On Fri, 8 Jun 2018 12:44:53 +0200 Florian Weimer <fweimer@xxxxxxxxxx> wrote: > On 06/08/2018 12:15 PM, Michal Suchánek wrote: > > On Fri, 8 Jun 2018 07:53:51 +0200 > > Florian Weimer <fweimer@xxxxxxxxxx> wrote: > > > >> On 06/08/2018 04:34 AM, Ram Pai wrote: > >>>> > >>>> So the remaining question at this point is whether the Intel > >>>> behavior (default-deny instead of default-allow) is preferable. > >>> > >>> Florian, remind me what behavior needs to fixed? > >> > >> See the other thread. The Intel register equivalent to the AMR by > >> default disallows access to yet-unallocated keys, so that threads > >> which are created before key allocation do not magically gain > >> access to a key allocated by another thread. > >> > > > > That does not make any sense. The threads share the address space so > > they should also share the keys. > > > > Or in other words the keys are supposed to be acceleration of > > mprotect() so if mprotect() magically gives access to threads that > > did not call it so should pkey functions. If they cannot do that > > then they fail the primary purpose. > > That's not how protection keys work. The access rights are > thread-specific, so that you can change them locally, without > synchronization and expensive inter-node communication. > And the association of a key with part of the address space is thread-local as well? Thanks Michal
