#!/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"; } } } }