On Wed, Mar 17, 2021 at 07:46:14PM -0500, Josh Poimboeuf wrote:
> On Wed, Mar 17, 2021 at 03:13:43PM +0100, Peter Zijlstra wrote:
> > On Wed, Mar 17, 2021 at 02:52:23PM +0100, Miroslav Benes wrote:
> >
> > > > + if (!elf_symbol_add(elf, sym, SHN_XINDEX)) {
> > > > + WARN("elf_symbol_add");
> > > > + return NULL;
> > > > + }
> > >
> > > SHN_XINDEX means that the extended section index is used. Above you seem
> > > to use it in the opposite sense too (assigning to shndx when shndx_data
> > > is
> > > NULL). While it makes the code easier to handle, it is a bit confusing
> > > (and maybe I am just confused now). Could you add a comment about that,
> > > please? elf_symbol_add() seems like a good place.
> >
> > Yes, that was a horrible thing to do :/ And you understood it right.
> >
> > Looking at it again, I'm not sure it is actually correct tho; shouldn't
> > elf_create_undef_symbol() also look at gelf_getsymshndx() of symtab ?
> >
> > What toolchain generates these extended sections and how? That is, how
> > do I test this crud..
>
> SHN_XINDEX is basically a special-case extension to original ELF for
> supporting more than 64k sections.
Yeah, I figured it all out again last night; the patch as presented is
hideous but correct(ish). But I've rewritten it and it's all much better
now. Will post later.
