Index: ELF/CMakeLists.txt =================================================================== --- ELF/CMakeLists.txt +++ ELF/CMakeLists.txt @@ -5,7 +5,6 @@ add_lld_library(lldELF Driver.cpp DriverUtils.cpp - DynamicList.cpp Error.cpp ICF.cpp InputFiles.cpp @@ -15,6 +14,7 @@ MarkLive.cpp OutputSections.cpp ScriptParser.cpp + SymbolListFile.cpp SymbolTable.cpp Symbols.cpp Target.cpp Index: ELF/Config.h =================================================================== --- ELF/Config.h +++ ELF/Config.h @@ -12,6 +12,7 @@ #include "llvm/ADT/MapVector.h" #include "llvm/ADT/StringRef.h" +#include "llvm/ADT/StringSet.h" #include "llvm/Support/ELF.h" #include @@ -51,6 +52,7 @@ std::vector DynamicList; std::vector SearchPaths; std::vector Undefined; + std::vector VersionScriptGlobals; bool AllowMultipleDefinition; bool AsNeeded = false; bool Bsymbolic; @@ -85,6 +87,7 @@ bool Threads; bool Trace; bool Verbose; + bool VersionScript; bool WarnCommon; bool ZExecStack; bool ZNodelete; Index: ELF/Driver.h =================================================================== --- ELF/Driver.h +++ ELF/Driver.h @@ -33,6 +33,7 @@ llvm::Optional readFile(StringRef Path); void readConfigs(llvm::opt::InputArgList &Args); void readDynamicList(StringRef Path); + void readVersionScript(StringRef Path); void createFiles(llvm::opt::InputArgList &Args); template void link(llvm::opt::InputArgList &Args); Index: ELF/Driver.cpp =================================================================== --- ELF/Driver.cpp +++ ELF/Driver.cpp @@ -9,11 +9,11 @@ #include "Driver.h" #include "Config.h" -#include "DynamicList.h" #include "Error.h" #include "ICF.h" #include "InputFiles.h" #include "LinkerScript.h" +#include "SymbolListFile.h" #include "SymbolTable.h" #include "Target.h" #include "Writer.h" @@ -151,6 +151,11 @@ parseDynamicList(*Buffer); } +void LinkerDriver::readVersionScript(StringRef Path) { + if (Optional Buffer = readFile(Path)) + parseVersionScript(*Buffer); +} + // Add a given library by searching it from input search paths. void LinkerDriver::addLibrary(StringRef Name) { std::string Path = searchLibrary(Name); @@ -376,6 +381,10 @@ for (auto *Arg : Args.filtered(OPT_export_dynamic_symbol)) Config->DynamicList.push_back(Arg->getValue()); + + Config->VersionScript = Args.hasArg(OPT_version_script); + if (Config->VersionScript) + readVersionScript(getString(Args, OPT_version_script)); } void LinkerDriver::createFiles(opt::InputArgList &Args) { @@ -460,6 +469,7 @@ Symtab.scanShlibUndefined(); Symtab.scanDynamicList(); + Symtab.scanVersionScript(); Symtab.addCombinedLtoObject(); Index: ELF/Options.td =================================================================== --- ELF/Options.td +++ ELF/Options.td @@ -160,6 +160,9 @@ def version : Flag<["--", "-"], "version">, HelpText<"Display the version number">; +def version_script : Separate<["--", "-"], "version-script">, + HelpText<"Read a version script">; + def warn_common : Flag<["--", "-"], "warn-common">, HelpText<"Warn about duplicate common symbols">; @@ -234,7 +237,6 @@ def no_warn_mismatch : Flag<["--"], "no-warn-mismatch">; def rpath_link : Separate<["--", "-"], "rpath-link">; def rpath_link_eq : Joined<["--", "-"], "rpath-link=">; -def version_script : Separate<["--"], "version-script">; def warn_execstack : Flag<["--"], "warn-execstack">; def warn_shared_textrel : Flag<["--"], "warn-shared-textrel">; def G : Separate<["-"], "G">; Index: ELF/SymbolListFile.h =================================================================== --- ELF/SymbolListFile.h +++ ELF/SymbolListFile.h @@ -1,4 +1,4 @@ -//===- DynamicList.h --------------------------------------------*- C++ -*-===// +//===- SymbolListFile.h -----------------------------------------*- C++ -*-===// // // The LLVM Linker // @@ -7,8 +7,8 @@ // //===----------------------------------------------------------------------===// -#ifndef LLD_ELF_DYNAMIC_LIST_H -#define LLD_ELF_DYNAMIC_LIST_H +#ifndef LLD_ELF_SYMBOL_LIST_FILE_H +#define LLD_ELF_SYMBOL_LIST_FILE_H #include "lld/Core/LLVM.h" #include "llvm/Support/MemoryBuffer.h" @@ -17,6 +17,7 @@ namespace elf { void parseDynamicList(MemoryBufferRef MB); +void parseVersionScript(MemoryBufferRef MB); } // namespace elf } // namespace lld Index: ELF/SymbolListFile.cpp =================================================================== --- ELF/SymbolListFile.cpp +++ ELF/SymbolListFile.cpp @@ -1,4 +1,4 @@ -//===- LinkerScript.cpp ---------------------------------------------------===// +//===- SymbolListFile.cpp -------------------------------------------------===// // // The LLVM Linker // @@ -13,7 +13,7 @@ // //===----------------------------------------------------------------------===// -#include "DynamicList.h" +#include "SymbolListFile.h" #include "Config.h" #include "ScriptParser.h" #include "llvm/Support/MemoryBuffer.h" @@ -62,3 +62,45 @@ void elf::parseDynamicList(MemoryBufferRef MB) { DynamicListParser(MB.getBuffer()).run(); } + +// Parse the --version-script argument. We currently only accept the following +// version script syntax: +// +// { [ global: symbol1; symbol2; [...]; symbolN; ] local: *; }; +// +// No wildcards are supported, other than for the local entry. Symbol versioning +// is also not supported. + +class VersionScriptParser final : public ScriptParserBase { +public: + VersionScriptParser(StringRef S) : ScriptParserBase(S) {} + + void run() override; +}; + +void VersionScriptParser::run() { + expect("{"); + if (peek() == "global:") { + next(); + while (!Error) { + Config->VersionScriptGlobals.push_back(next()); + expect(";"); + if (peek() == "local:") { + next(); + break; + } + } + } else { + expect("local:"); + } + expect("*"); + expect(";"); + expect("}"); + expect(";"); + if (!atEOF()) + setError("expected EOF"); +} + +void elf::parseVersionScript(MemoryBufferRef MB) { + VersionScriptParser(MB.getBuffer()).run(); +} Index: ELF/SymbolTable.h =================================================================== --- ELF/SymbolTable.h +++ ELF/SymbolTable.h @@ -61,6 +61,7 @@ void scanShlibUndefined(); void scanDynamicList(); + void scanVersionScript(); SymbolBody *find(StringRef Name); void wrap(StringRef Name); InputFile *findFile(SymbolBody *B); Index: ELF/SymbolTable.cpp =================================================================== --- ELF/SymbolTable.cpp +++ ELF/SymbolTable.cpp @@ -290,7 +290,12 @@ auto P = Symtab.insert(std::make_pair(Name, NumSyms)); Symbol *Sym; if (P.second) { - Sym = new (Alloc) Symbol{New, STV_DEFAULT, false, false}; + Sym = new (Alloc) Symbol; + Sym->Body = New; + Sym->Visibility = STV_DEFAULT; + Sym->IsUsedInRegularObj = false; + Sym->ExportDynamic = false; + Sym->VersionScriptGlobal = !Config->VersionScript; SymVector.push_back(Sym); } else { Sym = SymVector[P.first->second]; @@ -375,6 +380,15 @@ B->Backref->ExportDynamic = true; } +// This function processes the --version-script option by marking all global +// symbols with the VersionScriptGlobal flag, which acts as a filter on the +// dynamic symbol table. +template void SymbolTable::scanVersionScript() { + for (StringRef S : Config->VersionScriptGlobals) + if (SymbolBody *B = find(S)) + B->Backref->VersionScriptGlobal = true; +} + template class elf::SymbolTable; template class elf::SymbolTable; template class elf::SymbolTable; Index: ELF/Symbols.h =================================================================== --- ELF/Symbols.h +++ ELF/Symbols.h @@ -60,6 +60,11 @@ // --export-dynamic, and by dynamic lists. unsigned ExportDynamic : 1; + // This flag acts as an additional filter on the dynamic symbol list. It is + // set if there is no version script, or if the symbol appears in the global + // section of the version script. + unsigned VersionScriptGlobal : 1; + bool includeInDynsym() const; }; Index: ELF/Symbols.cpp =================================================================== --- ELF/Symbols.cpp +++ ELF/Symbols.cpp @@ -115,31 +115,26 @@ if (isLocal()) return false; + // Shared symbols resolve to the definition in the DSO. if (isShared()) return true; - if (Backref->Visibility != STV_DEFAULT) + // That's all that can be preempted in a non-DSO. + if (!Config->Shared) return false; - if (isUndefined()) { - if (!isWeak()) - return true; - - // Ideally the static linker should see a definition for every symbol, but - // shared object are normally allowed to have undefined references that the - // static linker never sees a definition for. - if (Config->Shared) - return true; - - // Otherwise, just resolve to 0. - return false; - } + // Undefined symbols in DSOs can only be preempted if they are strong. + // Weak symbols just resolve to zero. + if (isUndefined()) + return !isWeak(); - if (!Config->Shared) - return false; + // -Bsymbolic means that not even default visibility symbols can be preempted. if (Config->Bsymbolic || (Config->BsymbolicFunctions && isFunc())) return false; - return true; + + // Only default visibility symbols that appear in the dynamic symbol table can + // be preempted. + return Backref->Visibility == STV_DEFAULT && Backref->includeInDynsym(); } template @@ -324,7 +319,7 @@ bool Symbol::includeInDynsym() const { if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED) return false; - return ExportDynamic || Body->isShared(); + return (ExportDynamic && VersionScriptGlobal) || Body->isShared(); } template uint32_t SymbolBody::template getVA(uint32_t) const; Index: test/ELF/lto/internalize-version-script.ll =================================================================== --- /dev/null +++ test/ELF/lto/internalize-version-script.ll @@ -0,0 +1,22 @@ +; REQUIRES: x86 +; RUN: llvm-as %s -o %t.o +; RUN: echo "{ global: foo; local: *; };" > %t.script +; RUN: ld.lld -m elf_x86_64 %t.o -o %t2 -shared --version-script %t.script -save-temps +; RUN: llvm-dis < %t2.lto.bc | FileCheck %s + +target triple = "x86_64-unknown-linux-gnu" +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" + +define void @foo() { + ret void +} + +define void @bar() { + ret void +} + +; Check that foo is not internalized. +; CHECK: define void @foo() + +; Check that bar is correctly internalized. +; CHECK: define internal void @bar() Index: test/ELF/no-inhibit-exec.s =================================================================== --- test/ELF/no-inhibit-exec.s +++ test/ELF/no-inhibit-exec.s @@ -6,7 +6,7 @@ # CHECK: Disassembly of section .text: # CHECK-NEXT: _start -# CHECK-NEXT: 11000: e8 00 00 00 00 callq 0 +# CHECK-NEXT: 11000: e8 fb ef fe ff callq -69637 # next code will not link without noinhibit-exec flag # because of undefined symbol _bar Index: test/ELF/version-script.s =================================================================== --- /dev/null +++ test/ELF/version-script.s @@ -0,0 +1,126 @@ +# REQUIRES: x86 + +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/shared.s -o %t2.o +# RUN: ld.lld -shared %t2.o -soname shared -o %t2.so + +# RUN: echo "{ global: foo1; foo3; local: *; };" > %t.script +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o +# RUN: ld.lld --version-script %t.script -shared %t.o %t2.so -o %t.so +# RUN: llvm-readobj -dyn-symbols %t.so | FileCheck --check-prefix=DSO %s + +# RUN: echo "{ local: *; };" > %t3.script +# RUN: ld.lld --version-script %t3.script -shared %t.o %t2.so -o %t3.so +# RUN: llvm-readobj -dyn-symbols %t3.so | FileCheck --check-prefix=DSO2 %s + +# --version-script filters --dynamic-list. +# RUN: echo "{ foo1; foo2; };" > %t.list +# RUN: ld.lld --version-script %t.script --dynamic-list %t.list %t.o %t2.so -o %t +# RUN: llvm-readobj -dyn-symbols %t | FileCheck --check-prefix=EXE %s + +# DSO: DynamicSymbols [ +# DSO-NEXT: Symbol { +# DSO-NEXT: Name: @ (0) +# DSO-NEXT: Value: 0x0 +# DSO-NEXT: Size: 0 +# DSO-NEXT: Binding: Local (0x0) +# DSO-NEXT: Type: None (0x0) +# DSO-NEXT: Other: 0 +# DSO-NEXT: Section: Undefined (0x0) +# DSO-NEXT: } +# DSO-NEXT: Symbol { +# DSO-NEXT: Name: bar@ (1) +# DSO-NEXT: Value: 0x0 +# DSO-NEXT: Size: 0 +# DSO-NEXT: Binding: Global (0x1) +# DSO-NEXT: Type: Function (0x2) +# DSO-NEXT: Other: 0 +# DSO-NEXT: Section: Undefined (0x0) +# DSO-NEXT: } +# DSO-NEXT: Symbol { +# DSO-NEXT: Name: foo1@ (5) +# DSO-NEXT: Value: 0x1000 +# DSO-NEXT: Size: 0 +# DSO-NEXT: Binding: Global (0x1) +# DSO-NEXT: Type: None (0x0) +# DSO-NEXT: Other: 0 +# DSO-NEXT: Section: .text (0x5) +# DSO-NEXT: } +# DSO-NEXT: Symbol { +# DSO-NEXT: Name: foo3@ (10) +# DSO-NEXT: Value: 0x1007 +# DSO-NEXT: Size: 0 +# DSO-NEXT: Binding: Global (0x1) +# DSO-NEXT: Type: None (0x0) +# DSO-NEXT: Other: 0 +# DSO-NEXT: Section: .text (0x5) +# DSO-NEXT: } +# DSO-NEXT: ] + +# DSO2: DynamicSymbols [ +# DSO2-NEXT: Symbol { +# DSO2-NEXT: Name: @ (0) +# DSO2-NEXT: Value: 0x0 +# DSO2-NEXT: Size: 0 +# DSO2-NEXT: Binding: Local (0x0) +# DSO2-NEXT: Type: None (0x0) +# DSO2-NEXT: Other: 0 +# DSO2-NEXT: Section: Undefined (0x0) +# DSO2-NEXT: } +# DSO2-NEXT: Symbol { +# DSO2-NEXT: Name: bar@ (1) +# DSO2-NEXT: Value: 0x0 +# DSO2-NEXT: Size: 0 +# DSO2-NEXT: Binding: Global (0x1) +# DSO2-NEXT: Type: Function (0x2) +# DSO2-NEXT: Other: 0 +# DSO2-NEXT: Section: Undefined (0x0) +# DSO2-NEXT: } +# DSO2-NEXT: ] + +# EXE: DynamicSymbols [ +# EXE-NEXT: Symbol { +# EXE-NEXT: Name: @ (0) +# EXE-NEXT: Value: 0x0 +# EXE-NEXT: Size: 0 +# EXE-NEXT: Binding: Local (0x0) +# EXE-NEXT: Type: None (0x0) +# EXE-NEXT: Other: 0 +# EXE-NEXT: Section: Undefined (0x0) +# EXE-NEXT: } +# EXE-NEXT: Symbol { +# EXE-NEXT: Name: bar@ (1) +# EXE-NEXT: Value: 0x0 +# EXE-NEXT: Size: 0 +# EXE-NEXT: Binding: Global (0x1) +# EXE-NEXT: Type: Function (0x2) +# EXE-NEXT: Other: 0 +# EXE-NEXT: Section: Undefined (0x0) +# EXE-NEXT: } +# EXE-NEXT: Symbol { +# EXE-NEXT: Name: foo1@ (5) +# EXE-NEXT: Value: 0x11000 +# EXE-NEXT: Size: 0 +# EXE-NEXT: Binding: Global (0x1) +# EXE-NEXT: Type: None (0x0) +# EXE-NEXT: Other: 0 +# EXE-NEXT: Section: .text (0x5) +# EXE-NEXT: } +# EXE-NEXT: ] + +.globl foo1 +foo1: + call bar@PLT + ret + +.globl foo2 +foo2: + ret + +.globl foo3 +foo3: + call foo2@PLT + ret + +.globl _start +_start: + ret