Re: [Gcl-devel] Re: BFD relocations

[Daniel Jacobowitz]

On Tue, Jun 04, 2002 at 05:33:57PM -0400, Camm Maguire wrote:
> Greetings. and thank you again for your reply!
> 
> In brief, I can relocate, but I get SIGILL on apparently correctly
> relocated code when trying to execute.
> 
> I would be very appreciative if you might save me the pain of
> searching through the kernel sources and brief me on what raises
> SIGILL on ppc.  I'm already aware of divide by zero, and of course an
> unknown opcode, but neither seems to be the case here.  Alignment?

Cache.  Are you explicitly flushing the data and instruction caches
over the entire loaded range?  If not, you absolutely should try that.

> Detail:
> 
> gcl builds fine on ppc with bfd relocations, including gcl-tk.  When
> building maxima-5.6 with it, which involves loading several object
> files, I've gotten SIGILL in the following two places when executing
> code from kclmac.o:
> 
> objdump -d kclmac.o |head -40l
> 
> kclmac.o:     file format elf32-powerpc
> 
> Disassembly of section .text:
> 
> 00000000 <init_kclmac>:
> ->   0:       94 21 ff f0     stwu    r1,-16(r1)
>    4: 7c 08 02 a6     mflr    r0
>    8: 90 01 00 14     stw     r0,20(r1)
>    c: 3c 60 00 00     lis     r3,0
>   10: 38 63 00 00     addi    r3,r3,0
>   14: 4c c6 31 82     crclr   4*cr1+eq
>   18: 48 00 00 01     bl      18 <init_kclmac+0x18>
>   1c: 80 01 00 14     lwz     r0,20(r1)
> ->  20:       7c 08 03 a6     mtlr    r0
>   24: 38 21 00 10     addi    r1,r1,16
>   28: 4e 80 00 20     blr
> 
> 0000002c <L1>:
>   2c: 94 21 ff e0     stwu    r1,-32(r1)
>   30: 7c 08 02 a6     mflr    r0

Those two spots are both apparently undistinguished, and 32 bytes
apart.  Coincidence?  I think not.


-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer