SIGILL crashes JVM on PPC64 LE

[Gustavo Romero]

Hi Volker

Thanks for inspecting the Hotspot crash log.

At the moment it's no possible, AFIAK - and as I could try - to run
Cassandra on OpenJDK 9. It will hit another missing class issue before
it runs into the SIGILL issue.

I'm still trying to reproduce it with an easy test case.

However, I provide the C2 compiled method disasm:

hs_err log:
http://hastebin.com/raw/orufukacos

hs_err method disasm:
http://hastebin.com/raw/owoxamodok

Source for one of the four problematic classes that will crash JVM when
compiled (we can see them in hs_err method disasm comments):
java/org/apache/cassandra/db/rows/NativeCell.java#L133
https://goo.gl/Uefq8Y

Thanks for letting me know that `isel` is never emitted.

Thank you!

Best regards,
Gustavo

On 12-05-2016 09:39, Volker Simonis wrote:
> And I forgot to mention: I've checked and we don't emit vsel
> instructions in jdk8 on ppc. So it must be a coincidence that changing
> the endianess of the offending instruction yields a valid 'vsel'
> instruction.
> 
> 
> 
> On Thu, May 12, 2016 at 2:26 PM, Volker Simonis
> <volker.simonis at gmail.com> wrote:
>> Hi Gustavo,
>>
>> thanks for the bug report. The hs_err file you provided indicates that
>> this crash happened with Ubuntu's openjdk 8 version. Can you still
>> reproduce this with the the newest jdk9 builds?
>>
>> Also, I can see from the hs_err file that the crash happened in the C2
>> compiled method java.util.TimSort.countRunAndMakeAscending which
>> doesn't seem to be related to nio and unsafe.
>>
>> Ideally, you could post an easy test case to reproduce the problem. If
>> that's not possible, it would be helpful if you could post the output
>> of a failing run with
>> "-XX:CompileCommand=print,java.util.TimSort::countRunAndMakeAscending
>> -XX:CompileCommand=option,java.util.TimSort::countRunAndMakeAscending,PrintOptoAssembly".
>> In order to get the disassembly output for compiled methods you have
>> to build the hsdis library from hotspot/src/share/tools/hsdis (it has
>> a README with build instructions).
>>
>> Regards,
>> Volker
>>
>>
>> On Thu, May 12, 2016 at 12:32 AM, Gustavo Romero
>> <gromero at linux.vnet.ibm.com> wrote:
>>> Hi
>>>
>>> I'm getting a nasty SIGILL that crashes the JVM on PPC64 LE.
>>>
>>> hs_err log:
>>> http://hastebin.com/raw/fovagunaci
>>>
>>> The application employs methods from both java.nio.ByteBuffer and
>>> sun.misc.Unsafe classes in order to write and read from an allocated buffer.
>>>
>>> A interesting thing is that after debugging the instruction that caused the
>>> said SIGILL:
>>>
>>>    0x3fff902839a4:      cmpwi   cr6,r17,0
>>>    0x3fff902839a8:      beq     cr6,0x3fff90283ae4
>>>    0x3fff902839ac:      .long 0xea2f0013 <============ illegal instruction
>>>    0x3fff902839b0:      add     r15,r15,r17
>>>    0x3fff902839b4:      add     r14,r17,r14
>>>
>>> I found that when its endianness is changed it turns out to be a valid
>>> instruction: vsel v24,v0,v5,v31
>>>
>>> However, I'm still unable to determine if it's an application issue, something
>>> with JVM unsafe interface code, or something else.
>>>
>>> Any clue on how to narrow down this SIGILL?
>>>
>>> Thank you!
>>>
>>> Regards,
>>> Gustavo
>>>
>