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

[David Holmes]

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
>>>