x86/traps: Stop using ist_enter/exit() in do_int3()

mainline inclusion
from mainline-v5.7-rc1
commit 65c668f5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V


CVE: NA

--------------------------------

harder to change ist_enter() and ist_exit()'s behavior.  Instead open-code
the very small amount of required logic.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200225220217.150607679@linutronix.de


Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>