On 10/03/2015 12:27 AM, Ingo Molnar wrote:
> - I'd also suggest providing an initial value with the 'alloc' call. It's
> true
> that user-space can do this itself in assembly, OTOH there's no reason not
> to
> provide a C interface for this.
You mean an initial value for the rights register (PKRU), correct?
So init_val would be something like
PKEY_DENY_ACCESS
PKEY_DENY_WRITE
and it would refer only to the key that was allocated.
> - Along similar considerations, also add a sys_pkey_query() system call to
> query
> the mapping of a specific pkey. (returns -EBADF or so if the key is not
> mapped
> at the moment.) This too could be vDSO accelerated in the future.
Do you mean whether the key is being used on a mapping (VMA) or rather
whether the key is currently allocated (has been returned from
sys_pkey_alloc() in the past)?
> I.e. something like:
>
> unsigned long sys_pkey_alloc (unsigned long flags, unsigned long
> init_val)
> unsigned long sys_pkey_set (int pkey, unsigned long new_val)
> unsigned long sys_pkey_get (int pkey)
> unsigned long sys_pkey_free (int pkey)
>
> Optional suggestion:
>
> - _Maybe_ also allow the 'remote managed' setup of pkeys: of non-local tasks
> -
> but I'm not sure about that: it looks expensive and complex, and a TID
> argument
> can always be added later if there's some real need.
Yeah, let's see how the stuff above looks first.
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