Re: [RFC PATCH v2 0/3] An alternative __vdso_sgx_enter_enclave() to allow enclave/host parameter passing using untrusted stack

[Xing, Cedric]

On 7/10/2019 3:46 PM, Jarkko Sakkinen wrote:
> On Wed, Jul 10, 2019 at 11:08:37AM -0700, Xing, Cedric wrote:
> > > With these conclusions I think the current vDSO API is sufficient for
> > > Linux.
> >
> > The new vDSO API is to support data exchange on stack. It has nothing to do
> > with debugging. BTW, the community has closed on this.
>
> And how that is useful?

There is a lengthy discussion on its usefulness so I don't want to 
repeat. In short, it allows using untrusted stack as a convenient method 
to exchange data with the enclave. It is currently being used by Intel's 
SGX SDK for e/o-calls parameters.

> > The CFI directives are for stack unwinding. They don't affect what the code
> > does so you can just treat them as NOPs if you don't understand what they
> > do. However, they are useful to not only debuggers but also exception
> > handling code. libunwind also has a setjmp()/longjmp() implementation based
> > on CFI directives.
>
> Of course I won't merge code of which usefulness I don't understand.

Sure.

Any other questions I can help with?

> /Jarkko