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Don't iterate over the program headers in the constructor of ELFFile.

Browse Source 
Not every program needs this information.

In particular, it is necessary and sufficient for a static linker to scan the
section table.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242833 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola
2015-07-21 20:50:53 +00:00
parent 85223309d7
commit c22eb2bea6
2 changed files with 172 additions and 188 deletions
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170
include/llvm/Object/ELF.h
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@@ -157,23 +157,22 @@ public:
typedef iterator_range<const Elf_Sym *> Elf_Sym_Range;
const uint8_t *base() const {
return reinterpret_cast<const uint8_t *>(Buf.data());
}
private:
typedef SmallVector<const Elf_Shdr *, 2> Sections_t;
typedef DenseMap<unsigned, unsigned> IndexMap_t;
StringRef Buf;
const uint8_t *base() const {
return reinterpret_cast<const uint8_t *>(Buf.data());
}
const Elf_Ehdr *Header;
const Elf_Shdr *SectionHeaderTable = nullptr;
StringRef DotShstrtab; // Section header string table.
StringRef DotStrtab; // Symbol header string table.
const Elf_Shdr *dot_symtab_sec = nullptr; // Symbol table section.
const Elf_Shdr *DotDynSymSec = nullptr; // Dynamic symbol table section.
const Elf_Hash *HashTable = nullptr;
const Elf_Shdr *SymbolTableSectionHeaderIndex = nullptr;
DenseMap<const Elf_Sym *, ELF::Elf64_Word> ExtendedSymbolTable;
@@ -182,24 +181,6 @@ private:
const Elf_Shdr *dot_gnu_version_r_sec = nullptr; // .gnu.version_r
const Elf_Shdr *dot_gnu_version_d_sec = nullptr; // .gnu.version_d
/// \brief Represents a region described by entries in the .dynamic table.
struct DynRegionInfo {
DynRegionInfo() : Addr(nullptr), Size(0), EntSize(0) {}
/// \brief Address in current address space.
const void *Addr;
/// \brief Size in bytes of the region.
uintX_t Size;
/// \brief Size of each entity in the region.
uintX_t EntSize;
};
DynRegionInfo DynamicRegion;
DynRegionInfo DynStrRegion;
DynRegionInfo DynRelaRegion;
// SONAME entry in dynamic string table
StringRef DTSoname;
// Records for each version index the corresponding Verdef or Vernaux entry.
// This is filled the first time LoadVersionMap() is called.
class VersionMapEntry : public PointerIntPair<const void*, 1> {
@@ -226,8 +207,6 @@ private:
void LoadVersionNeeds(const Elf_Shdr *ec) const;
void LoadVersionMap() const;
void scanDynamicTable();
public:
template<typename T>
const T *getEntry(uint32_t Section, uint32_t Entry) const;
@@ -236,16 +215,11 @@ public:
const Elf_Shdr *getDotSymtabSec() const { return dot_symtab_sec; }
const Elf_Shdr *getDotDynSymSec() const { return DotDynSymSec; }
const Elf_Hash *getHashTable() const { return HashTable; }
StringRef getDynamicStringTable() const {
return StringRef((const char *)DynStrRegion.Addr, DynStrRegion.Size);
}
ErrorOr<StringRef> getStringTable(const Elf_Shdr *Section) const;
ErrorOr<StringRef> getStringTableForSymtab(const Elf_Shdr &Section) const;
const char *getDynamicString(uintX_t Offset) const;
ErrorOr<StringRef> getSymbolVersion(const Elf_Sym *Symb,
ErrorOr<StringRef> getSymbolVersion(StringRef StrTab, const Elf_Sym *Symb,
bool &IsDefault) const;
void VerifyStrTab(const Elf_Shdr *sh) const;
@@ -283,12 +257,6 @@ public:
return make_range(symbol_begin(), symbol_end());
}
const Elf_Dyn *dynamic_table_begin() const;
const Elf_Dyn *dynamic_table_end() const;
Elf_Dyn_Range dynamic_table() const {
return make_range(dynamic_table_begin(), dynamic_table_end());
}
const Elf_Sym *dynamic_symbol_begin() const {
if (!DotDynSymSec)
return nullptr;
@@ -308,25 +276,8 @@ public:
return make_range(dynamic_symbol_begin(), dynamic_symbol_end());
}
const Elf_Rela *dyn_rela_begin() const {
if (DynRelaRegion.Size && DynRelaRegion.EntSize != sizeof(Elf_Rela))
report_fatal_error("Invalid relocation entry size");
return reinterpret_cast<const Elf_Rela *>(DynRelaRegion.Addr);
}
const Elf_Rela *dyn_rela_end() const {
uint64_t Size = DynRelaRegion.Size;
if (Size % sizeof(Elf_Rela))
report_fatal_error("Invalid relocation table size");
return dyn_rela_begin() + Size / sizeof(Elf_Rela);
}
typedef iterator_range<const Elf_Rela *> Elf_Rela_Range;
Elf_Rela_Range dyn_relas() const {
return make_range(dyn_rela_begin(), dyn_rela_end());
}
const Elf_Rela *rela_begin(const Elf_Shdr *sec) const {
if (sec->sh_entsize != sizeof(Elf_Rela))
report_fatal_error("Invalid relocation entry size");
@@ -389,7 +340,6 @@ public:
ErrorOr<StringRef> getSectionName(const Elf_Shdr *Section) const;
ErrorOr<ArrayRef<uint8_t> > getSectionContents(const Elf_Shdr *Sec) const;
StringRef getLoadName() const;
};
typedef ELFFile<ELFType<support::little, false>> ELF32LEFile;
@@ -596,10 +546,8 @@ ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
Header = reinterpret_cast<const Elf_Ehdr *>(base());
if (Header->e_shoff == 0) {
scanDynamicTable();
if (Header->e_shoff == 0)
return;
}
const uint64_t SectionTableOffset = Header->e_shoff;
@@ -624,13 +572,6 @@ ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
for (const Elf_Shdr &Sec : sections()) {
switch (Sec.sh_type) {
case ELF::SHT_HASH:
if (HashTable) {
EC = object_error::parse_failed;
return;
}
HashTable = reinterpret_cast<const Elf_Hash *>(base() + Sec.sh_offset);
break;
case ELF::SHT_SYMTAB_SHNDX:
if (SymbolTableSectionHeaderIndex) {
// More than one .symtab_shndx!
@@ -708,8 +649,6 @@ ELFFile<ELFT>::ELFFile(StringRef Object, std::error_code &EC)
}
}
scanDynamicTable();
EC = std::error_code();
}
@@ -718,68 +657,6 @@ static bool compareAddr(uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
return VAddr < Phdr->p_vaddr;
}
template <class ELFT> void ELFFile<ELFT>::scanDynamicTable() {
SmallVector<const Elf_Phdr *, 4> LoadSegments;
for (const Elf_Phdr &Phdr : program_headers()) {
if (Phdr.p_type == ELF::PT_DYNAMIC) {
DynamicRegion.Addr = base() + Phdr.p_offset;
DynamicRegion.Size = Phdr.p_filesz;
continue;
}
if (Phdr.p_type != ELF::PT_LOAD || Phdr.p_filesz == 0)
continue;
LoadSegments.push_back(&Phdr);
}
auto toMappedAddr = [&](uint64_t VAddr) -> const uint8_t * {
const Elf_Phdr **I = std::upper_bound(
LoadSegments.begin(), LoadSegments.end(), VAddr, compareAddr<ELFT>);
if (I == LoadSegments.begin())
report_fatal_error("Virtual address is not in any segment");
--I;
const Elf_Phdr &Phdr = **I;
uint64_t Delta = VAddr - Phdr.p_vaddr;
if (Delta >= Phdr.p_filesz)
report_fatal_error("Virtual address is not in any segment");
return this->base() + Phdr.p_offset + Delta;
};
uint64_t SONameOffset = 0;
for (const Elf_Dyn &Dyn : dynamic_table()) {
switch (Dyn.d_tag) {
case ELF::DT_HASH:
if (HashTable)
continue;
HashTable =
reinterpret_cast<const Elf_Hash *>(toMappedAddr(Dyn.getPtr()));
break;
case ELF::DT_STRTAB:
if (!DynStrRegion.Addr)
DynStrRegion.Addr = toMappedAddr(Dyn.getPtr());
break;
case ELF::DT_STRSZ:
if (!DynStrRegion.Size)
DynStrRegion.Size = Dyn.getVal();
break;
case ELF::DT_RELA:
if (!DynRelaRegion.Addr)
DynRelaRegion.Addr = toMappedAddr(Dyn.getPtr());
break;
case ELF::DT_RELASZ:
DynRelaRegion.Size = Dyn.getVal();
break;
case ELF::DT_RELAENT:
DynRelaRegion.EntSize = Dyn.getVal();
break;
case ELF::DT_SONAME:
SONameOffset = Dyn.getVal();
break;
}
}
if (SONameOffset)
DTSoname = getDynamicString(SONameOffset);
}
template <class ELFT>
const typename ELFFile<ELFT>::Elf_Shdr *ELFFile<ELFT>::section_begin() const {
if (Header->e_shentsize != sizeof(Elf_Shdr))
@@ -810,27 +687,6 @@ const typename ELFFile<ELFT>::Elf_Sym *ELFFile<ELFT>::symbol_end() const {
dot_symtab_sec->sh_size);
}
template <class ELFT>
const typename ELFFile<ELFT>::Elf_Dyn *
ELFFile<ELFT>::dynamic_table_begin() const {
return reinterpret_cast<const Elf_Dyn *>(DynamicRegion.Addr);
}
template <class ELFT>
const typename ELFFile<ELFT>::Elf_Dyn *
ELFFile<ELFT>::dynamic_table_end() const {
uint64_t Size = DynamicRegion.Size;
if (Size % sizeof(Elf_Dyn))
report_fatal_error("Invalid dynamic table size");
return dynamic_table_begin() + Size / sizeof(Elf_Dyn);
}
template <class ELFT>
StringRef ELFFile<ELFT>::getLoadName() const {
return DTSoname;
}
template <class ELFT>
template <typename T>
const T *ELFFile<ELFT>::getEntry(uint32_t Section, uint32_t Entry) const {
@@ -886,13 +742,6 @@ ELFFile<ELFT>::getStringTableForSymtab(const Elf_Shdr &Sec) const {
return getStringTable(*SectionOrErr);
}
template <class ELFT>
const char *ELFFile<ELFT>::getDynamicString(uintX_t Offset) const {
if (Offset >= DynStrRegion.Size)
return nullptr;
return (const char *)DynStrRegion.Addr + Offset;
}
template <class ELFT>
ErrorOr<StringRef>
ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
@@ -903,7 +752,8 @@ ELFFile<ELFT>::getSectionName(const Elf_Shdr *Section) const {
}
template <class ELFT>
ErrorOr<StringRef> ELFFile<ELFT>::getSymbolVersion(const Elf_Sym *symb,
ErrorOr<StringRef> ELFFile<ELFT>::getSymbolVersion(StringRef StrTab,
const Elf_Sym *symb,
bool &IsDefault) const {
// This is a dynamic symbol. Look in the GNU symbol version table.
if (!dot_gnu_version_sec) {
@@ -951,9 +801,9 @@ ErrorOr<StringRef> ELFFile<ELFT>::getSymbolVersion(const Elf_Sym *symb,
IsDefault = false;
}
if (name_offset >= DynStrRegion.Size)
if (name_offset >= StrTab.size())
return object_error::parse_failed;
return StringRef(getDynamicString(name_offset));
return StringRef(StrTab.data() + name_offset);
}
/// This function returns the hash value for a symbol in the .dynsym section