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Change how readobj stores info about dynamic symbols.

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We used to keep both a section and a pointer to the first symbol.

The oddity of keeping a section for dynamic symbols is because there is
a DT_SYMTAB but no DT_SYMTABZ, so to print the table we have to find the
size via a section table.

The reason for still keeping a pointer to the first symbol is because we
want to be able to print relocation tables even if the section table is
missing (it is mandatory only for files used in linking).

With this patch we keep just a DynRegionInfo. This then requires
changing a few places that were asking for a Elf_Shdr but actually just
needed the first symbol.

The test change is to delete the program header pointer.
Now that we use the information of both DT_SYMTAB and .dynsym, we don't
depend on the sh_entsize of .dynsym if we see DT_SYMTAB.

Note: It is questionable if it is worth it putting the effort to report
broken sh_entsize given that in files with no section table we have to
assume it is sizeof(Elf_Sym), but that is for another change.

Extracted from r260488.

llvm-svn: 261099
This commit is contained in:
Rafael Espindola 2016-02-17 15:38:21 +00:00
parent cacffaaf70
commit 6da20ee54a
4 changed files with 77 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
include/llvm/Object/ELF.h
View File

@ -200,6 +200,9 @@ public:
uint32_t getExtendedSymbolTableIndex(const Elf_Sym *Sym,
const Elf_Shdr *SymTab,
ArrayRef<Elf_Word> ShndxTable) const;
uint32_t getExtendedSymbolTableIndex(const Elf_Sym *Sym,
const Elf_Sym *FirstSym,
ArrayRef<Elf_Word> ShndxTable) const;
const Elf_Ehdr *getHeader() const { return Header; }
ErrorOr<const Elf_Shdr *> getSection(const Elf_Sym *Sym,
const Elf_Shdr *SymTab,
@ -225,8 +228,15 @@ template <class ELFT>
uint32_t ELFFile<ELFT>::getExtendedSymbolTableIndex(
const Elf_Sym *Sym, const Elf_Shdr *SymTab,
ArrayRef<Elf_Word> ShndxTable) const {
return getExtendedSymbolTableIndex(Sym, symbol_begin(SymTab), ShndxTable);
}
template <class ELFT>
uint32_t ELFFile<ELFT>::getExtendedSymbolTableIndex(
const Elf_Sym *Sym, const Elf_Sym *FirstSym,
ArrayRef<Elf_Word> ShndxTable) const {
assert(Sym->st_shndx == ELF::SHN_XINDEX);
unsigned Index = Sym - symbol_begin(SymTab);
unsigned Index = Sym - FirstSym;
// The size of the table was checked in getSHNDXTable.
return ShndxTable[Index];

BIN
test/Object/Inputs/invalid-sh_entsize.elf
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Binary file not shown.

4
test/Object/invalid.test
View File

@ -35,9 +35,11 @@ SECTION-NEXT: AddressAlignment:
SECTION-NEXT: EntrySize: 32
RUN: not llvm-readobj -t %p/Inputs/invalid-sh_entsize.elf 2>&1 | FileCheck --check-prefix=INVALID-SYM-SIZE %s
RUN: not llvm-readobj --dyn-symbols %p/Inputs/invalid-sh_entsize.elf 2>&1 | FileCheck --check-prefix=INVALID-SYM-SIZE %s
INVALID-SYM-SIZE: Invalid symbol size
RUN: not llvm-readobj --dyn-symbols %p/Inputs/invalid-sh_entsize.elf 2>&1 | FileCheck --check-prefix=INVALID-DYNSYM-SIZE %s
INVALID-DYNSYM-SIZE: Invalid entity size
RUN: not llvm-readobj -t %p/Inputs/invalid-section-index.elf 2>&1 | FileCheck --check-prefix=INVALID-SECTION-INDEX %s
INVALID-SECTION-INDEX: Invalid section index

107
tools/llvm-readobj/ELFDumper.cpp
View File

@ -48,9 +48,14 @@ namespace {
template <class ELFT> class DumpStyle;
/// \brief Represents a region described by entries in the .dynamic table.
/// Represents a contiguous uniform range in the file. We cannot just create a
/// range directly because when creating one of these from the .dynamic table
/// the size, entity size and virtual address are different entries in arbitrary
/// order (DT_REL, DT_RELSZ, DT_RELENT for example).
struct DynRegionInfo {
DynRegionInfo() : Addr(nullptr), Size(0), EntSize(0) {}
DynRegionInfo(const void *A, uint64_t S, uint64_t ES)
: Addr(A), Size(S), EntSize(ES) {}
/// \brief Address in current address space.
const void *Addr;
/// \brief Size in bytes of the region.
@ -102,6 +107,7 @@ private:
typedef ELFFile<ELFT> ELFO;
typedef typename ELFO::Elf_Shdr Elf_Shdr;
typedef typename ELFO::Elf_Sym Elf_Sym;
typedef typename ELFO::Elf_Sym_Range Elf_Sym_Range;
typedef typename ELFO::Elf_Dyn Elf_Dyn;
typedef typename ELFO::Elf_Dyn_Range Elf_Dyn_Range;
typedef typename ELFO::Elf_Rel Elf_Rel;
@ -121,10 +127,14 @@ private:
typedef typename ELFO::Elf_Verdef Elf_Verdef;
typedef typename ELFO::Elf_Verdaux Elf_Verdaux;
DynRegionInfo createDRIFrom(const Elf_Shdr *S) {
return {Obj->base() + S->sh_offset, S->sh_size, S->sh_entsize};
}
void parseDynamicTable(ArrayRef<const Elf_Phdr *> LoadSegments);
void printSymbolsHelper(bool IsDynamic);
void printSymbol(const Elf_Sym *Symbol, const Elf_Shdr *SymTab,
void printSymbol(const Elf_Sym *Symbol, const Elf_Sym *FirstSym,
StringRef StrTable, bool IsDynamic);
void printDynamicRelocation(Elf_Rela Rel);
@ -155,13 +165,12 @@ private:
DynRegionInfo DynRelRegion;
DynRegionInfo DynRelaRegion;
DynRegionInfo DynPLTRelRegion;
DynRegionInfo DynSymRegion;
const Elf_Phdr *DynamicProgHeader = nullptr;
StringRef DynamicStringTable;
const Elf_Sym *DynSymStart = nullptr;
StringRef SOName;
const Elf_Hash *HashTable = nullptr;
const Elf_GnuHash *GnuHashTable = nullptr;
const Elf_Shdr *DotDynSymSec = nullptr;
const Elf_Shdr *DotSymtabSec = nullptr;
ArrayRef<Elf_Word> ShndxTable;
@ -199,11 +208,15 @@ public:
return *Ret;
}
Elf_Sym_Range dynamic_symbols() const {
return DynSymRegion.getAsRange<Elf_Sym>();
}
std::string getFullSymbolName(const Elf_Sym *Symbol, StringRef StrTable,
bool IsDynamic);
const Elf_Shdr *getDotDynSymSec() const { return DotDynSymSec; }
const Elf_Shdr *getDotSymtabSec() const { return DotSymtabSec; }
ArrayRef<Elf_Word> getShndxTable() { return ShndxTable; }
StringRef getDynamicStringTable() const { return DynamicStringTable; }
};
template <typename ELFT> class DumpStyle {
@ -346,7 +359,7 @@ void ELFDumper<ELFT>::LoadVersionDefs(const Elf_Shdr *sec) const {
template <class ELFT> void ELFDumper<ELFT>::LoadVersionMap() {
// If there is no dynamic symtab or version table, there is nothing to do.
if (!DynSymStart || !dot_gnu_version_sec)
if (!DynSymRegion.Addr || !dot_gnu_version_sec)
return;
// Has the VersionMap already been loaded?
@ -380,18 +393,15 @@ static void printVersionSymbolSection(ELFDumper<ELFT> *Dumper,
W.printHex("Offset", Sec->sh_offset);
W.printNumber("Link", Sec->sh_link);
const typename ELFO::Elf_Shdr *DynSymSec = Dumper->getDotDynSymSec();
const uint8_t *P = (const uint8_t *)Obj->base() + Sec->sh_offset;
ErrorOr<StringRef> StrTableOrErr =
Obj->getStringTableForSymtab(*DynSymSec);
error(StrTableOrErr.getError());
StringRef StrTable = Dumper->getDynamicStringTable();
// Same number of entries in the dynamic symbol table (DT_SYMTAB).
ListScope Syms(W, "Symbols");
for (const typename ELFO::Elf_Sym &Sym : Obj->symbols(DynSymSec)) {
for (const typename ELFO::Elf_Sym &Sym : Dumper->dynamic_symbols()) {
DictScope S(W, "Symbol");
std::string FullSymbolName =
Dumper->getFullSymbolName(&Sym, *StrTableOrErr, true /* IsDynamic */);
Dumper->getFullSymbolName(&Sym, StrTable, true /* IsDynamic */);
W.printNumber("Version", *P);
W.printString("Name", FullSymbolName);
P += sizeof(typename ELFO::Elf_Half);
@ -467,7 +477,7 @@ StringRef ELFDumper<ELFT>::getSymbolVersion(StringRef StrTab,
// Determine the position in the symbol table of this entry.
size_t entry_index = (reinterpret_cast<uintptr_t>(symb) -
reinterpret_cast<uintptr_t>(DynSymStart)) /
reinterpret_cast<uintptr_t>(DynSymRegion.Addr)) /
sizeof(Elf_Sym);
// Get the corresponding version index entry
@ -523,7 +533,7 @@ std::string ELFDumper<ELFT>::getFullSymbolName(const Elf_Sym *Symbol,
template <typename ELFO>
static void
getSectionNameIndex(const ELFO &Obj, const typename ELFO::Elf_Sym *Symbol,
const typename ELFO::Elf_Shdr *SymTab,
const typename ELFO::Elf_Sym *FirstSym,
ArrayRef<typename ELFO::Elf_Word> ShndxTable,
StringRef &SectionName, unsigned &SectionIndex) {
SectionIndex = Symbol->st_shndx;
@ -542,7 +552,7 @@ getSectionNameIndex(const ELFO &Obj, const typename ELFO::Elf_Sym *Symbol,
else {
if (SectionIndex == SHN_XINDEX)
SectionIndex =
Obj.getExtendedSymbolTableIndex(Symbol, SymTab, ShndxTable);
Obj.getExtendedSymbolTableIndex(Symbol, FirstSym, ShndxTable);
ErrorOr<const typename ELFO::Elf_Shdr *> Sec = Obj.getSection(SectionIndex);
error(Sec.getError());
SectionName = errorOrDefault(Obj.getSectionName(*Sec));
@ -1012,9 +1022,9 @@ ELFDumper<ELFT>::ELFDumper(const ELFFile<ELFT> *Obj, StreamWriter &Writer)
DotSymtabSec = &Sec;
break;
case ELF::SHT_DYNSYM:
if (DotDynSymSec != nullptr)
if (DynSymRegion.Size)
reportError("Multilpe SHT_DYNSYM");
DotDynSymSec = &Sec;
DynSymRegion = createDRIFrom(&Sec);
break;
case ELF::SHT_SYMTAB_SHNDX: {
ErrorOr<ArrayRef<Elf_Word>> TableOrErr = Obj->getSHNDXTable(Sec);
@ -1084,8 +1094,8 @@ void ELFDumper<ELFT>::parseDynamicTable(
StringTableSize = Dyn.getVal();
break;
case ELF::DT_SYMTAB:
DynSymStart =
reinterpret_cast<const Elf_Sym *>(toMappedAddr(Dyn.getPtr()));
DynSymRegion.Addr = toMappedAddr(Dyn.getPtr());
DynSymRegion.EntSize = sizeof(Elf_Sym);
break;
case ELF::DT_RELA:
DynRelaRegion.Addr = toMappedAddr(Dyn.getPtr());
@ -1213,7 +1223,7 @@ void ELFDumper<ELFT>::printSections() {
if (!SymSec)
continue;
if (*SymSec == &Sec)
printSymbol(&Sym, Symtab, StrTable, false);
printSymbol(&Sym, Obj->symbol_begin(Symtab), StrTable, false);
}
}
@ -1341,7 +1351,7 @@ void ELFDumper<ELFT>::printDynamicRelocation(Elf_Rela Rel) {
Obj->getRelocationTypeName(Rel.getType(Obj->isMips64EL()), RelocName);
StringRef SymbolName;
uint32_t SymIndex = Rel.getSymbol(Obj->isMips64EL());
const Elf_Sym *Sym = DynSymStart + SymIndex;
const Elf_Sym *Sym = dynamic_symbols().begin() + SymIndex;
SymbolName = errorOrDefault(Sym->getName(DynamicStringTable));
if (opts::ExpandRelocs) {
DictScope Group(W, "Relocation");
@ -1359,14 +1369,23 @@ void ELFDumper<ELFT>::printDynamicRelocation(Elf_Rela Rel) {
template<class ELFT>
void ELFDumper<ELFT>::printSymbolsHelper(bool IsDynamic) {
const Elf_Shdr *Symtab = (IsDynamic) ? DotDynSymSec : DotSymtabSec;
if (!Symtab)
return;
ErrorOr<StringRef> StrTableOrErr = Obj->getStringTableForSymtab(*Symtab);
error(StrTableOrErr.getError());
StringRef StrTable = *StrTableOrErr;
for (const Elf_Sym &Sym : Obj->symbols(Symtab))
printSymbol(&Sym, Symtab, StrTable, IsDynamic);
StringRef StrTable;
Elf_Sym_Range Syms(nullptr, nullptr);
if (IsDynamic) {
StrTable = DynamicStringTable;
Syms = dynamic_symbols();
} else {
if (!DotSymtabSec)
return;
ErrorOr<StringRef> StrTableOrErr =
Obj->getStringTableForSymtab(*DotSymtabSec);
error(StrTableOrErr.getError());
StrTable = *StrTableOrErr;
Syms = Obj->symbols(DotSymtabSec);
}
for (const Elf_Sym &Sym : Syms)
printSymbol(&Sym, Syms.begin(), StrTable, IsDynamic);
}
template<class ELFT>
@ -1382,11 +1401,12 @@ void ELFDumper<ELFT>::printDynamicSymbols() {
}
template <class ELFT>
void ELFDumper<ELFT>::printSymbol(const Elf_Sym *Symbol, const Elf_Shdr *SymTab,
StringRef StrTable, bool IsDynamic) {
void ELFDumper<ELFT>::printSymbol(const Elf_Sym *Symbol,
const Elf_Sym *FirstSym, StringRef StrTable,
bool IsDynamic) {
unsigned SectionIndex = 0;
StringRef SectionName;
getSectionNameIndex(*Obj, Symbol, SymTab, ShndxTable, SectionName,
getSectionNameIndex(*Obj, Symbol, FirstSym, ShndxTable, SectionName,
SectionIndex);
std::string FullSymbolName = getFullSymbolName(Symbol, StrTable, IsDynamic);
unsigned char SymbolType = Symbol->getType();
@ -1760,10 +1780,11 @@ void ELFDumper<ELFT>::printGnuHashTable() {
W.printNumber("Shift Count", GnuHashTable->shift2);
W.printHexList("Bloom Filter", GnuHashTable->filter());
W.printList("Buckets", GnuHashTable->buckets());
if (!DotDynSymSec)
Elf_Sym_Range Syms = dynamic_symbols();
unsigned NumSyms = std::distance(Syms.begin(), Syms.end());
if (!NumSyms)
reportError("No dynamic symbol section");
W.printHexList("Values",
GnuHashTable->values(DotDynSymSec->getEntityCount()));
W.printHexList("Values", GnuHashTable->values(NumSyms));
}
template <typename ELFT> void ELFDumper<ELFT>::printLoadName() {
@ -1891,11 +1912,9 @@ template <class ELFT> void MipsGOTParser<ELFT>::parseGOT() {
return;
}
const Elf_Shdr *DynSymSec = Dumper->getDotDynSymSec();
ErrorOr<StringRef> StrTable = Obj->getStringTableForSymtab(*DynSymSec);
error(StrTable.getError());
const Elf_Sym *DynSymBegin = Obj->symbol_begin(DynSymSec);
const Elf_Sym *DynSymEnd = Obj->symbol_end(DynSymSec);
StringRef StrTable = Dumper->getDynamicStringTable();
const Elf_Sym *DynSymBegin = Dumper->dynamic_symbols().begin();
const Elf_Sym *DynSymEnd = Dumper->dynamic_symbols().end();
std::size_t DynSymTotal = std::size_t(std::distance(DynSymBegin, DynSymEnd));
if (*DtGotSym > DynSymTotal)
@ -1955,8 +1974,8 @@ template <class ELFT> void MipsGOTParser<ELFT>::parseGOT() {
const Elf_Sym *GotDynSym = DynSymBegin + *DtGotSym;
for (; It != GotGlobalEnd; ++It) {
DictScope D(W, "Entry");
printGlobalGotEntry(GOTShdr->sh_addr, GotBegin, It, GotDynSym++,
*StrTable, true);
printGlobalGotEntry(GOTShdr->sh_addr, GotBegin, It, GotDynSym++, StrTable,
true);
}
}
@ -2059,7 +2078,7 @@ void MipsGOTParser<ELFT>::printGlobalGotEntry(
unsigned SectionIndex = 0;
StringRef SectionName;
getSectionNameIndex(*Obj, Sym, Dumper->getDotDynSymSec(),
getSectionNameIndex(*Obj, Sym, Dumper->dynamic_symbols().begin(),
Dumper->getShndxTable(), SectionName, SectionIndex);
W.printHex("Section", SectionName, SectionIndex);
@ -2093,7 +2112,7 @@ void MipsGOTParser<ELFT>::printPLTEntry(uint64_t PLTAddr,
unsigned SectionIndex = 0;
StringRef SectionName;
getSectionNameIndex(*Obj, Sym, Dumper->getDotDynSymSec(),
getSectionNameIndex(*Obj, Sym, Dumper->dynamic_symbols().begin(),
Dumper->getShndxTable(), SectionName, SectionIndex);
W.printHex("Section", SectionName, SectionIndex);