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Nick Clifton dda8d76d0d Add support to readelf and objdump for following links to separate debug information files.
Hi Guys,

  I am applying the rather large patch attached to this email to enhance
  the readelf and objdump programs so that they now have the ability to
  follow links to separate debug info files.  (As requested by PR
  15152).  So for example whereas before we had this output:

    $ readelf -wi main.exe

    Contents of the .debug_info section:
    [...]
    <15>   DW_AT_comp_dir    : (alt indirect string, offset: 0x30c)
    [...]

  With the new option enabled we get:

    $ readelf -wiK main.exe

    main.exe: Found separate debug info file: dwz.debug
    Contents of the .debug_info section (loaded from main.exe):
    [...]
    <15>   DW_AT_comp_dir    : (alt indirect string, offset: 0x30c) /home/nickc/Downloads/dwzm
    [...]

  The link following feature also means that we can get two lots of
  output if the same section exists in both the main file and the
  separate debug info file:

    $ readelf -wiK main.exe
    main.exe: Found separate debug info file: dwz.debug
    Contents of the .debug_info section (loaded from main.exe):
    [...]
    Contents of the .debug_info section (loaded from dwz.debug):
    [...]

  The patch also adds the ability to display the contents of debuglink
  sections:

    $ readelf -wk main.exe
    Contents of the .gnu_debugaltlink section:

      Separate debug info file: dwz.debug
      Build-ID (0x14 bytes):
     c4 a8 89 8d 64 cf 70 8a 35 68 21 f2 ed 24 45 3e 18 7a 7a 93

  Naturally there are long versions of these options (=follow-links and
  =links).  The documentation has been updated as well, and since both
  readelf and objdump use the same set of debug display options, I have
  moved the text into a separate file.  There are also a couple of new
  binutils tests to exercise the new behaviour.

  There are a couple of missing features in the current patch however,
  although I do intend to address them in follow up submissions:

  Firstly the code does not check the build-id inside separate debug
  info files when it is searching for a file specified by a
  .gnu_debugaltlink section.  It just assumes that if the file is there,
  then it contains the information being sought.

  Secondly I have not checked the DWARF-5 version of these link
  features, so there will probably be code to add there.

  Thirdly I have only implemented link following for the
  DW_FORM_GNU_strp_alt format.  Other alternate formats (eg
  DW_FORM_GNU_ref_alt) have yet to be implemented.

  Lastly, whilst implementing this feature I found it necessary to move
  some of the global variables used by readelf (eg section_headers) into
  a structure that can be passed around.  I have moved all of the global
  variables that were necessary to get the patch working, but I need to
  complete the operation and move the remaining, file-specific variables
  (eg dynamic_strings).

Cheers
  Nick

binutils	PR 15152
	* dwarf.h (enum dwarf_section_display_enum): Add gnu_debuglink,
	gnu_debugaltlink and separate_debug_str.
	(struct dwarf_section): Add filename field.
	Add prototypes for load_separate_debug_file, close_debug_file and
	open_debug_file.
	* dwarf.c (do_debug_links): New.
	(do_follow_links): New.
	(separate_debug_file, separate_debug_filename): New.
	(fetch_alt_indirect_string): New function.  Retrieves a string
	from the debug string table in the separate debug info file.
	(read_and_display_attr_value): Use it with DW_FORM_GNU_strp_alt.
	(load_debug_section_with_follow): New function.  Like
	load_debug_section, but if the first attempt fails, then tries
	again in the separate debug info file.
	(introduce): New function.
	(process_debug_info): Use load_debug_section_with_follow and
	introduce.
	(load_debug_info): Likewise.
	(display_debug_lines_raw): Likewise.
	(display_debug_lines_decoded): Likewise.
	(display_debug_macinfo): Likewise.
	(display_debug_macro): Likewise.
	(display_debug_abbrev): Likewise.
	(display_debug_loc): Likewise.
	(display_debug_str): Likewise.
	(display_debug_aranges): Likewise.
	(display_debug_addr); Likewise.
	(display_debug_frames): Likewise.
	(display_gdb_index): Likewise.
	(process_cu_tu_index): Likewise.
	(load_cu_tu_indexes): Likewise.
	(display_debug_links): New function.  Displays the contents of a
	.gnu_debuglink or .gnu_debugaltlink section.
	(calc_gnu_debuglink_ctc32):New function.  Calculates a CRC32
	value.
	(check_gnu_debuglink): New function.  Checks the CRC of a
	potential separate debug info file.
	(parse_gnu_debuglink): New function.  Reads a CRC value out of a
	.gnu_debuglink section.
	(check_gnu_debugaltlink): New function.
	(parse_gnu_debugaltlink): New function.  Reads the build-id value
	out of a .gnu_debugaltlink section.
	(load_separate_debug_info): New function.  Finds and loads a
	separate debug info file.
	(load_separate_debug_file): New function. Attempts to find and
	follow a link to a separate debug info file.
	(free_debug_memory): Free the separate debug info file
	information.
	(opts_table): Add "follow-links" and "links".
	(dwarf_select_sections_by_letters): Add "k" and "K".
	(debug_displays): Reformat.  Add .gnu-debuglink and
	.gnu_debugaltlink.
	Add an extra entry for .debug_str in a separate debug info file.
	* doc/binutils.texi: Move description of debug dump features
	common to both readelf and objdump into...
	* objdump.c (usage): Add -Wk and -WK.
	(load_specific_debug_section): Initialise the filename field in
	the dwarf_section structure.
	(close_debug_file): New function.
	(open_debug_file): New function.
	(dump_dwarf): Load and dump the separate debug info sections.
	* readelf.c (struct filedata): New structure.  Contains various
	variables that used to be global:
	(current_file_size, string_table, string_table_length, elf_header)
	(section_headers, program_headers, dump_sects, num_dump_sects):
	Move into filedata structure.
	(cmdline): New global variable.  Contains list of sections to dump
	by number, as specified on the command line.
	Add filedata parameter to most functions.
	(load_debug_section): Load the string table if it has not already
	been retrieved.
	(close_file): New function.
	(close_debug_file): New function.
	(open_file): New function.
	(open_debug_file): New function.
	(process_object): Process sections in any separate debug info files.
	* doc/debug.options.texi: New file.  Add description of =links and
	=follow-links options.
	* NEWS: Mention the new feature.
	* elfcomm.c: Have the byte gte functions take a const pointer.
	* elfcomm.h: Update prototypes.
	* testsuite/binutils-all/dw5.W: Update expected output.
	* testsuite/binutils-all/objdump.WL: Update expected output.
	* testsuite/binutils-all/objdump.exp: Add test of -WK and -Wk.
	* testsuite/binutils-all/readelf.exp: Add test of -wK and -wk.
	* testsuite/binutils-all/readelf.k: New file.
	* testsuite/binutils-all/objdump.Wk: New file.
	* testsuite/binutils-all/objdump.WK2: New file.
	* testsuite/binutils-all/linkdebug.s: New file.
	* testsuite/binutils-all/debuglink.s: New file.

gas	* testsuite/gas/avr/large-debug-line-table.d: Update expected
	output.
	* testsuite/gas/elf/dwarf2-11.d: Likewise.
	* testsuite/gas/elf/dwarf2-12.d: Likewise.
	* testsuite/gas/elf/dwarf2-13.d: Likewise.
	* testsuite/gas/elf/dwarf2-14.d: Likewise.
	* testsuite/gas/elf/dwarf2-15.d: Likewise.
	* testsuite/gas/elf/dwarf2-16.d: Likewise.
	* testsuite/gas/elf/dwarf2-17.d: Likewise.
	* testsuite/gas/elf/dwarf2-18.d: Likewise.
	* testsuite/gas/elf/dwarf2-5.d: Likewise.
	* testsuite/gas/elf/dwarf2-6.d: Likewise.
	* testsuite/gas/elf/dwarf2-7.d: Likewise.

ld	* testsuite/ld-avr/gc-section-debugline.d: Update expected
	output.
2017-11-15 11:34:03 +00:00
bfd Automatic date update in version.in 2017-11-15 00:00:25 +00:00
binutils Add support to readelf and objdump for following links to separate debug information files. 2017-11-15 11:34:03 +00:00
config
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gas Add support to readelf and objdump for following links to separate debug information files. 2017-11-15 11:34:03 +00:00
gdb Better make rule for arch/ files built for IPA 2017-11-15 09:59:12 +00:00
gold gold: Ignore def/ref from a dynamic object for special symbols 2017-11-08 16:02:50 -08:00
gprof Update the Hungarian translation in the gprof directory. 2017-10-05 14:10:27 +01:00
include PE: don't corrupt section flags when linking from ELF objects 2017-11-13 12:26:12 +01:00
intl Require ngettext in test of system gettext implementation 2017-11-07 15:56:44 +10:30
ld Add support to readelf and objdump for following links to separate debug information files. 2017-11-15 11:34:03 +00:00
libdecnumber
libiberty
opcodes x86: use correct register names 2017-11-15 08:52:05 +01:00
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sim FT32: support for FT32B processor - part 2/2 2017-11-01 18:36:51 -07:00
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		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

Much of the code and documentation enclosed is copyright by
the Free Software Foundation, Inc.  See the file COPYING or
COPYING.LIB in the various directories, for a description of the
GNU General Public License terms under which you can copy the files.

REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info
on where and how to report problems.