[Vm-dev] [BUG] CogVM crash on Windows
Igor Stasenko
siguctua at gmail.com
Wed Aug 25 03:11:01 UTC 2010
On 25 August 2010 04:39, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>
> Hi Levente,
> essentially correct. The bug was caused by an incorrect asm. Changing
> # define BYTE_SWAP(w) __asm__("bswap %%eax" : "=r" (w) : "r" (w))
> # define WORD_SWAP(w) __asm__("roll $16, %%eax" : "=r" (w) : "r" (w))
> to
> # define BYTE_SWAP(w) __asm__("bswap %0" : "=r" (w) : "r" (w))
> # define WORD_SWAP(w) __asm__("roll $16, %0" : "=r" (w) : "r" (w))
> in platforms/win32/vm/sqWin32Window.c's byte & word image reversal code fixes it. This worked back on 2.95.x because it always chose $eax as the register for the value variable in
> unsigned int value = *srcPixPtr++;
> but gcc 3.x is more devious.
> I've updated svn and will upload a new engine soon.
> thanks,
> Eliot
>
Hmm.. interesting, how changing a byte order could cause a crash?
A windows blitter using byte reversal logic when blitting a big-endian
forms on windows GDI (since on windows its little-endian,
it swaps form's bits, then copying bits, and then swaps back again)..
but still i don't understand how this may cause a crash.. it may cause
problems with seeing anything correct on a screen.
> On Sun, Aug 22, 2010 at 1:56 PM, Levente Uzonyi <leves at elte.hu> wrote:
>>
>> Hi,
>>
>>
>> evaluating [Display newDepth: x] where the value of x is 1, 4, 8 or 16 crashes the VM. No crash dump is written. If x is 2, -1, -2 or -4, then the image informs me that the depth is not available on the system. If x is -8 or -16 then the code works. For the x=16 case gdb shows the following:
>>
>> Program received signal SIGSEGV, Segmentation fault.
>> reverse_image_words (dst=0x1450eca4, src=0x1450eca4, depth=0, width=1272,
>> rect=0x561e60) at ../platforms/win32/vm/sqWin32Window.c:1875
>> 1875 unsigned int value = *srcPixPtr++;
>> (gdb) where
>> #0 reverse_image_words (dst=0x1450eca4, src=0x1450eca4, depth=0, width=1272,
>> rect=0x561e60) at ../platforms/win32/vm/sqWin32Window.c:1875
>> #1 0x0043f61a in ioShowDisplay (dispBits=340847780, width=1272, height=745,
>> depth=16, affectedL=0, affectedR=1000, affectedT=0, affectedB=0)
>> at ../platforms/win32/vm/sqWin32Window.c:2324
>> #2 0x00403270 in displayBitsOfLeftTopRightBottom (aForm=-719257650, l=0,
>> t=0, r=1272, b=745) at ../src/vm/gcc3x-cointerp.c:13701
>> #3 0x00405ff9 in fullDisplayUpdate () at ../src/vm/gcc3x-cointerp.c:16777
>> #4 0x0044093a in MainWndProcW (hwnd=0xf05f6, message=15, wParam=0, lParam=0)
>> at ../platforms/win32/vm/sqWin32Window.c:447
>> #5 0x75fef8d2 in USER32!GetMessageW ()
>> from /cygdrive/c/Windows/system32/user32.dll
>> #6 0x75fef794 in USER32!GetWindowLongW ()
>> from /cygdrive/c/Windows/system32/user32.dll
>> #7 0x004403dc in sqLaunchDrop ()
>> at ../platforms/win32/vm/sqWin32Window.c:2773
>> #8 0x75ff0817 in USER32!ReleaseDC ()
>> from /cygdrive/c/Windows/system32/user32.dll
>> #9 0x75ff0a65 in USER32!GetWindowThreadProcessId ()
>> from /cygdrive/c/Windows/system32/user32.dll
>> #10 0x776a99ce in ntdll!LdrEnumResources ()
>> from /cygdrive/c/Windows/system32/ntdll.dll
>> #11 0x00ace008 in ?? ()
>> #12 0x00000018 in ?? ()
>> ---Type <return> to continue, or q <return> to quit---
>> #13 0x00ace058 in ?? ()
>> #14 0x776a9980 in ntdll!LdrDisableThreadCalloutsForDll ()
>> from /cygdrive/c/Windows/system32/ntdll.dll
>> #15 0x0204c1d8 in ?? ()
>> #16 0x0000000f in ?? ()
>> #17 0x00000000 in ?? ()
>> (gdb) info registers
>> eax 0xd520ffce -719257650
>> ecx 0x3 3
>> edx 0x0 0
>> ebx 0x1f4 500
>> esp 0xacd5b4 0xacd5b4
>> ebp 0x0 0x0
>> esi 0x1511a000 353476608
>> edi 0x1511a000 353476608
>> eip 0x43ed0c 0x43ed0c <reverse_image_words+353>
>> eflags 0x10216 [ PF AF IF RF ]
>> cs 0x1b 27
>> ss 0x23 35
>> ds 0x23 35
>> es 0x23 35
>> fs 0x3b 59
>> gs 0x0 0
>>
>> It may be a compiler bug, because the 4.0.2 SqueakVM doesn't have this issue. It's a bit suspicious that depth is 0 here:
>> #0 reverse_image_words (dst=0x1450eca4, src=0x1450eca4, depth=0, width=1272,
>> rect=0x561e60) at ../platforms/win32/vm/sqWin32Window.c:1875
>> but the value of depth is known at compilation time (16), so it may be some compiler "magic".
>> Here are the values of the variables in the method:
>> (gdb) p dst
>> $2 = (unsigned int *) 0x1450eca4
>> (gdb) p src
>> $3 = (unsigned int *) 0x1450eca4
>> (gdb) p depth
>> $4 = 0
>> (gdb) p width
>> $5 = 1272
>> (gdb) p rect
>> $6 = (RECT *) 0x561e60
>> (gdb) p rect->left
>> $7 = 0
>> (gdb) p rect->right
>> $8 = 1000
>> (gdb) p rect->top
>> $9 = 0
>> (gdb) p rect->bottom
>> $10 = 745
>> (gdb) p pitch
>> $11 = 353476608
>> (gdb) p first
>> $12 = 3
>> (gdb) p last
>> No symbol "last" in current context.
>> (gdb) p nWords
>> $13 = 500
>> (gdb) p delta
>> $14 = 0
>> (gdb) p yy
>> $15 = 0
>> (gdb) p srcPixPtr
>> $16 = (DWORD *) 0x1511a000
>> (gdb) p dstPixPtr
>> $17 = (DWORD *) 0x1511a000
>> (gdb) p i
>> $18 = -719257650
>> (gdb) p value
>> $19 = 0
>>
>>
>> Cheers,
>> Levente
>
>
>
--
Best regards,
Igor Stasenko AKA sig.
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