Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/scripts/namespace.pl
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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 65 require 5; # at least perl 5 66 use strict; 67 use File::Find; 68 69 my $nm = ($ENV{'NM'} || "nm") . " -p"; 70 my $objdump = ($ENV{'OBJDUMP'} || "objdump") . " -s -j .comment"; 71 my $srctree = ""; 72 my $objtree = ""; 73 $srctree = "$ENV{'srctree'}/" if (exists($ENV{'srctree'})); 74 $objtree = "$ENV{'objtree'}/" if (exists($ENV{'objtree'})); 75 76 if ($#ARGV != -1) { 77 print STDERR "usage: $0 takes no parameters\n"; 78 die("giving up\n"); 79 } 80 81 my %nmdata = (); # nm data for each object 82 my %def = (); # all definitions for each name 83 my %ksymtab = (); # names that appear in __ksymtab_ 84 my %ref = (); # $ref{$name} exists if there is a true external reference to $name 85 my %export = (); # $export{$name} exists if there is an EXPORT_... of $name 86 87 my %nmexception = ( 88 'fs/ext3/bitmap' => 1, 89 'fs/ext4/bitmap' => 1, 90 'arch/x86/lib/thunk_32' => 1, 91 'arch/x86/lib/cmpxchg' => 1, 92 'arch/x86/vdso/vdso32/note' => 1, 93 'lib/irq_regs' => 1, 94 'usr/initramfs_data' => 1, 95 'drivers/scsi/aic94xx/aic94xx_dump' => 1, 96 'drivers/scsi/libsas/sas_dump' => 1, 97 'lib/dec_and_lock' => 1, 98 'drivers/ide/ide-probe-mini' => 1, 99 'usr/initramfs_data' => 1, 100 'drivers/acpi/acpia/exdump' => 1, 101 'drivers/acpi/acpia/rsdump' => 1, 102 'drivers/acpi/acpia/nsdumpdv' => 1, 103 'drivers/acpi/acpia/nsdump' => 1, 104 'arch/ia64/sn/kernel/sn2/io' => 1, 105 'arch/ia64/kernel/gate-data' => 1, 106 'security/capability' => 1, 107 'fs/ntfs/sysctl' => 1, 108 'fs/jfs/jfs_debug' => 1, 109 ); 110 111 my %nameexception = ( 112 'mod_use_count_' => 1, 113 '__initramfs_end' => 1, 114 '__initramfs_start' => 1, 115 '_einittext' => 1, 116 '_sinittext' => 1, 117 'kallsyms_names' => 1, 118 'kallsyms_num_syms' => 1, 119 'kallsyms_addresses'=> 1, 120 '__this_module' => 1, 121 '_etext' => 1, 122 '_edata' => 1, 123 '_end' => 1, 124 '__bss_start' => 1, 125 '_text' => 1, 126 '_stext' => 1, 127 '__gp' => 1, 128 'ia64_unw_start' => 1, 129 'ia64_unw_end' => 1, 130 '__init_begin' => 1, 131 '__init_end' => 1, 132 '__bss_stop' => 1, 133 '__nosave_begin' => 1, 134 '__nosave_end' => 1, 135 'pg0' => 1, 136 'vdso_enabled' => 1, 137 '__stack_chk_fail' => 1, 138 'VDSO32_PRELINK' => 1, 139 'VDSO32_vsyscall' => 1, 140 'VDSO32_rt_sigreturn'=>1, 141 'VDSO32_sigreturn' => 1, 142 ); 143 144 145 &find(\&linux_objects, '.'); # find the objects and do_nm on them 146 &list_multiply_defined(); 147 &resolve_external_references(); 148 &list_extra_externals(); 149 150 exit(0); 151 152 sub linux_objects 153 { 154 # Select objects, ignoring objects which are only created by 155 # merging other objects. Also ignore all of modules, scripts 156 # and compressed. Most conglomerate objects are handled by do_nm, 157 # this list only contains the special cases. These include objects 158 # that are linked from just one other object and objects for which 159 # there is really no permanent source file. 160 my $basename = $_; 161 $_ = $File::Find::name; 162 s:^\./::; 163 if (/.*\.o$/ && 164 ! ( 165 m:/built-in.o$: 166 || m:arch/x86/vdso/: 167 || m:arch/x86/boot/: 168 || m:arch/ia64/ia32/ia32.o$: 169 || m:arch/ia64/kernel/gate-syms.o$: 170 || m:arch/ia64/lib/__divdi3.o$: 171 || m:arch/ia64/lib/__divsi3.o$: 172 || m:arch/ia64/lib/__moddi3.o$: 173 || m:arch/ia64/lib/__modsi3.o$: 174 || m:arch/ia64/lib/__udivdi3.o$: 175 || m:arch/ia64/lib/__udivsi3.o$: 176 || m:arch/ia64/lib/__umoddi3.o$: 177 || m:arch/ia64/lib/__umodsi3.o$: 178 || m:arch/ia64/scripts/check_gas_for_hint.o$: 179 || m:arch/ia64/sn/kernel/xp.o$: 180 || m:boot/bbootsect.o$: 181 || m:boot/bsetup.o$: 182 || m:/bootsect.o$: 183 || m:/boot/setup.o$: 184 || m:/compressed/: 185 || m:drivers/cdrom/driver.o$: 186 || m:drivers/char/drm/tdfx_drv.o$: 187 || m:drivers/ide/ide-detect.o$: 188 || m:drivers/ide/pci/idedriver-pci.o$: 189 || m:drivers/media/media.o$: 190 || m:drivers/scsi/sd_mod.o$: 191 || m:drivers/video/video.o$: 192 || m:fs/devpts/devpts.o$: 193 || m:fs/exportfs/exportfs.o$: 194 || m:fs/hugetlbfs/hugetlbfs.o$: 195 || m:fs/msdos/msdos.o$: 196 || m:fs/nls/nls.o$: 197 || m:fs/ramfs/ramfs.o$: 198 || m:fs/romfs/romfs.o$: 199 || m:fs/vfat/vfat.o$: 200 || m:init/mounts.o$: 201 || m:^modules/: 202 || m:net/netlink/netlink.o$: 203 || m:net/sched/sched.o$: 204 || m:/piggy.o$: 205 || m:^scripts/: 206 || m:sound/.*/snd-: 207 || m:^.*/\.tmp_: 208 || m:^\.tmp_: 209 || m:/vmlinux-obj.o$: 210 || m:^tools/: 211 ) 212 ) { 213 do_nm($basename, $_); 214 } 215 $_ = $basename; # File::Find expects $_ untouched (undocumented) 216 } 217 218 sub do_nm 219 { 220 my ($basename, $fullname) = @_; 221 my ($source, $type, $name); 222 if (! -e $basename) { 223 printf STDERR "$basename does not exist\n"; 224 return; 225 } 226 if ($fullname !~ /\.o$/) { 227 printf STDERR "$fullname is not an object file\n"; 228 return; 229 } 230 ($source = $basename) =~ s/\.o$//; 231 if (-e "$source.c" || -e "$source.S") { 232 $source = "$objtree$File::Find::dir/$source"; 233 } else { 234 $source = "$srctree$File::Find::dir/$source"; 235 } 236 if (! -e "$source.c" && ! -e "$source.S") { 237 # No obvious source, exclude the object if it is conglomerate 238 open(my $objdumpdata, "$objdump $basename|") 239 or die "$objdump $fullname failed $!\n"; 240 241 my $comment; 242 while (<$objdumpdata>) { 243 chomp(); 244 if (/^In archive/) { 245 # Archives are always conglomerate 246 $comment = "GCC:GCC:"; 247 last; 248 } 249 next if (! /^[ 0-9a-f]{5,} /); 250 $comment .= substr($_, 43); 251 } 252 close($objdumpdata); 253 254 if (!defined($comment) || $comment !~ /GCC\:.*GCC\:/m) { 255 printf STDERR "No source file found for $fullname\n"; 256 } 257 return; 258 } 259 open (my $nmdata, "$nm $basename|") 260 or die "$nm $fullname failed $!\n"; 261 262 my @nmdata; 263 while (<$nmdata>) { 264 chop; 265 ($type, $name) = (split(/ +/, $_, 3))[1..2]; 266 # Expected types 267 # A absolute symbol 268 # B weak external reference to data that has been resolved 269 # C global variable, uninitialised 270 # D global variable, initialised 271 # G global variable, initialised, small data section 272 # R global array, initialised 273 # S global variable, uninitialised, small bss 274 # T global label/procedure 275 # U external reference 276 # W weak external reference to text that has been resolved 277 # V similar to W, but the value of the weak symbol becomes zero with no error. 278 # a assembler equate 279 # b static variable, uninitialised 280 # d static variable, initialised 281 # g static variable, initialised, small data section 282 # r static array, initialised 283 # s static variable, uninitialised, small bss 284 # t static label/procedures 285 # w weak external reference to text that has not been resolved 286 # v similar to w 287 # ? undefined type, used a lot by modules 288 if ($type !~ /^[ABCDGRSTUWVabdgrstwv?]$/) { 289 printf STDERR "nm output for $fullname contains unknown type '$_'\n"; 290 } 291 elsif ($name =~ /\./) { 292 # name with '.' is local static 293 } 294 else { 295 $type = 'R' if ($type eq '?'); # binutils replaced ? with R at one point 296 # binutils keeps changing the type for exported symbols, force it to R 297 $type = 'R' if ($name =~ /^__ksymtab/ || $name =~ /^__kstrtab/); 298 $name =~ s/_R[a-f0-9]{8}$//; # module versions adds this 299 if ($type =~ /[ABCDGRSTWV]/ && 300 $name ne 'init_module' && 301 $name ne 'cleanup_module' && 302 $name ne 'Using_Versions' && 303 $name !~ /^Version_[0-9]+$/ && 304 $name !~ /^__parm_/ && 305 $name !~ /^__kstrtab/ && 306 $name !~ /^__ksymtab/ && 307 $name !~ /^__kcrctab_/ && 308 $name !~ /^__exitcall_/ && 309 $name !~ /^__initcall_/ && 310 $name !~ /^__kdb_initcall_/ && 311 $name !~ /^__kdb_exitcall_/ && 312 $name !~ /^__module_/ && 313 $name !~ /^__mod_/ && 314 $name !~ /^__crc_/ && 315 $name ne '__this_module' && 316 $name ne 'kernel_version') { 317 if (!exists($def{$name})) { 318 $def{$name} = []; 319 } 320 push(@{$def{$name}}, $fullname); 321 } 322 push(@nmdata, "$type $name"); 323 if ($name =~ /^__ksymtab_/) { 324 $name = substr($name, 10); 325 if (!exists($ksymtab{$name})) { 326 $ksymtab{$name} = []; 327 } 328 push(@{$ksymtab{$name}}, $fullname); 329 } 330 } 331 } 332 close($nmdata); 333 334 if ($#nmdata < 0) { 335 printf "No nm data for $fullname\n" 336 unless $nmexception{$fullname}; 337 return; 338 } 339 $nmdata{$fullname} = \@nmdata; 340 } 341 342 sub drop_def 343 { 344 my ($object, $name) = @_; 345 my $nmdata = $nmdata{$object}; 346 my ($i, $j); 347 for ($i = 0; $i <= $#{$nmdata}; ++$i) { 348 if ($name eq (split(' ', $nmdata->[$i], 2))[1]) { 349 splice(@{$nmdata{$object}}, $i, 1); 350 my $def = $def{$name}; 351 for ($j = 0; $j < $#{$def{$name}}; ++$j) { 352 if ($def{$name}[$j] eq $object) { 353 splice(@{$def{$name}}, $j, 1); 354 } 355 } 356 last; 357 } 358 } 359 } 360 361 sub list_multiply_defined 362 { 363 foreach my $name (keys(%def)) { 364 if ($#{$def{$name}} > 0) { 365 # Special case for cond_syscall 366 if ($#{$def{$name}} == 1 && 367 ($name =~ /^sys_/ || $name =~ /^compat_sys_/ || 368 $name =~ /^sys32_/)) { 369 if($def{$name}[0] eq "kernel/sys_ni.o" || 370 $def{$name}[1] eq "kernel/sys_ni.o") { 371 &drop_def("kernel/sys_ni.o", $name); 372 next; 373 } 374 } 375 376 printf "$name is multiply defined in :-\n"; 377 foreach my $module (@{$def{$name}}) { 378 printf "\t$module\n"; 379 } 380 } 381 } 382 } 383 384 sub resolve_external_references 385 { 386 my ($kstrtab, $ksymtab, $export); 387 388 printf "\n"; 389 foreach my $object (keys(%nmdata)) { 390 my $nmdata = $nmdata{$object}; 391 for (my $i = 0; $i <= $#{$nmdata}; ++$i) { 392 my ($type, $name) = split(' ', $nmdata->[$i], 2); 393 if ($type eq "U" || $type eq "w") { 394 if (exists($def{$name}) || exists($ksymtab{$name})) { 395 # add the owning object to the nmdata 396 $nmdata->[$i] = "$type $name $object"; 397 # only count as a reference if it is not EXPORT_... 398 $kstrtab = "R __kstrtab_$name"; 399 $ksymtab = "R __ksymtab_$name"; 400 $export = 0; 401 for (my $j = 0; $j <= $#{$nmdata}; ++$j) { 402 if ($nmdata->[$j] eq $kstrtab || 403 $nmdata->[$j] eq $ksymtab) { 404 $export = 1; 405 last; 406 } 407 } 408 if ($export) { 409 $export{$name} = ""; 410 } 411 else { 412 $ref{$name} = "" 413 } 414 } 415 elsif ( ! $nameexception{$name} 416 && $name !~ /^__sched_text_/ 417 && $name !~ /^__start_/ 418 && $name !~ /^__end_/ 419 && $name !~ /^__stop_/ 420 && $name !~ /^__scheduling_functions_.*_here/ 421 && $name !~ /^__.*initcall_/ 422 && $name !~ /^__.*per_cpu_start/ 423 && $name !~ /^__.*per_cpu_end/ 424 && $name !~ /^__alt_instructions/ 425 && $name !~ /^__setup_/ 426 && $name !~ /^__mod_timer/ 427 && $name !~ /^__mod_page_state/ 428 && $name !~ /^init_module/ 429 && $name !~ /^cleanup_module/ 430 ) { 431 printf "Cannot resolve "; 432 printf "weak " if ($type eq "w"); 433 printf "reference to $name from $object\n"; 434 } 435 } 436 } 437 } 438 } 439 440 sub list_extra_externals 441 { 442 my %noref = (); 443 444 foreach my $name (keys(%def)) { 445 if (! exists($ref{$name})) { 446 my @module = @{$def{$name}}; 447 foreach my $module (@module) { 448 if (! exists($noref{$module})) { 449 $noref{$module} = []; 450 } 451 push(@{$noref{$module}}, $name); 452 } 453 } 454 } 455 if (%noref) { 456 printf "\nExternally defined symbols with no external references\n"; 457 foreach my $module (sort(keys(%noref))) { 458 printf " $module\n"; 459 foreach (sort(@{$noref{$module}})) { 460 my $export; 461 if (exists($export{$_})) { 462 $export = " (export only)"; 463 } else { 464 $export = ""; 465 } 466 printf " $_$export\n"; 467 } 468 } 469 } 470 }
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