Node.js v10 -> v12 bpftrace programs

v10-json-parse-size-load-constants.bt

// Node v10.15.3
uprobe:/home/mmarchini/.nvm/versions/node/v10.15.3/bin/node:_ZN2v88internal17Builtin_JsonParseEiPPNS0_6ObjectEPNS0_7IsolateE
{
  // Load constants
  $kPointerSize = (uint32)(1 << (*uaddr("v8dbg_PointerSizeLog2")));
  $stringLengthOffset = (uint32)*uaddr("v8dbg_class_String__length__SMI");
  $kTag = (uint32)*uaddr("v8dbg_HeapObjectTag");
  $kTagMask = (uint32)*uaddr("v8dbg_SmiTagMask");
  $kShiftSize = (uint32)*uaddr("v8dbg_SmiShiftSize");

  // Object**
  $args_objects = arg1;

  $index = (uint64)1;

  $a = ($args_objects - ($index * $kPointerSize));
  $str = (uint64)(*$a);

  $b = (uint64)($str - $kTag + $stringLengthOffset);
  $strLen = ((int64)*$b) >> ($kShiftSize + $kTagMask);
  @ = hist($strLen);
}

// Node.js v12.11.1
uprobe:/home/mmarchini/.nvm/versions/node/v12.11.1/bin/node:_ZN2v88internal17Builtin_JsonParseEiPmPNS0_7IsolateE
{
  // Load constants
  $kPointerSize = (uint32)(1 << (*uaddr("v8dbg_SystemPointerSizeLog2")));
  $stringLengthOffset = (uint32)*uaddr("v8dbg_class_String__length__int32_t");
  $kTag = (uint32)*uaddr("v8dbg_HeapObjectTag");
  $kTagMask = (uint32)*uaddr("v8dbg_SmiTagMask");
  $kShiftSize = (uint32)*uaddr("v8dbg_SmiShiftSize");

  // Object**
  $args_objects = arg1;

  $index = (uint64)1;

  $a = ($args_objects - ($index * $kPointerSize));
  $str = (uint64)(*$a);

  $b = (uint64)($str - $kTag + $stringLengthOffset);
  $strLen = ((int32)*$b);
  @ = hist($strLen);
}

v10-json-parse-size-type-check.bt

uprobe:/home/mmarchini/.nvm/versions/node/v10.15.3/bin/node:_ZN2v88internal17Builtin_JsonParseEiPPNS0_6ObjectEPNS0_7IsolateE
{
  // Load constants
  $kPointerSize = (uint32)(1 << (*uaddr("v8dbg_PointerSizeLog2")));
  $stringLengthOffset = (uint32)*uaddr("v8dbg_class_String__length__SMI");
  $kTag = (uint32)*uaddr("v8dbg_HeapObjectTag");
  $kTagMask = (uint32)*uaddr("v8dbg_SmiTagMask");
  $kShiftSize = (uint32)*uaddr("v8dbg_SmiShiftSize");

  // 6 means only the string was given, 7 means a receiver was given as well.
  // Other numbers mean an invalid signature was used

  // int
  $args_length = arg0;
  // Object**
  $args_objects = arg1;
  // Isolate*, Probably not needed;
  $isolate = arg2;

  $index = (uint64)1;
  @l[$args_length] = count();

  $a = ($args_objects - ($index * $kPointerSize));
  $str = (uint64)(*$a);

  $kHTagMask = (uint32)*uaddr("v8dbg_HeapObjectTagMask");
  $kMapOffset = (uint32)*uaddr("v8dbg_class_HeapObject__map__Map");
  $kMapTypeOffset = (uint32)*uaddr("v8dbg_class_Map__instance_type__uint16_t");
  $kMapTypeMask = (uint32)0xffff;
  $kFirstNonstringType = (uint32)*uaddr("v8dbg_FirstNonstringType");
  $map = $str + $kMapOffset;

  if ((($str & $kHTagMask) == $kTag) && (($map & $kHTagMask) == $kTag)) {
    $typeAddr = $map + $kMapTypeOffset;
    $type = *$typeAddr;
    $type = $type & $kMapTypeMask;

    if ($type < $kFirstNonstringType) {
      $b = (uint64)($str - $kTag + $stringLengthOffset);
      $strLen = ((int64)*$b) >> ($kShiftSize + $kTagMask);
      @ = hist($strLen);
    } else {
      @miss[0] = count();
      printf("%lx %lx %lx %lx\n", $map, $typeAddr, $type, $kFirstNonstringType);
      printf("%s\n", ustack);
    }
  } else {
    @miss[1] = count();
  }
}