[llvm] r287786 - llvm-readobj: Use hash tables to print dynamic symbols.
Davide Italiano via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 23 11:02:48 PST 2016
On Wed, Nov 23, 2016 at 10:04 AM, Hemant Kulkarni via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: khemant
> Date: Wed Nov 23 12:04:23 2016
> New Revision: 287786
>
> URL: http://llvm.org/viewvc/llvm-project?rev=287786&view=rev
> Log:
> llvm-readobj: Use hash tables to print dynamic symbols.
>
> -symbols prints both .symtab and .dynsym symbols for GNU style in ELF.
> -dyn-symbols prints symbols looking up through hash tables. This helps validate hash tables.
>
hrmm, what's the rationale behind this change? Are you trying to be
compatible with what GNU objdump produces or what?
Maybe next time you can discuss it first or send a review? There are
many people who can review (me/Michael/Eric/Rafael etc..).
> Modified:
> llvm/trunk/test/tools/llvm-readobj/gnu-symbols.test
> llvm/trunk/tools/llvm-readobj/ELFDumper.cpp
>
> Modified: llvm/trunk/test/tools/llvm-readobj/gnu-symbols.test
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-readobj/gnu-symbols.test?rev=287786&r1=287785&r2=287786&view=diff
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-readobj/gnu-symbols.test (original)
> +++ llvm/trunk/test/tools/llvm-readobj/gnu-symbols.test Wed Nov 23 12:04:23 2016
> @@ -4,6 +4,8 @@ RUN: llvm-readobj -symbols %p/Inputs/rel
> RUN: | FileCheck %s -check-prefix ELF64
> RUN: llvm-readobj -symbols %p/Inputs/gnuhash.so.elf-x86_64 --elf-output-style=GNU \
> RUN: | FileCheck %s -check-prefix DYN
> +RUN: llvm-readobj -dyn-symbols %p/Inputs/dynamic-table-exe.x86 --elf-output-style=GNU \
> +RUN: | FileCheck %s -check-prefix HASH
>
> ELF32: Symbol table '.symtab' contains 5 entries:
> ELF32-NEXT: Num: Value Size Type Bind Vis Ndx Name
> @@ -44,3 +46,29 @@ DYN-NEXT: 8: 0000000000200268 0
> DYN-NEXT: 9: 00000000000001b8 0 NOTYPE GLOBAL DEFAULT 4 foo
> DYN-NEXT: 10: 0000000000200268 0 NOTYPE GLOBAL DEFAULT 5 _edata
> DYN-NEXT: 11: 0000000000200268 0 NOTYPE GLOBAL DEFAULT 5 _end
> +
> +HASH: Symbol table of .hash for image:
> +HASH-NEXT: Num Buc: Value Size Type Bind Vis Ndx Name
> +HASH-NEXT: 9 0: 00000000 0 FUNC GLOBAL DEFAULT UND __gxx_personality_v0 at CXXABI_1.3
> +HASH-NEXT: 13 0: 00001b64 0 NOTYPE GLOBAL DEFAULT ABS _edata@
> +HASH-NEXT: 7 0: 00000000 0 FUNC GLOBAL DEFAULT UND _ZNSt14basic_ifstreamIcSt11char_traitsIcEEC1EPKcSt13_Ios_Openmode at GLIBCXX_3.4
> +HASH-NEXT: 2 0: 00000000 0 NOTYPE WEAK DEFAULT UND _Jv_RegisterClasses@
> +HASH-NEXT: 1 0: 00000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__@
> +HASH-NEXT: 16 1: 00000850 81 FUNC GLOBAL DEFAULT 14 main@
> +HASH-NEXT: 10 1: 00000000 0 FUNC GLOBAL DEFAULT UND _Unwind_Resume at GCC_3.0
> +HASH-NEXT: 8 1: 00000000 0 FUNC GLOBAL DEFAULT UND puts at GLIBC_2.0
> +HASH-NEXT: 12 1: 00001b68 0 NOTYPE GLOBAL DEFAULT ABS _end@
> +HASH-NEXT: 6 1: 00000000 0 FUNC GLOBAL DEFAULT UND _ZNSt14basic_ifstreamIcSt11char_traitsIcEED1Ev at GLIBCXX_3.4
> +HASH-NEXT: 5 1: 00000000 0 NOTYPE WEAK DEFAULT UND _ITM_registerTMCloneTable@
> +HASH-NEXT: 4 1: 00000000 0 NOTYPE WEAK DEFAULT UND _ITM_deregisterTMCloneTable@
> +HASH-NEXT: 3 1: 00000000 0 FUNC GLOBAL DEFAULT UND __libc_start_main at GLIBC_2.0
> +HASH-NEXT: 11 2: 00000000 0 FUNC WEAK DEFAULT UND __cxa_finalize at GLIBC_2.1.3
> +HASH-NEXT: 15 2: 00001b64 0 NOTYPE GLOBAL DEFAULT ABS __bss_start@
> +HASH-NEXT: 14 2: 0000093c 4 OBJECT GLOBAL DEFAULT 16 _IO_stdin_used@
> +HASH: Symbol table of .gnu.hash for image:
> +HASH-NEXT: Num Buc: Value Size Type Bind Vis Ndx Name
> +HASH-NEXT: 12 0: 00001b68 0 NOTYPE GLOBAL DEFAULT ABS _end@
> +HASH-NEXT: 13 0: 00001b64 0 NOTYPE GLOBAL DEFAULT ABS _edata@
> +HASH-NEXT: 14 1: 0000093c 4 OBJECT GLOBAL DEFAULT 16 _IO_stdin_used@
> +HASH-NEXT: 15 1: 00001b64 0 NOTYPE GLOBAL DEFAULT ABS __bss_start@
> +HASH-NEXT: 16 1: 00000850 81 FUNC GLOBAL DEFAULT 14 main@
>
> Modified: llvm/trunk/tools/llvm-readobj/ELFDumper.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-readobj/ELFDumper.cpp?rev=287786&r1=287785&r2=287786&view=diff
> ==============================================================================
> --- llvm/trunk/tools/llvm-readobj/ELFDumper.cpp (original)
> +++ llvm/trunk/tools/llvm-readobj/ELFDumper.cpp Wed Nov 23 12:04:23 2016
> @@ -328,6 +328,8 @@ private:
> OS.flush();
> return OS;
> }
> + void printHashedSymbol(const ELFO *Obj, const Elf_Sym *FirstSym, uint32_t Sym,
> + StringRef StrTable, uint32_t Bucket);
> void printRelocation(const ELFO *Obj, const Elf_Shdr *SymTab,
> const Elf_Rela &R, bool IsRela);
> void printSymbol(const ELFO *Obj, const Elf_Sym *Symbol, const Elf_Sym *First,
> @@ -2812,15 +2814,120 @@ void GNUStyle<ELFT>::printSymbol(const E
> printField(Entry);
> OS << "\n";
> }
> +template <class ELFT>
> +void GNUStyle<ELFT>::printHashedSymbol(const ELFO *Obj, const Elf_Sym *FirstSym,
> + uint32_t Sym, StringRef StrTable,
> + uint32_t Bucket) {
> + std::string Num, Buc, Name, Value, Size, Binding, Type, Visibility, Section;
> + unsigned Width, Bias = 0;
> + if (ELFT::Is64Bits) {
> + Bias = 8;
> + Width = 16;
> + } else {
> + Bias = 0;
> + Width = 8;
> + }
> + Field Fields[9] = {0, 6, 11, 20 + Bias, 25 + Bias,
> + 34 + Bias, 41 + Bias, 49 + Bias, 53 + Bias};
> + Num = to_string(format_decimal(Sym, 5));
> + Buc = to_string(format_decimal(Bucket, 3)) + ":";
> +
> + const auto Symbol = FirstSym + Sym;
> + Value = to_string(format_hex_no_prefix(Symbol->st_value, Width));
> + Size = to_string(format_decimal(Symbol->st_size, 5));
> + unsigned char SymbolType = Symbol->getType();
> + if (Obj->getHeader()->e_machine == ELF::EM_AMDGPU &&
> + SymbolType >= ELF::STT_LOOS && SymbolType < ELF::STT_HIOS)
> + Type = printEnum(SymbolType, makeArrayRef(AMDGPUSymbolTypes));
> + else
> + Type = printEnum(SymbolType, makeArrayRef(ElfSymbolTypes));
> + unsigned Vis = Symbol->getVisibility();
> + Binding = printEnum(Symbol->getBinding(), makeArrayRef(ElfSymbolBindings));
> + Visibility = printEnum(Vis, makeArrayRef(ElfSymbolVisibilities));
> + Section = getSymbolSectionNdx(Obj, Symbol, FirstSym);
> + Name = this->dumper()->getFullSymbolName(Symbol, StrTable, true);
> + Fields[0].Str = Num;
> + Fields[1].Str = Buc;
> + Fields[2].Str = Value;
> + Fields[3].Str = Size;
> + Fields[4].Str = Type;
> + Fields[5].Str = Binding;
> + Fields[6].Str = Visibility;
> + Fields[7].Str = Section;
> + Fields[8].Str = Name;
> + for (auto &Entry : Fields)
> + printField(Entry);
> + OS << "\n";
> +}
>
> template <class ELFT> void GNUStyle<ELFT>::printSymbols(const ELFO *Obj) {
> + if (opts::DynamicSymbols)
> + return;
> this->dumper()->printSymbolsHelper(true);
> this->dumper()->printSymbolsHelper(false);
> }
>
> template <class ELFT>
> void GNUStyle<ELFT>::printDynamicSymbols(const ELFO *Obj) {
> - this->dumper()->printSymbolsHelper(true);
> + if (this->dumper()->getDynamicStringTable().size() == 0)
> + return;
> + auto StringTable = this->dumper()->getDynamicStringTable();
> + auto DynSyms = this->dumper()->dynamic_symbols();
> + auto GnuHash = this->dumper()->getGnuHashTable();
> + auto SysVHash = this->dumper()->getHashTable();
> +
> + // If no hash or .gnu.hash found, try using symbol table
> + if (GnuHash == nullptr && SysVHash == nullptr)
> + this->dumper()->printSymbolsHelper(true);
> +
> + // Try printing .hash
> + if (this->dumper()->getHashTable()) {
> + OS << "\n Symbol table of .hash for image:\n";
> + if (ELFT::Is64Bits)
> + OS << " Num Buc: Value Size Type Bind Vis Ndx Name";
> + else
> + OS << " Num Buc: Value Size Type Bind Vis Ndx Name";
> + OS << "\n";
> +
> + uint32_t NBuckets = SysVHash->nbucket;
> + uint32_t NChains = SysVHash->nchain;
> + auto Buckets = SysVHash->buckets();
> + auto Chains = SysVHash->chains();
> + for (uint32_t Buc = 0; Buc < NBuckets; Buc++) {
> + if (Buckets[Buc] == ELF::STN_UNDEF)
> + continue;
> + for (uint32_t Ch = Buckets[Buc]; Ch < NChains; Ch = Chains[Ch]) {
> + if (Ch == ELF::STN_UNDEF)
> + break;
> + printHashedSymbol(Obj, &DynSyms[0], Ch, StringTable, Buc);
> + }
> + }
> + }
> +
> + // Try printing .gnu.hash
> + if (GnuHash) {
> + OS << "\n Symbol table of .gnu.hash for image:\n";
> + if (ELFT::Is64Bits)
> + OS << " Num Buc: Value Size Type Bind Vis Ndx Name";
> + else
> + OS << " Num Buc: Value Size Type Bind Vis Ndx Name";
> + OS << "\n";
> + uint32_t NBuckets = GnuHash->nbuckets;
> + auto Buckets = GnuHash->buckets();
> + for (uint32_t Buc = 0; Buc < NBuckets; Buc++) {
> + if (Buckets[Buc] == ELF::STN_UNDEF)
> + continue;
> + uint32_t Index = Buckets[Buc];
> + uint32_t GnuHashable = Index - GnuHash->symndx;
> + // Print whole chain
> + while (true) {
> + printHashedSymbol(Obj, &DynSyms[0], Index++, StringTable, Buc);
> + // Chain ends at symbol with stopper bit
> + if ((GnuHash->values(DynSyms.size())[GnuHashable++] & 1) == 1)
> + break;
> + }
> + }
> + }
> }
>
> static inline std::string printPhdrFlags(unsigned Flag) {
>
>
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--
Davide
"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare
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