ELF: Create .gnu.version and .gnu.version_r sections when linking against versioned DSOs.

Differential Revision: http://reviews.llvm.org/D19464

llvm-svn: 267775
This commit is contained in:
Peter Collingbourne 2016-04-27 20:22:31 +00:00
parent a541320908
commit 21a12fc69a
11 changed files with 434 additions and 4 deletions

View File

@ -407,6 +407,12 @@ template <class ELFT> void SharedFile<ELFT>::parseSoName() {
case SHT_SYMTAB_SHNDX:
this->SymtabSHNDX = check(Obj.getSHNDXTable(Sec));
break;
case SHT_GNU_versym:
this->VersymSec = &Sec;
break;
case SHT_GNU_verdef:
this->VerdefSec = &Sec;
break;
}
}
@ -430,17 +436,70 @@ template <class ELFT> void SharedFile<ELFT>::parseSoName() {
}
}
// Parse the version definitions in the object file if present. Returns a vector
// whose nth element contains a pointer to the Elf_Verdef for version identifier
// n. Version identifiers that are not definitions map to nullptr. The array
// always has at least length 1.
template <class ELFT>
std::vector<const typename ELFT::Verdef *>
SharedFile<ELFT>::parseVerdefs(const Elf_Versym *&Versym) {
std::vector<const Elf_Verdef *> Verdefs(1);
// We only need to process symbol versions for this DSO if it has both a
// versym and a verdef section, which indicates that the DSO contains symbol
// version definitions.
if (!VersymSec || !VerdefSec)
return Verdefs;
// The location of the first global versym entry.
Versym = reinterpret_cast<const Elf_Versym *>(this->ELFObj.base() +
VersymSec->sh_offset) +
this->Symtab->sh_info;
// We cannot determine the largest verdef identifier without inspecting
// every Elf_Verdef, but both bfd and gold assign verdef identifiers
// sequentially starting from 1, so we predict that the largest identifier
// will be VerdefCount.
unsigned VerdefCount = VerdefSec->sh_info;
Verdefs.resize(VerdefCount + 1);
// Build the Verdefs array by following the chain of Elf_Verdef objects
// from the start of the .gnu.version_d section.
const uint8_t *Verdef = this->ELFObj.base() + VerdefSec->sh_offset;
for (unsigned I = 0; I != VerdefCount; ++I) {
auto *CurVerdef = reinterpret_cast<const Elf_Verdef *>(Verdef);
Verdef += CurVerdef->vd_next;
unsigned VerdefIndex = CurVerdef->vd_ndx;
if (Verdefs.size() <= VerdefIndex)
Verdefs.resize(VerdefIndex + 1);
Verdefs[VerdefIndex] = CurVerdef;
}
return Verdefs;
}
// Fully parse the shared object file. This must be called after parseSoName().
template <class ELFT> void SharedFile<ELFT>::parseRest() {
// Create mapping from version identifiers to Elf_Verdef entries.
const Elf_Versym *Versym = nullptr;
std::vector<const Elf_Verdef *> Verdefs = parseVerdefs(Versym);
Elf_Sym_Range Syms = this->getElfSymbols(true);
uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
SymbolBodies.reserve(NumSymbols);
for (const Elf_Sym &Sym : Syms) {
unsigned VersymIndex = 0;
if (Versym) {
VersymIndex = Versym->vs_index;
++Versym;
// Ignore local symbols and non-default versions.
if (VersymIndex == 0 || (VersymIndex & VERSYM_HIDDEN))
continue;
}
StringRef Name = check(Sym.getName(this->StringTable));
if (Sym.isUndefined())
Undefs.push_back(Name);
else
SymbolBodies.emplace_back(this, Name, Sym);
SymbolBodies.emplace_back(this, Name, Sym, Verdefs[VersymIndex]);
}
}

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@ -24,6 +24,8 @@
#include "llvm/Object/IRObjectFile.h"
#include "llvm/Support/StringSaver.h"
#include <map>
namespace lld {
namespace elf {
@ -245,10 +247,14 @@ template <class ELFT> class SharedFile : public ELFFileBase<ELFT> {
typedef typename ELFT::Sym Elf_Sym;
typedef typename ELFT::Word Elf_Word;
typedef typename ELFT::SymRange Elf_Sym_Range;
typedef typename ELFT::Versym Elf_Versym;
typedef typename ELFT::Verdef Elf_Verdef;
std::vector<SharedSymbol<ELFT>> SymbolBodies;
std::vector<StringRef> Undefs;
StringRef SoName;
const Elf_Shdr *VersymSec = nullptr;
const Elf_Shdr *VerdefSec = nullptr;
public:
StringRef getSoName() const { return SoName; }
@ -266,6 +272,19 @@ public:
void parseSoName();
void parseRest();
std::vector<const Elf_Verdef *> parseVerdefs(const Elf_Versym *&Versym);
struct NeededVer {
// The string table offset of the version name in the output file.
size_t StrTab;
// The version identifier for this version name.
uint16_t Index;
};
// Mapping from Elf_Verdef data structures to information about Elf_Vernaux
// data structures in the output file.
std::map<const Elf_Verdef *, NeededVer> VerdefMap;
// Used for --as-needed
bool AsNeeded = false;

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@ -654,6 +654,12 @@ template <class ELFT> void DynamicSection<ELFT>::finalize() {
if (!Config->Entry.empty())
Add({DT_DEBUG, (uint64_t)0});
if (size_t NeedNum = Out<ELFT>::VerNeed->getNeedNum()) {
Add({DT_VERSYM, Out<ELFT>::VerSym});
Add({DT_VERNEED, Out<ELFT>::VerNeed});
Add({DT_VERNEEDNUM, NeedNum});
}
if (Config->EMachine == EM_MIPS) {
Add({DT_MIPS_RLD_VERSION, 1});
Add({DT_MIPS_FLAGS, RHF_NOTPOT});
@ -1513,6 +1519,102 @@ SymbolTableSection<ELFT>::getOutputSection(SymbolBody *Sym) {
return nullptr;
}
template <class ELFT>
VersionTableSection<ELFT>::VersionTableSection()
: OutputSectionBase<ELFT>(".gnu.version", SHT_GNU_versym, SHF_ALLOC) {}
template <class ELFT> void VersionTableSection<ELFT>::finalize() {
this->Header.sh_size =
sizeof(Elf_Versym) * (Out<ELFT>::DynSymTab->getSymbols().size() + 1);
this->Header.sh_entsize = sizeof(Elf_Versym);
}
template <class ELFT> void VersionTableSection<ELFT>::writeTo(uint8_t *Buf) {
auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf) + 1;
for (const std::pair<SymbolBody *, size_t> &P :
Out<ELFT>::DynSymTab->getSymbols()) {
if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(P.first))
OutVersym->vs_index = SS->VersionId;
else
// The reserved identifier for a non-versioned global symbol.
OutVersym->vs_index = 1;
++OutVersym;
}
}
template <class ELFT>
VersionNeedSection<ELFT>::VersionNeedSection()
: OutputSectionBase<ELFT>(".gnu.version_r", SHT_GNU_verneed, SHF_ALLOC) {}
template <class ELFT>
void VersionNeedSection<ELFT>::addSymbol(SharedSymbol<ELFT> *SS) {
if (!SS->Verdef) {
// The reserved identifier for a non-versioned global symbol.
SS->VersionId = 1;
return;
}
SharedFile<ELFT> *F = SS->File;
// If we don't already know that we need an Elf_Verneed for this DSO, prepare
// to create one by adding it to our needed list and creating a dynstr entry
// for the soname.
if (F->VerdefMap.empty())
Needed.push_back({F, Out<ELFT>::DynStrTab->addString(F->getSoName())});
typename SharedFile<ELFT>::NeededVer &NV = F->VerdefMap[SS->Verdef];
// If we don't already know that we need an Elf_Vernaux for this Elf_Verdef,
// prepare to create one by allocating a version identifier and creating a
// dynstr entry for the version name.
if (NV.Index == 0) {
NV.StrTab = Out<ELFT>::DynStrTab->addString(
SS->File->getStringTable().data() + SS->Verdef->getAux()->vda_name);
NV.Index = NextIndex++;
}
SS->VersionId = NV.Index;
}
template <class ELFT> void VersionNeedSection<ELFT>::writeTo(uint8_t *Buf) {
// The Elf_Verneeds need to appear first, followed by the Elf_Vernauxs.
auto *Verneed = reinterpret_cast<Elf_Verneed *>(Buf);
auto *Vernaux = reinterpret_cast<Elf_Vernaux *>(Verneed + Needed.size());
for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed) {
// Create an Elf_Verneed for this DSO.
Verneed->vn_version = 1;
Verneed->vn_cnt = P.first->VerdefMap.size();
Verneed->vn_file = P.second;
Verneed->vn_aux =
reinterpret_cast<char *>(Vernaux) - reinterpret_cast<char *>(Verneed);
Verneed->vn_next = sizeof(Elf_Verneed);
++Verneed;
// Create the Elf_Vernauxs for this Elf_Verneed. The loop iterates over
// VerdefMap, which will only contain references to needed version
// definitions. Each Elf_Vernaux is based on the information contained in
// the Elf_Verdef in the source DSO. This loop iterates over a std::map of
// pointers, but is deterministic because the pointers refer to Elf_Verdef
// data structures within a single input file.
for (auto &NV : P.first->VerdefMap) {
Vernaux->vna_hash = NV.first->vd_hash;
Vernaux->vna_flags = 0;
Vernaux->vna_other = NV.second.Index;
Vernaux->vna_name = NV.second.StrTab;
Vernaux->vna_next = sizeof(Elf_Vernaux);
++Vernaux;
}
Vernaux[-1].vna_next = 0;
}
Verneed[-1].vn_next = 0;
}
template <class ELFT> void VersionNeedSection<ELFT>::finalize() {
this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
this->Header.sh_info = Needed.size();
unsigned Size = Needed.size() * sizeof(Elf_Verneed);
for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed)
Size += P.first->VerdefMap.size() * sizeof(Elf_Vernaux);
this->Header.sh_size = Size;
}
template <class ELFT>
BuildIdSection<ELFT>::BuildIdSection(size_t HashSize)
: OutputSectionBase<ELFT>(".note.gnu.build-id", SHT_NOTE, SHF_ALLOC),
@ -1666,6 +1768,16 @@ template class SymbolTableSection<ELF32BE>;
template class SymbolTableSection<ELF64LE>;
template class SymbolTableSection<ELF64BE>;
template class VersionTableSection<ELF32LE>;
template class VersionTableSection<ELF32BE>;
template class VersionTableSection<ELF64LE>;
template class VersionTableSection<ELF64BE>;
template class VersionNeedSection<ELF32LE>;
template class VersionNeedSection<ELF32BE>;
template class VersionNeedSection<ELF64LE>;
template class VersionNeedSection<ELF64BE>;
template class BuildIdSection<ELF32LE>;
template class BuildIdSection<ELF32BE>;
template class BuildIdSection<ELF64LE>;

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@ -33,6 +33,8 @@ template <class ELFT> class MergeInputSection;
template <class ELFT> class MipsReginfoInputSection;
template <class ELFT> class OutputSection;
template <class ELFT> class ObjectFile;
template <class ELFT> class SharedFile;
template <class ELFT> class SharedSymbol;
template <class ELFT> class DefinedRegular;
template <class ELFT>
@ -222,6 +224,49 @@ private:
std::vector<std::pair<SymbolBody *, size_t>> Symbols;
};
// For more information about .gnu.version and .gnu.version_r see:
// https://www.akkadia.org/drepper/symbol-versioning
// The .gnu.version section specifies the required version of each symbol in the
// dynamic symbol table. It contains one Elf_Versym for each dynamic symbol
// table entry. An Elf_Versym is just a 16-bit integer that refers to a version
// identifier defined in the .gnu.version_r section.
template <class ELFT>
class VersionTableSection final : public OutputSectionBase<ELFT> {
typedef typename ELFT::Versym Elf_Versym;
public:
VersionTableSection();
void finalize() override;
void writeTo(uint8_t *Buf) override;
};
// The .gnu.version_r section defines the version identifiers used by
// .gnu.version. It contains a linked list of Elf_Verneed data structures. Each
// Elf_Verneed specifies the version requirements for a single DSO, and contains
// a reference to a linked list of Elf_Vernaux data structures which define the
// mapping from version identifiers to version names.
template <class ELFT>
class VersionNeedSection final : public OutputSectionBase<ELFT> {
typedef typename ELFT::Verneed Elf_Verneed;
typedef typename ELFT::Vernaux Elf_Vernaux;
// A vector of shared files that need Elf_Verneed data structures and the
// string table offsets of their sonames.
std::vector<std::pair<SharedFile<ELFT> *, size_t>> Needed;
// The next available version identifier. Identifiers start at 2 because 0 and
// 1 are reserved.
unsigned NextIndex = 2;
public:
VersionNeedSection();
void addSymbol(SharedSymbol<ELFT> *SS);
void finalize() override;
void writeTo(uint8_t *Buf) override;
size_t getNeedNum() const { return Needed.size(); }
};
template <class ELFT>
class RelocationSection final : public OutputSectionBase<ELFT> {
typedef typename ELFT::Rel Elf_Rel;
@ -562,6 +607,8 @@ template <class ELFT> struct Out {
static StringTableSection<ELFT> *StrTab;
static SymbolTableSection<ELFT> *DynSymTab;
static SymbolTableSection<ELFT> *SymTab;
static VersionTableSection<ELFT> *VerSym;
static VersionNeedSection<ELFT> *VerNeed;
static Elf_Phdr *TlsPhdr;
static OutputSectionBase<ELFT> *ElfHeader;
static OutputSectionBase<ELFT> *ProgramHeaders;
@ -587,6 +634,8 @@ template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::ShStrTab;
template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::StrTab;
template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::DynSymTab;
template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::SymTab;
template <class ELFT> VersionTableSection<ELFT> *Out<ELFT>::VerSym;
template <class ELFT> VersionNeedSection<ELFT> *Out<ELFT>::VerNeed;
template <class ELFT> typename ELFT::Phdr *Out<ELFT>::TlsPhdr;
template <class ELFT> OutputSectionBase<ELFT> *Out<ELFT>::ElfHeader;
template <class ELFT> OutputSectionBase<ELFT> *Out<ELFT>::ProgramHeaders;

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@ -324,6 +324,7 @@ public:
template <class ELFT> class SharedSymbol : public Defined {
typedef typename ELFT::Sym Elf_Sym;
typedef typename ELFT::Verdef Elf_Verdef;
typedef typename ELFT::uint uintX_t;
public:
@ -331,10 +332,11 @@ public:
return S->kind() == SymbolBody::SharedKind;
}
SharedSymbol(SharedFile<ELFT> *F, StringRef Name, const Elf_Sym &Sym)
SharedSymbol(SharedFile<ELFT> *F, StringRef Name, const Elf_Sym &Sym,
const Elf_Verdef *Verdef)
: Defined(SymbolBody::SharedKind, Name, Sym.getBinding(), Sym.st_other,
Sym.getType()),
File(F), Sym(Sym) {
File(F), Sym(Sym), Verdef(Verdef) {
// IFuncs defined in DSOs are treated as functions by the static linker.
if (isGnuIFunc())
Type = llvm::ELF::STT_FUNC;
@ -343,6 +345,14 @@ public:
SharedFile<ELFT> *File;
const Elf_Sym &Sym;
// This field is initially a pointer to the symbol's version definition. As
// symbols are added to the version table, this field is replaced with the
// version identifier to be stored in .gnu.version in the output file.
union {
const Elf_Verdef *Verdef;
uint16_t VersionId;
};
// OffsetInBss is significant only when needsCopy() is true.
uintX_t OffsetInBss = 0;

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@ -132,6 +132,8 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
StringTableSection<ELFT> DynStrTab(".dynstr", true);
StringTableSection<ELFT> ShStrTab(".shstrtab", false);
SymbolTableSection<ELFT> DynSymTab(*Symtab, DynStrTab);
VersionTableSection<ELFT> VerSym;
VersionNeedSection<ELFT> VerNeed;
OutputSectionBase<ELFT> ElfHeader("", 0, SHF_ALLOC);
ElfHeader.setSize(sizeof(Elf_Ehdr));
@ -195,6 +197,8 @@ template <class ELFT> void elf::writeResult(SymbolTable<ELFT> *Symtab) {
Out<ELFT>::ShStrTab = &ShStrTab;
Out<ELFT>::StrTab = StrTab.get();
Out<ELFT>::SymTab = SymTabSec.get();
Out<ELFT>::VerSym = &VerSym;
Out<ELFT>::VerNeed = &VerNeed;
Out<ELFT>::Bss = nullptr;
Out<ELFT>::MipsRldMap = MipsRldMap.get();
Out<ELFT>::Opd = nullptr;
@ -1367,8 +1371,11 @@ template <class ELFT> void Writer<ELFT>::createSections() {
if (Out<ELFT>::SymTab)
Out<ELFT>::SymTab->addSymbol(Body);
if (isOutputDynamic() && S->includeInDynsym())
if (isOutputDynamic() && S->includeInDynsym()) {
Out<ELFT>::DynSymTab->addSymbol(Body);
if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(Body))
Out<ELFT>::VerNeed->addSymbol(SS);
}
}
// Do not proceed if there was an undefined symbol.
@ -1436,6 +1443,10 @@ template <class ELFT> void Writer<ELFT>::addPredefinedSections() {
Add(Out<ELFT>::StrTab);
if (isOutputDynamic()) {
Add(Out<ELFT>::DynSymTab);
if (Out<ELFT>::VerNeed->getNeedNum() != 0) {
Add(Out<ELFT>::VerSym);
Add(Out<ELFT>::VerNeed);
}
Add(Out<ELFT>::GnuHashTab);
Add(Out<ELFT>::HashTab);
Add(Out<ELFT>::Dynamic);

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@ -0,0 +1,58 @@
#!/bin/sh -eu
# This script was used to produce the verneed{1,2}.so files.
tmp=$(mktemp -d)
echo "v1 {}; v2 {}; v3 {}; { local: *; };" > $tmp/verneed.script
cat > $tmp/verneed1.s <<eof
.globl f1_v1
f1_v1:
ret
.globl f1_v2
f1_v2:
ret
.globl f1_v3
f1_v3:
ret
.symver f1_v1, f1@v1
.symver f1_v2, f1@v2
.symver f1_v3, f1@@v3
.globl f2_v1
f2_v1:
ret
.globl f2_v2
f2_v2:
ret
.symver f2_v1, f2@v1
.symver f2_v2, f2@@v2
.globl f3_v1
f3_v1:
ret
.symver f3_v1, f3@v1
eof
as -o $tmp/verneed1.o $tmp/verneed1.s
ld.gold -shared -o verneed1.so $tmp/verneed1.o --version-script $tmp/verneed.script -soname verneed1.so.0
cat > $tmp/verneed2.s <<eof
.globl g1_v1
g1_v1:
ret
.symver g1_v1, g1@@v1
eof
as -o $tmp/verneed2.o $tmp/verneed2.s
ld.gold -shared -o verneed2.so $tmp/verneed2.o --version-script $tmp/verneed.script -soname verneed2.so.0
rm -rf $tmp

BIN
lld/test/ELF/Inputs/verneed1.so Executable file

Binary file not shown.

BIN
lld/test/ELF/Inputs/verneed2.so Executable file

Binary file not shown.

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@ -0,0 +1,8 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
# RUN: not ld.lld %t.o %S/Inputs/verneed1.so -o %t 2>&1 | FileCheck %s
# CHECK: undefined symbol: f3 in
.globl _start
_start:
call f3

104
lld/test/ELF/verneed.s Normal file
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@ -0,0 +1,104 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
# RUN: ld.lld %t.o %S/Inputs/verneed1.so %S/Inputs/verneed2.so -o %t
# RUN: llvm-readobj -sections -dyn-symbols -dynamic-table %t | FileCheck %s
# RUN: llvm-objdump -s %t | FileCheck --check-prefix=CONTENTS %s
# CHECK: Index: 2
# CHECK-NEXT: Name: .gnu.version (9)
# CHECK-NEXT: Type: SHT_GNU_versym (0x6FFFFFFF)
# CHECK-NEXT: Flags [ (0x2)
# CHECK-NEXT: SHF_ALLOC (0x2)
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x10228
# CHECK-NEXT: Offset: 0x228
# CHECK-NEXT: Size: 8
# CHECK-NEXT: Link: 0
# CHECK-NEXT: Info: 0
# CHECK-NEXT: AddressAlignment: 0
# CHECK-NEXT: EntrySize: 2
# CHECK-NEXT: }
# CHECK-NEXT: Section {
# CHECK-NEXT: Index: 3
# CHECK-NEXT: Name: .gnu.version_r (22)
# CHECK-NEXT: Type: SHT_GNU_verneed (0x6FFFFFFE)
# CHECK-NEXT: Flags [ (0x2)
# CHECK-NEXT: SHF_ALLOC (0x2)
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x10230
# CHECK-NEXT: Offset: 0x230
# CHECK-NEXT: Size: 80
# CHECK-NEXT: Link: 5
# CHECK-NEXT: Info: 2
# CHECK-NEXT: AddressAlignment: 0
# CHECK-NEXT: EntrySize: 0
# CHECK-NEXT: }
# CHECK: DynamicSymbols [
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: @ (0)
# CHECK-NEXT: Value: 0x0
# CHECK-NEXT: Size: 0
# CHECK-NEXT: Binding: Local (0x0)
# CHECK-NEXT: Type: None (0x0)
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: Undefined (0x0)
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: f1@v3 (1)
# CHECK-NEXT: Value: 0x0
# CHECK-NEXT: Size: 0
# CHECK-NEXT: Binding: Global (0x1)
# CHECK-NEXT: Type: None (0x0)
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: Undefined (0x0)
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: f2@v2 (21)
# CHECK-NEXT: Value: 0x0
# CHECK-NEXT: Size: 0
# CHECK-NEXT: Binding: Global (0x1)
# CHECK-NEXT: Type: None (0x0)
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: Undefined (0x0)
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: g1@v1 (27)
# CHECK-NEXT: Value: 0x0
# CHECK-NEXT: Size: 0
# CHECK-NEXT: Binding: Global (0x1)
# CHECK-NEXT: Type: None (0x0)
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: Undefined (0x0)
# CHECK-NEXT: }
# CHECK-NEXT: ]
# CHECK: 0x000000006FFFFFF0 VERSYM 0x10228
# CHECK-NEXT: 0x000000006FFFFFFE VERNEED 0x10230
# CHECK-NEXT: 0x000000006FFFFFFF VERNEEDNUM 2
# CONTENTS: Contents of section .gnu.version:
# CONTENTS-NEXT: 10228 00000200 03000400
# CONTENTS-NEXT: Contents of section .gnu.version_r:
# vn_version
# vn_cnt
# vn_file vn_aux vn_next
# CONTENTS-NEXT: 10230 01000200 04000000 20000000 10000000 ........ .......
# CONTENTS-NEXT: 10240 01000100 1e000000 30000000 00000000 ........0.......
# vna_hash vna_flags
# vna_other
# vna_name
# vna_next
# CONTENTS-NEXT: 10250 92070000 00000300 18000000 10000000 ................
# CONTENTS-NEXT: 10260 93070000 00000200 12000000 00000000 ................
# CONTENTS-NEXT: 10270 91070000 00000400 2c000000 00000000 ........,.......
# CONTENTS: Contents of section .dynstr:
# CONTENTS-NEXT: 102a8 00663100 7665726e 65656431 2e736f2e .f1.verneed1.so.
# CONTENTS-NEXT: 102b8 30007633 00663200 76320067 31007665 0.v3.f2.v2.g1.ve
# CONTENTS-NEXT: 102c8 726e6565 64322e73 6f2e3000 763100 rneed2.so.0.v1.
.globl _start
_start:
call f1
call f2
call g1