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Revert "[ELF2] - Implemented rel[a].plt sections" 

This reverts commit r249816.

It broke building llvm with lld:

$ ./bin/FileCheck
./bin/FileCheck: error while loading shared libraries: unexpected PLT reloc type 0x06

I think the only thing that is wrong with this patch is that it is too soon.

The plt we create (and its relocs) don't support lazy loading, so they have
to be relocated as ordinary dynamic relocations.

llvm-svn: 249835
This commit is contained in:
Rafael Espindola 2015-10-09 14:25:49 +00:00
parent 0aace13d18
commit d540919ff1
6 changed files with 29 additions and 55 deletions
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24
lld/ELF/OutputSections.cpp
View File

@ -48,10 +48,6 @@ template <> RelocationSection<ELF32BE> *Out<ELF32BE>::RelaDyn = nullptr;
template <> RelocationSection<ELF32LE> *Out<ELF32LE>::RelaDyn = nullptr;
template <> RelocationSection<ELF64BE> *Out<ELF64BE>::RelaDyn = nullptr;
template <> RelocationSection<ELF64LE> *Out<ELF64LE>::RelaDyn = nullptr;
template <> RelocationSection<ELF32BE> *Out<ELF32BE>::RelaPlt = nullptr;
template <> RelocationSection<ELF32LE> *Out<ELF32LE>::RelaPlt = nullptr;
template <> RelocationSection<ELF64BE> *Out<ELF64BE>::RelaPlt = nullptr;
template <> RelocationSection<ELF64LE> *Out<ELF64LE>::RelaPlt = nullptr;
template <> StringTableSection<false> *Out<ELF32BE>::DynStrTab = nullptr;
template <> StringTableSection<false> *Out<ELF32LE>::DynStrTab = nullptr;
template <> StringTableSection<true> *Out<ELF64BE>::DynStrTab = nullptr;
@ -143,9 +139,10 @@ void PltSection<ELFT>::finalize() {
}
template <class ELFT>
RelocationSection<ELFT>::RelocationSection(StringRef Name, bool IsRela)
: OutputSectionBase<ELFT::Is64Bits>(Name, IsRela ? llvm::ELF::SHT_RELA
: llvm::ELF::SHT_REL,
RelocationSection<ELFT>::RelocationSection(bool IsRela)
: OutputSectionBase<ELFT::Is64Bits>(IsRela ? ".rela.dyn" : ".rel.dyn",
IsRela ? llvm::ELF::SHT_RELA
: llvm::ELF::SHT_REL,
llvm::ELF::SHF_ALLOC),
IsRela(IsRela) {
this->Header.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
@ -303,13 +300,6 @@ template <class ELFT> void DynamicSection<ELFT>::finalize() {
++NumEntries; // DT_RELASZ / DT_RELSZ
++NumEntries; // DT_RELAENT / DT_RELENT
}
if (Out<ELFT>::RelaPlt->hasRelocs()) {
++NumEntries; // DT_JMPREL
++NumEntries; // DT_PLTRELSZ
++NumEntries; // DT_PLTGOT
++NumEntries; // DT_PLTREL
}
++NumEntries; // DT_SYMTAB
++NumEntries; // DT_SYMENT
++NumEntries; // DT_STRTAB
@ -377,12 +367,6 @@ template <class ELFT> void DynamicSection<ELFT>::writeTo(uint8_t *Buf) {
WriteVal(IsRela ? DT_RELAENT : DT_RELENT,
IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel));
}
if (Out<ELFT>::RelaPlt->hasRelocs()) {
WritePtr(DT_JMPREL, Out<ELFT>::RelaPlt->getVA());
WriteVal(DT_PLTRELSZ, Out<ELFT>::RelaPlt->getSize());
WritePtr(DT_PLTGOT, Out<ELFT>::Got->getVA());
WriteVal(DT_PLTREL, Out<ELFT>::RelaPlt->isRela() ? DT_RELA : DT_REL);
}
WritePtr(DT_SYMTAB, Out<ELFT>::DynSymTab->getVA());
WritePtr(DT_SYMENT, sizeof(Elf_Sym));

3
lld/ELF/OutputSections.h
View File

@ -171,7 +171,7 @@ class RelocationSection final : public OutputSectionBase<ELFT::Is64Bits> {
typedef typename llvm::object::ELFFile<ELFT>::uintX_t uintX_t;
public:
RelocationSection(StringRef Name, bool IsRela);
RelocationSection(bool IsRela);
void addReloc(const DynamicReloc<ELFT> &Reloc) { Relocs.push_back(Reloc); }
void finalize() override;
void writeTo(uint8_t *Buf) override;
@ -289,7 +289,6 @@ template <class ELFT> struct Out {
static OutputSection<ELFT> *Bss;
static PltSection<ELFT> *Plt;
static RelocationSection<ELFT> *RelaDyn;
static RelocationSection<ELFT> *RelaPlt;
static StringTableSection<ELFT::Is64Bits> *DynStrTab;
static StringTableSection<ELFT::Is64Bits> *StrTab;
static SymbolTableSection<ELFT> *DynSymTab;

19
lld/ELF/Writer.cpp
View File

@ -134,11 +134,8 @@ template <class ELFT> static void doWriteResult(SymbolTable *Symtab) {
Out<ELFT>::DynSymTab = &DynSymTab;
HashTableSection<ELFT> HashTab;
Out<ELFT>::HashTab = &HashTab;
bool IsRela = Symtab->shouldUseRela();
RelocationSection<ELFT> RelaDyn(IsRela ? ".rela.dyn" : ".rel.dyn", IsRela);
RelocationSection<ELFT> RelaDyn(Symtab->shouldUseRela());
Out<ELFT>::RelaDyn = &RelaDyn;
RelocationSection<ELFT> RelaPlt(IsRela ? ".rela.plt" : ".rel.plt", IsRela);
Out<ELFT>::RelaPlt = &RelaPlt;
DynamicSection<ELFT> Dynamic(*Symtab);
Out<ELFT>::Dynamic = &Dynamic;
@ -236,15 +233,11 @@ void Writer<ELFT>::scanRelocs(
Out<ELFT>::Got->addEntry(Body);
}
}
bool CanBePreempted = canBePreempted(Body);
if (CanBePreempted)
if (canBePreempted(Body)) {
Body->setUsedInDynamicReloc();
if (CanBePreempted || (Config->Shared && !Target->isRelRelative(Type))) {
if (Body && Body->isInPlt())
Out<ELFT>::RelaPlt->addReloc({C, RI});
else
Out<ELFT>::RelaDyn->addReloc({C, RI});
Out<ELFT>::RelaDyn->addReloc({C, RI});
} else if (Config->Shared && !Target->isRelRelative(Type)) {
Out<ELFT>::RelaDyn->addReloc({C, RI});
}
}
}
@ -473,8 +466,6 @@ template <class ELFT> void Writer<ELFT>::createSections() {
OutputSections.push_back(Out<ELFT>::DynStrTab);
if (Out<ELFT>::RelaDyn->hasRelocs())
OutputSections.push_back(Out<ELFT>::RelaDyn);
if (Out<ELFT>::RelaPlt->hasRelocs())
OutputSections.push_back(Out<ELFT>::RelaPlt);
}
if (!Out<ELFT>::Got->empty())
OutputSections.push_back(Out<ELFT>::Got);

14
lld/test/elf2/plt-i686.s
View File

@ -20,9 +20,9 @@
// CHECK-NEXT: AddressAlignment: 16
// CHECK: Relocations [
// CHECK-NEXT: Section ({{.*}}) .rel.plt {
// CHECK-NEXT: 0x13058 R_386_GLOB_DAT bar 0x0
// CHECK-NEXT: 0x1305C R_386_GLOB_DAT zed 0x0
// CHECK-NEXT: Section ({{.*}}) .rel.dyn {
// CHECK-NEXT: 0x13050 R_386_GLOB_DAT bar 0x0
// CHECK-NEXT: 0x13054 R_386_GLOB_DAT zed 0x0
// CHECK-NEXT: }
// CHECK-NEXT: ]
@ -38,15 +38,15 @@
// DISASM-NEXT: 12005: e9 06 00 00 00 jmp 6
// DISASM-NEXT: 1200a: e9 09 00 00 00 jmp 9
// 0x13058 = 77912
// 0x1305C = 77916
// 0x13050 = 77904
// 0x13054 = 77908
// DISASM: Disassembly of section .plt:
// DISASM-NEXT: .plt:
// DISASM-NEXT: 12010: ff 25 {{.*}} jmpl *77912
// DISASM-NEXT: 12010: ff 25 {{.*}} jmpl *77904
// DISASM-NEXT: 12016: 90 nop
// DISASM-NEXT: 12017: 90 nop
// DISASM-NEXT: 12018: ff 25 {{.*}} jmpl *77916
// DISASM-NEXT: 12018: ff 25 {{.*}} jmpl *77908
// DISASM-NEXT: 1201e: 90 nop
// DISASM-NEXT: 1201f: 90 nop

16
lld/test/elf2/plt.s
View File

@ -20,10 +20,10 @@
// CHECK-NEXT: AddressAlignment: 16
// CHECK: Relocations [
// CHECK-NEXT: Section ({{.*}}) .rela.plt {
// CHECK-NEXT: 0x30B0 R_X86_64_GLOB_DAT bar 0x0
// CHECK-NEXT: 0x30B8 R_X86_64_GLOB_DAT zed 0x0
// CHECK-NEXT: 0x30C0 R_X86_64_GLOB_DAT _start 0x0
// CHECK-NEXT: Section ({{.*}}) .rela.dyn {
// CHECK-NEXT: 0x30A0 R_X86_64_GLOB_DAT bar 0x0
// CHECK-NEXT: 0x30A8 R_X86_64_GLOB_DAT zed 0x0
// CHECK-NEXT: 0x30B0 R_X86_64_GLOB_DAT _start 0x0
// CHECK-NEXT: }
// CHECK-NEXT: ]
@ -39,15 +39,15 @@
// DISASM-NEXT: 2005: e9 {{.*}} jmp 22
// DISASM-NEXT: 200a: e9 {{.*}} jmp 25
// 0x30B0 - 0x2026 = 4234
// 0x30B8 - 0x202e = 4234
// 0x130A0 - 0x12026 = 4218
// 0x130A8 - 0x1202e = 4218
// DISASM: Disassembly of section .plt:
// DISASM-NEXT: .plt:
// DISASM-NEXT: 2020: ff 25 {{.*}} jmpq *4234(%rip)
// DISASM-NEXT: 2020: ff 25 {{.*}} jmpq *4218(%rip)
// DISASM-NEXT: 2026: 90 nop
// DISASM-NEXT: 2027: 90 nop
// DISASM-NEXT: 2028: ff 25 {{.*}} jmpq *4234(%rip)
// DISASM-NEXT: 2028: ff 25 {{.*}} jmpq *4218(%rip)
// DISASM-NEXT: 202e: 90 nop
// DISASM-NEXT: 202f: 90 nop

8
lld/test/elf2/relocation.s
View File

@ -22,7 +22,7 @@
// SEC-NEXT: SHF_ALLOC
// SEC-NEXT: SHF_WRITE
// SEC-NEXT: ]
// SEC-NEXT: Address: 0x130E0
// SEC-NEXT: Address: 0x130A0
// SEC-NEXT: Offset:
// SEC-NEXT: Size: 16
// SEC-NEXT: Link: 0
@ -93,7 +93,7 @@ R_X86_64_64:
R_X86_64_GOTPCREL:
.long zed@gotpcrel
// 0x130E8 - 0x11008 = 8416
// 8416 = 0xE0200000 in little endian
// 0x130A8 - 0x11008 = 8352
// 8352 = 0x80200000 in little endian
// CHECK: Contents of section .R_X86_64_GOTPCREL
// CHECK-NEXT: 11008 e0200000
// CHECK-NEXT: 11008 a0200000