gold/attributes.cc

   1 // attributes.cc -- object attributes for gold
   2
   3 // Copyright (C) 2009-2019 Free Software Foundation, Inc.
   4 // Written by Doug Kwan <dougkwan@google.com>.
   5 // This file contains code adapted from BFD.
   6
   7 // This file is part of gold.
   8
   9 // This program is free software; you can redistribute it and/or modify
  10 // it under the terms of the GNU General Public License as published by
  11 // the Free Software Foundation; either version 3 of the License, or
  12 // (at your option) any later version.
  13
  14 // This program is distributed in the hope that it will be useful,
  15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 // GNU General Public License for more details.
  18
  19 // You should have received a copy of the GNU General Public License
  20 // along with this program; if not, write to the Free Software
  21 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  22 // MA 02110-1301, USA.
  23
  24 #include "gold.h"
  25
  26 #include <limits>
  27
  28 #include "attributes.h"
  29 #include "elfcpp.h"
  30 #include "target.h"
  31 #include "parameters.h"
  32 #include "int_encoding.h"
  33
  34 namespace gold
  35 {
  36
  37 // Object_attribute methods.
  38
  39 // Return size of attribute encode in ULEB128.
  40
  41 size_t
  42 Object_attribute::size(int tag) const
  43 {
  44   // Attributes with default values are not written out.
  45   if (this->is_default_attribute())
  46     return 0;
  47
  48   size_t size = get_length_as_unsigned_LEB_128(tag);
  49   if (Object_attribute::attribute_type_has_int_value(this->type_))
  50     size += get_length_as_unsigned_LEB_128(this->int_value_);
  51   if (Object_attribute::attribute_type_has_string_value(this->type_))
  52     size += this->string_value_.size() + 1;
  53   return size;
  54 }
  55
  56 // Whether this has the default value (0/"").
  57
  58 bool
  59 Object_attribute::is_default_attribute() const
  60 {
  61   if (Object_attribute::attribute_type_has_int_value(this->type_)
  62       && this->int_value_ != 0)
  63     return false;
  64   if (Object_attribute::attribute_type_has_string_value(this->type_)
  65       && !this->string_value_.empty())
  66     return false;
  67   if (Object_attribute::attribute_type_has_no_default(this->type_))
  68     return false;
  69
  70   return true;
  71 }
  72
  73 // Whether this matches another Object_attribute OA in merging.
  74 // Two Object_attributes match if they have the same values.
  75
  76 bool
  77 Object_attribute::matches(const Object_attribute& oa) const
  78 {
  79   return ((this->int_value_ != oa.int_value_)
  80           && (this->string_value_ == oa.string_value_));
  81 }
  82
  83 // Write this with TAG to a BUFFER.
  84
  85 void
  86 Object_attribute::write(
  87     int tag,
  88     std::vector<unsigned char>* buffer) const
  89 {
  90   // No need to write default attributes.
  91   if (this->is_default_attribute())
  92     return;
  93
  94   // Write tag.
  95   write_unsigned_LEB_128(buffer, convert_types<uint64_t, int>(tag));
  96
  97   // Write integer value.
  98   if (Object_attribute::attribute_type_has_int_value(this->type_))
  99     write_unsigned_LEB_128(buffer,
 100                            convert_types<uint64_t, int>(this->int_value_));
 101
 102   // Write string value.
 103   if (Object_attribute::attribute_type_has_string_value(this->type_))
 104     {
 105       const unsigned char* start =
 106         reinterpret_cast<const unsigned char*>(this->string_value_.c_str());
 107       const unsigned char* end = start + this->string_value_.size() + 1;
 108       buffer->insert(buffer->end(), start, end);
 109     }
 110 }
 111
 112 // Vendor_object_attributes methods.
 113
 114 // Copying constructor.
 115
 116 Vendor_object_attributes::Vendor_object_attributes(
 117     const Vendor_object_attributes& voa)
 118 {
 119   this->vendor_ = voa.vendor_;
 120
 121   for (int i = 0; i < NUM_KNOWN_ATTRIBUTES; ++i)
 122     this->known_attributes_[i] = voa.known_attributes_[i];
 123
 124   // We do not handle attribute deletion.  So this must be empty.
 125   gold_assert(this->other_attributes_.empty());
 126
 127   for (Other_attributes::const_iterator p = voa.other_attributes_.begin();
 128        p != voa.other_attributes_.end();
 129        ++p)
 130     this->other_attributes_[p->first] = new Object_attribute(*(p->second));
 131 }
 132
 133 // Size of this in number of bytes.
 134
 135 size_t
 136 Vendor_object_attributes::size() const
 137 {
 138   if (this->name() == NULL)
 139     return 0;
 140
 141   size_t data_size = 0;
 142   for (int i = 4; i < NUM_KNOWN_ATTRIBUTES; ++i)
 143     data_size += this->known_attributes_[i].size(i);
 144
 145   for (Other_attributes::const_iterator p = this->other_attributes_.begin();
 146        p != this->other_attributes_.end();
 147        ++p)
 148     data_size += p->second->size(p->first);
 149
 150   // <size> <vendor_name> NUL 0x1 <size>
 151   return ((data_size != 0
 152            || this->vendor_ == Object_attribute::OBJ_ATTR_PROC)
 153           ? data_size + strlen(this->name()) + 2 + 2 * 4
 154           : 0);
 155 }
 156
 157 // Return a new attribute associated with TAG.
 158
 159 Object_attribute*
 160 Vendor_object_attributes::new_attribute(int tag)
 161 {
 162   int type = Object_attribute::arg_type(this->vendor_, tag);
 163
 164   if (tag < NUM_KNOWN_ATTRIBUTES)
 165     {
 166       this->known_attributes_[tag].set_type(type);
 167       return &this->known_attributes_[tag];
 168     }
 169   else
 170     {
 171       Object_attribute* attr = new Object_attribute();
 172
 173       // This should be the first time we insert this.
 174       std::pair<Other_attributes::iterator, bool> ins =
 175         this->other_attributes_.insert(std::make_pair(tag, attr));
 176       gold_assert(ins.second);
 177
 178       attr->set_type(type);
 179       return attr;
 180     }
 181 }
 182
 183 // Return an attribute associated with TAG.
 184
 185 Object_attribute*
 186 Vendor_object_attributes::get_attribute(int tag)
 187 {
 188   if (tag < NUM_KNOWN_ATTRIBUTES)
 189     return &this->known_attributes_[tag];
 190   else
 191     {
 192       Other_attributes::iterator p =
 193         this->other_attributes_.find(tag);
 194       return p != this->other_attributes_.end() ? p->second : NULL;
 195     }
 196 }
 197
 198 const Object_attribute*
 199 Vendor_object_attributes::get_attribute(int tag) const
 200 {
 201   if (tag < NUM_KNOWN_ATTRIBUTES)
 202     return &this->known_attributes_[tag];
 203   else
 204     {
 205       Other_attributes::const_iterator p =
 206         this->other_attributes_.find(tag);
 207       return p != this->other_attributes_.end() ? p->second : NULL;
 208     }
 209 }
 210
 211 // Write attributes to BUFFER.
 212
 213 void
 214 Vendor_object_attributes::write(std::vector<unsigned char>* buffer) const
 215 {
 216   // Write subsection size.
 217   size_t voa_size = this->size();
 218   uint32_t voa_size_as_u32 = convert_types<uint32_t, size_t>(voa_size);
 219   insert_into_vector<32>(buffer, voa_size_as_u32);
 220
 221   // Write vendor name.
 222   const unsigned char* vendor_start =
 223     reinterpret_cast<const unsigned char*>(this->name());
 224   size_t vendor_length = strlen(this->name()) + 1;
 225   const unsigned char* vendor_end = vendor_start + vendor_length;
 226   buffer->insert(buffer->end(), vendor_start, vendor_end);
 227
 228   // Write file tag.
 229   buffer->push_back(Object_attribute::Tag_File);
 230
 231   // Write attributes size.
 232   uint32_t attributes_size_as_u32 =
 233     convert_types<uint32_t, size_t>(voa_size - 4 - vendor_length);
 234   insert_into_vector<32>(buffer, attributes_size_as_u32);
 235
 236   // Write known attributes, skipping any defaults.
 237   for (int i = 4; i < NUM_KNOWN_ATTRIBUTES; ++i)
 238     {
 239       // A target may write known attributes in a special order.
 240       // Call target hook to remap tags.  Attributes_order is the identity
 241       // function if no re-ordering is required.
 242       int tag = parameters->target().attributes_order(i);
 243       this->known_attributes_[tag].write(tag, buffer);
 244     }
 245
 246   // Write other attributes.
 247   for (Other_attributes::const_iterator q = this->other_attributes_.begin();
 248        q != this->other_attributes_.end();
 249        ++q)
 250     q->second->write(q->first, buffer);
 251 }
 252
 253 // Attributes_section_data methods.
 254
 255 // Compute encoded size of this.
 256
 257 size_t
 258 Attributes_section_data::size() const
 259 {
 260   size_t data_size = 0;
 261   for(int vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; ++vendor)
 262     data_size += this->vendor_object_attributes_[vendor]->size();
 263
 264   // 'A' <sections for each vendor>
 265   return data_size != 0 ? data_size + 1 : 0;
 266 }
 267
 268 // Construct an Attributes_section_data object by parsing section contents
 269 // specified by VIEW and SIZE.
 270
 271 Attributes_section_data::Attributes_section_data(
 272     const unsigned char* view,
 273     section_size_type size)
 274 {
 275   for (int vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; ++vendor)
 276     this->vendor_object_attributes_[vendor] =
 277       new Vendor_object_attributes(vendor);
 278
 279   const unsigned char* p = view;
 280   p = view;
 281   if (size > 0 && p != NULL && *(p++) == 'A')
 282     {
 283       size--;
 284       while (size > 0)
 285         {
 286           // Size of vendor attributes section.
 287           section_size_type section_size =
 288             convert_to_section_size_type(read_from_pointer<32>(&p));
 289
 290           if (section_size > size)
 291             section_size = size;
 292           size -= section_size;
 293
 294           const char* section_name = reinterpret_cast<const char*>(p);
 295           section_size_type section_name_size = strlen(section_name) + 1;
 296           section_size -= section_name_size + 4;
 297
 298           int vendor;
 299           const char* std_section = parameters->target().attributes_vendor();
 300           if (std_section != NULL && strcmp(section_name, std_section) == 0)
 301             vendor = Object_attribute::OBJ_ATTR_PROC;
 302           else if (strcmp(section_name, "gnu") == 0)
 303             vendor = Object_attribute::OBJ_ATTR_GNU;
 304           else
 305             {
 306               // Other vendor section.  Ignore it.
 307               p += section_name_size + section_size;
 308               continue;
 309             }
 310           p += section_name_size;
 311
 312           while (section_size > 0)
 313             {
 314               const unsigned char* subsection_start = p;
 315
 316               // Read vendor subsection index and size.
 317               size_t uleb128_len;
 318               uint64_t val = read_unsigned_LEB_128(p, &uleb128_len);
 319               p += uleb128_len;
 320
 321               int tag = convert_types<int, uint64_t>(val);
 322               section_size_type subsection_size =
 323                 convert_to_section_size_type(read_from_pointer<32>(&p));
 324               section_size -= subsection_size;
 325               subsection_size -= (p - subsection_start);
 326
 327               const unsigned char* end = p + subsection_size;
 328               switch (tag)
 329                 {
 330                 case Object_attribute::Tag_File:
 331                   while (p < end)
 332                     {
 333                       val = read_unsigned_LEB_128(p, &uleb128_len);
 334                       p += uleb128_len;
 335                       tag = convert_types<int, uint64_t>(val);
 336                       Vendor_object_attributes* pvoa =
 337                         this->vendor_object_attributes_[vendor];
 338                       Object_attribute* attr = pvoa->new_attribute(tag);
 339                       const char* string_arg;
 340                       unsigned int int_arg;
 341
 342                       int type = Object_attribute::arg_type(vendor, tag);
 343                       switch (type
 344                               & (Object_attribute::ATTR_TYPE_FLAG_INT_VAL
 345                                  | Object_attribute::ATTR_TYPE_FLAG_STR_VAL))
 346                         {
 347                         case (Object_attribute::ATTR_TYPE_FLAG_INT_VAL
 348                               | Object_attribute::ATTR_TYPE_FLAG_STR_VAL):
 349                           val = read_unsigned_LEB_128(p, &uleb128_len);
 350                           p += uleb128_len;
 351                           int_arg = convert_types<unsigned int, uint64_t>(val);
 352                           string_arg = reinterpret_cast<const char *>(p);
 353                           attr->set_int_value(int_arg);
 354                           p += strlen(string_arg) + 1;
 355                           break;
 356                         case Object_attribute::ATTR_TYPE_FLAG_STR_VAL:
 357                           string_arg = reinterpret_cast<const char *>(p);
 358                           attr->set_string_value(string_arg);
 359                           p += strlen(string_arg) + 1;
 360                           break;
 361                         case Object_attribute::ATTR_TYPE_FLAG_INT_VAL:
 362                           val = read_unsigned_LEB_128(p, &uleb128_len);
 363                           p += uleb128_len;
 364                           int_arg = convert_types<unsigned int, uint64_t>(val);
 365                           attr->set_int_value(int_arg);
 366                           break;
 367                         default:
 368                           gold_unreachable();
 369                         }
 370                     }
 371                   break;
 372                 case Object_attribute::Tag_Section:
 373                 case Object_attribute::Tag_Symbol:
 374                   // Don't have anywhere convenient to attach these.
 375                   // Fall through for now.
 376                 default:
 377                   // Ignore things we don't know about.
 378                   p += subsection_size;
 379                   subsection_size = 0;
 380                   break;
 381                 }
 382             }
 383         }
 384     }
 385 }
 386
 387 // Merge target-independent attributes from another Attribute_section_data
 388 // ASD from an object called NAME into this.
 389
 390 void
 391 Attributes_section_data::merge(
 392     const char* name,
 393     const Attributes_section_data* pasd)
 394 {
 395   // The only common attribute is currently Tag_compatibility,
 396   // accepted in both processor and "gnu" sections.
 397   for (int vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; ++vendor)
 398     {
 399       // Handle Tag_compatibility.  The tags are only compatible if the flags
 400       // are identical and, if the flags are '1', the strings are identical.
 401       // If the flags are non-zero, then we can only use the string "gnu".
 402       const Object_attribute* in_attr =
 403         &pasd->known_attributes(vendor)[Object_attribute::Tag_compatibility];
 404       Object_attribute* out_attr =
 405         &this->known_attributes(vendor)[Object_attribute::Tag_compatibility];
 406
 407       if (in_attr->int_value() > 0
 408           && in_attr->string_value() != "gnu")
 409         {
 410           gold_error(_("%s: must be processed by '%s' toolchain"),
 411                      name, in_attr->string_value().c_str());
 412           return;
 413         }
 414
 415       if (in_attr->int_value() != out_attr->int_value()
 416           || in_attr->string_value() != out_attr->string_value())
 417         {
 418           gold_error(_("%s: object tag '%d, %s' is "
 419                        "incompatible with tag '%d, %s'"),
 420                      name, in_attr->int_value(),
 421                      in_attr->string_value().c_str(),
 422                      out_attr->int_value(),
 423                      out_attr->string_value().c_str());
 424         }
 425     }
 426 }
 427
 428 // Write to a buffer.
 429
 430 void
 431 Attributes_section_data::write(std::vector<unsigned char>* buffer) const
 432 {
 433   buffer->push_back('A');
 434   for (int vendor = OBJ_ATTR_FIRST; vendor <= OBJ_ATTR_LAST; ++vendor)
 435     if (this->vendor_object_attributes_[vendor]->size() != 0)
 436       this->vendor_object_attributes_[vendor]->write(buffer);
 437 }
 438
 439 // Methods for Output_attributes_section_data.
 440
 441 // Write attributes section data to file OF.
 442
 443 void
 444 Output_attributes_section_data::do_write(Output_file* of)
 445 {
 446   off_t offset = this->offset();
 447   const section_size_type oview_size =
 448     convert_to_section_size_type(this->data_size());
 449   unsigned char* const oview = of->get_output_view(offset, oview_size);
 450
 451   std::vector<unsigned char> buffer;
 452   this->attributes_section_data_.write(&buffer);
 453   gold_assert(convert_to_section_size_type(buffer.size()) == oview_size);
 454   memcpy(oview, &buffer.front(), buffer.size());
 455   of->write_output_view(this->offset(), oview_size, oview);
 456 }
 457
 458 } // End namespace gold.