[lld] r353981 - ELF: Allow GOT relocs pointing to non-preemptable ifunc to resolve to an IRELATIVE where possible.
Peter Collingbourne via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 13 13:49:55 PST 2019
Author: pcc
Date: Wed Feb 13 13:49:55 2019
New Revision: 353981
URL: http://llvm.org/viewvc/llvm-project?rev=353981&view=rev
Log:
ELF: Allow GOT relocs pointing to non-preemptable ifunc to resolve to an IRELATIVE where possible.
Non-GOT non-PLT relocations to non-preemptible ifuncs result in the
creation of a canonical PLT, which now takes the identity of the IFUNC
in the symbol table. This (a) ensures address consistency inside and
outside the module, and (b) fixes a bug where some of these relocations
end up pointing to the resolver.
Fixes (at least) PR40474 and PR40501.
Differential Revision: https://reviews.llvm.org/D57371
Added:
lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-abs.s
lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-pcrel.s
lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-rw-addend.s
lld/trunk/test/ELF/gnu-ifunc-canon.s
Modified:
lld/trunk/ELF/InputSection.cpp
lld/trunk/ELF/Relocations.cpp
lld/trunk/ELF/Relocations.h
lld/trunk/ELF/Symbols.cpp
lld/trunk/ELF/Symbols.h
lld/trunk/ELF/SyntheticSections.cpp
lld/trunk/ELF/Writer.cpp
lld/trunk/test/ELF/aarch64-gnu-ifunc-address-pie.s
lld/trunk/test/ELF/aarch64-gnu-ifunc-address.s
lld/trunk/test/ELF/aarch64-gnu-ifunc2.s
lld/trunk/test/ELF/aarch64-gnu-ifunc3.s
lld/trunk/test/ELF/gnu-ifunc-i386.s
Modified: lld/trunk/ELF/InputSection.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputSection.cpp?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/ELF/InputSection.cpp (original)
+++ lld/trunk/ELF/InputSection.cpp Wed Feb 13 13:49:55 2019
@@ -611,7 +611,6 @@ static uint64_t getRelocTargetVA(const I
case R_ARM_SBREL:
return Sym.getVA(A) - getARMStaticBase(Sym);
case R_GOT:
- case R_GOT_PLT:
case R_RELAX_TLS_GD_TO_IE_ABS:
return Sym.getGotVA() + A;
case R_GOTONLY_PC:
@@ -630,7 +629,6 @@ static uint64_t getRelocTargetVA(const I
case R_RELAX_TLS_GD_TO_IE_GOT_OFF:
return Sym.getGotOffset() + A;
case R_AARCH64_GOT_PAGE_PC:
- case R_AARCH64_GOT_PAGE_PC_PLT:
case R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC:
return getAArch64Page(Sym.getGotVA() + A) - getAArch64Page(P);
case R_GOT_PC:
@@ -680,10 +678,6 @@ static uint64_t getRelocTargetVA(const I
uint64_t Val = Sym.isUndefWeak() ? P + A : Sym.getVA(A);
return getAArch64Page(Val) - getAArch64Page(P);
}
- case R_AARCH64_PLT_PAGE_PC: {
- uint64_t Val = Sym.isUndefWeak() ? P + A : Sym.getPltVA() + A;
- return getAArch64Page(Val) - getAArch64Page(P);
- }
case R_RISCV_PC_INDIRECT: {
if (const Relocation *HiRel = getRISCVPCRelHi20(&Sym, A))
return getRelocTargetVA(File, HiRel->Type, HiRel->Addend, Sym.getVA(),
Modified: lld/trunk/ELF/Relocations.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.cpp?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.cpp (original)
+++ lld/trunk/ELF/Relocations.cpp Wed Feb 13 13:49:55 2019
@@ -336,8 +336,7 @@ static bool isAbsoluteValue(const Symbol
// 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);
+ return isRelExprOneOf<R_PLT_PC, R_PPC_CALL_PLT, R_PLT>(Expr);
}
// Returns true if Expr refers a GOT entry. Note that this function
@@ -346,8 +345,7 @@ static bool needsPlt(RelExpr Expr) {
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);
+ R_GOT_PC, R_GOT_FROM_END>(Expr);
}
// True if this expression is of the form Sym - X, where X is a position in the
@@ -355,7 +353,7 @@ static bool needsGot(RelExpr Expr) {
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_AARCH64_PLT_PAGE_PC, R_RELAX_GOT_PC>(Expr);
+ R_RELAX_GOT_PC>(Expr);
}
// Returns true if a given relocation can be computed at link-time.
@@ -373,8 +371,8 @@ static bool isStaticLinkTimeConstant(Rel
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_AARCH64_GOT_PAGE_PC, 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))
@@ -382,7 +380,7 @@ static bool isStaticLinkTimeConstant(Rel
// 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)
+ if (E == R_GOT || E == R_PLT || E == R_TLSDESC)
return Target->usesOnlyLowPageBits(Type) || !Config->Pic;
if (Sym.IsPreemptible)
@@ -428,14 +426,8 @@ static RelExpr toPlt(RelExpr Expr) {
return R_PPC_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;
}
@@ -767,14 +759,7 @@ static void addPltEntry(PltSection *Plt,
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;
-
+ 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,
@@ -969,6 +954,15 @@ static void processRelocAux(InputSection
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) {
@@ -1011,32 +1005,29 @@ static void scanReloc(InputSectionBase &
if (Config->EMachine == EM_PPC64 && isPPC64SmallCodeModelTocReloc(Type))
Sec.File->PPC64SmallCodeModelTocRelocs = true;
- // Strengthen or relax relocations.
- //
- // GNU ifunc symbols must be accessed via PLT because their addresses
- // are determined by runtime.
+ 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));
+ }
+
+ // 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));
- }
- 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);
+ // 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()) {
+ if (Expr == R_GOT_PC && !isAbsoluteValue(Sym))
+ Expr = Target->adjustRelaxExpr(Type, RelocatedAddr, Expr);
+ else
+ Expr = fromPlt(Expr);
}
// This relocation does not require got entry, but it is relative to got and
@@ -1056,28 +1047,136 @@ static void scanReloc(InputSectionBase &
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
+ // 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<ELFT>(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<ELFT>(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<ELFT>(Sym);
+ }
}
}
@@ -1107,6 +1206,21 @@ template <class ELFT> void elf::scanRelo
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->Pic)
+ 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) {
// std::merge requires a strict weak ordering.
if (A->OutSecOff < B->OutSecOff)
Modified: lld/trunk/ELF/Relocations.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Relocations.h?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/ELF/Relocations.h (original)
+++ lld/trunk/ELF/Relocations.h Wed Feb 13 13:49:55 2019
@@ -33,19 +33,11 @@ enum RelExpr {
R_ABS,
R_ADDEND,
R_AARCH64_GOT_PAGE_PC,
- // The expression is used for IFUNC support. Describes PC-relative
- // address of the memory page of GOT entry. This entry is used for
- // a redirection to IPLT.
- R_AARCH64_GOT_PAGE_PC_PLT,
R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC,
R_AARCH64_PAGE_PC,
- R_AARCH64_PLT_PAGE_PC,
R_AARCH64_TLSDESC_PAGE,
R_ARM_SBREL,
R_GOT,
- // The expression is used for IFUNC support. Evaluates to GOT entry,
- // containing redirection to the IPLT.
- R_GOT_PLT,
R_GOTONLY_PC,
R_GOTONLY_PC_FROM_END,
R_GOTREL,
@@ -154,6 +146,8 @@ struct RelocationOffsetComparator {
template <class ELFT> void scanRelocations(InputSectionBase &);
+void addIRelativeRelocs();
+
class ThunkSection;
class Thunk;
struct InputSectionDescription;
Modified: lld/trunk/ELF/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.cpp?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.cpp (original)
+++ lld/trunk/ELF/Symbols.cpp Wed Feb 13 13:49:55 2019
@@ -120,20 +120,24 @@ uint64_t Symbol::getVA(int64_t Addend) c
return OutVA + Addend;
}
-uint64_t Symbol::getGotVA() const { return In.Got->getVA() + getGotOffset(); }
+uint64_t Symbol::getGotVA() const {
+ if (GotInIgot)
+ return In.IgotPlt->getVA() + getGotPltOffset();
+ return In.Got->getVA() + getGotOffset();
+}
uint64_t Symbol::getGotOffset() const {
return GotIndex * Target->GotEntrySize;
}
uint64_t Symbol::getGotPltVA() const {
- if (this->IsInIgot)
+ if (IsInIplt)
return In.IgotPlt->getVA() + getGotPltOffset();
return In.GotPlt->getVA() + getGotPltOffset();
}
uint64_t Symbol::getGotPltOffset() const {
- if (IsInIgot)
+ if (IsInIplt)
return PltIndex * Target->GotPltEntrySize;
return (PltIndex + Target->GotPltHeaderEntriesNum) * Target->GotPltEntrySize;
}
Modified: lld/trunk/ELF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.h?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.h (original)
+++ lld/trunk/ELF/Symbols.h Wed Feb 13 13:49:55 2019
@@ -181,7 +181,7 @@ protected:
uint8_t StOther, uint8_t Type)
: File(File), NameData(Name.Data), NameSize(Name.Size), Binding(Binding),
Type(Type), StOther(StOther), SymbolKind(K), NeedsPltAddr(false),
- IsInIplt(false), IsInIgot(false), IsPreemptible(false),
+ IsInIplt(false), GotInIgot(false), IsPreemptible(false),
Used(!Config->GcSections), NeedsTocRestore(false),
ScriptDefined(false) {}
@@ -190,11 +190,13 @@ public:
// For SharedSymbol only.
unsigned NeedsPltAddr : 1;
- // True if this symbol is in the Iplt sub-section of the Plt.
+ // True if this symbol is in the Iplt sub-section of the Plt and the Igot
+ // sub-section of the .got.plt or .got.
unsigned IsInIplt : 1;
- // True if this symbol is in the Igot sub-section of the .got.plt or .got.
- unsigned IsInIgot : 1;
+ // True if this symbol needs a GOT entry and its GOT entry is actually in
+ // Igot. This will be true only for certain non-preemptible ifuncs.
+ unsigned GotInIgot : 1;
// True if this symbol is preemptible at load time.
unsigned IsPreemptible : 1;
Modified: lld/trunk/ELF/SyntheticSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.cpp?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.cpp (original)
+++ lld/trunk/ELF/SyntheticSections.cpp Wed Feb 13 13:49:55 2019
@@ -1142,7 +1142,6 @@ IgotPltSection::IgotPltSection()
Target->GotPltEntrySize, getIgotPltName()) {}
void IgotPltSection::addEntry(Symbol &Sym) {
- Sym.IsInIgot = true;
assert(Sym.PltIndex == Entries.size());
Entries.push_back(&Sym);
}
@@ -2344,10 +2343,8 @@ void PltSection::writeTo(uint8_t *Buf) {
template <class ELFT> void PltSection::addEntry(Symbol &Sym) {
Sym.PltIndex = Entries.size();
RelocationBaseSection *PltRelocSection = In.RelaPlt;
- if (IsIplt) {
+ if (IsIplt)
PltRelocSection = In.RelaIplt;
- Sym.IsInIplt = true;
- }
unsigned RelOff =
static_cast<RelocationSection<ELFT> *>(PltRelocSection)->getRelocOffset();
Entries.push_back(std::make_pair(&Sym, RelOff));
Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Wed Feb 13 13:49:55 2019
@@ -1677,6 +1677,8 @@ template <class ELFT> void Writer<ELFT>:
if (!Config->Relocatable)
forEachRelSec(scanRelocations<ELFT>);
+ addIRelativeRelocs();
+
if (In.Plt && !In.Plt->empty())
In.Plt->addSymbols();
if (In.Iplt && !In.Iplt->empty())
Added: lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-abs.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-abs.s?rev=353981&view=auto
==============================================================================
--- lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-abs.s (added)
+++ lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-abs.s Wed Feb 13 13:49:55 2019
@@ -0,0 +1,2 @@
+.rodata
+.8byte ifunc
Added: lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-pcrel.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-pcrel.s?rev=353981&view=auto
==============================================================================
--- lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-pcrel.s (added)
+++ lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-ro-pcrel.s Wed Feb 13 13:49:55 2019
@@ -0,0 +1,2 @@
+.rodata
+.4byte ifunc - .
Added: lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-rw-addend.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-rw-addend.s?rev=353981&view=auto
==============================================================================
--- lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-rw-addend.s (added)
+++ lld/trunk/test/ELF/Inputs/gnu-ifunc-canon-rw-addend.s Wed Feb 13 13:49:55 2019
@@ -0,0 +1,2 @@
+.data
+.8byte ifunc + 1
Modified: lld/trunk/test/ELF/aarch64-gnu-ifunc-address-pie.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/aarch64-gnu-ifunc-address-pie.s?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/test/ELF/aarch64-gnu-ifunc-address-pie.s (original)
+++ lld/trunk/test/ELF/aarch64-gnu-ifunc-address-pie.s Wed Feb 13 13:49:55 2019
@@ -12,6 +12,9 @@
.globl myfunc
.type myfunc, at gnu_indirect_function
myfunc:
+.globl myfunc_resolver
+.type myfunc_resolver, at function
+myfunc_resolver:
ret
.text
@@ -22,7 +25,7 @@ main:
add x8, x8, :lo12: myfunc
ret
-# CHECK: 0000000000010000 myfunc:
+# CHECK: 0000000000010000 myfunc_resolver:
# CHECK-NEXT: 10000: c0 03 5f d6 ret
# CHECK: 0000000000010004 main:
# CHECK-NEXT: 10004: 08 00 00 90 adrp x8, #0
@@ -31,7 +34,7 @@ main:
# x8 = 0x10010 = .plt for myfunc
# CHECK-NEXT: 1000c: c0 03 5f d6 ret
# CHECK-NEXT: Disassembly of section .plt:
-# CHECK-NEXT: 0000000000010010 .plt:
+# CHECK-NEXT: 0000000000010010 myfunc:
# CHECK-NEXT: 10010: 90 00 00 90 adrp x16, #65536
# CHECK-NEXT: 10014: 11 02 40 f9 ldr x17, [x16]
# CHECK-NEXT: 10018: 10 02 00 91 add x16, x16, #0
Modified: lld/trunk/test/ELF/aarch64-gnu-ifunc-address.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/aarch64-gnu-ifunc-address.s?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/test/ELF/aarch64-gnu-ifunc-address.s (original)
+++ lld/trunk/test/ELF/aarch64-gnu-ifunc-address.s Wed Feb 13 13:49:55 2019
@@ -21,20 +21,17 @@ main:
ldr x8, [x8, :got_lo12:myfunc]
ret
# CHECK: 0000000000010004 main:
-# x8 = 0x30000
-# CHECK-NEXT: 10004: 08 01 00 90 adrp x8, #131072
-# x8 = 0x300e0 = .got entry for myfunc with R_AARCH64_GLOB_DAT
-# CHECK-NEXT: 10008: 08 71 40 f9 ldr x8, [x8, #224]
+# x8 = 0x20000
+# CHECK-NEXT: 10004: 88 00 00 90 adrp x8, #65536
+# x8 = 0x200a0 = .got entry for myfunc with R_AARCH64_GLOB_DAT
+# CHECK-NEXT: 10008: 08 51 40 f9 ldr x8, [x8, #160]
# CHECK-NEXT: 1000c: c0 03 5f d6 ret
# CHECK: Disassembly of section .got:
-# CHECK-NEXT: 00000000000300e0 .got:
+# CHECK-NEXT: 00000000000200a0 .got:
# CHECK-RELOCS: Relocations [
# CHECK-RELOCS-NEXT: Section {{.*}} .rela.dyn {
-# CHECK-RELOCS-NEXT: 0x300E0 R_AARCH64_GLOB_DAT myfunc 0x0
-# CHECK-RELOCS-NEXT: }
-# CHECK-RELOCS-NEXT: Section {{.*}} .rela.plt {
-# CHECK-RELOCS-NEXT: 0x20018 R_AARCH64_JUMP_SLOT myfunc 0x0
+# CHECK-RELOCS-NEXT: 0x200A0 R_AARCH64_GLOB_DAT myfunc 0x0
# CHECK-RELOCS-NEXT: }
# CHECK-RELOCS-NEXT: ]
Modified: lld/trunk/test/ELF/aarch64-gnu-ifunc2.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/aarch64-gnu-ifunc2.s?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/test/ELF/aarch64-gnu-ifunc2.s (original)
+++ lld/trunk/test/ELF/aarch64-gnu-ifunc2.s Wed Feb 13 13:49:55 2019
@@ -9,8 +9,8 @@
# CHECK-NEXT: 210000:
# CHECK: main:
-# adrp x8, 0x230000, 0x230000 == address in .got
-# CHECK-NEXT: 210004: {{.*}} adrp x8, #131072
+# adrp x8, 0x220000, 0x220000 == address in .got.plt
+# CHECK-NEXT: 210004: {{.*}} adrp x8, #65536
# CHECK-NEXT: 210008: {{.*}} ldr x8, [x8]
# CHECK-NEXT: 21000c: {{.*}} ret
@@ -26,11 +26,6 @@
# CHECK-NEXT: .got.plt:
# CHECK-NEXT: 220000:
-# CHECK: Disassembly of section .got:
-# CHECK-NEXT: .got:
-# 0x210010 == address in .plt
-# CHECK-NEXT: 230000: 10 00 21 00
-
# RELOC: Relocations [
# RELOC-NEXT: Section {{.*}} .rela.plt {
# RELOC-NEXT: 0x220000 R_AARCH64_IRELATIVE - 0x210000
Modified: lld/trunk/test/ELF/aarch64-gnu-ifunc3.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/aarch64-gnu-ifunc3.s?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/test/ELF/aarch64-gnu-ifunc3.s (original)
+++ lld/trunk/test/ELF/aarch64-gnu-ifunc3.s Wed Feb 13 13:49:55 2019
@@ -11,6 +11,9 @@
.globl myfunc
.type myfunc, at gnu_indirect_function
myfunc:
+.globl myfunc_resolver
+.type myfunc_resolver, at function
+myfunc_resolver:
ret
.text
@@ -22,7 +25,7 @@ _start:
ret
# CHECK: Disassembly of section .text:
-# CHECK-NEXT: myfunc:
+# CHECK-NEXT: myfunc_resolver:
# CHECK-NEXT: 210000: c0 03 5f d6 ret
# CHECK: _start:
# adrp x8, 0x210000 + 0x10 from add == .plt entry
@@ -30,7 +33,7 @@ _start:
# CHECK-NEXT: 210008: 08 41 00 91 add x8, x8, #16
# CHECK-NEXT: 21000c: c0 03 5f d6 ret
# CHECK-NEXT: Disassembly of section .plt:
-# CHECK-NEXT: .plt:
+# CHECK-NEXT: myfunc:
# adrp x16, 0x220000, 0x220000 == address in .got.plt
# CHECK-NEXT: 210010: 90 00 00 90 adrp x16, #65536
# CHECK-NEXT: 210014: 11 02 40 f9 ldr x17, [x16]
Added: lld/trunk/test/ELF/gnu-ifunc-canon.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/gnu-ifunc-canon.s?rev=353981&view=auto
==============================================================================
--- lld/trunk/test/ELF/gnu-ifunc-canon.s (added)
+++ lld/trunk/test/ELF/gnu-ifunc-canon.s Wed Feb 13 13:49:55 2019
@@ -0,0 +1,92 @@
+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/gnu-ifunc-canon-ro-pcrel.s -o %t-ro-pcrel.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/gnu-ifunc-canon-ro-abs.s -o %t-ro-abs.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/gnu-ifunc-canon-rw-addend.s -o %t-rw-addend.o
+// RUN: ld.lld %t.o -o %t1
+// RUN: llvm-readobj -relocs %t1 | FileCheck --check-prefix=IREL2 %s
+// RUN: ld.lld %t.o %t-ro-pcrel.o -o %t2
+// RUN: llvm-readobj -relocs %t2 | FileCheck --check-prefix=IREL1 %s
+// RUN: ld.lld %t.o %t-ro-abs.o -o %t3
+// RUN: llvm-readobj -relocs %t3 | FileCheck --check-prefix=IREL1 %s
+// RUN: ld.lld %t.o %t-rw-addend.o -o %t4
+// RUN: llvm-readobj -relocs %t4 | FileCheck --check-prefix=IREL1 %s
+// RUN: llvm-objdump -s %t4 | FileCheck --check-prefix=DUMP %s
+// RUN: ld.lld %t.o %t-rw-addend.o -o %t4a -z retpolineplt
+// RUN: llvm-readobj -relocs %t4a | FileCheck --check-prefix=IREL1 %s
+// RUN: llvm-objdump -s %t4a | FileCheck --check-prefix=DUMP2 %s
+// RUN: ld.lld %t-ro-pcrel.o %t.o -o %t5
+// RUN: llvm-readobj -relocs %t5 | FileCheck --check-prefix=IREL1 %s
+// RUN: ld.lld %t-ro-abs.o %t.o -o %t6
+// RUN: llvm-readobj -relocs %t6 | FileCheck --check-prefix=IREL1 %s
+// RUN: ld.lld %t-rw-addend.o %t.o -o %t7
+// RUN: llvm-readobj -relocs %t7 | FileCheck --check-prefix=IREL1 %s
+// RUN: ld.lld %t.o -o %t8 -pie
+// RUN: llvm-readobj -relocs %t8 | FileCheck --check-prefix=IREL2 %s
+// RUN: ld.lld %t.o %t-ro-pcrel.o -o %t9 -pie
+// RUN: llvm-readobj -relocs %t9 | FileCheck --check-prefix=IREL1-REL2 %s
+// RUN: ld.lld %t.o %t-rw-addend.o -o %t10 -pie
+// RUN: llvm-readobj -relocs %t10 | FileCheck --check-prefix=IREL1-REL3 %s
+// RUN: ld.lld %t-ro-pcrel.o %t.o -o %t11 -pie
+// RUN: llvm-readobj -relocs %t11 | FileCheck --check-prefix=IREL1-REL2 %s
+// RUN: ld.lld %t-rw-addend.o %t.o -o %t12 -pie
+// RUN: llvm-readobj -relocs %t12 | FileCheck --check-prefix=IREL1-REL3 %s
+
+// Two relocs, one for the GOT and the other for .data.
+// IREL2-NOT: R_X86_64_
+// IREL2: .rela.plt
+// IREL2-NEXT: R_X86_64_IRELATIVE
+// IREL2-NEXT: R_X86_64_IRELATIVE
+// IREL2-NOT: R_X86_64_
+
+// One reloc for the canonical PLT.
+// IREL1-NOT: R_X86_64_
+// IREL1: .rela.plt
+// IREL1-NEXT: R_X86_64_IRELATIVE
+// IREL1-NOT: R_X86_64_
+
+// One reloc for the canonical PLT and two RELATIVE relocations pointing to it,
+// one in the GOT and one in .data.
+// IREL1-REL2-NOT: R_X86_64_
+// IREL1-REL2: .rela.dyn
+// IREL1-REL2-NEXT: R_X86_64_RELATIVE
+// IREL1-REL2-NEXT: R_X86_64_RELATIVE
+// IREL1-REL2: .rela.plt
+// IREL1-REL2-NEXT: R_X86_64_IRELATIVE
+// IREL1-REL2-NOT: R_X86_64_
+
+// One reloc for the canonical PLT and three RELATIVE relocations pointing to it,
+// one in the GOT and two in .data.
+// IREL1-REL3-NOT: R_X86_64_
+// IREL1-REL3: .rela.dyn
+// IREL1-REL3-NEXT: R_X86_64_RELATIVE
+// IREL1-REL3-NEXT: R_X86_64_RELATIVE
+// IREL1-REL3-NEXT: R_X86_64_RELATIVE
+// IREL1-REL3: .rela.plt
+// IREL1-REL3-NEXT: R_X86_64_IRELATIVE
+// IREL1-REL3-NOT: R_X86_64_
+
+// Make sure the static relocations look right, both with and without headers.
+// DUMP: Contents of section .plt:
+// DUMP-NEXT: 201010
+// DUMP: Contents of section .data:
+// DUMP-NEXT: 202000 10102000 00000000 11102000 00000000
+// DUMP: Contents of section .got:
+// DUMP-NEXT: 203000 10102000 00000000
+
+// DUMP2: Contents of section .plt:
+// DUMP2-NEXT: 201010
+// DUMP2: Contents of section .data:
+// DUMP2-NEXT: 202000 40102000 00000000 41102000 00000000
+// DUMP2: Contents of section .got:
+// DUMP2-NEXT: 203000 40102000 00000000
+
+lea ifunc at gotpcrel(%rip), %rbx
+
+.type ifunc STT_GNU_IFUNC
+.globl ifunc
+ifunc:
+ret
+
+.data
+.8byte ifunc
Modified: lld/trunk/test/ELF/gnu-ifunc-i386.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/gnu-ifunc-i386.s?rev=353981&r1=353980&r2=353981&view=diff
==============================================================================
--- lld/trunk/test/ELF/gnu-ifunc-i386.s (original)
+++ lld/trunk/test/ELF/gnu-ifunc-i386.s Wed Feb 13 13:49:55 2019
@@ -70,28 +70,46 @@
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: bar
+// CHECK-NEXT: Value: 0x401030
+// CHECK-NEXT: Size: 0
+// CHECK-NEXT: Binding: Global
+// CHECK-NEXT: Type: Function
+// CHECK-NEXT: Other: 0
+// CHECK-NEXT: Section: .plt
+// CHECK-NEXT: }
+// CHECK-NEXT: Symbol {
+// CHECK-NEXT: Name: bar_resolver
// CHECK-NEXT: Value: 0x401001
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global
-// CHECK-NEXT: Type: GNU_IFunc
+// CHECK-NEXT: Type: Function
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text
// CHECK-NEXT: }
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: foo
+// CHECK-NEXT: Value: 0x401020
+// CHECK-NEXT: Size: 0
+// CHECK-NEXT: Binding: Global
+// CHECK-NEXT: Type: Function
+// CHECK-NEXT: Other: 0
+// CHECK-NEXT: Section: .plt
+// CHECK-NEXT: }
+// CHECK-NEXT: Symbol {
+// CHECK-NEXT: Name: foo_resolver
// CHECK-NEXT: Value: 0x401000
// CHECK-NEXT: Size: 0
// CHECK-NEXT: Binding: Global
-// CHECK-NEXT: Type: GNU_IFunc
+// CHECK-NEXT: Type: Function
// CHECK-NEXT: Other: 0
// CHECK-NEXT: Section: .text
// CHECK-NEXT: }
// CHECK-NEXT:]
// DISASM: Disassembly of section .text:
-// DISASM-NEXT: foo:
+// DISASM-NEXT: foo_resolver:
// DISASM-NEXT: 401000: c3 retl
-// DISASM: bar:
+// DISASM: bar_resolver:
// DISASM-NEXT: 401001: c3 retl
// DISASM: _start:
// DISASM-NEXT: 401002: e8 19 00 00 00 calll 25
@@ -99,10 +117,11 @@
// DISASM-NEXT: 40100c: ba d4 00 40 00 movl $4194516, %edx
// DISASM-NEXT: 401011: ba e4 00 40 00 movl $4194532, %edx
// DISASM-NEXT: Disassembly of section .plt:
-// DISASM-NEXT: .plt:
+// DISASM-NEXT: foo:
// DISASM-NEXT: 401020: ff 25 00 20 40 00 jmpl *4202496
// DISASM-NEXT: 401026: 68 10 00 00 00 pushl $16
// DISASM-NEXT: 40102b: e9 e0 ff ff ff jmp -32 <_start+0xe>
+// DISASM: bar:
// DISASM-NEXT: 401030: ff 25 04 20 40 00 jmpl *4202500
// DISASM-NEXT: 401036: 68 18 00 00 00 pushl $24
// DISASM-NEXT: 40103b: e9 d0 ff ff ff jmp -48 <_start+0xe>
@@ -111,11 +130,17 @@
.type foo STT_GNU_IFUNC
.globl foo
foo:
+.type foo_resolver STT_FUNC
+.globl foo_resolver
+foo_resolver:
ret
.type bar STT_GNU_IFUNC
.globl bar
bar:
+.type bar_resolver STT_FUNC
+.globl bar_resolver
+bar_resolver:
ret
.globl _start
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