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Linux/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 $nm = ($ENV{'NM'} || "nm") . " -p";
 70 my $objdump = ($ENV{'OBJDUMP'} || "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 my %nmexception = (
 88     'fs/ext3/bitmap'                    => 1,
 89     'fs/ext4/bitmap'                    => 1,
 90     'arch/x86/lib/thunk_32'             => 1,
 91     'arch/x86/lib/cmpxchg'              => 1,
 92     'arch/x86/vdso/vdso32/note'         => 1,
 93     'lib/irq_regs'                      => 1,
 94     'usr/initramfs_data'                => 1,
 95     'drivers/scsi/aic94xx/aic94xx_dump' => 1,
 96     'drivers/scsi/libsas/sas_dump'      => 1,
 97     'lib/dec_and_lock'                  => 1,
 98     'drivers/ide/ide-probe-mini'        => 1,
 99     'usr/initramfs_data'                => 1,
100     'drivers/acpi/acpia/exdump'         => 1,
101     'drivers/acpi/acpia/rsdump'         => 1,
102     'drivers/acpi/acpia/nsdumpdv'       => 1,
103     'drivers/acpi/acpia/nsdump'         => 1,
104     'arch/ia64/sn/kernel/sn2/io'        => 1,
105     'arch/ia64/kernel/gate-data'        => 1,
106     'security/capability'               => 1,
107     'fs/ntfs/sysctl'                    => 1,
108     'fs/jfs/jfs_debug'                  => 1,
109 );
110 
111 my %nameexception = (
112     'mod_use_count_'     => 1,
113     '__initramfs_end'   => 1,
114     '__initramfs_start' => 1,
115     '_einittext'        => 1,
116     '_sinittext'        => 1,
117     'kallsyms_names'    => 1,
118     'kallsyms_num_syms' => 1,
119     'kallsyms_addresses'=> 1,
120     'kallsyms_offsets'  => 1,
121     'kallsyms_relative_base'=> 1,
122     '__this_module'     => 1,
123     '_etext'            => 1,
124     '_edata'            => 1,
125     '_end'              => 1,
126     '__bss_start'       => 1,
127     '_text'             => 1,
128     '_stext'            => 1,
129     '__gp'              => 1,
130     'ia64_unw_start'    => 1,
131     'ia64_unw_end'      => 1,
132     '__init_begin'      => 1,
133     '__init_end'        => 1,
134     '__bss_stop'        => 1,
135     '__nosave_begin'    => 1,
136     '__nosave_end'      => 1,
137     'pg0'               => 1,
138     'vdso_enabled'      => 1,
139     '__stack_chk_fail'  => 1,
140     'VDSO32_PRELINK'    => 1,
141     'VDSO32_vsyscall'   => 1,
142     'VDSO32_rt_sigreturn'=>1,
143     'VDSO32_sigreturn'  => 1,
144 );
145 
146 
147 &find(\&linux_objects, '.');    # find the objects and do_nm on them
148 &list_multiply_defined();
149 &resolve_external_references();
150 &list_extra_externals();
151 
152 exit(0);
153 
154 sub linux_objects
155 {
156         # Select objects, ignoring objects which are only created by
157         # merging other objects.  Also ignore all of modules, scripts
158         # and compressed.  Most conglomerate objects are handled by do_nm,
159         # this list only contains the special cases.  These include objects
160         # that are linked from just one other object and objects for which
161         # there is really no permanent source file.
162         my $basename = $_;
163         $_ = $File::Find::name;
164         s:^\./::;
165         if (/.*\.o$/ &&
166                 ! (
167                 m:/built-in.o$:
168                 || m:arch/x86/vdso/:
169                 || m:arch/x86/boot/:
170                 || m:arch/ia64/ia32/ia32.o$:
171                 || m:arch/ia64/kernel/gate-syms.o$:
172                 || m:arch/ia64/lib/__divdi3.o$:
173                 || m:arch/ia64/lib/__divsi3.o$:
174                 || m:arch/ia64/lib/__moddi3.o$:
175                 || m:arch/ia64/lib/__modsi3.o$:
176                 || m:arch/ia64/lib/__udivdi3.o$:
177                 || m:arch/ia64/lib/__udivsi3.o$:
178                 || m:arch/ia64/lib/__umoddi3.o$:
179                 || m:arch/ia64/lib/__umodsi3.o$:
180                 || m:arch/ia64/scripts/check_gas_for_hint.o$:
181                 || m:arch/ia64/sn/kernel/xp.o$:
182                 || m:boot/bbootsect.o$:
183                 || m:boot/bsetup.o$:
184                 || m:/bootsect.o$:
185                 || m:/boot/setup.o$:
186                 || m:/compressed/:
187                 || m:drivers/cdrom/driver.o$:
188                 || m:drivers/char/drm/tdfx_drv.o$:
189                 || m:drivers/ide/ide-detect.o$:
190                 || m:drivers/ide/pci/idedriver-pci.o$:
191                 || m:drivers/media/media.o$:
192                 || m:drivers/scsi/sd_mod.o$:
193                 || m:drivers/video/video.o$:
194                 || m:fs/devpts/devpts.o$:
195                 || m:fs/exportfs/exportfs.o$:
196                 || m:fs/hugetlbfs/hugetlbfs.o$:
197                 || m:fs/msdos/msdos.o$:
198                 || m:fs/nls/nls.o$:
199                 || m:fs/ramfs/ramfs.o$:
200                 || m:fs/romfs/romfs.o$:
201                 || m:fs/vfat/vfat.o$:
202                 || m:init/mounts.o$:
203                 || m:^modules/:
204                 || m:net/netlink/netlink.o$:
205                 || m:net/sched/sched.o$:
206                 || m:/piggy.o$:
207                 || m:^scripts/:
208                 || m:sound/.*/snd-:
209                 || m:^.*/\.tmp_:
210                 || m:^\.tmp_:
211                 || m:/vmlinux-obj.o$:
212                 || m:^tools/:
213                 )
214         ) {
215                 do_nm($basename, $_);
216         }
217         $_ = $basename;         # File::Find expects $_ untouched (undocumented)
218 }
219 
220 sub do_nm
221 {
222         my ($basename, $fullname) = @_;
223         my ($source, $type, $name);
224         if (! -e $basename) {
225                 printf STDERR "$basename does not exist\n";
226                 return;
227         }
228         if ($fullname !~ /\.o$/) {
229                 printf STDERR "$fullname is not an object file\n";
230                 return;
231         }
232         ($source = $basename) =~ s/\.o$//;
233         if (-e "$source.c" || -e "$source.S") {
234                 $source = "$objtree$File::Find::dir/$source";
235         } else {
236                 $source = "$srctree$File::Find::dir/$source";
237         }
238         if (! -e "$source.c" && ! -e "$source.S") {
239                 # No obvious source, exclude the object if it is conglomerate
240                 open(my $objdumpdata, "$objdump $basename|")
241                     or die "$objdump $fullname failed $!\n";
242 
243                 my $comment;
244                 while (<$objdumpdata>) {
245                         chomp();
246                         if (/^In archive/) {
247                                 # Archives are always conglomerate
248                                 $comment = "GCC:GCC:";
249                                 last;
250                         }
251                         next if (! /^[ 0-9a-f]{5,} /);
252                         $comment .= substr($_, 43);
253                 }
254                 close($objdumpdata);
255 
256                 if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) {
257                         printf STDERR "No source file found for $fullname\n";
258                 }
259                 return;
260         }
261         open (my $nmdata, "$nm $basename|")
262             or die "$nm $fullname failed $!\n";
263 
264         my @nmdata;
265         while (<$nmdata>) {
266                 chop;
267                 ($type, $name) = (split(/ +/, $_, 3))[1..2];
268                 # Expected types
269                 # A absolute symbol
270                 # B weak external reference to data that has been resolved
271                 # C global variable, uninitialised
272                 # D global variable, initialised
273                 # G global variable, initialised, small data section
274                 # R global array, initialised
275                 # S global variable, uninitialised, small bss
276                 # T global label/procedure
277                 # U external reference
278                 # W weak external reference to text that has been resolved
279                 # V similar to W, but the value of the weak symbol becomes zero with no error.
280                 # a assembler equate
281                 # b static variable, uninitialised
282                 # d static variable, initialised
283                 # g static variable, initialised, small data section
284                 # r static array, initialised
285                 # s static variable, uninitialised, small bss
286                 # t static label/procedures
287                 # w weak external reference to text that has not been resolved
288                 # v similar to w
289                 # ? undefined type, used a lot by modules
290                 if ($type !~ /^[ABCDGRSTUWVabdgrstwv?]$/) {
291                         printf STDERR "nm output for $fullname contains unknown type '$_'\n";
292                 }
293                 elsif ($name =~ /\./) {
294                         # name with '.' is local static
295                 }
296                 else {
297                         $type = 'R' if ($type eq '?');  # binutils replaced ? with R at one point
298                         # binutils keeps changing the type for exported symbols, force it to R
299                         $type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/);
300                         $name =~ s/_R[a-f0-9]{8}$//;    # module versions adds this
301                         if ($type =~ /[ABCDGRSTWV]/ &&
302                                 $name ne 'init_module' &&
303                                 $name ne 'cleanup_module' &&
304                                 $name ne 'Using_Versions' &&
305                                 $name !~ /^Version_[0-9]+$/ &&
306                                 $name !~ /^__parm_/ &&
307                                 $name !~ /^__kstrtab/ &&
308                                 $name !~ /^__ksymtab/ &&
309                                 $name !~ /^__kcrctab_/ &&
310                                 $name !~ /^__exitcall_/ &&
311                                 $name !~ /^__initcall_/ &&
312                                 $name !~ /^__kdb_initcall_/ &&
313                                 $name !~ /^__kdb_exitcall_/ &&
314                                 $name !~ /^__module_/ &&
315                                 $name !~ /^__mod_/ &&
316                                 $name !~ /^__crc_/ &&
317                                 $name ne '__this_module' &&
318                                 $name ne 'kernel_version') {
319                                 if (!exists($def{$name})) {
320                                         $def{$name} = [];
321                                 }
322                                 push(@{$def{$name}}, $fullname);
323                         }
324                         push(@nmdata, "$type $name");
325                         if ($name =~ /^__ksymtab_/) {
326                                 $name = substr($name, 10);
327                                 if (!exists($ksymtab{$name})) {
328                                         $ksymtab{$name} = [];
329                                 }
330                                 push(@{$ksymtab{$name}}, $fullname);
331                         }
332                 }
333         }
334         close($nmdata);
335 
336         if ($#nmdata < 0) {
337             printf "No nm data for $fullname\n"
338                 unless $nmexception{$fullname};
339             return;
340         }
341         $nmdata{$fullname} = \@nmdata;
342 }
343 
344 sub drop_def
345 {
346         my ($object, $name) = @_;
347         my $nmdata = $nmdata{$object};
348         my ($i, $j);
349         for ($i = 0; $i <= $#{$nmdata}; ++$i) {
350                 if ($name eq (split(' ', $nmdata->[$i], 2))[1]) {
351                         splice(@{$nmdata{$object}}, $i, 1);
352                         my $def = $def{$name};
353                         for ($j = 0; $j < $#{$def{$name}}; ++$j) {
354                                 if ($def{$name}[$j] eq $object) {
355                                         splice(@{$def{$name}}, $j, 1);
356                                 }
357                         }
358                         last;
359                 }
360         }
361 }
362 
363 sub list_multiply_defined
364 {
365         foreach my $name (keys(%def)) {
366                 if ($#{$def{$name}} > 0) {
367                         # Special case for cond_syscall
368                         if ($#{$def{$name}} == 1 &&
369                            ($name =~ /^sys_/ || $name =~ /^compat_sys_/ ||
370                             $name =~ /^sys32_/)) {
371                                 if($def{$name}[0] eq "kernel/sys_ni.o" ||
372                                    $def{$name}[1] eq "kernel/sys_ni.o") {
373                                         &drop_def("kernel/sys_ni.o", $name);
374                                         next;
375                                 }
376                         }
377 
378                         printf "$name is multiply defined in :-\n";
379                         foreach my $module (@{$def{$name}}) {
380                                 printf "\t$module\n";
381                         }
382                 }
383         }
384 }
385 
386 sub resolve_external_references
387 {
388         my ($kstrtab, $ksymtab, $export);
389 
390         printf "\n";
391         foreach my $object (keys(%nmdata)) {
392                 my $nmdata = $nmdata{$object};
393                 for (my $i = 0; $i <= $#{$nmdata}; ++$i) {
394                         my ($type, $name) = split(' ', $nmdata->[$i], 2);
395                         if ($type eq "U" || $type eq "w") {
396                                 if (exists($def{$name}) || exists($ksymtab{$name})) {
397                                         # add the owning object to the nmdata
398                                         $nmdata->[$i] = "$type $name $object";
399                                         # only count as a reference if it is not EXPORT_...
400                                         $kstrtab = "R __kstrtab_$name";
401                                         $ksymtab = "R __ksymtab_$name";
402                                         $export = 0;
403                                         for (my $j = 0; $j <= $#{$nmdata}; ++$j) {
404                                                 if ($nmdata->[$j] eq $kstrtab ||
405                                                     $nmdata->[$j] eq $ksymtab) {
406                                                         $export = 1;
407                                                         last;
408                                                 }
409                                         }
410                                         if ($export) {
411                                                 $export{$name} = "";
412                                         }
413                                         else {
414                                                 $ref{$name} = ""
415                                         }
416                                 }
417                                 elsif ( ! $nameexception{$name}
418                                         && $name !~ /^__sched_text_/
419                                         && $name !~ /^__start_/
420                                         && $name !~ /^__end_/
421                                         && $name !~ /^__stop_/
422                                         && $name !~ /^__scheduling_functions_.*_here/
423                                         && $name !~ /^__.*initcall_/
424                                         && $name !~ /^__.*per_cpu_start/
425                                         && $name !~ /^__.*per_cpu_end/
426                                         && $name !~ /^__alt_instructions/
427                                         && $name !~ /^__setup_/
428                                         && $name !~ /^__mod_timer/
429                                         && $name !~ /^__mod_page_state/
430                                         && $name !~ /^init_module/
431                                         && $name !~ /^cleanup_module/
432                                 ) {
433                                         printf "Cannot resolve ";
434                                         printf "weak " if ($type eq "w");
435                                         printf "reference to $name from $object\n";
436                                 }
437                         }
438                 }
439         }
440 }
441 
442 sub list_extra_externals
443 {
444         my %noref = ();
445 
446         foreach my $name (keys(%def)) {
447                 if (! exists($ref{$name})) {
448                         my @module = @{$def{$name}};
449                         foreach my $module (@module) {
450                                 if (! exists($noref{$module})) {
451                                         $noref{$module} = [];
452                                 }
453                                 push(@{$noref{$module}}, $name);
454                         }
455                 }
456         }
457         if (%noref) {
458                 printf "\nExternally defined symbols with no external references\n";
459                 foreach my $module (sort(keys(%noref))) {
460                         printf "  $module\n";
461                         foreach (sort(@{$noref{$module}})) {
462                             my $export;
463                             if (exists($export{$_})) {
464                                 $export = " (export only)";
465                             } else {
466                                 $export = "";
467                             }
468                             printf "    $_$export\n";
469                         }
470                 }
471         }
472 }

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