399 400 elf_end(elf); 401 402 return found; 403} 404 405bool 406ElfObject::loadGlobalSymbols(SymbolTable *symtab, Addr addrMask) 407{ 408 return loadSomeSymbols(symtab, STB_GLOBAL, addrMask); 409} 410 411bool 412ElfObject::loadLocalSymbols(SymbolTable *symtab, Addr addrMask) 413{ 414 return loadSomeSymbols(symtab, STB_LOCAL, addrMask); 415} 416 417bool 418ElfObject::loadWeakSymbols(SymbolTable *symtab, Addr addrMask) 419{ 420 return loadSomeSymbols(symtab, STB_WEAK, addrMask); 421} 422 423bool 424ElfObject::loadSections(PortProxy& memProxy, Addr addrMask) 425{ 426 if (!ObjectFile::loadSections(memProxy, addrMask)) 427 return false; 428 429 vector<Segment>::iterator extraIt; 430 for (extraIt = extraSegments.begin(); 431 extraIt != extraSegments.end(); extraIt++) { 432 if (!loadSection(&(*extraIt), memProxy, addrMask)) { 433 return false; 434 } 435 } 436 return true; 437} 438 439void 440ElfObject::getSections() 441{ 442 Elf *elf; 443 int sec_idx = 1; // there is a 0 but it is nothing, go figure 444 Elf_Scn *section; 445 GElf_Shdr shdr; 446 447 GElf_Ehdr ehdr; 448 449 assert(!sectionNames.size()); 450 451 // check that header matches library version 452 if (elf_version(EV_CURRENT) == EV_NONE) 453 panic("wrong elf version number!"); 454 455 // get a pointer to elf structure 456 elf = elf_memory((char*)fileData,len); 457 assert(elf != NULL); 458 459 // Check that we actually have a elf file 460 if (gelf_getehdr(elf, &ehdr) ==0) { 461 panic("Not ELF, shouldn't be here"); 462 } 463 464 // Get the first section 465 section = elf_getscn(elf, sec_idx); 466 467 // While there are no more sections 468 while (section != NULL) { 469 gelf_getshdr(section, &shdr); 470 sectionNames.insert(elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)); 471 section = elf_getscn(elf, ++sec_idx); 472 } // while sections 473} 474 475bool 476ElfObject::sectionExists(string sec) 477{ 478 if (!sectionNames.size()) 479 getSections(); 480 return sectionNames.find(sec) != sectionNames.end(); 481} 482 483 484