Method create_userspace

kernel/kernel/Thread.cpp:195–239

	}

	BAN::ErrorOr<Thread*> Thread::create_userspace(Process* process, PageTable& page_table, vaddr_t userspace_stack_vaddr, size_t userspace_stack_size, vaddr_t entry_point, vaddr_t stack_pointer)
	{
		ASSERT(process);

		// Create the thread object
		Thread* thread = new Thread(s_next_tid++, process);
		if (thread == nullptr)
			return BAN::Error::from_errno(ENOMEM);
		BAN::ScopeGuard thread_deleter([thread] { delete thread; });

		thread->m_is_userspace = true;

		thread->m_kernel_stack = TRY(VirtualRange::create_to_vaddr_range(
			page_table,
			{ userspace_stack_base, USERSPACE_END },
			kernel_stack_size,
			PageTable::Flags::ReadWrite | PageTable::Flags::Present,
			true
		));

		thread->m_userspace_stack_vaddr = userspace_stack_vaddr;
		thread->m_userspace_stack_size  = userspace_stack_size;

		// Initialize stack for returning
		PageTable::with_fast_page(thread->kernel_stack().paddr_of(thread->kernel_stack_top() - PAGE_SIZE), [=] {
			uintptr_t cur_sp = PageTable::fast_page() + PAGE_SIZE;
			write_to_stack(cur_sp, 0x20 | 3);
			write_to_stack(cur_sp, stack_pointer);
			write_to_stack(cur_sp, 0x202);
#if ARCH(x86_64)
			write_to_stack(cur_sp, 0x28 | 3);
#elif ARCH(i686)
			write_to_stack(cur_sp, 0x18 | 3);
#endif
			write_to_stack(cur_sp, entry_point);
		});

		thread->m_yield_registers = {};
		thread->m_yield_registers.ip = reinterpret_cast<vaddr_t>(start_userspace_thread);
		thread->m_yield_registers.sp = thread->kernel_stack_top() - 5 * sizeof(uintptr_t);

		thread_deleter.disable();

		return thread;
	}

	Thread::Thread(pid_t tid, Process* process)
		: m_tid(tid), m_process(process)