a7c95f702c
SConstruct:
Clean up libelf handling. Required better handling of
per-build-root stuff in general (though libelf is the
only thing in that category currently).
src/SConscript:
No libelf-specific stuff in here anymore.
src/base/loader/elf_object.cc:
Just need to include gelf.h... it includes libelf.h.
--HG--
extra : convert_revision : 3d6bdcf8233bda0ac8d08ff777de323df8aa45ae
310 lines
10 KiB
C++
310 lines
10 KiB
C++
/*
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* Copyright (c) 2003-2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <string>
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// Because of the -Wundef flag we have to do this
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#define __LIBELF_INTERNAL__ 0
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#define __LIBELF_NEED_LINK_H 0
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#define __LIBELF_SYMBOL_VERSIONS 0
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#include "gelf.h"
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#include "base/loader/elf_object.hh"
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#include "base/misc.hh"
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#include "base/loader/symtab.hh"
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#include "base/trace.hh" // for DPRINTF
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#include "sim/byteswap.hh"
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using namespace std;
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ObjectFile *
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ElfObject::tryFile(const string &fname, int fd, size_t len, uint8_t *data)
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{
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Elf *elf;
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GElf_Ehdr ehdr;
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Arch arch = UnknownArch;
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OpSys opSys = UnknownOpSys;
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// check that header matches library version
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if (elf_version(EV_CURRENT) == EV_NONE)
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panic("wrong elf version number!");
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// get a pointer to elf structure
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elf = elf_memory((char*)data,len);
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// will only fail if fd is invalid
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assert(elf != NULL);
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// Check that we actually have a elf file
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if (gelf_getehdr(elf, &ehdr) ==0) {
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DPRINTFR(Loader, "Not ELF\n");
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elf_end(elf);
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return NULL;
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} else {
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//Detect the architecture
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//Since we don't know how to check for alpha right now, we'll
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//just assume if it wasn't something else and it's 64 bit, that's
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//what it must be.
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if (ehdr.e_machine == EM_SPARC64 ||
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ehdr.e_machine == EM_SPARC ||
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ehdr.e_machine == EM_SPARCV9) {
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arch = ObjectFile::SPARC;
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} else if (ehdr.e_machine == EM_MIPS
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&& ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
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arch = ObjectFile::Mips;
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} else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
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arch = ObjectFile::Alpha;
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} else {
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warn("Unknown architecture: %d\n", ehdr.e_machine);
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arch = ObjectFile::UnknownArch;
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}
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//Detect the operating system
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switch (ehdr.e_ident[EI_OSABI])
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{
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case ELFOSABI_LINUX:
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opSys = ObjectFile::Linux;
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break;
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case ELFOSABI_SOLARIS:
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opSys = ObjectFile::Solaris;
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break;
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case ELFOSABI_TRU64:
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opSys = ObjectFile::Tru64;
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break;
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default:
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opSys = ObjectFile::UnknownOpSys;
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}
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//take a look at the .note.ABI section
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//It can let us know what's what.
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if (opSys == ObjectFile::UnknownOpSys) {
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Elf_Scn *section;
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GElf_Shdr shdr;
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Elf_Data *data;
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uint32_t osAbi;;
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int secIdx = 1;
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// Get the first section
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section = elf_getscn(elf, secIdx);
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// While there are no more sections
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while (section != NULL && opSys == ObjectFile::UnknownOpSys) {
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gelf_getshdr(section, &shdr);
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if (shdr.sh_type == SHT_NOTE && !strcmp(".note.ABI-tag",
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elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) {
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// we have found a ABI note section
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// Check the 5th 32bit word for OS 0 == linux, 1 == hurd,
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// 2 == solaris, 3 == freebsd
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data = elf_rawdata(section, NULL);
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assert(data->d_buf);
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if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
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osAbi = htole(((uint32_t*)data->d_buf)[4]);
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else
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osAbi = htobe(((uint32_t*)data->d_buf)[4]);
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switch(osAbi) {
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case 0:
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opSys = ObjectFile::Linux;
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break;
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case 2:
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opSys = ObjectFile::Solaris;
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break;
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}
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} // if section found
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if (!strcmp(".SUNW_version", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)))
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opSys = ObjectFile::Solaris;
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if (!strcmp(".stab.index", elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name)))
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opSys = ObjectFile::Solaris;
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section = elf_getscn(elf, ++secIdx);
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} // while sections
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}
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elf_end(elf);
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return new ElfObject(fname, fd, len, data, arch, opSys);
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}
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}
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ElfObject::ElfObject(const string &_filename, int _fd,
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size_t _len, uint8_t *_data,
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Arch _arch, OpSys _opSys)
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: ObjectFile(_filename, _fd, _len, _data, _arch, _opSys)
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{
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Elf *elf;
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GElf_Ehdr ehdr;
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// check that header matches library version
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if (elf_version(EV_CURRENT) == EV_NONE)
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panic("wrong elf version number!");
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// get a pointer to elf structure
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elf = elf_memory((char*)fileData,len);
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// will only fail if fd is invalid
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assert(elf != NULL);
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// Check that we actually have a elf file
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if (gelf_getehdr(elf, &ehdr) ==0) {
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panic("Not ELF, shouldn't be here");
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}
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entry = ehdr.e_entry;
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// initialize segment sizes to 0 in case they're not present
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text.size = data.size = bss.size = 0;
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for (int i = 0; i < ehdr.e_phnum; ++i) {
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GElf_Phdr phdr;
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if (gelf_getphdr(elf, i, &phdr) == 0) {
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panic("gelf_getphdr failed for section %d", i);
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}
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// for now we don't care about non-loadable segments
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if (!(phdr.p_type & PT_LOAD))
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continue;
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// the headers don't explicitly distinguish text from data,
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// but empirically the text segment comes first.
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if (text.size == 0) { // haven't seen text segment yet
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text.baseAddr = phdr.p_vaddr;
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text.size = phdr.p_filesz;
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text.fileImage = fileData + phdr.p_offset;
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// if there's any padding at the end that's not in the
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// file, call it the bss. This happens in the "text"
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// segment if there's only one loadable segment (as for
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// kernel images).
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bss.size = phdr.p_memsz - phdr.p_filesz;
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bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
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bss.fileImage = NULL;
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} else if (data.size == 0) { // have text, this must be data
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data.baseAddr = phdr.p_vaddr;
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data.size = phdr.p_filesz;
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data.fileImage = fileData + phdr.p_offset;
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// if there's any padding at the end that's not in the
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// file, call it the bss. Warn if this happens for both
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// the text & data segments (should only have one bss).
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if (phdr.p_memsz - phdr.p_filesz > 0 && bss.size != 0) {
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warn("Two implied bss segments in file!\n");
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}
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bss.size = phdr.p_memsz - phdr.p_filesz;
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bss.baseAddr = phdr.p_vaddr + phdr.p_filesz;
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bss.fileImage = NULL;
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} else {
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warn("More than two loadable segments in ELF object.");
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warn("Ignoring segment @ 0x%x length 0x%x.",
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phdr.p_vaddr, phdr.p_filesz);
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}
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}
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// should have found at least one loadable segment
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assert(text.size != 0);
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DPRINTFR(Loader, "text: 0x%x %d\ndata: 0x%x %d\nbss: 0x%x %d\n",
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text.baseAddr, text.size, data.baseAddr, data.size,
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bss.baseAddr, bss.size);
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elf_end(elf);
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// We will actually read the sections when we need to load them
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}
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bool
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ElfObject::loadSomeSymbols(SymbolTable *symtab, int binding)
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{
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Elf *elf;
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int sec_idx = 1; // there is a 0 but it is nothing, go figure
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Elf_Scn *section;
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GElf_Shdr shdr;
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Elf_Data *data;
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int count, ii;
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bool found = false;
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GElf_Sym sym;
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if (!symtab)
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return false;
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// check that header matches library version
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if (elf_version(EV_CURRENT) == EV_NONE)
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panic("wrong elf version number!");
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// get a pointer to elf structure
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elf = elf_memory((char*)fileData,len);
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assert(elf != NULL);
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// Get the first section
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section = elf_getscn(elf, sec_idx);
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// While there are no more sections
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while (section != NULL) {
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gelf_getshdr(section, &shdr);
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if (shdr.sh_type == SHT_SYMTAB) {
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found = true;
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data = elf_getdata(section, NULL);
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count = shdr.sh_size / shdr.sh_entsize;
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DPRINTF(Loader, "Found Symbol Table, %d symbols present\n", count);
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// loop through all the symbols, only loading global ones
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for (ii = 0; ii < count; ++ii) {
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gelf_getsym(data, ii, &sym);
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if (GELF_ST_BIND(sym.st_info) == binding) {
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symtab->insert(sym.st_value,
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elf_strptr(elf, shdr.sh_link, sym.st_name));
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}
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}
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}
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++sec_idx;
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section = elf_getscn(elf, sec_idx);
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}
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elf_end(elf);
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return found;
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}
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bool
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ElfObject::loadGlobalSymbols(SymbolTable *symtab)
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{
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return loadSomeSymbols(symtab, STB_GLOBAL);
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}
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bool
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ElfObject::loadLocalSymbols(SymbolTable *symtab)
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{
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return loadSomeSymbols(symtab, STB_LOCAL);
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}
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