Yet another unnecessary powerpc section
Alan Modra
amodra@bigpond.net.au
Tue Mar 22 08:16:00 GMT 2005
On Tue, Mar 22, 2005 at 12:30:03AM +1030, Alan Modra wrote:
> * scripttempl/elf.sc (SBSS): Don't provide sbss start and end syms.
Sigh. It appears my search through source wasn't comprehensive enough.
libgloss uses __sbss_start and __sbss_end.
* elf32-ppc.c (set_linker_sym): New function, extracted from..
(ppc_elf_set_sdata_syms): ..here. Expand comment. Set .sbss
start and end syms.
Index: bfd/elf32-ppc.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-ppc.c,v
retrieving revision 1.144
diff -u -p -r1.144 elf32-ppc.c
--- bfd/elf32-ppc.c 21 Mar 2005 13:56:47 -0000 1.144
+++ bfd/elf32-ppc.c 22 Mar 2005 03:06:16 -0000
@@ -4570,22 +4570,46 @@ ppc_elf_relax_section (bfd *abfd,
return FALSE;
}
-/* Set _SDA_BASE_ and _SDA2_BASE. */
+/* Set SYM_NAME to VAL if the symbol exists and is undefined. */
+
+static void
+set_linker_sym (struct ppc_elf_link_hash_table *htab,
+ const char *sym_name,
+ bfd_vma val)
+{
+ struct elf_link_hash_entry *h;
+ h = elf_link_hash_lookup (&htab->elf, sym_name, FALSE, FALSE, FALSE);
+ if (h != NULL && h->root.type == bfd_link_hash_undefined)
+ {
+ h->root.type = bfd_link_hash_defined;
+ h->root.u.def.section = bfd_abs_section_ptr;
+ h->root.u.def.value = val;
+ h->def_regular = 1;
+ h->type = STT_OBJECT;
+ h->other = STV_HIDDEN;
+ }
+}
+
+/* Set _SDA_BASE_, _SDA2_BASE, and sbss start and end syms. They are
+ set here rather than via PROVIDE in the default linker script,
+ because using PROVIDE inside an output section statement results in
+ unnecessary output sections. Using PROVIDE outside an output section
+ statement runs the risk of section alignment affecting where the
+ section starts. */
bfd_boolean
ppc_elf_set_sdata_syms (bfd *obfd, struct bfd_link_info *info)
{
struct ppc_elf_link_hash_table *htab;
unsigned i;
+ asection *s;
+ bfd_vma val;
htab = ppc_elf_hash_table (info);
for (i = 0; i < 2; i++)
{
elf_linker_section_t *lsect = &htab->sdata[i];
- asection *s;
- bfd_vma val;
- struct elf_link_hash_entry *h;
s = lsect->section;
if (s != NULL)
@@ -4600,18 +4624,19 @@ ppc_elf_set_sdata_syms (bfd *obfd, struc
val = s->vma + 32768;
lsect->sym_val = val;
- h = elf_link_hash_lookup (&htab->elf, lsect->sym_name,
- FALSE, FALSE, FALSE);
- if (h != NULL && h->root.type == bfd_link_hash_undefined)
- {
- h->root.type = bfd_link_hash_defined;
- h->root.u.def.section = bfd_abs_section_ptr;
- h->root.u.def.value = val;
- h->def_regular = 1;
- h->type = STT_OBJECT;
- h->other = STV_HIDDEN;
- }
+ set_linker_sym (htab, lsect->sym_name, val);
}
+
+ s = bfd_get_section_by_name (obfd, ".sbss");
+ val = 0;
+ if (s != NULL)
+ val = s->vma;
+ set_linker_sym (htab, "__sbss_start", val);
+ set_linker_sym (htab, "___sbss_start", val);
+ if (s != NULL)
+ val += s->size;
+ set_linker_sym (htab, "__sbss_end", val);
+ set_linker_sym (htab, "___sbss_end", val);
return TRUE;
}
--
Alan Modra
IBM OzLabs - Linux Technology Centre
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