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
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$:
108        || m:arch/x86/kernel/vsyscall-syms.o$:
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 $_ untouched (undocumented)
156}
157
158sub do_nm
159{
160    my ($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/x86/kernel/vsyscall-int80_32.o" &&
332                $def{$name}[1] eq "arch/x86/kernel/vsyscall-sysenter_32.o") {
333                &drop_def("arch/x86/kernel/vsyscall-sysenter_32.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}
455

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