elf_object.cc revision 10037:5cac77888310
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) 243 244{ 245 Elf *elf; 246 GElf_Ehdr ehdr; 247 248 // check that header matches library version 249 if (elf_version(EV_CURRENT) == EV_NONE) 250 panic("wrong elf version number!"); 251 252 // get a pointer to elf structure 253 elf = elf_memory((char*)fileData,len); 254 // will only fail if fd is invalid 255 assert(elf != NULL); 256 257 // Check that we actually have a elf file 258 if (gelf_getehdr(elf, &ehdr) ==0) { 259 panic("Not ELF, shouldn't be here"); 260 } 261 262 entry = ehdr.e_entry; 263 264 // initialize segment sizes to 0 in case they're not present 265 text.size = data.size = bss.size = 0; 266 text.baseAddr = data.baseAddr = bss.baseAddr = 0; 267 268 int secIdx = 1; 269 Elf_Scn *section; 270 GElf_Shdr shdr; 271 272 // The first address of some important sections. 273 Addr textSecStart = 0; 274 Addr dataSecStart = 0; 275 Addr bssSecStart = 0; 276 277 // Get the first section 278 section = elf_getscn(elf, secIdx); 279 280 // Find the beginning of the most interesting sections. 281 while (section != NULL) { 282 gelf_getshdr(section, &shdr); 283 char * secName = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name); 284 285 if (secName) { 286 if (!strcmp(".text", secName)) { 287 textSecStart = shdr.sh_addr; 288 } else if (!strcmp(".data", secName)) { 289 dataSecStart = shdr.sh_addr; 290 } else if (!strcmp(".bss", secName)) { 291 bssSecStart = shdr.sh_addr; 292 } 293 } else { 294 Elf_Error errorNum = (Elf_Error)elf_errno(); 295 if (errorNum != ELF_E_NONE) { 296 const char *errorMessage = elf_errmsg(errorNum); 297 fatal("Error from libelf: %s.\n", errorMessage); 298 } 299 } 300 301 section = elf_getscn(elf, ++secIdx); 302 } 303 304 // Go through all the segments in the program, record them, and scrape 305 // out information about the text, data, and bss areas needed by other 306 // code. 307 for (int i = 0; i < ehdr.e_phnum; ++i) { 308 GElf_Phdr phdr; 309 if (gelf_getphdr(elf, i, &phdr) == 0) { 310 panic("gelf_getphdr failed for segment %d.", i); 311 } 312 313 // for now we don't care about non-loadable segments 314 if (!(phdr.p_type & PT_LOAD)) 315 continue; 316 317 // Check to see if this segment contains the bss section. 318 if (phdr.p_paddr <= bssSecStart && 319 phdr.p_paddr + phdr.p_memsz > bssSecStart && 320 phdr.p_memsz - phdr.p_filesz > 0) { 321 bss.baseAddr = phdr.p_paddr + phdr.p_filesz; 322 bss.size = phdr.p_memsz - phdr.p_filesz; 323 bss.fileImage = NULL; 324 } 325 326 // Check to see if this is the text or data segment 327 if (phdr.p_vaddr <= textSecStart && 328 phdr.p_vaddr + phdr.p_filesz > textSecStart) { 329 text.baseAddr = phdr.p_paddr; 330 text.size = phdr.p_filesz; 331 text.fileImage = fileData + phdr.p_offset; 332 } else if (phdr.p_vaddr <= dataSecStart && 333 phdr.p_vaddr + phdr.p_filesz > dataSecStart) { 334 data.baseAddr = phdr.p_paddr; 335 data.size = phdr.p_filesz; 336 data.fileImage = fileData + phdr.p_offset; 337 } else { 338 // If it's none of the above but is loadable, 339 // load the filesize worth of data 340 Segment extra; 341 extra.baseAddr = phdr.p_paddr; 342 extra.size = phdr.p_filesz; 343 extra.fileImage = fileData + phdr.p_offset; 344 extraSegments.push_back(extra); 345 } 346 } 347 348 // should have found at least one loadable segment 349 assert(text.size != 0); 350 351 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", 352 text.baseAddr, text.size, data.baseAddr, data.size, 353 bss.baseAddr, bss.size); 354 355 elf_end(elf); 356 357 // We will actually read the sections when we need to load them 358} 359 360 361bool 362ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding, Addr mask) 363{ 364 Elf *elf; 365 int sec_idx = 1; // there is a 0 but it is nothing, go figure 366 Elf_Scn *section; 367 GElf_Shdr shdr; 368 Elf_Data *data; 369 int count, ii; 370 bool found = false; 371 GElf_Sym sym; 372 373 if (!symtab) 374 return false; 375 376 // check that header matches library version 377 if (elf_version(EV_CURRENT) == EV_NONE) 378 panic("wrong elf version number!"); 379 380 // get a pointer to elf structure 381 elf = elf_memory((char*)fileData,len); 382 383 assert(elf != NULL); 384 385 // Get the first section 386 section = elf_getscn(elf, sec_idx); 387 388 // While there are no more sections 389 while (section != NULL) { 390 gelf_getshdr(section, &shdr); 391 392 if (shdr.sh_type == SHT_SYMTAB) { 393 found = true; 394 data = elf_getdata(section, NULL); 395 count = shdr.sh_size / shdr.sh_entsize; 396 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); 397 398 // loop through all the symbols, only loading global ones 399 for (ii = 0; ii < count; ++ii) { 400 gelf_getsym(data, ii, &sym); 401 if (GELF_ST_BIND(sym.st_info) == binding) { 402 char *sym_name = elf_strptr(elf, shdr.sh_link, sym.st_name); 403 if (sym_name && sym_name[0] != '$') { 404 DPRINTF(Loader, "Symbol: %-40s value %#x\n", 405 sym_name, sym.st_value); 406 symtab->insert(sym.st_value & mask, sym_name); 407 } 408 } 409 } 410 } 411 ++sec_idx; 412 section = elf_getscn(elf, sec_idx); 413 } 414 415 elf_end(elf); 416 417 return found; 418} 419 420bool 421ElfObject::loadGlobalSymbols(SymbolTable *symtab, Addr addrMask) 422{ 423 return loadSomeSymbols(symtab, STB_GLOBAL, addrMask); 424} 425 426bool 427ElfObject::loadLocalSymbols(SymbolTable *symtab, Addr addrMask) 428{ 429 bool found_local = loadSomeSymbols(symtab, STB_LOCAL, addrMask); 430 bool found_weak = loadSomeSymbols(symtab, STB_WEAK, addrMask); 431 return found_local || found_weak; 432} 433 434bool 435ElfObject::loadWeakSymbols(SymbolTable *symtab, Addr addrMask) 436{ 437 return loadSomeSymbols(symtab, STB_WEAK, addrMask); 438} 439 440bool 441ElfObject::loadSections(PortProxy& memProxy, Addr addrMask, Addr offset) 442{ 443 if (!ObjectFile::loadSections(memProxy, addrMask, offset)) 444 return false; 445 446 vector<Segment>::iterator extraIt; 447 for (extraIt = extraSegments.begin(); 448 extraIt != extraSegments.end(); extraIt++) { 449 if (!loadSection(&(*extraIt), memProxy, addrMask, offset)) { 450 return false; 451 } 452 } 453 return true; 454} 455 456void 457ElfObject::getSections() 458{ 459 Elf *elf; 460 int sec_idx = 1; // there is a 0 but it is nothing, go figure 461 Elf_Scn *section; 462 GElf_Shdr shdr; 463 464 GElf_Ehdr ehdr; 465 466 assert(!sectionNames.size()); 467 468 // check that header matches library version 469 if (elf_version(EV_CURRENT) == EV_NONE) 470 panic("wrong elf version number!"); 471 472 // get a pointer to elf structure 473 elf = elf_memory((char*)fileData,len); 474 assert(elf != NULL); 475 476 // Check that we actually have a elf file 477 if (gelf_getehdr(elf, &ehdr) ==0) { 478 panic("Not ELF, shouldn't be here"); 479 } 480 481 // Get the first section 482 section = elf_getscn(elf, sec_idx); 483 484 // While there are no more sections 485 while (section != NULL) { 486 gelf_getshdr(section, &shdr); 487 sectionNames.insert(elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)); 488 section = elf_getscn(elf, ++sec_idx); 489 } // while sections 490} 491 492bool 493ElfObject::sectionExists(string sec) 494{ 495 if (!sectionNames.size()) 496 getSections(); 497 return sectionNames.find(sec) != sectionNames.end(); 498} 499 500 501