Re: [RFC PATCH v2 4/4] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions

[Sean Christopherson]

On Fri, Dec 07, 2018 at 12:16:59PM -0800, Andy Lutomirski wrote:
> 
> > On Dec 7, 2018, at 12:09 PM, Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote:
> > 
> > Speaking of preserving registers, the asm blob needs to mark RBX as
> > clobbered since it's modified for EEXIT.
> 
> Have fun with that.  The x86_32 compiler seems to really like having its
> PIC register preserved, and you may get some lovely compiler errors.

Tagentinally related, as-is the SGX vDSO is only compiled for x86_64
since CONFIG_SGX depends on CONFIG_X86_64.  Mapping the EPC in 32-bit
mode complicates things and no one is asking for SGX support on 32-bit
builds, so...