On 05/03/2018 06:05 AM, Andy Lutomirski wrote:
On Wed, May 2, 2018 at 7:11 PM Ram Pai <linuxram@xxxxxxxxxx> wrote:
On Wed, May 02, 2018 at 09:23:49PM +0000, Andy Lutomirski wrote:
If I recall correctly, the POWER maintainer did express a strong
desire
back then for (what is, I believe) their current semantics, which my
PKEY_ALLOC_SIGNALINHERIT patch implements for x86, too.
Ram, I really really don't like the POWER semantics. Can you give some
justification for them? Does POWER at least have an atomic way for
userspace to modify just the key it wants to modify or, even better,
special load and store instructions to use alternate keys?
I wouldn't call it POWER semantics. The way I implemented it on power
lead to the semantics, given that nothing was explicitly stated
about how the semantics should work within a signal handler.
I think that this is further evidence that we should introduce a new
pkey_alloc() mode and deprecate the old. To the extent possible, this
thing should work the same way on x86 and POWER.
Do you propose to change POWER or to change x86?
Thanks,
Florian
