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Re: PATCH: ld/2218: Weak undefined symbol doesn't work properly with PIE
On Mon, Feb 20, 2006 at 12:09:10PM -0800, H. J. Lu wrote:
> On Tue, Feb 21, 2006 at 11:24:24AM +1030, Alan Modra wrote:
> > On Sun, Feb 19, 2006 at 07:31:58PM -0800, H. J. Lu wrote:
> > > On Tue, Feb 21, 2006 at 10:35:47AM +1030, Alan Modra wrote:
> > > > On Sun, Feb 19, 2006 at 06:10:01PM -0800, H. J. Lu wrote:
> > > > > Do you have a patch for ia64?
> > > >
> > > > Nope. I was leaving that to you.
> > >
> > > I don't understand why we should do the same thing over and over in
> > > so many backends. A target hook should reduce the code duplication if
> > > a few targets want to do it differently.
> >
> > Show me the code. I will not approve a target hook that does worse than
> > a backend implementation. ie. that makes symbols dynamic unnecessarily.
> >
>
> I am checking this patch to test weak undefined data. I will
> fix ia64 backend.
>
>
Due to the complexity of ia64 backend, it is better to handle weak
undefined symbol in _bfd_elf_fix_symbol_flags for ia64.
H.J.
----
2006-02-20 H.J. Lu <hongjiu.lu@intel.com>
PR ld/2218
* elf-bfd.h (elf_backend_data): Add elf_backend_fixup_symbol.
(_bfd_elf_link_hash_fixup_symbol): New.
* elflink.c (_bfd_elf_link_hash_fixup_symbol): New.
(_bfd_elf_fix_symbol_flags): Call elf_backend_fixup_symbol if
it isn't NULL.
* elfxx-ia64.c (elf_backend_fixup_symbol): Defined.
* elfxx-target.h (elf_backend_fixup_symbol): New.
(elfNN_bed): Initialize elf_backend_fixup_symbol.
--- bfd/elf-bfd.h.ia64 2006-01-20 08:53:55.000000000 -0800
+++ bfd/elf-bfd.h 2006-02-20 18:06:49.000000000 -0800
@@ -883,6 +883,11 @@ struct elf_backend_data
void (*elf_backend_hide_symbol)
(struct bfd_link_info *, struct elf_link_hash_entry *, bfd_boolean);
+ /* A function to do additional symbol fixup, called by
+ _bfd_elf_fix_symbol_flags. */
+ bfd_boolean (*elf_backend_fixup_symbol)
+ (struct bfd_link_info *, struct elf_link_hash_entry *);
+
/* Merge the backend specific symbol attribute. */
void (*elf_backend_merge_symbol_attribute)
(struct elf_link_hash_entry *, const Elf_Internal_Sym *, bfd_boolean,
@@ -1476,6 +1481,8 @@ extern void _bfd_elf_link_hash_copy_indi
struct elf_link_hash_entry *);
extern void _bfd_elf_link_hash_hide_symbol
(struct bfd_link_info *, struct elf_link_hash_entry *, bfd_boolean);
+extern bfd_boolean _bfd_elf_link_hash_fixup_symbol
+ (struct bfd_link_info *, struct elf_link_hash_entry *);
extern bfd_boolean _bfd_elf_link_hash_table_init
(struct elf_link_hash_table *, bfd *,
struct bfd_hash_entry *(*)
--- bfd/elflink.c.ia64 2006-02-20 10:40:52.000000000 -0800
+++ bfd/elflink.c 2006-02-20 18:07:31.000000000 -0800
@@ -2187,6 +2187,20 @@ _bfd_elf_link_output_relocs (bfd *output
return TRUE;
}
+/* Make weak undefined symbols in PIE dynamic. */
+
+bfd_boolean
+_bfd_elf_link_hash_fixup_symbol (struct bfd_link_info *info,
+ struct elf_link_hash_entry *h)
+{
+ if (info->pie
+ && h->dynindx == -1
+ && h->root.type == bfd_link_hash_undefweak)
+ return bfd_elf_link_record_dynamic_symbol (info, h);
+
+ return TRUE;
+}
+
/* Fix up the flags for a symbol. This handles various cases which
can only be fixed after all the input files are seen. This is
currently called by both adjust_dynamic_symbol and
@@ -2197,6 +2211,8 @@ bfd_boolean
_bfd_elf_fix_symbol_flags (struct elf_link_hash_entry *h,
struct elf_info_failed *eif)
{
+ const struct elf_backend_data *bed = NULL;
+
/* If this symbol was mentioned in a non-ELF file, try to set
DEF_REGULAR and REF_REGULAR correctly. This is the only way to
permit a non-ELF file to correctly refer to a symbol defined in
@@ -2255,6 +2271,15 @@ _bfd_elf_fix_symbol_flags (struct elf_li
h->def_regular = 1;
}
+ /* Backend specific symbol fixup. */
+ if (elf_hash_table (eif->info)->dynobj)
+ {
+ bed = get_elf_backend_data (elf_hash_table (eif->info)->dynobj);
+ if (bed->elf_backend_fixup_symbol
+ && !(*bed->elf_backend_fixup_symbol) (eif->info, h))
+ return FALSE;
+ }
+
/* If this is a final link, and the symbol was defined as a common
symbol in a regular object file, and there was no definition in
any dynamic object, then the linker will have allocated space for
@@ -2280,11 +2305,8 @@ _bfd_elf_fix_symbol_flags (struct elf_li
|| ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
&& h->def_regular)
{
- const struct elf_backend_data *bed;
bfd_boolean force_local;
- bed = get_elf_backend_data (elf_hash_table (eif->info)->dynobj);
-
force_local = (ELF_ST_VISIBILITY (h->other) == STV_INTERNAL
|| ELF_ST_VISIBILITY (h->other) == STV_HIDDEN);
(*bed->elf_backend_hide_symbol) (eif->info, h, force_local);
@@ -2323,12 +2345,8 @@ _bfd_elf_fix_symbol_flags (struct elf_li
if (weakdef->def_regular)
h->u.weakdef = NULL;
else
- {
- const struct elf_backend_data *bed;
-
- bed = get_elf_backend_data (elf_hash_table (eif->info)->dynobj);
- (*bed->elf_backend_copy_indirect_symbol) (eif->info, weakdef, h);
- }
+ (*bed->elf_backend_copy_indirect_symbol) (eif->info, weakdef,
+ h);
}
return TRUE;
--- bfd/elfxx-ia64.c.ia64 2006-02-06 13:58:53.000000000 -0800
+++ bfd/elfxx-ia64.c 2006-02-20 18:09:25.000000000 -0800
@@ -5305,6 +5305,7 @@ elfNN_hpux_backend_symbol_processing (bf
#define elf_backend_want_dynbss 0
#define elf_backend_copy_indirect_symbol elfNN_ia64_hash_copy_indirect
#define elf_backend_hide_symbol elfNN_ia64_hash_hide_symbol
+#define elf_backend_fixup_symbol _bfd_elf_link_hash_fixup_symbol
#define elf_backend_reloc_type_class elfNN_ia64_reloc_type_class
#define elf_backend_rela_normal 1
#define elf_backend_special_sections elfNN_ia64_special_sections
--- bfd/elfxx-target.h.ia64 2006-01-20 08:53:57.000000000 -0800
+++ bfd/elfxx-target.h 2006-02-20 17:58:20.000000000 -0800
@@ -420,6 +420,9 @@
#ifndef elf_backend_hide_symbol
#define elf_backend_hide_symbol _bfd_elf_link_hash_hide_symbol
#endif
+#ifndef elf_backend_fixup_symbol
+#define elf_backend_fixup_symbol NULL
+#endif
#ifndef elf_backend_merge_symbol_attribute
#define elf_backend_merge_symbol_attribute NULL
#endif
@@ -598,6 +601,7 @@ static const struct elf_backend_data elf
elf_backend_output_arch_syms,
elf_backend_copy_indirect_symbol,
elf_backend_hide_symbol,
+ elf_backend_fixup_symbol,
elf_backend_merge_symbol_attribute,
elf_backend_ignore_undef_symbol,
elf_backend_emit_relocs,