init_user_proc.c

static inline Axel_state_code init_user_process(void) {
    // プロセス構造体を新規確保
    Process* p = alloc_proc(NULL);
    User_segments* us = &p->u_segs;

    // プログラム用のメモリ確保
    us->text.addr  = DEFAULT_TEXT_ADDR;
    us->text.size  = 0;
    us->stack.addr = DEFAULT_STACK_TOP_ADDR;
    us->stack.size = 0;
    expand_segment(p, &us->text, DEFAULT_TEXT_SIZE);
    expand_segment(p, &us->stack, DEFAULT_STACK_SIZE);

    // 実行を再開アドレスをinterrupt_returnに設定
    p->thread.ip   = (uintptr_t)interrupt_return;
    
    // カーネルモードスタックを操作し、割り込まれた時のように設定
    p->thread.sp   = p->km_stack;
    p->thread.sp -= sizeof(Interrupt_frame);
    Interrupt_frame* intf = (Interrupt_frame*)p->thread.sp;
    p->thread.iframe = intf;
    memset(intf, 0, sizeof(Interrupt_frame));

    intf->ds       = USER_DATA_SEGMENT_SELECTOR;
    intf->es       = USER_DATA_SEGMENT_SELECTOR;
    intf->fs       = USER_DATA_SEGMENT_SELECTOR;
    intf->gs       = USER_DATA_SEGMENT_SELECTOR;
    intf->eip      = ECAST_UINT32(us->text.addr);
    intf->cs       = USER_CODE_SEGMENT_SELECTOR;
    intf->eflags   = 0x00000200;
    intf->prev_esp = ECAST_UINT32(us->stack.addr + DEFAULT_STACK_SIZE);
    intf->prev_ss  = USER_DATA_SEGMENT_SELECTOR;

    /* 実行プログラムをディスクから読み込み */
    File* f = resolve_path(axel_s.fs, "init");
    void* fbuf = kmalloc(f->size);
    if (f->belong_fs->access_file(FILE_READ, f, fbuf) != AXEL_SUCCESS ) {
        kfree(fbuf);
        return AXEL_FAILED;
    }

    set_cpu_pdt(get_page_phys_addr(&p->pdt_page));
    memcpy((void*)us->text.addr, fbuf, f->size);
    set_cpu_pdt(vir_to_phys_addr((uintptr_t)(get_kernel_pdt())));
    kfree(fbuf);

    // プロセスの設定が終わったので実行可能状態へ
    p->state = PROC_STATE_RUN;

    return AXEL_SUCCESS;
}