Re: [PATCH 01/52] perf tools: Fix jump label always changing during tracing

Adrian Hunter
2014-07-23T07:16:54Z

On 07/23/2014 09:58 AM, Peter Zijlstra wrote:
> On Wed, Jul 23, 2014 at 09:07:32AM +0300, Adrian Hunter wrote:
>> On 07/22/2014 05:11 PM, Peter Zijlstra wrote:
>>> On Tue, Jul 22, 2014 at 11:00:34AM -0300, Arnaldo Carvalho de Melo wrote:
>>>> Em Tue, Jul 22, 2014 at 04:17:10PM +0300, Adrian Hunter escreveu:
>>>>> Intel PT decoding walks the object code to reconstruct
>>>>> the trace. A jump label change during tracing causes
>>>>> decoding errors.
>>>
>>> You'd better fix that, jump_labels can change any time and they're all
>>> over the frigging place.
>>>
>>
>> Perhaps a general method is needed to be able to deal with kernel
>> self-modifying code.
>
> I know people are looking at doing the same to userspace, is that also a
> problem?

Yes, most significantly JIT-compiled code.