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Diffstat (limited to 'src/base/loader/elf_object.cc')
| -rw-r--r-- | src/base/loader/elf_object.cc | 315 |
1 files changed, 315 insertions, 0 deletions
diff --git a/src/base/loader/elf_object.cc b/src/base/loader/elf_object.cc new file mode 100644 index 000000000..165501e1c --- /dev/null +++ b/src/base/loader/elf_object.cc @@ -0,0 +1,315 @@ +/* + * Copyright (c) 2003-2005 The Regents of The University of Michigan + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer; + * redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution; + * neither the name of the copyright holders nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include <string> + +// Because of the -Wundef flag we have to do this +#define __LIBELF_INTERNAL__ 0 +// counterintuitive, but the flag below causes libelf to define +// 64-bit elf types that apparently didn't exist in some older +// versions of Linux. They seem to be there in 2.4.x, so don't +// set this now (it causes things to break on 64-bit platforms). +#define __LIBELF64_LINUX 0 +#define __LIBELF_NEED_LINK_H 0 +#define __LIBELF_SYMBOL_VERSIONS 0 + +#include "libelf/libelf.h" +#include "libelf/gelf.h" + +#include "base/loader/elf_object.hh" +#include "base/misc.hh" + +#include "base/loader/symtab.hh" + +#include "base/trace.hh" // for DPRINTF + +#include "sim/byteswap.hh" + + +using namespace std; + +ObjectFile * +ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data) +{ + Elf *elf; + GElf_Ehdr ehdr; + Arch arch = UnknownArch; + OpSys opSys = UnknownOpSys; + + // check that header matches library version + if (elf_version(EV_CURRENT) == EV_NONE) + panic("wrong elf version number!"); + + // get a pointer to elf structure + elf = elf_memory((char*)data,len); + // will only fail if fd is invalid + assert(elf != NULL); + + // Check that we actually have a elf file + if (gelf_getehdr(elf, &ehdr) ==0) { + DPRINTFR(Loader, "Not ELF\n"); + elf_end(elf); + return NULL; + } else { + //Detect the architecture + //Since we don't know how to check for alpha right now, we'll + //just assume if it wasn't something else and it's 64 bit, that's + //what it must be. + if (ehdr.e_machine == EM_SPARC64 || + ehdr.e_machine == EM_SPARC || + ehdr.e_machine == EM_SPARCV9) { + arch = ObjectFile::SPARC; + } else if (ehdr.e_machine == EM_MIPS + && ehdr.e_ident[EI_CLASS] == ELFCLASS32) { + arch = ObjectFile::Mips; + } else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) { + arch = ObjectFile::Alpha; + } else { + warn("Unknown architecture: %d\n", ehdr.e_machine); + arch = ObjectFile::UnknownArch; + } + + //Detect the operating system + switch (ehdr.e_ident[EI_OSABI]) + { + + case ELFOSABI_LINUX: + opSys = ObjectFile::Linux; + break; + case ELFOSABI_SOLARIS: + opSys = ObjectFile::Solaris; + break; + case ELFOSABI_TRU64: + opSys = ObjectFile::Tru64; + break; + default: + opSys = ObjectFile::UnknownOpSys; + } + + //take a look at the .note.ABI section + //It can let us know what's what. + if (opSys == ObjectFile::UnknownOpSys) { + Elf_Scn *section; + GElf_Shdr shdr; + Elf_Data *data; + uint32_t osAbi;; + int secIdx = 1; + + // Get the first section + section = elf_getscn(elf, secIdx); + + // While there are no more sections + while (section != NULL && opSys == ObjectFile::UnknownOpSys) { + gelf_getshdr(section, &shdr); + if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag", + elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) { + // we have found a ABI note section + // Check the 5th 32bit word for OS 0 == linux, 1 == hurd, + // 2 == solaris, 3 == freebsd + data = elf_rawdata(section, NULL); + assert(data->d_buf); + if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB) + osAbi = htole(((uint32_t*)data->d_buf)[4]); + else + osAbi = htobe(((uint32_t*)data->d_buf)[4]); + + switch(osAbi) { + case 0: + opSys = ObjectFile::Linux; + break; + case 2: + opSys = ObjectFile::Solaris; + break; + } + } // if section found + if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) + opSys = ObjectFile::Solaris; + if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) + opSys = ObjectFile::Solaris; + + section = elf_getscn(elf, ++secIdx); + } // while sections + } + + elf_end(elf); + return new ElfObject(fname, fd, len, data, arch, opSys); + } +} + + +ElfObject::ElfObject(const string &_filename, int _fd, + size_t _len, uint8_t *_data, + Arch _arch, OpSys _opSys) + : ObjectFile(_filename, _fd, _len, _data, _arch, _opSys) + +{ + Elf *elf; + GElf_Ehdr ehdr; + + // check that header matches library version + if (elf_version(EV_CURRENT) == EV_NONE) + panic("wrong elf version number!"); + + // get a pointer to elf structure + elf = elf_memory((char*)fileData,len); + // will only fail if fd is invalid + assert(elf != NULL); + + // Check that we actually have a elf file + if (gelf_getehdr(elf, &ehdr) ==0) { + panic("Not ELF, shouldn't be here"); + } + + entry = ehdr.e_entry; + + + // initialize segment sizes to 0 in case they're not present + text.size = data.size = bss.size = 0; + + for (int i = 0; i < ehdr.e_phnum; ++i) { + GElf_Phdr phdr; + if (gelf_getphdr(elf, i, &phdr) == 0) { + panic("gelf_getphdr failed for section %d", i); + } + + // for now we don't care about non-loadable segments + if (!(phdr.p_type & PT_LOAD)) + continue; + + // the headers don't explicitly distinguish text from data, + // but empirically the text segment comes first. + if (text.size == 0) { // haven't seen text segment yet + text.baseAddr = phdr.p_vaddr; + text.size = phdr.p_filesz; + text.fileImage = fileData + phdr.p_offset; + // if there's any padding at the end that's not in the + // file, call it the bss. This happens in the "text" + // segment if there's only one loadable segment (as for + // kernel images). + bss.size = phdr.p_memsz - phdr.p_filesz; + bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; + bss.fileImage = NULL; + } else if (data.size == 0) { // have text, this must be data + data.baseAddr = phdr.p_vaddr; + data.size = phdr.p_filesz; + data.fileImage = fileData + phdr.p_offset; + // if there's any padding at the end that's not in the + // file, call it the bss. Warn if this happens for both + // the text & data segments (should only have one bss). + if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) { + warn("Two implied bss segments in file!\n"); + } + bss.size = phdr.p_memsz - phdr.p_filesz; + bss.baseAddr = phdr.p_vaddr + phdr.p_filesz; + bss.fileImage = NULL; + } else { + warn("More than two loadable segments in ELF object."); + warn("Ignoring segment @ 0x%x length 0x%x.", + phdr.p_vaddr, phdr.p_filesz); + } + } + + // should have found at least one loadable segment + assert(text.size != 0); + + DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n", + text.baseAddr, text.size, data.baseAddr, data.size, + bss.baseAddr, bss.size); + + elf_end(elf); + + // We will actually read the sections when we need to load them +} + + +bool +ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding) +{ + Elf *elf; + int sec_idx = 1; // there is a 0 but it is nothing, go figure + Elf_Scn *section; + GElf_Shdr shdr; + Elf_Data *data; + int count, ii; + bool found = false; + GElf_Sym sym; + + if (!symtab) + return false; + + // check that header matches library version + if (elf_version(EV_CURRENT) == EV_NONE) + panic("wrong elf version number!"); + + // get a pointer to elf structure + elf = elf_memory((char*)fileData,len); + + assert(elf != NULL); + + // Get the first section + section = elf_getscn(elf, sec_idx); + + // While there are no more sections + while (section != NULL) { + gelf_getshdr(section, &shdr); + + if (shdr.sh_type == SHT_SYMTAB) { + found = true; + data = elf_getdata(section, NULL); + count = shdr.sh_size / shdr.sh_entsize; + DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count); + + // loop through all the symbols, only loading global ones + for (ii = 0; ii < count; ++ii) { + gelf_getsym(data, ii, &sym); + if (GELF_ST_BIND(sym.st_info) == binding) { + symtab->insert(sym.st_value, + elf_strptr(elf, shdr.sh_link, sym.st_name)); + } + } + } + ++sec_idx; + section = elf_getscn(elf, sec_idx); + } + + elf_end(elf); + + return found; +} + +bool +ElfObject::loadGlobalSymbols(SymbolTable *symtab) +{ + return loadSomeSymbols(symtab, STB_GLOBAL); +} + +bool +ElfObject::loadLocalSymbols(SymbolTable *symtab) +{ + return loadSomeSymbols(symtab, STB_LOCAL); +} |