Cog on Mac. Problems with mprotect()?

>
> I have no idea why mprotect() returns -1 (failure),
> and then perror prints following:
>
> mprotect(x,y,PROT_READ | PROT_WRITE | PROT_EXEC): Cannot allocate memory
> mprotect(x,y,PROT_READ | PROT_WRITE): Invalid argument
>
> While it looks like Cog VM runs stable at the same time. But it
> crashing at crucial point of NB tests,
> needless to say, that same tests are running on other platforms and
> everything ok.
>
> So, there is something wrong with it. The only question is what :)
>
> While in general, i can run native code, generated by NB, which means
> that memory execution is enabled,
> something leads to memory access error during GC, in test which
> checking if relocated native code will continue to run from
> expected point as if it was not relocated.
> What is strange with this thing, that i expected to see errors in my
> code. But why it crashes in the middle of pow() function,
> which is called from initializeMemoryFirstFree()??
>
> Thread 0 Crashed:  Dispatch queue: com.apple.main-thread
> 0   libSystem.B.dylib             0x98273176 __kill + 10
> 1   libSystem.B.dylib             0x98273168 kill$UNIX2003 + 32
> 2   libSystem.B.dylib             0x9830589d raise + 26
> 3   libSystem.B.dylib             0x9831b9bc abort + 93
> 4   com.teleplace.Teleplace       0x00090f86 error + 86
> 5   libSystem.B.dylib             0x9827846b _sigtramp + 43
> 6   ???                           0xffffffff 0 + 4294967295
> 7   com.teleplace.Teleplace       0x0010d468 initializeMemoryFirstFree + 184
> 8   com.teleplace.Teleplace       0x00113381 incCompBody + 1057
> 9   com.teleplace.Teleplace       0x001229ec fullGC + 1356
> 10  ???                           0x17203026 0 + 387985446
> 11  com.teleplace.Teleplace       0x0014fe98 primitiveNativeCall + 216
> 12  com.teleplace.Teleplace       0x00132422 executeNewMethod + 130
> 13  com.teleplace.Teleplace       0x00133111
> primitiveExecuteMethodArgsArray + 497
> 14  com.teleplace.Teleplace       0x001365f6 interpret + 1078
> 15  com.teleplace.Teleplace       0x0013d94e
> enterSmalltalkExecutiveImplementation + 110
> 16  com.teleplace.Teleplace       0x0013db81 initStackPagesAndInterpret + 545
> 17  com.teleplace.Teleplace       0x00079494 EventLoopEventHandler + 132
>
>
> The stack frame #11 is a primitive which calls my native code (frame #10)
> then the native code deliberately calls fullGC() (frame #9)
> and it seems like works, till something bad happen in pow() function,
> called by initializeMemoryFirstFree()
>
> Here the code near call to pow() function:
>
> 0x0010d43d  <+0141>  shr    %ebx
> 0x0010d43f  <+0143>  add    $0x1,%eax
> 0x0010d442  <+0146>  mov    0x182be8,%edi
> 0x0010d448  <+0152>  add    %ebx,%eax
> 0x0010d44a  <+0154>  cvtsi2sd %eax,%xmm0
> 0x0010d44e  <+0158>  movsd  %xmm0,0x8(%esp)
> 0x0010d454  <+0164>  movl   $0x0,(%esp)
> 0x0010d45b  <+0171>  movl   $0x40000000,0x4(%esp)
> 0x0010d463  <+0179>  call   0x163a84 <dyld_stub_pow>
> 0x0010d468  <+0184>  fstpl  -0x30(%ebp)
> 0x0010d46b  <+0187>  cvttsd2si -0x30(%ebp),%eax
> 0x0010d470  <+0192>  add    -0x1c(%ebp),%eax
>
> and here the code where it crashing:
>
> 0x98262f56  <+1078>  jmp    0x98262b66 <pow$fenv_access_off+70>
> 0x98262f5b  <+1083>  movapd %xmm2,%xmm1
> 0x98262f5f  <+1087>  andpd  0x13e049(%ebx),%xmm1
> 0x98262f67  <+1095>  movapd %xmm2,%xmm0
> 0x98262f6b  <+1099>  andpd  0x13e079(%ebx),%xmm0
> *** 0x98262f73  <+1107>  movapd %xmm0,-0x78(%ebp)
> 0x98262f78  <+1112>  movapd %xmm1,%xmm0
> 0x98262f7c  <+1116>  lea    0x13e069(%ebx),%esi
> 0x98262f82  <+1122>  addpd  (%esi),%xmm0
> 0x98262f86  <+1126>  andpd  -0x78(%ebp),%xmm0
> 0x98262f8b  <+1131>  movapd %xmm0,-0x78(%ebp)
> 0x98262f90  <+1136>  paddq  0x13cfb9(%ebx),%xmm1
>
>
> i can only guess, that it either a problem with mprotect(),
> or that due to heavy use of MMX/SSE instructions, i miss some
> precautions (not saving some registers/processor state) between the
> calls in my code.
> Any ideas?
>
> --
> Best regards,
> Igor Stasenko AKA sig.

> thanks
>
> mariano
>
> 2010/12/6 Igor Stasenko <[hidden email]>
>>
>> OK, i changed
>>
>> interpreterAllocationReserveBytes
>>        | availableBytesPerPage maxFramesPerPage |
>>        availableBytesPerPage := self stackPageByteSize - self
>> stackLimitOffset - self stackPageHeadroom.
>>        maxFramesPerPage := availableBytesPerPage / BytesPerWord // MFrameSlots.
>>        ^2 raisedTo: (maxFramesPerPage * LargeContextSize * numStackPages) highBit
>>
>> to:
>>
>> interpreterAllocationReserveBytes
>>        | availableBytesPerPage maxFramesPerPage |
>>        availableBytesPerPage := self stackPageByteSize - self
>> stackLimitOffset - self stackPageHeadroom.
>>        maxFramesPerPage := availableBytesPerPage / BytesPerWord // MFrameSlots.
>>        ^2 << ((maxFramesPerPage * LargeContextSize * numStackPages) highBit -1)
>>
>>
>> which is equal, except that latter its not using pow() function and
>> somehow this no longer crashing the VM.
>> The only conclusion i can make that this is really have nothing to do
>> with mprotect() and other mmap() stuff.
>>
>> I can only guess, that xcode doing some aggressive optimization,
>> violating calling conventions, or in some other way the fullGC is
>> optimized in a way
>> that it expected to be called from certain places (but obviously not
>> from native code generated on the fly).
>>
>> That's really weird.
>>
>> --
>> Best regards,
>> Igor Stasenko AKA sig.
>
>
>