From 5c36e5938dbb2d4c135819189fd68fdb5982850c Mon Sep 17 00:00:00 2001 From: George Rimar Date: Tue, 2 Feb 2016 09:28:53 +0000 Subject: [PATCH] [ELF] Implemented -Bsymbolic-functions command line option -Bsymbolic-functions: When creating a shared library, bind references to global function symbols to the definition within the shared library, if any. This patch also fixed behavior of already existent -Bsymbolic: previously PLT entries were created even if -Bsymbolic was specified. Differential revision: http://reviews.llvm.org/D16411 llvm-svn: 259481 --- lld/ELF/Config.h | 1 + lld/ELF/Driver.cpp | 1 + lld/ELF/Options.td | 3 +++ lld/ELF/OutputSections.cpp | 6 +++++- lld/ELF/Symbols.cpp | 13 ++++++++----- lld/ELF/Symbols.h | 15 ++++++++++----- lld/test/ELF/bsymbolic.s | 30 ++++++++++++++++++++++++++++++ 7 files changed, 58 insertions(+), 11 deletions(-) create mode 100644 lld/test/ELF/bsymbolic.s diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h index 0b92dba..e9113ac 100644 --- a/lld/ELF/Config.h +++ b/lld/ELF/Config.h @@ -53,6 +53,7 @@ struct Configuration { bool AllowMultipleDefinition; bool AsNeeded = false; bool Bsymbolic; + bool BsymbolicFunctions; bool Demangle = true; bool DiscardAll; bool DiscardLocals; diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp index 4fbf202..677d40b 100644 --- a/lld/ELF/Driver.cpp +++ b/lld/ELF/Driver.cpp @@ -188,6 +188,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) { Config->AllowMultipleDefinition = Args.hasArg(OPT_allow_multiple_definition); Config->Bsymbolic = Args.hasArg(OPT_Bsymbolic); + Config->BsymbolicFunctions = Args.hasArg(OPT_Bsymbolic_functions); Config->Demangle = !Args.hasArg(OPT_no_demangle); Config->DiscardAll = Args.hasArg(OPT_discard_all); Config->DiscardLocals = Args.hasArg(OPT_discard_locals); diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td index 0d64989..40bab6a 100644 --- a/lld/ELF/Options.td +++ b/lld/ELF/Options.td @@ -3,6 +3,9 @@ include "llvm/Option/OptParser.td" def Bsymbolic: Flag<["-"], "Bsymbolic">, HelpText<"Bind defined symbols locally">; +def Bsymbolic_functions: Flag<["-"], "Bsymbolic-functions">, + HelpText<"Bind defined function symbols locally">; + def Bdynamic: Flag<["-"], "Bdynamic">, HelpText<"Link against shared libraries">; diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp index 68992bd..d8ec21c 100644 --- a/lld/ELF/OutputSections.cpp +++ b/lld/ELF/OutputSections.cpp @@ -895,7 +895,11 @@ bool elf2::canBePreempted(const SymbolBody *Body, bool NeedsGot) { } if (!Config->Shared) return false; - return Body->getVisibility() == STV_DEFAULT; + if (Body->getVisibility() != STV_DEFAULT) + return false; + if (Config->Bsymbolic || (Config->BsymbolicFunctions && Body->isFunc())) + return false; + return true; } template void OutputSection::writeTo(uint8_t *Buf) { diff --git a/lld/ELF/Symbols.cpp b/lld/ELF/Symbols.cpp index c8b8891..30b086f 100644 --- a/lld/ELF/Symbols.cpp +++ b/lld/ELF/Symbols.cpp @@ -146,12 +146,13 @@ template int SymbolBody::compare(SymbolBody *Other) { } Defined::Defined(Kind K, StringRef Name, bool IsWeak, uint8_t Visibility, - bool IsTls) - : SymbolBody(K, Name, IsWeak, Visibility, IsTls) {} + bool IsTls, bool IsFunction) + : SymbolBody(K, Name, IsWeak, Visibility, IsTls, IsFunction) {} Undefined::Undefined(SymbolBody::Kind K, StringRef N, bool IsWeak, uint8_t Visibility, bool IsTls) - : SymbolBody(K, N, IsWeak, Visibility, IsTls), CanKeepUndefined(false) {} + : SymbolBody(K, N, IsWeak, Visibility, IsTls, /*IsFunction*/ false), + CanKeepUndefined(false) {} Undefined::Undefined(StringRef N, bool IsWeak, uint8_t Visibility, bool CanKeepUndefined) @@ -170,12 +171,14 @@ UndefinedElf::UndefinedElf(StringRef N, const Elf_Sym &Sym) template DefinedSynthetic::DefinedSynthetic(StringRef N, uintX_t Value, OutputSectionBase &Section) - : Defined(SymbolBody::DefinedSyntheticKind, N, false, STV_DEFAULT, false), + : Defined(SymbolBody::DefinedSyntheticKind, N, false, STV_DEFAULT, + /*IsTls*/ false, /*IsFunction*/ false), Value(Value), Section(Section) {} DefinedCommon::DefinedCommon(StringRef N, uint64_t Size, uint64_t Alignment, bool IsWeak, uint8_t Visibility) - : Defined(SymbolBody::DefinedCommonKind, N, IsWeak, Visibility, false) { + : Defined(SymbolBody::DefinedCommonKind, N, IsWeak, Visibility, + /*IsTls*/ false, /*IsFunction*/ false) { MaxAlignment = Alignment; this->Size = Size; } diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h index 67cbaa3..af16124 100644 --- a/lld/ELF/Symbols.h +++ b/lld/ELF/Symbols.h @@ -86,6 +86,7 @@ public: bool isUsedInDynamicReloc() const { return IsUsedInDynamicReloc; } void setUsedInDynamicReloc() { IsUsedInDynamicReloc = true; } bool isTls() const { return IsTls; } + bool isFunc() const { return IsFunc; } // Returns the symbol name. StringRef getName() const { return Name; } @@ -127,9 +128,9 @@ public: protected: SymbolBody(Kind K, StringRef Name, bool IsWeak, uint8_t Visibility, - bool IsTls) + bool IsTls, bool IsFunc) : SymbolKind(K), IsWeak(IsWeak), Visibility(Visibility), IsTls(IsTls), - Name(Name) { + IsFunc(IsFunc), Name(Name) { IsUsedInRegularObj = K != SharedKind && K != LazyKind; IsUsedInDynamicReloc = 0; } @@ -148,6 +149,7 @@ protected: unsigned IsUsedInDynamicReloc : 1; unsigned IsTls : 1; + unsigned IsFunc : 1; StringRef Name; Symbol *Backref = nullptr; }; @@ -155,7 +157,8 @@ protected: // The base class for any defined symbols. class Defined : public SymbolBody { public: - Defined(Kind K, StringRef Name, bool IsWeak, uint8_t Visibility, bool IsTls); + Defined(Kind K, StringRef Name, bool IsWeak, uint8_t Visibility, bool IsTls, + bool IsFunction); static bool classof(const SymbolBody *S) { return S->isDefined(); } }; @@ -167,7 +170,8 @@ protected: public: DefinedElf(Kind K, StringRef N, const Elf_Sym &Sym) : Defined(K, N, Sym.getBinding() == llvm::ELF::STB_WEAK, - Sym.getVisibility(), Sym.getType() == llvm::ELF::STT_TLS), + Sym.getVisibility(), Sym.getType() == llvm::ELF::STT_TLS, + Sym.getType() == llvm::ELF::STT_FUNC), Sym(Sym) {} const Elf_Sym &Sym; @@ -289,7 +293,8 @@ public: class Lazy : public SymbolBody { public: Lazy(ArchiveFile *F, const llvm::object::Archive::Symbol S) - : SymbolBody(LazyKind, S.getName(), false, llvm::ELF::STV_DEFAULT, false), + : SymbolBody(LazyKind, S.getName(), false, llvm::ELF::STV_DEFAULT, + /*IsTls*/ false, /*IsFunction*/ false), File(F), Sym(S) {} static bool classof(const SymbolBody *S) { return S->kind() == LazyKind; } diff --git a/lld/test/ELF/bsymbolic.s b/lld/test/ELF/bsymbolic.s new file mode 100644 index 0000000..3929d7b --- /dev/null +++ b/lld/test/ELF/bsymbolic.s @@ -0,0 +1,30 @@ +// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o +// RUN: ld.lld -shared %t.o -o %t0.so +// RUN: ld.lld -shared -Bsymbolic %t.o -o %t1.so +// RUN: ld.lld -shared -Bsymbolic-functions %t.o -o %t2.so +// RUN: llvm-readobj -s %t0.so | FileCheck -check-prefix=NOOPTION %s +// RUN: llvm-readobj -s %t1.so | FileCheck -check-prefix=SYMBOLIC %s +// RUN: llvm-readobj -s %t2.so | FileCheck -check-prefix=SYMBOLIC %s + +// NOOPTION: Section { +// NOOPTION: Name: .plt + +// SYMBOLIC: Section { +// SYMBOLIC-NOT: Name: .plt + +.text +.globl foo +.type foo,@function +foo: +nop + +.globl bar +.type bar,@function +bar: +nop + +.globl do +.type do,@function +do: +callq foo@PLT +callq bar@PLT -- 2.7.4