Re: [PATCH v28 21/22] x86/vdso: Implement a vDSO for Intel SGX enclave call

[Sean Christopherson]

On Fri, Mar 13, 2020 at 12:07:55PM -0400, Nathaniel McCallum wrote:
> On Thu, Mar 12, 2020 at 8:52 PM Sean Christopherson
> <sean.j.christopherson@xxxxxxxxx> wrote:
> > FWIW, if the handler reaaaly wanted to pop off the stack, it could do so,
> > fixup the stack, and then re-call __vdso_sgx_enter_enclave() instead of
> > returning (to the original __vdso_sgx_enter_enclave()).
> 
> My understanding from the documentation issue above was that *if* you
> wanted to push parameters back on the stack during enclave exit, you
> would *have* to supply a handler so it could pop the parameters and
> reset the stack. Which is why restoring %rsp from %rbx didn't make
> sense to me.

Yep.