Re: [PATCH v3 0/5] ARM64: Add kernel probes(Kprobes) support

[Steve Capper <steve.capper@linaro.org>]

On 4 December 2014 at 02:48, David Long <dave.long@linaro.org> wrote:
> On 12/03/14 20:16, William Cohen wrote:
>
> [...]
>
>>
>> The perf issue seems to be independent and can be reproduced without using
>> any kprobe support.  I need to get a simple reproducer and mention it on the
>> linux-perf-user list.
>>
>> -Will
>>
>
>
> OK, my confusion came from all the different things perf can use.  I have
> not yet been able to reproduce the "perf stat" failure, but I do see the
> failure with Steve's example using tracepoints.  I had thought that was
> using kprobes, but apparently it just uses tracepoints.  These look like two
> different failures to me:  One related to tracepoints, and one in the PMU
> driver.
>
> Since this seems unrelated to kprobes I don't plan on pursuing these
> particular problems.
>
> -dl
>

Sorry for the late reply...

The example I had was:
echo "p:memcpy memcpy %x2" > /sys/kernel/debug/tracing/kprobe_events
perf record -e kprobes:memcpy -a sleep 5

[then crash due to IRQs being unexpectedly disabled in the ext4 code]

Isn't that a kprobe problem?

Cheers,
--
Steve