异常中断等级

SVC系统调用等指令，会涉及到：

• 跳转到异常中断 = 触发异常中断

对应的：异常（中断）等级=Exception Level，也有不同分类：

• 图
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  • 其中：EL0和EL1之间的交互转换方式
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• 文字
  • SVC - Supervisor call
    • Causes an exception targeting EL1.
    • Used by an application to call the OS.
  • HVC - Hypervisor call
    • Causes an exception targeting EL2.
    • Used by an OS to call the hypervisor, not available at EL0.
  • SMC - Secure monitor call
    • Causes an exception targeting EL3.
    • Used by an OS or hypervisor to call the EL3 firmware, not available at EL0.