所有崩溃都有cpu执行指令引起。主要包含两种：1）指令非法；2）访问非法。
访问非法又包含两种：（1）访问不存在；2）访问越界；3（）访问受限。
指令非法：cpu不支持的指令。
An illegal opcode, also called an undocumented instruction, is an instruction to a CPU that is not mentioned in any official documentation released by the CPU's designer or manufacturer, which nevertheless has an effect.
https://en.wikipedia.org/wiki/Illegal_opcode
指令属于线程；线程有自己的合法资源；线程运行在一个沙盒中，撞破了沙盒的界限，就会被系统kill掉。