Re: egcs 10-31 and UnixWare

[Robert Lipe <robertl at dgii dot com>]

>   > Breakpoint 2, 0x800196c4 in exit ()
>   > (gdb) cont
>   > Continuing.
>   > 
>   > Breakpoint 3, 0x80485a6 in __do_global_dtors_aux ()
>   > (gdb) cont
>   > Continuing.
>   > --count
>   > --count
>   > 
>   > Breakpoint 2, 0x800196c4 in exit ()
>   > (gdb) cont
>   > Continuing.
> Wild.  That shouldn't be happening....  I think we've got something
> to work backwards from now.

I didn't think so. :-)

> What about recompiling the crt* files with -g -O0 so you can get
> control of do_global_dtors_aux and possibly see how in the hell
> it's calling exit!


> Hmmm, maybe EH_FRAME_SECTION_ASM_OP isn't defined, and do_global_dtors_aux
> is actually finishing, which would drop us back into our friend fini_dummy.

It's definitely defined on OpenServer.  When I disassemble
the binary, I can see the call to __de


08048580 <__do_global_dtors_aux>:
 8048580:       55              pushl  %ebp
 8048581:       8b ec           movl   %esp,%ebp
 8048583:       53              pushl  %ebx
 8048584:       e8 00 00 00 00  call   8048589 <__do_global_dtors_aux+9>
 8048589:       5b              popl   %ebx
 804858a:       81 c3 fb 20 00  addl   $0x20fb,%ebx
 804858f:       00
 8048590:       eb 15           jmp    80485a7 <__do_global_dtors_aux+27>
 8048592:       8b ff           movl   %edi,%edi
 8048594:       8b 83 94 fa ff  movl   0xfffffa94(%ebx),%eax
 8048599:       ff
 804859a:       8d 50 04        leal   0x4(%eax),%edx
 804859d:       89 93 94 fa ff  movl   %edx,0xfffffa94(%ebx)
 80485a2:       ff
 80485a3:       8b 00           movl   (%eax),%eax
 80485a5:       ff d0           call   *%eax
 80485a7:       8b 83 94 fa ff  movl   0xfffffa94(%ebx),%eax
 80485ac:       ff
 80485ad:       83 38 00        cmpl   $0x0,(%eax)
 80485b0:       75 e2           jne    8048594 <__do_global_dtors_aux+14>
 80485b2:       8d 83 c4 fa ff  leal   0xfffffac4(%ebx),%eax
 80485b7:       ff
 80485b8:       50              pushl  %eax
 80485b9:       e8 f2 08 00 00  call   8048eb0 <__deregister_frame>
 80485be:       8b 5d fc        movl   0xfffffffc(%ebp),%ebx
 80485c1:       8b e5           movl   %ebp,%esp
 80485c3:       5d              popl   %ebp
 80485c4:       c3              ret
 80485c5:       8d 76 00        leal   0x0(%esi),%esi

It's a little wierd that there's an opcode after the ret.

I don't think it's falling through.  It looks like the problem is that
we're in an atexit() function (__do_global_dtors_aux) and it's calling 
the destructor and the destructor is calling exit.   Since exit() will
rip through the atexit() functions, isn't this bad?


Currently, the makefile generates these files liek this:

./xgcc -B./  -DIN_GCC    -O2 -g -I./include  -I. -I../../egcs-971023/gcc -I../..
/egcs-971023/gcc/config  -g0 \
  -finhibit-size-directive -fno-inline-functions -fno-exceptions  \
  -c ../../egcs-971023/gcc/crtstuff.c -DCRT_BEGIN -o crtbegin.o
./xgcc -B./  -DIN_GCC    -O2 -g -I./include  -I. -I../../egcs-971023/gcc -I../..
/egcs-971023/gcc/config  -g0 \
  -finhibit-size-directive -fno-inline-functions -fno-exceptions  \
  -c ../../egcs-971023/gcc/crtstuff.c -DCRT_END -o crtend.o


begin slight tangent...

If I change '-g0' to '-g', it dies during the build:

./xgcc -B./  -DIN_GCC    -O2 -g -I./include  -I. -I../../egcs-971023/gcc -I../..
/egcs-971023/gcc/config  -g \
  -finhibit-size-directive -fno-inline-functions -fno-exceptions  \
  -c ../../egcs-971023/gcc/crtstuff.c -DCRT_BEGIN -o crtbegin.o
/usr/tmp/cca003Pz.s:279:defined relocatable values from the same section require
d, op -
/usr/tmp/cca003Pz.s:287:defined relocatable values from the same section require
d, op -
/usr/tmp/cca003Pz.s:410:defined relocatable values from the same section require
d, op -
/usr/tmp/cca003Pz.s:418:defined relocatable values from the same section require
d, op -


If also I change BOOT_CFLAGS to -O0, it makes no difference.

Looking at the assembly file, it's croaking  on the references to L_text_b
        .section        .line
        .4byte  148     / /crtstuff.c:148
        .2byte  0xffff
        .4byte  .L_LC12-.L_text_b
        .previous
        call __do_global_dtors_aux
.L_LC13:

L_text_b. is in the section .debug_aranges, .L_LC12 is in .text.
This seems to happen in the calls to asm(FINI_SECTION_ASM_OP)

If I run -g to -g1, it builds.



...end debug tangent.

Building crtstuff with this level of debugging makes the 
backtrace more clearly frightening.


Program received signal SIGABRT, Aborted.
0x80019733 in _kill ()
(gdb) where
#0  0x80019733 in _kill ()
#1  0x8003df84 in abort ()
#2  0x8001d46f in _exithandle ()
#3  0x8003df56 in abort ()
#4  0x8001d46f in _exithandle ()
#5  0x800196d6 in exit ()
#6  0x80485a7 in __do_global_dtors_aux ()
#7  0x804905d in .fini ()
#8  0x800196d6 in exit ()


RJL