Russell King - ARM Linux <li...@armlinux.org.uk> writes: > On Thu, May 10, 2018 at 01:39:18PM -0600, Mathieu Poirier wrote: >> Hi Russell, >> >> On 10 May 2018 at 02:40, Russell King - ARM Linux <li...@armlinux.org.uk> >> wrote: >> > This does not leak information from other namespaces because of the >> > uniqueness of the global PID. However, what it does leak is the value >> > of the global PID which is meaningless in the namespace. So, before >> > the event stream is delivered to userspace, this value needs to be >> > re-written to the namespace's PID value. >> >> Unfortunately that can't be done. The trace stream is compressed and >> needs to be decompressed using an external library. I think the only >> option is to return an error if a user is trying to use this feature >> from a namespace. > > That sounds like a sensible approach, and that should get rid of the > vpid stuff too. > > Eric, would this solve all your concerns?
It does, and I have given my ack to the respin. I am moderately concerned about using the global pid with hardware. But pids are a core abstraction that aren't going anywhere. As long as hardware does not impose constraints on pids that software already does not we should be fine. Eric
