On 2018-11-07 02:17, Andy Lutomirski wrote:
> On Tue, Nov 6, 2018 at 4:02 PM Sean Christopherson
> <sean.j.christopherson@intel.com> wrote:
>>
>> /*
>>   * EEXIT or EENTER faulted.  In the latter case, %RAX already holds some
>>   * fault indicator, e.g. -EFAULT.
>>   */
>> eexit_or_eenter_fault:
>>      ret
> 
> But userspace wants to know whether it was a fault or not.  So I think
> we either need two landing pads or we need to hijack a flag bit (are
> there any known-zeroed flag bits after EEXIT?) to say whether it was a
> fault.  And, if it was a fault, we should give the vector, the
> sanitized error code, and possibly CR2.

On AEX, %rax will contain ENCLU_LEAF_ERESUME (0x3). On EEXIT, %rax will 
contain ENCLU_LEAF_EEXIT (0x4).

--
Jethro Beekman | Fortanix