/*
* 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
//Versioning issues in libelf need to be resolved to get the correct
//SPARC constants.
//If MIPS supports 32 bit executables, this may need to be changed.
//Also, there are other MIPS constants which may be used, like
//EM_MIPS_RS3_LE and EM_MIPS_X
//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 {
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) {
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
section = elf_getscn(elf, ++secIdx);
} // while sections
}
int32_t global_ptr;
if (arch == ObjectFile::Mips) {
Elf_Scn *section;
GElf_Shdr shdr;
Elf_Data *rdata;
int secIdx = 1;
// Get the first section
section = elf_getscn(elf, secIdx);
// While there are no more sections
while (section != NULL) {
gelf_getshdr(section, &shdr);
/*shdr.sh_type == SHT_MIPS_REGINFO && */
if (!strcmp(".reginfo",elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name))) {
// We have found MIPS reginfo section:
// -------------------------------
// Check the 6th 32bit word for the initialized global pointer value
// -------------------------------
rdata = elf_rawdata(section, NULL);
assert(rdata->d_buf);
if(ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
global_ptr = htole(((int32_t*)rdata->d_buf)[5]);
else
global_ptr = htobe(((int32_t*)rdata->d_buf)[5]);
break;
}
section = elf_getscn(elf, ++secIdx);
} // if section found
}
elf_end(elf);
return new ElfObject(fname, fd, len, data, global_ptr,arch, opSys);
}
}
ElfObject::ElfObject(const string &_filename, int _fd,
size_t _len, uint8_t *_data,Addr global_ptr,
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;
globalPtr = global_ptr;
// 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;
}
}
// 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);
}