This patch move AddressSpace (the per-process memory manager) to using
the new atomic "place" APIs in RegionTree as well, just like we did for
MemoryManager in the previous commit.
This required updating quite a few places where VM allocation and
actually committing a Region object to the AddressSpace were separated
by other code.
All you have to do now is call into AddressSpace once and it'll take
care of everything for you.
Instead of first allocating the VM range, and then inserting a region
with that range into the MM region tree, we now do both things in a
single atomic operation:
- RegionTree::place_anywhere(Region&, size, alignment)
- RegionTree::place_specifically(Region&, address, size)
To reduce the number of things we do while locking the region tree,
we also require callers to provide a constructed Region object.
This patch ports MemoryManager to RegionTree as well. The biggest
difference between this and the userspace code is that kernel regions
are owned by extant OwnPtr<Region> objects spread around the kernel,
while userspace regions are owned by the AddressSpace itself.
For kernelspace, there are a couple of situations where we need to make
large VM reservations that never get backed by regular VMObjects
(for example the kernel image reservation, or the big kmalloc range.)
Since we can't make a VM reservation without a Region object anymore,
this patch adds a way to create unbacked Region objects that can be
used for this exact purpose. They have no internal VMObject.)
RegionTree holds an IntrusiveRedBlackTree of Region objects and vends a
set of APIs for allocating memory ranges.
It's used by AddressSpace at the moment, and will be used by MM soon.
