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1、Linux内核剖析之进程切换郭海林2012.10.20AT&T汇编基础AT&T汇编与Intel汇编比较GCC内联汇编进程切换概述__schedule()prev=rq->curr;next=pick_next_task(rq);if(likely(prev!=next))context_switch(rq,prev,next);执行进程的切换：切换页全局目录以安装一个新的地址空间切换内核态堆栈和硬件上下文进程切换概述硬件上下文——共享的CPU寄存器进程切换时，硬件上下文保存在：task_struct的类型为thread_struct的thread字段大部分寄存器，如esp,eip
2、...内核态堆栈状态寄存器、通用寄存器，如eax，ebx...switch_to宏pushflpushl%%ebpmovl%%esp,%[prev_sp]movl%[next_sp],%%espmovl$1f,%[prev_ip]pushl%[next_ip]jmp__switch_to1:popl%%ebppopfl/*outputparameters*/:[prev_sp]"=m"(prev->thread.sp),[prev_ip]"=m"(prev->thread.ip),"=a"(last)/*inputparameters:*/:[next_sp]"m"(next->
3、thread.sp),[next_ip]"m"(next->thread.ip),[prev]"a"(prev),[next]"d"(next)switch_to(prev,next,last)切换过程ABt_st_s内核栈内核栈thread_infothread_infopushflpushl%%ebpmovl%%esp,%[prev_sp]movl%[next_sp],%%espmovl$1f,%[prev_ip]切换过程ABt_st_s内核栈内核栈thread_infothread_infopushflpushl%%ebpmovl%%esp,%[prev_sp]movl%[
4、next_sp],%%espmovl$1f,%[prev_ip]flags切换过程ABt_st_s内核栈内核栈thread_infothread_infopushflpushl%%ebpmovl%%esp,%[prev_sp]movl%[next_sp],%%espmovl$1f,%[prev_ip]flagsebp切换过程A(prev)B(next)t_st_s内核栈内核栈thread_infothread_infopushflpushl%%ebpmovl%%esp,%[prev_sp]movl%[next_sp],%%espmovl$1f,%[prev_ip]flagsebp
5、threadesp切换过程A(prev)B(next)t_st_s内核栈内核栈thread_infothread_infopushl%%ebpmovl%%esp,%[prev_sp]movl%[next_sp],%%espmovl$1f,%[prev_ip]pushl%[next_ip]flagsebpebpthreadspflagsthreadsp完成内核栈的切换！是不是就完成了进程的切换呢？切换过程A(prev)B(next)t_st_s内核栈内核栈thread_infothread_infomovl%[next_sp],%%espmovl$1f,%[prev_ip]push
6、l%[next_ip]jmp__switch_to1:flagsebpebpthreadspflagsthreadspip切换过程A(prev)B(next)t_st_s内核栈内核栈thread_infothread_infomovl%[next_sp],%%espmovl$1f,%[prev_ip]pushl%[next_ip]jmp__switch_to1:flagsebpebpthreadspflagsthreadspipmovl%[next_sp],%%espmovl$1f,%[prev_ip]pushl%[next_ip]jmp__switch_to1:eipip切换过
7、程A(prev)B(next)t_st_s内核栈内核栈thread_infothread_infomovl%[next_sp],%%espmovl$1f,%[prev_ip]pushl%[next_ip]jmp__switch_to1:flagsebpebpthreadspflagsthreadspippushl%[next_ip]jmp__switch_to1:popl%%ebppopfleip__switch_to是一个函数！ipreturn时，将jump之前压入栈中的元素e
