elf_object.cc revision 2632:1bb2f91485ea
12521SN/A/* 29814Sandreas.hansson@arm.com * Copyright (c) 2003-2005 The Regents of The University of Michigan 38706Sandreas.hansson@arm.com * All rights reserved. 48706Sandreas.hansson@arm.com * 58706Sandreas.hansson@arm.com * Redistribution and use in source and binary forms, with or without 68706Sandreas.hansson@arm.com * modification, are permitted provided that the following conditions are 78706Sandreas.hansson@arm.com * met: redistributions of source code must retain the above copyright 88706Sandreas.hansson@arm.com * notice, this list of conditions and the following disclaimer; 98706Sandreas.hansson@arm.com * redistributions in binary form must reproduce the above copyright 108706Sandreas.hansson@arm.com * notice, this list of conditions and the following disclaimer in the 118706Sandreas.hansson@arm.com * documentation and/or other materials provided with the distribution; 128706Sandreas.hansson@arm.com * neither the name of the copyright holders nor the names of its 138706Sandreas.hansson@arm.com * contributors may be used to endorse or promote products derived from 142521SN/A * this software without specific prior written permission. 152521SN/A * 162521SN/A * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 172521SN/A * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 182521SN/A * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 192521SN/A * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 202521SN/A * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 212521SN/A * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 222521SN/A * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 232521SN/A * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 242521SN/A * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 252521SN/A * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 262521SN/A * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 272521SN/A */ 282521SN/A 292521SN/A#include <string> 302521SN/A 312521SN/A// Because of the -Wundef flag we have to do this 322521SN/A#define __LIBELF_INTERNAL__ 0 332521SN/A// counterintuitive, but the flag below causes libelf to define 342521SN/A// 64-bit elf types that apparently didn't exist in some older 352521SN/A// versions of Linux. They seem to be there in 2.4.x, so don't 362521SN/A// set this now (it causes things to break on 64-bit platforms). 372521SN/A#define __LIBELF64_LINUX 0 382521SN/A#define __LIBELF_NEED_LINK_H 0 392665SN/A#define __LIBELF_SYMBOL_VERSIONS 0 402665SN/A 418706Sandreas.hansson@arm.com#include "libelf/libelf.h" 422521SN/A#include "libelf/gelf.h" 432521SN/A 442521SN/A#include "base/loader/elf_object.hh" 452982SN/A#include "base/misc.hh" 462982SN/A 472521SN/A#include "base/loader/symtab.hh" 482521SN/A 4911793Sbrandon.potter@amd.com#include "base/trace.hh" // for DPRINTF 5011793Sbrandon.potter@amd.com 519850Sandreas.hansson@arm.com#include "sim/byteswap.hh" 522521SN/A 538706Sandreas.hansson@arm.com 544070SN/Ausing namespace std; 559814Sandreas.hansson@arm.com 568706Sandreas.hansson@arm.comObjectFile * 578706Sandreas.hansson@arm.comElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data) 588706Sandreas.hansson@arm.com{ 598706Sandreas.hansson@arm.com Elf *elf; 609814Sandreas.hansson@arm.com GElf_Ehdr ehdr; 619814Sandreas.hansson@arm.com Arch arch = UnknownArch; 628706Sandreas.hansson@arm.com OpSys opSys = UnknownOpSys; 638706Sandreas.hansson@arm.com 648706Sandreas.hansson@arm.com // check that header matches library version 659814Sandreas.hansson@arm.com if (elf_version(EV_CURRENT) == EV_NONE) 669814Sandreas.hansson@arm.com panic("wrong elf version number!"); 679814Sandreas.hansson@arm.com 688706Sandreas.hansson@arm.com // get a pointer to elf structure 698706Sandreas.hansson@arm.com elf = elf_memory((char*)data,len); 708706Sandreas.hansson@arm.com // will only fail if fd is invalid 718706Sandreas.hansson@arm.com assert(elf != NULL); 728706Sandreas.hansson@arm.com 738706Sandreas.hansson@arm.com // Check that we actually have a elf file 742521SN/A if (gelf_getehdr(elf, &ehdr) ==0) { 752521SN/A DPRINTFR(Loader, "Not ELF\n"); 768861Sandreas.hansson@arm.com elf_end(elf); 772521SN/A return NULL; 782521SN/A } else { 792521SN/A //Detect the architecture 808706Sandreas.hansson@arm.com //Since we don't know how to check for alpha right now, we'll 812521SN/A //just assume if it wasn't something else and it's 64 bit, that's 828706Sandreas.hansson@arm.com //what it must be. 838706Sandreas.hansson@arm.com if (ehdr.e_machine == EM_SPARC64 || 842521SN/A ehdr.e_machine == EM_SPARC || 852521SN/A ehdr.e_machine == EM_SPARCV9) { 862521SN/A arch = ObjectFile::SPARC; 8712532Sandreas.sandberg@arm.com } else if (ehdr.e_machine == EM_MIPS 882521SN/A && ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 892521SN/A arch = ObjectFile::Mips; 902521SN/A } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 912521SN/A arch = ObjectFile::Alpha; 922521SN/A } else { 9310564Sandreas.hansson@arm.com warn("Unknown architecture: %d\n", ehdr.e_machine); 942521SN/A arch = ObjectFile::UnknownArch; 952521SN/A } 962521SN/A 978706Sandreas.hansson@arm.com //Detect the operating system 982521SN/A switch (ehdr.e_ident[EI_OSABI]) 998706Sandreas.hansson@arm.com { 1008706Sandreas.hansson@arm.com 1012521SN/A case ELFOSABI_LINUX: 1022521SN/A opSys = ObjectFile::Linux; 1032521SN/A break; 10412532Sandreas.sandberg@arm.com case ELFOSABI_SOLARIS: 1052521SN/A opSys = ObjectFile::Solaris; 1062521SN/A break; 1072521SN/A case ELFOSABI_TRU64: 1082521SN/A opSys = ObjectFile::Tru64; 1094070SN/A break; 1108861Sandreas.hansson@arm.com default: 1118706Sandreas.hansson@arm.com opSys = ObjectFile::UnknownOpSys; 1128706Sandreas.hansson@arm.com } 1138706Sandreas.hansson@arm.com 1148706Sandreas.hansson@arm.com //take a look at the .note.ABI section 1158706Sandreas.hansson@arm.com //It can let us know what's what. 1168706Sandreas.hansson@arm.com if (opSys == ObjectFile::UnknownOpSys) { 1178706Sandreas.hansson@arm.com Elf_Scn *section; 1188706Sandreas.hansson@arm.com GElf_Shdr shdr; 1198706Sandreas.hansson@arm.com Elf_Data *data; 1208706Sandreas.hansson@arm.com uint32_t osAbi;; 12112532Sandreas.sandberg@arm.com int secIdx = 1; 1228706Sandreas.hansson@arm.com 1238706Sandreas.hansson@arm.com // Get the first section 1248706Sandreas.hansson@arm.com section = elf_getscn(elf, secIdx); 1258706Sandreas.hansson@arm.com 1264070SN/A // While there are no more sections 1274070SN/A while (section != NULL && opSys == ObjectFile::UnknownOpSys) { 1284070SN/A gelf_getshdr(section, &shdr); 1298852Sandreas.hansson@arm.com if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag", 1304070SN/A elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) { 1314070SN/A // we have found a ABI note section 1324070SN/A // Check the 5th 32bit word for OS 0 == linux, 1 == hurd, 13310564Sandreas.hansson@arm.com // 2 == solaris, 3 == freebsd 1344070SN/A data = elf_rawdata(section, NULL); 1354070SN/A assert(data->d_buf); 1368852Sandreas.hansson@arm.com if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB) 1374070SN/A osAbi = htole(((uint32_t*)data->d_buf)[4]); 1384070SN/A else 1394070SN/A osAbi = htobe(((uint32_t*)data->d_buf)[4]); 1404070SN/A 1414070SN/A switch(osAbi) { 1424070SN/A case 0: 1438852Sandreas.hansson@arm.com opSys = ObjectFile::Linux; 1444070SN/A break; 1458722SMitchell.Hayenga@ARM.com case 2: 1468722SMitchell.Hayenga@ARM.com opSys = ObjectFile::Solaris; 1478852Sandreas.hansson@arm.com break; 1488996SAli.Saidi@ARM.com } 1498722SMitchell.Hayenga@ARM.com } // if section found 1508722SMitchell.Hayenga@ARM.com if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 1518722SMitchell.Hayenga@ARM.com opSys = ObjectFile::Solaris; 1524070SN/A if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 1538722SMitchell.Hayenga@ARM.com opSys = ObjectFile::Solaris; 1548722SMitchell.Hayenga@ARM.com 1554070SN/A section = elf_getscn(elf, ++secIdx); 1564070SN/A } // while sections 1574070SN/A } 15810564Sandreas.hansson@arm.com 1594070SN/A elf_end(elf); 1608852Sandreas.hansson@arm.com return new ElfObject(fname, fd, len, data, arch, opSys); 1614070SN/A } 1628852Sandreas.hansson@arm.com} 1634070SN/A 1648852Sandreas.hansson@arm.com 1654070SN/AElfObject::ElfObject(const string &_filename, int _fd, 1664070SN/A size_t _len, uint8_t *_data, 1674070SN/A Arch _arch, OpSys _opSys) 168 : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys) 169 170{ 171 Elf *elf; 172 GElf_Ehdr ehdr; 173 174 // check that header matches library version 175 if (elf_version(EV_CURRENT) == EV_NONE) 176 panic("wrong elf version number!"); 177 178 // get a pointer to elf structure 179 elf = elf_memory((char*)fileData,len); 180 // will only fail if fd is invalid 181 assert(elf != NULL); 182 183 // Check that we actually have a elf file 184 if (gelf_getehdr(elf, &ehdr) ==0) { 185 panic("Not ELF, shouldn't be here"); 186 } 187 188 entry = ehdr.e_entry; 189 190 191 // initialize segment sizes to 0 in case they're not present 192 text.size = data.size = bss.size = 0; 193 194 for (int i = 0; i < ehdr.e_phnum; ++i) { 195 GElf_Phdr phdr; 196 if (gelf_getphdr(elf, i, &phdr) == 0) { 197 panic("gelf_getphdr failed for section %d", i); 198 } 199 200 // for now we don't care about non-loadable segments 201 if (!(phdr.p_type & PT_LOAD)) 202 continue; 203 204 // the headers don't explicitly distinguish text from data, 205 // but empirically the text segment comes first. 206 if (text.size == 0) { // haven't seen text segment yet 207 text.baseAddr = phdr.p_vaddr; 208 text.size = phdr.p_filesz; 209 text.fileImage = fileData + phdr.p_offset; 210 // if there's any padding at the end that's not in the 211 // file, call it the bss. This happens in the "text" 212 // segment if there's only one loadable segment (as for 213 // kernel images). 214 bss.size = phdr.p_memsz - phdr.p_filesz; 215 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; 216 bss.fileImage = NULL; 217 } else if (data.size == 0) { // have text, this must be data 218 data.baseAddr = phdr.p_vaddr; 219 data.size = phdr.p_filesz; 220 data.fileImage = fileData + phdr.p_offset; 221 // if there's any padding at the end that's not in the 222 // file, call it the bss. Warn if this happens for both 223 // the text & data segments (should only have one bss). 224 if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) { 225 warn("Two implied bss segments in file!\n"); 226 } 227 bss.size = phdr.p_memsz - phdr.p_filesz; 228 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; 229 bss.fileImage = NULL; 230 } else { 231 warn("More than two loadable segments in ELF object."); 232 warn("Ignoring segment @ 0x%x length 0x%x.", 233 phdr.p_vaddr, phdr.p_filesz); 234 } 235 } 236 237 // should have found at least one loadable segment 238 assert(text.size != 0); 239 240 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", 241 text.baseAddr, text.size, data.baseAddr, data.size, 242 bss.baseAddr, bss.size); 243 244 elf_end(elf); 245 246 // We will actually read the sections when we need to load them 247} 248 249 250bool 251ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding) 252{ 253 Elf *elf; 254 int sec_idx = 1; // there is a 0 but it is nothing, go figure 255 Elf_Scn *section; 256 GElf_Shdr shdr; 257 Elf_Data *data; 258 int count, ii; 259 bool found = false; 260 GElf_Sym sym; 261 262 if (!symtab) 263 return false; 264 265 // check that header matches library version 266 if (elf_version(EV_CURRENT) == EV_NONE) 267 panic("wrong elf version number!"); 268 269 // get a pointer to elf structure 270 elf = elf_memory((char*)fileData,len); 271 272 assert(elf != NULL); 273 274 // Get the first section 275 section = elf_getscn(elf, sec_idx); 276 277 // While there are no more sections 278 while (section != NULL) { 279 gelf_getshdr(section, &shdr); 280 281 if (shdr.sh_type == SHT_SYMTAB) { 282 found = true; 283 data = elf_getdata(section, NULL); 284 count = shdr.sh_size / shdr.sh_entsize; 285 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); 286 287 // loop through all the symbols, only loading global ones 288 for (ii = 0; ii < count; ++ii) { 289 gelf_getsym(data, ii, &sym); 290 if (GELF_ST_BIND(sym.st_info) == binding) { 291 symtab->insert(sym.st_value, 292 elf_strptr(elf, shdr.sh_link, sym.st_name)); 293 } 294 } 295 } 296 ++sec_idx; 297 section = elf_getscn(elf, sec_idx); 298 } 299 300 elf_end(elf); 301 302 return found; 303} 304 305bool 306ElfObject::loadGlobalSymbols(SymbolTable *symtab) 307{ 308 return loadSomeSymbols(symtab, STB_GLOBAL); 309} 310 311bool 312ElfObject::loadLocalSymbols(SymbolTable *symtab) 313{ 314 return loadSomeSymbols(symtab, STB_LOCAL); 315} 316