RR 6313816: SA: jstack -m fails on Win32 : UnalignedAddressException

[Kevin Walls]

Hi -

I'd like to get another review from an openjdk user/reviewer/...

Thanks
Kevin


On 03/05/13 09:32, Kevin Walls wrote:
> Thanks Staffan, thanks Peter!
>
>
> On 02/05/13 14:11, Peter Allwin wrote:
>> Hi Kevin,
>>
>> Looks good!
>>
>> I've been looking into improving the quality of native stack traces 
>> on Windows using IDebugControl::GetStackTrace. This has the advantage 
>> of handling some FPO frames on x86 (a common source of these 
>> exceptions), as well as supporting AMD64 (walking the stack using RBP 
>> does not work at all on Windows/X64). There are still some issues to 
>> iron out before this change is ready, but your fix is a good start to 
>> what I'd like to accomplish.
>>
>>
>> Thanks,
>>
>> Peter
>>
>>> ------------------------------------------------------------------------
>>>
>>> 	Kevin Walls <mailto:kevin.walls at oracle.com>
>>> Tuesday, April 30, 2013 7:02 PM
>>>
>>>
>>> Hi,
>>>
>>> I'd like some review of this suggestion to fix:
>>> 6313816 SA windows unaligned address exception
>>>
>>> webrev:
>>> http://cr.openjdk.java.net/~kevinw/6313816/webrev/
>>>
>>> This bug is a long-standing annoyance, mainly shown by using jstack -m
>>>
>>> Already fixed on Linux with additional sanity checks on ebp/rbp 
>>> values in
>>> e.g. LinuxX86CFrame.sender()
>>>
>>> On Windows there isn't such a convenient place to put these checks, 
>>> as they
>>> call getAddressValue() which is only part of the specific debugger 
>>> interfaces
>>> such as LinuxDebugger, WindbgDebugger, etc.. and on Windows we use
>>> X86CFrame and AMD64CFrame.  These are constructed with only a
>>> CDebugger, there is no "WinXXXFrame" class - perhaps there should be!
>>>
>>> That's what  I've tried here, by renaming e.g. X86CFrame to 
>>> WinX86CFrame,
>>> and adding the extra sanity checks as we already have in 
>>> LinuxX86CFrame.
>>>
>>> As files have move thed diff isn't obvious, but in common with some 
>>> previous changes
>>> the new bits are x86 and x64 versions of these:
>>>
>>> + // Check alignment of rbp
>>> + if ( dbg.getAddressValue(rbp) % ADDRESS_SIZE != 0) {
>>> + return null;
>>> + }
>>> +
>>>
>>> and
>>>
>>> - if (nextRBP == null) {
>>> + if (nextRBP == null || nextRBP.lessThanOrEqual(rbp)) {
>>>
>>>
>>> This additional symmetry between the platforms seems to make sense, and
>>> should help any future changes.
>>>
>>> Thanks
>>> Kevin
>>>
>

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