[Vm-dev] [BUG] CogVM crash on Windows

[Eliot Miranda]

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


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
>
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