[Linux-ia64] Re: insmod bug causes kernel unwind failures for module text

[Dave Anderson <anderson@redhat.com>]

Keith,

Unfortunately the patch won't work, at least in the context of the current
kernel code, because the following range check in ia64_module_init() causes
the insmod to fail:

  if (!mod_bound(archdata->segment_base, 0, mod))
  {
        printk(KERN_ERR "module_arch_init: archdata->unw_table out of bounds.\n");
        return 1;
  }

mod_bound() doesn't include the module struct as part of the module:

  #define mod_bound(p, n, m) ((unsigned long)(p) >= ((unsigned long)(m) +
  ((m)->size_of_struct)) && \
                   (unsigned long)((p)+(n)) <= (unsigned long)(m) + (m)->size)

Dave Anderson




Keith Owens wrote:

> On Thu, 25 Jul 2002 13:38:27 -0400,
> Dave Anderson <anderson@redhat.com> wrote:
> >There is a bug in the initialization of the unw_table_entry structures for
> >all kernel modules, such that any unwind operation that comes upon a kernel
> >module text address will fail to find its associated unwind info data in
> >the build_script() routine.  (Actually it won't be able to determine what
> >module it belongs to.)
>
> This patch against modutils 2.4.18 fixes it for me.  Unless I hear any
> complaints in the next 24 hours, I will roll modutils 2.4.19 with this
> change on July 31 11:00 UTC.
>
> Segment base is pretty arbitrary for modules, changing it from start of
> text to start of module makes it easier to convert offsets to
> addresses.  It is also what hppa{64} does for SEGREL.
>
> Index: 18.2/obj/obj_ia64.c
> --- 18.2/obj/obj_ia64.c Fri, 01 Mar 2002 11:39:06 +1100 kaos (modutils-2.4/c/0_obj_ia64.c 1.5 644)
> +++ 19.3(w)/obj/obj_ia64.c Tue, 30 Jul 2002 17:47:02 +1000 kaos (modutils-2.4/c/0_obj_ia64.c 1.7 644)
> @@ -911,12 +911,8 @@ arch_apply_relocation(struct obj_file *f
>
>      case R_IA64_SEGREL32LSB :   /* @segrel(sym + add), data4 LSB */
>      case R_IA64_SEGREL64LSB :   /* @segrel(sym + add), data8 LSB */
> -       if (targsec->header.sh_type & SHT_NOBITS)
> -           v = ifile->bss - v;
> -       else if (targsec->header.sh_flags & SHF_EXECINSTR)
> -           v = ifile->text - v;
> -       else
> -           v = ifile->data - v;
> +       /* Only one segment for modules, see segment_base in arch_archdata */
> +       v -= f->baseaddr;
>         if (r_info = R_IA64_SEGREL32LSB)
>             COPY_32LSB(loc, v);
>         else
> @@ -1010,7 +1006,7 @@ arch_archdata (struct obj_file *f, struc
>      ad->unw_start = 0;
>      ad->unw_end = 0;
>      ad->unw_table = 0;
> -    ad->segment_base = f->sections[1]->header.sh_addr;
> +    ad->segment_base = f->baseaddr;
>      for (i = 0; i < f->header.e_shnum; ++i)
>      {
>         sec = f->sections[i];