On 10/18/2018 06:28 AM, Thomas Gleixner wrote: > > So now the obvious question. set_dumpable() operates on tsk->mm. i.e. it's > a process wide operation. But arch_set_dumpable() operates on the task > itself. What about the other tasks of that process?
I missed this part. Fixing this is tricky as I don't see an easy way to reverse map mm back to all tasks that use the same mm to update their STIBP flags. One possible solution is to not use STIBP flag for non-dumpable processes. We check during context switch whether get_dumpable(prev) != get_dumpable(next) in addition to STIBP flag changes to update SPEC_CTRL MSR and IBPB. We will need to IPI all other CPUs to update their SPEC_CTRL MSR if they are using the mm that has dumpable property changes. Any better suggestions? Tim > > Thanks, > > tglx >
