Evaluate __start_* and __stop_* symbol PROVIDE expressions early

Makes these symbols defined before bfd_elf_size_dynamic_sections, to
avoid horrible hacks elsewhere.  The exp_fold_tree undefweak change
is necessary to define undefweak symbols early too.  The comment was
wrong.  PROVIDE in fact defines undefweak symbols, via
bfd_elf_record_link_assignment.

	PR ld/19175
	* ldlang.c (lang_insert_orphan): Evaluate __start_* and __stop_*
	symbol PROVIDE expressions.
	* ldexp.c (exp_fold_tree_1 <etree_provide>): Define undefweak
	references.

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 2cb506a..bef7b26 100644 (file)
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,11 @@
+2015-10-27  Alan Modra  <amodra@gmail.com>
+
+       PR ld/19175
+       * ldlang.c (lang_insert_orphan): Evaluate __start_* and __stop_*
+       symbol PROVIDE expressions.
+       * ldexp.c (exp_fold_tree_1 <etree_provide>): Define undefweak
+       references.
+
 2015-10-22  H.J. Lu  <hongjiu.lu@intel.com>
 
        * configure.ac: Properly check

diff --git a/ld/ldexp.c b/ld/ldexp.c
index 7694f7b..2ec8eb6 100644 (file)
--- a/ld/ldexp.c
+++ b/ld/ldexp.c
@@ -1126,11 +1126,14 @@ exp_fold_tree_1 (etree_type *tree)
              if (h == NULL
                  || !(h->type == bfd_link_hash_new
                       || h->type == bfd_link_hash_undefined
+                      || h->type == bfd_link_hash_undefweak
                       || h->linker_def))
                {
                  /* Do nothing.  The symbol was never referenced, or
-                    was defined in some object file.  Undefined weak
-                    symbols stay undefined.  */
+                    was defined in some object file.  Note that
+                    undefweak symbols are defined by PROVIDE.  This
+                    is to support glibc use of __rela_iplt_start and
+                    similar weak references.  */
                  break;
                }
            }

diff --git a/ld/ldlang.c b/ld/ldlang.c
index 2986981..5c7ea9f 100644 (file)
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -1805,6 +1805,7 @@ lang_insert_orphan (asection *s,
 {
   lang_statement_list_type add;
   const char *ps;
+  lang_assignment_statement_type *start_assign;
   lang_output_section_statement_type *os;
   lang_output_section_statement_type **os_tail;
 
@@ -1827,6 +1828,7 @@ lang_insert_orphan (asection *s,
                                            NULL, NULL, NULL, constraint, 0);
 
   ps = NULL;
+  start_assign = NULL;
   if (config.build_constructors && *os_tail == os)
     {
       /* If the name of the section is representable in C, then create
@@ -1841,9 +1843,10 @@ lang_insert_orphan (asection *s,
          symname = (char *) xmalloc (ps - secname + sizeof "__start_" + 1);
          symname[0] = bfd_get_symbol_leading_char (link_info.output_bfd);
          sprintf (symname + (symname[0] != 0), "__start_%s", secname);
-         lang_add_assignment (exp_provide (symname,
-                                           exp_nameop (NAME, "."),
-                                           FALSE));
+         start_assign
+           = lang_add_assignment (exp_provide (symname,
+                                               exp_nameop (NAME, "."),
+                                               FALSE));
        }
     }
 
@@ -1866,16 +1869,25 @@ lang_insert_orphan (asection *s,
     lang_leave_output_section_statement (NULL, DEFAULT_MEMORY_REGION, NULL,
                                         NULL);
 
-  if (ps != NULL && *ps == '\0')
+  if (start_assign != NULL)
     {
       char *symname;
+      lang_assignment_statement_type *stop_assign;
+      bfd_vma dot;
 
       symname = (char *) xmalloc (ps - secname + sizeof "__stop_" + 1);
       symname[0] = bfd_get_symbol_leading_char (link_info.output_bfd);
       sprintf (symname + (symname[0] != 0), "__stop_%s", secname);
-      lang_add_assignment (exp_provide (symname,
-                                       exp_nameop (NAME, "."),
-                                       FALSE));
+      stop_assign
+       = lang_add_assignment (exp_provide (symname,
+                                           exp_nameop (NAME, "."),
+                                           FALSE));
+      /* Evaluate the expression to define the symbol if referenced,
+        before sizing dynamic sections.  */
+      dot = os->bfd_section->vma;
+      exp_fold_tree (start_assign->exp, os->bfd_section, &dot);
+      dot += s->size;
+      exp_fold_tree (stop_assign->exp, os->bfd_section, &dot);
     }
 
   /* Restore the global list pointer.  */