DTrace: stack() does not print kernel module functions for i386

[Mark Johnston]

On Mon, Nov 24, 2014 at 06:36:26PM -0800, Shrikanth Kamath wrote:
> > The suggested patch doesn't seem quite right; there are other functions
> > in dt_module.c with the same assignment (i.e.
> > "is_elf_obj = ehdr.e_type == ET_REL"), but the same modification is not
> > correct in all cases - fixing it everywhere breaks stack() again - and
> > "is_elf_obj" seems like the wrong name if DSOs are counted as well.
> >
> > The root of the problem is that dmp->dm_*_va offsets don't have the kld
> > load address taken into account on i386, since they're currently set based
> > only on the ELF section addresses. This is handled by
> > dmp->dm_reloc_offset for symbols, but that's a separate case.
> >
> > When is_elf_obj is true, we include the load address when setting the
> > dmp->dm_*_va fields. I suggest we do that unconditionally, and only set
> > elements of dmp->dm_sec_offsets if is_elf_obj is true. This fixes the
> > bug for me on i386. Any opinions?
> >
> > Thanks,
> > -Mark
> >
> > diff --git a/cddl/contrib/opensolaris/lib/libdtrace/common/dt_module.c b/cddl/contrib/opensolaris/lib/libdtrace/common/dt_module.c
> > index e3905c1..9dd52b5 100644
> > --- a/cddl/contrib/opensolaris/lib/libdtrace/common/dt_module.c
> > +++ b/cddl/contrib/opensolaris/lib/libdtrace/common/dt_module.c
> > @@ -1211,13 +1211,13 @@ dt_module_update(dtrace_hdl_t *dtp, struct kld_file_stat *k_stat)
> >  #if defined(__FreeBSD__)
> >                 if (sh.sh_size == 0)
> >                         continue;
> > -               if (is_elf_obj && (sh.sh_type == SHT_PROGBITS ||
> > -                   sh.sh_type == SHT_NOBITS)) {
> > +               if (sh.sh_type == SHT_PROGBITS || sh.sh_type == SHT_NOBITS) {
> >                         alignmask = sh.sh_addralign - 1;
> >                         mapbase += alignmask;
> >                         mapbase &= ~alignmask;
> >                         sh.sh_addr = mapbase;
> > -                       dmp->dm_sec_offsets[elf_ndxscn(sp)] = sh.sh_addr;
> > +                       if (is_elf_obj)
> > +                               dmp->dm_sec_offsets[elf_ndxscn(sp)] = sh.sh_addr;
> >                         mapbase += sh.sh_size;
> >                 }
> >  #endif
> 
> Hello Mark,
>     I tested the patch and works good, did some basic testing. Marcel
> too pointed to the other occurrence of is_elf_obj in the file and that
> it should not include ET_DYN which is when I realized  it was not the
> right thing to do, i was trying to read up more on this,  guess this
> patch takes care of it. Thanks for fixing this.

I've committed it as r275011. Thanks for the report.