[Committed][AArch64] Refactor generation of 835769 workaround stubs.

[Marcus Shawcroft <marcus dot shawcroft at arm dot com>]

Hi,

This patch recognises that we only need to perform one scan for the
835769 errata and that this scan can take place before we insert
branch stubs.  The erratum scan code is relocated and adjusted to
create stub entries directly rather than populating an intermediate
representation.  Since stub entries are created immediately we can
drop the adhoc stub size adjustment code and allow the generic stub
sizing code to deal with 835769 stub entries.

This patch restructures the code but does not change the workaround
used to deal with erratum 835769, the exact placement of workaround
stubs in the final image may change slightly after this patch due to
stubs being created in a different order.

Committed

/Marcus

2015-03-24  Marcus Shawcroft  <marcus.shawcroft@arm.com>

	* elfnn-aarch64.c (struct aarch64_erratum_835769_fix) Remove.
	(erratum_835769_scan) Drop fix_table_size_p and fixes_p arguments.
	Delete fixes, fix_table_size and associated code.  Call
	_bfd_aarch64_add_stub_entry_in_group. Rename to...
	(bfd_aarch64_erratum_835769_scan): Define.
	(elfNN_aarch64_size_stubs): Delete erratum_835769_fixes,
	erratum_835769_fix_table_size, i and associated code.  Relocate
	call to _bfd_aarch64_erratum_835769_scan.  Delete adhoc stub size
	correction.  Delete construction of stub entry from
	erratum_835769_fixes array.

diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index d4e6ba4..14b4057 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -1713,17 +1713,6 @@ _aarch64_elf_section_data;
 #define elf_aarch64_section_data(sec) \
   ((_aarch64_elf_section_data *) elf_section_data (sec))
 
-/* A fix-descriptor for erratum 835769.  */
-struct aarch64_erratum_835769_fix
-{
-  bfd *input_bfd;
-  asection *section;
-  bfd_vma offset;
-  uint32_t veneered_insn;
-  char *stub_name;
-  enum elf_aarch64_stub_type stub_type;
-};
-
 /* The size of the thread control block which is defined to be two pointers.  */
 #define TCB_SIZE	(ARCH_SIZE/8)*2
 
@@ -3027,17 +3016,13 @@ _bfd_aarch64_erratum_835769_stub_name (unsigned num_fixes)
    Return TRUE else FALSE on abnormal termination.  */
 
 static bfd_boolean
-erratum_835769_scan (bfd *input_bfd,
-		     struct bfd_link_info *info,
-		     struct aarch64_erratum_835769_fix **fixes_p,
-		     unsigned int *num_fixes_p,
-		     unsigned int *fix_table_size_p)
+_bfd_aarch64_erratum_835769_scan (bfd *input_bfd,
+				  struct bfd_link_info *info,
+				  unsigned int *num_fixes_p)
 {
   asection *section;
   struct elf_aarch64_link_hash_table *htab = elf_aarch64_hash_table (info);
-  struct aarch64_erratum_835769_fix *fixes = *fixes_p;
   unsigned int num_fixes = *num_fixes_p;
-  unsigned int fix_table_size = *fix_table_size_p;
 
   if (htab == NULL)
     return TRUE;
@@ -3086,28 +3071,22 @@ erratum_835769_scan (bfd *input_bfd,
 
 	      if (aarch64_erratum_sequence (insn_1, insn_2))
 		{
+		  struct elf_aarch64_stub_hash_entry *stub_entry;
 		  char *stub_name = _bfd_aarch64_erratum_835769_stub_name (num_fixes);
 		  if (! stub_name)
 		    return FALSE;
 
-		  if (num_fixes == fix_table_size)
-		    {
-		      fix_table_size *= 2;
-		      fixes =
-			(struct aarch64_erratum_835769_fix *)
-			  bfd_realloc (fixes,
-				       sizeof (struct aarch64_erratum_835769_fix)
-					 * fix_table_size);
-		      if (fixes == NULL)
-			return FALSE;
-		    }
+		  stub_entry = _bfd_aarch64_add_stub_entry_in_group (stub_name,
+								     section,
+								     htab);
+		  if (! stub_entry)
+		    return FALSE;
 
-		  fixes[num_fixes].input_bfd = input_bfd;
-		  fixes[num_fixes].section = section;
-		  fixes[num_fixes].offset = i + 4;
-		  fixes[num_fixes].veneered_insn = insn_2;
-		  fixes[num_fixes].stub_name = stub_name;
-		  fixes[num_fixes].stub_type = aarch64_stub_erratum_835769_veneer;
+		  stub_entry->stub_type = aarch64_stub_erratum_835769_veneer;
+		  stub_entry->target_section = section;
+		  stub_entry->target_value = i + 4;
+		  stub_entry->veneered_insn = insn_2;
+		  stub_entry->output_name = stub_name;
 		  num_fixes++;
 		}
 	    }
@@ -3116,9 +3095,6 @@ erratum_835769_scan (bfd *input_bfd,
 	free (contents);
     }
 
-  *fixes_p = fixes;
-  *num_fixes_p = num_fixes;
-  *fix_table_size_p = fix_table_size;
   return TRUE;
 }
 
@@ -3162,23 +3138,9 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
 {
   bfd_size_type stub_group_size;
   bfd_boolean stubs_always_before_branch;
-  bfd_boolean stub_changed = 0;
+  bfd_boolean stub_changed = FALSE;
   struct elf_aarch64_link_hash_table *htab = elf_aarch64_hash_table (info);
-  struct aarch64_erratum_835769_fix *erratum_835769_fixes = NULL;
   unsigned int num_erratum_835769_fixes = 0;
-  unsigned int erratum_835769_fix_table_size = 10;
-  unsigned int i;
-
-  if (htab->fix_erratum_835769)
-    {
-      erratum_835769_fixes
-	= (struct aarch64_erratum_835769_fix *)
-	    bfd_zmalloc
-	      (sizeof (struct aarch64_erratum_835769_fix) *
-					erratum_835769_fix_table_size);
-      if (erratum_835769_fixes == NULL)
-	goto error_ret_free_local;
-    }
 
   /* Propagate mach to stub bfd, because it may not have been
      finalized when we created stub_bfd.  */
@@ -3204,13 +3166,23 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
 
   group_sections (htab, stub_group_size, stubs_always_before_branch);
 
+  if (htab->fix_erratum_835769)
+    {
+      bfd *input_bfd;
+
+      for (input_bfd = info->input_bfds;
+	   input_bfd != NULL; input_bfd = input_bfd->link.next)
+	if (!_bfd_aarch64_erratum_835769_scan (input_bfd, info,
+					       &num_erratum_835769_fixes))
+	  return FALSE;
+
+      stub_changed = TRUE;
+    }
+
   while (1)
     {
       bfd *input_bfd;
-      asection *stub_sec;
-      unsigned prev_num_erratum_835769_fixes = num_erratum_835769_fixes;
 
-      num_erratum_835769_fixes = 0;
       for (input_bfd = info->input_bfds;
 	   input_bfd != NULL; input_bfd = input_bfd->link.next)
 	{
@@ -3463,66 +3435,18 @@ elfNN_aarch64_size_stubs (bfd *output_bfd,
 	      if (elf_section_data (section)->relocs == NULL)
 		free (internal_relocs);
 	    }
-
-	  if (htab->fix_erratum_835769)
-	    {
-	      /* Scan for sequences which might trigger erratum 835769.  */
-	      if (!erratum_835769_scan (input_bfd, info, &erratum_835769_fixes,
-					&num_erratum_835769_fixes,
-					&erratum_835769_fix_table_size))
-		goto error_ret_free_local;
-	    }
 	}
 
-      if (prev_num_erratum_835769_fixes != num_erratum_835769_fixes)
-	stub_changed = TRUE;
-
       if (!stub_changed)
 	break;
 
       _bfd_aarch64_resize_stubs (htab);
 
-      /* Add erratum 835769 veneers to stub section sizes too.  */
-      if (htab->fix_erratum_835769)
-	for (i = 0; i < num_erratum_835769_fixes; i++)
-	  {
-	    stub_sec = _bfd_aarch64_create_or_find_stub_sec
-	      (erratum_835769_fixes[i].section, htab);
-
-	    if (stub_sec == NULL)
-	      goto error_ret_free_local;
-
-	    stub_sec->size += 8;
-	  }
-
       /* Ask the linker to do its stuff.  */
       (*htab->layout_sections_again) ();
       stub_changed = FALSE;
     }
 
-  /* Add stubs for erratum 835769 fixes now.  */
-  if (htab->fix_erratum_835769)
-    {
-      for (i = 0; i < num_erratum_835769_fixes; i++)
-	{
-	  struct elf_aarch64_stub_hash_entry *stub_entry;
-	  char *stub_name = erratum_835769_fixes[i].stub_name;
-	  asection *section = erratum_835769_fixes[i].section;
-
-	  stub_entry = _bfd_aarch64_add_stub_entry_in_group (stub_name,
-							     section,
-							     htab);
-	  if (! stub_entry)
-	    return FALSE;
-
-	  stub_entry->stub_type = erratum_835769_fixes[i].stub_type;
-	  stub_entry->target_section = section;
-	  stub_entry->target_value = erratum_835769_fixes[i].offset;
-	  stub_entry->veneered_insn = erratum_835769_fixes[i].veneered_insn;
-	  stub_entry->output_name = erratum_835769_fixes[i].stub_name;
-	}
-    }
-
   return TRUE;
 
 error_ret_free_local:
-- 
1.9.1