[compiler-rt][libunwind] Allow for CET on OpenBSD (llvm#164341)

Author: brad0

compiler-rt/CMakeLists.txt

@@ -315,7 +315,7 @@ include(config-ix)
 # Setup Compiler Flags
 #================================
 
-# fcf-protection is a gcc/clang option for CET support on Linux platforms.
+# fcf-protection is a gcc/clang option for CET support on some ELF platforms.
 # We need to handle MSVC CET option on Windows platforms.
 if (NOT MSVC)
   if (COMPILER_RT_ENABLE_CET AND NOT COMPILER_RT_HAS_FCF_PROTECTION_FLAG)

compiler-rt/lib/builtins/assembly.h

@@ -14,7 +14,7 @@
 #ifndef COMPILERRT_ASSEMBLY_H
 #define COMPILERRT_ASSEMBLY_H
 
-#if defined(__linux__) && defined(__CET__)
+#ifdef __CET__
 #if __has_include(<cet.h>)
 #include <cet.h>
 #endif

libunwind/src/assembly.h

@@ -15,7 +15,7 @@
 #ifndef UNWIND_ASSEMBLY_H
 #define UNWIND_ASSEMBLY_H
 
-#if defined(__linux__) && defined(__CET__)
+#if defined(__CET__)
 #include <cet.h>
 #define _LIBUNWIND_CET_ENDBR _CET_ENDBR
 #else

libunwind/src/shadow_stack_unwind.h

@@ -12,8 +12,8 @@
 
 #include "libunwind.h"
 
-// Currently, CET is implemented on Linux x86 platforms.
-#if defined(_LIBUNWIND_TARGET_LINUX) && defined(__CET__) && defined(__SHSTK__)
+// Currently, CET is implemented on some ELF x86 platforms.
+#if defined(__CET__) && defined(__SHSTK__)
 #define _LIBUNWIND_USE_CET 1
 #endif