elf_object.cc revision 3925
112SN/A/* 21762SN/A * Copyright (c) 2003-2005 The Regents of The University of Michigan 312SN/A * All rights reserved. 412SN/A * 512SN/A * Redistribution and use in source and binary forms, with or without 612SN/A * modification, are permitted provided that the following conditions are 712SN/A * met: redistributions of source code must retain the above copyright 812SN/A * notice, this list of conditions and the following disclaimer; 912SN/A * redistributions in binary form must reproduce the above copyright 1012SN/A * notice, this list of conditions and the following disclaimer in the 1112SN/A * documentation and/or other materials provided with the distribution; 1212SN/A * neither the name of the copyright holders nor the names of its 1312SN/A * contributors may be used to endorse or promote products derived from 1412SN/A * this software without specific prior written permission. 1512SN/A * 1612SN/A * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 1712SN/A * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 1812SN/A * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 1912SN/A * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 2012SN/A * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 2112SN/A * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 2212SN/A * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2312SN/A * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 2412SN/A * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 2512SN/A * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 2612SN/A * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 272665Ssaidi@eecs.umich.edu * 282665Ssaidi@eecs.umich.edu * Authors: Steve Reinhardt 292665Ssaidi@eecs.umich.edu * Ali Saidi 3012SN/A */ 3112SN/A 3212SN/A#include <string> 3312SN/A 34468SN/A// Because of the -Wundef flag we have to do this 35468SN/A#define __LIBELF_INTERNAL__ 0 36468SN/A#define __LIBELF_NEED_LINK_H 0 37661SN/A#define __LIBELF_SYMBOL_VERSIONS 0 38468SN/A 392634Sstever@eecs.umich.edu#include "gelf.h" 40468SN/A 4156SN/A#include "base/loader/elf_object.hh" 422439SN/A#include "base/misc.hh" 4312SN/A 4456SN/A#include "base/loader/symtab.hh" 4512SN/A 4656SN/A#include "base/trace.hh" // for DPRINTF 4712SN/A 482423SN/A#include "sim/byteswap.hh" 492423SN/A 5012SN/A 5112SN/Ausing namespace std; 5212SN/A 5312SN/AObjectFile * 5412SN/AElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data) 5512SN/A{ 56443SN/A Elf *elf; 57443SN/A GElf_Ehdr ehdr; 582207SN/A Arch arch = UnknownArch; 592207SN/A OpSys opSys = UnknownOpSys; 60443SN/A 61468SN/A // check that header matches library version 621708SN/A if (elf_version(EV_CURRENT) == EV_NONE) 631708SN/A panic("wrong elf version number!"); 64443SN/A 65468SN/A // get a pointer to elf structure 66443SN/A elf = elf_memory((char*)data,len); 67468SN/A // will only fail if fd is invalid 68443SN/A assert(elf != NULL); 69443SN/A 70468SN/A // Check that we actually have a elf file 71468SN/A if (gelf_getehdr(elf, &ehdr) ==0) { 72443SN/A DPRINTFR(Loader, "Not ELF\n"); 73443SN/A elf_end(elf); 74443SN/A return NULL; 752476SN/A } else { 762207SN/A //Detect the architecture 772207SN/A //Since we don't know how to check for alpha right now, we'll 782207SN/A //just assume if it wasn't something else and it's 64 bit, that's 792207SN/A //what it must be. 802207SN/A if (ehdr.e_machine == EM_SPARC64 || 812207SN/A ehdr.e_machine == EM_SPARC || 822620SN/A ehdr.e_machine == EM_SPARCV9) { 832207SN/A arch = ObjectFile::SPARC; 842207SN/A } else if (ehdr.e_machine == EM_MIPS 852207SN/A && ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 862472SN/A arch = ObjectFile::Mips; 872207SN/A } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 882207SN/A arch = ObjectFile::Alpha; 892207SN/A } else { 902600SN/A warn("Unknown architecture: %d\n", ehdr.e_machine); 912207SN/A arch = ObjectFile::UnknownArch; 922207SN/A } 932207SN/A 942207SN/A //Detect the operating system 952207SN/A switch (ehdr.e_ident[EI_OSABI]) 962207SN/A { 972238SN/A 982207SN/A case ELFOSABI_LINUX: 992207SN/A opSys = ObjectFile::Linux; 1002207SN/A break; 1012207SN/A case ELFOSABI_SOLARIS: 1022207SN/A opSys = ObjectFile::Solaris; 1032238SN/A break; 1042207SN/A case ELFOSABI_TRU64: 1052207SN/A opSys = ObjectFile::Tru64; 1062238SN/A break; 1072207SN/A default: 1082207SN/A opSys = ObjectFile::UnknownOpSys; 1092207SN/A } 1102207SN/A 1112238SN/A //take a look at the .note.ABI section 1122238SN/A //It can let us know what's what. 1132600SN/A if (opSys == ObjectFile::UnknownOpSys) { 1142238SN/A Elf_Scn *section; 1152238SN/A GElf_Shdr shdr; 1162238SN/A Elf_Data *data; 1172238SN/A uint32_t osAbi;; 1182238SN/A int secIdx = 1; 1192238SN/A 1202238SN/A // Get the first section 1212238SN/A section = elf_getscn(elf, secIdx); 1222238SN/A 1232238SN/A // While there are no more sections 1242600SN/A while (section != NULL && opSys == ObjectFile::UnknownOpSys) { 1252238SN/A gelf_getshdr(section, &shdr); 1262238SN/A if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag", 1272238SN/A elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) { 1282238SN/A // we have found a ABI note section 1292238SN/A // Check the 5th 32bit word for OS 0 == linux, 1 == hurd, 1302238SN/A // 2 == solaris, 3 == freebsd 1312238SN/A data = elf_rawdata(section, NULL); 1322238SN/A assert(data->d_buf); 1332238SN/A if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB) 1342238SN/A osAbi = htole(((uint32_t*)data->d_buf)[4]); 1352238SN/A else 1362238SN/A osAbi = htobe(((uint32_t*)data->d_buf)[4]); 1372238SN/A 1382238SN/A switch(osAbi) { 1392238SN/A case 0: 1402238SN/A opSys = ObjectFile::Linux; 1412238SN/A break; 1422238SN/A case 2: 1432238SN/A opSys = ObjectFile::Solaris; 1442238SN/A break; 1452238SN/A } 1462238SN/A } // if section found 1472600SN/A if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 1482600SN/A opSys = ObjectFile::Solaris; 1492600SN/A if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 1502600SN/A opSys = ObjectFile::Solaris; 1512600SN/A 1522238SN/A section = elf_getscn(elf, ++secIdx); 1532238SN/A } // while sections 1542238SN/A } 1552472SN/A 1562976Sgblack@eecs.umich.edu ElfObject * result = new ElfObject(fname, fd, len, data, arch, opSys); 1572976Sgblack@eecs.umich.edu 1582976Sgblack@eecs.umich.edu //The number of headers in the file 1592976Sgblack@eecs.umich.edu result->_programHeaderCount = ehdr.e_phnum; 1602976Sgblack@eecs.umich.edu //Record the size of each entry 1612976Sgblack@eecs.umich.edu result->_programHeaderSize = ehdr.e_phentsize; 1622976Sgblack@eecs.umich.edu if(result->_programHeaderCount) //If there is a program header table 1632976Sgblack@eecs.umich.edu { 1642976Sgblack@eecs.umich.edu //Figure out the virtual address of the header table in the 1652976Sgblack@eecs.umich.edu //final memory image. We use the program headers themselves 1662976Sgblack@eecs.umich.edu //to translate from a file offset to the address in the image. 1672976Sgblack@eecs.umich.edu GElf_Phdr phdr; 1682976Sgblack@eecs.umich.edu uint64_t e_phoff = ehdr.e_phoff; 1692976Sgblack@eecs.umich.edu result->_programHeaderTable = 0; 1702976Sgblack@eecs.umich.edu for(int hdrnum = 0; hdrnum < result->_programHeaderCount; hdrnum++) 1712976Sgblack@eecs.umich.edu { 1722976Sgblack@eecs.umich.edu gelf_getphdr(elf, hdrnum, &phdr); 1732976Sgblack@eecs.umich.edu //Check if we've found the segment with the headers in it 1742976Sgblack@eecs.umich.edu if(phdr.p_offset <= e_phoff && 1752976Sgblack@eecs.umich.edu phdr.p_offset + phdr.p_filesz > e_phoff) 1762976Sgblack@eecs.umich.edu { 1772976Sgblack@eecs.umich.edu result->_programHeaderTable = phdr.p_vaddr + e_phoff; 1782976Sgblack@eecs.umich.edu break; 1792976Sgblack@eecs.umich.edu } 1802976Sgblack@eecs.umich.edu } 1812976Sgblack@eecs.umich.edu } 1822976Sgblack@eecs.umich.edu else 1832976Sgblack@eecs.umich.edu result->_programHeaderTable = 0; 1842976Sgblack@eecs.umich.edu 1852976Sgblack@eecs.umich.edu 1862238SN/A elf_end(elf); 1872976Sgblack@eecs.umich.edu return result; 18812SN/A } 18912SN/A} 19012SN/A 19112SN/A 19212SN/AElfObject::ElfObject(const string &_filename, int _fd, 193360SN/A size_t _len, uint8_t *_data, 194360SN/A Arch _arch, OpSys _opSys) 195360SN/A : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys) 196443SN/A 19712SN/A{ 198443SN/A Elf *elf; 199443SN/A GElf_Ehdr ehdr; 20012SN/A 201468SN/A // check that header matches library version 2021708SN/A if (elf_version(EV_CURRENT) == EV_NONE) 2031708SN/A panic("wrong elf version number!"); 20412SN/A 205468SN/A // get a pointer to elf structure 206443SN/A elf = elf_memory((char*)fileData,len); 207468SN/A // will only fail if fd is invalid 208443SN/A assert(elf != NULL); 20912SN/A 210468SN/A // Check that we actually have a elf file 211468SN/A if (gelf_getehdr(elf, &ehdr) ==0) { 212443SN/A panic("Not ELF, shouldn't be here"); 21312SN/A } 21412SN/A 215468SN/A entry = ehdr.e_entry; 21612SN/A 2172472SN/A 218468SN/A // initialize segment sizes to 0 in case they're not present 219468SN/A text.size = data.size = bss.size = 0; 220468SN/A 221468SN/A for (int i = 0; i < ehdr.e_phnum; ++i) { 222468SN/A GElf_Phdr phdr; 223468SN/A if (gelf_getphdr(elf, i, &phdr) == 0) { 224468SN/A panic("gelf_getphdr failed for section %d", i); 225468SN/A } 226468SN/A 227468SN/A // for now we don't care about non-loadable segments 228468SN/A if (!(phdr.p_type & PT_LOAD)) 229468SN/A continue; 230468SN/A 231468SN/A // the headers don't explicitly distinguish text from data, 232468SN/A // but empirically the text segment comes first. 233468SN/A if (text.size == 0) { // haven't seen text segment yet 234468SN/A text.baseAddr = phdr.p_vaddr; 235468SN/A text.size = phdr.p_filesz; 2362420SN/A text.fileImage = fileData + phdr.p_offset; 237468SN/A // if there's any padding at the end that's not in the 238468SN/A // file, call it the bss. This happens in the "text" 239468SN/A // segment if there's only one loadable segment (as for 240468SN/A // kernel images). 241468SN/A bss.size = phdr.p_memsz - phdr.p_filesz; 242468SN/A bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; 2432420SN/A bss.fileImage = NULL; 2442476SN/A } else if (data.size == 0) { // have text, this must be data 245468SN/A data.baseAddr = phdr.p_vaddr; 246468SN/A data.size = phdr.p_filesz; 2472420SN/A data.fileImage = fileData + phdr.p_offset; 248468SN/A // if there's any padding at the end that's not in the 249468SN/A // file, call it the bss. Warn if this happens for both 250468SN/A // the text & data segments (should only have one bss). 251468SN/A if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) { 252468SN/A warn("Two implied bss segments in file!\n"); 253468SN/A } 254468SN/A bss.size = phdr.p_memsz - phdr.p_filesz; 255468SN/A bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; 2562420SN/A bss.fileImage = NULL; 2572476SN/A } else { 2582476SN/A warn("More than two loadable segments in ELF object."); 2592476SN/A warn("Ignoring segment @ 0x%x length 0x%x.", 2602476SN/A phdr.p_vaddr, phdr.p_filesz); 261468SN/A } 262468SN/A } 263468SN/A 264468SN/A // should have found at least one loadable segment 265468SN/A assert(text.size != 0); 266468SN/A 267468SN/A DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", 268468SN/A text.baseAddr, text.size, data.baseAddr, data.size, 269468SN/A bss.baseAddr, bss.size); 270468SN/A 271443SN/A elf_end(elf); 272443SN/A 273468SN/A // We will actually read the sections when we need to load them 27412SN/A} 27512SN/A 27612SN/A 27712SN/Abool 278468SN/AElfObject::loadSomeSymbols(SymbolTable *symtab, int binding) 27912SN/A{ 280443SN/A Elf *elf; 281766SN/A int sec_idx = 1; // there is a 0 but it is nothing, go figure 282443SN/A Elf_Scn *section; 283443SN/A GElf_Shdr shdr; 284443SN/A Elf_Data *data; 285443SN/A int count, ii; 286443SN/A bool found = false; 287443SN/A GElf_Sym sym; 288443SN/A 289443SN/A if (!symtab) 290443SN/A return false; 291443SN/A 292468SN/A // check that header matches library version 2931708SN/A if (elf_version(EV_CURRENT) == EV_NONE) 2941708SN/A panic("wrong elf version number!"); 295443SN/A 296468SN/A // get a pointer to elf structure 297443SN/A elf = elf_memory((char*)fileData,len); 298443SN/A 299443SN/A assert(elf != NULL); 300443SN/A 301468SN/A // Get the first section 302454SN/A section = elf_getscn(elf, sec_idx); 303443SN/A 304468SN/A // While there are no more sections 305468SN/A while (section != NULL) { 306443SN/A gelf_getshdr(section, &shdr); 307443SN/A 308468SN/A if (shdr.sh_type == SHT_SYMTAB) { 309443SN/A found = true; 310443SN/A data = elf_getdata(section, NULL); 311443SN/A count = shdr.sh_size / shdr.sh_entsize; 312443SN/A DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); 313443SN/A 314468SN/A // loop through all the symbols, only loading global ones 315468SN/A for (ii = 0; ii < count; ++ii) { 316443SN/A gelf_getsym(data, ii, &sym); 317836SN/A if (GELF_ST_BIND(sym.st_info) == binding) { 318468SN/A symtab->insert(sym.st_value, 319468SN/A elf_strptr(elf, shdr.sh_link, sym.st_name)); 320443SN/A } 321443SN/A } 322443SN/A } 323454SN/A ++sec_idx; 324454SN/A section = elf_getscn(elf, sec_idx); 325443SN/A } 326443SN/A 327443SN/A elf_end(elf); 328443SN/A 329443SN/A return found; 33012SN/A} 33112SN/A 33212SN/Abool 3333812Ssaidi@eecs.umich.eduElfObject::loadGlobalSymbols(SymbolTable *symtab, Addr addrMask) 334468SN/A{ 335468SN/A return loadSomeSymbols(symtab, STB_GLOBAL); 336468SN/A} 337468SN/A 338468SN/Abool 3393812Ssaidi@eecs.umich.eduElfObject::loadLocalSymbols(SymbolTable *symtab, Addr addrMask) 34012SN/A{ 341468SN/A return loadSomeSymbols(symtab, STB_LOCAL); 34212SN/A} 3433917Ssaidi@eecs.umich.edu 3443917Ssaidi@eecs.umich.edubool 3453917Ssaidi@eecs.umich.eduElfObject::isDynamic() 3463917Ssaidi@eecs.umich.edu{ 3473917Ssaidi@eecs.umich.edu Elf *elf; 3483917Ssaidi@eecs.umich.edu int sec_idx = 1; // there is a 0 but it is nothing, go figure 3493917Ssaidi@eecs.umich.edu Elf_Scn *section; 3503917Ssaidi@eecs.umich.edu GElf_Shdr shdr; 3513917Ssaidi@eecs.umich.edu 3523917Ssaidi@eecs.umich.edu GElf_Ehdr ehdr; 3533917Ssaidi@eecs.umich.edu 3543917Ssaidi@eecs.umich.edu // check that header matches library version 3553917Ssaidi@eecs.umich.edu if (elf_version(EV_CURRENT) == EV_NONE) 3563917Ssaidi@eecs.umich.edu panic("wrong elf version number!"); 3573917Ssaidi@eecs.umich.edu 3583917Ssaidi@eecs.umich.edu // get a pointer to elf structure 3593917Ssaidi@eecs.umich.edu elf = elf_memory((char*)fileData,len); 3603917Ssaidi@eecs.umich.edu assert(elf != NULL); 3613917Ssaidi@eecs.umich.edu 3623917Ssaidi@eecs.umich.edu // Check that we actually have a elf file 3633917Ssaidi@eecs.umich.edu if (gelf_getehdr(elf, &ehdr) ==0) { 3643917Ssaidi@eecs.umich.edu panic("Not ELF, shouldn't be here"); 3653917Ssaidi@eecs.umich.edu } 3663917Ssaidi@eecs.umich.edu 3673917Ssaidi@eecs.umich.edu // Get the first section 3683917Ssaidi@eecs.umich.edu section = elf_getscn(elf, sec_idx); 3693917Ssaidi@eecs.umich.edu 3703917Ssaidi@eecs.umich.edu // While there are no more sections 3713917Ssaidi@eecs.umich.edu while (section != NULL) { 3723917Ssaidi@eecs.umich.edu gelf_getshdr(section, &shdr); 3733925Ssaidi@eecs.umich.edu if (!strcmp(".interp", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 3743917Ssaidi@eecs.umich.edu return true; 3753917Ssaidi@eecs.umich.edu section = elf_getscn(elf, ++sec_idx); 3763917Ssaidi@eecs.umich.edu } // while sections 3773917Ssaidi@eecs.umich.edu return false; 3783917Ssaidi@eecs.umich.edu} 3793917Ssaidi@eecs.umich.edu 3803917Ssaidi@eecs.umich.edu 381