binutils-2.17: --cref broken? Extra warnings and corrupted data

Alan Modra amodra@bigpond.net.au
Wed Jul 19 01:54:00 GMT 2006


On Tue, Jul 18, 2006 at 12:34:09PM +0930, Alan Modra wrote:
> On Mon, Jul 17, 2006 at 03:30:53PM -0700, H. J. Lu wrote:
> > --cref was broken by --as-needed.
> 
> Ah.  My bug then.

This extends the horrible hack of saving the main symbol table to saving
the cref table too.  I'm not proud at all of this hack for --as-needed.
Some day when I have a some time on my hands I'll look at implementing
a two-pass approach to loading --as-needed library syms.

bfd/
	* bfd-in.h (enum notice_asneeded_action): Define.
	* bfd-in2.h: Regenerate.
	* elflink.c (elf_link_add_object_symbols): Call linker "notice"
	function with NULL name for as-needed handling.
ld/
	* ld.h (handle_asneeded_cref): Declare.
	* ldcref.c: Include objalloc.h.
	(old_table, old_count, old_tab, alloc_mark): New variables.
	(tabsize, entsize, refsize, old_symcount): Likewise.
	(add_cref): Use bfd_hash_allocate for refs.
	(handle_asneeded_cref): New function.
	* ldmain.c (notice): Call handle_asneeded_cref for NULL name.

Index: bfd/bfd-in.h
===================================================================
RCS file: /cvs/src/src/bfd/bfd-in.h,v
retrieving revision 1.115
diff -u -p -r1.115 bfd-in.h
--- bfd/bfd-in.h	15 May 2006 19:57:34 -0000	1.115
+++ bfd/bfd-in.h	18 Jul 2006 11:15:14 -0000
@@ -638,6 +638,12 @@ enum dynamic_lib_link_class {
   DYN_NO_NEEDED = 8
 };
 
+enum notice_asneeded_action {
+  notice_as_needed,
+  notice_not_needed,
+  notice_needed
+};
+
 extern bfd_boolean bfd_elf_record_link_assignment
   (bfd *, struct bfd_link_info *, const char *, bfd_boolean,
    bfd_boolean);
Index: bfd/elflink.c
===================================================================
RCS file: /cvs/src/src/bfd/elflink.c,v
retrieving revision 1.224
diff -u -p -r1.224 elflink.c
--- bfd/elflink.c	14 Jul 2006 13:48:06 -0000	1.224
+++ bfd/elflink.c	18 Jul 2006 11:15:39 -0000
@@ -3551,6 +3551,13 @@ elf_link_add_object_symbols (bfd *abfd, 
       if (alloc_mark == NULL)
 	goto error_free_vers;
 
+      /* Make a special call to the linker "notice" function to
+	 tell it that we are about to handle an as-needed lib.  */
+      if (!(*info->callbacks->notice) (info, NULL, abfd, NULL,
+				       notice_as_needed))
+	return FALSE;
+
+
       /* Clone the symbol table and sym hashes.  Remember some
 	 pointers into the symbol table, and dynamic symbol count.  */
       old_hash = (char *) old_tab + tabsize;
@@ -4241,6 +4248,12 @@ elf_link_add_object_symbols (bfd *abfd, 
 	    }
 	}
 
+      /* Make a special call to the linker "notice" function to
+	 tell it that symbols added for crefs may need to be removed.  */
+      if (!(*info->callbacks->notice) (info, NULL, abfd, NULL,
+				       notice_not_needed))
+	return FALSE;
+
       free (old_tab);
       objalloc_free_block ((struct objalloc *) htab->root.table.memory,
 			   alloc_mark);
@@ -4251,6 +4264,9 @@ elf_link_add_object_symbols (bfd *abfd, 
 
   if (old_tab != NULL)
     {
+      if (!(*info->callbacks->notice) (info, NULL, abfd, NULL,
+				       notice_needed))
+	return FALSE;
       free (old_tab);
       old_tab = NULL;
     }
Index: ld/ld.h
===================================================================
RCS file: /cvs/src/src/ld/ld.h,v
retrieving revision 1.31
diff -u -p -r1.31 ld.h
--- ld/ld.h	30 May 2006 16:45:31 -0000	1.31
+++ ld/ld.h	18 Jul 2006 11:16:11 -0000
@@ -288,6 +288,7 @@ extern int parsing_defsym;
 
 extern int yyparse (void);
 extern void add_cref (const char *, bfd *, asection *, bfd_vma);
+extern bfd_boolean handle_asneeded_cref (bfd *, enum notice_asneeded_action);
 extern void output_cref (FILE *);
 extern void check_nocrossrefs (void);
 extern void ld_abort (const char *, int, const char *) ATTRIBUTE_NORETURN;
Index: ld/ldcref.c
===================================================================
RCS file: /cvs/src/src/ld/ldcref.c,v
retrieving revision 1.14
diff -u -p -r1.14 ldcref.c
--- ld/ldcref.c	16 Mar 2006 12:20:16 -0000	1.14
+++ ld/ldcref.c	18 Jul 2006 11:16:12 -0000
@@ -27,6 +27,7 @@ Foundation, Inc., 51 Franklin Street - F
 #include "sysdep.h"
 #include "bfdlink.h"
 #include "libiberty.h"
+#include "objalloc.h"
 
 #include "ld.h"
 #include "ldmain.h"
@@ -101,6 +102,16 @@ static bfd_boolean cref_initialized;
 
 static size_t cref_symcount;
 
+/* Used to take a snapshot of the cref hash table when starting to
+   add syms from an as-needed library.  */
+static struct bfd_hash_entry **old_table;
+static unsigned int old_size;
+static unsigned int old_count;
+static void *old_tab;
+static void *alloc_mark;
+static size_t tabsize, entsize, refsize;
+static size_t old_symcount;
+
 /* Create an entry in a cref hash table.  */
 
 static struct bfd_hash_entry *
@@ -165,7 +176,9 @@ add_cref (const char *name,
 
   if (r == NULL)
     {
-      r = xmalloc (sizeof *r);
+      r = bfd_hash_allocate (&cref_table.root, sizeof *r);
+      if (r == NULL)
+	einfo (_("%X%P: cref alloc failed: %E\n"));
       r->next = h->refs;
       h->refs = r;
       r->abfd = abfd;
@@ -182,6 +195,125 @@ add_cref (const char *name,
     r->def = TRUE;
 }
 
+/* Called before loading an as-needed library to take a snapshot of
+   the cref hash table, and after we have loaded or found that the
+   library was not needed.  */
+
+bfd_boolean
+handle_asneeded_cref (bfd *abfd ATTRIBUTE_UNUSED,
+		      enum notice_asneeded_action act)
+{
+  unsigned int i;
+
+  if (!cref_initialized)
+    return TRUE;
+
+  if (act == notice_as_needed)
+    {
+      char *old_ent, *old_ref;
+
+      for (i = 0; i < cref_table.root.size; i++)
+	{
+	  struct bfd_hash_entry *p;
+	  struct cref_hash_entry *c;
+	  struct cref_ref *r;
+
+	  for (p = cref_table.root.table[i]; p != NULL; p = p->next)
+	    {
+	      entsize += cref_table.root.entsize;
+	      c = (struct cref_hash_entry *) p;
+	      for (r = c->refs; r != NULL; r = r->next)
+		refsize += sizeof (struct cref_hash_entry);
+	    }
+	}
+
+      tabsize = cref_table.root.size * sizeof (struct bfd_hash_entry *);
+      old_tab = xmalloc (tabsize + entsize + refsize);
+
+      alloc_mark = bfd_hash_allocate (&cref_table.root, 1);
+      if (alloc_mark == NULL)
+	return FALSE;
+
+      memcpy (old_tab, cref_table.root.table, tabsize);
+      old_ent = (char *) old_tab + tabsize;
+      old_ref = (char *) old_ent + entsize;
+      old_table = cref_table.root.table;
+      old_size = cref_table.root.size;
+      old_count = cref_table.root.count;
+      old_symcount = cref_symcount;
+
+      for (i = 0; i < cref_table.root.size; i++)
+	{
+	  struct bfd_hash_entry *p;
+	  struct cref_hash_entry *c;
+	  struct cref_ref *r;
+
+	  for (p = cref_table.root.table[i]; p != NULL; p = p->next)
+	    {
+	      memcpy (old_ent, p, cref_table.root.entsize);
+	      old_ent = (char *) old_ent + cref_table.root.entsize;
+	      c = (struct cref_hash_entry *) p;
+	      for (r = c->refs; r != NULL; r = r->next)
+		{
+		  memcpy (old_ref, r, sizeof (struct cref_hash_entry));
+		  old_ref = (char *) old_ref + sizeof (struct cref_hash_entry);
+		}
+	    }
+	}
+      return TRUE;
+    }
+
+  if (act == notice_not_needed)
+    {
+      char *old_ent, *old_ref;
+
+      if (old_tab == NULL)
+	{
+	  /* The only way old_tab can be NULL is if the cref hash table
+	     had not been initialised when notice_as_needed.  */
+	  bfd_hash_table_free (&cref_table.root);
+	  cref_initialized = FALSE;
+	  return TRUE;
+	}
+
+      old_ent = (char *) old_tab + tabsize;
+      old_ref = (char *) old_ent + entsize;
+      cref_table.root.table = old_table;
+      cref_table.root.size = old_size;
+      cref_table.root.count = old_count;
+      memcpy (cref_table.root.table, old_tab, tabsize);
+      cref_symcount = old_symcount;
+
+      for (i = 0; i < cref_table.root.size; i++)
+	{
+	  struct bfd_hash_entry *p;
+	  struct cref_hash_entry *c;
+	  struct cref_ref *r;
+
+	  for (p = cref_table.root.table[i]; p != NULL; p = p->next)
+	    {
+	      memcpy (p, old_ent, cref_table.root.entsize);
+	      old_ent = (char *) old_ent + cref_table.root.entsize;
+	      c = (struct cref_hash_entry *) p;
+	      for (r = c->refs; r != NULL; r = r->next)
+		{
+		  memcpy (r, old_ref, sizeof (struct cref_hash_entry));
+		  old_ref = (char *) old_ref + sizeof (struct cref_hash_entry);
+		}
+	    }
+	}
+
+      objalloc_free_block ((struct objalloc *) cref_table.root.memory,
+			   alloc_mark);
+    }
+  else if (act != notice_needed)
+    return FALSE;
+
+  free (old_tab);
+  old_tab = NULL;
+  return TRUE;
+}
+
 /* Copy the addresses of the hash table entries into an array.  This
    is called via cref_hash_traverse.  We also fill in the demangled
    name.  */
Index: ld/ldmain.c
===================================================================
RCS file: /cvs/src/src/ld/ldmain.c,v
retrieving revision 1.108
diff -u -p -r1.108 ldmain.c
--- ld/ldmain.c	10 Jul 2006 21:40:22 -0000	1.108
+++ ld/ldmain.c	18 Jul 2006 11:16:12 -0000
@@ -1523,6 +1523,13 @@ notice (struct bfd_link_info *info,
 	asection *section,
 	bfd_vma value)
 {
+  if (name == NULL)
+    {
+      if (command_line.cref || nocrossref_list != NULL)
+	return handle_asneeded_cref (abfd, value);
+      return TRUE;
+    }
+
   if (! info->notice_all
       || (info->notice_hash != NULL
 	  && bfd_hash_lookup (info->notice_hash, name, FALSE, FALSE) != NULL))

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre



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