[9] RFR(S): 8156659: assert(CodeCache::find_blob_unsafe(_pc) == _cb) failed: inconsistent

[Nils Eliasson]

Updated webrev with comment:
http://cr.openjdk.java.net/~neliasso/8156659/webrev.07

Regards,
Nils

On 2016-08-15 20:07, dean.long at oracle.com wrote:
> Looks good (if I can review my own patch).  How about a comment 
> explaining why we use O7 instead of the crash PC?
>
> dl
>
>
> On 8/15/16 8:28 AM, Nils Eliasson wrote:
>> Hi,
>>
>> After further investigation here is a new patch that needs your 
>> review. This code was suggested by Dean Long.
>>
>> Background:
>> This bug (JDK-8156659) was caused by the fix (JDK-8150821) which 
>> fixed a bug introduced by "JEP 270: Reserved Stack Areas for Critical 
>> Sections".
>>
>> JDK-8150821 changed the get_frame_at_stack_banging_point to create a 
>> fully initialized frame with both an SP and a FP. This frame 
>> constructor fetches the PC from the wrong stack position. The 
>> programs traps at the stack bang before the SAVE so the calling PC is 
>> still in O7. The frame tries to fetch the PC from I7 where it would 
>> have ended up after the SAVE.
>>
>> The original code that was fixed works, but has two problems. It 
>> first creates a frame with the wrong PC (the PC of the stack bang, 
>> but the SP of the caller), then gets the parent frame and iterates 
>> from there. The top most frame will be ignored and not checked properly.
>>
>> This patch uses the SP from the trap context and the contents of O7 
>> for PC. That is the SP and the PC for the caller of the method that 
>> traps on the stack bang.
>>
>> Testing:
>> Reproducer
>> Nightly on sparc (will be completed before push)
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8156659
>> Webrev: http://cr.openjdk.java.net/~neliasso/8156659/webrev.04/
>>
>> Regards,
>> Nils Eliasson
>>
>>
>>
>>
>>
>>
>>
>> On 2016-06-17 14:26, Vladimir Ivanov wrote:
>>> Why aren't other platforms affected?
>>>
>>> hotspot/src/cpu/x86/vm/frame_x86.cpp:
>>>
>>> frame frame::sender(RegisterMap* map) const {
>>> ...
>>>   assert(_cb == CodeCache::find_blob(pc()),"Must be the same");
>>>
>>> Best regards,
>>> Vladimir Ivanov
>>>
>>> On 6/17/16 1:52 PM, Nils Eliasson wrote:
>>>> Hi,
>>>>
>>>> Please review,
>>>>
>>>> Summary:
>>>> Test is provoking stack overflow errors and is running with
>>>> deoptimzeALot. The recently added method
>>>> "look_for_reserved_stack_annotated_method(...)" will traverse the 
>>>> stack
>>>> and encounter an deoptimized frame that triggers
>>>> "assert(CodeCache::find_blob_unsafe(_pc) == _cb, "inconsistent");". It
>>>> fails on deoptimzed frames where the pc is patched and need to be
>>>> changed to use raw_pc() to work correctly.
>>>>
>>>> Testing:
>>>> Running hotspot_all
>>>>
>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8156659
>>>> Webrev: http://cr.openjdk.java.net/~neliasso/8156659/webrev.02/
>>>>
>>>> Regards,
>>>> Nils Eliasson
>>
>