> On Dec 10, 2018, at 3:24 PM, Josh Triplett <[email protected]> wrote:
>
>> On Mon, Dec 10, 2018 at 03:21:37PM -0800, Sean Christopherson wrote:
>> At that point I realized it's a hell of a lot easier to simply provide
>> an IOCTL via /dev/sgx that allows userspace to register a per-process
>> ENCLU exception handler. At a high level, the basic idea is the same
>> as the vDSO approach: provide a hardcoded fixup handler for ENCLU and
>> attempt to fixup select unhandled exceptions that occurred in user code.
>
> So, on the one hand, this is *absolutely* much cleaner than the VDSO
> approach. On the other hand, this is global process state and has some
> of the same problems as a signal handler as a result.
I liked the old version better for this reason and for another reason: while
this new one looks very very simple, it still has the hidden complexity that
the magic values written to registers in the event of an exception are very
much Linux specific.
OTOH, the old approach clobbered more regs than needed, but that’s a easy fix.
