Linux操作系统课程指导：Ch7-Interrupts-and-Interrupt-Handler

InterruptsandInterruptHandlersInterruptsandInterruptHandlersOSkernelismanagingthehardwareconnectedtothemachine,suchasharddisks,keyboards,miceandwirelessradios.CPUisfastanddeviceisalwaysslow,howtocommunicate?Polling:CPUchecksthehardwareperiodicallyInterrupt:hardwaresignalsthekernelDirectmemoryaccess(DMA):aspecialhardware2026/7/28LiangShi：LinuxOperatingSystems2OutlineInterruptsInterruptHandlersTopHalvesVs.BottomHalves(上半部和下半部)RegisteringanInterruptHandler（注册中断）WritinganInterruptHandler（编写中断）InterruptContext（中断上下文）ImplementingInterruptHandlers（实现中断）InterruptControl（中断控制）Conclusion2026/7/28LiangShi：LinuxOperatingSystems3InterruptsHardwarecangenerateinterruptsasynchronouslyatanytimeHardware->interruptcontroller->processor->kernel(handletheinterrupt)Interruptvalueassignedfordifferentinterrupt,alsocalledinterruptrequest(IRQ)lines.Hey,Ihavenewkeypresseswaiting!Readandprocessthesebadboys!Exceptions:occursynchronouslywithrespecttotheprocessorclock.(同步中断)2026/7/28LiangShi：LinuxOperatingSystems4Exceptionsoccursynchronouslywithrespecttotheprocessorclock.(同步中断)Twotypes:处理器探测异常由CPU执行指令时探测到一个反常条件时产生，如溢出、除0错等编程异常由编程者发出的特定请求产生，通常由int类指令触发通常叫做“软中断”例如系统调用对于处理器探测异常，根据异常时保存在内核堆栈中的eip的值可以进一步分为：故障(fault)：eip=引起故障的指令的地址通常可以纠正，处理完异常时，该指令被重新执行例如缺页异常陷阱(trap)：eip=随后要执行的指令的地址。异常中止(abort)：eip=？？？发生严重的错误。eip值无效，只有强制终止受影响的进程2026/7/28LiangShi：LinuxOperatingSystems52026/7/28LinuxOSAnalysis6/102故障非屏蔽中断陷阱，断点调试陷阱故障，缺页异常中止异常处理程序异常处理程序发出的信号InterruptHandlersThefunctionthekernelrunsinresponsetoaspecificinterruptiscalledaninterrupthandlerorinterruptserviceroutine(ISR).Theinterrupthandlerforadeviceispartofthedevicedriver–thekernelcodethatmanagesthedevice.Interrupthandleriscalledininterruptcontext(atomiccontext),differentfromprocesscontext,interruptcontextcannotbeblocked.Interrupthandlershouldrunasfastaspossible.

Hey,hardware,Ihearya;nowgetbacktowork!However,interrupthandlershavealargeamountofworktodo.2026/7/28LiangShi：LinuxOperatingSystems7TopHalvesVersusBottomHalvesInterrupthandlerneedstoexecutefastandperformalargeamountofworkInterrupthandlersarepartitionedintotwoparts:tophalvesandbottomhalves.Tophalfisrunimmediatelyuponreceiptoftheinterruptandperformsonlytheworkthatistime-criticalBottomhalfperformstheworkthatcanbedelayed.2026/7/28LiangShi：LinuxOperatingSystems8TimeCriticalFastandnotinterruptibleNoCriticalCanbedelayedandcanbeinterruptedBottomHalfTopHalfRegisteringanInterruptHandler2026/7/28LiangShi：LinuxOperatingSystems9flags2026/7/28LiangShi：LinuxOperatingSystems10name2026/7/28LiangShi：LinuxOperatingSystems11RegisteringanInterruptHandler2026/7/28LiangShi：LinuxOperatingSystems12Irqn:therequestedinterruptlineMy_interrupt:thehandlerFlags:IRQF_SHAREDName:my_deviceDev:my_devIrq:thefreedinterruptlineDev_id:fornotsharedline,removethehandleranddisabletheline,forsharedline,onlythedev_idhandlerisremoved.WritinganInterruptHandlerIrq:interruptlineDev_instance:deviceReturn:IRQ_NONEorIRQ_HANDLEDIRQF_SHAREDExample:real-timeclock2026/7/28LiangShi：LinuxOperatingSystems13WritinganInterruptHandler2026/7/28LiangShi：LinuxOperatingSystems14InterruptContextWhenexecutinganinterrupthandler,thekernelisininterruptcontextCompareprocesscontextandinterruptcontextProcesscontextonbehalfofaprocess,cansleepandinvoketheschedulerInterruptcontextdoesnotassociateprocess,cannotsleep,scheduleInterruptcontextistimecriticalbecausetheinterrupthandlerinterruptsothercode.Sharedstackwiththeinterruptedprocessorhastheirownstack,interruptstack.2026/7/28LiangShi：LinuxOperatingSystems15ImplementingInterruptHandlers2026/7/28LiangShi：LinuxOperatingSystems16ImplementingInterruptHandlers2026/7/28LiangShi：LinuxOperatingSystems17ImplementingInterruptHandlers2026/7/28LiangShi：LinuxOperatingSystems18/proc/interrupts2026/7/28LiangShi：LinuxOperatingSystems19InterruptlineTheinterruptcontrollerhandlingtheinterruptCountersofthenumberofinterruptsreceivednameInterruptControl2026/7/28LiangShi：LinuxOperatingSystems20InterruptControlTheobjectofthecontrolistoprovidesynchronizationLocal_irq_disable()(cli)Local_irq_enable()(sti)local_irq_save(flags)Local_irq_restore(flags)CanbecallbothinprocessandinterruptcontextNomoreglobalcli()–why?Disable_irq,disable_irq_nosync,enable_irq,synchronize_irq2026/7/28LiangShi：LinuxOperatingSystems21ConclusionWhatisinterrupt?CompareinterruptwithexceptionWhatisthecharacteristicsofinterrupt?Whatthetophalfandbottomhalf,why?Whatistheprocessfordesignani