[android-kernel] Nexus 6p deugging problem

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Hi, everyone. I am trying to debug the kernel on nexus 6p so I managed to
do that with this post.

https://blog.trendmicro.com/trendlabs-security-intelligence/practical-android-debugging-via-kgdb/

And I also succeeded in patch the single step problem with this post.

http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/290755.html

But here comes the problem, when set a breakpoint, I found that I can't hit
"continue". If I do that, I will get this error.

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8
[Switching to Thread 1104]

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8
[Switching to Thread 1425]

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8
[Switching to Thread 671]

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8
[Switching to Thread 965]

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8
[Switching to Thread 673]

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8
[Switching to Thread 965]

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8
[Switching to Thread 4769]

Breakpoint 1, __copy_from_user () at
arch/arm64/lib/copy_from_user.S:32
32 subs x2, x2, #8

Program received signal SIGTRAP, Trace/breakpoint trap.
[Switching to Thread 965]
__copy_from_user () at arch/arm64/lib/copy_from_user.S:33
33 b.mi 2f

So the problem comes when it moves on to next instruction. I don't know
why. Maybe it's because the multi-core or multi-thread. Can anyone help me?