GNU Linux-libre 4.19.211-gnu1
[releases.git] / scripts / namespace.pl
1 #!/usr/bin/env perl
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 use warnings;
66 use strict;
67 use File::Find;
68 use File::Spec;
69
70 my $nm = ($ENV{'NM'} || "nm") . " -p";
71 my $objdump = ($ENV{'OBJDUMP'} || "objdump") . " -s -j .comment";
72 my $srctree = File::Spec->curdir();
73 my $objtree = File::Spec->curdir();
74 $srctree = File::Spec->rel2abs($ENV{'srctree'}) if (exists($ENV{'srctree'}));
75 $objtree = File::Spec->rel2abs($ENV{'objtree'}) if (exists($ENV{'objtree'}));
76
77 if ($#ARGV != -1) {
78         print STDERR "usage: $0 takes no parameters\n";
79         die("giving up\n");
80 }
81
82 my %nmdata = ();        # nm data for each object
83 my %def = ();           # all definitions for each name
84 my %ksymtab = ();       # names that appear in __ksymtab_
85 my %ref = ();           # $ref{$name} exists if there is a true external reference to $name
86 my %export = ();        # $export{$name} exists if there is an EXPORT_... of $name
87
88 my %nmexception = (
89     'fs/ext3/bitmap'                    => 1,
90     'fs/ext4/bitmap'                    => 1,
91     'arch/x86/lib/thunk_32'             => 1,
92     'arch/x86/lib/cmpxchg'              => 1,
93     'arch/x86/vdso/vdso32/note'         => 1,
94     'lib/irq_regs'                      => 1,
95     'usr/initramfs_data'                => 1,
96     'drivers/scsi/aic94xx/aic94xx_dump' => 1,
97     'drivers/scsi/libsas/sas_dump'      => 1,
98     'lib/dec_and_lock'                  => 1,
99     'drivers/ide/ide-probe-mini'        => 1,
100     'usr/initramfs_data'                => 1,
101     'drivers/acpi/acpia/exdump'         => 1,
102     'drivers/acpi/acpia/rsdump'         => 1,
103     'drivers/acpi/acpia/nsdumpdv'       => 1,
104     'drivers/acpi/acpia/nsdump'         => 1,
105     'arch/ia64/sn/kernel/sn2/io'        => 1,
106     'arch/ia64/kernel/gate-data'        => 1,
107     'security/capability'               => 1,
108     'fs/ntfs/sysctl'                    => 1,
109     'fs/jfs/jfs_debug'                  => 1,
110 );
111
112 my %nameexception = (
113     'mod_use_count_'     => 1,
114     '__initramfs_end'   => 1,
115     '__initramfs_start' => 1,
116     '_einittext'        => 1,
117     '_sinittext'        => 1,
118     'kallsyms_names'    => 1,
119     'kallsyms_num_syms' => 1,
120     'kallsyms_addresses'=> 1,
121     'kallsyms_offsets'  => 1,
122     'kallsyms_relative_base'=> 1,
123     '__this_module'     => 1,
124     '_etext'            => 1,
125     '_edata'            => 1,
126     '_end'              => 1,
127     '__bss_start'       => 1,
128     '_text'             => 1,
129     '_stext'            => 1,
130     '__gp'              => 1,
131     'ia64_unw_start'    => 1,
132     'ia64_unw_end'      => 1,
133     '__init_begin'      => 1,
134     '__init_end'        => 1,
135     '__bss_stop'        => 1,
136     '__nosave_begin'    => 1,
137     '__nosave_end'      => 1,
138     'pg0'               => 1,
139     'vdso_enabled'      => 1,
140     '__stack_chk_fail'  => 1,
141     'VDSO32_PRELINK'    => 1,
142     'VDSO32_vsyscall'   => 1,
143     'VDSO32_rt_sigreturn'=>1,
144     'VDSO32_sigreturn'  => 1,
145 );
146
147
148 &find(\&linux_objects, '.');    # find the objects and do_nm on them
149 &list_multiply_defined();
150 &resolve_external_references();
151 &list_extra_externals();
152
153 exit(0);
154
155 sub linux_objects
156 {
157         # Select objects, ignoring objects which are only created by
158         # merging other objects.  Also ignore all of modules, scripts
159         # and compressed.  Most conglomerate objects are handled by do_nm,
160         # this list only contains the special cases.  These include objects
161         # that are linked from just one other object and objects for which
162         # there is really no permanent source file.
163         my $basename = $_;
164         $_ = $File::Find::name;
165         s:^\./::;
166         if (/.*\.o$/ &&
167                 ! (
168                 m:/built-in.a$:
169                 || m:arch/x86/vdso/:
170                 || m:arch/x86/boot/:
171                 || m:arch/ia64/ia32/ia32.o$:
172                 || m:arch/ia64/kernel/gate-syms.o$:
173                 || m:arch/ia64/lib/__divdi3.o$:
174                 || m:arch/ia64/lib/__divsi3.o$:
175                 || m:arch/ia64/lib/__moddi3.o$:
176                 || m:arch/ia64/lib/__modsi3.o$:
177                 || m:arch/ia64/lib/__udivdi3.o$:
178                 || m:arch/ia64/lib/__udivsi3.o$:
179                 || m:arch/ia64/lib/__umoddi3.o$:
180                 || m:arch/ia64/lib/__umodsi3.o$:
181                 || m:arch/ia64/scripts/check_gas_for_hint.o$:
182                 || m:arch/ia64/sn/kernel/xp.o$:
183                 || m:boot/bbootsect.o$:
184                 || m:boot/bsetup.o$:
185                 || m:/bootsect.o$:
186                 || m:/boot/setup.o$:
187                 || m:/compressed/:
188                 || m:drivers/cdrom/driver.o$:
189                 || m:drivers/char/drm/tdfx_drv.o$:
190                 || m:drivers/ide/ide-detect.o$:
191                 || m:drivers/ide/pci/idedriver-pci.o$:
192                 || m:drivers/media/media.o$:
193                 || m:drivers/scsi/sd_mod.o$:
194                 || m:drivers/video/video.o$:
195                 || m:fs/devpts/devpts.o$:
196                 || m:fs/exportfs/exportfs.o$:
197                 || m:fs/hugetlbfs/hugetlbfs.o$:
198                 || m:fs/msdos/msdos.o$:
199                 || m:fs/nls/nls.o$:
200                 || m:fs/ramfs/ramfs.o$:
201                 || m:fs/romfs/romfs.o$:
202                 || m:fs/vfat/vfat.o$:
203                 || m:init/mounts.o$:
204                 || m:^modules/:
205                 || m:net/netlink/netlink.o$:
206                 || m:net/sched/sched.o$:
207                 || m:/piggy.o$:
208                 || m:^scripts/:
209                 || m:sound/.*/snd-:
210                 || m:^.*/\.tmp_:
211                 || m:^\.tmp_:
212                 || m:/vmlinux-obj.o$:
213                 || m:^tools/:
214                 )
215         ) {
216                 do_nm($basename, $_);
217         }
218         $_ = $basename;         # File::Find expects $_ untouched (undocumented)
219 }
220
221 sub do_nm
222 {
223         my ($basename, $fullname) = @_;
224         my ($source, $type, $name);
225         if (! -e $basename) {
226                 printf STDERR "$basename does not exist\n";
227                 return;
228         }
229         if ($fullname !~ /\.o$/) {
230                 printf STDERR "$fullname is not an object file\n";
231                 return;
232         }
233         ($source = $basename) =~ s/\.o$//;
234         if (-e "$source.c" || -e "$source.S") {
235                 $source = File::Spec->catfile($objtree, $File::Find::dir, $source)
236         } else {
237                 $source = File::Spec->catfile($srctree, $File::Find::dir, $source)
238         }
239         if (! -e "$source.c" && ! -e "$source.S") {
240                 # No obvious source, exclude the object if it is conglomerate
241                 open(my $objdumpdata, "$objdump $basename|")
242                     or die "$objdump $fullname failed $!\n";
243
244                 my $comment;
245                 while (<$objdumpdata>) {
246                         chomp();
247                         if (/^In archive/) {
248                                 # Archives are always conglomerate
249                                 $comment = "GCC:GCC:";
250                                 last;
251                         }
252                         next if (! /^[ 0-9a-f]{5,} /);
253                         $comment .= substr($_, 43);
254                 }
255                 close($objdumpdata);
256
257                 if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) {
258                         printf STDERR "No source file found for $fullname\n";
259                 }
260                 return;
261         }
262         open (my $nmdata, "$nm $basename|")
263             or die "$nm $fullname failed $!\n";
264
265         my @nmdata;
266         while (<$nmdata>) {
267                 chop;
268                 ($type, $name) = (split(/ +/, $_, 3))[1..2];
269                 # Expected types
270                 # A absolute symbol
271                 # B weak external reference to data that has been resolved
272                 # C global variable, uninitialised
273                 # D global variable, initialised
274                 # G global variable, initialised, small data section
275                 # R global array, initialised
276                 # S global variable, uninitialised, small bss
277                 # T global label/procedure
278                 # U external reference
279                 # W weak external reference to text that has been resolved
280                 # V similar to W, but the value of the weak symbol becomes zero with no error.
281                 # a assembler equate
282                 # b static variable, uninitialised
283                 # d static variable, initialised
284                 # g static variable, initialised, small data section
285                 # r static array, initialised
286                 # s static variable, uninitialised, small bss
287                 # t static label/procedures
288                 # w weak external reference to text that has not been resolved
289                 # v similar to w
290                 # ? undefined type, used a lot by modules
291                 if ($type !~ /^[ABCDGRSTUWVabdgrstwv?]$/) {
292                         printf STDERR "nm output for $fullname contains unknown type '$_'\n";
293                 }
294                 elsif ($name =~ /\./) {
295                         # name with '.' is local static
296                 }
297                 else {
298                         $type = 'R' if ($type eq '?');  # binutils replaced ? with R at one point
299                         # binutils keeps changing the type for exported symbols, force it to R
300                         $type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/);
301                         $name =~ s/_R[a-f0-9]{8}$//;    # module versions adds this
302                         if ($type =~ /[ABCDGRSTWV]/ &&
303                                 $name ne 'init_module' &&
304                                 $name ne 'cleanup_module' &&
305                                 $name ne 'Using_Versions' &&
306                                 $name !~ /^Version_[0-9]+$/ &&
307                                 $name !~ /^__parm_/ &&
308                                 $name !~ /^__kstrtab/ &&
309                                 $name !~ /^__ksymtab/ &&
310                                 $name !~ /^__kcrctab_/ &&
311                                 $name !~ /^__exitcall_/ &&
312                                 $name !~ /^__initcall_/ &&
313                                 $name !~ /^__kdb_initcall_/ &&
314                                 $name !~ /^__kdb_exitcall_/ &&
315                                 $name !~ /^__module_/ &&
316                                 $name !~ /^__mod_/ &&
317                                 $name !~ /^__crc_/ &&
318                                 $name ne '__this_module' &&
319                                 $name ne 'kernel_version') {
320                                 if (!exists($def{$name})) {
321                                         $def{$name} = [];
322                                 }
323                                 push(@{$def{$name}}, $fullname);
324                         }
325                         push(@nmdata, "$type $name");
326                         if ($name =~ /^__ksymtab_/) {
327                                 $name = substr($name, 10);
328                                 if (!exists($ksymtab{$name})) {
329                                         $ksymtab{$name} = [];
330                                 }
331                                 push(@{$ksymtab{$name}}, $fullname);
332                         }
333                 }
334         }
335         close($nmdata);
336
337         if ($#nmdata < 0) {
338             printf "No nm data for $fullname\n"
339                 unless $nmexception{$fullname};
340             return;
341         }
342         $nmdata{$fullname} = \@nmdata;
343 }
344
345 sub drop_def
346 {
347         my ($object, $name) = @_;
348         my $nmdata = $nmdata{$object};
349         my ($i, $j);
350         for ($i = 0; $i <= $#{$nmdata}; ++$i) {
351                 if ($name eq (split(' ', $nmdata->[$i], 2))[1]) {
352                         splice(@{$nmdata{$object}}, $i, 1);
353                         my $def = $def{$name};
354                         for ($j = 0; $j < $#{$def{$name}}; ++$j) {
355                                 if ($def{$name}[$j] eq $object) {
356                                         splice(@{$def{$name}}, $j, 1);
357                                 }
358                         }
359                         last;
360                 }
361         }
362 }
363
364 sub list_multiply_defined
365 {
366         foreach my $name (keys(%def)) {
367                 if ($#{$def{$name}} > 0) {
368                         # Special case for cond_syscall
369                         if ($#{$def{$name}} == 1 &&
370                            ($name =~ /^sys_/ || $name =~ /^compat_sys_/ ||
371                             $name =~ /^sys32_/)) {
372                                 if($def{$name}[0] eq "kernel/sys_ni.o" ||
373                                    $def{$name}[1] eq "kernel/sys_ni.o") {
374                                         &drop_def("kernel/sys_ni.o", $name);
375                                         next;
376                                 }
377                         }
378
379                         printf "$name is multiply defined in :-\n";
380                         foreach my $module (@{$def{$name}}) {
381                                 printf "\t$module\n";
382                         }
383                 }
384         }
385 }
386
387 sub resolve_external_references
388 {
389         my ($kstrtab, $ksymtab, $export);
390
391         printf "\n";
392         foreach my $object (keys(%nmdata)) {
393                 my $nmdata = $nmdata{$object};
394                 for (my $i = 0; $i <= $#{$nmdata}; ++$i) {
395                         my ($type, $name) = split(' ', $nmdata->[$i], 2);
396                         if ($type eq "U" || $type eq "w") {
397                                 if (exists($def{$name}) || exists($ksymtab{$name})) {
398                                         # add the owning object to the nmdata
399                                         $nmdata->[$i] = "$type $name $object";
400                                         # only count as a reference if it is not EXPORT_...
401                                         $kstrtab = "R __kstrtab_$name";
402                                         $ksymtab = "R __ksymtab_$name";
403                                         $export = 0;
404                                         for (my $j = 0; $j <= $#{$nmdata}; ++$j) {
405                                                 if ($nmdata->[$j] eq $kstrtab ||
406                                                     $nmdata->[$j] eq $ksymtab) {
407                                                         $export = 1;
408                                                         last;
409                                                 }
410                                         }
411                                         if ($export) {
412                                                 $export{$name} = "";
413                                         }
414                                         else {
415                                                 $ref{$name} = ""
416                                         }
417                                 }
418                                 elsif ( ! $nameexception{$name}
419                                         && $name !~ /^__sched_text_/
420                                         && $name !~ /^__start_/
421                                         && $name !~ /^__end_/
422                                         && $name !~ /^__stop_/
423                                         && $name !~ /^__scheduling_functions_.*_here/
424                                         && $name !~ /^__.*initcall_/
425                                         && $name !~ /^__.*per_cpu_start/
426                                         && $name !~ /^__.*per_cpu_end/
427                                         && $name !~ /^__alt_instructions/
428                                         && $name !~ /^__setup_/
429                                         && $name !~ /^__mod_timer/
430                                         && $name !~ /^__mod_page_state/
431                                         && $name !~ /^init_module/
432                                         && $name !~ /^cleanup_module/
433                                 ) {
434                                         printf "Cannot resolve ";
435                                         printf "weak " if ($type eq "w");
436                                         printf "reference to $name from $object\n";
437                                 }
438                         }
439                 }
440         }
441 }
442
443 sub list_extra_externals
444 {
445         my %noref = ();
446
447         foreach my $name (keys(%def)) {
448                 if (! exists($ref{$name})) {
449                         my @module = @{$def{$name}};
450                         foreach my $module (@module) {
451                                 if (! exists($noref{$module})) {
452                                         $noref{$module} = [];
453                                 }
454                                 push(@{$noref{$module}}, $name);
455                         }
456                 }
457         }
458         if (%noref) {
459                 printf "\nExternally defined symbols with no external references\n";
460                 foreach my $module (sort(keys(%noref))) {
461                         printf "  $module\n";
462                         foreach (sort(@{$noref{$module}})) {
463                             my $export;
464                             if (exists($export{$_})) {
465                                 $export = " (export only)";
466                             } else {
467                                 $export = "";
468                             }
469                             printf "    $_$export\n";
470                         }
471                 }
472         }
473 }