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/*
* Copyright (c) 2011-2013 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* 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.
*
* Authors: Steve Reinhardt
* Ali Saidi
*/
#include "base/loader/elf_object.hh"
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <cassert>
#include <string>
#include "base/bitfield.hh"
#include "base/loader/symtab.hh"
#include "base/logging.hh"
#include "base/trace.hh"
#include "debug/Loader.hh"
#include "gelf.h"
#include "sim/byteswap.hh"
ObjectFile *
ElfObject::tryFile(const std::string &fname, size_t len, uint8_t *data,
bool skip_interp_check)
{
// check that header matches library version
if (elf_version(EV_CURRENT) == EV_NONE)
panic("wrong elf version number!");
// get a pointer to elf structure
// Check that we actually have a elf file
Elf *elf = elf_memory((char*)data, len);
assert(elf);
GElf_Ehdr ehdr;
if (gelf_getehdr(elf, &ehdr) == 0) {
DPRINTFR(Loader, "Not ELF\n");
elf_end(elf);
return NULL;
}
// Detect the architecture
Arch arch = UnknownArch;
if (ehdr.e_machine == EM_SPARC64 ||
(ehdr.e_machine == EM_SPARC &&
ehdr.e_ident[EI_CLASS] == ELFCLASS64) ||
ehdr.e_machine == EM_SPARCV9) {
arch = SPARC64;
} else if (ehdr.e_machine == EM_SPARC32PLUS ||
(ehdr.e_machine == EM_SPARC &&
ehdr.e_ident[EI_CLASS] == ELFCLASS32)) {
arch = SPARC32;
} else if (ehdr.e_machine == EM_MIPS &&
ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
arch = Mips;
if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
fatal("The binary you're trying to load is compiled for big "
"endian MIPS. gem5\nonly supports little endian MIPS. "
"Please recompile your binary.\n");
}
} else if (ehdr.e_machine == EM_X86_64 &&
ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
arch = X86_64;
} else if (ehdr.e_machine == EM_386 &&
ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
arch = I386;
} else if (ehdr.e_machine == EM_ARM &&
ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
arch = bits(ehdr.e_entry, 0) ? Thumb : Arm;
} else if (ehdr.e_machine == EM_AARCH64 &&
ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
arch = Arm64;
} else if (ehdr.e_machine == EM_RISCV) {
arch = Riscv;
} else if (ehdr.e_machine == EM_PPC &&
ehdr.e_ident[EI_CLASS] == ELFCLASS32) {
arch = Power;
if (ehdr.e_ident[EI_DATA] != ELFDATA2MSB) {
fatal("The binary you're trying to load is compiled for "
"little endian Power.\ngem5 only supports big "
"endian Power. Please recompile your binary.\n");
}
} else if (ehdr.e_machine == EM_PPC64) {
fatal("The binary you're trying to load is compiled for 64-bit "
"Power. M5\n only supports 32-bit Power. Please "
"recompile your binary.\n");
} else if (ehdr.e_ident[EI_CLASS] == ELFCLASS64) {
// 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.
arch = Alpha;
} else {
warn("Unknown architecture: %d\n", ehdr.e_machine);
arch = UnknownArch;
}
// Detect the operating system
OpSys op_sys;
switch (ehdr.e_ident[EI_OSABI]) {
case ELFOSABI_LINUX:
op_sys = Linux;
break;
case ELFOSABI_SOLARIS:
op_sys = Solaris;
break;
case ELFOSABI_TRU64:
op_sys = Tru64;
break;
case ELFOSABI_ARM:
op_sys = LinuxArmOABI;
break;
case ELFOSABI_FREEBSD:
op_sys = FreeBSD;
break;
default:
op_sys = UnknownOpSys;
}
// Take a look at the .note.ABI section.
// It can let us know what's what.
if (op_sys == UnknownOpSys) {
int sec_idx = 1;
// Get the first section
Elf_Scn *section = elf_getscn(elf, sec_idx);
// While there are no more sections
while (section && op_sys == UnknownOpSys) {
GElf_Shdr shdr;
gelf_getshdr(section, &shdr);
char *e_str = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name);
if (shdr.sh_type == SHT_NOTE &&
!strcmp(".note.ABI-tag", e_str)) {
// we have found a ABI note section
// Check the 5th 32bit word for OS 0 == linux, 1 == hurd,
// 2 == solaris, 3 == freebsd
Elf_Data *raw_data = elf_rawdata(section, NULL);
assert(raw_data && raw_data->d_buf);
uint32_t raw_abi = ((uint32_t*)raw_data->d_buf)[4];
bool is_le = ehdr.e_ident[EI_DATA] == ELFDATA2LSB;
uint32_t os_abi = is_le ? htole(raw_abi) : htobe(raw_abi);
switch (os_abi) {
case 0:
op_sys = Linux;
break;
case 1:
fatal("gem5 does not support the HURD ABI.\n");
case 2:
op_sys = Solaris;
break;
case 3:
op_sys = FreeBSD;
break;
}
} // if section found
if (!strcmp(".SUNW_version", e_str) ||
!strcmp(".stab.index", e_str))
op_sys = Solaris;
section = elf_getscn(elf, ++sec_idx);
} // while sections
}
ElfObject * result = new ElfObject(fname, len, data, arch, op_sys);
// The number of headers in the file
result->_programHeaderCount = ehdr.e_phnum;
// Record the size of each entry
result->_programHeaderSize = ehdr.e_phentsize;
result->_programHeaderTable = 0;
if (result->_programHeaderCount) { // If there is a program header table
// Figure out the virtual address of the header table in the
// final memory image. We use the program headers themselves
// to translate from a file offset to the address in the image.
GElf_Phdr phdr;
uint64_t e_phoff = ehdr.e_phoff;
for (int i = 0; i < result->_programHeaderCount; i++) {
gelf_getphdr(elf, i, &phdr);
// Check if we've found the segment with the headers in it
if (phdr.p_offset <= e_phoff &&
phdr.p_offset + phdr.p_filesz > e_phoff) {
result->_programHeaderTable =
phdr.p_paddr + (e_phoff - phdr.p_offset);
break;
}
}
}
if (!skip_interp_check) {
for (int i = 0; i < ehdr.e_phnum; i++) {
GElf_Phdr phdr;
M5_VAR_USED void *check_p = gelf_getphdr(elf, i, &phdr);
assert(check_p != nullptr);
if (phdr.p_type != PT_INTERP)
continue;
char *interp_path = (char*)data + phdr.p_offset;
int fd = open(interp_path, O_RDONLY);
if (fd == -1)
fatal("Unable to open dynamic executable's interpreter.\n");
struct stat sb;
M5_VAR_USED int check_i = fstat(fd, &sb);
assert(check_i == 0);
void *mm = mmap(nullptr, sb.st_size, PROT_READ,
MAP_PRIVATE, fd, 0);
assert(mm != MAP_FAILED);
close(fd);
uint8_t *interp_image = (uint8_t*)mm;
ObjectFile *obj = tryFile(interp_path, sb.st_size,
interp_image, true);
assert(obj != nullptr);
result->interpreter = dynamic_cast<ElfObject*>(obj);
assert(result->interpreter != nullptr);
break;
}
}
elf_end(elf);
return result;
}
ElfObject::ElfObject(const std::string &_filename, size_t _len,
uint8_t *_data, Arch _arch, OpSys _op_sys)
: ObjectFile(_filename, _len, _data, _arch, _op_sys),
_programHeaderTable(0), _programHeaderSize(0), _programHeaderCount(0),
interpreter(nullptr), ldBias(0), relocate(true),
ldMin(std::numeric_limits<Addr>::max()),
ldMax(std::numeric_limits<Addr>::min())
{
// 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 = elf_memory((char*)fileData,len);
assert(elf);
// Check that we actually have a elf file
GElf_Ehdr ehdr;
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;
text.baseAddr = data.baseAddr = bss.baseAddr = 0;
int sec_idx = 1;
// The first address of some important sections.
Addr text_sec_start = 0;
Addr data_sec_start = 0;
Addr bss_sec_start = 0;
// Get the first section
Elf_Scn *section = elf_getscn(elf, sec_idx);
// Find the beginning of the most interesting sections.
while (section) {
GElf_Shdr shdr;
gelf_getshdr(section, &shdr);
char *sec_name = elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name);
if (sec_name) {
if (!strcmp(".text", sec_name)) {
text_sec_start = shdr.sh_addr;
} else if (!strcmp(".data", sec_name)) {
data_sec_start = shdr.sh_addr;
} else if (!strcmp(".bss", sec_name)) {
bss_sec_start = shdr.sh_addr;
}
} else {
Elf_Error errorNum = (Elf_Error)elf_errno();
if (errorNum != ELF_E_NONE) {
const char *errorMessage = elf_errmsg(errorNum);
fatal("Error from libelf: %s.\n", errorMessage);
}
}
section = elf_getscn(elf, ++sec_idx);
}
// Go through all the segments in the program, record them, and scrape
// out information about the text, data, and bss areas needed by other
// code.
for (int i = 0; i < ehdr.e_phnum; ++i) {
GElf_Phdr phdr;
if (gelf_getphdr(elf, i, &phdr) == 0) {
panic("gelf_getphdr failed for segment %d.", i);
}
// for now we don't care about non-loadable segments
if (!(phdr.p_type & PT_LOAD))
continue;
ldMin = std::min(ldMin, phdr.p_vaddr);
ldMax = std::max(ldMax, phdr.p_vaddr + phdr.p_memsz);
// Check to see if this segment contains the bss section.
if (phdr.p_paddr <= bss_sec_start &&
phdr.p_paddr + phdr.p_memsz > bss_sec_start &&
phdr.p_memsz - phdr.p_filesz > 0) {
bss.baseAddr = phdr.p_paddr + phdr.p_filesz;
bss.size = phdr.p_memsz - phdr.p_filesz;
bss.fileImage = NULL;
}
// Check to see if this is the text or data segment
if (phdr.p_vaddr <= text_sec_start &&
phdr.p_vaddr + phdr.p_filesz > text_sec_start) {
// If this value is nonzero, we need to flip the relocate flag.
if (phdr.p_vaddr != 0)
relocate = false;
text.baseAddr = phdr.p_paddr;
text.size = phdr.p_filesz;
text.fileImage = fileData + phdr.p_offset;
} else if (phdr.p_vaddr <= data_sec_start &&
phdr.p_vaddr + phdr.p_filesz > data_sec_start) {
data.baseAddr = phdr.p_paddr;
data.size = phdr.p_filesz;
data.fileImage = fileData + phdr.p_offset;
} else {
// If it's none of the above but is loadable,
// load the filesize worth of data
Segment extra;
extra.baseAddr = phdr.p_paddr;
extra.size = phdr.p_filesz;
extra.fileImage = fileData + phdr.p_offset;
extraSegments.push_back(extra);
}
}
// should have found at least one loadable segment
warn_if(text.size == 0,
"Empty .text segment in '%s'. ELF file corrupted?\n",
filename);
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, Addr mask,
Addr base, Addr offset)
{
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 = elf_memory((char*)fileData,len);
assert(elf != NULL);
// Get the first section
int sec_idx = 1; // there is a 0 but it is nothing, go figure
Elf_Scn *section = elf_getscn(elf, sec_idx);
// While there are no more sections
bool found = false;
while (section != NULL) {
GElf_Shdr shdr;
gelf_getshdr(section, &shdr);
if (shdr.sh_type == SHT_SYMTAB) {
found = true;
Elf_Data *data = elf_getdata(section, NULL);
int 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 (int i = 0; i < count; ++i) {
GElf_Sym sym;
gelf_getsym(data, i, &sym);
if (GELF_ST_BIND(sym.st_info) == binding) {
char *sym_name = elf_strptr(elf, shdr.sh_link, sym.st_name);
if (sym_name && sym_name[0] != '$') {
Addr value = sym.st_value - base + offset;
if (symtab->insert(value & mask, sym_name)) {
DPRINTF(Loader, "Symbol: %-40s value %#x\n",
sym_name, value);
}
}
}
}
}
++sec_idx;
section = elf_getscn(elf, sec_idx);
}
elf_end(elf);
return found;
}
bool
ElfObject::loadAllSymbols(SymbolTable *symtab, Addr base, Addr offset,
Addr addr_mask)
{
return (loadGlobalSymbols(symtab, base, offset, addr_mask) &&
loadLocalSymbols(symtab, base, offset, addr_mask) &&
loadWeakSymbols(symtab, base, offset, addr_mask));
}
bool
ElfObject::loadGlobalSymbols(SymbolTable *symtab, Addr base, Addr offset,
Addr addr_mask)
{
if (interpreter) {
interpreter->loadSomeSymbols(symtab, STB_GLOBAL, addr_mask,
base, offset);
}
return loadSomeSymbols(symtab, STB_GLOBAL, addr_mask, base, offset);
}
bool
ElfObject::loadLocalSymbols(SymbolTable *symtab, Addr base, Addr offset,
Addr addr_mask)
{
if (interpreter) {
interpreter->loadSomeSymbols(symtab, STB_LOCAL, addr_mask,
base, offset);
}
return loadSomeSymbols(symtab, STB_LOCAL, addr_mask, base, offset);
}
bool
ElfObject::loadWeakSymbols(SymbolTable *symtab, Addr base, Addr offset,
Addr addr_mask)
{
if (interpreter) {
interpreter->loadSomeSymbols(symtab, STB_WEAK, addr_mask,
base, offset);
}
return loadSomeSymbols(symtab, STB_WEAK, addr_mask, base, offset);
}
bool
ElfObject::loadSections(PortProxy& mem_proxy, Addr addr_mask, Addr offset)
{
if (!ObjectFile::loadSections(mem_proxy, addr_mask, offset))
return false;
for (auto seg : extraSegments) {
if (!loadSection(&seg, mem_proxy, addr_mask, offset)) {
return false;
}
}
if (interpreter)
interpreter->loadSections(mem_proxy, addr_mask, offset);
return true;
}
void
ElfObject::getSections()
{
assert(!sectionNames.size());
// 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 = elf_memory((char*)fileData,len);
assert(elf != NULL);
// Check that we actually have a elf file
GElf_Ehdr ehdr;
if (gelf_getehdr(elf, &ehdr) ==0) {
panic("Not ELF, shouldn't be here");
}
// Get the first section
int sec_idx = 1; // there is a 0 but it is nothing, go figure
Elf_Scn *section = elf_getscn(elf, sec_idx);
// While there are no more sections
while (section) {
GElf_Shdr shdr;
gelf_getshdr(section, &shdr);
sectionNames.insert(elf_strptr(elf, ehdr.e_shstrndx, shdr.sh_name));
section = elf_getscn(elf, ++sec_idx);
} // while sections
elf_end(elf);
}
bool
ElfObject::sectionExists(std::string sec)
{
if (!sectionNames.size())
getSections();
return sectionNames.find(sec) != sectionNames.end();
}
void
ElfObject::updateBias(Addr bias_addr)
{
// Record the bias.
ldBias = bias_addr;
// Patch the entry point with bias_addr.
entry += bias_addr;
// Patch segments with the bias_addr.
text.baseAddr += bias_addr;
data.baseAddr += bias_addr;
bss.baseAddr += bias_addr;
for (auto &segment : extraSegments)
segment.baseAddr += bias_addr;
}