On Tue, Nov 20, 2018 at 2:11 AM Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote: > > On Mon, Nov 19, 2018 at 09:00:08AM -0800, Andy Lutomirski wrote: > > On Mon, Nov 19, 2018 at 8:02 AM Jarkko Sakkinen > > <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote: > > > > > > On Mon, Nov 19, 2018 at 07:29:36AM -0800, Andy Lutomirski wrote: > > > > 1. The kernel needs some way to know *when* to apply this fixup. > > > > Decoding the instruction stream and doing it to all exceptions that > > > > hit an ENCLU instruction seems like a poor design. > > > > > > I'm not sure why you would ever need to do any type of fixup as the idea > > > is to just return to AEP i.e. from chosen exceptions (EPCM, #UD) the AEP > > > would work the same way as for exceptions that the kernel can deal with > > > except filling the exception information to registers. > > > > Sure, but how does the kernel know when to do that and when to send a > > signal? I don't really like decoding the instruction stream to figure > > it out. > > Hmm... why you have to decode instruction stream to find that out? Would > just depend on exception type (#GP with EPCM, #UD). What is "#GP with EPCM"? We certainly don't want to react to #UD in general by mucking with some regs and retrying -- that will infinite loop and confuse everyone. I'm not even 100% convinced that decoding the insn stream is useful -- AEP can point to something that isn't ENCLU. IOW the kernel needs to know *when* to apply this special behavior. Sadly there is no bit in the exception frame that says "came from SGX".
