livepatch/arm64: Fix current backtracking in klp_check_calltrace

hulk inclusion
category: bugfix
bugzilla: 51921
CVE: NA

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We through stack checking to ensure the consistency of livepatch.
Task blocked in __switch_to when switch out, thread_saved_fs/pc
store the FP and PC when switching, it can be useful when tracing
blocked threads. For running task, __builtin_frame_address can be
used, but it's difficult to backtracking the running task on other
CPUs.

Fortunately, all CPUs will stay in this function, the current's
backtrace is so similar. so just backtracking the current on this
CPU, skip the current of other CPUs.

Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Reviewed-by: Li Bin <huawei.libin@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Dong Kai <dongkai11@huawei.com>

Signed-off-by: Ye Weihua <yeweihua4@huawei.com>
Reviewed-by: Yang Jihong <yangjihong1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>