elf_object.cc revision 2665
18113Sgblack@eecs.umich.edu/* 28113Sgblack@eecs.umich.edu * Copyright (c) 2003-2005 The Regents of The University of Michigan 38113Sgblack@eecs.umich.edu * All rights reserved. 48113Sgblack@eecs.umich.edu * 58113Sgblack@eecs.umich.edu * Redistribution and use in source and binary forms, with or without 68113Sgblack@eecs.umich.edu * modification, are permitted provided that the following conditions are 78113Sgblack@eecs.umich.edu * met: redistributions of source code must retain the above copyright 88113Sgblack@eecs.umich.edu * notice, this list of conditions and the following disclaimer; 98113Sgblack@eecs.umich.edu * redistributions in binary form must reproduce the above copyright 108113Sgblack@eecs.umich.edu * notice, this list of conditions and the following disclaimer in the 118113Sgblack@eecs.umich.edu * documentation and/or other materials provided with the distribution; 128113Sgblack@eecs.umich.edu * neither the name of the copyright holders nor the names of its 138113Sgblack@eecs.umich.edu * contributors may be used to endorse or promote products derived from 148113Sgblack@eecs.umich.edu * this software without specific prior written permission. 158113Sgblack@eecs.umich.edu * 168113Sgblack@eecs.umich.edu * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 178113Sgblack@eecs.umich.edu * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 188113Sgblack@eecs.umich.edu * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 198113Sgblack@eecs.umich.edu * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 208113Sgblack@eecs.umich.edu * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 218113Sgblack@eecs.umich.edu * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 228113Sgblack@eecs.umich.edu * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 238113Sgblack@eecs.umich.edu * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 248113Sgblack@eecs.umich.edu * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 258113Sgblack@eecs.umich.edu * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 268113Sgblack@eecs.umich.edu * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 278113Sgblack@eecs.umich.edu * 288113Sgblack@eecs.umich.edu * Authors: Steve Reinhardt 298113Sgblack@eecs.umich.edu * Ali Saidi 308113Sgblack@eecs.umich.edu */ 318113Sgblack@eecs.umich.edu 328113Sgblack@eecs.umich.edu#include <string> 338113Sgblack@eecs.umich.edu 348113Sgblack@eecs.umich.edu// Because of the -Wundef flag we have to do this 358113Sgblack@eecs.umich.edu#define __LIBELF_INTERNAL__ 0 368113Sgblack@eecs.umich.edu#define __LIBELF_NEED_LINK_H 0 378113Sgblack@eecs.umich.edu#define __LIBELF_SYMBOL_VERSIONS 0 388113Sgblack@eecs.umich.edu 398113Sgblack@eecs.umich.edu#include "gelf.h" 40 41#include "base/loader/elf_object.hh" 42#include "base/misc.hh" 43 44#include "base/loader/symtab.hh" 45 46#include "base/trace.hh" // for DPRINTF 47 48#include "sim/byteswap.hh" 49 50 51using namespace std; 52 53ObjectFile * 54ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data) 55{ 56 Elf *elf; 57 GElf_Ehdr ehdr; 58 Arch arch = UnknownArch; 59 OpSys opSys = UnknownOpSys; 60 61 // check that header matches library version 62 if (elf_version(EV_CURRENT) == EV_NONE) 63 panic("wrong elf version number!"); 64 65 // get a pointer to elf structure 66 elf = elf_memory((char*)data,len); 67 // will only fail if fd is invalid 68 assert(elf != NULL); 69 70 // Check that we actually have a elf file 71 if (gelf_getehdr(elf, &ehdr) ==0) { 72 DPRINTFR(Loader, "Not ELF\n"); 73 elf_end(elf); 74 return NULL; 75 } else { 76 //Detect the architecture 77 //Since we don't know how to check for alpha right now, we'll 78 //just assume if it wasn't something else and it's 64 bit, that's 79 //what it must be. 80 if (ehdr.e_machine == EM_SPARC64 || 81 ehdr.e_machine == EM_SPARC || 82 ehdr.e_machine == EM_SPARCV9) { 83 arch = ObjectFile::SPARC; 84 } else if (ehdr.e_machine == EM_MIPS 85 && ehdr.e_ident[EI_CLASS] == ELFCLASS32) { 86 arch = ObjectFile::Mips; 87 } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) { 88 arch = ObjectFile::Alpha; 89 } else { 90 warn("Unknown architecture: %d\n", ehdr.e_machine); 91 arch = ObjectFile::UnknownArch; 92 } 93 94 //Detect the operating system 95 switch (ehdr.e_ident[EI_OSABI]) 96 { 97 98 case ELFOSABI_LINUX: 99 opSys = ObjectFile::Linux; 100 break; 101 case ELFOSABI_SOLARIS: 102 opSys = ObjectFile::Solaris; 103 break; 104 case ELFOSABI_TRU64: 105 opSys = ObjectFile::Tru64; 106 break; 107 default: 108 opSys = ObjectFile::UnknownOpSys; 109 } 110 111 //take a look at the .note.ABI section 112 //It can let us know what's what. 113 if (opSys == ObjectFile::UnknownOpSys) { 114 Elf_Scn *section; 115 GElf_Shdr shdr; 116 Elf_Data *data; 117 uint32_t osAbi;; 118 int secIdx = 1; 119 120 // Get the first section 121 section = elf_getscn(elf, secIdx); 122 123 // While there are no more sections 124 while (section != NULL && opSys == ObjectFile::UnknownOpSys) { 125 gelf_getshdr(section, &shdr); 126 if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag", 127 elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) { 128 // we have found a ABI note section 129 // Check the 5th 32bit word for OS 0 == linux, 1 == hurd, 130 // 2 == solaris, 3 == freebsd 131 data = elf_rawdata(section, NULL); 132 assert(data->d_buf); 133 if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB) 134 osAbi = htole(((uint32_t*)data->d_buf)[4]); 135 else 136 osAbi = htobe(((uint32_t*)data->d_buf)[4]); 137 138 switch(osAbi) { 139 case 0: 140 opSys = ObjectFile::Linux; 141 break; 142 case 2: 143 opSys = ObjectFile::Solaris; 144 break; 145 } 146 } // if section found 147 if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 148 opSys = ObjectFile::Solaris; 149 if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) 150 opSys = ObjectFile::Solaris; 151 152 section = elf_getscn(elf, ++secIdx); 153 } // while sections 154 } 155 156 elf_end(elf); 157 return new ElfObject(fname, fd, len, data, arch, opSys); 158 } 159} 160 161 162ElfObject::ElfObject(const string &_filename, int _fd, 163 size_t _len, uint8_t *_data, 164 Arch _arch, OpSys _opSys) 165 : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys) 166 167{ 168 Elf *elf; 169 GElf_Ehdr ehdr; 170 171 // check that header matches library version 172 if (elf_version(EV_CURRENT) == EV_NONE) 173 panic("wrong elf version number!"); 174 175 // get a pointer to elf structure 176 elf = elf_memory((char*)fileData,len); 177 // will only fail if fd is invalid 178 assert(elf != NULL); 179 180 // Check that we actually have a elf file 181 if (gelf_getehdr(elf, &ehdr) ==0) { 182 panic("Not ELF, shouldn't be here"); 183 } 184 185 entry = ehdr.e_entry; 186 187 188 // initialize segment sizes to 0 in case they're not present 189 text.size = data.size = bss.size = 0; 190 191 for (int i = 0; i < ehdr.e_phnum; ++i) { 192 GElf_Phdr phdr; 193 if (gelf_getphdr(elf, i, &phdr) == 0) { 194 panic("gelf_getphdr failed for section %d", i); 195 } 196 197 // for now we don't care about non-loadable segments 198 if (!(phdr.p_type & PT_LOAD)) 199 continue; 200 201 // the headers don't explicitly distinguish text from data, 202 // but empirically the text segment comes first. 203 if (text.size == 0) { // haven't seen text segment yet 204 text.baseAddr = phdr.p_vaddr; 205 text.size = phdr.p_filesz; 206 text.fileImage = fileData + phdr.p_offset; 207 // if there's any padding at the end that's not in the 208 // file, call it the bss. This happens in the "text" 209 // segment if there's only one loadable segment (as for 210 // kernel images). 211 bss.size = phdr.p_memsz - phdr.p_filesz; 212 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; 213 bss.fileImage = NULL; 214 } else if (data.size == 0) { // have text, this must be data 215 data.baseAddr = phdr.p_vaddr; 216 data.size = phdr.p_filesz; 217 data.fileImage = fileData + phdr.p_offset; 218 // if there's any padding at the end that's not in the 219 // file, call it the bss. Warn if this happens for both 220 // the text & data segments (should only have one bss). 221 if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) { 222 warn("Two implied bss segments in file!\n"); 223 } 224 bss.size = phdr.p_memsz - phdr.p_filesz; 225 bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; 226 bss.fileImage = NULL; 227 } else { 228 warn("More than two loadable segments in ELF object."); 229 warn("Ignoring segment @ 0x%x length 0x%x.", 230 phdr.p_vaddr, phdr.p_filesz); 231 } 232 } 233 234 // should have found at least one loadable segment 235 assert(text.size != 0); 236 237 DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", 238 text.baseAddr, text.size, data.baseAddr, data.size, 239 bss.baseAddr, bss.size); 240 241 elf_end(elf); 242 243 // We will actually read the sections when we need to load them 244} 245 246 247bool 248ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding) 249{ 250 Elf *elf; 251 int sec_idx = 1; // there is a 0 but it is nothing, go figure 252 Elf_Scn *section; 253 GElf_Shdr shdr; 254 Elf_Data *data; 255 int count, ii; 256 bool found = false; 257 GElf_Sym sym; 258 259 if (!symtab) 260 return false; 261 262 // check that header matches library version 263 if (elf_version(EV_CURRENT) == EV_NONE) 264 panic("wrong elf version number!"); 265 266 // get a pointer to elf structure 267 elf = elf_memory((char*)fileData,len); 268 269 assert(elf != NULL); 270 271 // Get the first section 272 section = elf_getscn(elf, sec_idx); 273 274 // While there are no more sections 275 while (section != NULL) { 276 gelf_getshdr(section, &shdr); 277 278 if (shdr.sh_type == SHT_SYMTAB) { 279 found = true; 280 data = elf_getdata(section, NULL); 281 count = shdr.sh_size / shdr.sh_entsize; 282 DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); 283 284 // loop through all the symbols, only loading global ones 285 for (ii = 0; ii < count; ++ii) { 286 gelf_getsym(data, ii, &sym); 287 if (GELF_ST_BIND(sym.st_info) == binding) { 288 symtab->insert(sym.st_value, 289 elf_strptr(elf, shdr.sh_link, sym.st_name)); 290 } 291 } 292 } 293 ++sec_idx; 294 section = elf_getscn(elf, sec_idx); 295 } 296 297 elf_end(elf); 298 299 return found; 300} 301 302bool 303ElfObject::loadGlobalSymbols(SymbolTable *symtab) 304{ 305 return loadSomeSymbols(symtab, STB_GLOBAL); 306} 307 308bool 309ElfObject::loadLocalSymbols(SymbolTable *symtab) 310{ 311 return loadSomeSymbols(symtab, STB_LOCAL); 312} 313