Align CoreCLR GS cookie protection with NativeAOT

src/coreclr/vm/CMakeLists.txt

@@ -17,6 +17,10 @@ include_directories(${CLR_SRC_NATIVE_DIR}/libs/Common)
 add_definitions(-DUNICODE)
 add_definitions(-D_UNICODE)
 
+if(NOT CLR_CMAKE_TARGET_APPLE AND NOT CLR_CMAKE_TARGET_ARCH_WASM AND NOT CLR_CMAKE_TARGET_OPENBSD)
+    add_definitions(-DFEATURE_READONLY_GS_COOKIE)
+endif()
+
 if(CLR_CMAKE_TARGET_ANDROID OR CLR_CMAKE_TARGET_OPENBSD)
     # OpenBSD's ld.so cannot resolve native TLS relocations in shared objects and has no
     # __tls_get_addr, so the runtime must use emulated TLS (like Android).

src/coreclr/vm/ceemain.cpp

@@ -470,6 +470,7 @@ void InitGSCookie()
 
     volatile GSCookie * pGSCookiePtr = GetProcessGSCookiePtr();
 
+#ifdef FEATURE_READONLY_GS_COOKIE
     // The GS cookie is stored in a read only data segment
     DWORD oldProtection;
     if(!ClrVirtualProtect((LPVOID)pGSCookiePtr, sizeof(GSCookie), PAGE_READWRITE, &oldProtection))
@@ -481,6 +482,7 @@ void InitGSCookie()
     // PAL layer is unable to extract old protection for regions that were not allocated using VirtualAlloc
     oldProtection = PAGE_READONLY;
 #endif // TARGET_UNIX
+#endif // FEATURE_READONLY_GS_COOKIE
 
 #ifndef TARGET_UNIX
     // The GSCookie cannot be in a writeable page
@@ -507,10 +509,12 @@ void InitGSCookie()
         val ++;
     *pGSCookiePtr = val;
 
+#ifdef FEATURE_READONLY_GS_COOKIE
     if(!ClrVirtualProtect((LPVOID)pGSCookiePtr, sizeof(GSCookie), oldProtection, &oldProtection))
     {
         ThrowLastError();
     }
+#endif // FEATURE_READONLY_GS_COOKIE
 }
 
 Volatile<BOOL> g_bIsGarbageCollectorFullyInitialized = FALSE;

src/coreclr/vm/vars.cpp

@@ -252,7 +252,11 @@ void OBJECTREF_EnumMemoryRegions(OBJECTREF ref)
 //
 // We need the following to be the compiler's notion of volatile.
 //
+#ifdef FEATURE_READONLY_GS_COOKIE
 extern "C" RAW_KEYWORD(volatile) const GSCookie s_gsCookie = 0;
+#else
+extern "C" RAW_KEYWORD(volatile) GSCookie s_gsCookie = 0;
+#endif
 
 #else
 __GlobalVal< GSCookie > s_gsCookie(&DacGlobals::dac__s_gsCookie);

src/coreclr/vm/vars.hpp

@@ -594,11 +594,16 @@ typedef DPTR(GSCookie) PTR_GSCookie;
 #endif
 
 #ifndef DACCESS_COMPILE
-// const is so that it gets placed in the .text section (which is read-only)
+#ifdef FEATURE_READONLY_GS_COOKIE
+
+// const places the cookie in a read-only data section.
 // volatile is so that accesses to it do not get optimized away because of the const
 //
 
 extern "C" RAW_KEYWORD(volatile) READONLY_ATTR const GSCookie s_gsCookie;
+#else
+extern "C" RAW_KEYWORD(volatile) GSCookie s_gsCookie;
+#endif // FEATURE_READONLY_GS_COOKIE
 
 inline
 GSCookie * GetProcessGSCookiePtr() { return  const_cast<GSCookie *>(&s_gsCookie); }