#!/usr/bin/env perl
#
# namespace.pl. Mon Aug 30 2004
#
# Perform a name space analysis on the linux kernel.
#
# Copyright Keith Owens <kaos@ocs.com.au>. GPL.
#
# Invoke by changing directory to the top of the kernel object
# tree then namespace.pl, no parameters.
#
# Tuned for 2.1.x kernels with the new module handling, it will
# work with 2.0 kernels as well.
#
# Last change 2.6.9-rc1, adding support for separate source and object
# trees.
#
# The source must be compiled/assembled first, the object files
# are the primary input to this script. Incomplete or missing
# objects will result in a flawed analysis. Compile both vmlinux
# and modules.
#
# Even with complete objects, treat the result of the analysis
# with caution. Some external references are only used by
# certain architectures, others with certain combinations of
# configuration parameters. Ideally the source should include
# something like
#
# #ifndef CONFIG_...
# static
# #endif
# symbol_definition;
#
# so the symbols are defined as static unless a particular
# CONFIG_... requires it to be external.
#
# A symbol that is suffixed with '(export only)' has these properties
#
# * It is global.
# * It is marked EXPORT_SYMBOL or EXPORT_SYMBOL_GPL, either in the same
# source file or a different source file.
# * Given the current .config, nothing uses the symbol.
#
# The symbol is a candidate for conversion to static, plus removal of the
# export. But be careful that a different .config might use the symbol.
#
#
# Name space analysis and cleanup is an iterative process. You cannot
# expect to find all the problems in a single pass.
#
# * Identify possibly unnecessary global declarations, verify that they
# really are unnecessary and change them to static.
# * Compile and fix up gcc warnings about static, removing dead symbols
# as necessary.
# * make clean and rebuild with different configs (especially
# CONFIG_MODULES=n) to see which symbols are being defined when the
# config does not require them. These symbols bloat the kernel object
# for no good reason, which is frustrating for embedded systems.
# * Wrap config sensitive symbols in #ifdef CONFIG_foo, as long as the
# code does not get too ugly.
# * Repeat the name space analysis until you can live with with the
# result.
#
use warnings;
use strict;
use File::Find;
my $nm = ($ENV{'NM'} || "nm") . " -p";
my $objdump = ($ENV{'OBJDUMP'} || "objdump") . " -s -j .comment";
my $srctree = "";
my $objtree = "";
$srctree = "$ENV{'srctree'}/" if (exists($ENV{'srctree'}));
$objtree = "$ENV{'objtree'}/" if (exists($ENV{'objtree'}));
if ($#ARGV != -1) {
print STDERR "usage: $0 takes no parameters\n";
die("giving up\n");
}
my %nmdata = (); # nm data for each object
my %def = (); # all definitions for each name
my %ksymtab = (); # names that appear in __ksymtab_
my %ref = (); # $ref{$name} exists if there is a true external reference to $name
my %export = (); # $export{$name} exists if there is an EXPORT_... of $name
my %nmexception = (
'fs/ext3/bitmap' => 1,
'fs/ext4/bitmap' => 1,
'arch/x86/lib/thunk_32' => 1,
'arch/x86/lib/cmpxchg' => 1,
'arch/x86/vdso/vdso32/note' => 1,
'lib/irq_regs' => 1,
'usr/initramfs_data' => 1,
'drivers/scsi/aic94xx/aic94xx_dump' => 1,
'drivers/scsi/libsas/sas_dump' => 1,
'lib/dec_and_lock' => 1,
'drivers/ide/ide-probe-mini' => 1,
'usr/initramfs_data' => 1,
'drivers/acpi/acpia/exdump' => 1,
'drivers/acpi/acpia/rsdump' => 1,
'drivers/acpi/acpia/nsdumpdv' => 1,
'drivers/acpi/acpia/nsdump' => 1,
'arch/ia64/sn/kernel/sn2/io' => 1,
'arch/ia64/kernel/gate-data' => 1,
'security/capability' => 1,
'fs/ntfs/sysctl' => 1,
'fs/jfs/jfs_debug' => 1,
);
my %nameexception = (
'mod_use_count_' => 1,
'__initramfs_end' => 1,
'__initramfs_start' => 1,
'_einittext' => 1,
'_sinittext' => 1,
'kallsyms_names' => 1,
'kallsyms_num_syms' => 1,
'kallsyms_addresses'=> 1,
'kallsyms_offsets' => 1,
'kallsyms_relative_base'=> 1,
'__this_module' => 1,
'_etext' => 1,
'_edata' => 1,
'_end' => 1,
'__bss_start' => 1,
'_text' => 1,
'_stext' => 1,
'__gp' => 1,
'ia64_unw_start' => 1,
'ia64_unw_end' => 1,
'__init_begin' => 1,
'__init_end' => 1,
'__bss_stop' => 1,
'__nosave_begin' => 1,
'__nosave_end' => 1,
'pg0' => 1,
'vdso_enabled' => 1,
'__stack_chk_fail' => 1,
'VDSO32_PRELINK' => 1,
'VDSO32_vsyscall' => 1,
'VDSO32_rt_sigreturn'=>1,
'VDSO32_sigreturn' => 1,
);
&find(\&linux_objects, '.'); # find the objects and do_nm on them
&list_multiply_defined();
&resolve_external_references();
&list_extra_externals();
exit(0);
sub linux_objects
{
# Select objects, ignoring objects which are only created by
# merging other objects. Also ignore all of modules, scripts
# and compressed. Most conglomerate objects are handled by do_nm,
# this list only contains the special cases. These include objects
# that are linked from just one other object and objects for which
# there is really no permanent source file.
my $basename = $_;
$_ = $File::Find::name;
s:^\./::;
if (/.*\.o$/ &&
! (
m:/built-in.a$:
|| m:arch/x86/vdso/:
|| m:arch/x86/boot/:
|| m:arch/ia64/ia32/ia32.o$:
|| m:arch/ia64/kernel/gate-syms.o$:
|| m:arch/ia64/lib/__divdi3.o$:
|| m:arch/ia64/lib/__divsi3.o$:
|| m:arch/ia64/lib/__moddi3.o$:
|| m:arch/ia64/lib/__modsi3.o$:
|| m:arch/ia64/lib/__udivdi3.o$:
|| m:arch/ia64/lib/__udivsi3.o$:
|| m:arch/ia64/lib/__umoddi3.o$:
|| m:arch/ia64/lib/__umodsi3.o$:
|| m:arch/ia64/scripts/check_gas_for_hint.o$:
|| m:arch/ia64/sn/kernel/xp.o$:
|| m:boot/bbootsect.o$:
|| m:boot/bsetup.o$:
|| m:/bootsect.o$:
|| m:/boot/setup.o$:
|| m:/compressed/:
|| m:drivers/cdrom/driver.o$:
|| m:drivers/char/drm/tdfx_drv.o$:
|| m:drivers/ide/ide-detect.o$:
|| m:drivers/ide/pci/idedriver-pci.o$:
|| m:drivers/media/media.o$:
|| m:drivers/scsi/sd_mod.o$:
|| m:drivers/video/video.o$:
|| m:fs/devpts/devpts.o$:
|| m:fs/exportfs/exportfs.o$:
|| m:fs/hugetlbfs/hugetlbfs.o$:
|| m:fs/msdos/msdos.o$:
|| m:fs/nls/nls.o$:
|| m:fs/ramfs/ramfs.o$:
|| m:fs/romfs/romfs.o$:
|| m:fs/vfat/vfat.o$:
|| m:init/mounts.o$:
|| m:^modules/:
|| m:net/netlink/netlink.o$:
|| m:net/sched/sched.o$:
|| m:/piggy.o$:
|| m:^scripts/:
|| m:sound/.*/snd-:
|| m:^.*/\.tmp_:
|| m:^\.tmp_:
|| m:/vmlinux-obj.o$:
|| m:^tools/:
)
) {
do_nm($basename, $_);
}
$_ = $basename; # File::Find expects $_ untouched (undocumented)
}
sub do_nm
{
my ($basename, $fullname) = @_;
my ($source, $type, $name);
if (! -e $basename) {
printf STDERR "$basename does not exist\n";
return;
}
if ($fullname !~ /\.o$/) {
printf STDERR "$fullname is not an object file\n";
return;
}
($source = $basename) =~ s/\.o$//;
if (-e "$source.c" || -e "$source.S") {
$source = "$objtree$File::Find::dir/$source";
} else {
$source = "$srctree$File::Find::dir/$source";
}
if (! -e "$source.c" && ! -e "$source.S") {
# No obvious source, exclude the object if it is conglomerate
open(my $objdumpdata, "$objdump $basename|")
or die "$objdump $fullname failed $!\n";
my $comment;
while (<$objdumpdata>) {
chomp();
if (/^In archive/) {
# Archives are always conglomerate
$comment = "GCC:GCC:";
last;
}
next if (! /^[ 0-9a-f]{5,} /);
$comment .= substr($_, 43);
}
close($objdumpdata);
if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) {
printf STDERR "No source file found for $fullname\n";
}
return;
}
open (my $nmdata, "$nm $basename|")
or die "$nm $fullname failed $!\n";
my @nmdata;
while (<$nmdata>) {
chop;
($type, $name) = (split(/ +/, $_, 3))[1..2];
# Expected types
# A absolute symbol
# B weak external reference to data that has been resolved
# C global variable, uninitialised
# D global variable, initialised
# G global variable, initialised, small data section
# R global array, initialised
# S global variable, uninitialised, small bss
# T global label/procedure
# U external reference
# W weak external reference to text that has been resolved
# V similar to W, but the value of the weak symbol becomes zero with no error.
# a assembler equate
# b static variable, uninitialised
# d static variable, initialised
# g static variable, initialised, small data section
# r static array, initialised
# s static variable, uninitialised, small bss
# t static label/procedures
# w weak external reference to text that has not been resolved
# v similar to w
# ? undefined type, used a lot by modules
if ($type !~ /^[ABCDGRSTUWVabdgrstwv?]$/) {
printf STDERR "nm output for $fullname contains unknown type '$_'\n";
}
elsif ($name =~ /\./) {
# name with '.' is local static
}
else {
$type = 'R' if ($type eq '?'); # binutils replaced ? with R at one point
# binutils keeps changing the type for exported symbols, force it to R
$type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/);
$name =~ s/_R[a-f0-9]{8}$//; # module versions adds this
if ($type =~ /[ABCDGRSTWV]/ &&
$name ne 'init_module' &&
$name ne 'cleanup_module' &&
$name ne 'Using_Versions' &&
$name !~ /^Version_[0-9]+$/ &&
$name !~ /^__parm_/ &&
$name !~ /^__kstrtab/ &&
$name !~ /^__ksymtab/ &&
$name !~ /^__kcrctab_/ &&
$name !~ /^__exitcall_/ &&
$name !~ /^__initcall_/ &&
$name !~ /^__kdb_initcall_/ &&
$name !~ /^__kdb_exitcall_/ &&
$name !~ /^__module_/ &&
$name !~ /^__mod_/ &&
$name !~ /^__crc_/ &&
$name ne '__this_module' &&
$name ne 'kernel_version') {
if (!exists($def{$name})) {
$def{$name} = [];
}
push(@{$def{$name}}, $fullname);
}
push(@nmdata, "$type $name");
if ($name =~ /^__ksymtab_/) {
$name = substr($name, 10);
if (!exists($ksymtab{$name})) {
$ksymtab{$name} = [];
}
push(@{$ksymtab{$name}}, $fullname);
}
}
}
close($nmdata);
if ($#nmdata < 0) {
printf "No nm data for $fullname\n"
unless $nmexception{$fullname};
return;
}
$nmdata{$fullname} = \@nmdata;
}
sub drop_def
{
my ($object, $name) = @_;
my $nmdata = $nmdata{$object};
my ($i, $j);
for ($i = 0; $i <= $#{$nmdata}; ++$i) {
if ($name eq (split(' ', $nmdata->[$i], 2))[1]) {
splice(@{$nmdata{$object}}, $i, 1);
my $def = $def{$name};
for ($j = 0; $j < $#{$def{$name}}; ++$j) {
if ($def{$name}[$j] eq $object) {
splice(@{$def{$name}}, $j, 1);
}
}
last;
}
}
}
sub list_multiply_defined
{
foreach my $name (keys(%def)) {
if ($#{$def{$name}} > 0) {
# Special case for cond_syscall
if ($#{$def{$name}} == 1 &&
($name =~ /^sys_/ || $name =~ /^compat_sys_/ ||
$name =~ /^sys32_/)) {
if($def{$name}[0] eq "kernel/sys_ni.o" ||
$def{$name}[1] eq "kernel/sys_ni.o") {
&drop_def("kernel/sys_ni.o", $name);
next;
}
}
printf "$name is multiply defined in :-\n";
foreach my $module (@{$def{$name}}) {
printf "\t$module\n";
}
}
}
}
sub resolve_external_references
{
my ($kstrtab, $ksymtab, $export);
printf "\n";
foreach my $object (keys(%nmdata)) {
my $nmdata = $nmdata{$object};
for (my $i = 0; $i <= $#{$nmdata}; ++$i) {
my ($type, $name) = split(' ', $nmdata->[$i], 2);
if ($type eq "U" || $type eq "w") {
if (exists($def{$name}) || exists($ksymtab{$name})) {
# add the owning object to the nmdata
$nmdata->[$i] = "$type $name $object";
# only count as a reference if it is not EXPORT_...
$kstrtab = "R __kstrtab_$name";
$ksymtab = "R __ksymtab_$name";
$export = 0;
for (my $j = 0; $j <= $#{$nmdata}; ++$j) {
if ($nmdata->[$j] eq $kstrtab ||
$nmdata->[$j] eq $ksymtab) {
$export = 1;
last;
}
}
if ($export) {
$export{$name} = "";
}
else {
$ref{$name} = ""
}
}
elsif ( ! $nameexception{$name}
&& $name !~ /^__sched_text_/
&& $name !~ /^__start_/
&& $name !~ /^__end_/
&& $name !~ /^__stop_/
&& $name !~ /^__scheduling_functions_.*_here/
&& $name !~ /^__.*initcall_/
&& $name !~ /^__.*per_cpu_start/
&& $name !~ /^__.*per_cpu_end/
&& $name !~ /^__alt_instructions/
&& $name !~ /^__setup_/
&& $name !~ /^__mod_timer/
&& $name !~ /^__mod_page_state/
&& $name !~ /^init_module/
&& $name !~ /^cleanup_module/
) {
printf "Cannot resolve ";
printf "weak " if ($type eq "w");
printf "reference to $name from $object\n";
}
}
}
}
}
sub list_extra_externals
{
my %noref = ();
foreach my $name (keys(%def)) {
if (! exists($ref{$name})) {
my @module = @{$def{$name}};
foreach my $module (@module) {
if (! exists($noref{$module})) {
$noref{$module} = [];
}
push(@{$noref{$module}}, $name);
}
}
}
if (%noref) {
printf "\nExternally defined symbols with no external references\n";
foreach my $module (sort(keys(%noref))) {
printf " $module\n";
foreach (sort(@{$noref{$module}})) {
my $export;
if (exists($export{$_})) {
$export = " (export only)";
} else {
$export = "";
}
printf " $_$export\n";
}
}
}
}
