[llvm] [llvm][llvm-readobj] Add NT_ARM_GCS Linux core note type (PR #117545)

[David Spickett via llvm-commits]

https://github.com/DavidSpickett created https://github.com/llvm/llvm-project/pull/117545

The ARM Guarded Control Stack extension (GCS) is similar to existing shadow stack extensions for other architectures.

The core note will include which features of GCS are enabled, which have been locked in their current state, and the stack pointer of the shadow stack.

Note that 0x40f is NT_ARM_POE, FPMR and GCS will be supported by lldb, POE is not at this time.

>From 43d2af5d36904efcf336bcdd3ef0105c03b79b55 Mon Sep 17 00:00:00 2001
From: David Spickett <david.spickett at linaro.org>
Date: Tue, 6 Aug 2024 15:48:53 +0100
Subject: [PATCH] [llvm][llvm-readobj] Add NT_ARM_GCS Linux core note type

The ARM Guarded Control Stack extension (GCS) is similar to existing
shadow stack extensions for other architectures.

The core note will include which features of GCS are enabled,
which have been locked in their current state, and the stack
pointer of the shadow stack.

Note that 0x40f is NT_ARM_POE, FPMR and GCS will be supported
by lldb, POE is not at this time.
---
 llvm/include/llvm/BinaryFormat/ELF.h            | 1 +
 llvm/lib/ObjectYAML/ELFYAML.cpp                 | 1 +
 llvm/test/tools/llvm-readobj/ELF/note-core.test | 5 +++++
 llvm/tools/llvm-readobj/ELFDumper.cpp           | 1 +
 4 files changed, 8 insertions(+)

diff --git a/llvm/include/llvm/BinaryFormat/ELF.h b/llvm/include/llvm/BinaryFormat/ELF.h
index fd32a6ec19652b..5356843f8ecf1a 100644
--- a/llvm/include/llvm/BinaryFormat/ELF.h
+++ b/llvm/include/llvm/BinaryFormat/ELF.h
@@ -1724,6 +1724,7 @@ enum : unsigned {
   NT_ARM_ZA = 0x40c,
   NT_ARM_ZT = 0x40d,
   NT_ARM_FPMR = 0x40e,
+  NT_ARM_GCS = 0x410,
 
   NT_FILE = 0x46494c45,
   NT_PRXFPREG = 0x46e62b7f,
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index ca0ea03452d3be..f28e6766f734c0 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -136,6 +136,7 @@ void ScalarEnumerationTraits<ELFYAML::ELF_NT>::enumeration(
   ECase(NT_ARM_ZA);
   ECase(NT_ARM_ZT);
   ECase(NT_ARM_FPMR);
+  ECase(NT_ARM_GCS);
   ECase(NT_FILE);
   ECase(NT_PRXFPREG);
   ECase(NT_SIGINFO);
diff --git a/llvm/test/tools/llvm-readobj/ELF/note-core.test b/llvm/test/tools/llvm-readobj/ELF/note-core.test
index 1196d4b2507241..2c35178a97524b 100644
--- a/llvm/test/tools/llvm-readobj/ELF/note-core.test
+++ b/llvm/test/tools/llvm-readobj/ELF/note-core.test
@@ -265,6 +265,11 @@
 # RUN: llvm-readelf --notes %t_nt_arm_fpmr.o | FileCheck %s --check-prefix=CHECK-GNU  -DDESC="NT_ARM_FPMR (AArch64 Floating Point Mode Register)"
 # RUN: llvm-readobj --notes %t_nt_arm_fpmr.o | FileCheck %s --check-prefix=CHECK-LLVM -DDESC="NT_ARM_FPMR (AArch64 Floating Point Mode Register)"
 
+## Check ELF::NT_ARM_GCS
+# RUN: yaml2obj %s -DTYPE=0x410 -o %t_nt_arm_gcs.o
+# RUN: llvm-readelf --notes %t_nt_arm_gcs.o | FileCheck %s --check-prefix=CHECK-GNU  -DDESC="NT_ARM_GCS (AArch64 Guarded Control Stack state)"
+# RUN: llvm-readobj --notes %t_nt_arm_gcs.o | FileCheck %s --check-prefix=CHECK-LLVM -DDESC="NT_ARM_GCS (AArch64 Guarded Control Stack state)"
+
 ## Check ELF::NT_FILE.
 # RUN: yaml2obj %s -DTYPE=0x46494c45 -o %t_nt_file.o
 # RUN: llvm-readelf --notes %t_nt_file.o | FileCheck %s --check-prefix=CHECK-GNU  -DDESC="NT_FILE (mapped files)"
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index bb8ec41d87454c..bfca65aad52b44 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -6057,6 +6057,7 @@ const NoteType CoreNoteTypes[] = {
     {ELF::NT_ARM_ZA, "NT_ARM_ZA (AArch64 SME ZA registers)"},
     {ELF::NT_ARM_ZT, "NT_ARM_ZT (AArch64 SME ZT registers)"},
     {ELF::NT_ARM_FPMR, "NT_ARM_FPMR (AArch64 Floating Point Mode Register)"},
+    {ELF::NT_ARM_GCS, "NT_ARM_GCS (AArch64 Guarded Control Stack state)"},
 
     {ELF::NT_FILE, "NT_FILE (mapped files)"},
     {ELF::NT_PRXFPREG, "NT_PRXFPREG (user_xfpregs structure)"},