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Subject: Re: RFC: userspace exception fixups
From:   Sean Christopherson <sean.j.christopherson@intel.com>
To:     Andy Lutomirski <luto@amacapital.net>
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On Tue, 2018-11-06 at 08:57 -0800, Andy Lutomirski wrote:
>
> So I guess the non-enclave code basically can’t trust its stack pointer
> because of these shenanigans. And the AEP code has to live with the fact
> that its RSP is basically arbitrary and probably can’t even be unwound
> by a debugger?

The SDK provides a Python GDB plugin to hook into the out-call flow and
do more stack shenanigans.  From what I can tell it's fudging the stack
to make it look like a normal stack frame so the debugger can do it's
thing.

> And the EENTER code has to deal with the fact that its red zone can be
> blatantly violated by the enclave?

That's my understanding of things.  So yeah, if it wasn't obvious before,
the trusted and untrusted parts of the SDK are very tightly coupled.