Re: [Gcl-devel] Re: BFD relocations

[Camm Maguire]

Greetings!

Daniel Jacobowitz <address@hidden> 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                                            address@hidden
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