K 10
svn:author
V 3
alc
K 8
svn:date
V 27
2018-08-08T16:55:01.811029Z
K 7
svn:log
V 1293
Add support for pmap_enter(..., psind=1) to the armv6 pmap.  In other words,
add support for explicitly requesting that pmap_enter() create a 1 MB page
mapping.  (Essentially, this feature allows the machine-independent layer
to create superpage mappings preemptively, and not wait for automatic
promotion to occur.)

Export pmap_ps_enabled() to the machine-independent layer.

Add a flag to pmap_pv_insert_pte1() that specifies whether it should fail
or reclaim a PV entry when one is not available.

Refactor pmap_enter_pte1() into two functions, one by the same name, that
is a general-purpose function for creating pte1 mappings, and another,
pmap_enter_1mpage(), that is used to prefault 1 MB read- and/or execute-
only mappings for execve(2), mmap(2), and shmat(2).

In addition, as an optimization to pmap_enter(..., psind=0), eliminate the
use of pte2_is_managed() from pmap_enter().  Unlike the x86 pmap
implementations, armv6 does not have a managed bit defined within the PTE.
So, pte2_is_managed() is actually a call to PHYS_TO_VM_PAGE(), which is O(n)
in the number of vm_phys_segs[].  All but one call to PHYS_TO_VM_PAGE() in
pmap_enter() can be avoided.

Reviewed by:	kib, markj, mmel
Tested by:	mmel
MFC after:	6 weeks
Differential Revision:	https://reviews.freebsd.org/D16555

END