Re: [RFC PATCH v5 0/5] x86: Add vDSO exception fixup for SGX

[Jarkko Sakkinen]

On Fri, Dec 14, 2018 at 01:57:24PM -0800, Sean Christopherson wrote:
> __vdso_sgx_enter_enclave() gets another rewrite, this time to strip
> it down to the bare minimum and explicitly break compliance with the
> x86-64 ABI.  Feedback from v4 revealed that __vdso_sgx_enter_enclave()
> would need to save (a lot) more than just the non-volatile GPRs to be
> compliant with the x86-64 ABI, at which point breaking from the ABI
> completely became much more palatable.
> 
> The non-standard ABI also solves the question of "which GPRs should be
> marshalled to/from the enclave" by getting out of the way entirely and
> letting userspace have free reign (except for RSP, which has a big ol'
> DO NOT TOUCH sign on it).

Can you share a reference, or is this better documented in the
accompanied patches?

/Jarkko