scripts/reference_init.pl

   1 #!/usr/bin/perl -w
   2 #
   3 # reference_init.pl (C) Keith Owens 2002 <kaos@ocs.com.au>
   4 #
   5 # List references to vmlinux init sections from non-init sections.
   6
   7 # Unfortunately I had to exclude references from read only data to .init
   8 # sections, almost all of these are false positives, they are created by
   9 # gcc.  The downside of excluding rodata is that there really are some
  10 # user references from rodata to init code, e.g. drivers/video/vgacon.c
  11 #
  12 # const struct consw vga_con = {
  13 #        con_startup:            vgacon_startup,
  14 #
  15 # where vgacon_startup is __init.  If you want to wade through the false
  16 # positives, take out the check for rodata.
  17
  18 use strict;
  19 die($0 . " takes no arguments\n") if($#ARGV >= 0);
  20
  21 my %object;
  22 my $object;
  23 my $line;
  24 my $ignore;
  25
  26 $| = 1;
  27
  28 printf("Finding objects, ");
  29 open(OBJDUMP_LIST, "find . -name '*.o' | xargs objdump -h |") || die "getting objdump list failed";
  30 while (defined($line = <OBJDUMP_LIST>)) {
  31         chomp($line);
  32         if ($line =~ /:\s+file format/) {
  33                 ($object = $line) =~ s/:.*//;
  34                 $object{$object}->{'module'} = 0;
  35                 $object{$object}->{'size'} = 0;
  36                 $object{$object}->{'off'} = 0;
  37         }
  38         if ($line =~ /^\s*\d+\s+\.modinfo\s+/) {
  39                 $object{$object}->{'module'} = 1;
  40         }
  41         if ($line =~ /^\s*\d+\s+\.comment\s+/) {
  42                 ($object{$object}->{'size'}, $object{$object}->{'off'}) = (split(' ', $line))[2,5];
  43         }
  44 }
  45 close(OBJDUMP_LIST);
  46 printf("%d objects, ", scalar keys(%object));
  47 $ignore = 0;
  48 foreach $object (keys(%object)) {
  49         if ($object{$object}->{'module'}) {
  50                 ++$ignore;
  51                 delete($object{$object});
  52         }
  53 }
  54 printf("ignoring %d module(s)\n", $ignore);
  55
  56 # Ignore conglomerate objects, they have been built from multiple objects and we
  57 # only care about the individual objects.  If an object has more than one GCC:
  58 # string in the comment section then it is conglomerate.  This does not filter
  59 # out conglomerates that consist of exactly one object, can't be helped.
  60
  61 printf("Finding conglomerates, ");
  62 $ignore = 0;
  63 foreach $object (keys(%object)) {
  64         if (exists($object{$object}->{'off'})) {
  65                 my ($off, $size, $comment, $l);
  66                 $off = hex($object{$object}->{'off'});
  67                 $size = hex($object{$object}->{'size'});
  68                 open(OBJECT, "<$object") || die "cannot read $object";
  69                 seek(OBJECT, $off, 0) || die "seek to $off in $object failed";
  70                 $l = read(OBJECT, $comment, $size);
  71                 die "read $size bytes from $object .comment failed" if ($l != $size);
  72                 close(OBJECT);
  73                 if ($comment =~ /GCC\:.*GCC\:/m) {
  74                         ++$ignore;
  75                         delete($object{$object});
  76                 }
  77         }
  78 }
  79 printf("ignoring %d conglomerate(s)\n", $ignore);
  80
  81 printf("Scanning objects\n");
  82 foreach $object (sort(keys(%object))) {
  83         my $from;
  84         open(OBJDUMP, "objdump -r $object|") || die "cannot objdump -r $object";
  85         while (defined($line = <OBJDUMP>)) {
  86                 chomp($line);
  87                 if ($line =~ /RELOCATION RECORDS FOR /) {
  88                         ($from = $line) =~ s/.*\[([^]]*).*/$1/;
  89                 }
  90                 if (($line =~ /\.init$/ || $line =~ /\.init\./) &&
  91                     ($from !~ /\.init$/ &&
  92                      $from !~ /\.init\./ &&
  93                      $from !~ /\.stab$/ &&
  94                      $from !~ /\.rodata$/ &&
  95                      $from !~ /\.text\.lock$/ &&
  96                      $from !~ /\.debug_/)) {
  97                         printf("Error: %s %s refers to %s\n", $object, $from, $line);
  98                 }
  99         }
 100         close(OBJDUMP);
 101 }
 102 printf("Done\n");