Kernel: Add barebones GeneralAllocator for >4096B

kernel/kernel/Memory/GeneralAllocator.cpp

@@ -0,0 +1,64 @@
+#include <kernel/Memory/GeneralAllocator.h>
+#include <kernel/Process.h>
+
+namespace Kernel
+{
+
+	GeneralAllocator::GeneralAllocator(MMU& mmu)
+		: m_mmu(mmu)
+	{ }
+
+	GeneralAllocator::~GeneralAllocator()
+	{
+		while (!m_allocations.empty())
+			deallocate(m_allocations.front().address);
+	}
+
+	vaddr_t GeneralAllocator::allocate(size_t bytes)
+	{
+		size_t needed_pages = BAN::Math::div_round_up<size_t>(bytes, PAGE_SIZE);
+
+		Allocation allocation;
+		if (allocation.pages.resize(needed_pages, 0).is_error())
+			return 0;
+
+		for (size_t i = 0; i < needed_pages; i++)
+		{
+			paddr_t paddr = Heap::get().take_free_page();
+			if (paddr == 0)
+			{
+				for (size_t j = 0; j < i; j++)
+					Heap::get().release_page(allocation.pages[j]);
+				return 0;
+			}
+			allocation.pages[i] = paddr;
+		}
+
+		allocation.address = m_mmu.get_free_contiguous_pages(needed_pages);
+		for (size_t i = 0; i < needed_pages; i++)
+			m_mmu.map_page_at(allocation.pages[i], allocation.address + i * PAGE_SIZE, MMU::Flags::UserSupervisor | MMU::Flags::ReadWrite | MMU::Flags::Present);
+
+		MUST(m_allocations.push_back(BAN::move(allocation)));
+		return allocation.address;
+	}
+
+	bool GeneralAllocator::deallocate(vaddr_t address)
+	{
+		for (auto it = m_allocations.begin(); it != m_allocations.end(); it++)
+		{
+			if (it->address != address)
+				continue;
+			
+			m_mmu.unmap_range(it->address, it->pages.size() * PAGE_SIZE);
+			for (auto paddr : it->pages)
+				Heap::get().release_page(paddr);
+
+			m_allocations.remove(it);
+
+			return true;
+		}
+
+		return false;
+	}
+
+}