Root/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
65require 5; # at least perl 5
66use strict;
67use File::Find;
68
69my $nm = ($ENV{'NM'} || "nm") . " -p";
70my $objdump = ($ENV{'OBJDUMP'} || "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
87my %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
111my %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    '__this_module' => 1,
121    '_etext' => 1,
122    '_edata' => 1,
123    '_end' => 1,
124    '__bss_start' => 1,
125    '_text' => 1,
126    '_stext' => 1,
127    '__gp' => 1,
128    'ia64_unw_start' => 1,
129    'ia64_unw_end' => 1,
130    '__init_begin' => 1,
131    '__init_end' => 1,
132    '__bss_stop' => 1,
133    '__nosave_begin' => 1,
134    '__nosave_end' => 1,
135    'pg0' => 1,
136    'vdso_enabled' => 1,
137    '__stack_chk_fail' => 1,
138    'VDSO32_PRELINK' => 1,
139    'VDSO32_vsyscall' => 1,
140    'VDSO32_rt_sigreturn'=>1,
141    'VDSO32_sigreturn' => 1,
142);
143
144
145&find(\&linux_objects, '.'); # find the objects and do_nm on them
146&list_multiply_defined();
147&resolve_external_references();
148&list_extra_externals();
149
150exit(0);
151
152sub linux_objects
153{
154    # Select objects, ignoring objects which are only created by
155    # merging other objects. Also ignore all of modules, scripts
156    # and compressed. Most conglomerate objects are handled by do_nm,
157    # this list only contains the special cases. These include objects
158    # that are linked from just one other object and objects for which
159    # there is really no permanent source file.
160    my $basename = $_;
161    $_ = $File::Find::name;
162    s:^\./::;
163    if (/.*\.o$/ &&
164        ! (
165        m:/built-in.o$:
166        || m:arch/x86/vdso/:
167        || m:arch/x86/boot/:
168        || m:arch/ia64/ia32/ia32.o$:
169        || m:arch/ia64/kernel/gate-syms.o$:
170        || m:arch/ia64/lib/__divdi3.o$:
171        || m:arch/ia64/lib/__divsi3.o$:
172        || m:arch/ia64/lib/__moddi3.o$:
173        || m:arch/ia64/lib/__modsi3.o$:
174        || m:arch/ia64/lib/__udivdi3.o$:
175        || m:arch/ia64/lib/__udivsi3.o$:
176        || m:arch/ia64/lib/__umoddi3.o$:
177        || m:arch/ia64/lib/__umodsi3.o$:
178        || m:arch/ia64/scripts/check_gas_for_hint.o$:
179        || m:arch/ia64/sn/kernel/xp.o$:
180        || m:boot/bbootsect.o$:
181        || m:boot/bsetup.o$:
182        || m:/bootsect.o$:
183        || m:/boot/setup.o$:
184        || m:/compressed/:
185        || m:drivers/cdrom/driver.o$:
186        || m:drivers/char/drm/tdfx_drv.o$:
187        || m:drivers/ide/ide-detect.o$:
188        || m:drivers/ide/pci/idedriver-pci.o$:
189        || m:drivers/media/media.o$:
190        || m:drivers/scsi/sd_mod.o$:
191        || m:drivers/video/video.o$:
192        || m:fs/devpts/devpts.o$:
193        || m:fs/exportfs/exportfs.o$:
194        || m:fs/hugetlbfs/hugetlbfs.o$:
195        || m:fs/msdos/msdos.o$:
196        || m:fs/nls/nls.o$:
197        || m:fs/ramfs/ramfs.o$:
198        || m:fs/romfs/romfs.o$:
199        || m:fs/vfat/vfat.o$:
200        || m:init/mounts.o$:
201        || m:^modules/:
202        || m:net/netlink/netlink.o$:
203        || m:net/sched/sched.o$:
204        || m:/piggy.o$:
205        || m:^scripts/:
206        || m:sound/.*/snd-:
207        || m:^.*/\.tmp_:
208        || m:^\.tmp_:
209        || m:/vmlinux-obj.o$:
210        || m:^tools/:
211        )
212    ) {
213        do_nm($basename, $_);
214    }
215    $_ = $basename; # File::Find expects $_ untouched (undocumented)
216}
217
218sub do_nm
219{
220    my ($basename, $fullname) = @_;
221    my ($source, $type, $name);
222    if (! -e $basename) {
223        printf STDERR "$basename does not exist\n";
224        return;
225    }
226    if ($fullname !~ /\.o$/) {
227        printf STDERR "$fullname is not an object file\n";
228        return;
229    }
230    ($source = $basename) =~ s/\.o$//;
231    if (-e "$source.c" || -e "$source.S") {
232        $source = "$objtree$File::Find::dir/$source";
233    } else {
234        $source = "$srctree$File::Find::dir/$source";
235    }
236    if (! -e "$source.c" && ! -e "$source.S") {
237        # No obvious source, exclude the object if it is conglomerate
238            open(my $objdumpdata, "$objdump $basename|")
239            or die "$objdump $fullname failed $!\n";
240
241        my $comment;
242        while (<$objdumpdata>) {
243            chomp();
244            if (/^In archive/) {
245                # Archives are always conglomerate
246                $comment = "GCC:GCC:";
247                last;
248            }
249            next if (! /^[ 0-9a-f]{5,} /);
250            $comment .= substr($_, 43);
251        }
252        close($objdumpdata);
253
254        if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) {
255            printf STDERR "No source file found for $fullname\n";
256        }
257        return;
258    }
259    open (my $nmdata, "$nm $basename|")
260        or die "$nm $fullname failed $!\n";
261
262    my @nmdata;
263    while (<$nmdata>) {
264        chop;
265        ($type, $name) = (split(/ +/, $_, 3))[1..2];
266        # Expected types
267        # A absolute symbol
268        # B weak external reference to data that has been resolved
269        # C global variable, uninitialised
270        # D global variable, initialised
271        # G global variable, initialised, small data section
272        # R global array, initialised
273        # S global variable, uninitialised, small bss
274        # T global label/procedure
275        # U external reference
276        # W weak external reference to text that has been resolved
277        # V similar to W, but the value of the weak symbol becomes zero with no error.
278        # a assembler equate
279        # b static variable, uninitialised
280        # d static variable, initialised
281        # g static variable, initialised, small data section
282        # r static array, initialised
283        # s static variable, uninitialised, small bss
284        # t static label/procedures
285        # w weak external reference to text that has not been resolved
286        # v similar to w
287        # ? undefined type, used a lot by modules
288        if ($type !~ /^[ABCDGRSTUWVabdgrstwv?]$/) {
289            printf STDERR "nm output for $fullname contains unknown type '$_'\n";
290        }
291        elsif ($name =~ /\./) {
292            # name with '.' is local static
293        }
294        else {
295            $type = 'R' if ($type eq '?'); # binutils replaced ? with R at one point
296            # binutils keeps changing the type for exported symbols, force it to R
297            $type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/);
298            $name =~ s/_R[a-f0-9]{8}$//; # module versions adds this
299            if ($type =~ /[ABCDGRSTWV]/ &&
300                $name ne 'init_module' &&
301                $name ne 'cleanup_module' &&
302                $name ne 'Using_Versions' &&
303                $name !~ /^Version_[0-9]+$/ &&
304                $name !~ /^__parm_/ &&
305                $name !~ /^__kstrtab/ &&
306                $name !~ /^__ksymtab/ &&
307                $name !~ /^__kcrctab_/ &&
308                $name !~ /^__exitcall_/ &&
309                $name !~ /^__initcall_/ &&
310                $name !~ /^__kdb_initcall_/ &&
311                $name !~ /^__kdb_exitcall_/ &&
312                $name !~ /^__module_/ &&
313                $name !~ /^__mod_/ &&
314                $name !~ /^__crc_/ &&
315                $name ne '__this_module' &&
316                $name ne 'kernel_version') {
317                if (!exists($def{$name})) {
318                    $def{$name} = [];
319                }
320                push(@{$def{$name}}, $fullname);
321            }
322            push(@nmdata, "$type $name");
323            if ($name =~ /^__ksymtab_/) {
324                $name = substr($name, 10);
325                if (!exists($ksymtab{$name})) {
326                    $ksymtab{$name} = [];
327                }
328                push(@{$ksymtab{$name}}, $fullname);
329            }
330        }
331    }
332    close($nmdata);
333
334    if ($#nmdata < 0) {
335        printf "No nm data for $fullname\n"
336        unless $nmexception{$fullname};
337        return;
338    }
339    $nmdata{$fullname} = \@nmdata;
340}
341
342sub drop_def
343{
344    my ($object, $name) = @_;
345    my $nmdata = $nmdata{$object};
346    my ($i, $j);
347    for ($i = 0; $i <= $#{$nmdata}; ++$i) {
348        if ($name eq (split(' ', $nmdata->[$i], 2))[1]) {
349            splice(@{$nmdata{$object}}, $i, 1);
350            my $def = $def{$name};
351            for ($j = 0; $j < $#{$def{$name}}; ++$j) {
352                if ($def{$name}[$j] eq $object) {
353                    splice(@{$def{$name}}, $j, 1);
354                }
355            }
356            last;
357        }
358    }
359}
360
361sub list_multiply_defined
362{
363    foreach my $name (keys(%def)) {
364        if ($#{$def{$name}} > 0) {
365            # Special case for cond_syscall
366            if ($#{$def{$name}} == 1 &&
367               ($name =~ /^sys_/ || $name =~ /^compat_sys_/ ||
368                $name =~ /^sys32_/)) {
369                if($def{$name}[0] eq "kernel/sys_ni.o" ||
370                   $def{$name}[1] eq "kernel/sys_ni.o") {
371                    &drop_def("kernel/sys_ni.o", $name);
372                    next;
373                }
374            }
375
376            printf "$name is multiply defined in :-\n";
377            foreach my $module (@{$def{$name}}) {
378                printf "\t$module\n";
379            }
380        }
381    }
382}
383
384sub resolve_external_references
385{
386    my ($kstrtab, $ksymtab, $export);
387
388    printf "\n";
389    foreach my $object (keys(%nmdata)) {
390        my $nmdata = $nmdata{$object};
391        for (my $i = 0; $i <= $#{$nmdata}; ++$i) {
392            my ($type, $name) = split(' ', $nmdata->[$i], 2);
393            if ($type eq "U" || $type eq "w") {
394                if (exists($def{$name}) || exists($ksymtab{$name})) {
395                    # add the owning object to the nmdata
396                    $nmdata->[$i] = "$type $name $object";
397                    # only count as a reference if it is not EXPORT_...
398                    $kstrtab = "R __kstrtab_$name";
399                    $ksymtab = "R __ksymtab_$name";
400                    $export = 0;
401                    for (my $j = 0; $j <= $#{$nmdata}; ++$j) {
402                        if ($nmdata->[$j] eq $kstrtab ||
403                            $nmdata->[$j] eq $ksymtab) {
404                            $export = 1;
405                            last;
406                        }
407                    }
408                    if ($export) {
409                        $export{$name} = "";
410                    }
411                    else {
412                        $ref{$name} = ""
413                    }
414                }
415                elsif ( ! $nameexception{$name}
416                    && $name !~ /^__sched_text_/
417                    && $name !~ /^__start_/
418                    && $name !~ /^__end_/
419                    && $name !~ /^__stop_/
420                    && $name !~ /^__scheduling_functions_.*_here/
421                    && $name !~ /^__.*initcall_/
422                    && $name !~ /^__.*per_cpu_start/
423                    && $name !~ /^__.*per_cpu_end/
424                    && $name !~ /^__alt_instructions/
425                    && $name !~ /^__setup_/
426                    && $name !~ /^__mod_timer/
427                    && $name !~ /^__mod_page_state/
428                    && $name !~ /^init_module/
429                    && $name !~ /^cleanup_module/
430                ) {
431                    printf "Cannot resolve ";
432                    printf "weak " if ($type eq "w");
433                    printf "reference to $name from $object\n";
434                }
435            }
436        }
437    }
438}
439
440sub list_extra_externals
441{
442    my %noref = ();
443
444    foreach my $name (keys(%def)) {
445        if (! exists($ref{$name})) {
446            my @module = @{$def{$name}};
447            foreach my $module (@module) {
448                if (! exists($noref{$module})) {
449                    $noref{$module} = [];
450                }
451                push(@{$noref{$module}}, $name);
452            }
453        }
454    }
455    if (%noref) {
456        printf "\nExternally defined symbols with no external references\n";
457        foreach my $module (sort(keys(%noref))) {
458            printf " $module\n";
459            foreach (sort(@{$noref{$module}})) {
460                my $export;
461                if (exists($export{$_})) {
462                $export = " (export only)";
463                } else {
464                $export = "";
465                }
466                printf " $_$export\n";
467            }
468        }
469    }
470}
471

Archive Download this file



interactive