[PATCH v2 1/5] BPF: Use a provisional ELF e_machine value

[Richard Henderson via llvm-commits]

This same value for EM_BPF is being propagated to glibc,
elfutils, and binutils.

Signed-off-by: Richard Henderson <rth at twiddle.net>
---
 include/llvm/Object/ELFObjectFile.h                | 5 +++++
 include/llvm/Support/ELF.h                         | 7 +++++++
 include/llvm/Support/ELFRelocs/BPF.def             | 9 +++++++++
 lib/Object/ELF.cpp                                 | 6 ++++++
 lib/ObjectYAML/ELFYAML.cpp                         | 4 ++++
 lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp | 7 ++++++-
 tools/llvm-objdump/llvm-objdump.cpp                | 1 +
 tools/llvm-readobj/ELFDumper.cpp                   | 1 +
 8 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 include/llvm/Support/ELFRelocs/BPF.def

diff --git a/include/llvm/Object/ELFObjectFile.h b/include/llvm/Object/ELFObjectFile.h
index f930088..f006f06 100644
--- a/include/llvm/Object/ELFObjectFile.h
+++ b/include/llvm/Object/ELFObjectFile.h
@@ -886,6 +886,8 @@ StringRef ELFObjectFile<ELFT>::getFileFormatName() const {
       return (EF.getHeader()->e_ident[ELF::EI_OSABI] == ELF::ELFOSABI_AMDGPU_HSA
               && IsLittleEndian) ?
              "ELF64-amdgpu-hsacobj" : "ELF64-amdgpu";
+    case ELF::EM_BPF:
+      return "ELF64-BPF";
     default:
       return "ELF64-unknown";
     }
@@ -948,6 +950,9 @@ unsigned ELFObjectFile<ELFT>::getArch() const {
          && IsLittleEndian) ?
       Triple::amdgcn : Triple::UnknownArch;
 
+  case ELF::EM_BPF:
+    return (IsLittleEndian ? Triple::bpfel : Triple::bpfeb);
+
   default:
     return Triple::UnknownArch;
   }
diff --git a/include/llvm/Support/ELF.h b/include/llvm/Support/ELF.h
index e3c77f4..1df8658 100644
--- a/include/llvm/Support/ELF.h
+++ b/include/llvm/Support/ELF.h
@@ -311,6 +311,8 @@ enum {
   EM_CSR_KALIMBA   = 219, // CSR Kalimba architecture family
   EM_AMDGPU        = 224, // AMD GPU architecture
 
+  EM_BPF           = 247, // Linux kernel bpf virtual machine
+
   // A request has been made to the maintainer of the official registry for
   // such numbers for an official value for WebAssembly. As soon as one is
   // allocated, this enum will be updated to use it.
@@ -620,6 +622,11 @@ enum {
 #include "ELFRelocs/AMDGPU.def"
 };
 
+// ELF Relocation types for BPF
+enum {
+#include "ELFRelocs/BPF.def"
+};
+
 #undef ELF_RELOC
 
 // Section header.
diff --git a/include/llvm/Support/ELFRelocs/BPF.def b/include/llvm/Support/ELFRelocs/BPF.def
new file mode 100644
index 0000000..868974d
--- /dev/null
+++ b/include/llvm/Support/ELFRelocs/BPF.def
@@ -0,0 +1,9 @@
+#ifndef ELF_RELOC
+#error "ELF_RELOC must be defined"
+#endif
+
+// No relocation
+ELF_RELOC(R_BPF_NONE,        0)
+// Map index in "maps" section to file descriptor
+// within ld_64 instruction.
+ELF_RELOC(R_BPF_MAP_FD,      1)
diff --git a/lib/Object/ELF.cpp b/lib/Object/ELF.cpp
index 4002eb7..2dde18a 100644
--- a/lib/Object/ELF.cpp
+++ b/lib/Object/ELF.cpp
@@ -111,6 +111,12 @@ StringRef getELFRelocationTypeName(uint32_t Machine, uint32_t Type) {
     default:
       break;
     }
+  case ELF::EM_BPF:
+    switch (Type) {
+#include "llvm/Support/ELFRelocs/BPF.def"
+    default:
+      break;
+    }
     break;
   default:
     break;
diff --git a/lib/ObjectYAML/ELFYAML.cpp b/lib/ObjectYAML/ELFYAML.cpp
index a480783..527fc9b 100644
--- a/lib/ObjectYAML/ELFYAML.cpp
+++ b/lib/ObjectYAML/ELFYAML.cpp
@@ -195,6 +195,7 @@ ScalarEnumerationTraits<ELFYAML::ELF_EM>::enumeration(IO &IO,
   ECase(EM_56800EX)
   ECase(EM_AMDGPU)
   ECase(EM_LANAI)
+  ECase(EM_BPF)
 #undef ECase
 }
 
@@ -534,6 +535,9 @@ void ScalarEnumerationTraits<ELFYAML::ELF_REL>::enumeration(
   case ELF::EM_AMDGPU:
 #include "llvm/Support/ELFRelocs/AMDGPU.def"
     break;
+  case ELF::EM_BPF:
+#include "llvm/Support/ELFRelocs/BPF.def"
+    break;
   default:
     llvm_unreachable("Unsupported architecture");
   }
diff --git a/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp b/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp
index 115f010..50a88b7 100644
--- a/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp
+++ b/lib/Target/BPF/MCTargetDesc/BPFELFObjectWriter.cpp
@@ -28,7 +28,7 @@ protected:
 }
 
 BPFELFObjectWriter::BPFELFObjectWriter(uint8_t OSABI)
-    : MCELFObjectTargetWriter(/*Is64Bit*/ true, OSABI, ELF::EM_NONE,
+    : MCELFObjectTargetWriter(/*Is64Bit*/ true, OSABI, ELF::EM_BPF,
                               /*HasRelocationAddend*/ false) {}
 
 BPFELFObjectWriter::~BPFELFObjectWriter() {}
@@ -37,6 +37,11 @@ unsigned BPFELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
                                           const MCFixup &Fixup,
                                           bool IsPCRel) const {
   // determine the type of the relocation
+  // ??? Give these some proper names.
+  // ??? Note that R_BPF_MAP_FD (= R_X86_64_64) is the only relocation
+  // supported by the loader.  Which others of these actually need
+  // to be emitted in the circumstances?
+
   switch ((unsigned)Fixup.getKind()) {
   default:
     llvm_unreachable("invalid fixup kind!");
diff --git a/tools/llvm-objdump/llvm-objdump.cpp b/tools/llvm-objdump/llvm-objdump.cpp
index 3beb01a..31e12f1 100644
--- a/tools/llvm-objdump/llvm-objdump.cpp
+++ b/tools/llvm-objdump/llvm-objdump.cpp
@@ -583,6 +583,7 @@ static std::error_code getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
   case ELF::EM_ARM:
   case ELF::EM_HEXAGON:
   case ELF::EM_MIPS:
+  case ELF::EM_BPF:
     res = Target;
     break;
   case ELF::EM_WEBASSEMBLY:
diff --git a/tools/llvm-readobj/ELFDumper.cpp b/tools/llvm-readobj/ELFDumper.cpp
index 84e368e..06fbe8d 100644
--- a/tools/llvm-readobj/ELFDumper.cpp
+++ b/tools/llvm-readobj/ELFDumper.cpp
@@ -956,6 +956,7 @@ static const EnumEntry<unsigned> ElfMachineType[] = {
   ENUM_ENT(EM_AMDGPU,        "EM_AMDGPU"),
   ENUM_ENT(EM_WEBASSEMBLY,   "EM_WEBASSEMBLY"),
   ENUM_ENT(EM_LANAI,         "EM_LANAI"),
+  ENUM_ENT(EM_BPF,           "EM_BPF"),
 };
 
 static const EnumEntry<unsigned> ElfSymbolBindings[] = {
-- 
2.5.5