[ELF2] Initial (very basic) support for AArch64

[davide]

Summary

We can link now!

root@cavium:/zoo/davide # file ./helloarch
./helloarch: ELF 64-bit LSB executable, ARM aarch64, version 1 (FreeBSD), statically linked, not stripped
root@cavium:/zoo/davide # ./helloarch
root@cavium:/zoo/davide # echo $?
42

[ruiu]

Cool! LGTM but wait for Rafael.

[emaste]

Excellent! Aside, the reference FreeBSD/arm64 platform where @davide ran the result is Cavium's ThunderX.

ELF/SymbolTable.cpp

48–49 ↗

(On Diff #35737)

My usual comment, we ought to keep lists like this sorted in alphanumeric order. Perhaps just put EM_AARCH64 first in this commit and re-sort the rest later?

[• rafael]

LGTM. Please sort the list in a followup commit.

lld/trunk/ELF/SymbolTable.cpp

 }
 
 static TargetInfo *createTarget(uint16_t EMachine) {
   switch (EMachine) {
   case EM_PPC:
     return new PPCTargetInfo();
   case EM_ARM:
     return new ARMTargetInfo();
+  case EM_AARCH64:
+    return new AArch64TargetInfo();
   case EM_PPC64:
     return new PPC64TargetInfo();
   case EM_X86_64:
     return new X86_64TargetInfo();
   case EM_386:
     return new X86TargetInfo();
   }
   error("Unknown target machine");

lld/trunk/ELF/Target.h

public:
   void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                      uint64_t PltEntryAddr) const override;
   bool relocNeedsGot(uint32_t Type) const override;
   bool relocNeedsPlt(uint32_t Type) const override;
   void relocateOne(uint8_t *Buf, const void *RelP, uint32_t Type,
                    uint64_t BaseAddr, uint64_t SymVA) const override;
 };
 
+class AArch64TargetInfo final : public TargetInfo {
+public:
+  AArch64TargetInfo();
+  void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
+                     uint64_t PltEntryAddr) const override;
+  bool relocNeedsGot(uint32_t Type) const override;
+  bool relocNeedsPlt(uint32_t Type) const override;
+  void relocateOne(uint8_t *Buf, const void *RelP, uint32_t Type,
+                   uint64_t BaseAddr, uint64_t SymVA) const override;
+};
+
 extern std::unique_ptr<TargetInfo> Target;
 }
 }
 
 #endif

lld/trunk/ELF/Target.cpp

ARMTargetInfo::ARMTargetInfo() {
   // GotReloc = FIXME
 }
 void ARMTargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                                   uint64_t PltEntryAddr) const {}
 bool ARMTargetInfo::relocNeedsGot(uint32_t Type) const { return false; }
 bool ARMTargetInfo::relocNeedsPlt(uint32_t Type) const { return false; }
 void ARMTargetInfo::relocateOne(uint8_t *Buf, const void *RelP, uint32_t Type,
                                 uint64_t BaseAddr, uint64_t SymVA) const {}
+
+AArch64TargetInfo::AArch64TargetInfo() {
+  // PCRelReloc = FIXME
+  // GotReloc = FIXME
+}
+void AArch64TargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
+                                      uint64_t PltEntryAddr) const {}
+bool AArch64TargetInfo::relocNeedsGot(uint32_t Type) const { return false; }
+bool AArch64TargetInfo::relocNeedsPlt(uint32_t Type) const { return false; }
+void AArch64TargetInfo::relocateOne(uint8_t *Buf, const void *RelP,
+                                    uint32_t Type, uint64_t BaseAddr,
+                                    uint64_t SymVA) const {}
 }
 }

lld/trunk/test/elf2/basic-aarch64.s

+# RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-freebsd %s -o %t
+# RUN: lld -flavor gnu2 %t -o %t2
+# RUN: llvmreadobj -file-headers -sections -program-headers -symbols %t2 \
+# RUN:   | FileCheck %s
+# REQUIRES: x86
+
+# exits with return code 42 on FreeBSD/AArch64
+.globl _start;
+_start:
+  mov    x0, 42
+  mov    x8, 1
+  svc    0
+
+# CHECK:      ElfHeader {
+# CHECK-NEXT:   Ident {
+# CHECK-NEXT:     Magic: (7F 45 4C 46)
+# CHECK-NEXT:     Class: 64-bit (0x2)
+# CHECK-NEXT:     DataEncoding: LittleEndian (0x1)
+# CHECK-NEXT:     FileVersion: 1
+# CHECK-NEXT:     OS/ABI: FreeBSD (0x9)
+# CHECK-NEXT:     ABIVersion: 0
+# CHECK-NEXT:     Unused: (00 00 00 00 00 00 00)
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Type: Executable (0x2)
+# CHECK-NEXT:   Machine: EM_AARCH64 (0xB7)
+# CHECK-NEXT:   Version: 1
+# CHECK-NEXT:   Entry: [[ENTRY:0x[0-9A-F]+]]
+# CHECK-NEXT:   ProgramHeaderOffset: 0x40
+# CHECK-NEXT:   SectionHeaderOffset: 0x1088
+# CHECK-NEXT:   Flags [ (0x0)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   HeaderSize: 64
+# CHECK-NEXT:   ProgramHeaderEntrySize: 56
+# CHECK-NEXT:   ProgramHeaderCount: 2
+# CHECK-NEXT:   SectionHeaderEntrySize: 64
+# CHECK-NEXT:   SectionHeaderCount: 6
+# CHECK-NEXT:   StringTableSectionIndex: 5
+# CHECK-NEXT: }
+# CHECK-NEXT: Sections [
+# CHECK-NEXT:   Section {
+# CHECK-NEXT:     Index: 0
+# CHECK-NEXT:     Name:  (0)
+# CHECK-NEXT:     Type: SHT_NULL (0x0)
+# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Address: 0x0
+# CHECK-NEXT:     Offset: 0x0
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Link: 0
+# CHECK-NEXT:     Info: 0
+# CHECK-NEXT:     AddressAlignment: 0
+# CHECK-NEXT:     EntrySize: 0
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Section {
+# CHECK-NEXT:     Index: 1
+# CHECK-NEXT:     Name: .bss
+# CHECK-NEXT:     Type: SHT_NOBITS (0x8)
+# CHECK-NEXT:     Flags [ (0x3)
+# CHECK-NEXT:       SHF_ALLOC (0x2)
+# CHECK-NEXT:       SHF_WRITE (0x1)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Address: 0x11000
+# CHECK-NEXT:     Offset: 0x1000
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Link: 0
+# CHECK-NEXT:     Info: 0
+# CHECK-NEXT:     AddressAlignment: 4
+# CHECK-NEXT:     EntrySize: 0
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Section {
+# CHECK-NEXT:     Index: 2
+# CHECK-NEXT:     Name: .text
+# CHECK-NEXT:     Type: SHT_PROGBITS (0x1)
+# CHECK-NEXT:     Flags [ (0x6)
+# CHECK-NEXT:       SHF_ALLOC (0x2)
+# CHECK-NEXT:       SHF_EXECINSTR (0x4)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Address: 0x11000
+# CHECK-NEXT:     Offset: 0x1000
+# CHECK-NEXT:     Size: 12
+# CHECK-NEXT:     Link: 0
+# CHECK-NEXT:     Info: 0
+# CHECK-NEXT:     AddressAlignment: 4
+# CHECK-NEXT:     EntrySize: 0
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Section {
+# CHECK-NEXT:     Index: 3
+# CHECK-NEXT:     Name: .data
+# CHECK-NEXT:     Type: SHT_PROGBITS (0x1)
+# CHECK-NEXT:     Flags [ (0x3)
+# CHECK-NEXT:       SHF_ALLOC (0x2)
+# CHECK-NEXT:       SHF_WRITE (0x1)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Address: 0x1100C
+# CHECK-NEXT:     Offset: 0x100C
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Link: 0
+# CHECK-NEXT:     Info: 0
+# CHECK-NEXT:     AddressAlignment: 4
+# CHECK-NEXT:     EntrySize: 0
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Section {
+# CHECK-NEXT:     Index: 4
+# CHECK-NEXT:     Name: .symtab
+# CHECK-NEXT:     Type: SHT_SYMTAB (0x2)
+# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Address: 0x0
+# CHECK-NEXT:     Offset: 0x1010
+# CHECK-NEXT:     Size: 72
+# CHECK-NEXT:     Link: 5
+# CHECK-NEXT:     Info: 2
+# CHECK-NEXT:     AddressAlignment: 8
+# CHECK-NEXT:     EntrySize: 24
+# CHECK-NEXT:  }
+# CHECK-NEXT:  Section {
+# CHECK-NEXT:    Index: 5
+# CHECK-NEXT:     Name: .strtab
+# CHECK-NEXT:     Type: SHT_STRTAB (0x3)
+# CHECK-NEXT:     Flags [ (0x0)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Address: 0x0
+# CHECK-NEXT:     Offset: 0x1058
+# CHECK-NEXT:     Size: 46
+# CHECK-NEXT:     Link: 0
+# CHECK-NEXT:     Info: 0
+# CHECK-NEXT:     AddressAlignment: 1
+# CHECK-NEXT:     EntrySize: 0
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+# CHECK-NEXT: Symbols [
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name:  (0)
+# CHECK-NEXT:     Value: 0x0
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Binding: Local (0x0)
+# CHECK-NEXT:     Type: None (0x0)
+# CHECK-NEXT:     Other: 0
+# CHECK-NEXT:     Section: Undefined (0x0)
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: $x.0 (41)
+# CHECK-NEXT:     Value: 0x11000
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Binding: Local (0x0)
+# CHECK-NEXT:     Type: None (0x0)
+# CHECK-NEXT:     Other: 0
+# CHECK-NEXT:     Section: .text (0x2)
+# CHECK-NEXT:   }
+# CHECK-NEXT:   Symbol {
+# CHECK-NEXT:     Name: _start (7)
+# CHECK-NEXT:     Value: [[ENTRY]]
+# CHECK-NEXT:     Size: 0
+# CHECK-NEXT:     Binding: Global (0x1)
+# CHECK-NEXT:     Type: None (0x0)
+# CHECK-NEXT:     Other: 0
+# CHECK-NEXT:     Section: .text
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+# CHECK-NEXT: ProgramHeaders [
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_LOAD (0x1)
+# CHECK-NEXT:     Offset: 0x0
+# CHECK-NEXT:     VirtualAddress: 0x10000
+# CHECK-NEXT:     PhysicalAddress: 0x10000
+# CHECK-NEXT:     FileSize: 176
+# CHECK-NEXT:     MemSize: 176
+# CHECK-NEXT:     Flags [
+# CHECK-NEXT:       PF_R
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment: 4096
+# CHECK-NEXT:   }
+# CHECK-NEXT:   ProgramHeader {
+# CHECK-NEXT:     Type: PT_LOAD (0x1)
+# CHECK-NEXT:     Offset: 0x1000
+# CHECK-NEXT:     VirtualAddress: 0x11000
+# CHECK-NEXT:     PhysicalAddress: 0x11000
+# CHECK-NEXT:     FileSize: 12 
+# CHECK-NEXT:     MemSize: 12
+# CHECK-NEXT:     Flags [ (0x5)
+# CHECK-NEXT:       PF_R (0x4)
+# CHECK-NEXT:       PF_X (0x1)
+# CHECK-NEXT:     ]
+# CHECK-NEXT:     Alignment: 4096
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]