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Re: exercising current aarch64 kprobe support with systemtap
- From: William Cohen <wcohen at redhat dot com>
- To: David Long <dave dot long at linaro dot org>, systemtap at sourceware dot org, Pratyush Anand <panand at redhat dot com>, Mark Brown <broonie at linaro dot org>
- Cc: Jeremy Linton <jlinton at redhat dot com>, David Smith <dsmith at redhat dot com>
- Date: Thu, 23 Jun 2016 09:42:19 -0400
- Subject: Re: exercising current aarch64 kprobe support with systemtap
- Authentication-results: sourceware.org; auth=none
- References: <befacf57-b8eb-2926-8f4f-742f0f055a4c at redhat dot com> <d03cd7b7-3d6a-4e4d-71b6-a7325ddd76f3 at redhat dot com> <8f40d0b9-5550-92f9-d1c5-8769f52304c0 at redhat dot com> <576B5501 dot 1030106 at linaro dot org>
On 06/22/2016 11:18 PM, David Long wrote:
> 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
>
Hi Dave,
I have pulled the v14 branch and have it built, and gave it a try.
When running the tests on various kernels I typically see message about the hrtimer interrupt like the following during the run:
...
Running /root/systemtap_write/systemtap/testsuite/systemtap.onthefly/kprobes_onthefly.exp ...
[ 197.217699] stap_ab30d3b6ca1d8e512f40980479fd57e_18018: module verification failed: signature and/or required key missing - tainting kernel
[ 534.166223] Scheduler tracepoints stat_sleep, stat_iowait, stat_blocked and stat_runtime require the kernel parameter schedstats=enabled or kernel.sched_schedstats=1
[ 534.205668] hrtimer: interrupt took 241848 ns
...
Hmmm, it successfully completed the run with the v14 branch four times.
# make installcheck RUNTESTFLAGS="--debug systemtap.onthefly/kprobes_onthefly.exp"
...
tail systemtap.sum
PASS: kprobes_onthefly - otf_stress_1ms_iter_50 (survived)
PASS: kprobes_onthefly - otf_stress_500us_iter_50 (survived)
PASS: kprobes_onthefly - otf_stress_100us_iter_50 (survived)
PASS: kprobes_onthefly - otf_stress_prof_iter_2000 (survived)
PASS: kprobes_onthefly - otf_stress_hard_iter_2000 (survived)
PASS: kprobes_onthefly - otf_stress_max_iter_5000 (survived)
=== systemtap Summary ===
# of expected passes 22
What were the bug fixes and changes in v14? Alternatively could there be something else in the kernel I was using previously (e.g. the uprobes patches).
-Will