Kernel: Implement new abstract MemoryRegion

MemoryBackedRegion now inherits from this and is used for private
anonymous mappigs. This will make shared mappings and file backed
mappings much easier to implement.

kernel/CMakeLists.txt

@@ -35,6 +35,8 @@ set(KERNEL_SOURCES
 	kernel/Memory/GeneralAllocator.cpp
 	kernel/Memory/Heap.cpp
 	kernel/Memory/kmalloc.cpp
+	kernel/Memory/MemoryBackedRegion.cpp
+	kernel/Memory/MemoryRegion.cpp
 	kernel/Memory/PhysicalRange.cpp
 	kernel/Memory/VirtualRange.cpp
 	kernel/Networking/E1000.cpp

kernel/include/kernel/Memory/MemoryBackedRegion.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <kernel/Memory/MemoryRegion.h>
+
+namespace Kernel
+{
+
+	class MemoryBackedRegion final : public MemoryRegion
+	{
+		BAN_NON_COPYABLE(MemoryBackedRegion);
+		BAN_NON_MOVABLE(MemoryBackedRegion);
+	
+	public:
+		static BAN::ErrorOr<BAN::UniqPtr<MemoryBackedRegion>> create(PageTable&, size_t size, AddressRange, Type, PageTable::flags_t);
+		~MemoryBackedRegion();
+
+		virtual BAN::ErrorOr<bool> allocate_page_containing(vaddr_t vaddr) override;
+
+		virtual BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> clone(PageTable& new_page_table) override;
+
+		// Copy data from buffer into this region
+		// This can fail if no memory is mapped and no free memory was available
+		BAN::ErrorOr<void> copy_data_to_region(size_t offset_into_region, const uint8_t* buffer, size_t buffer_size);
+
+	private:
+		MemoryBackedRegion(PageTable&, size_t size, Type, PageTable::flags_t);
+	};
+
+}

kernel/include/kernel/Memory/MemoryRegion.h

@@ -0,0 +1,59 @@
+#pragma once
+
+#include <BAN/UniqPtr.h>
+#include <kernel/Memory/PageTable.h>
+#include <kernel/Memory/Types.h>
+
+#include <stddef.h>
+
+namespace Kernel
+{
+
+	struct AddressRange
+	{
+		vaddr_t start;
+		vaddr_t end;
+	};
+
+	class MemoryRegion
+	{
+		BAN_NON_COPYABLE(MemoryRegion);
+		BAN_NON_MOVABLE(MemoryRegion);
+
+	public:
+		enum Type : uint8_t
+		{
+			PRIVATE,
+			SHARED
+		};
+
+	public:
+		virtual ~MemoryRegion();
+
+		bool contains(vaddr_t address) const;
+		bool contains_fully(vaddr_t address, size_t size) const;
+		bool overlaps(vaddr_t address, size_t size) const;
+
+		size_t size() const { return m_size; }
+		vaddr_t vaddr() const { return m_vaddr; }
+
+		// Returns error if no memory was available
+		// Returns true if page was succesfully allocated
+		// Returns false if page was already allocated
+		virtual BAN::ErrorOr<bool> allocate_page_containing(vaddr_t address) = 0;
+
+		virtual BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> clone(PageTable& new_page_table) = 0;
+	
+	protected:
+		MemoryRegion(PageTable&, size_t size, Type type, PageTable::flags_t flags);
+		BAN::ErrorOr<void> initialize(AddressRange);
+
+	protected:
+		PageTable& m_page_table;
+		const size_t m_size;
+		const Type m_type;
+		const PageTable::flags_t m_flags;
+		vaddr_t m_vaddr { 0 };
+	};
+
+}

kernel/include/kernel/Process.h

@@ -7,7 +7,7 @@
 #include <kernel/Credentials.h>
 #include <kernel/FS/Inode.h>
 #include <kernel/Memory/Heap.h>
-#include <kernel/Memory/VirtualRange.h>
+#include <kernel/Memory/MemoryRegion.h>
 #include <kernel/OpenFileDescriptorSet.h>
 #include <kernel/SpinLock.h>
 #include <kernel/Terminal/TTY.h>
@@ -174,7 +174,7 @@ namespace Kernel
 		OpenFileDescriptorSet m_open_file_descriptors;
 
 		BAN::UniqPtr<LibELF::LoadableELF> m_loadable_elf;
-		BAN::Vector<BAN::UniqPtr<VirtualRange>> m_mapped_ranges;
+		BAN::Vector<BAN::UniqPtr<MemoryRegion>> m_mapped_regions;
 
 		pid_t m_sid;
 		pid_t m_pgrp;

kernel/kernel/Memory/MemoryBackedRegion.cpp

@@ -0,0 +1,124 @@
+#include <kernel/Memory/Heap.h>
+#include <kernel/Memory/MemoryBackedRegion.h>
+#include <kernel/LockGuard.h>
+
+namespace Kernel
+{
+
+	BAN::ErrorOr<BAN::UniqPtr<MemoryBackedRegion>> MemoryBackedRegion::create(PageTable& page_table, size_t size, AddressRange address_range, Type type, PageTable::flags_t flags)
+	{
+		ASSERT(type == Type::PRIVATE);
+
+		auto* region_ptr = new MemoryBackedRegion(page_table, size, type, flags);
+		if (region_ptr == nullptr)
+			return BAN::Error::from_errno(ENOMEM);
+		auto region = BAN::UniqPtr<MemoryBackedRegion>::adopt(region_ptr);
+
+		TRY(region->initialize(address_range));
+
+		return region;
+	}
+
+	MemoryBackedRegion::MemoryBackedRegion(PageTable& page_table, size_t size, Type type, PageTable::flags_t flags)
+		: MemoryRegion(page_table, size, type, flags)
+	{
+	}
+
+	MemoryBackedRegion::~MemoryBackedRegion()
+	{
+		ASSERT(m_type == Type::PRIVATE);
+
+		size_t needed_pages = BAN::Math::div_round_up<size_t>(m_size, PAGE_SIZE);
+		for (size_t i = 0; i < needed_pages; i++)
+		{
+			paddr_t paddr = m_page_table.physical_address_of(m_vaddr + i * PAGE_SIZE);
+			if (paddr != 0)
+				Heap::get().release_page(paddr);
+		}
+	}
+
+	BAN::ErrorOr<bool> MemoryBackedRegion::allocate_page_containing(vaddr_t address)
+	{
+		ASSERT(m_type == Type::PRIVATE);
+
+		ASSERT(contains(address));
+
+		// Check if address is already mapped
+		vaddr_t vaddr = address & PAGE_ADDR_MASK;
+		if (m_page_table.physical_address_of(vaddr) != 0)
+			return false;
+		
+		// Map new physcial page to address
+		paddr_t paddr = Heap::get().take_free_page();
+		if (paddr == 0)
+			return BAN::Error::from_errno(ENOMEM);
+		m_page_table.map_page_at(paddr, vaddr, m_flags);
+
+		// Zero out the new page
+		if (&PageTable::current() == &m_page_table)
+			memset((void*)vaddr, 0x00, PAGE_SIZE);
+		else
+		{
+			LockGuard _(PageTable::current());
+			ASSERT(PageTable::current().is_page_free(0));
+
+			PageTable::current().map_page_at(paddr, 0, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
+			memset((void*)0, 0x00, PAGE_SIZE);
+			PageTable::current().unmap_page(0);
+		}
+
+		return true;
+	}
+
+	BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> MemoryBackedRegion::clone(PageTable& new_page_table)
+	{
+		ASSERT(&PageTable::current() == &m_page_table);
+
+		auto result = TRY(MemoryBackedRegion::create(new_page_table, m_size, { .start = m_vaddr, .end = m_vaddr + m_size }, m_type, m_flags));
+
+		for (size_t offset = 0; offset < m_size; offset += PAGE_SIZE)
+		{
+			paddr_t paddr = m_page_table.physical_address_of(m_vaddr + offset);
+			if (paddr == 0)
+				continue;
+			TRY(result->copy_data_to_region(offset, (const uint8_t*)(m_vaddr + offset), PAGE_SIZE));
+		}
+		
+		return BAN::UniqPtr<MemoryRegion>(BAN::move(result));
+	}
+
+	BAN::ErrorOr<void> MemoryBackedRegion::copy_data_to_region(size_t offset_into_region, const uint8_t* buffer, size_t buffer_size)
+	{
+		ASSERT(offset_into_region + buffer_size <= m_size);
+
+		size_t written = 0;
+		while (written < buffer_size)
+		{
+			vaddr_t write_vaddr = m_vaddr + offset_into_region + written;
+			vaddr_t page_offset = write_vaddr % PAGE_SIZE;
+			size_t bytes = BAN::Math::min<size_t>(buffer_size - written, PAGE_SIZE - page_offset);
+
+			TRY(allocate_page_containing(write_vaddr));
+
+			if (&PageTable::current() == &m_page_table)
+				memcpy((void*)write_vaddr, (void*)(buffer + written), bytes);
+			else
+			{
+				paddr_t paddr = m_page_table.physical_address_of(write_vaddr & PAGE_ADDR_MASK);
+				ASSERT(paddr);
+
+				LockGuard _(PageTable::current());
+				ASSERT(PageTable::current().is_page_free(0));
+
+				PageTable::current().map_page_at(paddr, 0, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
+				memcpy((void*)page_offset, (void*)(buffer + written), bytes);
+				PageTable::current().unmap_page(0);
+			}
+
+			written += bytes;
+		}
+
+		return {};
+	}
+
+}

kernel/kernel/Memory/MemoryRegion.cpp

@@ -0,0 +1,50 @@
+#include <kernel/Memory/MemoryRegion.h>
+
+namespace Kernel
+{
+
+	MemoryRegion::MemoryRegion(PageTable& page_table, size_t size, Type type, PageTable::flags_t flags)
+		: m_page_table(page_table)
+		, m_size(size)
+		, m_type(type)
+		, m_flags(flags)
+	{
+	}
+	
+	MemoryRegion::~MemoryRegion()
+	{
+		if (m_vaddr)
+			m_page_table.unmap_range(m_vaddr, m_size);
+	}
+
+	BAN::ErrorOr<void> MemoryRegion::initialize(AddressRange address_range)
+	{
+		size_t needed_pages = BAN::Math::div_round_up<size_t>(m_size, PAGE_SIZE);
+		m_vaddr = m_page_table.reserve_free_contiguous_pages(needed_pages, address_range.start);
+		if (m_vaddr == 0)
+			return BAN::Error::from_errno(ENOMEM);
+		if (m_vaddr + needed_pages * PAGE_SIZE > address_range.end)
+			return BAN::Error::from_errno(ENOMEM);
+		return {};
+	}
+
+	bool MemoryRegion::contains(vaddr_t address) const
+	{
+		return m_vaddr <= address && address < m_vaddr + m_size;
+	}
+
+	bool MemoryRegion::contains_fully(vaddr_t address, size_t size) const
+	{
+		return m_vaddr <= address && address + size < m_vaddr + m_size;
+	}
+
+	bool MemoryRegion::overlaps(vaddr_t address, size_t size) const
+	{
+		if (address + size < m_vaddr)
+			return false;
+		if (address >= m_vaddr + m_size)
+			return false;
+		return true;
+	}
+
+}

kernel/kernel/Process.cpp

@@ -7,6 +7,7 @@
 #include <kernel/InterruptController.h>
 #include <kernel/LockGuard.h>
 #include <kernel/Memory/Heap.h>
+#include <kernel/Memory/MemoryBackedRegion.h>
 #include <kernel/Memory/PageTableScope.h>
 #include <kernel/Process.h>
 #include <kernel/Scheduler.h>
@@ -128,23 +129,23 @@ namespace Kernel
 			if (auto rem = needed_bytes % PAGE_SIZE)
 				needed_bytes += PAGE_SIZE - rem;
 
-			auto argv_range = MUST(VirtualRange::create_to_vaddr_range(
+			auto argv_region = MUST(MemoryBackedRegion::create(
 				process->page_table(),
-				0x400000, KERNEL_OFFSET,
 				needed_bytes,
-				PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present,
+				{ .start = 0x400000, .end = KERNEL_OFFSET },
-				true
+				MemoryRegion::Type::PRIVATE,
+				PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present
 			));
 
-			uintptr_t temp = argv_range->vaddr() + sizeof(char*) * 2;
+			uintptr_t temp = argv_region->vaddr() + sizeof(char*) * 2;
-			argv_range->copy_from(0, (uint8_t*)&temp, sizeof(char*));			
+			MUST(argv_region->copy_data_to_region(0, (const uint8_t*)&temp, sizeof(char*)));
 
 			temp = 0;
-			argv_range->copy_from(sizeof(char*), (uint8_t*)&temp, sizeof(char*));	
+			MUST(argv_region->copy_data_to_region(sizeof(char*), (const uint8_t*)&temp, sizeof(char*)));
 
-			argv_range->copy_from(sizeof(char*) * 2, (const uint8_t*)path.data(), path.size());
+			MUST(argv_region->copy_data_to_region(sizeof(char*) * 2, (const uint8_t*)path.data(), path.size()));
 
-			MUST(process->m_mapped_ranges.push_back(BAN::move(argv_range)));
+			MUST(process->m_mapped_regions.push_back(BAN::move(argv_region)));
 		}
 
 		process->m_userspace_info.argc = 1;
@@ -172,7 +173,8 @@ namespace Kernel
 	Process::~Process()
 	{
 		ASSERT(m_threads.empty());
-		ASSERT(m_mapped_ranges.empty());
+		ASSERT(m_mapped_regions.empty());
+		ASSERT(!m_loadable_elf);
 		ASSERT(m_exit_status.waiting == 0);
 		ASSERT(&PageTable::current() != m_page_table.ptr());
 	}
@@ -205,7 +207,8 @@ namespace Kernel
 		m_open_file_descriptors.close_all();
 
 		// NOTE: We must unmap ranges while the page table is still alive
-		m_mapped_ranges.clear();
+		m_mapped_regions.clear();
+		m_loadable_elf.clear();
 	}
 
 	void Process::on_thread_exit(Thread& thread)
@@ -318,10 +321,10 @@ namespace Kernel
 		OpenFileDescriptorSet open_file_descriptors(m_credentials);
 		TRY(open_file_descriptors.clone_from(m_open_file_descriptors));
 
-		BAN::Vector<BAN::UniqPtr<VirtualRange>> mapped_ranges;
+		BAN::Vector<BAN::UniqPtr<MemoryRegion>> mapped_regions;
-		TRY(mapped_ranges.reserve(m_mapped_ranges.size()));
+		TRY(mapped_regions.reserve(m_mapped_regions.size()));
-		for (auto& mapped_range : m_mapped_ranges)
+		for (auto& mapped_region : m_mapped_regions)
-			MUST(mapped_ranges.push_back(TRY(mapped_range->clone(*page_table))));
+			MUST(mapped_regions.push_back(TRY(mapped_region->clone(*page_table))));
 
 		auto loadable_elf = TRY(m_loadable_elf->clone(*page_table));
 
@@ -330,7 +333,7 @@ namespace Kernel
 		forked->m_working_directory = BAN::move(working_directory);
 		forked->m_page_table = BAN::move(page_table);
 		forked->m_open_file_descriptors = BAN::move(open_file_descriptors);
-		forked->m_mapped_ranges = BAN::move(mapped_ranges);
+		forked->m_mapped_regions = BAN::move(mapped_regions);
 		forked->m_loadable_elf = BAN::move(loadable_elf);
 		forked->m_is_userspace = m_is_userspace;
 		forked->m_userspace_info = m_userspace_info;
@@ -373,7 +376,7 @@ namespace Kernel
 
 			m_open_file_descriptors.close_cloexec();
 
-			m_mapped_ranges.clear();
+			m_mapped_regions.clear();
 			m_loadable_elf.clear();
 
 			m_loadable_elf = TRY(load_elf_for_exec(m_credentials, executable_path, m_working_directory, page_table()));
@@ -387,8 +390,8 @@ namespace Kernel
 			ASSERT(&Process::current() == this);
 
 			// allocate memory on the new process for arguments and environment
-			auto create_range =
+			auto create_region =
-				[&](const auto& container) -> BAN::UniqPtr<VirtualRange>
+				[&](BAN::Span<BAN::String> container) -> BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>>
 				{
 					size_t bytes = sizeof(char*);
 					for (auto& elem : container)
@@ -397,36 +400,36 @@ namespace Kernel
 					if (auto rem = bytes % PAGE_SIZE)
 						bytes += PAGE_SIZE - rem;
 
-					auto range = MUST(VirtualRange::create_to_vaddr_range(
+					auto region = TRY(MemoryBackedRegion::create(
 						page_table(),
-						0x400000, KERNEL_OFFSET,
 						bytes,
-						PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present,
+						{ .start = 0x400000, .end = KERNEL_OFFSET },
-						true
+						MemoryRegion::Type::PRIVATE,
+						PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present
 					));
 
 					size_t data_offset = sizeof(char*) * (container.size() + 1);
 					for (size_t i = 0; i < container.size(); i++)
 					{
-						uintptr_t ptr_addr = range->vaddr() + data_offset;
+						uintptr_t ptr_addr = region->vaddr() + data_offset;
-						range->copy_from(sizeof(char*) * i, (const uint8_t*)&ptr_addr, sizeof(char*));
+						TRY(region->copy_data_to_region(sizeof(char*) * i, (const uint8_t*)&ptr_addr, sizeof(char*)));
-						range->copy_from(data_offset, (const uint8_t*)container[i].data(), container[i].size());
+						TRY(region->copy_data_to_region(data_offset, (const uint8_t*)container[i].data(), container[i].size()));
 						data_offset += container[i].size() + 1;
 					}
 
 					uintptr_t null = 0;
-					range->copy_from(sizeof(char*) * container.size(), (const uint8_t*)&null, sizeof(char*));
+					TRY(region->copy_data_to_region(sizeof(char*) * container.size(), (const uint8_t*)&null, sizeof(char*)));
 
-					return BAN::move(range);
+					return BAN::UniqPtr<MemoryRegion>(BAN::move(region));
 				};
 
-			auto argv_range = create_range(str_argv);
+			auto argv_region = MUST(create_region(str_argv.span()));
-			m_userspace_info.argv = (char**)argv_range->vaddr();
+			m_userspace_info.argv = (char**)argv_region->vaddr();
-			MUST(m_mapped_ranges.push_back(BAN::move(argv_range)));
+			MUST(m_mapped_regions.push_back(BAN::move(argv_region)));
 
-			auto envp_range = create_range(str_envp);
+			auto envp_region = MUST(create_region(str_envp.span()));
-			m_userspace_info.envp = (char**)envp_range->vaddr();
+			m_userspace_info.envp = (char**)envp_region->vaddr();
-			MUST(m_mapped_ranges.push_back(BAN::move(envp_range)));
+			MUST(m_mapped_regions.push_back(BAN::move(envp_region)));
 
 			m_userspace_info.argc = str_argv.size();
 
@@ -544,11 +547,11 @@ namespace Kernel
 			return true;
 		}
 
-		for (auto& mapped_range : m_mapped_ranges)
+		for (auto& region : m_mapped_regions)
 		{
-			if (!mapped_range->contains(address))
+			if (!region->contains(address))
 				continue;
-			TRY(mapped_range->allocate_page_for_demand_paging(address));
+			TRY(region->allocate_page_containing(address));
 			return true;
 		}
 
@@ -824,17 +827,17 @@ namespace Kernel
 			if (args->len % PAGE_SIZE != 0)
 				return BAN::Error::from_errno(EINVAL);
 
-			auto range = TRY(VirtualRange::create_to_vaddr_range(
+			auto region = TRY(MemoryBackedRegion::create(
 				page_table(),
-				0x400000, KERNEL_OFFSET,
 				args->len,
-				PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present,
+				{ .start = 0x400000, .end = KERNEL_OFFSET },
-				false
+				MemoryRegion::Type::PRIVATE,
+				PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present
 			));
 
 			LockGuard _(m_lock);
-			TRY(m_mapped_ranges.push_back(BAN::move(range)));
+			TRY(m_mapped_regions.push_back(BAN::move(region)));
-			return m_mapped_ranges.back()->vaddr();
+			return m_mapped_regions.back()->vaddr();
 		}
 
 		return BAN::Error::from_errno(ENOTSUP);
@@ -851,13 +854,10 @@ namespace Kernel
 
 		LockGuard _(m_lock);
 
-		for (size_t i = 0; i < m_mapped_ranges.size(); i++)
+		// FIXME: We should only map partial regions
-		{
+		for (size_t i = 0; i < m_mapped_regions.size(); i++)
-			auto& range = m_mapped_ranges[i];
+			if (m_mapped_regions[i]->overlaps(vaddr, len))
-			if (vaddr + len < range->vaddr() || vaddr >= range->vaddr() + range->size())
+				m_mapped_regions.remove(i);
-				continue;
-			m_mapped_ranges.remove(i);
-		}
 
 		return 0;
 	}
@@ -1341,10 +1341,11 @@ namespace Kernel
 			return;
 
 		// FIXME: should we allow cross mapping access?
-		for (auto& mapped_range : m_mapped_ranges)
+		for (auto& mapped_region : m_mapped_regions)
-			if (vaddr >= mapped_range->vaddr() && vaddr + size <= mapped_range->vaddr() + mapped_range->size())
+			mapped_region->contains_fully(vaddr, size);
 				return;
 
+		// FIXME: elf should contain full range [vaddr, vaddr + size)
 		if (m_loadable_elf->contains(vaddr))
 			return;