Re: [PATCH v14 09/19] x86/mm: x86/sgx: Signal SEGV_SGXERR for #PFs w/ PF_SGX

[Jarkko Sakkinen]

On Mon, Oct 01, 2018 at 07:29:03AM -0700, Sean Christopherson wrote:
> On Wed, 2018-09-26 at 14:15 -0700, Andy Lutomirski wrote:
> > runs an enclave an returns an error code, and rig up the #PF handler
> > to check if the error happened in the vDSO entry and fix it up rather
> > than sending a signal?
> 
> 
> If we want to avoid having to install a signal handler then I'm pretty
> sure we'd need to fixup all #GPs and "bad access" #PFs that occur on
> EENTER or in the enclave, not just PF_SGX faults.  SGX1 hardware takes
> a #GP instead of a #PF on EPCM faults, and SGX2 hardware allows enclaves
> to allocate/free/adjust EPC pages at runtime, e.g. an enclave runtime
> might want to intercept #PFs from within the enclave so that the enclave
> can dynamically grow its stack.

If I've understood Andy's proposal correctly, the run-time would get the
same information as with a signal. The delivery path for this
information would be just different.

/Jarkko