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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
65require 5; # at least perl 5
66use strict;
67use File::Find;
68
69my $nm = "/usr/bin/nm -p";
70my $objdump = "/usr/bin/objdump -s -j .comment";
71my $srctree = "";
72my $objtree = "";
73$srctree = "$ENV{'srctree'}/" if (exists($ENV{'srctree'}));
74$objtree = "$ENV{'objtree'}/" if (exists($ENV{'objtree'}));
75
76if ($#ARGV != -1) {
77 print STDERR "usage: $0 takes no parameters\n";
78 die("giving up\n");
79}
80
81my %nmdata = (); # nm data for each object
82my %def = (); # all definitions for each name
83my %ksymtab = (); # names that appear in __ksymtab_
84my %ref = (); # $ref{$name} exists if there is a true external reference to $name
85my %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
92exit(0);
93
94sub 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 $_ untouched (undocumented)
156}
157
158sub do_nm
159{
160 my ($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
298sub 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}}, $j, 1);
310 }
311 }
312 last;
313 }
314 }
315}
316
317sub list_multiply_defined
318{
319 my ($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
344sub 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 $object\n";
418 }
419 }
420 }
421 }
422}
423
424sub list_extra_externals
425{
426 my %noref = ();
427 my ($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}
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