scripts/localplt.awk

   1 # This awk script expects to get command-line files that are each
   2 # the output of 'readelf -WSdr' on a single shared object, and named
   3 # .../NAME.jmprel where NAME is the unadorned file name of the shared object.
   4 # It writes "NAME: SYMBOL" for each PLT entry in NAME that refers to a
   5 # symbol defined in the same object.
   6
   7 BEGIN {
   8   result = 0;
   9   pltrelsize = -1;
  10 }
  11
  12 FILENAME != lastfile {
  13   if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) {
  14     print FILENAME ": *** failed to find expected output (readelf -WSdr)";
  15     result = 2;
  16   }
  17   if (pltrelsz > 0 && jmprel_offset == -1) {
  18     print FILENAME ": Could not find section for DT_JMPREL";
  19     result = 2;
  20   }
  21   lastfile = FILENAME;
  22   jmprel_offset = 0;
  23   rela_offset = 0;
  24   rel_offset = 0;
  25   pltrelsz = -1;
  26   delete section_offset_by_address;
  27 }
  28
  29 /^Section Headers:/ { in_shdrs = 1; next }
  30 in_shdrs && !/^ +\[/ { in_shdrs = 0 }
  31
  32 in_shdrs && /^ +\[/ { sub(/\[ +/, "[") }
  33 in_shdrs {
  34   address = strtonum("0x" $4);
  35   offset = strtonum("0x" $5);
  36   section_offset_by_address[address] = offset;
  37 }
  38
  39 in_shdrs { next }
  40
  41 $1 == "Offset" && $2 == "Info" { in_relocs = 1; next }
  42 NF == 0 { in_relocs = 0 }
  43
  44 in_relocs && relocs_offset == jmprel_offset && NF >= 5 {
  45   # Relocations against GNU_IFUNC symbols are not shown as an hexadecimal
  46   # value, but rather as the resolver symbol followed by ().
  47   if ($4 ~ /\(\)/) {
  48     print whatfile, gensub(/@.*/, "", "g", $5)
  49   } else {
  50     symval = strtonum("0x" $4);
  51     if (symval != 0)
  52       print whatfile, gensub(/@.*/, "", "g", $5)
  53   }
  54 }
  55
  56 in_relocs && relocs_offset == rela_offset && NF >= 5 {
  57   # Relocations against GNU_IFUNC symbols are not shown as an hexadecimal
  58   # value, but rather as the resolver symbol followed by ().
  59   if ($4 ~ /\(\)/) {
  60     print whatfile, gensub(/@.*/, "", "g", $5), "RELA", $3
  61   } else {
  62     symval = strtonum("0x" $4);
  63     if (symval != 0)
  64       print whatfile, gensub(/@.*/, "", "g", $5), "RELA", $3
  65   }
  66 }
  67
  68 in_relocs && relocs_offset == rel_offset && NF >= 5 {
  69   # Relocations against GNU_IFUNC symbols are not shown as an hexadecimal
  70   # value, but rather as the resolver symbol followed by ().
  71   if ($4 ~ /\(\)/) {
  72     print whatfile, gensub(/@.*/, "", "g", $5), "REL", $3
  73   } else {
  74     symval = strtonum("0x" $4);
  75     if (symval != 0)
  76       print whatfile, gensub(/@.*/, "", "g", $5), "REL", $3
  77   }
  78 }
  79
  80 in_relocs { next }
  81
  82 $1 == "Relocation" && $2 == "section" && $5 == "offset" {
  83   relocs_offset = strtonum($6);
  84   whatfile = gensub(/^.*\/([^/]+)\.jmprel$/, "\\1:", 1, FILENAME);
  85   next
  86 }
  87
  88 $2 == "(JMPREL)" {
  89   jmprel_addr = strtonum($3);
  90   if (jmprel_addr in section_offset_by_address) {
  91     jmprel_offset = section_offset_by_address[jmprel_addr];
  92   } else {
  93     jmprel_offset = -1
  94   }
  95   next
  96 }
  97
  98 $2 == "(PLTRELSZ)" {
  99   pltrelsz = strtonum($3);
 100   next
 101 }
 102
 103 $2 == "(RELA)" {
 104   rela_addr = strtonum($3);
 105   if (rela_addr in section_offset_by_address) {
 106     rela_offset = section_offset_by_address[rela_addr];
 107   } else {
 108     print FILENAME ": *** DT_RELA does not match any section's address";
 109     result = 2;
 110   }
 111   next
 112 }
 113
 114 $2 == "(REL)" {
 115   rel_addr = strtonum($3);
 116   if (rel_addr in section_offset_by_address) {
 117     rel_offset = section_offset_by_address[rel_addr];
 118   } else {
 119     print FILENAME ": *** DT_REL does not match any section's address";
 120     result = 2;
 121   }
 122   next
 123 }
 124 END { exit(result) }