Method exit

lab8/src/5/src/kernel/program.cpp:514–565

void ProgramManager::exit(int ret)
{
    // 关中断
    interruptManager.disableInterrupt();
    
    // 第一步，标记PCB状态为`DEAD`并放入返回值。
    PCB *program = this->running;
    program->retValue = ret;
    program->status = ProgramStatus::DEAD;

    int *pageDir, *page;
    int paddr;

    // 第二步，如果PCB标识的是进程，则释放进程所占用的物理页、页表、页目录表和虚拟地址池bitmap的空间。
    if (program->pageDirectoryAddress)
    {
        pageDir = (int *)program->pageDirectoryAddress;
        for (int i = 0; i < 768; ++i)
        {
            if (!(pageDir[i] & 0x1))
            {
                continue;
            }

            page = (int *)(0xffc00000 + (i << 12));

            for (int j = 0; j < 1024; ++j)
            {
                if(!(page[j] & 0x1)) {
                    continue;
                }

                paddr = memoryManager.vaddr2paddr((i << 22) + (j << 12));
                memoryManager.releasePhysicalPages(AddressPoolType::USER, paddr, 1);
            }

            paddr = memoryManager.vaddr2paddr((int)page);
            memoryManager.releasePhysicalPages(AddressPoolType::USER, paddr, 1);
        }

        memoryManager.releasePages(AddressPoolType::KERNEL, (int)pageDir, 1);
        
        int bitmapBytes = ceil(program->userVirtual.resources.length, 8);
        int bitmapPages = ceil(bitmapBytes, PAGE_SIZE);

        memoryManager.releasePages(AddressPoolType::KERNEL, (int)program->userVirtual.resources.bitmap, bitmapPages);

    }

    // 第三步，立即执行线程/进程调度。
    schedule();
}