Add support for the C variable in the coccicheck script
[linux-2.6.git] / 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 &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$:
108                 || m:arch/x86/kernel/vsyscall-syms.o$:
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                 open(my $objdumpdata, "$objdump $basename|")
179                     or die "$objdump $fullname failed $!\n";
180
181                 my $comment;
182                 while (<$objdumpdata>) {
183                         chomp();
184                         if (/^In archive/) {
185                                 # Archives are always conglomerate
186                                 $comment = "GCC:GCC:";
187                                 last;
188                         }
189                         next if (! /^[ 0-9a-f]{5,} /);
190                         $comment .= substr($_, 43);
191                 }
192                 close($objdumpdata);
193
194                 if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) {
195                         printf STDERR "No source file found for $fullname\n";
196                 }
197                 return;
198         }
199         open (my $nmdata, "$nm $basename|")
200             or die "$nm $fullname failed $!\n";
201
202         my @nmdata;
203         while (<$nmdata>) {
204                 chop;
205                 ($type, $name) = (split(/ +/, $_, 3))[1..2];
206                 # Expected types
207                 # A absolute symbol
208                 # B weak external reference to data that has been resolved
209                 # C global variable, uninitialised
210                 # D global variable, initialised
211                 # G global variable, initialised, small data section
212                 # R global array, initialised
213                 # S global variable, uninitialised, small bss
214                 # T global label/procedure
215                 # U external reference
216                 # W weak external reference to text that has been resolved
217                 # a assembler equate
218                 # b static variable, uninitialised
219                 # d static variable, initialised
220                 # g static variable, initialised, small data section
221                 # r static array, initialised
222                 # s static variable, uninitialised, small bss
223                 # t static label/procedures
224                 # w weak external reference to text that has not been resolved
225                 # ? undefined type, used a lot by modules
226                 if ($type !~ /^[ABCDGRSTUWabdgrstw?]$/) {
227                         printf STDERR "nm output for $fullname contains unknown type '$_'\n";
228                 }
229                 elsif ($name =~ /\./) {
230                         # name with '.' is local static
231                 }
232                 else {
233                         $type = 'R' if ($type eq '?');  # binutils replaced ? with R at one point
234                         # binutils keeps changing the type for exported symbols, force it to R
235                         $type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/);
236                         $name =~ s/_R[a-f0-9]{8}$//;    # module versions adds this
237                         if ($type =~ /[ABCDGRSTW]/ &&
238                                 $name ne 'init_module' &&
239                                 $name ne 'cleanup_module' &&
240                                 $name ne 'Using_Versions' &&
241                                 $name !~ /^Version_[0-9]+$/ &&
242                                 $name !~ /^__parm_/ &&
243                                 $name !~ /^__kstrtab/ &&
244                                 $name !~ /^__ksymtab/ &&
245                                 $name !~ /^__kcrctab_/ &&
246                                 $name !~ /^__exitcall_/ &&
247                                 $name !~ /^__initcall_/ &&
248                                 $name !~ /^__kdb_initcall_/ &&
249                                 $name !~ /^__kdb_exitcall_/ &&
250                                 $name !~ /^__module_/ &&
251                                 $name !~ /^__mod_/ &&
252                                 $name !~ /^__crc_/ &&
253                                 $name ne '__this_module' &&
254                                 $name ne 'kernel_version') {
255                                 if (!exists($def{$name})) {
256                                         $def{$name} = [];
257                                 }
258                                 push(@{$def{$name}}, $fullname);
259                         }
260                         push(@nmdata, "$type $name");
261                         if ($name =~ /^__ksymtab_/) {
262                                 $name = substr($name, 10);
263                                 if (!exists($ksymtab{$name})) {
264                                         $ksymtab{$name} = [];
265                                 }
266                                 push(@{$ksymtab{$name}}, $fullname);
267                         }
268                 }
269         }
270         close($nmdata);
271
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         foreach my $name (keys(%def)) {
320                 if ($#{$def{$name}} > 0) {
321                         # Special case for cond_syscall
322                         if ($#{$def{$name}} == 1 && $name =~ /^sys_/ &&
323                             ($def{$name}[0] eq "kernel/sys.o" ||
324                              $def{$name}[1] eq "kernel/sys.o")) {
325                                 &drop_def("kernel/sys.o", $name);
326                                 next;
327                         }
328                         # Special case for i386 entry code
329                         if ($#{$def{$name}} == 1 && $name =~ /^__kernel_/ &&
330                             $def{$name}[0] eq "arch/x86/kernel/vsyscall-int80_32.o" &&
331                             $def{$name}[1] eq "arch/x86/kernel/vsyscall-sysenter_32.o") {
332                                 &drop_def("arch/x86/kernel/vsyscall-sysenter_32.o", $name);
333                                 next;
334                         }
335
336                         printf "$name is multiply defined in :-\n";
337                         foreach my $module (@{$def{$name}}) {
338                                 printf "\t$module\n";
339                         }
340                 }
341         }
342 }
343
344 sub resolve_external_references
345 {
346         my ($kstrtab, $ksymtab, $export);
347
348         printf "\n";
349         foreach my $object (keys(%nmdata)) {
350                 my $nmdata = $nmdata{$object};
351                 for (my $i = 0; $i <= $#{$nmdata}; ++$i) {
352                         my ($type, $name) = split(' ', $nmdata->[$i], 2);
353                         if ($type eq "U" || $type eq "w") {
354                                 if (exists($def{$name}) || exists($ksymtab{$name})) {
355                                         # add the owning object to the nmdata
356                                         $nmdata->[$i] = "$type $name $object";
357                                         # only count as a reference if it is not EXPORT_...
358                                         $kstrtab = "R __kstrtab_$name";
359                                         $ksymtab = "R __ksymtab_$name";
360                                         $export = 0;
361                                         for (my $j = 0; $j <= $#{$nmdata}; ++$j) {
362                                                 if ($nmdata->[$j] eq $kstrtab ||
363                                                     $nmdata->[$j] eq $ksymtab) {
364                                                         $export = 1;
365                                                         last;
366                                                 }
367                                         }
368                                         if ($export) {
369                                                 $export{$name} = "";
370                                         }
371                                         else {
372                                                 $ref{$name} = ""
373                                         }
374                                 }
375                                 elsif (    $name ne "mod_use_count_"
376                                         && $name ne "__initramfs_end"
377                                         && $name ne "__initramfs_start"
378                                         && $name ne "_einittext"
379                                         && $name ne "_sinittext"
380                                         && $name ne "kallsyms_names"
381                                         && $name ne "kallsyms_num_syms"
382                                         && $name ne "kallsyms_addresses"
383                                         && $name ne "__this_module"
384                                         && $name ne "_etext"
385                                         && $name ne "_edata"
386                                         && $name ne "_end"
387                                         && $name ne "__bss_start"
388                                         && $name ne "_text"
389                                         && $name ne "_stext"
390                                         && $name ne "__gp"
391                                         && $name ne "ia64_unw_start"
392                                         && $name ne "ia64_unw_end"
393                                         && $name ne "__init_begin"
394                                         && $name ne "__init_end"
395                                         && $name ne "__bss_stop"
396                                         && $name ne "__nosave_begin"
397                                         && $name ne "__nosave_end"
398                                         && $name ne "pg0"
399                                         && $name ne "__module_text_address"
400                                         && $name !~ /^__sched_text_/
401                                         && $name !~ /^__start_/
402                                         && $name !~ /^__end_/
403                                         && $name !~ /^__stop_/
404                                         && $name !~ /^__scheduling_functions_.*_here/
405                                         && $name !~ /^__.*initcall_/
406                                         && $name !~ /^__.*per_cpu_start/
407                                         && $name !~ /^__.*per_cpu_end/
408                                         && $name !~ /^__alt_instructions/
409                                         && $name !~ /^__setup_/
410                                         && $name !~ /^jiffies/
411                                         && $name !~ /^__mod_timer/
412                                         && $name !~ /^__mod_page_state/
413                                         && $name !~ /^init_module/
414                                         && $name !~ /^cleanup_module/
415                                 ) {
416                                         printf "Cannot resolve ";
417                                         printf "weak " if ($type eq "w");
418                                         printf "reference to $name from $object\n";
419                                 }
420                         }
421                 }
422         }
423 }
424
425 sub list_extra_externals
426 {
427         my %noref = ();
428
429         foreach my $name (keys(%def)) {
430                 if (! exists($ref{$name})) {
431                         my @module = @{$def{$name}};
432                         foreach my $module (@module) {
433                                 if (! exists($noref{$module})) {
434                                         $noref{$module} = [];
435                                 }
436                                 push(@{$noref{$module}}, $name);
437                         }
438                 }
439         }
440         if (%noref) {
441                 printf "\nExternally defined symbols with no external references\n";
442                 foreach my $module (sort(keys(%noref))) {
443                         printf "  $module\n";
444                         foreach (sort(@{$noref{$module}})) {
445                             my $export;
446                             if (exists($export{$_})) {
447                                 $export = " (export only)";
448                             } else {
449                                 $export = "";
450                             }
451                             printf "    $_$export\n";
452                         }
453                 }
454         }
455 }