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

[Shrikanth Kamath]

> 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.

Thanks,
--
Shrikanth R K