Re: [PATCH v2 2/6] powerpc/pkeys: Save the pkey registers before fork

On Tue, Jun 19, 2018 at 10:39:56PM +1000, Michael Ellerman wrote:

Ram Pai [off-list ref] writes:

quoted

When a thread forks the contents of AMR, IAMR, UAMOR registers in the
newly forked thread are not inherited.

Save the registers before forking, for content of those
registers to be automatically copied into the new thread.

CC: Michael Ellerman <mpe@ellerman.id.au>
CC: Florian Weimer <redacted>
CC: Andy Lutomirski <luto@kernel.org>
CC: Thiago Jung Bauermann <redacted>
Signed-off-by: Ram Pai <redacted>

Again this is an ABI change but we'll call it a bug fix I guess.

yes. the same defense here too. its a behaviorial change for the better.
Single threaded applications will not see any behaviorial change.
Multithreaded apps, which were unable to consume, the behavior will now be
able to do so.

I'll add:

  Fixes: cf43d3b26452 ("powerpc: Enable pkey subsystem")
  Cc: stable@vger.kernel.org # v4.16+

yes.  Thanks
RP