Kernel: Add barebones GeneralAllocator for >4096B

kernel/CMakeLists.txt

@@ -26,6 +26,7 @@ set(KERNEL_SOURCES
 	kernel/InterruptController.cpp
 	kernel/kernel.cpp
 	kernel/Memory/FixedWidthAllocator.cpp
+	kernel/Memory/GeneralAllocator.cpp
 	kernel/Memory/Heap.cpp
 	kernel/Memory/kmalloc.cpp
 	kernel/Panic.cpp

kernel/arch/x86_64/MMU.cpp

@@ -312,7 +312,7 @@ namespace Kernel
 
 		// Find any free page page (except for page 0)
 		vaddr_t address = PAGE_SIZE;
-		while ((address << 48) == 0)
+		while ((address >> 48) == 0)
 		{
 			if (!(get_page_flags(address) & Flags::Present))
 				return address;
@@ -322,6 +322,27 @@ namespace Kernel
 		ASSERT_NOT_REACHED();
 	}
 
+	vaddr_t MMU::get_free_contiguous_pages(size_t page_count) const
+	{
+		for (vaddr_t address = PAGE_SIZE; !(address >> 48); address += PAGE_SIZE)
+		{
+			bool valid { true };
+			for (size_t page = 0; page < page_count; page++)
+			{
+				if (get_page_flags(address + page * PAGE_SIZE) & Flags::Present)
+				{
+					address += page;
+					valid = false;
+					break;
+				}
+			}
+			if (valid)
+				return address;
+		}
+
+		ASSERT_NOT_REACHED();
+	}
+
 	bool MMU::is_page_free(vaddr_t page) const
 	{
 		ASSERT(page % PAGE_SIZE == 0);

kernel/include/kernel/Memory/GeneralAllocator.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include <BAN/LinkedList.h>
+#include <kernel/Memory/Heap.h>
+#include <kernel/Memory/MMU.h>
+
+namespace Kernel
+{
+
+	class GeneralAllocator
+	{
+		BAN_NON_COPYABLE(GeneralAllocator);
+		BAN_NON_MOVABLE(GeneralAllocator);
+
+	public:
+		GeneralAllocator(MMU&);
+		~GeneralAllocator();
+
+		vaddr_t allocate(size_t);
+		bool deallocate(vaddr_t);
+
+	private:
+		struct Allocation
+		{
+			vaddr_t address { 0 };
+			BAN::Vector<paddr_t> pages;
+		};
+
+	private:
+		MMU& m_mmu;
+		BAN::LinkedList<Allocation> m_allocations;
+	};
+
+}

kernel/include/kernel/Memory/MMU.h

@@ -24,10 +24,10 @@ namespace Kernel
 		~MMU();
 
 		void identity_map_page(paddr_t, flags_t);
-		void identity_map_range(paddr_t, size_t, flags_t);
+		void identity_map_range(paddr_t, size_t bytes, flags_t);
 
 		void unmap_page(vaddr_t);
-		void unmap_range(vaddr_t, size_t);
+		void unmap_range(vaddr_t, size_t bytes);
 
 		void map_page_at(paddr_t, vaddr_t, flags_t);
 
@@ -35,10 +35,10 @@ namespace Kernel
 		flags_t get_page_flags(vaddr_t) const;
 
 		bool is_page_free(vaddr_t) const;
-		bool is_range_free(vaddr_t, size_t) const;
+		bool is_range_free(vaddr_t, size_t bytes) const;
 
 		vaddr_t get_free_page() const;
-		vaddr_t get_free_contiguous_pages(uint32_t) const;
+		vaddr_t get_free_contiguous_pages(size_t page_count) const;
 
 		void load();
 

kernel/include/kernel/Process.h

@@ -5,6 +5,7 @@
 #include <BAN/Vector.h>
 #include <kernel/FS/Inode.h>
 #include <kernel/Memory/FixedWidthAllocator.h>
+#include <kernel/Memory/GeneralAllocator.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Memory/MMU.h>
 #include <kernel/SpinLock.h>
@@ -95,6 +96,7 @@ namespace Kernel
 		BAN::Vector<Thread*> m_threads;
 
 		BAN::LinkedList<FixedWidthAllocator> m_fixed_width_allocators;
+		GeneralAllocator* m_general_allocator;
 
 		MMU* m_mmu { nullptr };
 		TTY* m_tty { nullptr };

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;
+	}
+
+}

kernel/kernel/Process.cpp

@@ -118,6 +118,7 @@ namespace Kernel
 	{
 		ASSERT(m_threads.empty());
 		ASSERT(m_fixed_width_allocators.empty());
+		ASSERT(m_general_allocator == nullptr);
 		if (m_mmu)
 		{
 			MMU::get().load();
@@ -152,6 +153,11 @@ namespace Kernel
 
 		// NOTE: We must clear allocators while the mmu is still alive
 		m_fixed_width_allocators.clear();
+		if (m_general_allocator)
+		{
+			delete m_general_allocator;
+			m_general_allocator = nullptr;
+		}
 
 		dprintln("process {} exit", pid());
 		s_process_lock.lock();
@@ -385,6 +391,8 @@ namespace Kernel
 
 	BAN::ErrorOr<void*> Process::allocate(size_t bytes)
 	{
+		vaddr_t address = 0;
+
 		if (bytes <= PAGE_SIZE)
 		{
 			// Do fixed width allocation
@@ -393,18 +401,40 @@ namespace Kernel
 
 			LockGuard _(m_lock);
 
-			for (auto& allocator : m_fixed_width_allocators)
-				if (allocator.allocation_size() == allocation_size && allocator.allocations() < allocator.max_allocations())
-					return (void*)allocator.allocate();
+			bool needs_new_allocator { true };
 
-			MUST(m_fixed_width_allocators.emplace_back(mmu(), allocation_size));
-			return (void*)m_fixed_width_allocators.back().allocate();
+			for (auto& allocator : m_fixed_width_allocators)
+			{
+				if (allocator.allocation_size() == allocation_size && allocator.allocations() < allocator.max_allocations())
+				{
+					address = allocator.allocate();
+					needs_new_allocator = false;
+				}
+			}
+
+			if (needs_new_allocator)
+			{
+				TRY(m_fixed_width_allocators.emplace_back(mmu(), allocation_size));
+				address = m_fixed_width_allocators.back().allocate();
+			}
 		}
 		else
 		{
-			// TODO: Do general allocation
+			LockGuard _(m_lock);
+
+			if (!m_general_allocator)
+			{
+				m_general_allocator = new GeneralAllocator(mmu());
+				if (m_general_allocator == nullptr)
 					return BAN::Error::from_errno(ENOMEM);
 			}
+
+			address = m_general_allocator->allocate(bytes);
+		}
+
+		if (address == 0)
+			return BAN::Error::from_errno(ENOMEM);
+		return (void*)address;
 	}
 
 	void Process::free(void* ptr)
@@ -422,6 +452,10 @@ namespace Kernel
 				return;
 			}
 		}
+
+		if (m_general_allocator && m_general_allocator->deallocate((vaddr_t)ptr))
+			return;
+
 		dwarnln("free called on pointer that was not allocated");	
 	}
 

userspace/test.c

@@ -1,7 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#define N 512
+#define N 1024
 
 int main()
 {