[Vm-dev] Cog on Mac. Problems with mprotect()?

[John M McIntosh]

mprotect  likely returns Invalid Argument because the range is wrong. 

I traded some notes with Eliot on this in August, you'll need to chase him to see what we decided to change in order to avoid the problem.
Yes this is the for mprotect(x,y,PROT_READ | PROT_WRITE): Invalid argument  I guess... 

"This is the mprotect for the squeak heap 
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that works with my change to subtract out the cogCodeSize

	sqMakeMemoryNotExecutableFromTo(((usqInt)heapBase), ((usqInt)GIV(memoryLimit))-GIV(cogCodeSize));
But the 
	sqMakeMemoryNotExecutableFromTo(((usqInt)theStackMemory), (((usqInt)theStackMemory)) + stackPagesBytes);

fails

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mprotect(x,y,PROT_READ | PROT_WRITE): Cannot allocate memory"


On 2010-12-05, at 3:48 PM, Igor Stasenko wrote:

> 
> 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.

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John M. McIntosh <johnmci at smalltalkconsulting.com>   Twitter:  squeaker68882
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