Change type and size of symbols created by annobin to STT_NOTYPE/size 0. See BZ...

Update documentation to describe the global-file-sym option.

diff --git a/doc/annobin.info b/doc/annobin.info
index 2da14708ca34e05001a498e1630c4e14c203575c..e0fd102fb0a13bb60600454554ac3e718c161381 100644 (file)
--- a/doc/annobin.info
+++ b/doc/annobin.info
@@ -34,11 +34,11 @@ the section entitled "GNU Free Documentation License".
 
 * Menu:
 
-* Introduction::        What is Binary Annotation ?
-* Invocation::          How to add Binary Annotations to your application.
-* Checking::            How to examine the information stored in the binary.
-* Using::               How to use the information stored in the binary.
-* GNU Free Documentation License::  GNU Free Documentation License
+* Introduction::    What is Binary Annotation ?
+* Invocation::      How to add Binary Annotations to your application.
+* Checking::        How to examine the information stored in the binary.
+* Using::           How to use the information stored in the binary.
+* GNU FDL::         GNU Free Documentation License
 
 \1f
 File: annobin.info,  Node: Introduction,  Next: Invocation,  Prev: Top,  Up: Top
@@ -94,11 +94,17 @@ is enabled automatically by the build system, so no user intervention is
 required.  On Fedora and RHEL based systems this is handled by the
 'redhat-rpm-config' package.
 
-   If necessary however the binary annotation plugin can be specifically
-added to the gcc command line by adding the '-fplugin=annobin' option.
-It may also be necessary to tell gcc where to find plugins by adding the
-'-iplugindir=' option, although this should only be necessary if the
-plugin is installed in a separate place from 'gcc'.
+   Currently the binary annotations are generated by a plugin to the
+'GCC' compiler called 'annobin'.  This does mean that files that are not
+compiled with 'GCC' will not gain any binary annotations.  Solving this
+problem is one of the future goals of the annobin project.
+
+   If the build system being used does not automatically enabled the
+'annobin' plugin then it can be specifically added to the gcc command
+line by adding the '-fplugin=annobin' option.  It may also be necessary
+to tell gcc where to find plugins by adding the '-iplugindir=' option,
+although this should only be necessary if the plugin is installed in a
+separate place from 'gcc'.
 
    If it is desired to disable the recording of binary annotations then
 the '-fplugin-arg-annobin-disable' can be used, although this must be
@@ -154,6 +160,21 @@ after the plugin itself is mentioned.  The options are:
      bytes of static stack space will not have their requirements
      recorded.  If not set, then 'N' defaults to 1024.
 
+'global-file-syms'
+'no-global-file-syms'
+     If enabled the 'global-file-syms' option will create globally
+     visible, unique symbols to mark the start and end of the compiled
+     code.  This can be desirable if a program consists of multiple
+     source files with the same name, or if it links to a library that
+     was built with source files of the same name as the program itself.
+     The disadvantage of this feature however is that the unique names
+     are based upon the time of the build, so repeated builds of the
+     same source will have different symbol names inside it.  This
+     breaks the functionality of the build-id system which is meant to
+     identify similar builds created at different times.  This feature
+     is disabled by default, and if enabled can be disabled again via
+     the 'no-global-file-syms' option.
+
 \1f
 File: annobin.info,  Node: Checking,  Next: Using,  Prev: Invocation,  Up: Top
 
@@ -310,7 +331,7 @@ of bytes that indicate various different flags:
      2 (set).
 
 \1f
-File: annobin.info,  Node: Using,  Next: GNU Free Documentation License,  Prev: Checking,  Up: Top
+File: annobin.info,  Node: Using,  Next: GNU FDL,  Prev: Checking,  Up: Top
 
 4 How to use the information stored in the binary.
 **************************************************
@@ -742,7 +763,7 @@ by the 'find' command, like this:
      to be run with a program whoes name starts with a dash.
 
 \1f
-File: annobin.info,  Node: GNU Free Documentation License,  Prev: Using,  Up: Top
+File: annobin.info,  Node: GNU FDL,  Prev: Using,  Up: Top
 
 Appendix A GNU Free Documentation License
 *****************************************
@@ -1227,18 +1248,18 @@ their use in free software.
 \1f
 Tag Table:
 Node: Top\7f706
-Node: Introduction\7f1616
-Node: Invocation\7f3718
-Node: Checking\7f6549
-Node: The Version Encoding\7f8836
-Node: The GOW Encoding\7f9181
-Node: The CF Encoding\7f10632
-Node: The CET Encoding\7f11702
-Node: Using\7f12470
-Node: Who Built Me\7f13008
-Node: ABI Checking\7f15786
-Node: Hardening Checks\7f17914
-Node: Checking Archives\7f21756
-Node: GNU Free Documentation License\7f24194
+Node: Introduction\7f1584
+Node: Invocation\7f3686
+Node: Checking\7f7683
+Node: The Version Encoding\7f9970
+Node: The GOW Encoding\7f10315
+Node: The CF Encoding\7f11766
+Node: The CET Encoding\7f12836
+Node: Using\7f13604
+Node: Who Built Me\7f14119
+Node: ABI Checking\7f16897
+Node: Hardening Checks\7f19025
+Node: Checking Archives\7f22867
+Node: GNU FDL\7f25305
 \1f
 End Tag Table

diff --git a/doc/annobin.texi b/doc/annobin.texi
index c43b3d0a1beb8032016c6c3a4f178b3c28045016..17946419cd0c3995e529d7e705e3928230d2fc80 100644 (file)
--- a/doc/annobin.texi
+++ b/doc/annobin.texi
@@ -7,7 +7,7 @@
 @c man begin INCLUDE
 @set VERSION 3.2
 @set VERSION_PACKAGE (Annobin) 
-@set UPDATED January 2018
+@set UPDATED February 2018
 @c man end
 
 @ifnottex
@@ -84,11 +84,11 @@ Documentation License version 1.3.  A copy of the license is included
 in the section entitled ``GNU Free Documentation License''.
 
 @menu
-* Introduction::        What is Binary Annotation ?
-* Invocation::          How to add Binary Annotations to your application.
-* Checking::            How to examine the information stored in the binary.
-* Using::               How to use the information stored in the binary.
-* GNU Free Documentation License::  GNU Free Documentation License
+* Introduction::    What is Binary Annotation ?
+* Invocation::      How to add Binary Annotations to your application.
+* Checking::        How to examine the information stored in the binary.
+* Using::           How to use the information stored in the binary.
+* GNU FDL::         GNU Free Documentation License
 @end menu
 @end ifnottex
 
@@ -143,12 +143,18 @@ is enabled automatically by the build system, so no user intervention
 is required.  On Fedora and RHEL based systems this is handled by the
 @samp{redhat-rpm-config} package.
 
-If necessary however the binary annotation plugin can be specifically
-added to the gcc command line by adding the @option{-fplugin=annobin}
-option.  It may also be necessary to tell gcc where to find plugins by
-adding the @option{-iplugindir=} option, although this should only be
-necessary if the plugin is installed in a separate place from
-@code{gcc}.
+Currently the binary annotations are generated by a plugin to the
+@code{GCC} compiler called @samp{annobin}.  This does mean that files
+that are not compiled with @code{GCC} will not gain any binary
+annotations.  Solving this problem is one of the future goals of the
+annobin project.
+
+If the build system being used does not automatically enabled the
+@samp{annobin} plugin then it can be specifically added to the gcc
+command line by adding the @option{-fplugin=annobin} option.  It may
+also be necessary to tell gcc where to find plugins by adding the
+@option{-iplugindir=} option, although this should only be necessary
+if the plugin is installed in a separate place from @code{gcc}.
 
 If it is desired to disable the recording of binary annotations then
 the @option{-fplugin-arg-annobin-disable} can be used, although this
@@ -204,6 +210,21 @@ the minimum value to record.  Functions which require less than
 @code{N} bytes of static stack space will not have their requirements
 recorded.  If not set, then @code{N} defaults to 1024.
 
+@item global-file-syms
+@itemx no-global-file-syms
+If enabled the @option{global-file-syms} option will create globally
+visible, unique symbols to mark the start and end of the compiled
+code.  This can be desirable if a program consists of multiple source
+files with the same name, or if it links to a library that was built
+with source files of the same name as the program itself.  The
+disadvantage of this feature however is that the unique names are
+based upon the time of the build, so repeated builds of the same
+source will have different symbol names inside it.  This breaks the
+functionality of the build-id system which is meant to identify
+similar builds created at different times.  This feature is disabled
+by default, and if enabled can be disabled again via the
+@option{no-global-file-syms} option.
+
 @end table
 
 @c -----------------------------------------------------------------
@@ -811,7 +832,7 @@ be run with a program whoes name starts with a dash.
 @end table
 
 @c -----------------------------------------------------------------
-@node GNU Free Documentation License
+@node GNU FDL
 @appendix GNU Free Documentation License
 @include fdl.texi
 

diff --git a/plugin/annobin.cc b/plugin/annobin.cc
index e4a3c27ec7318c4cff4dcff6b1a49e37c0003a36..41709cb6aa9c48dcab2aed795ca496bddf7d2407 100644 (file)
--- a/plugin/annobin.cc
+++ b/plugin/annobin.cc
@@ -98,7 +98,10 @@ static struct plugin_info annobin_info =
    Since there can be multiple input files, we choose the main output
    filename (stripped of any path prefixes).  Since filenames can
    contain characters that symbol names do not (eg '-') we have to
-   allocate our own name.  */
+   allocate our own name.
+
+   FIXME: Currently we do not create symbols for other sections that
+   might contain generate code.  Eg because of __attribute__((section)).  */
 
 static void
 init_annobin_current_filename (void)
@@ -310,9 +313,6 @@ annobin_output_note (const char * name,
     {
       if (desc_is_string)
        {
-         /* The DESCRIPTION string is the name of a symbol.  We want to produce
-            a reference to this symbol of the appropriate size for the target
-            architecture.  */
          if (annobin_is_64bit)
            fprintf (asm_out_file, "\t.quad %s", (char *) desc1);
          else
@@ -845,9 +845,22 @@ annobin_create_global_notes (void * gcc_data, void * user_data)
   /* Create a symbol for this compilation unit.  */
   if (global_file_name_symbols)
     fprintf (asm_out_file, ".global %s\n", annobin_current_filename);
-  fprintf (asm_out_file, ".type %s STT_OBJECT\n", annobin_current_filename);
-  fprintf (asm_out_file, ".size %s, %s - %s\n",annobin_current_filename, annobin_current_endname, annobin_current_filename);
+
+  /* Note - we used to set the type of the symbol to STT_OBJECT, but that is
+     incorrect because that type is for:
+       "A data object, such as a variable, an array, and so on".
+
+     There is no ELF symbol to represent a compilation unit, (STT_FILE only
+     covers a single source file and has special sematic requirements), so
+     instead we use STT_NOTYPE.  (Ideally we could use STT_LOOS+n, but there
+     is a problem with the GAS assembler, which does not allow such values to
+     be set on symbols).  */
+  fprintf (asm_out_file, ".type %s, STT_NOTYPE\n", annobin_current_filename);
   fprintf (asm_out_file, "%s:\n", annobin_current_filename);
+  /* We explicitly set the size of the symbol to 0 so that it will not
+     confuse other tools (eg GDB, elfutils) which look for symbols that
+     cover an address range.  */
+  fprintf (asm_out_file, ".size %s, 0\n", annobin_current_filename);
 
   /* Create the static notes section.  */
 #ifdef OLD_GAS
@@ -979,6 +992,10 @@ annobin_create_loader_notes (void * gcc_data, void * user_data)
   /* FIXME: This assumes that functions are being placed into the .text section.  */
   fprintf (asm_out_file, "\t.pushsection .text\n");
   fprintf (asm_out_file, "%s:\n", annobin_current_endname);
+  if (global_file_name_symbols)
+    fprintf (asm_out_file, ".global %s\n", annobin_current_endname);
+  fprintf (asm_out_file, ".type %s, STT_NOTYPE\n", annobin_current_endname);
+  fprintf (asm_out_file, ".size %s, 0\n", annobin_current_endname);
   fprintf (asm_out_file, "\t.popsection\n");
 
   if (! annobin_enable_dynamic_notes)

diff --git a/tests/Makefile.in b/tests/Makefile.in
index f82468283004932195598af0bd4ee2791ca3e5ec..4504931f41d82fb4962a62ecdb0e661ddc7fac1f 100644 (file)
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -467,6 +467,7 @@ uninstall-am:
 
 
 # FIXME: Add a test for merging notes...
+# FIXME: Add a test for examining archives...
 
 # Tell versions [3.59,3.63) of GNU make to not export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.