[kernel] Move vm_space into kernel

The vm_space code should not have been in kutil, moving it to kernel.

src/kernel/vm_space.h

@@ -0,0 +1,73 @@
+#pragma once
+/// \file vm_range.h
+/// Structure for tracking a range of virtual memory addresses
+
+#include <stdint.h>
+#include "kutil/avl_tree.h"
+
+enum class vm_state : uint8_t {
+	unknown,
+	none,
+	reserved,
+	committed
+};
+
+struct vm_range
+{
+	uintptr_t address;
+	size_t size;
+	vm_state state;
+
+	inline uintptr_t end() const { return address + size; }
+	inline int64_t compare(const vm_range *other) const {
+		if (address > other->address) return -1;
+		else if (address < other->address) return 1;
+		else return 0;
+	}
+};
+
+/// Tracks a region of virtual memory address space
+class vm_space
+{
+public:
+	/// Default constructor. Define an empty range.
+	vm_space();
+
+	/// Constructor. Define a range of managed VM space.
+	/// \arg start       Starting address of the managed space
+	/// \arg size        Size of the managed space, in bytes
+	vm_space(uintptr_t start, size_t size);
+
+	/// Reserve a section of address space.
+	/// \arg start  Starting address of reservaion, or 0 for any address
+	/// \arg size   Size of reservation in bytes
+	/// \returns  The address of the reservation, or 0 on failure
+	uintptr_t reserve(uintptr_t start, size_t size);
+
+	/// Unreserve (and uncommit, if committed) a section of address space.
+	/// \arg start  Starting address of reservaion
+	/// \arg size   Size of reservation in bytes
+	void unreserve(uintptr_t start, size_t size);
+
+	/// Mark a section of address space as committed.
+	/// \arg start  Starting address of reservaion, or 0 for any address
+	/// \arg size   Size of reservation in bytes
+	/// \returns  The address of the reservation, or 0 on failure
+	uintptr_t commit(uintptr_t start, size_t size);
+
+	/// Check the state of the given address.
+	/// \arg addr  The address to check
+	/// \returns   The state of the memory if known, or 'unknown'
+	vm_state get(uintptr_t addr);
+
+private:
+	using node_type = kutil::avl_node<vm_range>;
+	using tree_type = kutil::avl_tree<vm_range>;
+
+	node_type * split_out(node_type* node, uintptr_t start, size_t size, vm_state state);
+	node_type * consolidate(node_type* needle);
+	node_type * find_empty(node_type* node, size_t size, vm_state state);
+
+	tree_type m_ranges;
+};
+