[Bug ld/3169] elfxx-ia64.c doesn't support @ltoff(@fptr(_DYNAMIC#))

[wilson at specifix dot com]

------- Additional Comments From wilson at specifix dot com  2006-09-13 21:01 
-------
Subject: Re:  elfxx-ia64.c doesn't support
        @ltoff(@fptr(_DYNAMIC#))

On Mon, 2006-09-11 at 22:17 +0000, hjl at lucon dot org wrote:
> +                 (*_bfd_error_handler)
> +                   (_("%B: failed to record local dynamic symbol `%s'"),
> +                    h->root.u.def.section->owner, h->root.root.string);

That looks like a good solution for this problem.

> However, it doesn't work for this:

Yes, this is another complication.  The problem here is that _DYNAMIC is
a magic linker variable.  It isn't a variable that came from one of the
object files.  The variable gets created by a call to
_bfd_elf_define_linkage_sym, which puts it in the global symbol hash
table, but not the symbol list for the bar.o file as it didn't come from
bar.o.  However, it is in the bar.o .dynamic section which has a
section->owner which points to bar.o.  So in allocate_fptr, we call
global_sym_index, which then assumes that it must be in bar.o, and
segfaults because it doesn't handle the failure case.

There are a few interesting things about your testcase.  I get the same
error if I use _GLOBAL_OFFSET_TABLE_ instead of _DYNAMIC.  I get no
error if I switch the order of the .o files on the link line.  This is
because section->owner now points to foo.o, and the variable is in
foo.o's symbol table because it was explicitly referenced there.

I think we can handle this with a simple extension of your current
patch.  First we fix global_sym_index to handle the failure case where p
== 0.  We can just return 0 in that case.  Second, we fix allocate_fptr
to check for a 0 return value from global_sym_index, and emit the same
error message as above.

I don't think there is any field in a symbol that says this is a magic
linker created variable.  That would be convenient if it existed.


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=3169

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