On 09/26/2018 02:15 PM, Andy Lutomirski wrote: > Could we perhaps have a little vDSO entry (or syscall, I suppose) that > 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?
Yeah, signals suck. So, instead of doing the enclave entry instruction (EENTER is it?), the app would do the vDSO call. It would have some calling convention, like "set %rax to 0 before entering". Then, we just teach the page fault handler about the %RIP in the vDSO that can fault and how to move one instruction later, munge %RIP to a value that tells about the error, then return from the fault. It would basically be like the kernel exception tables, but for userspace. Right? How would a syscall work, though? I assume we can't just enter the enclave from ring0.
