274     uint64_t new_brk = PAGE_2M_ALIGN(regs->r8);  in sys_brk()  local
289     if (new_brk > current_pcb->addr_limit) // 堆地址空间超过限制  in sys_brk()
293     if (new_brk >= current_pcb->mm->brk_end)  in sys_brk()
294         offset = (int64_t)(new_brk - current_pcb->mm->brk_end);  in sys_brk()
296         offset = -(int64_t)(current_pcb->mm->brk_end - new_brk);  in sys_brk()
298     new_brk = mm_do_brk(current_pcb->mm->brk_end, offset); // 扩展堆内存空间  in sys_brk()
300     current_pcb->mm->brk_end = new_brk;  in sys_brk()
316         uint64_t new_brk = PAGE_2M_ALIGN(retval + regs->r8);  in sys_sbrk()  local
317         if (new_brk > current_pcb->addr_limit) // 堆地址空间超过限制  in sys_sbrk()
319             kdebug("exceed mem limit, new_brk = %#018lx", new_brk);  in sys_sbrk()
329     uint64_t new_brk = mm_do_brk(current_pcb->mm->brk_end, (int64_t)regs->r8); // 调整堆内存空间  in sys_sbrk()  local
331     current_pcb->mm->brk_end = new_brk;  in sys_sbrk()