[llvm-readobj] Add support for reading OpenBSD ELF core notes.

[fcambus]

Summary

Notes generated in OpenBSD core files provide additional information about the kernel state and CPU registers. These notes are described in core.5, which can be viewed here: https://man.openbsd.org/core.5

[MaskRay]

llvm/include/llvm/BinaryFormat/ELF.h

1614

one blank line

llvm/tools/llvm-readobj/ELFDumper.cpp

5334

By default a non-template variable of non-volatile const-qualified type belong to a namespace scope is internal, so static const can usually be written as const.

I simplified other variables.

5454

startswith("OpenBSD") If I understand it correctly

[MaskRay]

Thanks!

llvm/tools/llvm-readobj/ELFDumper.cpp

5455

The two if can be combined

[fcambus]

Combine the two if checks in getNoteTypeName().

llvm/include/llvm/BinaryFormat/ELF.h

enum {
   NT_FREEBSD_PROCSTAT_GROUPS = 11,
   NT_FREEBSD_PROCSTAT_UMASK = 12,
   NT_FREEBSD_PROCSTAT_RLIMIT = 13,
   NT_FREEBSD_PROCSTAT_OSREL = 14,
   NT_FREEBSD_PROCSTAT_PSSTRINGS = 15,
   NT_FREEBSD_PROCSTAT_AUXV = 16,
 };
 
+// OpenBSD core note types.
+enum {
+  NT_OPENBSD_PROCINFO = 10,
+  NT_OPENBSD_AUXV = 11,
+  NT_OPENBSD_REGS = 20,
+  NT_OPENBSD_FPREGS = 21,
+  NT_OPENBSD_XFPREGS = 22,
+  NT_OPENBSD_WCOOKIE = 23,
+};
+
 // AMDGPU-specific section indices.
 enum {
   SHN_AMDGPU_LDS = 0xff00, // Variable in LDS; symbol encoded like SHN_COMMON
 };
 
 // AMD vendor specific notes. (Code Object V2)
 enum {
   NT_AMD_HSA_CODE_OBJECT_VERSION = 1,

llvm/lib/ObjectYAML/ELFYAML.cpp

#define ECase(X) IO.enumCase(Value, #X, ELF::X)
   ECase(NT_FREEBSD_PROCSTAT_FILES);
   ECase(NT_FREEBSD_PROCSTAT_VMMAP);
   ECase(NT_FREEBSD_PROCSTAT_GROUPS);
   ECase(NT_FREEBSD_PROCSTAT_UMASK);
   ECase(NT_FREEBSD_PROCSTAT_RLIMIT);
   ECase(NT_FREEBSD_PROCSTAT_OSREL);
   ECase(NT_FREEBSD_PROCSTAT_PSSTRINGS);
   ECase(NT_FREEBSD_PROCSTAT_AUXV);
+  // OpenBSD core note types.
+  ECase(NT_OPENBSD_PROCINFO);
+  ECase(NT_OPENBSD_AUXV);
+  ECase(NT_OPENBSD_REGS);
+  ECase(NT_OPENBSD_FPREGS);
+  ECase(NT_OPENBSD_XFPREGS);
+  ECase(NT_OPENBSD_WCOOKIE);
   // AMD specific notes. (Code Object V2)
   ECase(NT_AMD_HSA_CODE_OBJECT_VERSION);
   ECase(NT_AMD_HSA_HSAIL);
   ECase(NT_AMD_HSA_ISA_VERSION);
   ECase(NT_AMD_HSA_METADATA);
   ECase(NT_AMD_HSA_ISA_NAME);
   ECase(NT_AMD_PAL_METADATA);
   // AMDGPU specific notes. (Code Object V3)

llvm/test/tools/llvm-readobj/ELF/note-openbsd-core.test

+## Test that note values are interpreted correctly for OpenBSD core files.
+# RUN: yaml2obj %s -o %t.o
+# RUN: llvm-readelf --notes %t.o | FileCheck %s --check-prefix=GNU --strict-whitespace
+# RUN: llvm-readobj --notes %t.o | FileCheck %s --check-prefix=LLVM --strict-whitespace
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_CORE
+Sections:
+  - Name: .note.foo
+    Type: SHT_NOTE
+    Notes:
+      - Name: OpenBSD
+        Type: NT_OPENBSD_PROCINFO
+      - Name: OpenBSD
+        Type: NT_OPENBSD_AUXV
+      - Name: OpenBSD
+        Type: NT_OPENBSD_WCOOKIE
+      - Name: OpenBSD@31337
+        Type: NT_OPENBSD_REGS
+      - Name: OpenBSD@31337
+        Type: NT_OPENBSD_FPREGS
+ProgramHeaders:
+  - Type:     PT_NOTE
+    FirstSec: .note.foo
+    LastSec:  .note.foo
+
+# GNU:      Displaying notes found at file offset 0x00000078 with length 0x00000074:
+# GNU-NEXT:   Owner                Data size  Description
+# GNU-NEXT:   OpenBSD              0x00000000 NT_OPENBSD_PROCINFO (procinfo structure)
+# GNU-NEXT:   OpenBSD              0x00000000 NT_OPENBSD_AUXV (ELF auxiliary vector data)
+# GNU-NEXT:   OpenBSD              0x00000000 NT_OPENBSD_WCOOKIE (window cookie)
+# GNU-NEXT:   OpenBSD@31337        0x00000000 NT_OPENBSD_REGS (regular registers)
+# GNU-NEXT:   OpenBSD@31337        0x00000000 NT_OPENBSD_FPREGS (floating point registers)
+
+# LLVM:      Notes [
+# LLVM-NEXT:   NoteSection {
+# LLVM-NEXT:     Name: <?>
+# LLVM-NEXT:     Offset: 0x78
+# LLVM-NEXT:     Size: 0x74
+# LLVM-NEXT:     Note {
+# LLVM-NEXT:       Owner: OpenBSD
+# LLVM-NEXT:       Data size: 0x0
+# LLVM-NEXT:       Type: NT_OPENBSD_PROCINFO (procinfo structure)
+# LLVM-NEXT:     }
+# LLVM-NEXT:     Note {
+# LLVM-NEXT:       Owner: OpenBSD
+# LLVM-NEXT:       Data size: 0x0
+# LLVM-NEXT:       Type: NT_OPENBSD_AUXV (ELF auxiliary vector data)
+# LLVM-NEXT:     }
+# LLVM-NEXT:     Note {
+# LLVM-NEXT:       Owner: OpenBSD
+# LLVM-NEXT:       Data size: 0x0
+# LLVM-NEXT:       Type: NT_OPENBSD_WCOOKIE (window cookie)
+# LLVM-NEXT:     }
+# LLVM-NEXT:     Note {
+# LLVM-NEXT:       Owner: OpenBSD@31337
+# LLVM-NEXT:       Data size: 0x0
+# LLVM-NEXT:       Type: NT_OPENBSD_REGS (regular registers)
+# LLVM-NEXT:     }
+# LLVM-NEXT:     Note {
+# LLVM-NEXT:       Owner: OpenBSD@31337
+# LLVM-NEXT:       Data size: 0x0
+# LLVM-NEXT:       Type: NT_OPENBSD_FPREGS (floating point registers)
+# LLVM-NEXT:     }
+# LLVM-NEXT:   }
+# LLVM-NEXT: ]

llvm/tools/llvm-readobj/ELFDumper.cpp

 const NoteType FreeBSDNoteTypes[] = {
     {ELF::NT_FREEBSD_ABI_TAG, "NT_FREEBSD_ABI_TAG (ABI version tag)"},
     {ELF::NT_FREEBSD_NOINIT_TAG, "NT_FREEBSD_NOINIT_TAG (no .init tag)"},
     {ELF::NT_FREEBSD_ARCH_TAG, "NT_FREEBSD_ARCH_TAG (architecture tag)"},
     {ELF::NT_FREEBSD_FEATURE_CTL,
      "NT_FREEBSD_FEATURE_CTL (FreeBSD feature control)"},
 };
 
+const NoteType OpenBSDCoreNoteTypes[] = {
+    {ELF::NT_OPENBSD_PROCINFO, "NT_OPENBSD_PROCINFO (procinfo structure)"},
+    {ELF::NT_OPENBSD_AUXV, "NT_OPENBSD_AUXV (ELF auxiliary vector data)"},
+    {ELF::NT_OPENBSD_REGS, "NT_OPENBSD_REGS (regular registers)"},
+    {ELF::NT_OPENBSD_FPREGS, "NT_OPENBSD_FPREGS (floating point registers)"},
+    {ELF::NT_OPENBSD_WCOOKIE, "NT_OPENBSD_WCOOKIE (window cookie)"},
+};
+
 const NoteType AMDNoteTypes[] = {
     {ELF::NT_AMD_HSA_CODE_OBJECT_VERSION,
      "NT_AMD_HSA_CODE_OBJECT_VERSION (AMD HSA Code Object Version)"},
     {ELF::NT_AMD_HSA_HSAIL, "NT_AMD_HSA_HSAIL (AMD HSA HSAIL Properties)"},
     {ELF::NT_AMD_HSA_ISA_VERSION, "NT_AMD_HSA_ISA_VERSION (AMD HSA ISA Version)"},
     {ELF::NT_AMD_HSA_METADATA, "NT_AMD_HSA_METADATA (AMD HSA Metadata)"},
     {ELF::NT_AMD_HSA_ISA_NAME, "NT_AMD_HSA_ISA_NAME (AMD HSA ISA Name)"},
     {ELF::NT_AMD_PAL_METADATA, "NT_AMD_PAL_METADATA (AMD PAL Metadata)"},
if (ELFType == ELF::ET_CORE) {
       StringRef Result = FindNote(FreeBSDCoreNoteTypes);
       if (!Result.empty())
         return Result;
       return FindNote(CoreNoteTypes);
     } else {
       return FindNote(FreeBSDNoteTypes);
     }
   }
+  if (Name.startswith("OpenBSD") && ELFType == ELF::ET_CORE) {
+    // OpenBSD also places the generic core notes in the OpenBSD namespace.
+    StringRef Result = FindNote(OpenBSDCoreNoteTypes);
+    if (!Result.empty())
+      return Result;
+    return FindNote(CoreNoteTypes);
+  }
   if (Name == "AMD")
     return FindNote(AMDNoteTypes);
   if (Name == "AMDGPU")
     return FindNote(AMDGPUNoteTypes);
   if (Name == "LLVMOMPOFFLOAD")
     return FindNote(LLVMOMPOFFLOADNoteTypes);
 
   if (ELFType == ELF::ET_CORE)