[lld] [ELF/AArch64] Fix local TLS relocations

[zatrazz]

Summary

This patch fixes the R_AARCH64_TLSLE_ADD_TPREL_HI12 and R_AARCH64_TLSLE_ADD_TPREL_LO12_NC
handling by using the correct offset by using the target layout along with
aarch64 alignments requirements.

It fixes the TLS test-suite SingleSource failures for aarch64:

• SingleSource/UnitTests/Threads/2010-12-08-tls.execution_time
• SingleSource/UnitTests/Threads/tls.execution_time

[shankarke]

lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp

476–479

can you move the case statement to a new line ?

477

Do relocations increase the size of the initial TLS image ? Confused.

[ruiu]

LGTM

lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.h

31

Let's use C++11 non-member initialization:

mutable uint64_t _tlsSize = 0;

lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.h

 #ifndef AARCH64_RELOCATION_HANDLER_H
 #define AARCH64_RELOCATION_HANDLER_H
 
 #include "lld/ReaderWriter/ELFLinkingContext.h"
 
 namespace lld {
 namespace elf {
 
+class AArch64TargetLayout;
+
 class AArch64TargetRelocationHandler final : public TargetRelocationHandler {
 public:
+  AArch64TargetRelocationHandler(AArch64TargetLayout &layout)
+      : _tlsSize(0), _layout(layout) {}
+
   std::error_code applyRelocation(ELFWriter &, llvm::FileOutputBuffer &,
                                   const AtomLayout &,
                                   const Reference &) const override;
+
+private:
+  // Cached size of the TLS segment.
+  mutable uint64_t _tlsSize;
+  AArch64TargetLayout &_layout;
 };
 
 } // end namespace elf
 } // end namespace lld
 
 #endif // AArch64_RELOCATION_HANDLER_H

lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp

std::error_code AArch64TargetRelocationHandler::applyRelocation(
   case ADD_AARCH64_GOTRELINDEX:
     relocADD_AARCH64_GOTRELINDEX(loc, reloc, target, addend);
     break;
   case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
     return relocR_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21(loc, reloc, target, addend);
   case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
     relocR_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC(loc, reloc, target, addend);
     break;
-  case R_AARCH64_TLSLE_ADD_TPREL_HI12:
-    return relocR_AARCH64_TLSLE_ADD_TPREL_HI12(loc, reloc, target, addend);
-  case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
-    relocR_AARCH64_TLSLE_ADD_TPREL_LO12_NC(loc, reloc, target, addend);
-    break;
+  case R_AARCH64_TLSLE_ADD_TPREL_HI12: {
+    _tlsSize = _layout.getAlignedTLSSize();
+    return relocR_AARCH64_TLSLE_ADD_TPREL_HI12(loc, reloc, target + _tlsSize, addend);
+  } case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC: {
+    _tlsSize = _layout.getAlignedTLSSize();
+    relocR_AARCH64_TLSLE_ADD_TPREL_LO12_NC(loc, reloc, target + _tlsSize, addend);
+  }  break;
   default:
     return make_unhandled_reloc_error();
   }
   return std::error_code();
 }

lib/ReaderWriter/ELF/AArch64/AArch64TargetHandler.h

 #include "ELFReader.h"
 #include "TargetLayout.h"
 #include "lld/Core/Simple.h"
 
 namespace lld {
 namespace elf {
 class AArch64LinkingContext;
 
+class AArch64TargetLayout final : public TargetLayout<ELF64LE> {
+public:
+  AArch64TargetLayout(ELFLinkingContext &ctx) : TargetLayout(ctx) {}
+
+  uint64_t getAlignedTLSSize() const {
+    return llvm::RoundUpToAlignment(TCB_ALIGNMENT, this->getTLSSize());
+  }
+
+private:
+  // Alignment requirement for TCB.
+  enum { TCB_ALIGNMENT = 0x10 };
+};
+
 class AArch64TargetHandler final : public TargetHandler {
 public:
   AArch64TargetHandler(AArch64LinkingContext &ctx);
 
   const TargetRelocationHandler &getRelocationHandler() const override {
     return *_relocationHandler;
   }
 
   std::unique_ptr<Reader> getObjReader() override {
     return llvm::make_unique<ELFReader<ELFFile<ELF64LE>>>(_ctx);
   }
 
   std::unique_ptr<Reader> getDSOReader() override {
     return llvm::make_unique<ELFReader<DynamicFile<ELF64LE>>>(_ctx);
   }
 
   std::unique_ptr<Writer> getWriter() override;
 
 private:
   AArch64LinkingContext &_ctx;
-  std::unique_ptr<TargetLayout<ELF64LE>> _targetLayout;
+  std::unique_ptr<AArch64TargetLayout> _targetLayout;
   std::unique_ptr<AArch64TargetRelocationHandler> _relocationHandler;
 };
 
 } // end namespace elf
 } // end namespace lld
 
 #endif

lib/ReaderWriter/ELF/AArch64/AArch64TargetHandler.cpp

 #include "AArch64ExecutableWriter.h"
 #include "AArch64LinkingContext.h"
 #include "AArch64TargetHandler.h"
 
 using namespace lld;
 using namespace elf;
 
 AArch64TargetHandler::AArch64TargetHandler(AArch64LinkingContext &ctx)
-    : _ctx(ctx), _targetLayout(new TargetLayout<ELF64LE>(ctx)),
-      _relocationHandler(new AArch64TargetRelocationHandler()) {}
+    : _ctx(ctx), _targetLayout(new AArch64TargetLayout(ctx)),
+      _relocationHandler(new AArch64TargetRelocationHandler(*_targetLayout)) {}
 
 std::unique_ptr<Writer> AArch64TargetHandler::getWriter() {
   switch (this->_ctx.getOutputELFType()) {
   case llvm::ELF::ET_EXEC:
     return llvm::make_unique<AArch64ExecutableWriter>(_ctx, *_targetLayout);
   case llvm::ELF::ET_DYN:
     return llvm::make_unique<AArch64DynamicLibraryWriter>(_ctx, *_targetLayout);
   case llvm::ELF::ET_REL:
     llvm_unreachable("TODO: support -r mode");
   default:
     llvm_unreachable("unsupported output type");
   }
 }

test/elf/AArch64/local-tls.test

+# Check for correct offsets when handling relocations for local TLS
+# access (R_AARCH64_TLSLE_ADD_TPREL_HI12, R_AARCH64_TLSLE_ADD_TPREL_LO12_NC)
+# RUN: yaml2obj -format=elf %s > %t-obj
+# RUN: lld -flavor gnu -target arm64 --noinhibit-exec -o %t-exe %t-obj
+# RUN: llvm-objdump -s -t %t-exe | FileCheck %s
+
+# CHECK: Contents of section .text:
+# CHECK-NEXT: 4001dc 48d03bd5 08010091 08410091 090140b9  H.;......A....@.
+#                              \_      |        add  x8, x8, #0x0   (R_AARCH64_TLSLE_ADD_TPREL_HI12)
+#                                      \_       add  x8, x8, #0x10  (R_AARCH64_TLSLE_ADD_TPREL_LO12_NC)
+
+---
+FileHeader:      
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  OSABI:           ELFOSABI_GNU
+  Type:            ET_REL
+  Machine:         EM_AARCH64
+Sections:        
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:    0x0000000000000004
+    Content:         48D03BD50801009108010091090140B9E003092AC0035FD6FD7BBFA9FD030091FF4300D1BFC31FB8F6FFFF97BF030091FD7BC1A8C0035FD6
+  - Name:            .rela.text
+    Type:            SHT_RELA
+    Link:            .symtab
+    AddressAlign:    0x0000000000000008
+    Info:            .text
+    Relocations:     
+      - Offset:          0x0000000000000004
+        Symbol:          a
+        Type:            R_AARCH64_TLSLE_ADD_TPREL_HI12
+      - Offset:          0x0000000000000008
+        Symbol:          a
+        Type:            R_AARCH64_TLSLE_ADD_TPREL_LO12_NC
+  - Name:            .data
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000004
+    Content:         ''
+  - Name:            .bss
+    Type:            SHT_NOBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    AddressAlign:    0x0000000000000004
+    Content:         ''
+  - Name:            .tdata
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_WRITE, SHF_ALLOC, SHF_TLS ]
+    AddressAlign:    0x0000000000000004
+    Content:         '04000000'
+  - Name:            .comment
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_MERGE, SHF_STRINGS ]
+    AddressAlign:    0x0000000000000001
+    Content:         00636C616E672076657273696F6E20332E372E302028687474703A2F2F6C6C766D2E6F72672F6769742F636C616E672E6769742039636664333732343263346635623866393362636462343536366163636565373962306563653666292028687474703A2F2F6C6C766D2E6F72672F6769742F6C6C766D2E67697420653262383764656531656531393835396561383334313565616365333533666130323362646462302900
+  - Name:            .note.GNU-stack
+    Type:            SHT_PROGBITS
+    AddressAlign:    0x0000000000000001
+    Content:         ''
+Symbols:         
+  Local:           
+    - Name:            '$d.1'
+      Type:            STT_TLS
+      Section:         .tdata
+    - Name:            '$d.2'
+      Section:         .comment
+    - Name:            '$x.0'
+      Section:         .text
+    - Name:            .text
+      Type:            STT_SECTION
+      Section:         .text
+    - Name:            .data
+      Type:            STT_SECTION
+      Section:         .data
+    - Name:            .bss
+      Type:            STT_SECTION
+      Section:         .bss
+    - Name:            .tdata
+      Type:            STT_SECTION
+      Section:         .tdata
+    - Name:            .comment
+      Type:            STT_SECTION
+      Section:         .comment
+    - Name:            .note.GNU-stack
+      Type:            STT_SECTION
+      Section:         .note.GNU-stack
+  Global:          
+    - Name:            a
+      Type:            STT_TLS
+      Section:         .tdata
+      Size:            0x0000000000000004
+    - Name:            foo
+      Type:            STT_FUNC
+      Section:         .text
+      Size:            0x0000000000000018
+    - Name:            main
+      Type:            STT_FUNC
+      Section:         .text
+      Value:           0x0000000000000018
+      Size:            0x0000000000000020
+...