Method RecursiveClonePageTable

src/memory/virtual_memory.cpp:244–296

}

auto VirtualMemory::RecursiveClonePageTable(uint64_t* src_table,
                                            uint64_t* dst_table, size_t level,
                                            bool copy_mappings)
    -> Expected<void> {
  assert(src_table != nullptr && "RecursiveClonePageTable: src_table is null");
  assert(dst_table != nullptr && "RecursiveClonePageTable: dst_table is null");

  for (size_t i = 0; i < kEntriesPerTable; ++i) {
    uint64_t src_pte = src_table[i];
    if (!cpu_io::virtual_memory::IsPageTableEntryValid(src_pte)) {
      continue;
    }

    if (level > 0) {
      // 非最后一级，需要递归复制子页表
      auto src_pa = cpu_io::virtual_memory::PageTableEntryToPhysical(src_pte);
      auto* src_next_table = reinterpret_cast<uint64_t*>(src_pa);

      // 分配新的子页表
      auto* dst_next_table = aligned_alloc(cpu_io::virtual_memory::kPageSize,
                                           cpu_io::virtual_memory::kPageSize);
      if (dst_next_table == nullptr) {
        return std::unexpected(Error(ErrorCode::kVmAllocationFailed));
      }

      // 清零新页表
      std::memset(dst_next_table, 0, cpu_io::virtual_memory::kPageSize);

      // 递归复制子页表
      auto result = RecursiveClonePageTable(
          src_next_table, reinterpret_cast<uint64_t*>(dst_next_table),
          level - 1, copy_mappings);
      if (!result.has_value()) {
        aligned_free(dst_next_table);
        return std::unexpected(result.error());
      }

      // 设置目标页表项指向新的子页表
      dst_table[i] = cpu_io::virtual_memory::PhysicalToPageTableEntry(
          reinterpret_cast<uint64_t>(dst_next_table),
          cpu_io::virtual_memory::GetTableEntryPermissions());
    } else {
      // 最后一级页表
      if (copy_mappings) {
        // 直接复制页表项（共享物理页）
        dst_table[i] = src_pte;
      }
      // 如果不复制映射，保持目标页表项为 0
    }
  }

  return {};
}

auto VirtualMemory::FindPageTableEntry(void* page_dir, void* virtual_addr,
                                       bool allocate) -> Expected<uint64_t*> {