Request for review: 6310967: SA: jstack -m produce failures in output

[Staffan Larsen]

Poonam,

The fix looks good. 

It's not clear to me if there is a good regression test for this already - if not, I'd really like to see one along with the fix.

Thanks,
/Staffan

On 14 jun 2012, at 06:10, Poonam Bajaj wrote:

> Could I get one more review for this fix, please.
> 
> Thanks,
> Poonam
> 
> On 6/13/2012 7:57 AM, David Holmes wrote:
>> 
>> On 13/06/2012 12:25 PM, Poonam Bajaj wrote: 
>>> Hi David, 
>>> 
>>> On 6/13/2012 7:35 AM, David Holmes wrote: 
>>>> Hi Poonam, 
>>>> 
>>>> It seems to me that rather than passing the ThreadProxy through to 
>>>> f.sender the frame, which has to be a frame of some thread, should 
>>>> already know what that thread is and so be able to access it directly. 
>>>> 
>>>> In other words: shouldn't each CFrame maintain a reference to the 
>>>> thread it corresponds to? 
>>> 
>>> Yes, it would have made more sense to have a reference of ThreadProxy in 
>>> the Frame classes. But that requires restructuring of lot more code. All 
>>> the Debugger classes (e.g. 
>>> agent/src/share/classes/sun/jvm/hotspot/debugger/linux/LinuxCDebugger.java) 
>>> also need to be touched that have the topFrameForThread() where we 
>>> create the first frame for the thread. 
>> 
>> Oh I see. I was hoping it would actually lead to fewer code changes. It seems risky to pass in a thread reference when there is only ever one valid thread reference that can be passed - but no way to verify that you actually pass the correct one. 
>> 
>>> This fix was mainly for 6uxx and it didn't seem reasonable to me to 
>>> restructure and touch too many classes for this simple fix. 
>> 
>> Ok. 
>> 
>> David 
>> ----- 
>> 
>>> Thanks, 
>>> Poonam 
>>> 
>>>> 
>>>> David 
>>>> 
>>>> On 12/06/2012 11:05 PM, Poonam Bajaj wrote: 
>>>>> Hi, 
>>>>> 
>>>>> Please review this fix for bug 6310967 
>>>>> <http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6310967>. 
>>>>> 
>>>>> 6310967 <http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6310967>: 
>>>>> SA: jstack -m produce failures in output 
>>>>> 
>>>>> http://cr.openjdk.java.net/~poonam/6310967/webrev.00/ 
>>>>> 
>>>>> Problem: jstack -m fails with UnalignedAddressException.The problem is 
>>>>> that while finding the caller frame of a frame in sender() method, we 
>>>>> don't check the validity of the frame pointer (rbp / ebp). 
>>>>> 
>>>>> These changes add a simple check that the frame pointer(rbp) should be a 
>>>>> valid pointer on the stack by making sure that it is not less than the 
>>>>> stack 
>>>>> pointer(rsp). 
>>>>> 
>>>>> 
>>>>> Thanks, 
>>>>> Poonam
>>>>>  
>>>>> 

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