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

From: Jarkko Sakkinen
Date: Tue Dec 18 2018 - 23:43:55 EST


On Tue, Dec 18, 2018 at 07:08:15AM -0800, Sean Christopherson wrote:
> On Tue, Dec 18, 2018 at 06:18:15AM +0200, Jarkko Sakkinen wrote:
> > 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?
>
> Patch 5/5 has more details, and v4 of the series has a lot of background
> info by way of discussion:
>
> https://lkml.kernel.org/r/20181213213135.12913-1-sean.j.christopherson@xxxxxxxxx

Thanks Sean, I will. Have not had yet much time to look at this.

/Jarkko