[ELF] Support for PT_GNU_PROPERTY in header and tools

The PT_GNU_PROPERTY is generated by a linker to describe the
.note.gnu.property section. The Linux kernel uses this program header to
locate the .note.gnu.property section.

It is described in "The Linux gABI extension"

Include support for llvm-readelf, llvm-readobj and the yaml reader and
writers.

Differential Revision: https://reviews.llvm.org/D70959

include/llvm/BinaryFormat/ELF.h

@@ -1199,8 +1199,9 @@ enum {
   PT_SUNW_EH_FRAME = 0x6474e550,
   PT_SUNW_UNWIND = 0x6464e550,
 
-  PT_GNU_STACK = 0x6474e551, // Indicates stack executability.
-  PT_GNU_RELRO = 0x6474e552, // Read-only after relocation.
+  PT_GNU_STACK = 0x6474e551,    // Indicates stack executability.
+  PT_GNU_RELRO = 0x6474e552,    // Read-only after relocation.
+  PT_GNU_PROPERTY = 0x6474e553, // .note.gnu.property notes sections.
 
   PT_OPENBSD_RANDOMIZE = 0x65a3dbe6, // Fill with random data.
   PT_OPENBSD_WXNEEDED = 0x65a3dbe7,  // Program does W^X violations.

lib/ObjectYAML/ELFYAML.cpp

@@ -54,6 +54,7 @@ void ScalarEnumerationTraits<ELFYAML::ELF_PT>::enumeration(
   ECase(PT_GNU_EH_FRAME);
   ECase(PT_GNU_STACK);
   ECase(PT_GNU_RELRO);
+  ECase(PT_GNU_PROPERTY);
 #undef ECase
   IO.enumFallback<Hex32>(Value);
 }

test/tools/llvm-objdump/elf-pt-gnu-property.test

@@ -0,0 +1,14 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objdump -p %t | FileCheck %s
+
+# CHECK: Program Header:
+# CHECK-NEXT: {{ }}PROPERTY{{ }}
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_AARCH64
+ProgramHeaders:
+  - Type: PT_GNU_PROPERTY

test/tools/llvm-readobj/elf-pt-gnu-property.test

@@ -0,0 +1,17 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-readelf --program-headers %t | FileCheck %s --check-prefix=GNU
+# RUN: llvm-readobj --program-headers %t | FileCheck %s --check-prefix=LLVM
+
+# GNU: {{ }}GNU_PROPERTY{{ }}
+
+# LLVM:        ProgramHeader {
+# LLVM-NEXT:     Type: PT_GNU_PROPERTY (0x6474E553)
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_AARCH64
+ProgramHeaders:
+  - Type: PT_GNU_PROPERTY

test/tools/yaml2obj/ELF/program-header.yaml

@@ -40,6 +40,7 @@ ProgramHeaders:
   - Type: PT_GNU_EH_FRAME
   - Type: PT_GNU_STACK
   - Type: PT_GNU_RELRO
+  - Type: PT_GNU_PROPERTY
 
 #CHECK:     ProgramHeaders [
 #CHECK-NEXT:   ProgramHeader {
@@ -76,6 +77,9 @@ ProgramHeaders:
 #CHECK-NEXT:  ProgramHeader {
 #CHECK-NEXT:    Type: PT_GNU_RELRO (0x6474E552)
 #CHECK:       }
+#CHECK-NEXT:  ProgramHeader {
+#CHECK-NEXT:    Type: PT_GNU_PROPERTY (0x6474E553)
+#CHECK:       }
 #CHECK-NEXT:]
 
 ## Check we do not allow referencing sections that do not exist.

tools/llvm-objdump/ELFDump.cpp

@@ -204,6 +204,9 @@ template <class ELFT> void printProgramHeaders(const ELFFile<ELFT> *o) {
     case ELF::PT_GNU_RELRO:
       outs() << "   RELRO ";
       break;
+    case ELF::PT_GNU_PROPERTY:
+      outs() << "   PROPERTY ";
+      break;
     case ELF::PT_GNU_STACK:
       outs() << "   STACK ";
       break;

tools/llvm-readobj/ELFDumper.cpp

@@ -1446,6 +1446,7 @@ static const char *getElfSegmentType(unsigned Arch, unsigned Type) {
 
     LLVM_READOBJ_ENUM_CASE(ELF, PT_GNU_STACK);
     LLVM_READOBJ_ENUM_CASE(ELF, PT_GNU_RELRO);
+    LLVM_READOBJ_ENUM_CASE(ELF, PT_GNU_PROPERTY);
 
     LLVM_READOBJ_ENUM_CASE(ELF, PT_OPENBSD_RANDOMIZE);
     LLVM_READOBJ_ENUM_CASE(ELF, PT_OPENBSD_WXNEEDED);
@@ -1470,6 +1471,7 @@ static std::string getElfPtType(unsigned Arch, unsigned Type) {
     LLVM_READOBJ_PHDR_ENUM(ELF, PT_SUNW_UNWIND)
     LLVM_READOBJ_PHDR_ENUM(ELF, PT_GNU_STACK)
     LLVM_READOBJ_PHDR_ENUM(ELF, PT_GNU_RELRO)
+    LLVM_READOBJ_PHDR_ENUM(ELF, PT_GNU_PROPERTY)
   default:
     // All machine specific PT_* types
     switch (Arch) {