diff options
Diffstat (limited to 'ELF/Relocations.cpp')
| -rw-r--r-- | ELF/Relocations.cpp | 1663 |
1 files changed, 985 insertions, 678 deletions
diff --git a/ELF/Relocations.cpp b/ELF/Relocations.cpp index 812468896f0d..ee48f4808136 100644 --- a/ELF/Relocations.cpp +++ b/ELF/Relocations.cpp @@ -1,9 +1,8 @@ //===- Relocations.cpp ----------------------------------------------------===// // -// The LLVM Linker -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // @@ -66,11 +65,11 @@ using namespace llvm::support::endian; using namespace lld; using namespace lld::elf; -static Optional<std::string> getLinkerScriptLocation(const Symbol &Sym) { - for (BaseCommand *Base : Script->SectionCommands) - if (auto *Cmd = dyn_cast<SymbolAssignment>(Base)) - if (Cmd->Sym == &Sym) - return Cmd->Location; +static Optional<std::string> getLinkerScriptLocation(const Symbol &sym) { + for (BaseCommand *base : script->sectionCommands) + if (auto *cmd = dyn_cast<SymbolAssignment>(base)) + if (cmd->sym == &sym) + return cmd->location; return None; } @@ -79,19 +78,51 @@ static Optional<std::string> getLinkerScriptLocation(const Symbol &Sym) { // >>> defined in /home/alice/src/foo.o // >>> referenced by bar.c:12 (/home/alice/src/bar.c:12) // >>> /home/alice/src/bar.o:(.text+0x1) -static std::string getLocation(InputSectionBase &S, const Symbol &Sym, - uint64_t Off) { - std::string Msg = "\n>>> defined in "; - if (Sym.File) - Msg += toString(Sym.File); - else if (Optional<std::string> Loc = getLinkerScriptLocation(Sym)) - Msg += *Loc; - - Msg += "\n>>> referenced by "; - std::string Src = S.getSrcMsg(Sym, Off); - if (!Src.empty()) - Msg += Src + "\n>>> "; - return Msg + S.getObjMsg(Off); +static std::string getLocation(InputSectionBase &s, const Symbol &sym, + uint64_t off) { + std::string msg = "\n>>> defined in "; + if (sym.file) + msg += toString(sym.file); + else if (Optional<std::string> loc = getLinkerScriptLocation(sym)) + msg += *loc; + + msg += "\n>>> referenced by "; + std::string src = s.getSrcMsg(sym, off); + if (!src.empty()) + msg += src + "\n>>> "; + return msg + s.getObjMsg(off); +} + +namespace { +// Build a bitmask with one bit set for each RelExpr. +// +// Constexpr function arguments can't be used in static asserts, so we +// use template arguments to build the mask. +// But function template partial specializations don't exist (needed +// for base case of the recursion), so we need a dummy struct. +template <RelExpr... Exprs> struct RelExprMaskBuilder { + static inline uint64_t build() { return 0; } +}; + +// Specialization for recursive case. +template <RelExpr Head, RelExpr... Tail> +struct RelExprMaskBuilder<Head, Tail...> { + static inline uint64_t build() { + static_assert(0 <= Head && Head < 64, + "RelExpr is too large for 64-bit mask!"); + return (uint64_t(1) << Head) | RelExprMaskBuilder<Tail...>::build(); + } +}; +} // namespace + +// Return true if `Expr` is one of `Exprs`. +// There are fewer than 64 RelExpr's, so we can represent any set of +// RelExpr's as a constant bit mask and test for membership with a +// couple cheap bitwise operations. +template <RelExpr... Exprs> bool oneof(RelExpr expr) { + assert(0 <= expr && (int)expr < 64 && + "RelExpr is too large for 64-bit mask!"); + return (uint64_t(1) << expr) & RelExprMaskBuilder<Exprs...>::build(); } // This function is similar to the `handleTlsRelocation`. MIPS does not @@ -100,204 +131,173 @@ static std::string getLocation(InputSectionBase &S, const Symbol &Sym, // pollute other `handleTlsRelocation` by MIPS `ifs` statements. // Mips has a custom MipsGotSection that handles the writing of GOT entries // without dynamic relocations. -static unsigned handleMipsTlsRelocation(RelType Type, Symbol &Sym, - InputSectionBase &C, uint64_t Offset, - int64_t Addend, RelExpr Expr) { - if (Expr == R_MIPS_TLSLD) { - In.MipsGot->addTlsIndex(*C.File); - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); +static unsigned handleMipsTlsRelocation(RelType type, Symbol &sym, + InputSectionBase &c, uint64_t offset, + int64_t addend, RelExpr expr) { + if (expr == R_MIPS_TLSLD) { + in.mipsGot->addTlsIndex(*c.file); + c.relocations.push_back({expr, type, offset, addend, &sym}); return 1; } - if (Expr == R_MIPS_TLSGD) { - In.MipsGot->addDynTlsEntry(*C.File, Sym); - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); + if (expr == R_MIPS_TLSGD) { + in.mipsGot->addDynTlsEntry(*c.file, sym); + c.relocations.push_back({expr, type, offset, addend, &sym}); return 1; } return 0; } -// This function is similar to the `handleMipsTlsRelocation`. ARM also does not -// support any relaxations for TLS relocations. ARM is logically similar to Mips -// in how it handles TLS, but Mips uses its own custom GOT which handles some -// of the cases that ARM uses GOT relocations for. -// -// We look for TLS global dynamic and local dynamic relocations, these may -// require the generation of a pair of GOT entries that have associated -// dynamic relocations. When the results of the dynamic relocations can be -// resolved at static link time we do so. This is necessary for static linking -// as there will be no dynamic loader to resolve them at load-time. +// Notes about General Dynamic and Local Dynamic TLS models below. They may +// require the generation of a pair of GOT entries that have associated dynamic +// relocations. The pair of GOT entries created are of the form GOT[e0] Module +// Index (Used to find pointer to TLS block at run-time) GOT[e1] Offset of +// symbol in TLS block. // -// The pair of GOT entries created are of the form -// GOT[e0] Module Index (Used to find pointer to TLS block at run-time) -// GOT[e1] Offset of symbol in TLS block -template <class ELFT> -static unsigned handleARMTlsRelocation(RelType Type, Symbol &Sym, - InputSectionBase &C, uint64_t Offset, - int64_t Addend, RelExpr Expr) { - // The Dynamic TLS Module Index Relocation for a symbol defined in an - // executable is always 1. If the target Symbol is not preemptible then - // we know the offset into the TLS block at static link time. - bool NeedDynId = Sym.IsPreemptible || Config->Shared; - bool NeedDynOff = Sym.IsPreemptible; - - auto AddTlsReloc = [&](uint64_t Off, RelType Type, Symbol *Dest, bool Dyn) { - if (Dyn) - In.RelaDyn->addReloc(Type, In.Got, Off, Dest); - else - In.Got->Relocations.push_back({R_ABS, Type, Off, 0, Dest}); - }; - - // Local Dynamic is for access to module local TLS variables, while still - // being suitable for being dynamically loaded via dlopen. - // GOT[e0] is the module index, with a special value of 0 for the current - // module. GOT[e1] is unused. There only needs to be one module index entry. - if (Expr == R_TLSLD_PC && In.Got->addTlsIndex()) { - AddTlsReloc(In.Got->getTlsIndexOff(), Target->TlsModuleIndexRel, - NeedDynId ? nullptr : &Sym, NeedDynId); - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); - return 1; - } - - // Global Dynamic is the most general purpose access model. When we know - // the module index and offset of symbol in TLS block we can fill these in - // using static GOT relocations. - if (Expr == R_TLSGD_PC) { - if (In.Got->addDynTlsEntry(Sym)) { - uint64_t Off = In.Got->getGlobalDynOffset(Sym); - AddTlsReloc(Off, Target->TlsModuleIndexRel, &Sym, NeedDynId); - AddTlsReloc(Off + Config->Wordsize, Target->TlsOffsetRel, &Sym, - NeedDynOff); - } - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); - return 1; - } - return 0; -} - // Returns the number of relocations processed. template <class ELFT> static unsigned -handleTlsRelocation(RelType Type, Symbol &Sym, InputSectionBase &C, - typename ELFT::uint Offset, int64_t Addend, RelExpr Expr) { - if (!Sym.isTls()) +handleTlsRelocation(RelType type, Symbol &sym, InputSectionBase &c, + typename ELFT::uint offset, int64_t addend, RelExpr expr) { + if (!sym.isTls()) return 0; - if (Config->EMachine == EM_ARM) - return handleARMTlsRelocation<ELFT>(Type, Sym, C, Offset, Addend, Expr); - if (Config->EMachine == EM_MIPS) - return handleMipsTlsRelocation(Type, Sym, C, Offset, Addend, Expr); - - if (isRelExprOneOf<R_TLSDESC, R_AARCH64_TLSDESC_PAGE, R_TLSDESC_CALL>(Expr) && - Config->Shared) { - if (In.Got->addDynTlsEntry(Sym)) { - uint64_t Off = In.Got->getGlobalDynOffset(Sym); - In.RelaDyn->addReloc( - {Target->TlsDescRel, In.Got, Off, !Sym.IsPreemptible, &Sym, 0}); + if (config->emachine == EM_MIPS) + return handleMipsTlsRelocation(type, sym, c, offset, addend, expr); + + if (oneof<R_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC>( + expr) && + config->shared) { + if (in.got->addDynTlsEntry(sym)) { + uint64_t off = in.got->getGlobalDynOffset(sym); + mainPart->relaDyn->addReloc( + {target->tlsDescRel, in.got, off, !sym.isPreemptible, &sym, 0}); } - if (Expr != R_TLSDESC_CALL) - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); + if (expr != R_TLSDESC_CALL) + c.relocations.push_back({expr, type, offset, addend, &sym}); return 1; } - if (isRelExprOneOf<R_TLSLD_GOT, R_TLSLD_GOT_FROM_END, R_TLSLD_PC, - R_TLSLD_HINT>(Expr)) { + bool canRelax = config->emachine != EM_ARM && config->emachine != EM_RISCV; + + // If we are producing an executable and the symbol is non-preemptable, it + // must be defined and the code sequence can be relaxed to use Local-Exec. + // + // ARM and RISC-V do not support any relaxations for TLS relocations, however, + // we can omit the DTPMOD dynamic relocations and resolve them at link time + // because them are always 1. This may be necessary for static linking as + // DTPMOD may not be expected at load time. + bool isLocalInExecutable = !sym.isPreemptible && !config->shared; + + // Local Dynamic is for access to module local TLS variables, while still + // being suitable for being dynamically loaded via dlopen. GOT[e0] is the + // module index, with a special value of 0 for the current module. GOT[e1] is + // unused. There only needs to be one module index entry. + if (oneof<R_TLSLD_GOT, R_TLSLD_GOTPLT, R_TLSLD_PC, R_TLSLD_HINT>( + expr)) { // Local-Dynamic relocs can be relaxed to Local-Exec. - if (!Config->Shared) { - C.Relocations.push_back( - {Target->adjustRelaxExpr(Type, nullptr, R_RELAX_TLS_LD_TO_LE), Type, - Offset, Addend, &Sym}); - return Target->TlsGdRelaxSkip; + if (canRelax && !config->shared) { + c.relocations.push_back( + {target->adjustRelaxExpr(type, nullptr, R_RELAX_TLS_LD_TO_LE), type, + offset, addend, &sym}); + return target->getTlsGdRelaxSkip(type); } - if (Expr == R_TLSLD_HINT) + if (expr == R_TLSLD_HINT) return 1; - if (In.Got->addTlsIndex()) - In.RelaDyn->addReloc(Target->TlsModuleIndexRel, In.Got, - In.Got->getTlsIndexOff(), nullptr); - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); + if (in.got->addTlsIndex()) { + if (isLocalInExecutable) + in.got->relocations.push_back( + {R_ADDEND, target->symbolicRel, in.got->getTlsIndexOff(), 1, &sym}); + else + mainPart->relaDyn->addReloc(target->tlsModuleIndexRel, in.got, + in.got->getTlsIndexOff(), nullptr); + } + c.relocations.push_back({expr, type, offset, addend, &sym}); return 1; } // Local-Dynamic relocs can be relaxed to Local-Exec. - if (Expr == R_ABS && !Config->Shared) { - C.Relocations.push_back( - {Target->adjustRelaxExpr(Type, nullptr, R_RELAX_TLS_LD_TO_LE), Type, - Offset, Addend, &Sym}); + if (expr == R_DTPREL && !config->shared) { + c.relocations.push_back( + {target->adjustRelaxExpr(type, nullptr, R_RELAX_TLS_LD_TO_LE), type, + offset, addend, &sym}); return 1; } // Local-Dynamic sequence where offset of tls variable relative to dynamic - // thread pointer is stored in the got. - if (Expr == R_TLSLD_GOT_OFF) { - // Local-Dynamic relocs can be relaxed to local-exec - if (!Config->Shared) { - C.Relocations.push_back({R_RELAX_TLS_LD_TO_LE, Type, Offset, Addend, &Sym}); - return 1; + // thread pointer is stored in the got. This cannot be relaxed to Local-Exec. + if (expr == R_TLSLD_GOT_OFF) { + if (!sym.isInGot()) { + in.got->addEntry(sym); + uint64_t off = sym.getGotOffset(); + in.got->relocations.push_back( + {R_ABS, target->tlsOffsetRel, off, 0, &sym}); } - if (!Sym.isInGot()) { - In.Got->addEntry(Sym); - uint64_t Off = Sym.getGotOffset(); - In.Got->Relocations.push_back( - {R_ABS, Target->TlsOffsetRel, Off, 0, &Sym}); - } - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); + c.relocations.push_back({expr, type, offset, addend, &sym}); return 1; } - if (isRelExprOneOf<R_TLSDESC, R_AARCH64_TLSDESC_PAGE, R_TLSDESC_CALL, - R_TLSGD_GOT, R_TLSGD_GOT_FROM_END, R_TLSGD_PC>(Expr)) { - if (Config->Shared) { - if (In.Got->addDynTlsEntry(Sym)) { - uint64_t Off = In.Got->getGlobalDynOffset(Sym); - In.RelaDyn->addReloc(Target->TlsModuleIndexRel, In.Got, Off, &Sym); + if (oneof<R_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC, + R_TLSGD_GOT, R_TLSGD_GOTPLT, R_TLSGD_PC>(expr)) { + if (!canRelax || config->shared) { + if (in.got->addDynTlsEntry(sym)) { + uint64_t off = in.got->getGlobalDynOffset(sym); + + if (isLocalInExecutable) + // Write one to the GOT slot. + in.got->relocations.push_back( + {R_ADDEND, target->symbolicRel, off, 1, &sym}); + else + mainPart->relaDyn->addReloc(target->tlsModuleIndexRel, in.got, off, &sym); // If the symbol is preemptible we need the dynamic linker to write // the offset too. - uint64_t OffsetOff = Off + Config->Wordsize; - if (Sym.IsPreemptible) - In.RelaDyn->addReloc(Target->TlsOffsetRel, In.Got, OffsetOff, &Sym); + uint64_t offsetOff = off + config->wordsize; + if (sym.isPreemptible) + mainPart->relaDyn->addReloc(target->tlsOffsetRel, in.got, offsetOff, + &sym); else - In.Got->Relocations.push_back( - {R_ABS, Target->TlsOffsetRel, OffsetOff, 0, &Sym}); + in.got->relocations.push_back( + {R_ABS, target->tlsOffsetRel, offsetOff, 0, &sym}); } - C.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); + c.relocations.push_back({expr, type, offset, addend, &sym}); return 1; } // Global-Dynamic relocs can be relaxed to Initial-Exec or Local-Exec // depending on the symbol being locally defined or not. - if (Sym.IsPreemptible) { - C.Relocations.push_back( - {Target->adjustRelaxExpr(Type, nullptr, R_RELAX_TLS_GD_TO_IE), Type, - Offset, Addend, &Sym}); - if (!Sym.isInGot()) { - In.Got->addEntry(Sym); - In.RelaDyn->addReloc(Target->TlsGotRel, In.Got, Sym.getGotOffset(), - &Sym); + if (sym.isPreemptible) { + c.relocations.push_back( + {target->adjustRelaxExpr(type, nullptr, R_RELAX_TLS_GD_TO_IE), type, + offset, addend, &sym}); + if (!sym.isInGot()) { + in.got->addEntry(sym); + mainPart->relaDyn->addReloc(target->tlsGotRel, in.got, sym.getGotOffset(), + &sym); } } else { - C.Relocations.push_back( - {Target->adjustRelaxExpr(Type, nullptr, R_RELAX_TLS_GD_TO_LE), Type, - Offset, Addend, &Sym}); + c.relocations.push_back( + {target->adjustRelaxExpr(type, nullptr, R_RELAX_TLS_GD_TO_LE), type, + offset, addend, &sym}); } - return Target->TlsGdRelaxSkip; + return target->getTlsGdRelaxSkip(type); } // Initial-Exec relocs can be relaxed to Local-Exec if the symbol is locally // defined. - if (isRelExprOneOf<R_GOT, R_GOT_FROM_END, R_GOT_PC, R_AARCH64_GOT_PAGE_PC, - R_GOT_OFF, R_TLSIE_HINT>(Expr) && - !Config->Shared && !Sym.IsPreemptible) { - C.Relocations.push_back({R_RELAX_TLS_IE_TO_LE, Type, Offset, Addend, &Sym}); + if (oneof<R_GOT, R_GOTPLT, R_GOT_PC, R_AARCH64_GOT_PAGE_PC, R_GOT_OFF, + R_TLSIE_HINT>(expr) && + canRelax && isLocalInExecutable) { + c.relocations.push_back({R_RELAX_TLS_IE_TO_LE, type, offset, addend, &sym}); return 1; } - if (Expr == R_TLSIE_HINT) + if (expr == R_TLSIE_HINT) return 1; return 0; } -static RelType getMipsPairType(RelType Type, bool IsLocal) { - switch (Type) { +static RelType getMipsPairType(RelType type, bool isLocal) { + switch (type) { case R_MIPS_HI16: return R_MIPS_LO16; case R_MIPS_GOT16: @@ -309,9 +309,9 @@ static RelType getMipsPairType(RelType Type, bool IsLocal) { // the high 16 bits of the symbol's value. A paired R_MIPS_LO16 // relocations handle low 16 bits of the address. That allows // to allocate only one GOT entry for every 64 KBytes of local data. - return IsLocal ? R_MIPS_LO16 : R_MIPS_NONE; + return isLocal ? R_MIPS_LO16 : R_MIPS_NONE; case R_MICROMIPS_GOT16: - return IsLocal ? R_MICROMIPS_LO16 : R_MIPS_NONE; + return isLocal ? R_MICROMIPS_LO16 : R_MIPS_NONE; case R_MIPS_PCHI16: return R_MIPS_PCLO16; case R_MICROMIPS_HI16: @@ -323,40 +323,38 @@ static RelType getMipsPairType(RelType Type, bool IsLocal) { // True if non-preemptable symbol always has the same value regardless of where // the DSO is loaded. -static bool isAbsolute(const Symbol &Sym) { - if (Sym.isUndefWeak()) +static bool isAbsolute(const Symbol &sym) { + if (sym.isUndefWeak()) return true; - if (const auto *DR = dyn_cast<Defined>(&Sym)) - return DR->Section == nullptr; // Absolute symbol. + if (const auto *dr = dyn_cast<Defined>(&sym)) + return dr->section == nullptr; // Absolute symbol. return false; } -static bool isAbsoluteValue(const Symbol &Sym) { - return isAbsolute(Sym) || Sym.isTls(); +static bool isAbsoluteValue(const Symbol &sym) { + return isAbsolute(sym) || sym.isTls(); } // Returns true if Expr refers a PLT entry. -static bool needsPlt(RelExpr Expr) { - return isRelExprOneOf<R_PLT_PC, R_PPC_CALL_PLT, R_PLT, R_AARCH64_PLT_PAGE_PC, - R_GOT_PLT, R_AARCH64_GOT_PAGE_PC_PLT>(Expr); +static bool needsPlt(RelExpr expr) { + return oneof<R_PLT_PC, R_PPC32_PLTREL, R_PPC64_CALL_PLT, R_PLT>(expr); } // Returns true if Expr refers a GOT entry. Note that this function // returns false for TLS variables even though they need GOT, because // TLS variables uses GOT differently than the regular variables. -static bool needsGot(RelExpr Expr) { - return isRelExprOneOf<R_GOT, R_GOT_OFF, R_HEXAGON_GOT, R_MIPS_GOT_LOCAL_PAGE, - R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32, R_AARCH64_GOT_PAGE_PC, - R_AARCH64_GOT_PAGE_PC_PLT, R_GOT_PC, R_GOT_FROM_END, - R_GOT_PLT>(Expr); +static bool needsGot(RelExpr expr) { + return oneof<R_GOT, R_GOT_OFF, R_HEXAGON_GOT, R_MIPS_GOT_LOCAL_PAGE, + R_MIPS_GOT_OFF, R_MIPS_GOT_OFF32, R_AARCH64_GOT_PAGE_PC, + R_GOT_PC, R_GOTPLT>(expr); } // True if this expression is of the form Sym - X, where X is a position in the // file (PC, or GOT for example). -static bool isRelExpr(RelExpr Expr) { - return isRelExprOneOf<R_PC, R_GOTREL, R_GOTREL_FROM_END, R_MIPS_GOTREL, - R_PPC_CALL, R_PPC_CALL_PLT, R_AARCH64_PAGE_PC, - R_RELAX_GOT_PC>(Expr); +static bool isRelExpr(RelExpr expr) { + return oneof<R_PC, R_GOTREL, R_GOTPLTREL, R_MIPS_GOTREL, R_PPC64_CALL, + R_PPC64_RELAX_TOC, R_AARCH64_PAGE_PC, R_RELAX_GOT_PC, + R_RISCV_PC_INDIRECT>(expr); } // Returns true if a given relocation can be computed at link-time. @@ -368,43 +366,43 @@ static bool isRelExpr(RelExpr Expr) { // // If this function returns false, that means we need to emit a // dynamic relocation so that the relocation will be fixed at load-time. -static bool isStaticLinkTimeConstant(RelExpr E, RelType Type, const Symbol &Sym, - InputSectionBase &S, uint64_t RelOff) { +static bool isStaticLinkTimeConstant(RelExpr e, RelType type, const Symbol &sym, + InputSectionBase &s, uint64_t relOff) { // These expressions always compute a constant - if (isRelExprOneOf<R_GOT_FROM_END, R_GOT_OFF, R_HEXAGON_GOT, R_TLSLD_GOT_OFF, - R_MIPS_GOT_LOCAL_PAGE, R_MIPS_GOTREL, R_MIPS_GOT_OFF, - R_MIPS_GOT_OFF32, R_MIPS_GOT_GP_PC, R_MIPS_TLSGD, - R_AARCH64_GOT_PAGE_PC, R_AARCH64_GOT_PAGE_PC_PLT, R_GOT_PC, - R_GOTONLY_PC, R_GOTONLY_PC_FROM_END, R_PLT_PC, R_TLSGD_GOT, - R_TLSGD_GOT_FROM_END, R_TLSGD_PC, R_PPC_CALL_PLT, - R_TLSDESC_CALL, R_AARCH64_TLSDESC_PAGE, R_HINT, - R_TLSLD_HINT, R_TLSIE_HINT>(E)) + if (oneof<R_DTPREL, R_GOTPLT, R_GOT_OFF, R_HEXAGON_GOT, R_TLSLD_GOT_OFF, + R_MIPS_GOT_LOCAL_PAGE, R_MIPS_GOTREL, R_MIPS_GOT_OFF, + R_MIPS_GOT_OFF32, R_MIPS_GOT_GP_PC, R_MIPS_TLSGD, + R_AARCH64_GOT_PAGE_PC, R_GOT_PC, R_GOTONLY_PC, R_GOTPLTONLY_PC, + R_PLT_PC, R_TLSGD_GOT, R_TLSGD_GOTPLT, R_TLSGD_PC, R_PPC32_PLTREL, + R_PPC64_CALL_PLT, R_PPC64_RELAX_TOC, R_RISCV_ADD, R_TLSDESC_CALL, + R_TLSDESC_PC, R_AARCH64_TLSDESC_PAGE, R_HINT, R_TLSLD_HINT, + R_TLSIE_HINT>(e)) return true; // These never do, except if the entire file is position dependent or if // only the low bits are used. - if (E == R_GOT || E == R_GOT_PLT || E == R_PLT || E == R_TLSDESC) - return Target->usesOnlyLowPageBits(Type) || !Config->Pic; + if (e == R_GOT || e == R_PLT || e == R_TLSDESC) + return target->usesOnlyLowPageBits(type) || !config->isPic; - if (Sym.IsPreemptible) + if (sym.isPreemptible) return false; - if (!Config->Pic) + if (!config->isPic) return true; // The size of a non preemptible symbol is a constant. - if (E == R_SIZE) + if (e == R_SIZE) return true; // For the target and the relocation, we want to know if they are // absolute or relative. - bool AbsVal = isAbsoluteValue(Sym); - bool RelE = isRelExpr(E); - if (AbsVal && !RelE) + bool absVal = isAbsoluteValue(sym); + bool relE = isRelExpr(e); + if (absVal && !relE) return true; - if (!AbsVal && RelE) + if (!absVal && relE) return true; - if (!AbsVal && !RelE) - return Target->usesOnlyLowPageBits(Type); + if (!absVal && !relE) + return target->usesOnlyLowPageBits(type); // Relative relocation to an absolute value. This is normally unrepresentable, // but if the relocation refers to a weak undefined symbol, we allow it to @@ -414,59 +412,60 @@ static bool isStaticLinkTimeConstant(RelExpr E, RelType Type, const Symbol &Sym, // Another special case is MIPS _gp_disp symbol which represents offset // between start of a function and '_gp' value and defined as absolute just // to simplify the code. - assert(AbsVal && RelE); - if (Sym.isUndefWeak()) + assert(absVal && relE); + if (sym.isUndefWeak()) return true; - error("relocation " + toString(Type) + " cannot refer to absolute symbol: " + - toString(Sym) + getLocation(S, Sym, RelOff)); + // We set the final symbols values for linker script defined symbols later. + // They always can be computed as a link time constant. + if (sym.scriptDefined) + return true; + + error("relocation " + toString(type) + " cannot refer to absolute symbol: " + + toString(sym) + getLocation(s, sym, relOff)); return true; } -static RelExpr toPlt(RelExpr Expr) { - switch (Expr) { - case R_PPC_CALL: - return R_PPC_CALL_PLT; +static RelExpr toPlt(RelExpr expr) { + switch (expr) { + case R_PPC64_CALL: + return R_PPC64_CALL_PLT; case R_PC: return R_PLT_PC; - case R_AARCH64_PAGE_PC: - return R_AARCH64_PLT_PAGE_PC; - case R_AARCH64_GOT_PAGE_PC: - return R_AARCH64_GOT_PAGE_PC_PLT; case R_ABS: return R_PLT; - case R_GOT: - return R_GOT_PLT; default: - return Expr; + return expr; } } -static RelExpr fromPlt(RelExpr Expr) { +static RelExpr fromPlt(RelExpr expr) { // We decided not to use a plt. Optimize a reference to the plt to a // reference to the symbol itself. - switch (Expr) { + switch (expr) { case R_PLT_PC: + case R_PPC32_PLTREL: return R_PC; - case R_PPC_CALL_PLT: - return R_PPC_CALL; + case R_PPC64_CALL_PLT: + return R_PPC64_CALL; case R_PLT: return R_ABS; default: - return Expr; + return expr; } } // Returns true if a given shared symbol is in a read-only segment in a DSO. -template <class ELFT> static bool isReadOnly(SharedSymbol &SS) { - typedef typename ELFT::Phdr Elf_Phdr; +template <class ELFT> static bool isReadOnly(SharedSymbol &ss) { + using Elf_Phdr = typename ELFT::Phdr; // Determine if the symbol is read-only by scanning the DSO's program headers. - const SharedFile<ELFT> &File = SS.getFile<ELFT>(); - for (const Elf_Phdr &Phdr : check(File.getObj().program_headers())) - if ((Phdr.p_type == ELF::PT_LOAD || Phdr.p_type == ELF::PT_GNU_RELRO) && - !(Phdr.p_flags & ELF::PF_W) && SS.Value >= Phdr.p_vaddr && - SS.Value < Phdr.p_vaddr + Phdr.p_memsz) + const SharedFile &file = ss.getFile(); + for (const Elf_Phdr &phdr : + check(file.template getObj<ELFT>().program_headers())) + if ((phdr.p_type == ELF::PT_LOAD || phdr.p_type == ELF::PT_GNU_RELRO) && + !(phdr.p_flags & ELF::PF_W) && ss.value >= phdr.p_vaddr && + ss.value < phdr.p_vaddr + phdr.p_memsz) return true; return false; } @@ -477,22 +476,22 @@ template <class ELFT> static bool isReadOnly(SharedSymbol &SS) { // them are copied by a copy relocation, all of them need to be copied. // Otherwise, they would refer to different places at runtime. template <class ELFT> -static SmallSet<SharedSymbol *, 4> getSymbolsAt(SharedSymbol &SS) { - typedef typename ELFT::Sym Elf_Sym; +static SmallSet<SharedSymbol *, 4> getSymbolsAt(SharedSymbol &ss) { + using Elf_Sym = typename ELFT::Sym; - SharedFile<ELFT> &File = SS.getFile<ELFT>(); + SharedFile &file = ss.getFile(); - SmallSet<SharedSymbol *, 4> Ret; - for (const Elf_Sym &S : File.getGlobalELFSyms()) { - if (S.st_shndx == SHN_UNDEF || S.st_shndx == SHN_ABS || - S.getType() == STT_TLS || S.st_value != SS.Value) + SmallSet<SharedSymbol *, 4> ret; + for (const Elf_Sym &s : file.template getGlobalELFSyms<ELFT>()) { + if (s.st_shndx == SHN_UNDEF || s.st_shndx == SHN_ABS || + s.getType() == STT_TLS || s.st_value != ss.value) continue; - StringRef Name = check(S.getName(File.getStringTable())); - Symbol *Sym = Symtab->find(Name); - if (auto *Alias = dyn_cast_or_null<SharedSymbol>(Sym)) - Ret.insert(Alias); + StringRef name = check(s.getName(file.getStringTable())); + Symbol *sym = symtab->find(name); + if (auto *alias = dyn_cast_or_null<SharedSymbol>(sym)) + ret.insert(alias); } - return Ret; + return ret; } // When a symbol is copy relocated or we create a canonical plt entry, it is @@ -500,19 +499,21 @@ static SmallSet<SharedSymbol *, 4> getSymbolsAt(SharedSymbol &SS) { // in .bss and in the case of a canonical plt entry it is in .plt. This function // replaces the existing symbol with a Defined pointing to the appropriate // location. -static void replaceWithDefined(Symbol &Sym, SectionBase *Sec, uint64_t Value, - uint64_t Size) { - Symbol Old = Sym; - replaceSymbol<Defined>(&Sym, Sym.File, Sym.getName(), Sym.Binding, - Sym.StOther, Sym.Type, Value, Size, Sec); - Sym.PltIndex = Old.PltIndex; - Sym.GotIndex = Old.GotIndex; - Sym.VerdefIndex = Old.VerdefIndex; - Sym.PPC64BranchltIndex = Old.PPC64BranchltIndex; - Sym.IsPreemptible = true; - Sym.ExportDynamic = true; - Sym.IsUsedInRegularObj = true; - Sym.Used = true; +static void replaceWithDefined(Symbol &sym, SectionBase *sec, uint64_t value, + uint64_t size) { + Symbol old = sym; + + sym.replace(Defined{sym.file, sym.getName(), sym.binding, sym.stOther, + sym.type, value, size, sec}); + + sym.pltIndex = old.pltIndex; + sym.gotIndex = old.gotIndex; + sym.verdefIndex = old.verdefIndex; + sym.ppc64BranchltIndex = old.ppc64BranchltIndex; + sym.isPreemptible = true; + sym.exportDynamic = true; + sym.isUsedInRegularObj = true; + sym.used = true; } // Reserve space in .bss or .bss.rel.ro for copy relocation. @@ -557,29 +558,29 @@ static void replaceWithDefined(Symbol &Sym, SectionBase *Sec, uint64_t Value, // to the variable in .bss. This kind of issue is sometimes very hard to // debug. What's a solution? Instead of exporting a varaible V from a DSO, // define an accessor getV(). -template <class ELFT> static void addCopyRelSymbol(SharedSymbol &SS) { +template <class ELFT> static void addCopyRelSymbol(SharedSymbol &ss) { // Copy relocation against zero-sized symbol doesn't make sense. - uint64_t SymSize = SS.getSize(); - if (SymSize == 0 || SS.Alignment == 0) - fatal("cannot create a copy relocation for symbol " + toString(SS)); + uint64_t symSize = ss.getSize(); + if (symSize == 0 || ss.alignment == 0) + fatal("cannot create a copy relocation for symbol " + toString(ss)); // See if this symbol is in a read-only segment. If so, preserve the symbol's // memory protection by reserving space in the .bss.rel.ro section. - bool IsReadOnly = isReadOnly<ELFT>(SS); - BssSection *Sec = make<BssSection>(IsReadOnly ? ".bss.rel.ro" : ".bss", - SymSize, SS.Alignment); - if (IsReadOnly) - In.BssRelRo->getParent()->addSection(Sec); + bool isRO = isReadOnly<ELFT>(ss); + BssSection *sec = + make<BssSection>(isRO ? ".bss.rel.ro" : ".bss", symSize, ss.alignment); + if (isRO) + in.bssRelRo->getParent()->addSection(sec); else - In.Bss->getParent()->addSection(Sec); + in.bss->getParent()->addSection(sec); // Look through the DSO's dynamic symbol table for aliases and create a // dynamic symbol for each one. This causes the copy relocation to correctly // interpose any aliases. - for (SharedSymbol *Sym : getSymbolsAt<ELFT>(SS)) - replaceWithDefined(*Sym, Sec, 0, Sym->Size); + for (SharedSymbol *sym : getSymbolsAt<ELFT>(ss)) + replaceWithDefined(*sym, sec, 0, sym->size); - In.RelaDyn->addReloc(Target->CopyRel, Sec, 0, &SS); + mainPart->relaDyn->addReloc(target->copyRel, sec, 0, &ss); } // MIPS has an odd notion of "paired" relocations to calculate addends. @@ -587,34 +588,34 @@ template <class ELFT> static void addCopyRelSymbol(SharedSymbol &SS) { // R_MIPS_LO16 relocation after that, and an addend is calculated using // the two relocations. template <class ELFT, class RelTy> -static int64_t computeMipsAddend(const RelTy &Rel, const RelTy *End, - InputSectionBase &Sec, RelExpr Expr, - bool IsLocal) { - if (Expr == R_MIPS_GOTREL && IsLocal) - return Sec.getFile<ELFT>()->MipsGp0; +static int64_t computeMipsAddend(const RelTy &rel, const RelTy *end, + InputSectionBase &sec, RelExpr expr, + bool isLocal) { + if (expr == R_MIPS_GOTREL && isLocal) + return sec.getFile<ELFT>()->mipsGp0; // The ABI says that the paired relocation is used only for REL. // See p. 4-17 at ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf if (RelTy::IsRela) return 0; - RelType Type = Rel.getType(Config->IsMips64EL); - uint32_t PairTy = getMipsPairType(Type, IsLocal); - if (PairTy == R_MIPS_NONE) + RelType type = rel.getType(config->isMips64EL); + uint32_t pairTy = getMipsPairType(type, isLocal); + if (pairTy == R_MIPS_NONE) return 0; - const uint8_t *Buf = Sec.data().data(); - uint32_t SymIndex = Rel.getSymbol(Config->IsMips64EL); + const uint8_t *buf = sec.data().data(); + uint32_t symIndex = rel.getSymbol(config->isMips64EL); // To make things worse, paired relocations might not be contiguous in // the relocation table, so we need to do linear search. *sigh* - for (const RelTy *RI = &Rel; RI != End; ++RI) - if (RI->getType(Config->IsMips64EL) == PairTy && - RI->getSymbol(Config->IsMips64EL) == SymIndex) - return Target->getImplicitAddend(Buf + RI->r_offset, PairTy); + for (const RelTy *ri = &rel; ri != end; ++ri) + if (ri->getType(config->isMips64EL) == pairTy && + ri->getSymbol(config->isMips64EL) == symIndex) + return target->getImplicitAddend(buf + ri->r_offset, pairTy); - warn("can't find matching " + toString(PairTy) + " relocation for " + - toString(Type)); + warn("can't find matching " + toString(pairTy) + " relocation for " + + toString(type)); return 0; } @@ -622,59 +623,174 @@ static int64_t computeMipsAddend(const RelTy &Rel, const RelTy *End, // is in a relocation itself. If it is REL, we need to read it from an // input section. template <class ELFT, class RelTy> -static int64_t computeAddend(const RelTy &Rel, const RelTy *End, - InputSectionBase &Sec, RelExpr Expr, - bool IsLocal) { - int64_t Addend; - RelType Type = Rel.getType(Config->IsMips64EL); +static int64_t computeAddend(const RelTy &rel, const RelTy *end, + InputSectionBase &sec, RelExpr expr, + bool isLocal) { + int64_t addend; + RelType type = rel.getType(config->isMips64EL); if (RelTy::IsRela) { - Addend = getAddend<ELFT>(Rel); + addend = getAddend<ELFT>(rel); } else { - const uint8_t *Buf = Sec.data().data(); - Addend = Target->getImplicitAddend(Buf + Rel.r_offset, Type); + const uint8_t *buf = sec.data().data(); + addend = target->getImplicitAddend(buf + rel.r_offset, type); } - if (Config->EMachine == EM_PPC64 && Config->Pic && Type == R_PPC64_TOC) - Addend += getPPC64TocBase(); - if (Config->EMachine == EM_MIPS) - Addend += computeMipsAddend<ELFT>(Rel, End, Sec, Expr, IsLocal); + if (config->emachine == EM_PPC64 && config->isPic && type == R_PPC64_TOC) + addend += getPPC64TocBase(); + if (config->emachine == EM_MIPS) + addend += computeMipsAddend<ELFT>(rel, end, sec, expr, isLocal); - return Addend; + return addend; } -// Report an undefined symbol if necessary. -// Returns true if this function printed out an error message. -static bool maybeReportUndefined(Symbol &Sym, InputSectionBase &Sec, - uint64_t Offset) { - if (Sym.isLocal() || !Sym.isUndefined() || Sym.isWeak()) - return false; +// Custom error message if Sym is defined in a discarded section. +template <class ELFT> +static std::string maybeReportDiscarded(Undefined &sym) { + auto *file = dyn_cast_or_null<ObjFile<ELFT>>(sym.file); + if (!file || !sym.discardedSecIdx || + file->getSections()[sym.discardedSecIdx] != &InputSection::discarded) + return ""; + ArrayRef<Elf_Shdr_Impl<ELFT>> objSections = + CHECK(file->getObj().sections(), file); + + std::string msg; + if (sym.type == ELF::STT_SECTION) { + msg = "relocation refers to a discarded section: "; + msg += CHECK( + file->getObj().getSectionName(&objSections[sym.discardedSecIdx]), file); + } else { + msg = "relocation refers to a symbol in a discarded section: " + + toString(sym); + } + msg += "\n>>> defined in " + toString(file); + + Elf_Shdr_Impl<ELFT> elfSec = objSections[sym.discardedSecIdx - 1]; + if (elfSec.sh_type != SHT_GROUP) + return msg; + + // If the discarded section is a COMDAT. + StringRef signature = file->getShtGroupSignature(objSections, elfSec); + if (const InputFile *prevailing = + symtab->comdatGroups.lookup(CachedHashStringRef(signature))) + msg += "\n>>> section group signature: " + signature.str() + + "\n>>> prevailing definition is in " + toString(prevailing); + return msg; +} - bool CanBeExternal = - Sym.computeBinding() != STB_LOCAL && Sym.Visibility == STV_DEFAULT; - if (Config->UnresolvedSymbols == UnresolvedPolicy::Ignore && CanBeExternal) - return false; +// Undefined diagnostics are collected in a vector and emitted once all of +// them are known, so that some postprocessing on the list of undefined symbols +// can happen before lld emits diagnostics. +struct UndefinedDiag { + Symbol *sym; + struct Loc { + InputSectionBase *sec; + uint64_t offset; + }; + std::vector<Loc> locs; + bool isWarning; +}; + +static std::vector<UndefinedDiag> undefs; + +template <class ELFT> +static void reportUndefinedSymbol(const UndefinedDiag &undef) { + Symbol &sym = *undef.sym; + + auto visibility = [&]() -> std::string { + switch (sym.visibility) { + case STV_INTERNAL: + return "internal "; + case STV_HIDDEN: + return "hidden "; + case STV_PROTECTED: + return "protected "; + default: + return ""; + } + }; - std::string Msg = - "undefined symbol: " + toString(Sym) + "\n>>> referenced by "; + std::string msg = maybeReportDiscarded<ELFT>(cast<Undefined>(sym)); + if (msg.empty()) + msg = "undefined " + visibility() + "symbol: " + toString(sym); + + const size_t maxUndefReferences = 10; + size_t i = 0; + for (UndefinedDiag::Loc l : undef.locs) { + if (i >= maxUndefReferences) + break; + InputSectionBase &sec = *l.sec; + uint64_t offset = l.offset; + + msg += "\n>>> referenced by "; + std::string src = sec.getSrcMsg(sym, offset); + if (!src.empty()) + msg += src + "\n>>> "; + msg += sec.getObjMsg(offset); + i++; + } - std::string Src = Sec.getSrcMsg(Sym, Offset); - if (!Src.empty()) - Msg += Src + "\n>>> "; - Msg += Sec.getObjMsg(Offset); + if (i < undef.locs.size()) + msg += ("\n>>> referenced " + Twine(undef.locs.size() - i) + " more times") + .str(); - if (Sym.getName().startswith("_ZTV")) - Msg += "\nthe vtable symbol may be undefined because the class is missing " + if (sym.getName().startswith("_ZTV")) + msg += "\nthe vtable symbol may be undefined because the class is missing " "its key function (see https://lld.llvm.org/missingkeyfunction)"; - if ((Config->UnresolvedSymbols == UnresolvedPolicy::Warn && CanBeExternal) || - Config->NoinhibitExec) { - warn(Msg); - return false; + if (undef.isWarning) + warn(msg); + else + error(msg); +} + +template <class ELFT> void elf::reportUndefinedSymbols() { + // Find the first "undefined symbol" diagnostic for each diagnostic, and + // collect all "referenced from" lines at the first diagnostic. + DenseMap<Symbol *, UndefinedDiag *> firstRef; + for (UndefinedDiag &undef : undefs) { + assert(undef.locs.size() == 1); + if (UndefinedDiag *canon = firstRef.lookup(undef.sym)) { + canon->locs.push_back(undef.locs[0]); + undef.locs.clear(); + } else + firstRef[undef.sym] = &undef; } - error(Msg); - return true; + for (const UndefinedDiag &undef : undefs) { + if (!undef.locs.empty()) + reportUndefinedSymbol<ELFT>(undef); + } + undefs.clear(); +} + +// Report an undefined symbol if necessary. +// Returns true if the undefined symbol will produce an error message. +template <class ELFT> +static bool maybeReportUndefined(Symbol &sym, InputSectionBase &sec, + uint64_t offset) { + if (!sym.isUndefined() || sym.isWeak()) + return false; + + bool canBeExternal = !sym.isLocal() && sym.computeBinding() != STB_LOCAL && + sym.visibility == STV_DEFAULT; + if (config->unresolvedSymbols == UnresolvedPolicy::Ignore && canBeExternal) + return false; + + // clang (as of 2019-06-12) / gcc (as of 8.2.1) PPC64 may emit a .rela.toc + // which references a switch table in a discarded .rodata/.text section. The + // .toc and the .rela.toc are incorrectly not placed in the comdat. The ELF + // spec says references from outside the group to a STB_LOCAL symbol are not + // allowed. Work around the bug. + if (config->emachine == EM_PPC64 && + cast<Undefined>(sym).discardedSecIdx != 0 && sec.name == ".toc") + return false; + + bool isWarning = + (config->unresolvedSymbols == UnresolvedPolicy::Warn && canBeExternal) || + config->noinhibitExec; + undefs.push_back({&sym, {{&sec, offset}}, isWarning}); + return !isWarning; } // MIPS N32 ABI treats series of successive relocations with the same offset @@ -682,14 +798,14 @@ static bool maybeReportUndefined(Symbol &Sym, InputSectionBase &Sec, // packs all relocations into the single relocation record. Here we emulate // this for the N32 ABI. Iterate over relocation with the same offset and put // theirs types into the single bit-set. -template <class RelTy> static RelType getMipsN32RelType(RelTy *&Rel, RelTy *End) { - RelType Type = 0; - uint64_t Offset = Rel->r_offset; - - int N = 0; - while (Rel != End && Rel->r_offset == Offset) - Type |= (Rel++)->getType(Config->IsMips64EL) << (8 * N++); - return Type; +template <class RelTy> static RelType getMipsN32RelType(RelTy *&rel, RelTy *end) { + RelType type = 0; + uint64_t offset = rel->r_offset; + + int n = 0; + while (rel != end && rel->r_offset == offset) + type |= (rel++)->getType(config->isMips64EL) << (8 * n++); + return type; } // .eh_frame sections are mergeable input sections, so their input @@ -706,77 +822,72 @@ template <class RelTy> static RelType getMipsN32RelType(RelTy *&Rel, RelTy *End) namespace { class OffsetGetter { public: - explicit OffsetGetter(InputSectionBase &Sec) { - if (auto *Eh = dyn_cast<EhInputSection>(&Sec)) - Pieces = Eh->Pieces; + explicit OffsetGetter(InputSectionBase &sec) { + if (auto *eh = dyn_cast<EhInputSection>(&sec)) + pieces = eh->pieces; } // Translates offsets in input sections to offsets in output sections. // Given offset must increase monotonically. We assume that Piece is - // sorted by InputOff. - uint64_t get(uint64_t Off) { - if (Pieces.empty()) - return Off; - - while (I != Pieces.size() && Pieces[I].InputOff + Pieces[I].Size <= Off) - ++I; - if (I == Pieces.size()) + // sorted by inputOff. + uint64_t get(uint64_t off) { + if (pieces.empty()) + return off; + + while (i != pieces.size() && pieces[i].inputOff + pieces[i].size <= off) + ++i; + if (i == pieces.size()) fatal(".eh_frame: relocation is not in any piece"); // Pieces must be contiguous, so there must be no holes in between. - assert(Pieces[I].InputOff <= Off && "Relocation not in any piece"); + assert(pieces[i].inputOff <= off && "Relocation not in any piece"); // Offset -1 means that the piece is dead (i.e. garbage collected). - if (Pieces[I].OutputOff == -1) + if (pieces[i].outputOff == -1) return -1; - return Pieces[I].OutputOff + Off - Pieces[I].InputOff; + return pieces[i].outputOff + off - pieces[i].inputOff; } private: - ArrayRef<EhSectionPiece> Pieces; - size_t I = 0; + ArrayRef<EhSectionPiece> pieces; + size_t i = 0; }; } // namespace -static void addRelativeReloc(InputSectionBase *IS, uint64_t OffsetInSec, - Symbol *Sym, int64_t Addend, RelExpr Expr, - RelType Type) { - // Add a relative relocation. If RelrDyn section is enabled, and the +static void addRelativeReloc(InputSectionBase *isec, uint64_t offsetInSec, + Symbol *sym, int64_t addend, RelExpr expr, + RelType type) { + Partition &part = isec->getPartition(); + + // Add a relative relocation. If relrDyn section is enabled, and the // relocation offset is guaranteed to be even, add the relocation to - // the RelrDyn section, otherwise add it to the RelaDyn section. - // RelrDyn sections don't support odd offsets. Also, RelrDyn sections + // the relrDyn section, otherwise add it to the relaDyn section. + // relrDyn sections don't support odd offsets. Also, relrDyn sections // don't store the addend values, so we must write it to the relocated // address. - if (In.RelrDyn && IS->Alignment >= 2 && OffsetInSec % 2 == 0) { - IS->Relocations.push_back({Expr, Type, OffsetInSec, Addend, Sym}); - In.RelrDyn->Relocs.push_back({IS, OffsetInSec}); + if (part.relrDyn && isec->alignment >= 2 && offsetInSec % 2 == 0) { + isec->relocations.push_back({expr, type, offsetInSec, addend, sym}); + part.relrDyn->relocs.push_back({isec, offsetInSec}); return; } - In.RelaDyn->addReloc(Target->RelativeRel, IS, OffsetInSec, Sym, Addend, Expr, - Type); + part.relaDyn->addReloc(target->relativeRel, isec, offsetInSec, sym, addend, + expr, type); } template <class ELFT, class GotPltSection> -static void addPltEntry(PltSection *Plt, GotPltSection *GotPlt, - RelocationBaseSection *Rel, RelType Type, Symbol &Sym) { - Plt->addEntry<ELFT>(Sym); - GotPlt->addEntry(Sym); - Rel->addReloc( - {Type, GotPlt, Sym.getGotPltOffset(), !Sym.IsPreemptible, &Sym, 0}); +static void addPltEntry(PltSection *plt, GotPltSection *gotPlt, + RelocationBaseSection *rel, RelType type, Symbol &sym) { + plt->addEntry<ELFT>(sym); + gotPlt->addEntry(sym); + rel->addReloc( + {type, gotPlt, sym.getGotPltOffset(), !sym.isPreemptible, &sym, 0}); } -template <class ELFT> static void addGotEntry(Symbol &Sym) { - In.Got->addEntry(Sym); - - RelExpr Expr; - if (Sym.isTls()) - Expr = R_TLS; - else if (Sym.isGnuIFunc()) - Expr = R_PLT; - else - Expr = R_ABS; +static void addGotEntry(Symbol &sym) { + in.got->addEntry(sym); - uint64_t Off = Sym.getGotOffset(); + RelExpr expr = sym.isTls() ? R_TLS : R_ABS; + uint64_t off = sym.getGotOffset(); // If a GOT slot value can be calculated at link-time, which is now, // we can just fill that out. @@ -785,42 +896,42 @@ template <class ELFT> static void addGotEntry(Symbol &Sym) { // add a static relocation to a Relocations vector so that // InputSection::relocate will do the work for us. We may be able // to just write a value now, but it is a TODO.) - bool IsLinkTimeConstant = - !Sym.IsPreemptible && (!Config->Pic || isAbsolute(Sym)); - if (IsLinkTimeConstant) { - In.Got->Relocations.push_back({Expr, Target->GotRel, Off, 0, &Sym}); + bool isLinkTimeConstant = + !sym.isPreemptible && (!config->isPic || isAbsolute(sym)); + if (isLinkTimeConstant) { + in.got->relocations.push_back({expr, target->symbolicRel, off, 0, &sym}); return; } // Otherwise, we emit a dynamic relocation to .rel[a].dyn so that // the GOT slot will be fixed at load-time. - if (!Sym.isTls() && !Sym.IsPreemptible && Config->Pic && !isAbsolute(Sym)) { - addRelativeReloc(In.Got, Off, &Sym, 0, R_ABS, Target->GotRel); + if (!sym.isTls() && !sym.isPreemptible && config->isPic && !isAbsolute(sym)) { + addRelativeReloc(in.got, off, &sym, 0, R_ABS, target->symbolicRel); return; } - In.RelaDyn->addReloc(Sym.isTls() ? Target->TlsGotRel : Target->GotRel, In.Got, - Off, &Sym, 0, Sym.IsPreemptible ? R_ADDEND : R_ABS, - Target->GotRel); + mainPart->relaDyn->addReloc( + sym.isTls() ? target->tlsGotRel : target->gotRel, in.got, off, &sym, 0, + sym.isPreemptible ? R_ADDEND : R_ABS, target->symbolicRel); } // Return true if we can define a symbol in the executable that // contains the value/function of a symbol defined in a shared // library. -static bool canDefineSymbolInExecutable(Symbol &Sym) { +static bool canDefineSymbolInExecutable(Symbol &sym) { // If the symbol has default visibility the symbol defined in the // executable will preempt it. // Note that we want the visibility of the shared symbol itself, not // the visibility of the symbol in the output file we are producing. That is - // why we use Sym.StOther. - if ((Sym.StOther & 0x3) == STV_DEFAULT) + // why we use Sym.stOther. + if ((sym.stOther & 0x3) == STV_DEFAULT) return true; // If we are allowed to break address equality of functions, defining // a plt entry will allow the program to call the function in the // .so, but the .so and the executable will no agree on the address // of the function. Similar logic for objects. - return ((Sym.isFunc() && Config->IgnoreFunctionAddressEquality) || - (Sym.isObject() && Config->IgnoreDataAddressEquality)); + return ((sym.isFunc() && config->ignoreFunctionAddressEquality) || + (sym.isObject() && config->ignoreDataAddressEquality)); } // The reason we have to do this early scan is as follows @@ -837,23 +948,33 @@ static bool canDefineSymbolInExecutable(Symbol &Sym) { // complicates things for the dynamic linker and means we would have to reserve // space for the extra PT_LOAD even if we end up not using it. template <class ELFT, class RelTy> -static void processRelocAux(InputSectionBase &Sec, RelExpr Expr, RelType Type, - uint64_t Offset, Symbol &Sym, const RelTy &Rel, - int64_t Addend) { - if (isStaticLinkTimeConstant(Expr, Type, Sym, Sec, Offset)) { - Sec.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); +static void processRelocAux(InputSectionBase &sec, RelExpr expr, RelType type, + uint64_t offset, Symbol &sym, const RelTy &rel, + int64_t addend) { + // If the relocation is known to be a link-time constant, we know no dynamic + // relocation will be created, pass the control to relocateAlloc() or + // relocateNonAlloc() to resolve it. + // + // The behavior of an undefined weak reference is implementation defined. If + // the relocation is to a weak undef, and we are producing an executable, let + // relocate{,Non}Alloc() resolve it. + if (isStaticLinkTimeConstant(expr, type, sym, sec, offset) || + (!config->shared && sym.isUndefWeak())) { + sec.relocations.push_back({expr, type, offset, addend, &sym}); return; } - bool CanWrite = (Sec.Flags & SHF_WRITE) || !Config->ZText; - if (CanWrite) { - // R_GOT refers to a position in the got, even if the symbol is preemptible. - bool IsPreemptibleValue = Sym.IsPreemptible && Expr != R_GOT; - if (!IsPreemptibleValue) { - addRelativeReloc(&Sec, Offset, &Sym, Addend, Expr, Type); + bool canWrite = (sec.flags & SHF_WRITE) || !config->zText; + if (canWrite) { + RelType rel = target->getDynRel(type); + if (expr == R_GOT || (rel == target->symbolicRel && !sym.isPreemptible)) { + addRelativeReloc(&sec, offset, &sym, addend, expr, type); return; - } else if (RelType Rel = Target->getDynRel(Type)) { - In.RelaDyn->addReloc(Rel, &Sec, Offset, &Sym, Addend, R_ADDEND, Type); + } else if (rel != 0) { + if (config->emachine == EM_MIPS && rel == target->symbolicRel) + rel = target->relativeRel; + sec.getPartition().relaDyn->addReloc(rel, &sec, offset, &sym, addend, + R_ADDEND, type); // MIPS ABI turns using of GOT and dynamic relocations inside out. // While regular ABI uses dynamic relocations to fill up GOT entries @@ -870,62 +991,62 @@ static void processRelocAux(InputSectionBase &Sec, RelExpr Expr, RelType Type, // to the GOT entry and reads the GOT entry when it needs to perform // a dynamic relocation. // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf p.4-19 - if (Config->EMachine == EM_MIPS) - In.MipsGot->addEntry(*Sec.File, Sym, Addend, Expr); + if (config->emachine == EM_MIPS) + in.mipsGot->addEntry(*sec.file, sym, addend, expr); return; } } - // If the relocation is to a weak undef, and we are producing - // executable, give up on it and produce a non preemptible 0. - if (!Config->Shared && Sym.isUndefWeak()) { - Sec.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); - return; - } - - if (!CanWrite && (Config->Pic && !isRelExpr(Expr))) { + if (!canWrite && (config->isPic && !isRelExpr(expr))) { error( - "can't create dynamic relocation " + toString(Type) + " against " + - (Sym.getName().empty() ? "local symbol" : "symbol: " + toString(Sym)) + + "can't create dynamic relocation " + toString(type) + " against " + + (sym.getName().empty() ? "local symbol" : "symbol: " + toString(sym)) + " in readonly segment; recompile object files with -fPIC " "or pass '-Wl,-z,notext' to allow text relocations in the output" + - getLocation(Sec, Sym, Offset)); + getLocation(sec, sym, offset)); return; } - // Copy relocations are only possible if we are creating an executable. - if (Config->Shared) { - errorOrWarn("relocation " + toString(Type) + - " cannot be used against symbol " + toString(Sym) + - "; recompile with -fPIC" + getLocation(Sec, Sym, Offset)); + // Copy relocations (for STT_OBJECT) and canonical PLT (for STT_FUNC) are only + // possible in an executable. + // + // Among R_ABS relocatoin types, symbolicRel has the same size as the word + // size. Others have fewer bits and may cause runtime overflow in -pie/-shared + // mode. Disallow them. + if (config->shared || + (config->pie && expr == R_ABS && type != target->symbolicRel)) { + errorOrWarn( + "relocation " + toString(type) + " cannot be used against " + + (sym.getName().empty() ? "local symbol" : "symbol " + toString(sym)) + + "; recompile with -fPIC" + getLocation(sec, sym, offset)); return; } // If the symbol is undefined we already reported any relevant errors. - if (Sym.isUndefined()) + if (sym.isUndefined()) return; - if (!canDefineSymbolInExecutable(Sym)) { - error("cannot preempt symbol: " + toString(Sym) + - getLocation(Sec, Sym, Offset)); + if (!canDefineSymbolInExecutable(sym)) { + error("cannot preempt symbol: " + toString(sym) + + getLocation(sec, sym, offset)); return; } - if (Sym.isObject()) { + if (sym.isObject()) { // Produce a copy relocation. - if (auto *SS = dyn_cast<SharedSymbol>(&Sym)) { - if (!Config->ZCopyreloc) - error("unresolvable relocation " + toString(Type) + - " against symbol '" + toString(*SS) + + if (auto *ss = dyn_cast<SharedSymbol>(&sym)) { + if (!config->zCopyreloc) + error("unresolvable relocation " + toString(type) + + " against symbol '" + toString(*ss) + "'; recompile with -fPIC or remove '-z nocopyreloc'" + - getLocation(Sec, Sym, Offset)); - addCopyRelSymbol<ELFT>(*SS); + getLocation(sec, sym, offset)); + addCopyRelSymbol<ELFT>(*ss); } - Sec.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); + sec.relocations.push_back({expr, type, offset, addend, &sym}); return; } - if (Sym.isFunc()) { + if (sym.isFunc()) { // This handles a non PIC program call to function in a shared library. In // an ideal world, we could just report an error saying the relocation can // overflow at runtime. In the real world with glibc, crt1.o has a @@ -953,167 +1074,333 @@ static void processRelocAux(InputSectionBase &Sec, RelExpr Expr, RelType Type, // compiled without -fPIE/-fPIC and doesn't maintain ebx. // * If a library definition gets preempted to the executable, it will have // the wrong ebx value. - if (Config->Pie && Config->EMachine == EM_386) - errorOrWarn("symbol '" + toString(Sym) + + if (config->pie && config->emachine == EM_386) + errorOrWarn("symbol '" + toString(sym) + "' cannot be preempted; recompile with -fPIE" + - getLocation(Sec, Sym, Offset)); - if (!Sym.isInPlt()) - addPltEntry<ELFT>(In.Plt, In.GotPlt, In.RelaPlt, Target->PltRel, Sym); - if (!Sym.isDefined()) - replaceWithDefined(Sym, In.Plt, getPltEntryOffset(Sym.PltIndex), 0); - Sym.NeedsPltAddr = true; - Sec.Relocations.push_back({Expr, Type, Offset, Addend, &Sym}); + getLocation(sec, sym, offset)); + if (!sym.isInPlt()) + addPltEntry<ELFT>(in.plt, in.gotPlt, in.relaPlt, target->pltRel, sym); + if (!sym.isDefined()) + replaceWithDefined( + sym, in.plt, + target->pltHeaderSize + target->pltEntrySize * sym.pltIndex, 0); + sym.needsPltAddr = true; + sec.relocations.push_back({expr, type, offset, addend, &sym}); return; } - errorOrWarn("symbol '" + toString(Sym) + "' has no type" + - getLocation(Sec, Sym, Offset)); + errorOrWarn("symbol '" + toString(sym) + "' has no type" + + getLocation(sec, sym, offset)); } +struct IRelativeReloc { + RelType type; + InputSectionBase *sec; + uint64_t offset; + Symbol *sym; +}; + +static std::vector<IRelativeReloc> iRelativeRelocs; + template <class ELFT, class RelTy> -static void scanReloc(InputSectionBase &Sec, OffsetGetter &GetOffset, RelTy *&I, - RelTy *End) { - const RelTy &Rel = *I; - Symbol &Sym = Sec.getFile<ELFT>()->getRelocTargetSym(Rel); - RelType Type; +static void scanReloc(InputSectionBase &sec, OffsetGetter &getOffset, RelTy *&i, + RelTy *end) { + const RelTy &rel = *i; + uint32_t symIndex = rel.getSymbol(config->isMips64EL); + Symbol &sym = sec.getFile<ELFT>()->getSymbol(symIndex); + RelType type; // Deal with MIPS oddity. - if (Config->MipsN32Abi) { - Type = getMipsN32RelType(I, End); + if (config->mipsN32Abi) { + type = getMipsN32RelType(i, end); } else { - Type = Rel.getType(Config->IsMips64EL); - ++I; + type = rel.getType(config->isMips64EL); + ++i; } // Get an offset in an output section this relocation is applied to. - uint64_t Offset = GetOffset.get(Rel.r_offset); - if (Offset == uint64_t(-1)) + uint64_t offset = getOffset.get(rel.r_offset); + if (offset == uint64_t(-1)) return; - // Skip if the target symbol is an erroneous undefined symbol. - if (maybeReportUndefined(Sym, Sec, Rel.r_offset)) + // Error if the target symbol is undefined. Symbol index 0 may be used by + // marker relocations, e.g. R_*_NONE and R_ARM_V4BX. Don't error on them. + if (symIndex != 0 && maybeReportUndefined<ELFT>(sym, sec, rel.r_offset)) return; - const uint8_t *RelocatedAddr = Sec.data().begin() + Rel.r_offset; - RelExpr Expr = Target->getRelExpr(Type, Sym, RelocatedAddr); + const uint8_t *relocatedAddr = sec.data().begin() + rel.r_offset; + RelExpr expr = target->getRelExpr(type, sym, relocatedAddr); // Ignore "hint" relocations because they are only markers for relaxation. - if (isRelExprOneOf<R_HINT, R_NONE>(Expr)) + if (oneof<R_HINT, R_NONE>(expr)) return; - // Strenghten or relax relocations. - // - // GNU ifunc symbols must be accessed via PLT because their addresses - // are determined by runtime. + // We can separate the small code model relocations into 2 categories: + // 1) Those that access the compiler generated .toc sections. + // 2) Those that access the linker allocated got entries. + // lld allocates got entries to symbols on demand. Since we don't try to sort + // the got entries in any way, we don't have to track which objects have + // got-based small code model relocs. The .toc sections get placed after the + // end of the linker allocated .got section and we do sort those so sections + // addressed with small code model relocations come first. + if (config->emachine == EM_PPC64 && isPPC64SmallCodeModelTocReloc(type)) + sec.file->ppc64SmallCodeModelTocRelocs = true; + + if (sym.isGnuIFunc() && !config->zText && config->warnIfuncTextrel) { + warn("using ifunc symbols when text relocations are allowed may produce " + "a binary that will segfault, if the object file is linked with " + "old version of glibc (glibc 2.28 and earlier). If this applies to " + "you, consider recompiling the object files without -fPIC and " + "without -Wl,-z,notext option. Use -no-warn-ifunc-textrel to " + "turn off this warning." + + getLocation(sec, sym, offset)); + } + + // Read an addend. + int64_t addend = computeAddend<ELFT>(rel, end, sec, expr, sym.isLocal()); + + // Relax relocations. // - // On the other hand, if we know that a PLT entry will be resolved within - // the same ELF module, we can skip PLT access and directly jump to the - // destination function. For example, if we are linking a main exectuable, - // all dynamic symbols that can be resolved within the executable will - // actually be resolved that way at runtime, because the main exectuable - // is always at the beginning of a search list. We can leverage that fact. - if (Sym.isGnuIFunc()) { - if (!Config->ZText && Config->WarnIfuncTextrel) { - warn("using ifunc symbols when text relocations are allowed may produce " - "a binary that will segfault, if the object file is linked with " - "old version of glibc (glibc 2.28 and earlier). If this applies to " - "you, consider recompiling the object files without -fPIC and " - "without -Wl,-z,notext option. Use -no-warn-ifunc-textrel to " - "turn off this warning." + - getLocation(Sec, Sym, Offset)); + // If we know that a PLT entry will be resolved within the same ELF module, we + // can skip PLT access and directly jump to the destination function. For + // example, if we are linking a main exectuable, all dynamic symbols that can + // be resolved within the executable will actually be resolved that way at + // runtime, because the main exectuable is always at the beginning of a search + // list. We can leverage that fact. + if (!sym.isPreemptible && (!sym.isGnuIFunc() || config->zIfuncNoplt)) { + if (expr == R_GOT_PC && !isAbsoluteValue(sym)) { + expr = target->adjustRelaxExpr(type, relocatedAddr, expr); + } else { + // Addend of R_PPC_PLTREL24 is used to choose call stub type. It should be + // ignored if optimized to R_PC. + if (config->emachine == EM_PPC && expr == R_PPC32_PLTREL) + addend = 0; + expr = fromPlt(expr); } - Expr = toPlt(Expr); - } else if (!Sym.IsPreemptible && Expr == R_GOT_PC && !isAbsoluteValue(Sym)) { - Expr = Target->adjustRelaxExpr(Type, RelocatedAddr, Expr); - } else if (!Sym.IsPreemptible) { - Expr = fromPlt(Expr); } - // This relocation does not require got entry, but it is relative to got and - // needs it to be created. Here we request for that. - if (isRelExprOneOf<R_GOTONLY_PC, R_GOTONLY_PC_FROM_END, R_GOTREL, - R_GOTREL_FROM_END, R_PPC_TOC>(Expr)) - In.Got->HasGotOffRel = true; - - // Read an addend. - int64_t Addend = computeAddend<ELFT>(Rel, End, Sec, Expr, Sym.isLocal()); + // If the relocation does not emit a GOT or GOTPLT entry but its computation + // uses their addresses, we need GOT or GOTPLT to be created. + // + // The 4 types that relative GOTPLT are all x86 and x86-64 specific. + if (oneof<R_GOTPLTONLY_PC, R_GOTPLTREL, R_GOTPLT, R_TLSGD_GOTPLT>(expr)) { + in.gotPlt->hasGotPltOffRel = true; + } else if (oneof<R_GOTONLY_PC, R_GOTREL, R_PPC64_TOCBASE, R_PPC64_RELAX_TOC>( + expr)) { + in.got->hasGotOffRel = true; + } // Process some TLS relocations, including relaxing TLS relocations. // Note that this function does not handle all TLS relocations. - if (unsigned Processed = - handleTlsRelocation<ELFT>(Type, Sym, Sec, Offset, Addend, Expr)) { - I += (Processed - 1); + if (unsigned processed = + handleTlsRelocation<ELFT>(type, sym, sec, offset, addend, expr)) { + i += (processed - 1); return; } - // If a relocation needs PLT, we create PLT and GOTPLT slots for the symbol. - if (needsPlt(Expr) && !Sym.isInPlt()) { - if (Sym.isGnuIFunc() && !Sym.IsPreemptible) - addPltEntry<ELFT>(In.Iplt, In.IgotPlt, In.RelaIplt, Target->IRelativeRel, - Sym); - else - addPltEntry<ELFT>(In.Plt, In.GotPlt, In.RelaPlt, Target->PltRel, Sym); + // We were asked not to generate PLT entries for ifuncs. Instead, pass the + // direct relocation on through. + if (sym.isGnuIFunc() && config->zIfuncNoplt) { + sym.exportDynamic = true; + mainPart->relaDyn->addReloc(type, &sec, offset, &sym, addend, R_ADDEND, type); + return; } - // Create a GOT slot if a relocation needs GOT. - if (needsGot(Expr)) { - if (Config->EMachine == EM_MIPS) { - // MIPS ABI has special rules to process GOT entries and doesn't - // require relocation entries for them. A special case is TLS - // relocations. In that case dynamic loader applies dynamic - // relocations to initialize TLS GOT entries. - // See "Global Offset Table" in Chapter 5 in the following document - // for detailed description: - // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf - In.MipsGot->addEntry(*Sec.File, Sym, Addend, Expr); - } else if (!Sym.isInGot()) { - addGotEntry<ELFT>(Sym); + // Non-preemptible ifuncs require special handling. First, handle the usual + // case where the symbol isn't one of these. + if (!sym.isGnuIFunc() || sym.isPreemptible) { + // If a relocation needs PLT, we create PLT and GOTPLT slots for the symbol. + if (needsPlt(expr) && !sym.isInPlt()) + addPltEntry<ELFT>(in.plt, in.gotPlt, in.relaPlt, target->pltRel, sym); + + // Create a GOT slot if a relocation needs GOT. + if (needsGot(expr)) { + if (config->emachine == EM_MIPS) { + // MIPS ABI has special rules to process GOT entries and doesn't + // require relocation entries for them. A special case is TLS + // relocations. In that case dynamic loader applies dynamic + // relocations to initialize TLS GOT entries. + // See "Global Offset Table" in Chapter 5 in the following document + // for detailed description: + // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf + in.mipsGot->addEntry(*sec.file, sym, addend, expr); + } else if (!sym.isInGot()) { + addGotEntry(sym); + } + } + } else { + // Handle a reference to a non-preemptible ifunc. These are special in a + // few ways: + // + // - Unlike most non-preemptible symbols, non-preemptible ifuncs do not have + // a fixed value. But assuming that all references to the ifunc are + // GOT-generating or PLT-generating, the handling of an ifunc is + // relatively straightforward. We create a PLT entry in Iplt, which is + // usually at the end of .plt, which makes an indirect call using a + // matching GOT entry in igotPlt, which is usually at the end of .got.plt. + // The GOT entry is relocated using an IRELATIVE relocation in relaIplt, + // which is usually at the end of .rela.plt. Unlike most relocations in + // .rela.plt, which may be evaluated lazily without -z now, dynamic + // loaders evaluate IRELATIVE relocs eagerly, which means that for + // IRELATIVE relocs only, GOT-generating relocations can point directly to + // .got.plt without requiring a separate GOT entry. + // + // - Despite the fact that an ifunc does not have a fixed value, compilers + // that are not passed -fPIC will assume that they do, and will emit + // direct (non-GOT-generating, non-PLT-generating) relocations to the + // symbol. This means that if a direct relocation to the symbol is + // seen, the linker must set a value for the symbol, and this value must + // be consistent no matter what type of reference is made to the symbol. + // This can be done by creating a PLT entry for the symbol in the way + // described above and making it canonical, that is, making all references + // point to the PLT entry instead of the resolver. In lld we also store + // the address of the PLT entry in the dynamic symbol table, which means + // that the symbol will also have the same value in other modules. + // Because the value loaded from the GOT needs to be consistent with + // the value computed using a direct relocation, a non-preemptible ifunc + // may end up with two GOT entries, one in .got.plt that points to the + // address returned by the resolver and is used only by the PLT entry, + // and another in .got that points to the PLT entry and is used by + // GOT-generating relocations. + // + // - The fact that these symbols do not have a fixed value makes them an + // exception to the general rule that a statically linked executable does + // not require any form of dynamic relocation. To handle these relocations + // correctly, the IRELATIVE relocations are stored in an array which a + // statically linked executable's startup code must enumerate using the + // linker-defined symbols __rela?_iplt_{start,end}. + // + // - An absolute relocation to a non-preemptible ifunc (such as a global + // variable containing a pointer to the ifunc) needs to be relocated in + // the exact same way as a GOT entry, so we can avoid needing to make the + // PLT entry canonical by translating such relocations into IRELATIVE + // relocations in the relaIplt. + if (!sym.isInPlt()) { + // Create PLT and GOTPLT slots for the symbol. + sym.isInIplt = true; + + // Create a copy of the symbol to use as the target of the IRELATIVE + // relocation in the igotPlt. This is in case we make the PLT canonical + // later, which would overwrite the original symbol. + // + // FIXME: Creating a copy of the symbol here is a bit of a hack. All + // that's really needed to create the IRELATIVE is the section and value, + // so ideally we should just need to copy those. + auto *directSym = make<Defined>(cast<Defined>(sym)); + addPltEntry<ELFT>(in.iplt, in.igotPlt, in.relaIplt, target->iRelativeRel, + *directSym); + sym.pltIndex = directSym->pltIndex; + } + if (expr == R_ABS && addend == 0 && (sec.flags & SHF_WRITE)) { + // We might be able to represent this as an IRELATIVE. But we don't know + // yet whether some later relocation will make the symbol point to a + // canonical PLT, which would make this either a dynamic RELATIVE (PIC) or + // static (non-PIC) relocation. So we keep a record of the information + // required to process the relocation, and after scanRelocs() has been + // called on all relocations, the relocation is resolved by + // addIRelativeRelocs(). + iRelativeRelocs.push_back({type, &sec, offset, &sym}); + return; + } + if (needsGot(expr)) { + // Redirect GOT accesses to point to the Igot. + // + // This field is also used to keep track of whether we ever needed a GOT + // entry. If we did and we make the PLT canonical later, we'll need to + // create a GOT entry pointing to the PLT entry for Sym. + sym.gotInIgot = true; + } else if (!needsPlt(expr)) { + // Make the ifunc's PLT entry canonical by changing the value of its + // symbol to redirect all references to point to it. + unsigned entryOffset = sym.pltIndex * target->pltEntrySize; + if (config->zRetpolineplt) + entryOffset += target->pltHeaderSize; + + auto &d = cast<Defined>(sym); + d.section = in.iplt; + d.value = entryOffset; + d.size = 0; + // It's important to set the symbol type here so that dynamic loaders + // don't try to call the PLT as if it were an ifunc resolver. + d.type = STT_FUNC; + + if (sym.gotInIgot) { + // We previously encountered a GOT generating reference that we + // redirected to the Igot. Now that the PLT entry is canonical we must + // clear the redirection to the Igot and add a GOT entry. As we've + // changed the symbol type to STT_FUNC future GOT generating references + // will naturally use this GOT entry. + // + // We don't need to worry about creating a MIPS GOT here because ifuncs + // aren't a thing on MIPS. + sym.gotInIgot = false; + addGotEntry(sym); + } } } - processRelocAux<ELFT>(Sec, Expr, Type, Offset, Sym, Rel, Addend); + processRelocAux<ELFT>(sec, expr, type, offset, sym, rel, addend); } template <class ELFT, class RelTy> -static void scanRelocs(InputSectionBase &Sec, ArrayRef<RelTy> Rels) { - OffsetGetter GetOffset(Sec); +static void scanRelocs(InputSectionBase &sec, ArrayRef<RelTy> rels) { + OffsetGetter getOffset(sec); // Not all relocations end up in Sec.Relocations, but a lot do. - Sec.Relocations.reserve(Rels.size()); - - for (auto I = Rels.begin(), End = Rels.end(); I != End;) - scanReloc<ELFT>(Sec, GetOffset, I, End); - - // Sort relocations by offset to binary search for R_RISCV_PCREL_HI20 - if (Config->EMachine == EM_RISCV) - std::stable_sort(Sec.Relocations.begin(), Sec.Relocations.end(), - RelocationOffsetComparator{}); + sec.relocations.reserve(rels.size()); + + for (auto i = rels.begin(), end = rels.end(); i != end;) + scanReloc<ELFT>(sec, getOffset, i, end); + + // Sort relocations by offset for more efficient searching for + // R_RISCV_PCREL_HI20 and R_PPC64_ADDR64. + if (config->emachine == EM_RISCV || + (config->emachine == EM_PPC64 && sec.name == ".toc")) + llvm::stable_sort(sec.relocations, + [](const Relocation &lhs, const Relocation &rhs) { + return lhs.offset < rhs.offset; + }); } -template <class ELFT> void elf::scanRelocations(InputSectionBase &S) { - if (S.AreRelocsRela) - scanRelocs<ELFT>(S, S.relas<ELFT>()); +template <class ELFT> void elf::scanRelocations(InputSectionBase &s) { + if (s.areRelocsRela) + scanRelocs<ELFT>(s, s.relas<ELFT>()); else - scanRelocs<ELFT>(S, S.rels<ELFT>()); + scanRelocs<ELFT>(s, s.rels<ELFT>()); +} + +// Figure out which representation to use for any absolute relocs to +// non-preemptible ifuncs that we visited during scanRelocs(). +void elf::addIRelativeRelocs() { + for (IRelativeReloc &r : iRelativeRelocs) { + if (r.sym->type == STT_GNU_IFUNC) + in.relaIplt->addReloc( + {target->iRelativeRel, r.sec, r.offset, true, r.sym, 0}); + else if (config->isPic) + addRelativeReloc(r.sec, r.offset, r.sym, 0, R_ABS, r.type); + else + r.sec->relocations.push_back({R_ABS, r.type, r.offset, 0, r.sym}); + } + iRelativeRelocs.clear(); } -static bool mergeCmp(const InputSection *A, const InputSection *B) { +static bool mergeCmp(const InputSection *a, const InputSection *b) { // std::merge requires a strict weak ordering. - if (A->OutSecOff < B->OutSecOff) + if (a->outSecOff < b->outSecOff) return true; - if (A->OutSecOff == B->OutSecOff) { - auto *TA = dyn_cast<ThunkSection>(A); - auto *TB = dyn_cast<ThunkSection>(B); + if (a->outSecOff == b->outSecOff) { + auto *ta = dyn_cast<ThunkSection>(a); + auto *tb = dyn_cast<ThunkSection>(b); // Check if Thunk is immediately before any specific Target // InputSection for example Mips LA25 Thunks. - if (TA && TA->getTargetInputSection() == B) + if (ta && ta->getTargetInputSection() == b) return true; // Place Thunk Sections without specific targets before // non-Thunk Sections. - if (TA && !TB && !TA->getTargetInputSection()) + if (ta && !tb && !ta->getTargetInputSection()) return true; } @@ -1123,14 +1410,14 @@ static bool mergeCmp(const InputSection *A, const InputSection *B) { // Call Fn on every executable InputSection accessed via the linker script // InputSectionDescription::Sections. static void forEachInputSectionDescription( - ArrayRef<OutputSection *> OutputSections, - llvm::function_ref<void(OutputSection *, InputSectionDescription *)> Fn) { - for (OutputSection *OS : OutputSections) { - if (!(OS->Flags & SHF_ALLOC) || !(OS->Flags & SHF_EXECINSTR)) + ArrayRef<OutputSection *> outputSections, + llvm::function_ref<void(OutputSection *, InputSectionDescription *)> fn) { + for (OutputSection *os : outputSections) { + if (!(os->flags & SHF_ALLOC) || !(os->flags & SHF_EXECINSTR)) continue; - for (BaseCommand *BC : OS->SectionCommands) - if (auto *ISD = dyn_cast<InputSectionDescription>(BC)) - Fn(OS, ISD); + for (BaseCommand *bc : os->sectionCommands) + if (auto *isd = dyn_cast<InputSectionDescription>(bc)) + fn(os, isd); } } @@ -1225,54 +1512,54 @@ static void forEachInputSectionDescription( // in the Sections vector, and recalculate the InputSection output section // offsets. // This may invalidate any output section offsets stored outside of InputSection -void ThunkCreator::mergeThunks(ArrayRef<OutputSection *> OutputSections) { +void ThunkCreator::mergeThunks(ArrayRef<OutputSection *> outputSections) { forEachInputSectionDescription( - OutputSections, [&](OutputSection *OS, InputSectionDescription *ISD) { - if (ISD->ThunkSections.empty()) + outputSections, [&](OutputSection *os, InputSectionDescription *isd) { + if (isd->thunkSections.empty()) return; // Remove any zero sized precreated Thunks. - llvm::erase_if(ISD->ThunkSections, - [](const std::pair<ThunkSection *, uint32_t> &TS) { - return TS.first->getSize() == 0; + llvm::erase_if(isd->thunkSections, + [](const std::pair<ThunkSection *, uint32_t> &ts) { + return ts.first->getSize() == 0; }); // ISD->ThunkSections contains all created ThunkSections, including // those inserted in previous passes. Extract the Thunks created this - // pass and order them in ascending OutSecOff. - std::vector<ThunkSection *> NewThunks; - for (const std::pair<ThunkSection *, uint32_t> TS : ISD->ThunkSections) - if (TS.second == Pass) - NewThunks.push_back(TS.first); - std::stable_sort(NewThunks.begin(), NewThunks.end(), - [](const ThunkSection *A, const ThunkSection *B) { - return A->OutSecOff < B->OutSecOff; - }); - - // Merge sorted vectors of Thunks and InputSections by OutSecOff - std::vector<InputSection *> Tmp; - Tmp.reserve(ISD->Sections.size() + NewThunks.size()); - - std::merge(ISD->Sections.begin(), ISD->Sections.end(), - NewThunks.begin(), NewThunks.end(), std::back_inserter(Tmp), + // pass and order them in ascending outSecOff. + std::vector<ThunkSection *> newThunks; + for (const std::pair<ThunkSection *, uint32_t> ts : isd->thunkSections) + if (ts.second == pass) + newThunks.push_back(ts.first); + llvm::stable_sort(newThunks, + [](const ThunkSection *a, const ThunkSection *b) { + return a->outSecOff < b->outSecOff; + }); + + // Merge sorted vectors of Thunks and InputSections by outSecOff + std::vector<InputSection *> tmp; + tmp.reserve(isd->sections.size() + newThunks.size()); + + std::merge(isd->sections.begin(), isd->sections.end(), + newThunks.begin(), newThunks.end(), std::back_inserter(tmp), mergeCmp); - ISD->Sections = std::move(Tmp); + isd->sections = std::move(tmp); }); } // Find or create a ThunkSection within the InputSectionDescription (ISD) that // is in range of Src. An ISD maps to a range of InputSections described by a // linker script section pattern such as { .text .text.* }. -ThunkSection *ThunkCreator::getISDThunkSec(OutputSection *OS, InputSection *IS, - InputSectionDescription *ISD, - uint32_t Type, uint64_t Src) { - for (std::pair<ThunkSection *, uint32_t> TP : ISD->ThunkSections) { - ThunkSection *TS = TP.first; - uint64_t TSBase = OS->Addr + TS->OutSecOff; - uint64_t TSLimit = TSBase + TS->getSize(); - if (Target->inBranchRange(Type, Src, (Src > TSLimit) ? TSBase : TSLimit)) - return TS; +ThunkSection *ThunkCreator::getISDThunkSec(OutputSection *os, InputSection *isec, + InputSectionDescription *isd, + uint32_t type, uint64_t src) { + for (std::pair<ThunkSection *, uint32_t> tp : isd->thunkSections) { + ThunkSection *ts = tp.first; + uint64_t tsBase = os->addr + ts->outSecOff; + uint64_t tsLimit = tsBase + ts->getSize(); + if (target->inBranchRange(type, src, (src > tsLimit) ? tsBase : tsLimit)) + return ts; } // No suitable ThunkSection exists. This can happen when there is a branch @@ -1280,40 +1567,40 @@ ThunkSection *ThunkCreator::getISDThunkSec(OutputSection *OS, InputSection *IS, // many Thunks. Create a new ThunkSection as close to the InputSection as // possible. Error if InputSection is so large we cannot place ThunkSection // anywhere in Range. - uint64_t ThunkSecOff = IS->OutSecOff; - if (!Target->inBranchRange(Type, Src, OS->Addr + ThunkSecOff)) { - ThunkSecOff = IS->OutSecOff + IS->getSize(); - if (!Target->inBranchRange(Type, Src, OS->Addr + ThunkSecOff)) + uint64_t thunkSecOff = isec->outSecOff; + if (!target->inBranchRange(type, src, os->addr + thunkSecOff)) { + thunkSecOff = isec->outSecOff + isec->getSize(); + if (!target->inBranchRange(type, src, os->addr + thunkSecOff)) fatal("InputSection too large for range extension thunk " + - IS->getObjMsg(Src - (OS->Addr + IS->OutSecOff))); + isec->getObjMsg(src - (os->addr + isec->outSecOff))); } - return addThunkSection(OS, ISD, ThunkSecOff); + return addThunkSection(os, isd, thunkSecOff); } // Add a Thunk that needs to be placed in a ThunkSection that immediately // precedes its Target. -ThunkSection *ThunkCreator::getISThunkSec(InputSection *IS) { - ThunkSection *TS = ThunkedSections.lookup(IS); - if (TS) - return TS; +ThunkSection *ThunkCreator::getISThunkSec(InputSection *isec) { + ThunkSection *ts = thunkedSections.lookup(isec); + if (ts) + return ts; // Find InputSectionRange within Target Output Section (TOS) that the // InputSection (IS) that we need to precede is in. - OutputSection *TOS = IS->getParent(); - for (BaseCommand *BC : TOS->SectionCommands) { - auto *ISD = dyn_cast<InputSectionDescription>(BC); - if (!ISD || ISD->Sections.empty()) + OutputSection *tos = isec->getParent(); + for (BaseCommand *bc : tos->sectionCommands) { + auto *isd = dyn_cast<InputSectionDescription>(bc); + if (!isd || isd->sections.empty()) continue; - InputSection *First = ISD->Sections.front(); - InputSection *Last = ISD->Sections.back(); + InputSection *first = isd->sections.front(); + InputSection *last = isd->sections.back(); - if (IS->OutSecOff < First->OutSecOff || Last->OutSecOff < IS->OutSecOff) + if (isec->outSecOff < first->outSecOff || last->outSecOff < isec->outSecOff) continue; - TS = addThunkSection(TOS, ISD, IS->OutSecOff); - ThunkedSections[IS] = TS; - return TS; + ts = addThunkSection(tos, isd, isec->outSecOff); + thunkedSections[isec] = ts; + return ts; } return nullptr; @@ -1336,82 +1623,93 @@ ThunkSection *ThunkCreator::getISThunkSec(InputSection *IS) { // distance from a thunk to its target will be sufficiently small to // allow for the creation of a short thunk. void ThunkCreator::createInitialThunkSections( - ArrayRef<OutputSection *> OutputSections) { - uint32_t ThunkSectionSpacing = Target->getThunkSectionSpacing(); + ArrayRef<OutputSection *> outputSections) { + uint32_t thunkSectionSpacing = target->getThunkSectionSpacing(); forEachInputSectionDescription( - OutputSections, [&](OutputSection *OS, InputSectionDescription *ISD) { - if (ISD->Sections.empty()) + outputSections, [&](OutputSection *os, InputSectionDescription *isd) { + if (isd->sections.empty()) return; - uint32_t ISDBegin = ISD->Sections.front()->OutSecOff; - uint32_t ISDEnd = - ISD->Sections.back()->OutSecOff + ISD->Sections.back()->getSize(); - uint32_t LastThunkLowerBound = -1; - if (ISDEnd - ISDBegin > ThunkSectionSpacing * 2) - LastThunkLowerBound = ISDEnd - ThunkSectionSpacing; - - uint32_t ISLimit; - uint32_t PrevISLimit = ISDBegin; - uint32_t ThunkUpperBound = ISDBegin + ThunkSectionSpacing; - - for (const InputSection *IS : ISD->Sections) { - ISLimit = IS->OutSecOff + IS->getSize(); - if (ISLimit > ThunkUpperBound) { - addThunkSection(OS, ISD, PrevISLimit); - ThunkUpperBound = PrevISLimit + ThunkSectionSpacing; + uint32_t isdBegin = isd->sections.front()->outSecOff; + uint32_t isdEnd = + isd->sections.back()->outSecOff + isd->sections.back()->getSize(); + uint32_t lastThunkLowerBound = -1; + if (isdEnd - isdBegin > thunkSectionSpacing * 2) + lastThunkLowerBound = isdEnd - thunkSectionSpacing; + + uint32_t isecLimit; + uint32_t prevIsecLimit = isdBegin; + uint32_t thunkUpperBound = isdBegin + thunkSectionSpacing; + + for (const InputSection *isec : isd->sections) { + isecLimit = isec->outSecOff + isec->getSize(); + if (isecLimit > thunkUpperBound) { + addThunkSection(os, isd, prevIsecLimit); + thunkUpperBound = prevIsecLimit + thunkSectionSpacing; } - if (ISLimit > LastThunkLowerBound) + if (isecLimit > lastThunkLowerBound) break; - PrevISLimit = ISLimit; + prevIsecLimit = isecLimit; } - addThunkSection(OS, ISD, ISLimit); + addThunkSection(os, isd, isecLimit); }); } -ThunkSection *ThunkCreator::addThunkSection(OutputSection *OS, - InputSectionDescription *ISD, - uint64_t Off) { - auto *TS = make<ThunkSection>(OS, Off); - ISD->ThunkSections.push_back({TS, Pass}); - return TS; +ThunkSection *ThunkCreator::addThunkSection(OutputSection *os, + InputSectionDescription *isd, + uint64_t off) { + auto *ts = make<ThunkSection>(os, off); + ts->partition = os->partition; + isd->thunkSections.push_back({ts, pass}); + return ts; } -std::pair<Thunk *, bool> ThunkCreator::getThunk(Symbol &Sym, RelType Type, - uint64_t Src) { - std::vector<Thunk *> *ThunkVec = nullptr; +static bool isThunkSectionCompatible(InputSection *source, + SectionBase *target) { + // We can't reuse thunks in different loadable partitions because they might + // not be loaded. But partition 1 (the main partition) will always be loaded. + if (source->partition != target->partition) + return target->partition == 1; + return true; +} + +std::pair<Thunk *, bool> ThunkCreator::getThunk(InputSection *isec, + Relocation &rel, uint64_t src) { + std::vector<Thunk *> *thunkVec = nullptr; // We use (section, offset) pair to find the thunk position if possible so // that we create only one thunk for aliased symbols or ICFed sections. - if (auto *D = dyn_cast<Defined>(&Sym)) - if (!D->isInPlt() && D->Section) - ThunkVec = &ThunkedSymbolsBySection[{D->Section->Repl, D->Value}]; - if (!ThunkVec) - ThunkVec = &ThunkedSymbols[&Sym]; + if (auto *d = dyn_cast<Defined>(rel.sym)) + if (!d->isInPlt() && d->section) + thunkVec = &thunkedSymbolsBySection[{d->section->repl, d->value}]; + if (!thunkVec) + thunkVec = &thunkedSymbols[rel.sym]; // Check existing Thunks for Sym to see if they can be reused - for (Thunk *T : *ThunkVec) - if (T->isCompatibleWith(Type) && - Target->inBranchRange(Type, Src, T->getThunkTargetSym()->getVA())) - return std::make_pair(T, false); + for (Thunk *t : *thunkVec) + if (isThunkSectionCompatible(isec, t->getThunkTargetSym()->section) && + t->isCompatibleWith(*isec, rel) && + target->inBranchRange(rel.type, src, t->getThunkTargetSym()->getVA())) + return std::make_pair(t, false); // No existing compatible Thunk in range, create a new one - Thunk *T = addThunk(Type, Sym); - ThunkVec->push_back(T); - return std::make_pair(T, true); + Thunk *t = addThunk(*isec, rel); + thunkVec->push_back(t); + return std::make_pair(t, true); } // Return true if the relocation target is an in range Thunk. // Return false if the relocation is not to a Thunk. If the relocation target // was originally to a Thunk, but is no longer in range we revert the // relocation back to its original non-Thunk target. -bool ThunkCreator::normalizeExistingThunk(Relocation &Rel, uint64_t Src) { - if (Thunk *T = Thunks.lookup(Rel.Sym)) { - if (Target->inBranchRange(Rel.Type, Src, Rel.Sym->getVA())) +bool ThunkCreator::normalizeExistingThunk(Relocation &rel, uint64_t src) { + if (Thunk *t = thunks.lookup(rel.sym)) { + if (target->inBranchRange(rel.type, src, rel.sym->getVA())) return true; - Rel.Sym = &T->Destination; - if (Rel.Sym->isInPlt()) - Rel.Expr = toPlt(Rel.Expr); + rel.sym = &t->destination; + if (rel.sym->isInPlt()) + rel.expr = toPlt(rel.expr); } return false; } @@ -1441,15 +1739,15 @@ bool ThunkCreator::normalizeExistingThunk(Relocation &Rel, uint64_t Src) { // made no changes. If the target requires range extension thunks, currently // ARM, then any future change in offset between caller and callee risks a // relocation out of range error. -bool ThunkCreator::createThunks(ArrayRef<OutputSection *> OutputSections) { - bool AddressesChanged = false; +bool ThunkCreator::createThunks(ArrayRef<OutputSection *> outputSections) { + bool addressesChanged = false; - if (Pass == 0 && Target->getThunkSectionSpacing()) - createInitialThunkSections(OutputSections); + if (pass == 0 && target->getThunkSectionSpacing()) + createInitialThunkSections(outputSections); // With Thunk Size much smaller than branch range we expect to // converge quickly; if we get to 10 something has gone wrong. - if (Pass == 10) + if (pass == 10) fatal("thunk creation not converged"); // Create all the Thunks and insert them into synthetic ThunkSections. The @@ -1458,55 +1756,64 @@ bool ThunkCreator::createThunks(ArrayRef<OutputSection *> OutputSections) { // ThunkSections as ThunkSections are not always inserted into the same // InputSectionDescription as the caller. forEachInputSectionDescription( - OutputSections, [&](OutputSection *OS, InputSectionDescription *ISD) { - for (InputSection *IS : ISD->Sections) - for (Relocation &Rel : IS->Relocations) { - uint64_t Src = IS->getVA(Rel.Offset); + outputSections, [&](OutputSection *os, InputSectionDescription *isd) { + for (InputSection *isec : isd->sections) + for (Relocation &rel : isec->relocations) { + uint64_t src = isec->getVA(rel.offset); // If we are a relocation to an existing Thunk, check if it is // still in range. If not then Rel will be altered to point to its // original target so another Thunk can be generated. - if (Pass > 0 && normalizeExistingThunk(Rel, Src)) + if (pass > 0 && normalizeExistingThunk(rel, src)) continue; - if (!Target->needsThunk(Rel.Expr, Rel.Type, IS->File, Src, - *Rel.Sym)) + if (!target->needsThunk(rel.expr, rel.type, isec->file, src, + *rel.sym)) continue; - Thunk *T; - bool IsNew; - std::tie(T, IsNew) = getThunk(*Rel.Sym, Rel.Type, Src); + Thunk *t; + bool isNew; + std::tie(t, isNew) = getThunk(isec, rel, src); - if (IsNew) { + if (isNew) { // Find or create a ThunkSection for the new Thunk - ThunkSection *TS; - if (auto *TIS = T->getTargetInputSection()) - TS = getISThunkSec(TIS); + ThunkSection *ts; + if (auto *tis = t->getTargetInputSection()) + ts = getISThunkSec(tis); else - TS = getISDThunkSec(OS, IS, ISD, Rel.Type, Src); - TS->addThunk(T); - Thunks[T->getThunkTargetSym()] = T; + ts = getISDThunkSec(os, isec, isd, rel.type, src); + ts->addThunk(t); + thunks[t->getThunkTargetSym()] = t; } // Redirect relocation to Thunk, we never go via the PLT to a Thunk - Rel.Sym = T->getThunkTargetSym(); - Rel.Expr = fromPlt(Rel.Expr); + rel.sym = t->getThunkTargetSym(); + rel.expr = fromPlt(rel.expr); + + // The addend of R_PPC_PLTREL24 should be ignored after changing to + // R_PC. + if (config->emachine == EM_PPC && rel.type == R_PPC_PLTREL24) + rel.addend = 0; } - for (auto &P : ISD->ThunkSections) - AddressesChanged |= P.first->assignOffsets(); + for (auto &p : isd->thunkSections) + addressesChanged |= p.first->assignOffsets(); }); - for (auto &P : ThunkedSections) - AddressesChanged |= P.second->assignOffsets(); + for (auto &p : thunkedSections) + addressesChanged |= p.second->assignOffsets(); // Merge all created synthetic ThunkSections back into OutputSection - mergeThunks(OutputSections); - ++Pass; - return AddressesChanged; + mergeThunks(outputSections); + ++pass; + return addressesChanged; } template void elf::scanRelocations<ELF32LE>(InputSectionBase &); template void elf::scanRelocations<ELF32BE>(InputSectionBase &); template void elf::scanRelocations<ELF64LE>(InputSectionBase &); template void elf::scanRelocations<ELF64BE>(InputSectionBase &); +template void elf::reportUndefinedSymbols<ELF32LE>(); +template void elf::reportUndefinedSymbols<ELF32BE>(); +template void elf::reportUndefinedSymbols<ELF64LE>(); +template void elf::reportUndefinedSymbols<ELF64BE>(); |