[patch] PPC small data symbols.

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[patch] PPC small data symbols.

Paul Brook
VxWorks executables are relocatable. One side-effect of this is that the
linker provided small data base symbols must be section relative, not
absolute.

The attached patch fixes this by passing an option section argument to
_bfd_elf_provide_symbol.

Tested --enable-targets=all on ppc-linux and ppc-vxworks.
Ok?

Paul

2005-06-29  Paul Brook  <[hidden email]>

        * bfd-in.h (_bfd_elf_provide_symbol): Update prototype.
        * bfd-in2.h: Regenerate.
        * elf32-ppc.c (ppc_elf_set_sdata_syms): Make sdata symbols section
        relative.
        * elflink.c (bfd_elf_set_symbol): Add section argument.
        (_bfd_elf_provide_symbol): Ditto.
        (_bfd_elf_provide_section_bound_symbols): Pass NULL section argument.

Index: bfd/bfd-in.h
===================================================================
RCS file: /cvs/src/src/bfd/bfd-in.h,v
retrieving revision 1.102
diff -u -p -r1.102 bfd-in.h
--- bfd/bfd-in.h 4 May 2005 15:53:00 -0000 1.102
+++ bfd/bfd-in.h 29 Jun 2005 00:37:57 -0000
@@ -698,7 +698,7 @@ extern struct bfd_section *_bfd_elf_tls_
   (bfd *, struct bfd_link_info *);
 
 extern void _bfd_elf_provide_symbol
-  (struct bfd_link_info *, const char *, bfd_vma);
+  (struct bfd_link_info *, const char *, bfd_vma, struct bfd_section *);
 
 extern void _bfd_elf_provide_section_bound_symbols
   (struct bfd_link_info *, struct bfd_section *sec, const char *, const char *);
Index: bfd/bfd-in2.h
===================================================================
RCS file: /cvs/src/src/bfd/bfd-in2.h,v
retrieving revision 1.346
diff -u -p -r1.346 bfd-in2.h
--- bfd/bfd-in2.h 17 Jun 2005 08:03:46 -0000 1.346
+++ bfd/bfd-in2.h 29 Jun 2005 00:37:57 -0000
@@ -705,7 +705,7 @@ extern struct bfd_section *_bfd_elf_tls_
   (bfd *, struct bfd_link_info *);
 
 extern void _bfd_elf_provide_symbol
-  (struct bfd_link_info *, const char *, bfd_vma);
+  (struct bfd_link_info *, const char *, bfd_vma, struct bfd_section *);
 
 extern void _bfd_elf_provide_section_bound_symbols
   (struct bfd_link_info *, struct bfd_section *sec, const char *, const char *);
Index: bfd/elf32-ppc.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-ppc.c,v
retrieving revision 1.164
diff -u -p -r1.164 elf32-ppc.c
--- bfd/elf32-ppc.c 20 Jun 2005 18:12:07 -0000 1.164
+++ bfd/elf32-ppc.c 29 Jun 2005 00:37:57 -0000
@@ -5108,24 +5108,38 @@ ppc_elf_set_sdata_syms (bfd *obfd, struc
       if (s == NULL)
  s = bfd_get_section_by_name (obfd, lsect->bss_name);
 
-      val = 0;
-      if (s != NULL)
- val = s->vma + 32768;
-      lsect->sym_val = val;
+      if (s)
+ {
+  /* VxWorks executables are relocatable, so the sdata base symbols
+     must be section-relative.  If the section is zero sized leave
+     them as absolute symbols to avoid creationg an unused
+     output section.  */
+  val = 32768;
+  lsect->sym_val = val + s->vma;
+  if (s->size == 0)
+    {
+      val += s->vma;
+      s = NULL;
+    }
+ }
+      else
+ {
+  val = 0;
+  lsect->sym_val = 0;
+ }
 
-      _bfd_elf_provide_symbol (info, lsect->sym_name, val);
+      _bfd_elf_provide_symbol (info, lsect->sym_name, val, s);
     }
 
   s = bfd_get_section_by_name (obfd, ".sbss");
-  val = 0;
+  _bfd_elf_provide_symbol (info, "__sbss_start", 0, NULL);
+  _bfd_elf_provide_symbol (info, "___sbss_start", 0, NULL);
   if (s != NULL)
-    val = s->vma;
-  _bfd_elf_provide_symbol (info, "__sbss_start", val);
-  _bfd_elf_provide_symbol (info, "___sbss_start", val);
-  if (s != NULL)
-    val += s->size;
-  _bfd_elf_provide_symbol (info, "__sbss_end", val);
-  _bfd_elf_provide_symbol (info, "___sbss_end", val);
+    val = s->size;
+  else
+    val = 0;
+  _bfd_elf_provide_symbol (info, "__sbss_end", val, s);
+  _bfd_elf_provide_symbol (info, "___sbss_end", val, s);
   return TRUE;
 }
 
Index: bfd/elflink.c
===================================================================
RCS file: /cvs/src/src/bfd/elflink.c,v
retrieving revision 1.168
diff -u -p -r1.168 elflink.c
--- bfd/elflink.c 14 Jun 2005 19:25:45 -0000 1.168
+++ bfd/elflink.c 29 Jun 2005 00:37:58 -0000
@@ -9792,10 +9792,11 @@ _bfd_elf_section_already_linked (bfd *ab
 }
 
 static void
-bfd_elf_set_symbol (struct elf_link_hash_entry *h, bfd_vma val)
+bfd_elf_set_symbol (struct elf_link_hash_entry *h, bfd_vma val,
+    struct bfd_section *s)
 {
   h->root.type = bfd_link_hash_defined;
-  h->root.u.def.section = bfd_abs_section_ptr;
+  h->root.u.def.section = s ? s : bfd_abs_section_ptr;
   h->root.u.def.value = val;
   h->def_regular = 1;
   h->type = STT_OBJECT;
@@ -9803,11 +9804,12 @@ bfd_elf_set_symbol (struct elf_link_hash
   h->forced_local = 1;
 }
 
-/* Set NAME to VAL if the symbol exists and is undefined.  */
+/* Set NAME to VAL if the symbol exists and is undefined.  If val is NULL
+   it is an absolute symbol, otherwise it is relative to that section.  */
 
 void
 _bfd_elf_provide_symbol (struct bfd_link_info *info, const char *name,
- bfd_vma val)
+ bfd_vma val, struct bfd_section *s)
 {
   struct elf_link_hash_entry *h;
 
@@ -9815,7 +9817,7 @@ _bfd_elf_provide_symbol (struct bfd_link
     FALSE);
   if (h != NULL && (h->root.type == bfd_link_hash_undefined
     || h->root.type == bfd_link_hash_undefweak))
-    bfd_elf_set_symbol (h, val);
+    bfd_elf_set_symbol (h, val, s);
 }
 
 /* Set START and END to boundaries of SEC if they exist and are
@@ -9868,8 +9870,8 @@ _bfd_elf_provide_section_bound_symbols (
     }
 
   if (do_start)
-    bfd_elf_set_symbol (hs, start_val);
+    bfd_elf_set_symbol (hs, start_val, NULL);
 
   if (do_end)
-    bfd_elf_set_symbol (he, end_val);
+    bfd_elf_set_symbol (he, end_val, NULL);
 }
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Re: [patch] PPC small data symbols.

Alan Modra
On Wed, Jun 29, 2005 at 02:22:40AM +0100, Paul Brook wrote:
> * bfd-in.h (_bfd_elf_provide_symbol): Update prototype.
> * bfd-in2.h: Regenerate.
> * elf32-ppc.c (ppc_elf_set_sdata_syms): Make sdata symbols section
> relative.
> * elflink.c (bfd_elf_set_symbol): Add section argument.
> (_bfd_elf_provide_symbol): Ditto.
> (_bfd_elf_provide_section_bound_symbols): Pass NULL section argument.

OK.

--
Alan Modra
IBM OzLabs - Linux Technology Centre
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Re: [patch] PPC small data symbols.

Alan Modra
In reply to this post by Paul Brook
On Wed, Jun 29, 2005 at 02:22:40AM +0100, Paul Brook wrote:
> * elf32-ppc.c (ppc_elf_set_sdata_syms): Make sdata symbols section
> relative.

This slipped past my review.

        * elf32-ppc.c (ppc_elf_set_sdata_syms): Correct __sbss_start value.

Index: bfd/elf32-ppc.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-ppc.c,v
retrieving revision 1.171
diff -u -p -r1.171 elf32-ppc.c
--- bfd/elf32-ppc.c 8 Jul 2005 06:19:59 -0000 1.171
+++ bfd/elf32-ppc.c 12 Jul 2005 09:40:43 -0000
@@ -5307,12 +5311,11 @@ ppc_elf_set_sdata_syms (bfd *obfd, struc
     }
 
   s = bfd_get_section_by_name (obfd, ".sbss");
-  _bfd_elf_provide_symbol (info, "__sbss_start", 0, NULL);
-  _bfd_elf_provide_symbol (info, "___sbss_start", 0, NULL);
+  val = 0;
+  _bfd_elf_provide_symbol (info, "__sbss_start", val, s);
+  _bfd_elf_provide_symbol (info, "___sbss_start", val, s);
   if (s != NULL)
     val = s->size;
-  else
-    val = 0;
   _bfd_elf_provide_symbol (info, "__sbss_end", val, s);
   _bfd_elf_provide_symbol (info, "___sbss_end", val, s);
   return TRUE;

--
Alan Modra
IBM OzLabs - Linux Technology Centre