Re: [PATCH v10 01/26] Documentation/x86: Add CET description

[Yu-cheng Yu]

On Wed, 2020-04-29 at 15:53 -0700, Dave Hansen wrote:
> On 4/29/20 3:07 PM, Yu-cheng Yu wrote:
> > +Note:
> > +  There is no CET-enabling arch_prctl function.  By design, CET is enabled
> > +  automatically if the binary and the system can support it.
> 
> I think Andy and I danced around this last time.  Let me try to say it
> more explicitly.
> 
> I want CET kernel enabling to able to be disconnected from the on-disk
> binary.  I want a binary compiled with CET to be able to disable it, and
> I want a binary not compiled with CET to be able to enable it.  I want
> different threads in a process to be able to each have different CET status.

The kernel patches we have now can be modified to support this model.  If after
discussion this is favorable, I will modify code accordingly.

> Which JITs was this tested with?  I think as a bare minimum we need to
> know that this design can accommodate _a_ modern JIT.  It would be
> horrible if the browser javascript engines couldn't use this design, for
> instance.

JIT work is still in progress.  When that is available I will test it.

Yu-cheng