virtual_memory.hpp

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#pragma once
 
#include <cpu_io.h>
#include <etl/singleton.h>
 
#include <cstddef>
#include <cstdint>
 
#include "expected.hpp"
 
class VirtualMemory {
 public:
  auto InitCurrentCore() const -> void;
 
  [[nodiscard]] auto MapMMIO(
      uint64_t phys_addr, size_t size,
      uint32_t flags = cpu_io::virtual_memory::GetKernelPagePermissions())
      -> Expected<void*>;
 
  [[nodiscard]] auto MapPage(void* page_dir, void* virtual_addr,
                             void* physical_addr, uint32_t flags)
      -> Expected<void>;
 
  [[nodiscard]] auto UnmapPage(void* page_dir, void* virtual_addr)
      -> Expected<void>;
 
  [[nodiscard]] auto GetMapping(void* page_dir, void* virtual_addr)
      -> Expected<void*>;
 
  auto DestroyPageDirectory(void* page_dir, bool free_pages = false) -> void;
 
  [[nodiscard]] auto ClonePageDirectory(void* src_page_dir,
                                        bool copy_mappings = true)
      -> Expected<void*>;
 
 
  VirtualMemory();
  VirtualMemory(const VirtualMemory&) = delete;
  VirtualMemory(VirtualMemory&&) = default;
  auto operator=(const VirtualMemory&) -> VirtualMemory& = delete;
  auto operator=(VirtualMemory&&) -> VirtualMemory& = default;
  ~VirtualMemory() = default;
 
 private:
  void* kernel_page_dir_{nullptr};
 
  static constexpr size_t kEntriesPerTable =
      cpu_io::virtual_memory::kPageSize / sizeof(void*);
 
  auto RecursiveFreePageTable(uint64_t* table, size_t level, bool free_pages)
      -> void;
  auto RecursiveClonePageTable(uint64_t* src_table, uint64_t* dst_table,
                               size_t level, bool copy_mappings)
      -> Expected<void>;
 
  [[nodiscard]] auto FindPageTableEntry(void* page_dir, void* virtual_addr,
                                        bool allocate = false)
      -> Expected<uint64_t*>;
};
 
using VirtualMemorySingleton = etl::singleton<VirtualMemory>;