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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>, Pratyush Anand <panand at redhat dot com>
- Cc: systemtap at sourceware dot org, Mark Brown <broonie at linaro dot org>, Jeremy Linton <jlinton at redhat dot com>, David Smith <dsmith at redhat dot com>
- Date: Thu, 23 Jun 2016 15:22:44 -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> <e5f466f7-4a60-efb3-d104-375807d271b2 at redhat dot com> <576C29E1 dot 8060805 at linaro dot org>
On 06/23/2016 02:26 PM, David Long wrote:
> On 06/23/2016 11:49 AM, William Cohen wrote:
>> 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 and Pratyush,
>>
>> I tried the kprobes64-v13 kernel and it also seems to work, so it lookw like the problem might be in the the
>> test_upstream_arm64_devel branch of https://github.com/pratyushanand/linux .
>>
>> -Will
>>
>
> I'm going to interpret that as meaning you know of no problem in the kprobes v14 patch that would give me pause to email it upstream. Do you disagree?
>
> -dl
>
Hi Dave,
Yes, the problem only seems to be in that other kernel from https://github.com/pratyushanand/linux with the kprobe and uprobe patches, so the arm64 patches do not appear to be the problem. I don't know what is causing the problem maybe there is something going on with the porting of the patches to that kernel or the patches included in there (uprobes/kexec) in there.
-Will