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

[Kevin Walls]

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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