RFR(XS): JDK-8068655 frame::safe_for_sender() computes incorrect sender_sp value for interpreted frames

[Frederic Parain]

Forgot new webrev:

http://cr.openjdk.java.net/~fparain/8068655/webrev.02/

Fred

On 29/01/2015 19:53, Frederic Parain wrote:
> Dan,
>
> Thank you for your review.
>
> My answers are below.
>
> On 29/01/2015 19:24, Daniel D. Daugherty wrote:
>> On 1/29/15 8:05 AM, Frederic Parain wrote:
>>> Hi Dean,
>>>
>>> When unextended_sp is not specified, it is set to the sp value.
>>>
>>> However, after your question, I realized that my fix was not
>>> correct but worked because the is_interpreted_frame_valid() had
>>> a bug too, it uses sp() where unextended_sp() should be used.
>>>
>>> Checking the history of these files, is_interpreted_frame_valid() has
>>> been written before the distinction between raw sp and unextended sp
>>> has been introduced in the frame class. Unfortunately, when
>>> unextended_sp was added, is_interpreted_frame_valid() has not been
>>> updated.
>>>
>>> Here's a new webrev where safe_for_sender computes both raw_sp and
>>> unextended_sp, and is_interpreted_frame_valid() checks the frame
>>> size using unextended_sp instead of raw sp.
>>>
>>> http://cr.openjdk.java.net/~fparain/8068655/webrev.01/
>>
>> src/cpu/x86/vm/frame_x86.cpp
>>      nit: line 158: saved_fp = (intptr_t*)*(sender_sp -
>> frame::sender_sp_offset);
>>          Please add a space between the cast and the ptr deref, i.e.:
>>
>>          line 158: saved_fp = (intptr_t*) *(sender_sp -
>> frame::sender_sp_offset);
>
> Done
>
>>      line 214: frame sender(sender_sp, saved_fp, sender_pc);
>>          This line is not changed based on the assumption that
>>          (sender_sp == sender_unextended_sp). Do you want to
>>          assert() that just before line 214?
>
> After writing this assert it looked strange to me.
> I removed it and used the 4 arguments constructor to pass the
> unextended_sp computed line 154. It makes the code more regular
> between interpreted and not interpreted frames.
>
>>      line 580: if (fp() - unextended_sp() > 1024 + ...
>>          Previous to this line, the "stack pointer" checks all use sp().
>>          A short comment explaining the switch to unextended_sp() would
>>          be good here.
>
> Done
>
>> Thumbs up. Your choice on whether to address my (very) minor
>> comments on this round.
>
> Thanks Dan,
>
> Fred
>
>>>
>>> I also added more comments.
>>>
>>> Note that I only modify one test in is_interpreted_frame_valid().
>>> Use of sp() or unextended_sp() could be discussed for each test,
>>> but in their current form they are wrong.
>>>
>>> Thanks,
>>>
>>> Fred
>>>
>>> On 26/01/2015 20:40, Dean Long wrote:
>>>> In sender_for_interpreter_frame(), we set the raw sender_sp but also
>>>> unextended_sp.  Should
>>>> safe_for_sender() be doing the same?
>>>>
>>>> dl
>>>>
>>>> On 1/26/2015 6:40 AM, Frederic Parain wrote:
>>>>> Greetings,
>>>>>
>>>>> Please review this small fix in the frame verification code.
>>>>> The bug report includes a detailed description of the issue.
>>>>>
>>>>> CR:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8068655
>>>>>
>>>>> Webrev:
>>>>> http://cr.openjdk.java.net/~fparain/8068655/webrev.00/
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Fred
>>>>>
>>>>
>>>
>>
>

-- 
Frederic Parain - Oracle
Grenoble Engineering Center - France
Phone: +33 4 76 18 81 17
Email: Frederic.Parain at oracle.com