[M3devel] formsedit crash during startup sometimes?

[Jay]

RTHooks__CheckLoadTracedRef is I'm sure innocent. It gets called before any pointer deref, I guess. The problem is the pointer is sometimes null, sometimes not. And why that is is what we need to figure out.

 

 - Jay

 
> From: jay.krell at cornell.edu
> To: m3devel at elegosoft.com
> Date: Thu, 19 Mar 2009 07:47:47 +0000
> Subject: [M3devel] formsedit crash during startup sometimes?
> 
> 
> Formsedit on SOLgnu also crashes, sometimes, during startup.
> It doesn't seem to crash in a debugger, but you can load up the core dump after a crash. It looks very similar as on PPC_DARWIN.
> 
> 
> In both cases, it is dereferencing the value 4, just after calling RTHooks__CheckLoadTracedRef? Relevant? Coincidence?
> 
> 
> -bash-3.00$ uname -a
> SunOS unknown 5.10 Generic_118833-17 sun4u sparc SUNW,Sun-Blade-100
> -bash-3.00$ rm core
> -bash-3.00$ ./formsedit
> Segmentation Fault (core dumped)
> -bash-3.00$ dbx ./formsedit ./core
> ...
> t at 2 (l at 2) terminated by signal KILL (Killed)
> 0xfe3c03d0: ___nanosleep+0x0008: bcc,a,pt %icc,___nanosleep+0x18 ! 0xfe3c03e0
> (dbx) lwps
> l at 1 LWP suspended in lwp_yield()
> >l at 2 LWP suspended in ___nanosleep()
> l at 3 LWP suspended in __lwp_park()
> l at 4 LWP suspended in ___nanosleep()
> l at 11 LWP suspended in __lwp_park()
> l at 12 LWP suspended in __lwp_park()
> l at 13 LWP suspended in __lwp_park()
> o l at 27 signal SIGSEGV in ScrollerVBTClass__PaintViewWithShadows()
> l at 28 LWP suspended in __lwp_park()
> (dbx) lwp l at 27
> t at 27 (l at 27) stopped in ScrollerVBTClass__PaintViewWithShadows at 0xff1b945c
> 0xff1b945c: ScrollerVBTClass__PaintViewWithShadows+0x0340: ld [%g1], %g1
> (dbx) dis $pc - 0x10
> dbx: warning: unknown language, 'c' assumed
> 0xff1b941c: ScrollerVBTClass__PaintViewWithShadows+0x0300: inc -4, %g1
> 0xff1b9420: ScrollerVBTClass__PaintViewWithShadows+0x0304: ld [%g1], %g1
> 0xff1b9424: ScrollerVBTClass__PaintViewWithShadows+0x0308: sll %g1, 22, %g1
> 0xff1b9428: ScrollerVBTClass__PaintViewWithShadows+0x030c: srl %g1, 31, %g1
> 0xff1b942c: ScrollerVBTClass__PaintViewWithShadows+0x0310: btog 1, %g1
> 0xff1b9430: ScrollerVBTClass__PaintViewWithShadows+0x0314: and %g1, 255, %g1
> 0xff1b9434: ScrollerVBTClass__PaintViewWithShadows+0x0318: cmp %g1, 0
> 0xff1b9438: ScrollerVBTClass__PaintViewWithShadows+0x031c: bne,pt %icc,ScrollerVBTClass__Pain
> tViewWithShadows+0x334 ! 0xff1b9450
> 0xff1b943c: ScrollerVBTClass__PaintViewWithShadows+0x0320: nop
> 0xff1b9440: ScrollerVBTClass__PaintViewWithShadows+0x0324: ld [%fp - 24], %g1
> (dbx) dis
> 0xff1b9444: ScrollerVBTClass__PaintViewWithShadows+0x0328: mov %g1, %o0
> 0xff1b9448: ScrollerVBTClass__PaintViewWithShadows+0x032c: call RTHooks__CheckLoadTracedRef
> [PLT] ! 0xff2a9518
> 0xff1b944c: ScrollerVBTClass__PaintViewWithShadows+0x0330: nop
> 0xff1b9450: ScrollerVBTClass__PaintViewWithShadows+0x0334: ld [%fp + 68], %g3
> 0xff1b9454: ScrollerVBTClass__PaintViewWithShadows+0x0338: ld [%fp - 24], %g1
> 0xff1b9458: ScrollerVBTClass__PaintViewWithShadows+0x033c: inc 4, %g1
> 0xff1b945c: ScrollerVBTClass__PaintViewWithShadows+0x0340: ld [%g1], %g1
> 0xff1b9460: ScrollerVBTClass__PaintViewWithShadows+0x0344: st %g1, [%fp - 180]
> 0xff1b9464: ScrollerVBTClass__PaintViewWithShadows+0x0348: add %fp, -40, %g1
> 0xff1b9468: ScrollerVBTClass__PaintViewWithShadows+0x034c: add %fp, -180, %g2
> (dbx) print $g1
> $g1 = 4ULL
> (dbx)
> 
> I believe it is on the last line of the function, the PaintTint call (due to what PPC_DARWIN showed).
> 
> 
> PROCEDURE PaintViewWithShadows (v: T) =
> VAR
> dom : Rect.T;
> stripe: Rect.T;
> r : Rect.T;
> f : Rect.Partition;
> BEGIN
> dom := VBT.Domain(v);
> stripe := ComputeStripe(v, dom);
> (* Paint the scroll. We are careful not to draw the area of the
> trough that will be covered by the stripe. This helps reduce
> the flicker. *)
> r := Rect.Inset(dom, v.shadowPixels);
> ShadowPaint.Border(v, Region.Full, v.shadow, Shadow.Style.Lowered,
> r, dom);
> Rect.Factor(r, stripe, f, 0, 0);
> FOR i := FIRST(f) TO LAST(f) DO
> IF i # 2 AND NOT Rect.IsEmpty(f[i]) THEN
> VBT.PaintTint(v, f[i], v.troughColor);
> END;
> END;
> (* Paint the stripe. *)
> r := Rect.Inset(stripe, v.shadowPixels);
> ShadowPaint.Border(v, Region.Full, v.shadow, Shadow.Style.Raised,
> r, stripe);
> VBT.PaintTint(v, r, v.shadow.bg);
> END PaintViewWithShadows;
> 
> 
> I'm somewhat just showing people how to get started debugging it, in case folks are as afraid of command line debuggers as I used to be.
> 
> 
> - Jay
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