new ppc32 GOT/PLT support for mcount

[Alan Modra]

On Sat, Jun 11, 2005 at 10:58:52AM +0200, Jakub Jelinek wrote:
> On Thu, Jun 09, 2005 at 05:31:56PM -0500, Steve Munroe wrote:
[about _mcount]
> This looks wrong, for multiple reasons:

Yes, my fault.  When looking at _mcount for ppc, I noticed that gcc
carefully sets up r0 to point at a count var, and the ppc _mcount stub
in glibc commented about the r0 param too.  Of course, glibc's _mcount
needs no count var, but I'd forgotten that.  Now, if glibc's _mcount
really did need a pointer to the counter, then we'd be in trouble
because the new lazy sym resolver call stub trashes r0.  ie. we couldn't
call _mcount via the plt.  So I thought we'd need to move _mcount to
libc_nonshared.a.  I put a fixme in my new plt/got libc patch, and told
Steve about the _mcount "problem".  Really, all that needs doing is
fixing the comment in ppc-mcount.S, and cleaning up
sysdeps/powerpc/powerpc32/sysdep.h.  Sorry for any wasted effort.  :-(

I'll generate a new glibc patch.

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre