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Re: _bfd_dwarf2_find_nearest_line returns wrong filename


On Sun, Jan 19, 2003 at 06:00:21PM +0100, Andreas Schwab wrote:
> Daniel Jacobowitz <drow@mvista.com> writes:
> 
> |> On Fri, Jan 03, 2003 at 03:39:40PM +0100, Andreas Schwab wrote:
> |> > Daniel Jacobowitz <drow@mvista.com> writes:
> |> > 
> |> > |> No regressions, but some pertinent facts:
> |> > |> 
> |> > |>  - Examine the ld.log with this patch applied.  Grep for BFD.  You'll
> |> > |>    find several assertion failures indicating that the DWARF-2 data
> |> > |>    is incorrect.  It's kind of sad that the testsuite doesn't notice any
> |> > |>    of these.
> |> > 
> |> > I have now tried it on ia64, and it is getting worse.  They are using
> |> > R_IA64_SECREL32LS relocations in .debug_info, which is causing
> |> > bfd_perform_relocation to return bfd_reloc_outofrange, and
> |> > bfd_generic_get_relocated_section_contents is aborting on that.
> |> 
> |> We needed to save and restore outputs in order to get the right answers
> |> on i386 in some cases.  We also needed some other fixes to ia64 - I
> |> missed it when I swept the hash table create functions to make them use
> |> bfd_malloc, I guess - and to weaken an abort in elfNN_ia64_reloc.  But
> |> now it works.
> 
> This does not seem to work in the linker, it doesn't emit any filename
> prefixes any more.  This also causes testsuite failures, the ld-elfvsb
> tests depend on the filename part of the error messages.

I had the right idea, but I wasn't thorough enough implementing it.  In
addition to dummying the output offsets, we also have to dummy the
output sections.  Otherwise .debug_info thinks that a function starts
up past 0x08400000, and the rest of the linker thinks that it starts at
0x18.

Andreas, thanks for your continued patience.  Would you mind testing
this version?

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer

2003-02-04  Andreas Schwab  <schwab@suse.de>
	    Daniel Jacobowitz  <drow@mvista.com>

	* simple.c (bfd_simple_get_relocated_section_contents): Add
	parameter symbol_table.  Optionally use it instead of the symbol
	table from the bfd.  Save and restore output offsets and output
	sections  around bfd_get_relocated_section_contents.  Fix a memory
	leak.
	(simple_save_output_info, simple_restore_output_info): New
	functions.
	* bfd-in2.h: Regenerate.
	* dwarf2.c (read_abbrevs): Use
	bfd_simple_get_relocated_section_contents instead of
	bfd_get_section_contents.
	(decode_line_info): Likewise.
	(_bfd_dwarf2_find_nearest_line): Likewise.  Don't call
	find_rela_addend.
	(find_rela_addend): Remove.
	* elfxx-ia64.c (elfNN_ia64_reloc): Weaken sanity check for
	debugging sections.
	(elfNN_ia64_hash_table_create): Create the hash table with malloc,
	not bfd_zalloc.

Index: bfd/dwarf2.c
===================================================================
RCS file: /big/fsf/rsync/src-cvs/src/bfd/dwarf2.c,v
retrieving revision 1.42
diff -u -p -r1.42 dwarf2.c
--- bfd/dwarf2.c	12 Dec 2002 10:26:01 -0000	1.42
+++ bfd/dwarf2.c	16 Jan 2003 20:52:45 -0000
@@ -245,8 +245,6 @@ static bfd_boolean lookup_address_in_lin
 static bfd_boolean lookup_address_in_function_table
   PARAMS ((struct funcinfo *, bfd_vma, struct funcinfo **, const char **));
 static bfd_boolean scan_unit_for_functions PARAMS ((struct comp_unit *));
-static bfd_vma find_rela_addend
-  PARAMS ((bfd *, asection *, bfd_size_type, asymbol**));
 static struct comp_unit *parse_comp_unit
   PARAMS ((bfd *, struct dwarf2_debug *, bfd_vma, unsigned int));
 static bfd_boolean comp_unit_contains_address
@@ -546,13 +544,11 @@ read_abbrevs (abfd, offset, stash)
 	}
 
       stash->dwarf_abbrev_size = msec->_raw_size;
-      stash->dwarf_abbrev_buffer = (char*) bfd_alloc (abfd, msec->_raw_size);
+      stash->dwarf_abbrev_buffer
+	= bfd_simple_get_relocated_section_contents (abfd, msec, NULL,
+						     stash->syms);
       if (! stash->dwarf_abbrev_buffer)
 	  return 0;
-
-      if (! bfd_get_section_contents (abfd, msec, stash->dwarf_abbrev_buffer,
-				      (bfd_vma) 0, msec->_raw_size))
-	return 0;
     }
 
   if (offset >= stash->dwarf_abbrev_size)
@@ -1019,21 +1015,15 @@ decode_line_info (unit, stash)
 	}
 
       stash->dwarf_line_size = msec->_raw_size;
-      stash->dwarf_line_buffer = (char *) bfd_alloc (abfd, msec->_raw_size);
+      stash->dwarf_line_buffer
+	= bfd_simple_get_relocated_section_contents (abfd, msec, NULL,
+						     stash->syms);
       if (! stash->dwarf_line_buffer)
 	return 0;
-
-      if (! bfd_get_section_contents (abfd, msec, stash->dwarf_line_buffer,
-				      (bfd_vma) 0, msec->_raw_size))
-	return 0;
-
-      /* FIXME: We ought to apply the relocs against this section before
-	 we process it...  */
     }
 
-  /* Since we are using un-relocated data, it is possible to get a bad value
-     for the line_offset.  Validate it here so that we won't get a segfault
-     below.  */
+  /* It is possible to get a bad value for the line_offset.  Validate
+     it here so that we won't get a segfault below.  */
   if (unit->line_offset >= stash->dwarf_line_size)
     {
       (*_bfd_error_handler) (_("Dwarf Error: Line offset (%lu) greater than or equal to .debug_line size (%lu)."),
@@ -1521,60 +1511,6 @@ scan_unit_for_functions (unit)
   return TRUE;
 }
 
-/* Look for a RELA relocation to be applied on OFFSET of section SEC,
-   and return the addend if such a relocation is found.  Since this is
-   only used to find relocations referring to the .debug_abbrev
-   section, we make sure the relocation refers to this section, but
-   this is not strictly necessary, and it can probably be safely
-   removed if needed.  However, it is important to note that this
-   function only returns the addend, it doesn't serve the purpose of
-   applying a generic relocation.
-
-   If no suitable relocation is found, or if it is not a real RELA
-   relocation, this function returns 0.  */
-
-static bfd_vma
-find_rela_addend (abfd, sec, offset, syms)
-     bfd* abfd;
-     asection* sec;
-     bfd_size_type offset;
-     asymbol** syms;
-{
-  long reloc_size = bfd_get_reloc_upper_bound (abfd, sec);
-  arelent **relocs = NULL;
-  long reloc_count, relc;
-
-  if (reloc_size <= 0)
-    return 0;
-
-  relocs = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
-  if (relocs == NULL)
-    return 0;
-
-  reloc_count = bfd_canonicalize_reloc (abfd, sec, relocs, syms);
-
-  if (reloc_count <= 0)
-    {
-      free (relocs);
-      return 0;
-    }
-
-  for (relc = 0; relc < reloc_count; relc++)
-    if (relocs[relc]->address == offset
-	&& (*relocs[relc]->sym_ptr_ptr)->flags & BSF_SECTION_SYM
-	&& strcmp ((*relocs[relc]->sym_ptr_ptr)->name,
-		   ".debug_abbrev") == 0)
-      {
-	bfd_vma addend = (relocs[relc]->howto->partial_inplace
-			  ? 0 : relocs[relc]->addend);
-	free (relocs);
-	return addend;
-      }
-
-  free (relocs);
-  return 0;
-}
-
 /* Parse a DWARF2 compilation unit starting at INFO_PTR.  This
    includes the compilation unit header that proceeds the DIE's, but
    does not include the length field that preceeds each compilation
@@ -1602,7 +1538,6 @@ parse_comp_unit (abfd, stash, unit_lengt
   char *info_ptr = stash->info_ptr;
   char *end_ptr = info_ptr + unit_length;
   bfd_size_type amt;
-  bfd_size_type off;
 
   version = read_2_bytes (abfd, info_ptr);
   info_ptr += 2;
@@ -1611,12 +1546,6 @@ parse_comp_unit (abfd, stash, unit_lengt
     abbrev_offset = read_4_bytes (abfd, info_ptr);
   else
     abbrev_offset = read_8_bytes (abfd, info_ptr);
-  /* The abbrev offset is generally a relocation pointing to
-     .debug_abbrev+offset.  On RELA targets, we have to find the
-     relocation and extract the addend to obtain the actual
-     abbrev_offset, so do it here.  */
-  off = info_ptr - stash->sec_info_ptr;
-  abbrev_offset += find_rela_addend (abfd, stash->sec, off, stash->syms);
   info_ptr += offset_size;
   addr_size = read_1_byte (abfd, info_ptr);
   info_ptr += 1;
@@ -1939,8 +1868,8 @@ _bfd_dwarf2_find_nearest_line (abfd, sec
 
 	  start = stash->info_ptr_end - stash->info_ptr;
 
-	  if (! bfd_get_section_contents (abfd, msec, stash->info_ptr + start,
-					  (bfd_vma) 0, size))
+	  if ((bfd_simple_get_relocated_section_contents
+	       (abfd, msec, stash->info_ptr + start, symbols)) == NULL)
 	    continue;
 
 	  stash->info_ptr_end = stash->info_ptr + start + size;
@@ -1953,21 +1882,6 @@ _bfd_dwarf2_find_nearest_line (abfd, sec
       stash->syms = symbols;
     }
 
-  /* FIXME: There is a problem with the contents of the
-     .debug_info section.  The 'low' and 'high' addresses of the
-     comp_units are computed by relocs against symbols in the
-     .text segment.  We need these addresses in order to determine
-     the nearest line number, and so we have to resolve the
-     relocs.  There is a similar problem when the .debug_line
-     section is processed as well (e.g., there may be relocs
-     against the operand of the DW_LNE_set_address operator).
-
-     Unfortunately getting hold of the reloc information is hard...
-
-     For now, this means that disassembling object files (as
-     opposed to fully executables) does not always work as well as
-     we would like.  */
-
   /* A null info_ptr indicates that there is no dwarf2 info
      (or that an error occured while setting up the stash).  */
   if (! stash->info_ptr)
@@ -2034,10 +1948,10 @@ _bfd_dwarf2_find_nearest_line (abfd, sec
 		{
 		  if (comp_unit_contains_address (each, addr))
 		    return comp_unit_find_nearest_line (each, addr,
-						       filename_ptr,
-						       functionname_ptr,
-						       linenumber_ptr,
-						       stash);
+							filename_ptr,
+							functionname_ptr,
+							linenumber_ptr,
+							stash);
 		}
 	      else
 		{
Index: bfd/elfxx-ia64.c
===================================================================
RCS file: /big/fsf/rsync/src-cvs/src/bfd/elfxx-ia64.c,v
retrieving revision 1.66
diff -u -p -r1.66 elfxx-ia64.c
--- bfd/elfxx-ia64.c	17 Jan 2003 23:27:55 -0000	1.66
+++ bfd/elfxx-ia64.c	4 Feb 2003 15:31:06 -0000
@@ -346,6 +346,10 @@ elfNN_ia64_reloc (abfd, reloc, sym, data
       reloc->address += input_section->output_offset;
       return bfd_reloc_ok;
     }
+
+  if (input_section->flags & SEC_DEBUGGING)
+    return bfd_reloc_continue;
+
   *error_message = "Unsupported call to elfNN_ia64_reloc";
   return bfd_reloc_notsupported;
 }
@@ -1701,19 +1705,25 @@ elfNN_ia64_hash_table_create (abfd)
 {
   struct elfNN_ia64_link_hash_table *ret;
 
-  ret = bfd_zalloc (abfd, (bfd_size_type) sizeof (*ret));
+  ret = bfd_malloc ((bfd_size_type) sizeof (*ret));
   if (!ret)
     return 0;
+  memset (ret, 0, sizeof (*ret));
+
   if (!_bfd_elf_link_hash_table_init (&ret->root, abfd,
 				      elfNN_ia64_new_elf_hash_entry))
     {
-      bfd_release (abfd, ret);
+      free (ret);
       return 0;
     }
 
   if (!elfNN_ia64_local_hash_table_init (&ret->loc_hash_table, abfd,
 				         elfNN_ia64_new_loc_hash_entry))
-    return 0;
+    {
+      free (ret);
+      return 0;
+    }
+
   return &ret->root.root;
 }
 
Index: bfd/simple.c
===================================================================
RCS file: /big/fsf/rsync/src-cvs/src/bfd/simple.c,v
retrieving revision 1.5
diff -u -p -r1.5 simple.c
--- bfd/simple.c	30 Nov 2002 08:39:40 -0000	1.5
+++ bfd/simple.c	4 Feb 2003 15:28:20 -0000
@@ -42,8 +42,14 @@ static bfd_boolean simple_dummy_reloc_da
 static bfd_boolean simple_dummy_unattached_reloc
   PARAMS ((struct bfd_link_info *, const char *, bfd *, asection *, bfd_vma));
 
+static void simple_save_output_info
+  PARAMS ((bfd *, asection *, PTR));
+
+static void simple_restore_output_info
+  PARAMS ((bfd *, asection *, PTR));
+
 bfd_byte * bfd_simple_get_relocated_section_contents
-  PARAMS ((bfd *, asection *, bfd_byte *));
+  PARAMS ((bfd *, asection *, bfd_byte *, asymbol **));
 
 static bfd_boolean
 simple_dummy_warning (link_info, warning, symbol, abfd, section, address)
@@ -105,17 +111,48 @@ simple_dummy_unattached_reloc (link_info
   return TRUE;
 }
 
+struct saved_output_info
+{
+  bfd_vma offset;
+  asection *section;
+};
+
+static void
+simple_save_output_info (abfd, section, ptr)
+     bfd *abfd ATTRIBUTE_UNUSED;
+     asection *section;
+     PTR ptr;
+{
+  struct saved_output_info *output_info = (struct saved_output_info *) ptr;
+  output_info[section->index].offset = section->output_offset;
+  output_info[section->index].section = section->output_section;
+  section->output_offset = 0;
+  section->output_section = section;
+}
+
+static void
+simple_restore_output_info (abfd, section, ptr)
+     bfd *abfd ATTRIBUTE_UNUSED;
+     asection *section;
+     PTR ptr;
+{
+  struct saved_output_info *output_info = (struct saved_output_info *) ptr;
+  section->output_offset = output_info[section->index].offset;
+  section->output_section = output_info[section->index].section;
+}
+
 /*
 FUNCTION
 	bfd_simple_relocate_secton
 
 SYNOPSIS
-	bfd_byte *bfd_simple_get_relocated_section_contents (bfd *abfd, asection *sec, bfd_byte *outbuf);
+	bfd_byte *bfd_simple_get_relocated_section_contents (bfd *abfd, asection *sec, bfd_byte *outbuf, asymbol **symbol_table);
 
 DESCRIPTION
-	Returns the relocated contents of section @var{sec}.  Only symbols
-	from @var{abfd} and the output offsets assigned to sections in
-	@var{abfd} are used.  The result will be stored at @var{outbuf}
+	Returns the relocated contents of section @var{sec}.  The symbols in
+	@var{symbol_table} will be used, or the symbols from @var{abfd} if
+	@var{symbol_table} is NULL.  The output offsets for all sections will
+	be temporarily reset to 0.  The result will be stored at @var{outbuf}
 	or allocated with @code{bfd_malloc} if @var{outbuf} is @code{NULL}.
 
 	Generally all sections in @var{abfd} should have their
@@ -126,17 +163,18 @@ DESCRIPTION
 */
 
 bfd_byte *
-bfd_simple_get_relocated_section_contents (abfd, sec, outbuf)
+bfd_simple_get_relocated_section_contents (abfd, sec, outbuf, symbol_table)
      bfd *abfd;
      asection *sec;
      bfd_byte *outbuf;
+     asymbol **symbol_table;
 {
   struct bfd_link_info link_info;
   struct bfd_link_order link_order;
   struct bfd_link_callbacks callbacks;
   bfd_byte *contents, *data;
   int storage_needed, number_of_symbols;
-  asymbol **symbol_table;
+  PTR saved_offsets;
 
   if (! (sec->flags & SEC_RELOC))
     {
@@ -183,11 +221,36 @@ bfd_simple_get_relocated_section_content
 	return NULL;
       outbuf = data;
     }
-  bfd_link_add_symbols (abfd, &link_info);
 
-  storage_needed = bfd_get_symtab_upper_bound (abfd);
-  symbol_table = (asymbol **) bfd_malloc (storage_needed);
-  number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
+  /* The sections in ABFD may already have output sections and offsets set.
+     Because this function is primarily for debug sections, and GCC uses the
+     knowledge that debug sections will generally have VMA 0 when emiting
+     relocations between DWARF-2 sections (which are supposed to be
+     section-relative offsets anyway), we need to reset the output offsets
+     to zero.  We also need to arrange for section->output_section->vma plus
+     section->output_offset to equal section->vma, which we do by setting
+     section->output_section to point back to section.  Save the original
+     output offset and output section to restore later.  */
+  saved_offsets = malloc (sizeof (struct saved_output_info)
+			  * abfd->section_count);
+  if (saved_offsets == NULL)
+    {
+      if (data)
+	free (data);
+      return NULL;
+    }
+  bfd_map_over_sections (abfd, simple_save_output_info, saved_offsets);
+
+  if (symbol_table == NULL)
+    {
+      bfd_link_add_symbols (abfd, &link_info);
+
+      storage_needed = bfd_get_symtab_upper_bound (abfd);
+      symbol_table = (asymbol **) bfd_malloc (storage_needed);
+      number_of_symbols = bfd_canonicalize_symtab (abfd, symbol_table);
+    }
+  else
+    storage_needed = 0;
 
   contents = bfd_get_relocated_section_contents (abfd,
 						 &link_info,
@@ -197,6 +260,12 @@ bfd_simple_get_relocated_section_content
 						 symbol_table);
   if (contents == NULL && data != NULL)
     free (data);
+
+  if (storage_needed != 0)
+    free (symbol_table);
+
+  bfd_map_over_sections (abfd, simple_restore_output_info, saved_offsets);
+  free (saved_offsets);
 
   /* Foul hack to prevent bfd_section_size aborts.  This flag only controls
      that macro (and the related size macros), selecting between _raw_size


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