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 open(my $objdumpdata, "$objdump $basename|") 179 or die "$objdump $fullname failed $!\n"; 180 181 my $comment; 182 while (<$objdumpdata>) { 183 chomp(); 184 if (/^In archive/) { 185 # Archives are always conglomerate 186 $comment = "GCC:GCC:"; 187 last; 188 } 189 next if (! /^[ 0-9a-f]{5,} /); 190 $comment .= substr($_, 43); 191 } 192 close($objdumpdata); 193 194 if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) { 195 printf STDERR "No source file found for $fullname\n"; 196 } 197 return; 198 } 199 open (my $nmdata, "$nm $basename|") 200 or die "$nm $fullname failed $!\n"; 201 202 my @nmdata; 203 while (<$nmdata>) { 204 chop; 205 ($type, $name) = (split(/ +/, $_, 3))[1..2]; 206 # Expected types 207 # A absolute symbol 208 # B weak external reference to data that has been resolved 209 # C global variable, uninitialised 210 # D global variable, initialised 211 # G global variable, initialised, small data section 212 # R global array, initialised 213 # S global variable, uninitialised, small bss 214 # T global label/procedure 215 # U external reference 216 # W weak external reference to text that has been resolved 217 # a assembler equate 218 # b static variable, uninitialised 219 # d static variable, initialised 220 # g static variable, initialised, small data section 221 # r static array, initialised 222 # s static variable, uninitialised, small bss 223 # t static label/procedures 224 # w weak external reference to text that has not been resolved 225 # ? undefined type, used a lot by modules 226 if ($type !~ /^[ABCDGRSTUWabdgrstw?]$/) { 227 printf STDERR "nm output for $fullname contains unknown type '$_'\n"; 228 } 229 elsif ($name =~ /\./) { 230 # name with '.' is local static 231 } 232 else { 233 $type = 'R' if ($type eq '?'); # binutils replaced ? with R at one point 234 # binutils keeps changing the type for exported symbols, force it to R 235 $type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/); 236 $name =~ s/_R[a-f0-9]{8}$//; # module versions adds this 237 if ($type =~ /[ABCDGRSTW]/ && 238 $name ne 'init_module' && 239 $name ne 'cleanup_module' && 240 $name ne 'Using_Versions' && 241 $name !~ /^Version_[0-9]+$/ && 242 $name !~ /^__parm_/ && 243 $name !~ /^__kstrtab/ && 244 $name !~ /^__ksymtab/ && 245 $name !~ /^__kcrctab_/ && 246 $name !~ /^__exitcall_/ && 247 $name !~ /^__initcall_/ && 248 $name !~ /^__kdb_initcall_/ && 249 $name !~ /^__kdb_exitcall_/ && 250 $name !~ /^__module_/ && 251 $name !~ /^__mod_/ && 252 $name !~ /^__crc_/ && 253 $name ne '__this_module' && 254 $name ne 'kernel_version') { 255 if (!exists($def{$name})) { 256 $def{$name} = []; 257 } 258 push(@{$def{$name}}, $fullname); 259 } 260 push(@nmdata, "$type $name"); 261 if ($name =~ /^__ksymtab_/) { 262 $name = substr($name, 10); 263 if (!exists($ksymtab{$name})) { 264 $ksymtab{$name} = []; 265 } 266 push(@{$ksymtab{$name}}, $fullname); 267 } 268 } 269 } 270 close($nmdata); 271 272 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 foreach my $name (keys(%def)) { 320 if ($#{$def{$name}} > 0) { 321 # Special case for cond_syscall 322 if ($#{$def{$name}} == 1 && $name =~ /^sys_/ && 323 ($def{$name}[0] eq "kernel/sys.o" || 324 $def{$name}[1] eq "kernel/sys.o")) { 325 &drop_def("kernel/sys.o", $name); 326 next; 327 } 328 # Special case for i386 entry code 329 if ($#{$def{$name}} == 1 && $name =~ /^__kernel_/ && 330 $def{$name}[0] eq "arch/x86/kernel/vsyscall-int80_32.o" && 331 $def{$name}[1] eq "arch/x86/kernel/vsyscall-sysenter_32.o") { 332 &drop_def("arch/x86/kernel/vsyscall-sysenter_32.o", $name); 333 next; 334 } 335 336 printf "$name is multiply defined in :-\n"; 337 foreach my $module (@{$def{$name}}) { 338 printf "\t$module\n"; 339 } 340 } 341 } 342} 343 344sub resolve_external_references 345{ 346 my ($kstrtab, $ksymtab, $export); 347 348 printf "\n"; 349 foreach my $object (keys(%nmdata)) { 350 my $nmdata = $nmdata{$object}; 351 for (my $i = 0; $i <= $#{$nmdata}; ++$i) { 352 my ($type, $name) = split(' ', $nmdata->[$i], 2); 353 if ($type eq "U" || $type eq "w") { 354 if (exists($def{$name}) || exists($ksymtab{$name})) { 355 # add the owning object to the nmdata 356 $nmdata->[$i] = "$type $name $object"; 357 # only count as a reference if it is not EXPORT_... 358 $kstrtab = "R __kstrtab_$name"; 359 $ksymtab = "R __ksymtab_$name"; 360 $export = 0; 361 for (my $j = 0; $j <= $#{$nmdata}; ++$j) { 362 if ($nmdata->[$j] eq $kstrtab || 363 $nmdata->[$j] eq $ksymtab) { 364 $export = 1; 365 last; 366 } 367 } 368 if ($export) { 369 $export{$name} = ""; 370 } 371 else { 372 $ref{$name} = "" 373 } 374 } 375 elsif ( $name ne "mod_use_count_" 376 && $name ne "__initramfs_end" 377 && $name ne "__initramfs_start" 378 && $name ne "_einittext" 379 && $name ne "_sinittext" 380 && $name ne "kallsyms_names" 381 && $name ne "kallsyms_num_syms" 382 && $name ne "kallsyms_addresses" 383 && $name ne "__this_module" 384 && $name ne "_etext" 385 && $name ne "_edata" 386 && $name ne "_end" 387 && $name ne "__bss_start" 388 && $name ne "_text" 389 && $name ne "_stext" 390 && $name ne "__gp" 391 && $name ne "ia64_unw_start" 392 && $name ne "ia64_unw_end" 393 && $name ne "__init_begin" 394 && $name ne "__init_end" 395 && $name ne "__bss_stop" 396 && $name ne "__nosave_begin" 397 && $name ne "__nosave_end" 398 && $name ne "pg0" 399 && $name ne "__module_text_address" 400 && $name !~ /^__sched_text_/ 401 && $name !~ /^__start_/ 402 && $name !~ /^__end_/ 403 && $name !~ /^__stop_/ 404 && $name !~ /^__scheduling_functions_.*_here/ 405 && $name !~ /^__.*initcall_/ 406 && $name !~ /^__.*per_cpu_start/ 407 && $name !~ /^__.*per_cpu_end/ 408 && $name !~ /^__alt_instructions/ 409 && $name !~ /^__setup_/ 410 && $name !~ /^jiffies/ 411 && $name !~ /^__mod_timer/ 412 && $name !~ /^__mod_page_state/ 413 && $name !~ /^init_module/ 414 && $name !~ /^cleanup_module/ 415 ) { 416 printf "Cannot resolve "; 417 printf "weak " if ($type eq "w"); 418 printf "reference to $name from $object\n"; 419 } 420 } 421 } 422 } 423} 424 425sub list_extra_externals 426{ 427 my %noref = (); 428 429 foreach my $name (keys(%def)) { 430 if (! exists($ref{$name})) { 431 my @module = @{$def{$name}}; 432 foreach my $module (@module) { 433 if (! exists($noref{$module})) { 434 $noref{$module} = []; 435 } 436 push(@{$noref{$module}}, $name); 437 } 438 } 439 } 440 if (%noref) { 441 printf "\nExternally defined symbols with no external references\n"; 442 foreach my $module (sort(keys(%noref))) { 443 printf " $module\n"; 444 foreach (sort(@{$noref{$module}})) { 445 my $export; 446 if (exists($export{$_})) { 447 $export = " (export only)"; 448 } else { 449 $export = ""; 450 } 451 printf " $_$export\n"; 452 } 453 } 454 } 455} 456