to improve scalability of operations on the map.
originally done by Niels Provos for OpenBSD.
tweaked for NetBSD by me with some advices from enami tsugutomo.
discussed on tech-kern@ and tech-perform@.
tearing down a vm_map. use this to skip the pmap_update()
at the end of all the removes, which allows pmaps to optimize
pmap tear-down. also, use the new pmap_remove_all() hook to
let the pmap implemenation know what we're up to.
an spl-protected "interrupt safe map" list, simply require that callers
of uvm_fault() never call us in interrupt context (MD code must make
the assertion), and check for interrupt-safe maps in uvmfault_lookup()
before we lock the map.
set up quite a few regular ones (at every fork!), so put interrupt-
safe map setup in the slow path with a __predict_false().
uvm_map_reference(): __predict_false() the check for NULL map.
uvm_map_deallocate(): Likewise.
looking up a kernel address, check to see if the address is on this
"interrupt-safe" list. If so, return failure immediately. This prevents
a locking screw if a page fault is taken on an interrupt-safe map in or
out of interrupt context.
has PAGEABLE and INTRSAFE flags. PAGEABLE now really means "pageable",
not "allocate vm_map_entry's from non-static pool", so update all map
creations to reflect that. INTRSAFE maps are maps that are used in
interrupt context (e.g. kmem_map, mb_map), and thus use the static
map entry pool (XXX as does kernel_map, for now). This will eventually
change now these maps are locked, as well.
- replace map checks with submap checks
- get rid of unused 'mainonly' arg in uvm_unmap/uvm_unmap_remove, simplify
code. update all calls to reflect this.
- don't worry about unmapping or changing the protection of shared share
map mappings (is_main_map no longer used).
- remove unused uvm_map_sharemapcopy() function from fork code.
UVM was written by chuck cranor <chuck@maria.wustl.edu>, with some
minor portions derived from the old Mach code. i provided some help
getting swap and paging working, and other bug fixes/ideas. chuck
silvers <chuq@chuq.com> also provided some other fixes.
this is the UVM kernel code portion.
this will be KNF'd shortly. :-)
