关于操作系统TSS的问题

unuse1ess

最近在做操作系统，已经实现了r0到r3的跳转，但是在中断的时候cpu又触发了无效TSS的异常，然后系统直接挂掉重启，有那个大佬帮忙看看是哪里出了问题
TASK_STATE_SEGMENT tss;

void init_tss()
{
        /* Initialize TSS and TR */
        memset_w((word*)&tss, 0, sizeof(TASK_STATE_SEGMENT) >> 1);

        tss.ss0 = KERNEL_DS;
        tss.io_bitmap_base = sizeof(tss);                /* No IO bitmap */

        load_tr(add_tss_descriptor((dword)&tss, sizeof(TASK_STATE_SEGMENT)));
}
word add_tss_descriptor(dword seg_base, dword seg_limit)
{
        return add_global_descriptor(seg_base, seg_limit,
                SEG_PRESENT | DPL_RING0 | SYSTEM_DESCPRITOR | AVAILABLE_386TSS, USE_32BITS_OPERAND);
}
word add_global_descriptor(dword seg_base, dword seg_limit, byte authority, byte attr)
{
        if (avl_gdt_index > NUM_OF_GDT_DESC)
                return 0;

        seg_limit--;

        gdt[avl_gdt_index].seg_limit_low = LOWORD(seg_limit);
        gdt[avl_gdt_index].seg_limit_high = HIWORD(seg_limit) & 0xf;

        gdt[avl_gdt_index].seg_base_low = LOWORD(seg_base);
        gdt[avl_gdt_index].seg_base_mid = LOBYTE(HIWORD(seg_base));
        gdt[avl_gdt_index].seg_base_high = HIBYTE(HIWORD(seg_base));

        gdt[avl_gdt_index].access_authority = authority;
        gdt[avl_gdt_index].attribute = attr;

        /* Next available index */
        avl_gdt_index++;

        return (avl_gdt_index - 1) << 3;
}

_load_tr:
        push ebp
        mov ebp, esp

        ltr [ebp + 8]

        leave
        ret

unuse1ess

找到问题了，原来是KERNEL_DS的值设置错误导致CPU在切换特权级的检查里发现SS的值是无效的，直接无效TSS异常