smp启动-smp_init

上一篇：smp_prepare_cpus

https://www.cnblogs.com/zhangzhiwei122/p/16093412.html
 

参考-总流程：https://www.cnblogs.com/pengdonglin137/p/11925299.html

 参考：https://zhuanlan.zhihu.com/p/373964690

 

start_kernel -> rest_init-> kernel_thread(kernel_init) & kernel_init-> kernel_init_freeable->smp_init

start_kernel -> rest_init-> kernel_thread 函数创建新 task， 新task 执行 kernel_init 函数

kernel_init 调用 kernel_init_freeable

1497 - 等待 kthreadd_done , 这个在 rest_init 函数里面  713        complete(&kthreadd_done);

1518 - 调用 smp_init

1492static noinline void __init kernel_init_freeable(void)
1493{
1494        /*
1495         * Wait until kthreadd is all set-up.
1496         */
1497        wait_for_completion(&kthreadd_done);

1507        cad_pid = task_pid(current);
1508
1509        smp_prepare_cpus(setup_max_cpus);
1510
1511        workqueue_init();
1512
1513        init_mm_internals();
1514
1515        do_pre_smp_initcalls();
1517
1518        smp_init();

 

smp_init

start_kernel
->arch_call_rest_init
 ->rest_init
  ->kernel_init,
   ->kernel_init_freeable
    ->smp_prepare_cpus  //arch/arm64/kernel/smp.c
     ->smp_init  //kernel/smp.c  (这是从处理器启动的函数)
      ->cpu_up
       ->do_cpu_up
        ->_cpu_up
         ->cpuhp_up_callbacks
          ->cpuhp_invoke_callback
          ->cpuhp_hp_states[CPUHP_BRINGUP_CPU]
           ->bringup_cpu
            ->__cpu_up  //arch/arm64/kernel/smp.c
             ->boot_secondary
              ->cpu_ops[cpu]->cpu_boot(cpu)
               ->cpu_psci_ops.cpu_boot
                ->cpu_psci_cpu_boot   //arch/arm64/kernel/psci.c
                 46 static int cpu_psci_cpu_boot(unsigned int cpu)
                   47 { 
                   48         int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(secondary_entry));
                   49         if (err)
                   50                 pr_err("failed to boot CPU%d (%d)\n", cpu, err);
                   51   
                   52         return err;
                   53 } 

psci_ops.cpu_on

在 drivers/firmware/psci/psci.c 中赋值，为psci_cpu_on

 186static int psci_cpu_on(unsigned long cpuid, unsigned long entry_point)
 187{
 188        int err;
 189        u32 fn;
 190
 191        fn = psci_function_id[PSCI_FN_CPU_ON];
 192        err = invoke_psci_fn(fn, cpuid, entry_point, 0);
 193        return psci_to_linux_errno(err);
 194}

psci-执行 SMC 指令，cpu 陷入到 el3 中，执行el3 中断代码，完成开核动作

然后

1、新的核心执行    __pa_symbol(secondary_entry)

2、发出SMC 中断调用的核心，返回 ，到 psci_cpu_on 函数的 192 行，继续执行下面的 193 行

   ->psci_cpu_on()
     ->invoke_psci_fn()
      ->__invoke_psci_fn_smc()
        -> arm_smccc_smc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res)  //这个时候x0=function_id  x1=arg0, x2=arg1, x3arg2,...
         ->arm_smccc_smc // include/linux/arm-smccc.h
          ->__arm_smccc_smc()  // arch/arm64/kernel/smccc-call.S
           ->SMCCC   smc //arch/arm64/kernel/smccc-call.S
             ->    20         .macro SMCCC instr
                21         .cfi_startproc
                22         \instr  #0   //即是ｓｍｃ #0  陷入到ｅｌ3
                23         ldr     x4, [sp]
                24         stp     x0, x1, [x4, #ARM_SMCCC_RES_X0_OFFS]
                25         stp     x2, x3, [x4, #ARM_SMCCC_RES_X2_OFFS]
                26         ldr     x4, [sp, #8]
                27         cbz     x4, 1f /* no quirk structure */
                28         ldr     x9, [x4, #ARM_SMCCC_QUIRK_ID_OFFS]
                29         cmp     x9, #ARM_SMCCC_QUIRK_QCOM_A6
                30         b.ne    1f
                31         str     x6, [x4, ARM_SMCCC_QUIRK_STATE_OFFS]
                32 1:      ret
                33         .cfi_endproc
                34         .endm

 

下一篇： smp_init - idle threads init  hotplug threads init

https://www.cnblogs.com/zhangzhiwei122/p/16095130.html