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

[Poonam Bajaj]

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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