Re: [Gcl-devel] Re: BFD relocations

[Camm Maguire <camm at enhanced dot com>]

Greetings!

Daniel Jacobowitz <drow@mvista.com> writes:

> 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.
> 

Thanks for this suggestion!  I'm afraid I'm a neophyte wrt cache
flushing.  Is there a specific assembly instruction I should add, or
do I flush via a read through the .text and .(s)data sections, or a
copy to some distant memory? 

Thanks again!

> > 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
> 
> 

-- 
Camm Maguire			     			camm@enhanced.com
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