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PATCH: ELF linker is broken
On Mon, Jan 31, 2005 at 01:22:03PM -0800, H. J. Lu wrote:
> On Mon, Jan 31, 2005 at 05:43:08PM +1030, Alan Modra wrote:
> > On Mon, Jan 31, 2005 at 10:32:27AM +1030, Alan Modra wrote:
> > > On Sun, Jan 30, 2005 at 11:22:49AM -0800, H. J. Lu wrote:
> > > > /usr/lib/crt1.o:(.dynamic+0x0): multiple definition of `_DYNAMIC'
> > > [snip]
> > > > The 2005-01-24 binutils is OK. It may have something to do with
> > > >
> > > > http://sources.redhat.com/ml/binutils/2005-01/msg00405.html
> > >
> > > Possible, I suppose. An as-needed shared lib will define syms whether
> > > or not the lib is actually linked. It will be linked if any symbol it
> > > defines satisfies an undefined reference, and conversely it isn't linked
> > > then there are no references to its symbols. That should make it safe
> > > to leave its symbols in the symbol table, so long as we properly treat
> > > them in _bfd_elf_merge_symbol. If there is a problem, it's likely to be
> > > in _bfd_elf_merge_symbol.
> >
> > I'm testing the following on powerpc and x86 to ensure I haven't made
> > any silly mistakes. It's a big hammer approach but cleaner than what we
> > had before, I think. Rather than tweaking _bfd_elf_merge_symbol and
> > other places to specially handle symbols defined in unused --as-needed
> > libs, I've munged all such symbols back to their new state. Hopefully
> > this won't break too many back-end elf_link_hash_traverse functions..
> >
> > Would you please test this on ia64? I don't have access to ia64
> > hardware, so testing this isn't so easy.
>
> I am enclosing a testcase here. I saw the same problem on ia32, ia64
> and x86_64:
>
This patch works for me.
H.J.
----
2005-01-31 H.J. Lu <hongjiu.lu@intel.com>
* elflink.c (_bfd_elf_link_create_dynamic_sections): Discard
previous "_DYNAMIC" before creating the new one.
--- bfd/elflink.c.dynamic 2005-01-31 12:19:55.000000000 -0800
+++ bfd/elflink.c 2005-01-31 13:59:00.463355292 -0800
@@ -216,7 +216,19 @@ _bfd_elf_link_create_dynamic_sections (b
linker script, but we only want to define it if we are, in fact,
creating a .dynamic section. We don't want to define it if there
is no .dynamic section, since on some ELF platforms the start up
- code examines it to decide how to initialize the process. */
+ code examines it to decide how to initialize the process.
+
+ _DYNAMIC is a special symbol. We used to create it before reading
+ symbol tables from shared libraries. But now it is delayed. We
+ discard any previous definition from shared library before we
+ create this one. */
+ h = elf_link_hash_lookup (elf_hash_table (info), "_DYNAMIC", FALSE,
+ FALSE, FALSE);
+ if (h)
+ {
+ h->root.type = bfd_link_hash_undefined;
+ h->root.u.undef.abfd = abfd;
+ }
bh = NULL;
if (! (_bfd_generic_link_add_one_symbol
(info, abfd, "_DYNAMIC", BSF_GLOBAL, s, 0, NULL, FALSE,