elf_object.cc revision 10360:919c02740209
1/* 2 * Copyright (c) 2011-2013 ARM Limited 3 * All rights reserved 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2003-2005 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Steve Reinhardt 41 * Ali Saidi 42 */ 43 44#include <cassert> 45#include <string> 46 47#include "base/loader/elf_object.hh" 48#include "base/loader/symtab.hh" 49#include "base/bitfield.hh" 50#include "base/misc.hh" 51#include "base/trace.hh" 52#include "debug/Loader.hh" 53#include "sim/byteswap.hh" 54#include "gelf.h" 55 56using namespace std; 57 58ObjectFile * 59ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data) 60{ 61 Elf *elf; 62 GElf_Ehdr ehdr; 63 Arch arch = UnknownArch; 64 OpSys opSys = UnknownOpSys; 65 66 // check that header matches library version 67 if (elf_version(EV_CURRENT) == EV_NONE) 68 panic("wrong elf version number!"); 69 70 // get a pointer to elf structure 71 elf = elf_memory((char*)data,len); 72 // will only fail if fd is invalid 73 assert(elf != NULL); 74 75 // Check that we actually have a elf file 76 if (gelf_getehdr(elf, &ehdr) == 0) { 77 DPRINTFR(Loader, "Not ELF\n"); 78 elf_end(elf); 79 return NULL; 80 } else { 81 //Detect the architecture 82 //Since we don't know how to check for alpha right now, we'll 83 //just assume if it wasn't something else and it's 64 bit, that's 84 //what it must be. 85 if (ehdr.e_machine == EM_SPARC64 || 86 (ehdr.e_machine == EM_SPARC && 87 ehdr.e_ident[EI_CLASS] == ELFCLASS64)|| 88 ehdr.e_machine == EM_SPARCV9) { 89 arch = ObjectFile::SPARC64; 90 } else if (ehdr.e_machine == EM_SPARC32PLUS || 91 (ehdr.e_machine == EM_SPARC && 92 ehdr.e_ident[EI_CLASS] == ELFCLASS32)) { 93 arch = ObjectFile::SPARC32; 94 } else if (ehdr.e_machine == EM_MIPS 95 && ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 96 if (ehdr.e_ident[EI_DATA] == ELFDATA2LSB) { 97 arch = ObjectFile::Mips; 98 } else { 99 fatal("The binary you're trying to load is compiled for big " 100 "endian MIPS. M5\nonly supports little endian MIPS. " 101 "Please recompile your binary.\n"); 102 } 103 } else if (ehdr.e_machine == EM_X86_64 && 104 ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 105 arch = ObjectFile::X86_64; 106 } else if (ehdr.e_machine == EM_386 && 107 ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 108 arch = ObjectFile::I386; 109 } else if (ehdr.e_machine == EM_ARM && 110 ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 111 if (bits(ehdr.e_entry, 0)) { 112 arch = ObjectFile::Thumb; 113 } else { 114 arch = ObjectFile::Arm; 115 } 116 } else if ((ehdr.e_machine == EM_AARCH64) && 117 ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 118 arch = ObjectFile::Arm64; 119 } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 120 arch = ObjectFile::Alpha; 121 } else if (ehdr.e_machine == EM_PPC && 122 ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 123 if (ehdr.e_ident[EI_DATA] == ELFDATA2MSB) { 124 arch = ObjectFile::Power; 125 } else { 126 fatal("The binary you're trying to load is compiled for " 127 "little endian Power.\nM5 only supports big " 128 "endian Power. Please recompile your binary.\n"); 129 } 130 } else if (ehdr.e_machine == EM_PPC64) { 131 fatal("The binary you're trying to load is compiled for 64-bit " 132 "Power. M5\n only supports 32-bit Power. Please " 133 "recompile your binary.\n"); 134 } else { 135 warn("Unknown architecture: %d\n", ehdr.e_machine); 136 arch = ObjectFile::UnknownArch; 137 } 138 139 //Detect the operating system 140 switch (ehdr.e_ident[EI_OSABI]) { 141 case ELFOSABI_LINUX: 142 opSys = ObjectFile::Linux; 143 break; 144 case ELFOSABI_SOLARIS: 145 opSys = ObjectFile::Solaris; 146 break; 147 case ELFOSABI_TRU64: 148 opSys = ObjectFile::Tru64; 149 break; 150 case ELFOSABI_ARM: 151 opSys = ObjectFile::LinuxArmOABI; 152 break; 153 default: 154 opSys = ObjectFile::UnknownOpSys; 155 } 156 157 //take a look at the .note.ABI section 158 //It can let us know what's what. 159 if (opSys == ObjectFile::UnknownOpSys) { 160 Elf_Scn *section; 161 GElf_Shdr shdr; 162 Elf_Data *data; 163 uint32_t osAbi;; 164 int secIdx = 1; 165 166 // Get the first section 167 section = elf_getscn(elf, secIdx); 168 169 // While there are no more sections 170 while (section != NULL && opSys == ObjectFile::UnknownOpSys) { 171 gelf_getshdr(section, &shdr); 172 if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag", 173 elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) { 174 // we have found a ABI note section 175 // Check the 5th 32bit word for OS 0 == linux, 1 == hurd, 176 // 2 == solaris, 3 == freebsd 177 data = elf_rawdata(section, NULL); 178 assert(data->d_buf); 179 if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB) 180 osAbi = htole(((uint32_t*)data->d_buf)[4]); 181 else 182 osAbi = htobe(((uint32_t*)data->d_buf)[4]); 183 184 switch(osAbi) { 185 case 0: 186 opSys = ObjectFile::Linux; 187 break; 188 case 2: 189 opSys = ObjectFile::Solaris; 190 break; 191 } 192 } // if section found 193 if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 194 opSys = ObjectFile::Solaris; 195 if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 196 opSys = ObjectFile::Solaris; 197 198 section = elf_getscn(elf, ++secIdx); 199 } // while sections 200 } 201 202 ElfObject * result = new ElfObject(fname, fd, len, data, arch, opSys); 203 204 //The number of headers in the file 205 result->_programHeaderCount = ehdr.e_phnum; 206 //Record the size of each entry 207 result->_programHeaderSize = ehdr.e_phentsize; 208 if(result->_programHeaderCount) //If there is a program header table 209 { 210 //Figure out the virtual address of the header table in the 211 //final memory image. We use the program headers themselves 212 //to translate from a file offset to the address in the image. 213 GElf_Phdr phdr; 214 uint64_t e_phoff = ehdr.e_phoff; 215 result->_programHeaderTable = 0; 216 for(int hdrnum = 0; hdrnum < result->_programHeaderCount; hdrnum++) 217 { 218 gelf_getphdr(elf, hdrnum, &phdr); 219 //Check if we've found the segment with the headers in it 220 if(phdr.p_offset <= e_phoff && 221 phdr.p_offset + phdr.p_filesz > e_phoff) 222 { 223 result->_programHeaderTable = 224 phdr.p_paddr + (e_phoff - phdr.p_offset); 225 break; 226 } 227 } 228 } 229 else 230 result->_programHeaderTable = 0; 231 232 233 elf_end(elf); 234 return result; 235 } 236} 237 238 239ElfObject::ElfObject(const string &_filename, int _fd, 240 size_t _len, uint8_t *_data, 241 Arch _arch, OpSys _opSys) 242 : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys), 243 _programHeaderTable(0), _programHeaderSize(0), _programHeaderCount(0) 244 245{ 246 Elf *elf; 247 GElf_Ehdr ehdr; 248 249 // check that header matches library version 250 if (elf_version(EV_CURRENT) == EV_NONE) 251 panic("wrong elf version number!"); 252 253 // get a pointer to elf structure 254 elf = elf_memory((char*)fileData,len); 255 // will only fail if fd is invalid 256 assert(elf != NULL); 257 258 // Check that we actually have a elf file 259 if (gelf_getehdr(elf, &ehdr) ==0) { 260 panic("Not ELF, shouldn't be here"); 261 } 262 263 entry = ehdr.e_entry; 264 265 // initialize segment sizes to 0 in case they're not present 266 text.size = data.size = bss.size = 0; 267 text.baseAddr = data.baseAddr = bss.baseAddr = 0; 268 269 int secIdx = 1; 270 Elf_Scn *section; 271 GElf_Shdr shdr; 272 273 // The first address of some important sections. 274 Addr textSecStart = 0; 275 Addr dataSecStart = 0; 276 Addr bssSecStart = 0; 277 278 // Get the first section 279 section = elf_getscn(elf, secIdx); 280 281 // Find the beginning of the most interesting sections. 282 while (section != NULL) { 283 gelf_getshdr(section, &shdr); 284 char * secName = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name); 285 286 if (secName) { 287 if (!strcmp(".text", secName)) { 288 textSecStart = shdr.sh_addr; 289 } else if (!strcmp(".data", secName)) { 290 dataSecStart = shdr.sh_addr; 291 } else if (!strcmp(".bss", secName)) { 292 bssSecStart = shdr.sh_addr; 293 } 294 } else { 295 Elf_Error errorNum = (Elf_Error)elf_errno(); 296 if (errorNum != ELF_E_NONE) { 297 const char *errorMessage = elf_errmsg(errorNum); 298 fatal("Error from libelf: %s.\n", errorMessage); 299 } 300 } 301 302 section = elf_getscn(elf, ++secIdx); 303 } 304 305 // Go through all the segments in the program, record them, and scrape 306 // out information about the text, data, and bss areas needed by other 307 // code. 308 for (int i = 0; i < ehdr.e_phnum; ++i) { 309 GElf_Phdr phdr; 310 if (gelf_getphdr(elf, i, &phdr) == 0) { 311 panic("gelf_getphdr failed for segment %d.", i); 312 } 313 314 // for now we don't care about non-loadable segments 315 if (!(phdr.p_type & PT_LOAD)) 316 continue; 317 318 // Check to see if this segment contains the bss section. 319 if (phdr.p_paddr <= bssSecStart && 320 phdr.p_paddr + phdr.p_memsz > bssSecStart && 321 phdr.p_memsz - phdr.p_filesz > 0) { 322 bss.baseAddr = phdr.p_paddr + phdr.p_filesz; 323 bss.size = phdr.p_memsz - phdr.p_filesz; 324 bss.fileImage = NULL; 325 } 326 327 // Check to see if this is the text or data segment 328 if (phdr.p_vaddr <= textSecStart && 329 phdr.p_vaddr + phdr.p_filesz > textSecStart) { 330 text.baseAddr = phdr.p_paddr; 331 text.size = phdr.p_filesz; 332 text.fileImage = fileData + phdr.p_offset; 333 } else if (phdr.p_vaddr <= dataSecStart && 334 phdr.p_vaddr + phdr.p_filesz > dataSecStart) { 335 data.baseAddr = phdr.p_paddr; 336 data.size = phdr.p_filesz; 337 data.fileImage = fileData + phdr.p_offset; 338 } else { 339 // If it's none of the above but is loadable, 340 // load the filesize worth of data 341 Segment extra; 342 extra.baseAddr = phdr.p_paddr; 343 extra.size = phdr.p_filesz; 344 extra.fileImage = fileData + phdr.p_offset; 345 extraSegments.push_back(extra); 346 } 347 } 348 349 // should have found at least one loadable segment 350 assert(text.size != 0); 351 352 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", 353 text.baseAddr, text.size, data.baseAddr, data.size, 354 bss.baseAddr, bss.size); 355 356 elf_end(elf); 357 358 // We will actually read the sections when we need to load them 359} 360 361 362bool 363ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding, Addr mask) 364{ 365 Elf *elf; 366 int sec_idx = 1; // there is a 0 but it is nothing, go figure 367 Elf_Scn *section; 368 GElf_Shdr shdr; 369 Elf_Data *data; 370 int count, ii; 371 bool found = false; 372 GElf_Sym sym; 373 374 if (!symtab) 375 return false; 376 377 // check that header matches library version 378 if (elf_version(EV_CURRENT) == EV_NONE) 379 panic("wrong elf version number!"); 380 381 // get a pointer to elf structure 382 elf = elf_memory((char*)fileData,len); 383 384 assert(elf != NULL); 385 386 // Get the first section 387 section = elf_getscn(elf, sec_idx); 388 389 // While there are no more sections 390 while (section != NULL) { 391 gelf_getshdr(section, &shdr); 392 393 if (shdr.sh_type == SHT_SYMTAB) { 394 found = true; 395 data = elf_getdata(section, NULL); 396 count = shdr.sh_size / shdr.sh_entsize; 397 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); 398 399 // loop through all the symbols, only loading global ones 400 for (ii = 0; ii < count; ++ii) { 401 gelf_getsym(data, ii, &sym); 402 if (GELF_ST_BIND(sym.st_info) == binding) { 403 char *sym_name = elf_strptr(elf, shdr.sh_link, sym.st_name); 404 if (sym_name && sym_name[0] != '$') { 405 DPRINTF(Loader, "Symbol: %-40s value %#x\n", 406 sym_name, sym.st_value); 407 symtab->insert(sym.st_value & mask, sym_name); 408 } 409 } 410 } 411 } 412 ++sec_idx; 413 section = elf_getscn(elf, sec_idx); 414 } 415 416 elf_end(elf); 417 418 return found; 419} 420 421bool 422ElfObject::loadGlobalSymbols(SymbolTable *symtab, Addr addrMask) 423{ 424 return loadSomeSymbols(symtab, STB_GLOBAL, addrMask); 425} 426 427bool 428ElfObject::loadLocalSymbols(SymbolTable *symtab, Addr addrMask) 429{ 430 bool found_local = loadSomeSymbols(symtab, STB_LOCAL, addrMask); 431 bool found_weak = loadSomeSymbols(symtab, STB_WEAK, addrMask); 432 return found_local || found_weak; 433} 434 435bool 436ElfObject::loadWeakSymbols(SymbolTable *symtab, Addr addrMask) 437{ 438 return loadSomeSymbols(symtab, STB_WEAK, addrMask); 439} 440 441bool 442ElfObject::loadSections(PortProxy& memProxy, Addr addrMask, Addr offset) 443{ 444 if (!ObjectFile::loadSections(memProxy, addrMask, offset)) 445 return false; 446 447 vector<Segment>::iterator extraIt; 448 for (extraIt = extraSegments.begin(); 449 extraIt != extraSegments.end(); extraIt++) { 450 if (!loadSection(&(*extraIt), memProxy, addrMask, offset)) { 451 return false; 452 } 453 } 454 return true; 455} 456 457void 458ElfObject::getSections() 459{ 460 Elf *elf; 461 int sec_idx = 1; // there is a 0 but it is nothing, go figure 462 Elf_Scn *section; 463 GElf_Shdr shdr; 464 465 GElf_Ehdr ehdr; 466 467 assert(!sectionNames.size()); 468 469 // check that header matches library version 470 if (elf_version(EV_CURRENT) == EV_NONE) 471 panic("wrong elf version number!"); 472 473 // get a pointer to elf structure 474 elf = elf_memory((char*)fileData,len); 475 assert(elf != NULL); 476 477 // Check that we actually have a elf file 478 if (gelf_getehdr(elf, &ehdr) ==0) { 479 panic("Not ELF, shouldn't be here"); 480 } 481 482 // Get the first section 483 section = elf_getscn(elf, sec_idx); 484 485 // While there are no more sections 486 while (section != NULL) { 487 gelf_getshdr(section, &shdr); 488 sectionNames.insert(elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)); 489 section = elf_getscn(elf, ++sec_idx); 490 } // while sections 491} 492 493bool 494ElfObject::sectionExists(string sec) 495{ 496 if (!sectionNames.size()) 497 getSections(); 498 return sectionNames.find(sec) != sectionNames.end(); 499} 500 501 502