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//===-- DyldELFObject.h - Dynamically loaded ELF object ----0---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Dynamically loaded ELF object class, a subclass of ELFObjectFile. Used
// to represent a loadable ELF image.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
#define LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
#include "llvm/Object/ELF.h"
namespace llvm {
using support::endianness;
using namespace llvm::object;
template<support::endianness target_endianness, bool is64Bits>
class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
typedef typename ELFObjectFile<target_endianness, is64Bits>::
Elf_Ehdr Elf_Ehdr;
Elf_Ehdr *Header;
// Update section headers according to the current location in memory
virtual void rebaseObject(std::vector<uint8_t*> *MemoryMap);
// Record memory addresses for cleanup
virtual void saveAddress(std::vector<uint8_t*> *MemoryMap, uint8_t *addr);
protected:
virtual error_code getSymbolAddress(DataRefImpl Symb, uint64_t &Res) const;
public:
DyldELFObject(MemoryBuffer *Object, std::vector<uint8_t*> *MemoryMap,
error_code &ec);
// Methods for type inquiry through isa, cast, and dyn_cast
static inline bool classof(const Binary *v) {
return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
&& classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
}
static inline bool classof(
const ELFObjectFile<target_endianness, is64Bits> *v) {
return v->isDyldType();
}
static inline bool classof(const DyldELFObject *v) {
return true;
}
};
template<support::endianness target_endianness, bool is64Bits>
DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Object,
std::vector<uint8_t*> *MemoryMap, error_code &ec)
: ELFObjectFile<target_endianness, is64Bits>(Object, ec)
, Header(0) {
this->isDyldELFObject = true;
Header = const_cast<Elf_Ehdr *>(
reinterpret_cast<const Elf_Ehdr *>(this->base()));
if (Header->e_shoff == 0)
return;
// Mark the image as a dynamic shared library
Header->e_type = ELF::ET_DYN;
rebaseObject(MemoryMap);
}
// Walk through the ELF headers, updating virtual addresses to reflect where
// the object is currently loaded in memory
template<support::endianness target_endianness, bool is64Bits>
void DyldELFObject<target_endianness, is64Bits>::rebaseObject(
std::vector<uint8_t*> *MemoryMap) {
typedef typename ELFDataTypeTypedefHelper<
target_endianness, is64Bits>::value_type addr_type;
uint8_t *base_p = const_cast<uint8_t *>(this->base());
Elf_Shdr *sectionTable =
reinterpret_cast<Elf_Shdr *>(base_p + Header->e_shoff);
uint64_t numSections = this->getNumSections();
// Allocate memory space for NOBITS sections (such as .bss), which only exist
// in memory, but don't occupy space in the object file.
// Update the address in the section headers to reflect this allocation.
for (uint64_t index = 0; index < numSections; index++) {
Elf_Shdr *sec = reinterpret_cast<Elf_Shdr *>(
reinterpret_cast<char *>(sectionTable) + index * Header->e_shentsize);
// Only update sections that are meant to be present in program memory
if (sec->sh_flags & ELF::SHF_ALLOC) {
uint8_t *addr = base_p + sec->sh_offset;
if (sec->sh_type == ELF::SHT_NOBITS) {
addr = static_cast<uint8_t *>(calloc(sec->sh_size, 1));
saveAddress(MemoryMap, addr);
}
else {
// FIXME: Currently memory with RWX permissions is allocated. In the
// future, make sure that permissions are as necessary
if (sec->sh_flags & ELF::SHF_WRITE) {
// see FIXME above
}
if (sec->sh_flags & ELF::SHF_EXECINSTR) {
// see FIXME above
}
}
assert(sizeof(addr_type) == sizeof(intptr_t) &&
"Cross-architecture ELF dy-load is not supported!");
sec->sh_addr = static_cast<addr_type>(intptr_t(addr));
}
}
// Now allocate actual space for COMMON symbols, which also don't occupy
// space in the object file.
// We want to allocate space for all COMMON symbols at once, so the flow is:
// 1. Go over all symbols, find those that are in COMMON. For each such
// symbol, record its size and the value field in its symbol header in a
// special vector.
// 2. Allocate memory for all COMMON symbols in one fell swoop.
// 3. Using the recorded information from (1), update the address fields in
// the symbol headers of the COMMON symbols to reflect their allocated
// address.
uint64_t TotalSize = 0;
std::vector<std::pair<Elf_Addr *, uint64_t> > SymbAddrInfo;
error_code ec = object_error::success;
for (symbol_iterator si = this->begin_symbols(),
se = this->end_symbols(); si != se; si.increment(ec)) {
uint64_t Size = 0;
ec = si->getSize(Size);
Elf_Sym* symb = const_cast<Elf_Sym*>(
this->getSymbol(si->getRawDataRefImpl()));
if (ec == object_error::success &&
this->getSymbolTableIndex(symb) == ELF::SHN_COMMON && Size > 0) {
SymbAddrInfo.push_back(std::make_pair(&(symb->st_value), Size));
TotalSize += Size;
}
}
uint8_t* SectionPtr = (uint8_t *)calloc(TotalSize, 1);
saveAddress(MemoryMap, SectionPtr);
typedef typename std::vector<std::pair<Elf_Addr *, uint64_t> >::iterator
AddrInfoIterator;
AddrInfoIterator EndIter = SymbAddrInfo.end();
for (AddrInfoIterator AddrIter = SymbAddrInfo.begin();
AddrIter != EndIter; ++AddrIter) {
assert(sizeof(addr_type) == sizeof(intptr_t) &&
"Cross-architecture ELF dy-load is not supported!");
*(AddrIter->first) = static_cast<addr_type>(intptr_t(SectionPtr));
SectionPtr += AddrIter->second;
}
}
// Record memory addresses for callers
template<support::endianness target_endianness, bool is64Bits>
void DyldELFObject<target_endianness, is64Bits>::saveAddress(
std::vector<uint8_t*> *MemoryMap, uint8_t* addr) {
if (MemoryMap)
MemoryMap->push_back(addr);
else
errs() << "WARNING: Memory leak - cannot record memory for ELF dyld.";
}
template<support::endianness target_endianness, bool is64Bits>
error_code DyldELFObject<target_endianness, is64Bits>::getSymbolAddress(
DataRefImpl Symb, uint64_t &Result) const {
this->validateSymbol(Symb);
const Elf_Sym *symb = this->getSymbol(Symb);
if (this->getSymbolTableIndex(symb) == ELF::SHN_COMMON) {
Result = symb->st_value;
return object_error::success;
}
else {
return ELFObjectFile<target_endianness, is64Bits>::getSymbolAddress(
Symb, Result);
}
}
}
#endif
//===-- DyldELFObject.h - Dynamically loaded ELF object ----0---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Dynamically loaded ELF object class, a subclass of ELFObjectFile. Used
// to represent a loadable ELF image.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
#define LLVM_RUNTIMEDYLD_DYLDELFOBJECT_H
#include "llvm/Object/ELF.h"
namespace llvm {
using support::endianness;
using namespace llvm::object;
template<support::endianness target_endianness, bool is64Bits>
class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
typedef typename ELFObjectFile<target_endianness, is64Bits>::
Elf_Ehdr Elf_Ehdr;
Elf_Ehdr *Header;
// Update section headers according to the current location in memory
virtual void rebaseObject(std::vector<uint8_t*> *MemoryMap);
// Record memory addresses for cleanup
virtual void saveAddress(std::vector<uint8_t*> *MemoryMap, uint8_t *addr);
protected:
virtual error_code getSymbolAddress(DataRefImpl Symb, uint64_t &Res) const;
public:
DyldELFObject(MemoryBuffer *Object, std::vector<uint8_t*> *MemoryMap,
error_code &ec);
// Methods for type inquiry through isa, cast, and dyn_cast
static inline bool classof(const Binary *v) {
return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
&& classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
}
static inline bool classof(
const ELFObjectFile<target_endianness, is64Bits> *v) {
return v->isDyldType();
}
static inline bool classof(const DyldELFObject *v) {
return true;
}
};
template<support::endianness target_endianness, bool is64Bits>
DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Object,
std::vector<uint8_t*> *MemoryMap, error_code &ec)
: ELFObjectFile<target_endianness, is64Bits>(Object, ec)
, Header(0) {
this->isDyldELFObject = true;
Header = const_cast<Elf_Ehdr *>(
reinterpret_cast<const Elf_Ehdr *>(this->base()));
if (Header->e_shoff == 0)
return;
// Mark the image as a dynamic shared library
Header->e_type = ELF::ET_DYN;
rebaseObject(MemoryMap);
}
// Walk through the ELF headers, updating virtual addresses to reflect where
// the object is currently loaded in memory
template<support::endianness target_endianness, bool is64Bits>
void DyldELFObject<target_endianness, is64Bits>::rebaseObject(
std::vector<uint8_t*> *MemoryMap) {
typedef typename ELFDataTypeTypedefHelper<
target_endianness, is64Bits>::value_type addr_type;
uint8_t *base_p = const_cast<uint8_t *>(this->base());
Elf_Shdr *sectionTable =
reinterpret_cast<Elf_Shdr *>(base_p + Header->e_shoff);
uint64_t numSections = this->getNumSections();
// Allocate memory space for NOBITS sections (such as .bss), which only exist
// in memory, but don't occupy space in the object file.
// Update the address in the section headers to reflect this allocation.
for (uint64_t index = 0; index < numSections; index++) {
Elf_Shdr *sec = reinterpret_cast<Elf_Shdr *>(
reinterpret_cast<char *>(sectionTable) + index * Header->e_shentsize);
// Only update sections that are meant to be present in program memory
if (sec->sh_flags & ELF::SHF_ALLOC) {
uint8_t *addr = base_p + sec->sh_offset;
if (sec->sh_type == ELF::SHT_NOBITS) {
addr = static_cast<uint8_t *>(calloc(sec->sh_size, 1));
saveAddress(MemoryMap, addr);
}
else {
// FIXME: Currently memory with RWX permissions is allocated. In the
// future, make sure that permissions are as necessary
if (sec->sh_flags & ELF::SHF_WRITE) {
// see FIXME above
}
if (sec->sh_flags & ELF::SHF_EXECINSTR) {
// see FIXME above
}
}
assert(sizeof(addr_type) == sizeof(intptr_t) &&
"Cross-architecture ELF dy-load is not supported!");
sec->sh_addr = static_cast<addr_type>(intptr_t(addr));
}
}
// Now allocate actual space for COMMON symbols, which also don't occupy
// space in the object file.
// We want to allocate space for all COMMON symbols at once, so the flow is:
// 1. Go over all symbols, find those that are in COMMON. For each such
// symbol, record its size and the value field in its symbol header in a
// special vector.
// 2. Allocate memory for all COMMON symbols in one fell swoop.
// 3. Using the recorded information from (1), update the address fields in
// the symbol headers of the COMMON symbols to reflect their allocated
// address.
uint64_t TotalSize = 0;
std::vector<std::pair<Elf_Addr *, uint64_t> > SymbAddrInfo;
error_code ec = object_error::success;
for (symbol_iterator si = this->begin_symbols(),
se = this->end_symbols(); si != se; si.increment(ec)) {
uint64_t Size = 0;
ec = si->getSize(Size);
Elf_Sym* symb = const_cast<Elf_Sym*>(
this->getSymbol(si->getRawDataRefImpl()));
if (ec == object_error::success &&
this->getSymbolTableIndex(symb) == ELF::SHN_COMMON && Size > 0) {
SymbAddrInfo.push_back(std::make_pair(&(symb->st_value), Size));
TotalSize += Size;
}
}
uint8_t* SectionPtr = (uint8_t *)calloc(TotalSize, 1);
saveAddress(MemoryMap, SectionPtr);
typedef typename std::vector<std::pair<Elf_Addr *, uint64_t> >::iterator
AddrInfoIterator;
AddrInfoIterator EndIter = SymbAddrInfo.end();
for (AddrInfoIterator AddrIter = SymbAddrInfo.begin();
AddrIter != EndIter; ++AddrIter) {
assert(sizeof(addr_type) == sizeof(intptr_t) &&
"Cross-architecture ELF dy-load is not supported!");
*(AddrIter->first) = static_cast<addr_type>(intptr_t(SectionPtr));
SectionPtr += AddrIter->second;
}
}
// Record memory addresses for callers
template<support::endianness target_endianness, bool is64Bits>
void DyldELFObject<target_endianness, is64Bits>::saveAddress(
std::vector<uint8_t*> *MemoryMap, uint8_t* addr) {
if (MemoryMap)
MemoryMap->push_back(addr);
else
errs() << "WARNING: Memory leak - cannot record memory for ELF dyld.";
}
template<support::endianness target_endianness, bool is64Bits>
error_code DyldELFObject<target_endianness, is64Bits>::getSymbolAddress(
DataRefImpl Symb, uint64_t &Result) const {
this->validateSymbol(Symb);
const Elf_Sym *symb = this->getSymbol(Symb);
if (this->getSymbolTableIndex(symb) == ELF::SHN_COMMON) {
Result = symb->st_value;
return object_error::success;
}
else {
return ELFObjectFile<target_endianness, is64Bits>::getSymbolAddress(
Symb, Result);
}
}
}
#endif
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