Messages in this thread | | | From | Balbir Singh <> | Date | Fri, 16 Mar 2018 22:02:22 +1100 | Subject | Re: [PATCH v4] mm, pkey: treat pkey-0 special |
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On Fri, Mar 16, 2018 at 9:33 PM, Ram Pai <linuxram@us.ibm.com> wrote: > Applications need the ability to associate an address-range with some > key and latter revert to its initial default key. Pkey-0 comes close to > providing this function but falls short, because the current > implementation disallows applications to explicitly associate pkey-0 to > the address range. > > Clarify the semantics of pkey-0 and provide the corresponding > implementation. > > Pkey-0 is special with the following semantics. > (a) it is implicitly allocated and can never be freed. It always exists. > (b) it is the default key assigned to any address-range. > (c) it can be explicitly associated with any address-range. > > Tested on powerpc only. Could not test on x86.
Ram,
I was wondering if we should check the AMOR values on the ppc side to make sure that pkey0 is indeed available for use as default. I am still of the opinion that we should consider non-0 default pkey in the long run. I'm OK with the patches for now, but really 0 is not special except for it being the default bit values present in the PTE.
The patches themselves look OK to me
Balbir Singh.
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