On Wed, May 02, 2018 at 09:18:11PM +0000, Andy Lutomirski wrote: > On Wed, May 2, 2018 at 2:13 PM Ram Pai <linuxram@xxxxxxxxxx> wrote: > > > > > Ram, would you please comment? > > > on POWER the pkey behavior will remain the same at entry or at exit from > > the signal handler. For eg: if a key is read-disabled on entry into > > the signal handler, and gets read-enabled in the signal handler, than it > > will continue to be read-enabled on return from the signal handler. > > > In other words, changes to key permissions persist across signal > > boundaries. > > I don't know about POWER's ISA, but this is crappy behavior. If a thread > temporarily grants itself access to a restrictive memory key and then gets > a signal, the signal handler should *not* have access to that key. This is a new requirement that I was not aware off. Its not documented anywhere AFAICT. Regardless of how the ISA behaves, its still a kernel behavior that needs to be clearly defined. -- Ram Pai
