scripts/namespace.pl

   1 #!/usr/bin/perl -w
   2 #
   3 #       namespace.pl.  Mon Aug 30 2004
   4 #
   5 #       Perform a name space analysis on the linux kernel.
   6 #
   7 #       Copyright Keith Owens <kaos@ocs.com.au>.  GPL.
   8 #
   9 #       Invoke by changing directory to the top of the kernel object
  10 #       tree then namespace.pl, no parameters.
  11 #
  12 #       Tuned for 2.1.x kernels with the new module handling, it will
  13 #       work with 2.0 kernels as well.
  14 #
  15 #       Last change 2.6.9-rc1, adding support for separate source and object
  16 #       trees.
  17 #
  18 #       The source must be compiled/assembled first, the object files
  19 #       are the primary input to this script.  Incomplete or missing
  20 #       objects will result in a flawed analysis.  Compile both vmlinux
  21 #       and modules.
  22 #
  23 #       Even with complete objects, treat the result of the analysis
  24 #       with caution.  Some external references are only used by
  25 #       certain architectures, others with certain combinations of
  26 #       configuration parameters.  Ideally the source should include
  27 #       something like
  28 #
  29 #       #ifndef CONFIG_...
  30 #       static
  31 #       #endif
  32 #       symbol_definition;
  33 #
  34 #       so the symbols are defined as static unless a particular
  35 #       CONFIG_... requires it to be external.
  36 #
  37 #       A symbol that is suffixed with '(export only)' has these properties
  38 #
  39 #       * It is global.
  40 #       * It is marked EXPORT_SYMBOL or EXPORT_SYMBOL_GPL, either in the same
  41 #         source file or a different source file.
  42 #       * Given the current .config, nothing uses the symbol.
  43 #
  44 #       The symbol is a candidate for conversion to static, plus removal of the
  45 #       export.  But be careful that a different .config might use the symbol.
  46 #
  47 #
  48 #       Name space analysis and cleanup is an iterative process.  You cannot
  49 #       expect to find all the problems in a single pass.
  50 #
  51 #       * Identify possibly unnecessary global declarations, verify that they
  52 #         really are unnecessary and change them to static.
  53 #       * Compile and fix up gcc warnings about static, removing dead symbols
  54 #         as necessary.
  55 #       * make clean and rebuild with different configs (especially
  56 #         CONFIG_MODULES=n) to see which symbols are being defined when the
  57 #         config does not require them.  These symbols bloat the kernel object
  58 #         for no good reason, which is frustrating for embedded systems.
  59 #       * Wrap config sensitive symbols in #ifdef CONFIG_foo, as long as the
  60 #         code does not get too ugly.
  61 #       * Repeat the name space analysis until you can live with with the
  62 #         result.
  63 #
  64
  65 require 5;      # at least perl 5
  66 use strict;
  67 use File::Find;
  68
  69 my $nm = "/usr/bin/nm -p";
  70 my $objdump = "/usr/bin/objdump -s -j .comment";
  71 my $srctree = "";
  72 my $objtree = "";
  73 $srctree = "$ENV{'srctree'}/" if (exists($ENV{'srctree'}));
  74 $objtree = "$ENV{'objtree'}/" if (exists($ENV{'objtree'}));
  75
  76 if ($#ARGV != -1) {
  77         print STDERR "usage: $0 takes no parameters\n";
  78         die("giving up\n");
  79 }
  80
  81 my %nmdata = ();        # nm data for each object
  82 my %def = ();           # all definitions for each name
  83 my %ksymtab = ();       # names that appear in __ksymtab_
  84 my %ref = ();           # $ref{$name} exists if there is a true external reference to $name
  85 my %export = ();        # $export{$name} exists if there is an EXPORT_... of $name
  86
  87 &find(\&linux_objects, '.');    # find the objects and do_nm on them
  88 &list_multiply_defined();
  89 &resolve_external_references();
  90 &list_extra_externals();
  91
  92 exit(0);
  93
  94 sub linux_objects
  95 {
  96         # Select objects, ignoring objects which are only created by
  97         # merging other objects.  Also ignore all of modules, scripts
  98         # and compressed.  Most conglomerate objects are handled by do_nm,
  99         # this list only contains the special cases.  These include objects
 100         # that are linked from just one other object and objects for which
 101         # there is really no permanent source file.
 102         my $basename = $_;
 103         $_ = $File::Find::name;
 104         s:^\./::;
 105         if (/.*\.o$/ &&
 106                 ! (
 107                 m:/built-in.o$:
 108                 || m:arch/i386/kernel/vsyscall-syms.o$:
 109                 || m:arch/ia64/ia32/ia32.o$:
 110                 || m:arch/ia64/kernel/gate-syms.o$:
 111                 || m:arch/ia64/lib/__divdi3.o$:
 112                 || m:arch/ia64/lib/__divsi3.o$:
 113                 || m:arch/ia64/lib/__moddi3.o$:
 114                 || m:arch/ia64/lib/__modsi3.o$:
 115                 || m:arch/ia64/lib/__udivdi3.o$:
 116                 || m:arch/ia64/lib/__udivsi3.o$:
 117                 || m:arch/ia64/lib/__umoddi3.o$:
 118                 || m:arch/ia64/lib/__umodsi3.o$:
 119                 || m:arch/ia64/scripts/check_gas_for_hint.o$:
 120                 || m:arch/ia64/sn/kernel/xp.o$:
 121                 || m:boot/bbootsect.o$:
 122                 || m:boot/bsetup.o$:
 123                 || m:/bootsect.o$:
 124                 || m:/boot/setup.o$:
 125                 || m:/compressed/:
 126                 || m:drivers/cdrom/driver.o$:
 127                 || m:drivers/char/drm/tdfx_drv.o$:
 128                 || m:drivers/ide/ide-detect.o$:
 129                 || m:drivers/ide/pci/idedriver-pci.o$:
 130                 || m:drivers/media/media.o$:
 131                 || m:drivers/scsi/sd_mod.o$:
 132                 || m:drivers/video/video.o$:
 133                 || m:fs/devpts/devpts.o$:
 134                 || m:fs/exportfs/exportfs.o$:
 135                 || m:fs/hugetlbfs/hugetlbfs.o$:
 136                 || m:fs/msdos/msdos.o$:
 137                 || m:fs/nls/nls.o$:
 138                 || m:fs/ramfs/ramfs.o$:
 139                 || m:fs/romfs/romfs.o$:
 140                 || m:fs/vfat/vfat.o$:
 141                 || m:init/mounts.o$:
 142                 || m:^modules/:
 143                 || m:net/netlink/netlink.o$:
 144                 || m:net/sched/sched.o$:
 145                 || m:/piggy.o$:
 146                 || m:^scripts/:
 147                 || m:sound/.*/snd-:
 148                 || m:^.*/\.tmp_:
 149                 || m:^\.tmp_:
 150                 || m:/vmlinux-obj.o$:
 151                 )
 152         ) {
 153                 do_nm($basename, $_);
 154         }
 155         $_ = $basename;         # File::Find expects $_ untouched (undocumented)
 156 }
 157
 158 sub do_nm
 159 {
 160         my ($basename, $fullname) = @_;
 161         my ($source, $type, $name);
 162         if (! -e $basename) {
 163                 printf STDERR "$basename does not exist\n";
 164                 return;
 165         }
 166         if ($fullname !~ /\.o$/) {
 167                 printf STDERR "$fullname is not an object file\n";
 168                 return;
 169         }
 170         ($source = $fullname) =~ s/\.o$//;
 171         if (-e "$objtree$source.c" || -e "$objtree$source.S") {
 172                 $source = "$objtree$source";
 173         } else {
 174                 $source = "$srctree$source";
 175         }
 176         if (! -e "$source.c" && ! -e "$source.S") {
 177                 # No obvious source, exclude the object if it is conglomerate
 178                 if (! open(OBJDUMPDATA, "$objdump $basename|")) {
 179                         printf STDERR "$objdump $fullname failed $!\n";
 180                         return;
 181                 }
 182                 my $comment;
 183                 while (<OBJDUMPDATA>) {
 184                         chomp();
 185                         if (/^In archive/) {
 186                                 # Archives are always conglomerate
 187                                 $comment = "GCC:GCC:";
 188                                 last;
 189                         }
 190                         next if (! /^[ 0-9a-f]{5,} /);
 191                         $comment .= substr($_, 43);
 192                 }
 193                 close(OBJDUMPDATA);
 194                 if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) {
 195                         printf STDERR "No source file found for $fullname\n";
 196                 }
 197                 return;
 198         }
 199         if (! open(NMDATA, "$nm $basename|")) {
 200                 printf STDERR "$nm $fullname failed $!\n";
 201                 return;
 202         }
 203         my @nmdata;
 204         while (<NMDATA>) {
 205                 chop;
 206                 ($type, $name) = (split(/ +/, $_, 3))[1..2];
 207                 # Expected types
 208                 # A absolute symbol
 209                 # B weak external reference to data that has been resolved
 210                 # C global variable, uninitialised
 211                 # D global variable, initialised
 212                 # G global variable, initialised, small data section
 213                 # R global array, initialised
 214                 # S global variable, uninitialised, small bss
 215                 # T global label/procedure
 216                 # U external reference
 217                 # W weak external reference to text that has been resolved
 218                 # a assembler equate
 219                 # b static variable, uninitialised
 220                 # d static variable, initialised
 221                 # g static variable, initialised, small data section
 222                 # r static array, initialised
 223                 # s static variable, uninitialised, small bss
 224                 # t static label/procedures
 225                 # w weak external reference to text that has not been resolved
 226                 # ? undefined type, used a lot by modules
 227                 if ($type !~ /^[ABCDGRSTUWabdgrstw?]$/) {
 228                         printf STDERR "nm output for $fullname contains unknown type '$_'\n";
 229                 }
 230                 elsif ($name =~ /\./) {
 231                         # name with '.' is local static
 232                 }
 233                 else {
 234                         $type = 'R' if ($type eq '?');  # binutils replaced ? with R at one point
 235                         # binutils keeps changing the type for exported symbols, force it to R
 236                         $type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/);
 237                         $name =~ s/_R[a-f0-9]{8}$//;    # module versions adds this
 238                         if ($type =~ /[ABCDGRSTW]/ &&
 239                                 $name ne 'init_module' &&
 240                                 $name ne 'cleanup_module' &&
 241                                 $name ne 'Using_Versions' &&
 242                                 $name !~ /^Version_[0-9]+$/ &&
 243                                 $name !~ /^__parm_/ &&
 244                                 $name !~ /^__kstrtab/ &&
 245                                 $name !~ /^__ksymtab/ &&
 246                                 $name !~ /^__kcrctab_/ &&
 247                                 $name !~ /^__exitcall_/ &&
 248                                 $name !~ /^__initcall_/ &&
 249                                 $name !~ /^__kdb_initcall_/ &&
 250                                 $name !~ /^__kdb_exitcall_/ &&
 251                                 $name !~ /^__module_/ &&
 252                                 $name !~ /^__mod_/ &&
 253                                 $name !~ /^__crc_/ &&
 254                                 $name ne '__this_module' &&
 255                                 $name ne 'kernel_version') {
 256                                 if (!exists($def{$name})) {
 257                                         $def{$name} = [];
 258                                 }
 259                                 push(@{$def{$name}}, $fullname);
 260                         }
 261                         push(@nmdata, "$type $name");
 262                         if ($name =~ /^__ksymtab_/) {
 263                                 $name = substr($name, 10);
 264                                 if (!exists($ksymtab{$name})) {
 265                                         $ksymtab{$name} = [];
 266                                 }
 267                                 push(@{$ksymtab{$name}}, $fullname);
 268                         }
 269                 }
 270         }
 271         close(NMDATA);
 272         if ($#nmdata < 0) {
 273                 if (
 274                         $fullname ne "lib/brlock.o"
 275                         && $fullname ne "lib/dec_and_lock.o"
 276                         && $fullname ne "fs/xfs/xfs_macros.o"
 277                         && $fullname ne "drivers/ide/ide-probe-mini.o"
 278                         && $fullname ne "usr/initramfs_data.o"
 279                         && $fullname ne "drivers/acpi/executer/exdump.o"
 280                         && $fullname ne "drivers/acpi/resources/rsdump.o"
 281                         && $fullname ne "drivers/acpi/namespace/nsdumpdv.o"
 282                         && $fullname ne "drivers/acpi/namespace/nsdump.o"
 283                         && $fullname ne "arch/ia64/sn/kernel/sn2/io.o"
 284                         && $fullname ne "arch/ia64/kernel/gate-data.o"
 285                         && $fullname ne "drivers/ieee1394/oui.o"
 286                         && $fullname ne "security/capability.o"
 287                         && $fullname ne "sound/core/wrappers.o"
 288                         && $fullname ne "fs/ntfs/sysctl.o"
 289                         && $fullname ne "fs/jfs/jfs_debug.o"
 290                 ) {
 291                         printf "No nm data for $fullname\n";
 292                 }
 293                 return;
 294         }
 295         $nmdata{$fullname} = \@nmdata;
 296 }
 297
 298 sub drop_def
 299 {
 300         my ($object, $name) = @_;
 301         my $nmdata = $nmdata{$object};
 302         my ($i, $j);
 303         for ($i = 0; $i <= $#{$nmdata}; ++$i) {
 304                 if ($name eq (split(' ', $nmdata->[$i], 2))[1]) {
 305                         splice(@{$nmdata{$object}}, $i, 1);
 306                         my $def = $def{$name};
 307                         for ($j = 0; $j < $#{$def{$name}}; ++$j) {
 308                                 if ($def{$name}[$j] eq $object) {
 309                                         splice(@{$def{$name}}, $j, 1);
 310                                 }
 311                         }
 312                         last;
 313                 }
 314         }
 315 }
 316
 317 sub list_multiply_defined
 318 {
 319         my ($name, $module);
 320         foreach $name (keys(%def)) {
 321                 if ($#{$def{$name}} > 0) {
 322                         # Special case for cond_syscall
 323                         if ($#{$def{$name}} == 1 && $name =~ /^sys_/ &&
 324                             ($def{$name}[0] eq "kernel/sys.o" ||
 325                              $def{$name}[1] eq "kernel/sys.o")) {
 326                                 &drop_def("kernel/sys.o", $name);
 327                                 next;
 328                         }
 329                         # Special case for i386 entry code
 330                         if ($#{$def{$name}} == 1 && $name =~ /^__kernel_/ &&
 331                             $def{$name}[0] eq "arch/i386/kernel/vsyscall-int80.o" &&
 332                             $def{$name}[1] eq "arch/i386/kernel/vsyscall-sysenter.o") {
 333                                 &drop_def("arch/i386/kernel/vsyscall-sysenter.o", $name);
 334                                 next;
 335                         }
 336                         printf "$name is multiply defined in :-\n";
 337                         foreach $module (@{$def{$name}}) {
 338                                 printf "\t$module\n";
 339                         }
 340                 }
 341         }
 342 }
 343
 344 sub resolve_external_references
 345 {
 346         my ($object, $type, $name, $i, $j, $kstrtab, $ksymtab, $export);
 347         printf "\n";
 348         foreach $object (keys(%nmdata)) {
 349                 my $nmdata = $nmdata{$object};
 350                 for ($i = 0; $i <= $#{$nmdata}; ++$i) {
 351                         ($type, $name) = split(' ', $nmdata->[$i], 2);
 352                         if ($type eq "U" || $type eq "w") {
 353                                 if (exists($def{$name}) || exists($ksymtab{$name})) {
 354                                         # add the owning object to the nmdata
 355                                         $nmdata->[$i] = "$type $name $object";
 356                                         # only count as a reference if it is not EXPORT_...
 357                                         $kstrtab = "R __kstrtab_$name";
 358                                         $ksymtab = "R __ksymtab_$name";
 359                                         $export = 0;
 360                                         for ($j = 0; $j <= $#{$nmdata}; ++$j) {
 361                                                 if ($nmdata->[$j] eq $kstrtab ||
 362                                                     $nmdata->[$j] eq $ksymtab) {
 363                                                         $export = 1;
 364                                                         last;
 365                                                 }
 366                                         }
 367                                         if ($export) {
 368                                                 $export{$name} = "";
 369                                         }
 370                                         else {
 371                                                 $ref{$name} = ""
 372                                         }
 373                                 }
 374                                 elsif (    $name ne "mod_use_count_"
 375                                         && $name ne "__initramfs_end"
 376                                         && $name ne "__initramfs_start"
 377                                         && $name ne "_einittext"
 378                                         && $name ne "_sinittext"
 379                                         && $name ne "kallsyms_names"
 380                                         && $name ne "kallsyms_num_syms"
 381                                         && $name ne "kallsyms_addresses"
 382                                         && $name ne "__this_module"
 383                                         && $name ne "_etext"
 384                                         && $name ne "_edata"
 385                                         && $name ne "_end"
 386                                         && $name ne "__bss_start"
 387                                         && $name ne "_text"
 388                                         && $name ne "_stext"
 389                                         && $name ne "__gp"
 390                                         && $name ne "ia64_unw_start"
 391                                         && $name ne "ia64_unw_end"
 392                                         && $name ne "__init_begin"
 393                                         && $name ne "__init_end"
 394                                         && $name ne "__bss_stop"
 395                                         && $name ne "__nosave_begin"
 396                                         && $name ne "__nosave_end"
 397                                         && $name ne "pg0"
 398                                         && $name ne "__module_text_address"
 399                                         && $name !~ /^__sched_text_/
 400                                         && $name !~ /^__start_/
 401                                         && $name !~ /^__end_/
 402                                         && $name !~ /^__stop_/
 403                                         && $name !~ /^__scheduling_functions_.*_here/
 404                                         && $name !~ /^__.*initcall_/
 405                                         && $name !~ /^__.*per_cpu_start/
 406                                         && $name !~ /^__.*per_cpu_end/
 407                                         && $name !~ /^__alt_instructions/
 408                                         && $name !~ /^__setup_/
 409                                         && $name !~ /^jiffies/
 410                                         && $name !~ /^__mod_timer/
 411                                         && $name !~ /^__mod_page_state/
 412                                         && $name !~ /^init_module/
 413                                         && $name !~ /^cleanup_module/
 414                                 ) {
 415                                         printf "Cannot resolve ";
 416                                         printf "weak " if ($type eq "w");
 417                                         printf "reference to $name from $object\n";
 418                                 }
 419                         }
 420                 }
 421         }
 422 }
 423
 424 sub list_extra_externals
 425 {
 426         my %noref = ();
 427         my ($name, @module, $module, $export);
 428         foreach $name (keys(%def)) {
 429                 if (! exists($ref{$name})) {
 430                         @module = @{$def{$name}};
 431                         foreach $module (@module) {
 432                                 if (! exists($noref{$module})) {
 433                                         $noref{$module} = [];
 434                                 }
 435                                 push(@{$noref{$module}}, $name);
 436                         }
 437                 }
 438         }
 439         if (%noref) {
 440                 printf "\nExternally defined symbols with no external references\n";
 441                 foreach $module (sort(keys(%noref))) {
 442                         printf "  $module\n";
 443                         foreach (sort(@{$noref{$module}})) {
 444                                 if (exists($export{$_})) {
 445                                         $export = " (export only)";
 446                                 }
 447                                 else {
 448                                         $export = "";
 449                                 }
 450                                 printf "    $_$export\n";
 451                         }
 452                 }
 453         }
 454 }