#!/usr/bin/perl -w
#
#       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.
#

require 5;      # at least perl 5
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

&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.o$:
                || m:arch/x86/kernel/vsyscall-syms.o$:
                || 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$:
                || m:^scripts/:
                || m:sound/.*/snd-:
                || m:^.*/\.tmp_:
                || m:^\.tmp_:
                || m:/vmlinux-obj.o$:
                )
        ) {
                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 = $fullname) =~ s/\.o$//;
        if (-e "$objtree$source.c" || -e "$objtree$source.S") {
                $source = "$objtree$source";
        } else {
                $source = "$srctree$source";
        }
        if (! -e "$source.c" && ! -e "$source.S") {
                # No obvious source, exclude the object if it is conglomerate
                if (! open(OBJDUMPDATA, "$objdump $basename|")) {
                        printf STDERR "$objdump $fullname failed $!\n";
                        return;
                }
                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 $fullname\n";
                }
                return;
        }
        if (! open(NMDATA, "$nm $basename|")) {
                printf STDERR "$nm $fullname failed $!\n";
                return;
        }
        my @nmdata;
        while (<NMDATA>) {
                chop;
                ($type, $name) = (split(/ +/, $_, 3))[1..2];
                # Expected types
                # A absolute symbol
                # B weak external reference to data that has been resolved
                # C global variable, uninitialised
                # D global variable, initialised
                # G global variable, initialised, small data section
                # R global array, initialised
                # S global variable, uninitialised, small bss
                # T global label/procedure
                # U external reference
                # W weak external reference to text that has been resolved
                # a assembler equate
                # b static variable, uninitialised
                # d static variable, initialised
                # g static variable, initialised, small data section
                # r static array, initialised
                # s static variable, uninitialised, small bss
                # t static label/procedures
                # w weak external reference to text that has not been resolved
                # ? undefined type, used a lot by modules
                if ($type !~ /^[ABCDGRSTUWabdgrstw?]$/) {
                        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 =~ /[ABCDGRSTW]/ &&
                                $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) {
                if (
                        $fullname ne "lib/brlock.o"
                        && $fullname ne "lib/dec_and_lock.o"
                        && $fullname ne "fs/xfs/xfs_macros.o"
                        && $fullname ne "drivers/ide/ide-probe-mini.o"
                        && $fullname ne "usr/initramfs_data.o"
                        && $fullname ne "drivers/acpi/executer/exdump.o"
                        && $fullname ne "drivers/acpi/resources/rsdump.o"
                        && $fullname ne "drivers/acpi/namespace/nsdumpdv.o"
                        && $fullname ne "drivers/acpi/namespace/nsdump.o"
                        && $fullname ne "arch/ia64/sn/kernel/sn2/io.o"
                        && $fullname ne "arch/ia64/kernel/gate-data.o"
                        && $fullname ne "drivers/ieee1394/oui.o"
                        && $fullname ne "security/capability.o"
                        && $fullname ne "sound/core/wrappers.o"
                        && $fullname ne "fs/ntfs/sysctl.o"
                        && $fullname ne "fs/jfs/jfs_debug.o"
                ) {
                        printf "No nm data for $fullname\n";
                }
                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
{
        my ($name, $module);
        foreach $name (keys(%def)) {
                if ($#{$def{$name}} > 0) {
                        # Special case for cond_syscall
                        if ($#{$def{$name}} == 1 && $name =~ /^sys_/ &&
                            ($def{$name}[0] eq "kernel/sys.o" ||
                             $def{$name}[1] eq "kernel/sys.o")) {
                                &drop_def("kernel/sys.o", $name);
                                next;
                        }
                        # Special case for i386 entry code
                        if ($#{$def{$name}} == 1 && $name =~ /^__kernel_/ &&
                            $def{$name}[0] eq "arch/x86/kernel/vsyscall-int80_32.o" &&
                            $def{$name}[1] eq "arch/x86/kernel/vsyscall-sysenter_32.o") {
                                &drop_def("arch/x86/kernel/vsyscall-sysenter_32.o", $name);
                                next;
                        }
                        printf "$name is multiply defined in :-\n";
                        foreach $module (@{$def{$name}}) {
                                printf "\t$module\n";
                        }
                }
        }
}

sub resolve_external_references
{
        my ($object, $type, $name, $i, $j, $kstrtab, $ksymtab, $export);
        printf "\n";
        foreach $object (keys(%nmdata)) {
                my $nmdata = $nmdata{$object};
                for ($i = 0; $i <= $#{$nmdata}; ++$i) {
                        ($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";
                                        $export = 0;
                                        for ($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 (    $name ne "mod_use_count_"
                                        && $name ne "__initramfs_end"
                                        && $name ne "__initramfs_start"
                                        && $name ne "_einittext"
                                        && $name ne "_sinittext"
                                        && $name ne "kallsyms_names"
                                        && $name ne "kallsyms_num_syms"
                                        && $name ne "kallsyms_addresses"
                                        && $name ne "__this_module"
                                        && $name ne "_etext"
                                        && $name ne "_edata"
                                        && $name ne "_end"
                                        && $name ne "__bss_start"
                                        && $name ne "_text"
                                        && $name ne "_stext"
                                        && $name ne "__gp"
                                        && $name ne "ia64_unw_start"
                                        && $name ne "ia64_unw_end"
                                        && $name ne "__init_begin"
                                        && $name ne "__init_end"
                                        && $name ne "__bss_stop"
                                        && $name ne "__nosave_begin"
                                        && $name ne "__nosave_end"
                                        && $name ne "pg0"
                                        && $name ne "__module_text_address"
                                        && $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 !~ /^jiffies/
                                        && $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 = ();
        my ($name, @module, $module, $export);
        foreach $name (keys(%def)) {
                if (! exists($ref{$name})) {
                        @module = @{$def{$name}};
                        foreach $module (@module) {
                                if (! exists($noref{$module})) {
                                        $noref{$module} = [];
                                }
                                push(@{$noref{$module}}, $name);
                        }
                }
        }
        if (%noref) {
                printf "\nExternally defined symbols with no external references\n";
                foreach $module (sort(keys(%noref))) {
                        printf "  $module\n";
                        foreach (sort(@{$noref{$module}})) {
                                if (exists($export{$_})) {
                                        $export = " (export only)";
                                }
                                else {
                                        $export = "";
                                }
                                printf "    $_$export\n";
                        }
                }
        }
}