RFR (XS): 8046018: JVMTI Spec: can_redefine_any_class capability spec is inconsistent

[Daniel D. Daugherty]

On 5/21/19 2:19 AM, serguei.spitsyn at oracle.com wrote:
> Hi guys,
>
> I've found one more fragment in the IsModifiableClass spec which has 
> to be fixed.
>
>
> Updated webrev v2:
> http://cr.openjdk.java.net/~sspitsyn/webrevs/2019/8046018-jvmti-cap-spec.2/ 
>

src/hotspot/share/prims/jvmti.xml
     No comments.

Looks like there was a specific update to the spec to allow 
can_redefine_any_class
to include retransform (in addition to redefine):

1.1.82
13 February 2006     Doc fixes: update can_redefine_any_class to include 
retransform. Clarify that exception events cover all Throwables. In 
GetStackTrace, no test is done for start_depth too big if start_depth is 
zero, Clarify fields reported in Primitive Field Callback -- static vs 
instance. Repair confusing names of heap types, including callback 
names. Require consistent usage of stack depth in the face of thread 
launch methods. Note incompatibility of JVM TI memory management with 
other systems.

I can't tell if you've chased down that change and why you no longer
think that change is necessary.

I'm okay with the change, but I think you have more research to do here.

Dan


> Specdiff:
> http://cr.openjdk.java.net/~sspitsyn/webrevs/2019/8046018-jvmti-cap-spec.2/jvmti-specdiff/ 
>
>
>
> Enhancement:
>   https://bugs.openjdk.java.net/browse/JDK-8046018
>
> Related CSR:
>   https://bugs.openjdk.java.net/browse/JDK-8223915
>
>
> Thanks,
> Serguei
>
>
> On 5/20/19 21:43, serguei.spitsyn at oracle.com wrote:
>> Hi David,
>>
>> Thank you for looking at this!
>>
>>
>> On 5/20/19 20:53, David Holmes wrote:
>>> Hi Serguei,
>>>
>>> On 21/05/2019 4:07 am, serguei.spitsyn at oracle.com wrote:
>>>> Please, review a fix for enhancement:
>>>> https://bugs.openjdk.java.net/browse/JDK-8046018
>>>>
>>>> Related CSR:
>>>> https://bugs.openjdk.java.net/browse/JDK-8223915
>>>
>>> I have some comments on the CSR and about this change overall as to 
>>> me it is not a simple clarification at all, but potentially a 
>>> significant change in the meaning of the capability.
>>
>>
>> I've answered your question in the CSR with my comment.
>>
>>>> Webrev:
>>>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2019/8046018-jvmti-cap-spec.1/ 
>>>>
>>>
>>> You introduced a typo: modifialble
>>>
>>> Assuming this proceeds a similar change is needed earlier:
>>>
>>> 7444         <capability id="can_redefine_any_class">
>>> 7445           If possessed then all classes (except primitive, 
>>> array, and some implementation defined
>>> 7446           classes) are modifiable (redefine or retransform).
>>
>> Good catch, thanks!
>> I've updated the webrev in place.
>>
>> Thanks,
>> Serguei
>>
>>>
>>> Thanks,
>>> David
>>> -----
>>>
>>>>
>>>> Summary:
>>>>
>>>>    The fix is to make the JVMTI can_redefine_any_class capability 
>>>> spec more inconsistent.
>>>>    It is just about a couple of lines.
>>>>
>>>> Thanks,
>>>> Serguei
>>
>