Intel® SGX SDK - Prolog/Epilog Hook Request

While creating an Intel® SGX enclave, an EDL file (Enclave Definition Language file) is used to describe an enclave's trusted and untrusted functions and types.  These functions are the interface for communication between the enclave and the untrusted application.  The EDL file is read by Edger8r tool provided by the Intel® SGX SDK to generate edge/wrapper routines, which makes relevant checks and copies that ought to happen prior to and after trusted and untrusted calls.

We would like to make a request to Intel® SGX SDK team to add a minor feature to their Edger8r tool to generate prolog and epilog logging to the generated edge routines.  This would obviously be for troubleshooting convenience and in debug environment.  This request is the equivalency of what Microsoft Visual Studio compiler already provides via /Gh (Enable _penter Hook Function) compiler option.

By making it easier to troubleshoot a potentially targeted area, it is true that we might inadvertently encourage more additions to that area, thus rendering it more vulnerable.  However, those being frivolous with the interface functions are unlikely to be conservative because of lack of convenience/features of this nature.  Thus we might as well make it easy for those with a need.  After all, it is requested/recommended for development environment only.

Currently, we can workaround the lack of such a feature by simply adding another layer of indirection to EDL function calls or we could fallback on Microsoft compiler provided _penter hook for the Edger8r generated files.  The former adds an unnecessary layer of indirection while the latter is transient with the Edger8r tool regenerating the files in question for every recompilation.  An addition to Edger8r tool to add prolog/epilog hook, ought to be simple enough while helping troubleshoot problems in this area all the more easier!