efi/libstub: zboot: Mark zboot EFI application as NX compatible

Now that the zboot loader will invoke the EFI memory attributes protocol
to remap the decompressed code and rodata as read-only/executable, we
can set the PE/COFF header flag that indicates to the firmware that the
application does not rely on writable memory being executable at the
same time.

Cc: <[email protected]> # v6.2+
Signed-off-by: Ard Biesheuvel <[email protected]>

Author: ardbiesheuvel

drivers/firmware/efi/libstub/zboot-header.S

@@ -63,7 +63,7 @@ __efistub_efi_zboot_header:
 	.long		.Lefi_header_end - .Ldoshdr
 	.long		0
 	.short		IMAGE_SUBSYSTEM_EFI_APPLICATION
-	.short		0
+	.short		IMAGE_DLL_CHARACTERISTICS_NX_COMPAT
 #ifdef CONFIG_64BIT
 	.quad		0, 0, 0, 0
 #else