exercising current aarch64 kprobe support with systemtap

[David Long]

On 06/22/2016 04:24 PM, William Cohen wrote:
> Hi all,
>
> When running the current systemtap checked out from the git repository
> and a locally built kernel with the kprobes64-v13 patches (the
> test_upstream_arm64_devel branch of
> https://github.com/pratyushanand/linux) on Fedora 23 machine one of
> the kprobes_onthefly.exp tests is causing the machine to get in a
> state that requires rebooting to fix.  This can be triggered by running a
> portion of the systemtap tests with:
>
>   make installcheck RUNTESTFLAGS="--debug systemtap.onthefly/kprobes_onthefly.exp"
>
> When it gets to the kprobes_onthefly - otf_stress_max_iter_5000 test the
> console starts spewing the following and needs to be rebooted:
>
> [23394.036860] Unexpected kernel single-step exception at EL1
> [23394.042434] Unexpected kernel single-step exception at EL1
> [23394.048008] Unexpected kernel single-step exception at EL1
> [23394.053541] Unexpected kernel single-step exception at EL1
> [23394.059053] Unexpected kernel single-step exception at EL1
> [23394.064545] Unexpected kernel single-step exception at EL1
>
> Sorry I don't have the start of the failure it scrolled off the screen very quickly.
>
> -Will
>
>

I'll take a look and see what I can figure out.

In the meantime I did just push a v14 branch.  I'm doubtful that it will 
address the above problem even though it contains a few bug fixes.

-dl