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List:       linux-api
Subject:    Re: RFC: userspace exception fixups
From:       Jarkko Sakkinen <jarkko.sakkinen () linux ! intel ! com>
Date:       2018-11-26 22:06:27
Message-ID: 20181126220627.GD868 () linux ! intel ! com
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On Mon, Nov 26, 2018 at 06:35:34AM -0800, Sean Christopherson wrote:
> And how would you determine the #UD is related to SGX?  Hardware doesn't
> provide any indication that a #UD (or any other fault) is related to SGX
> or occurred in an enclave.  The only fault that is special-cased in a
> non-virtualized environment is #PF signaled by the EPCM, which gets the
> PF_SGX bit set in the error code.

Could you not detect #UD from address where it happened? Kernel knows
where enclaves are mapped. BTW, how does Intel run-time emulate opcodes
currently?

Anyway, I've fully discarded the whole idea because implementing single
stepping w/o well defined AEP handler is nasty. I think vDSO's are the
only viable path that at least I'm aware off...

/Jarkko
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