1 //===-- DWARFCallFrameInfo.cpp ----------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 11 // C Includes 12 // C++ Includes 13 #include <list> 14 15 #include "lldb/Core/Log.h" 16 #include "lldb/Core/Section.h" 17 #include "lldb/Core/ArchSpec.h" 18 #include "lldb/Core/Module.h" 19 #include "lldb/Core/Section.h" 20 #include "lldb/Core/Timer.h" 21 #include "lldb/Host/Host.h" 22 #include "lldb/Symbol/DWARFCallFrameInfo.h" 23 #include "lldb/Symbol/ObjectFile.h" 24 #include "lldb/Symbol/UnwindPlan.h" 25 #include "lldb/Target/RegisterContext.h" 26 #include "lldb/Target/Thread.h" 27 28 using namespace lldb; 29 using namespace lldb_private; 30 31 DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile& objfile, SectionSP& section_sp, lldb::RegisterKind reg_kind, bool is_eh_frame) : 32 m_objfile (objfile), 33 m_section_sp (section_sp), 34 m_reg_kind (reg_kind), // The flavor of registers that the CFI data uses (enum RegisterKind) 35 m_flags (), 36 m_cie_map (), 37 m_cfi_data (), 38 m_cfi_data_initialized (false), 39 m_fde_index (), 40 m_fde_index_initialized (false), 41 m_is_eh_frame (is_eh_frame) 42 { 43 } 44 45 DWARFCallFrameInfo::~DWARFCallFrameInfo() 46 { 47 } 48 49 50 bool 51 DWARFCallFrameInfo::GetUnwindPlan (Address addr, UnwindPlan& unwind_plan) 52 { 53 FDEEntryMap::Entry fde_entry; 54 55 // Make sure that the Address we're searching for is the same object file 56 // as this DWARFCallFrameInfo, we only store File offsets in m_fde_index. 57 ModuleSP module_sp = addr.GetModule(); 58 if (module_sp.get() == NULL || module_sp->GetObjectFile() == NULL || module_sp->GetObjectFile() != &m_objfile) 59 return false; 60 61 if (GetFDEEntryByFileAddress (addr.GetFileAddress(), fde_entry) == false) 62 return false; 63 return FDEToUnwindPlan (fde_entry.data, addr, unwind_plan); 64 } 65 66 bool 67 DWARFCallFrameInfo::GetAddressRange (Address addr, AddressRange &range) 68 { 69 70 // Make sure that the Address we're searching for is the same object file 71 // as this DWARFCallFrameInfo, we only store File offsets in m_fde_index. 72 ModuleSP module_sp = addr.GetModule(); 73 if (module_sp.get() == NULL || module_sp->GetObjectFile() == NULL || module_sp->GetObjectFile() != &m_objfile) 74 return false; 75 76 if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted()) 77 return false; 78 GetFDEIndex(); 79 FDEEntryMap::Entry *fde_entry = m_fde_index.FindEntryThatContains (addr.GetFileAddress()); 80 if (!fde_entry) 81 return false; 82 83 range = AddressRange(fde_entry->base, fde_entry->size, m_objfile.GetSectionList()); 84 return true; 85 } 86 87 bool 88 DWARFCallFrameInfo::GetFDEEntryByFileAddress (addr_t file_addr, FDEEntryMap::Entry &fde_entry) 89 { 90 if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted()) 91 return false; 92 93 GetFDEIndex(); 94 95 if (m_fde_index.IsEmpty()) 96 return false; 97 98 FDEEntryMap::Entry *fde = m_fde_index.FindEntryThatContains (file_addr); 99 100 if (fde == NULL) 101 return false; 102 103 fde_entry = *fde; 104 return true; 105 } 106 107 void 108 DWARFCallFrameInfo::GetFunctionAddressAndSizeVector (FunctionAddressAndSizeVector &function_info) 109 { 110 GetFDEIndex(); 111 const size_t count = m_fde_index.GetSize(); 112 function_info.Clear(); 113 if (count > 0) 114 function_info.Reserve(count); 115 for (size_t i = 0; i < count; ++i) 116 { 117 const FDEEntryMap::Entry *func_offset_data_entry = m_fde_index.GetEntryAtIndex (i); 118 if (func_offset_data_entry) 119 { 120 FunctionAddressAndSizeVector::Entry function_offset_entry (func_offset_data_entry->base, func_offset_data_entry->size); 121 function_info.Append (function_offset_entry); 122 } 123 } 124 } 125 126 const DWARFCallFrameInfo::CIE* 127 DWARFCallFrameInfo::GetCIE(dw_offset_t cie_offset) 128 { 129 cie_map_t::iterator pos = m_cie_map.find(cie_offset); 130 131 if (pos != m_cie_map.end()) 132 { 133 // Parse and cache the CIE 134 if (pos->second.get() == NULL) 135 pos->second = ParseCIE (cie_offset); 136 137 return pos->second.get(); 138 } 139 return NULL; 140 } 141 142 DWARFCallFrameInfo::CIESP 143 DWARFCallFrameInfo::ParseCIE (const dw_offset_t cie_offset) 144 { 145 CIESP cie_sp(new CIE(cie_offset)); 146 lldb::offset_t offset = cie_offset; 147 if (m_cfi_data_initialized == false) 148 GetCFIData(); 149 const uint32_t length = m_cfi_data.GetU32(&offset); 150 const dw_offset_t cie_id = m_cfi_data.GetU32(&offset); 151 const dw_offset_t end_offset = cie_offset + length + 4; 152 if (length > 0 && ((!m_is_eh_frame && cie_id == UINT32_MAX) || (m_is_eh_frame && cie_id == 0ul))) 153 { 154 size_t i; 155 // cie.offset = cie_offset; 156 // cie.length = length; 157 // cie.cieID = cieID; 158 cie_sp->ptr_encoding = DW_EH_PE_absptr; // default 159 cie_sp->version = m_cfi_data.GetU8(&offset); 160 161 for (i=0; i<CFI_AUG_MAX_SIZE; ++i) 162 { 163 cie_sp->augmentation[i] = m_cfi_data.GetU8(&offset); 164 if (cie_sp->augmentation[i] == '\0') 165 { 166 // Zero out remaining bytes in augmentation string 167 for (size_t j = i+1; j<CFI_AUG_MAX_SIZE; ++j) 168 cie_sp->augmentation[j] = '\0'; 169 170 break; 171 } 172 } 173 174 if (i == CFI_AUG_MAX_SIZE && cie_sp->augmentation[CFI_AUG_MAX_SIZE-1] != '\0') 175 { 176 Host::SystemLog (Host::eSystemLogError, "CIE parse error: CIE augmentation string was too large for the fixed sized buffer of %d bytes.\n", CFI_AUG_MAX_SIZE); 177 return cie_sp; 178 } 179 cie_sp->code_align = (uint32_t)m_cfi_data.GetULEB128(&offset); 180 cie_sp->data_align = (int32_t)m_cfi_data.GetSLEB128(&offset); 181 cie_sp->return_addr_reg_num = m_cfi_data.GetU8(&offset); 182 183 if (cie_sp->augmentation[0]) 184 { 185 // Get the length of the eh_frame augmentation data 186 // which starts with a ULEB128 length in bytes 187 const size_t aug_data_len = (size_t)m_cfi_data.GetULEB128(&offset); 188 const size_t aug_data_end = offset + aug_data_len; 189 const size_t aug_str_len = strlen(cie_sp->augmentation); 190 // A 'z' may be present as the first character of the string. 191 // If present, the Augmentation Data field shall be present. 192 // The contents of the Augmentation Data shall be intepreted 193 // according to other characters in the Augmentation String. 194 if (cie_sp->augmentation[0] == 'z') 195 { 196 // Extract the Augmentation Data 197 size_t aug_str_idx = 0; 198 for (aug_str_idx = 1; aug_str_idx < aug_str_len; aug_str_idx++) 199 { 200 char aug = cie_sp->augmentation[aug_str_idx]; 201 switch (aug) 202 { 203 case 'L': 204 // Indicates the presence of one argument in the 205 // Augmentation Data of the CIE, and a corresponding 206 // argument in the Augmentation Data of the FDE. The 207 // argument in the Augmentation Data of the CIE is 208 // 1-byte and represents the pointer encoding used 209 // for the argument in the Augmentation Data of the 210 // FDE, which is the address of a language-specific 211 // data area (LSDA). The size of the LSDA pointer is 212 // specified by the pointer encoding used. 213 m_cfi_data.GetU8(&offset); 214 break; 215 216 case 'P': 217 // Indicates the presence of two arguments in the 218 // Augmentation Data of the cie_sp-> The first argument 219 // is 1-byte and represents the pointer encoding 220 // used for the second argument, which is the 221 // address of a personality routine handler. The 222 // size of the personality routine pointer is 223 // specified by the pointer encoding used. 224 { 225 uint8_t arg_ptr_encoding = m_cfi_data.GetU8(&offset); 226 m_cfi_data.GetGNUEHPointer(&offset, arg_ptr_encoding, LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS); 227 } 228 break; 229 230 case 'R': 231 // A 'R' may be present at any position after the 232 // first character of the string. The Augmentation 233 // Data shall include a 1 byte argument that 234 // represents the pointer encoding for the address 235 // pointers used in the FDE. 236 // Example: 0x1B == DW_EH_PE_pcrel | DW_EH_PE_sdata4 237 cie_sp->ptr_encoding = m_cfi_data.GetU8(&offset); 238 break; 239 } 240 } 241 } 242 else if (strcmp(cie_sp->augmentation, "eh") == 0) 243 { 244 // If the Augmentation string has the value "eh", then 245 // the EH Data field shall be present 246 } 247 248 // Set the offset to be the end of the augmentation data just in case 249 // we didn't understand any of the data. 250 offset = (uint32_t)aug_data_end; 251 } 252 253 if (end_offset > offset) 254 { 255 cie_sp->inst_offset = offset; 256 cie_sp->inst_length = end_offset - offset; 257 } 258 while (offset < end_offset) 259 { 260 uint8_t inst = m_cfi_data.GetU8(&offset); 261 uint8_t primary_opcode = inst & 0xC0; 262 uint8_t extended_opcode = inst & 0x3F; 263 264 if (extended_opcode == DW_CFA_def_cfa) 265 { 266 // Takes two unsigned LEB128 operands representing a register 267 // number and a (non-factored) offset. The required action 268 // is to define the current CFA rule to use the provided 269 // register and offset. 270 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 271 int op_offset = (int32_t)m_cfi_data.GetULEB128(&offset); 272 cie_sp->initial_row.SetCFARegister (reg_num); 273 cie_sp->initial_row.SetCFAOffset (op_offset); 274 continue; 275 } 276 if (primary_opcode == DW_CFA_offset) 277 { 278 // 0x80 - high 2 bits are 0x2, lower 6 bits are register. 279 // Takes two arguments: an unsigned LEB128 constant representing a 280 // factored offset and a register number. The required action is to 281 // change the rule for the register indicated by the register number 282 // to be an offset(N) rule with a value of 283 // (N = factored offset * data_align). 284 uint32_t reg_num = extended_opcode; 285 int op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * cie_sp->data_align; 286 UnwindPlan::Row::RegisterLocation reg_location; 287 reg_location.SetAtCFAPlusOffset(op_offset); 288 cie_sp->initial_row.SetRegisterInfo (reg_num, reg_location); 289 continue; 290 } 291 if (extended_opcode == DW_CFA_nop) 292 { 293 continue; 294 } 295 break; // Stop if we hit an unrecognized opcode 296 } 297 } 298 299 return cie_sp; 300 } 301 302 void 303 DWARFCallFrameInfo::GetCFIData() 304 { 305 if (m_cfi_data_initialized == false) 306 { 307 Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND)); 308 if (log) 309 m_objfile.GetModule()->LogMessage(log, "Reading EH frame info"); 310 m_objfile.ReadSectionData (m_section_sp.get(), m_cfi_data); 311 m_cfi_data_initialized = true; 312 } 313 } 314 // Scan through the eh_frame or debug_frame section looking for FDEs and noting the start/end addresses 315 // of the functions and a pointer back to the function's FDE for later expansion. 316 // Internalize CIEs as we come across them. 317 318 void 319 DWARFCallFrameInfo::GetFDEIndex () 320 { 321 if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted()) 322 return; 323 324 if (m_fde_index_initialized) 325 return; 326 327 Mutex::Locker locker(m_fde_index_mutex); 328 329 if (m_fde_index_initialized) // if two threads hit the locker 330 return; 331 332 Timer scoped_timer (__PRETTY_FUNCTION__, "%s - %s", __PRETTY_FUNCTION__, m_objfile.GetFileSpec().GetFilename().AsCString("")); 333 334 lldb::offset_t offset = 0; 335 if (m_cfi_data_initialized == false) 336 GetCFIData(); 337 while (m_cfi_data.ValidOffsetForDataOfSize (offset, 8)) 338 { 339 const dw_offset_t current_entry = offset; 340 uint32_t len = m_cfi_data.GetU32 (&offset); 341 dw_offset_t next_entry = current_entry + len + 4; 342 dw_offset_t cie_id = m_cfi_data.GetU32 (&offset); 343 344 if (cie_id == 0 || cie_id == UINT32_MAX) 345 { 346 m_cie_map[current_entry] = ParseCIE (current_entry); 347 offset = next_entry; 348 continue; 349 } 350 351 const dw_offset_t cie_offset = current_entry + 4 - cie_id; 352 const CIE *cie = GetCIE (cie_offset); 353 if (cie) 354 { 355 const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress(); 356 const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS; 357 const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS; 358 359 lldb::addr_t addr = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding, pc_rel_addr, text_addr, data_addr); 360 lldb::addr_t length = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING, pc_rel_addr, text_addr, data_addr); 361 FDEEntryMap::Entry fde (addr, length, current_entry); 362 m_fde_index.Append(fde); 363 } 364 else 365 { 366 Host::SystemLog (Host::eSystemLogError, 367 "error: unable to find CIE at 0x%8.8x for cie_id = 0x%8.8x for entry at 0x%8.8x.\n", 368 cie_offset, 369 cie_id, 370 current_entry); 371 } 372 offset = next_entry; 373 } 374 m_fde_index.Sort(); 375 m_fde_index_initialized = true; 376 } 377 378 bool 379 DWARFCallFrameInfo::FDEToUnwindPlan (dw_offset_t dwarf_offset, Address startaddr, UnwindPlan& unwind_plan) 380 { 381 lldb::offset_t offset = dwarf_offset; 382 lldb::offset_t current_entry = offset; 383 384 if (m_section_sp.get() == NULL || m_section_sp->IsEncrypted()) 385 return false; 386 387 if (m_cfi_data_initialized == false) 388 GetCFIData(); 389 390 uint32_t length = m_cfi_data.GetU32 (&offset); 391 dw_offset_t cie_offset = m_cfi_data.GetU32 (&offset); 392 393 assert (cie_offset != 0 && cie_offset != UINT32_MAX); 394 395 // Translate the CIE_id from the eh_frame format, which 396 // is relative to the FDE offset, into a __eh_frame section 397 // offset 398 if (m_is_eh_frame) 399 { 400 unwind_plan.SetSourceName ("eh_frame CFI"); 401 cie_offset = current_entry + 4 - cie_offset; 402 unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo); 403 } 404 else 405 { 406 unwind_plan.SetSourceName ("DWARF CFI"); 407 // In theory the debug_frame info should be valid at all call sites 408 // ("asynchronous unwind info" as it is sometimes called) but in practice 409 // gcc et al all emit call frame info for the prologue and call sites, but 410 // not for the epilogue or all the other locations during the function reliably. 411 unwind_plan.SetUnwindPlanValidAtAllInstructions (eLazyBoolNo); 412 } 413 unwind_plan.SetSourcedFromCompiler (eLazyBoolYes); 414 415 const CIE *cie = GetCIE (cie_offset); 416 assert (cie != NULL); 417 418 const dw_offset_t end_offset = current_entry + length + 4; 419 420 const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress(); 421 const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS; 422 const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS; 423 lldb::addr_t range_base = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding, pc_rel_addr, text_addr, data_addr); 424 lldb::addr_t range_len = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING, pc_rel_addr, text_addr, data_addr); 425 AddressRange range (range_base, m_objfile.GetAddressByteSize(), m_objfile.GetSectionList()); 426 range.SetByteSize (range_len); 427 428 if (cie->augmentation[0] == 'z') 429 { 430 uint32_t aug_data_len = (uint32_t)m_cfi_data.GetULEB128(&offset); 431 offset += aug_data_len; 432 } 433 434 uint32_t reg_num = 0; 435 int32_t op_offset = 0; 436 uint32_t code_align = cie->code_align; 437 int32_t data_align = cie->data_align; 438 439 unwind_plan.SetPlanValidAddressRange (range); 440 UnwindPlan::Row *cie_initial_row = new UnwindPlan::Row; 441 *cie_initial_row = cie->initial_row; 442 UnwindPlan::RowSP row(cie_initial_row); 443 444 unwind_plan.SetRegisterKind (m_reg_kind); 445 unwind_plan.SetReturnAddressRegister (cie->return_addr_reg_num); 446 447 UnwindPlan::Row::RegisterLocation reg_location; 448 while (m_cfi_data.ValidOffset(offset) && offset < end_offset) 449 { 450 uint8_t inst = m_cfi_data.GetU8(&offset); 451 uint8_t primary_opcode = inst & 0xC0; 452 uint8_t extended_opcode = inst & 0x3F; 453 454 if (primary_opcode) 455 { 456 switch (primary_opcode) 457 { 458 case DW_CFA_advance_loc : // (Row Creation Instruction) 459 { // 0x40 - high 2 bits are 0x1, lower 6 bits are delta 460 // takes a single argument that represents a constant delta. The 461 // required action is to create a new table row with a location 462 // value that is computed by taking the current entry's location 463 // value and adding (delta * code_align). All other 464 // values in the new row are initially identical to the current row. 465 unwind_plan.AppendRow(row); 466 UnwindPlan::Row *newrow = new UnwindPlan::Row; 467 *newrow = *row.get(); 468 row.reset (newrow); 469 row->SlideOffset(extended_opcode * code_align); 470 } 471 break; 472 473 case DW_CFA_offset : 474 { // 0x80 - high 2 bits are 0x2, lower 6 bits are register 475 // takes two arguments: an unsigned LEB128 constant representing a 476 // factored offset and a register number. The required action is to 477 // change the rule for the register indicated by the register number 478 // to be an offset(N) rule with a value of 479 // (N = factored offset * data_align). 480 reg_num = extended_opcode; 481 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align; 482 reg_location.SetAtCFAPlusOffset(op_offset); 483 row->SetRegisterInfo (reg_num, reg_location); 484 } 485 break; 486 487 case DW_CFA_restore : 488 { // 0xC0 - high 2 bits are 0x3, lower 6 bits are register 489 // takes a single argument that represents a register number. The 490 // required action is to change the rule for the indicated register 491 // to the rule assigned it by the initial_instructions in the CIE. 492 reg_num = extended_opcode; 493 // We only keep enough register locations around to 494 // unwind what is in our thread, and these are organized 495 // by the register index in that state, so we need to convert our 496 // GCC register number from the EH frame info, to a register index 497 498 if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num, reg_location)) 499 row->SetRegisterInfo (reg_num, reg_location); 500 } 501 break; 502 } 503 } 504 else 505 { 506 switch (extended_opcode) 507 { 508 case DW_CFA_nop : // 0x0 509 break; 510 511 case DW_CFA_set_loc : // 0x1 (Row Creation Instruction) 512 { 513 // DW_CFA_set_loc takes a single argument that represents an address. 514 // The required action is to create a new table row using the 515 // specified address as the location. All other values in the new row 516 // are initially identical to the current row. The new location value 517 // should always be greater than the current one. 518 unwind_plan.AppendRow(row); 519 UnwindPlan::Row *newrow = new UnwindPlan::Row; 520 *newrow = *row.get(); 521 row.reset (newrow); 522 row->SetOffset(m_cfi_data.GetPointer(&offset) - startaddr.GetFileAddress()); 523 } 524 break; 525 526 case DW_CFA_advance_loc1 : // 0x2 (Row Creation Instruction) 527 { 528 // takes a single uword argument that represents a constant delta. 529 // This instruction is identical to DW_CFA_advance_loc except for the 530 // encoding and size of the delta argument. 531 unwind_plan.AppendRow(row); 532 UnwindPlan::Row *newrow = new UnwindPlan::Row; 533 *newrow = *row.get(); 534 row.reset (newrow); 535 row->SlideOffset (m_cfi_data.GetU8(&offset) * code_align); 536 } 537 break; 538 539 case DW_CFA_advance_loc2 : // 0x3 (Row Creation Instruction) 540 { 541 // takes a single uword argument that represents a constant delta. 542 // This instruction is identical to DW_CFA_advance_loc except for the 543 // encoding and size of the delta argument. 544 unwind_plan.AppendRow(row); 545 UnwindPlan::Row *newrow = new UnwindPlan::Row; 546 *newrow = *row.get(); 547 row.reset (newrow); 548 row->SlideOffset (m_cfi_data.GetU16(&offset) * code_align); 549 } 550 break; 551 552 case DW_CFA_advance_loc4 : // 0x4 (Row Creation Instruction) 553 { 554 // takes a single uword argument that represents a constant delta. 555 // This instruction is identical to DW_CFA_advance_loc except for the 556 // encoding and size of the delta argument. 557 unwind_plan.AppendRow(row); 558 UnwindPlan::Row *newrow = new UnwindPlan::Row; 559 *newrow = *row.get(); 560 row.reset (newrow); 561 row->SlideOffset (m_cfi_data.GetU32(&offset) * code_align); 562 } 563 break; 564 565 case DW_CFA_offset_extended : // 0x5 566 { 567 // takes two unsigned LEB128 arguments representing a register number 568 // and a factored offset. This instruction is identical to DW_CFA_offset 569 // except for the encoding and size of the register argument. 570 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 571 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align; 572 reg_location.SetAtCFAPlusOffset(op_offset); 573 row->SetRegisterInfo (reg_num, reg_location); 574 } 575 break; 576 577 case DW_CFA_restore_extended : // 0x6 578 { 579 // takes a single unsigned LEB128 argument that represents a register 580 // number. This instruction is identical to DW_CFA_restore except for 581 // the encoding and size of the register argument. 582 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 583 if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0)->GetRegisterInfo(reg_num, reg_location)) 584 row->SetRegisterInfo (reg_num, reg_location); 585 } 586 break; 587 588 case DW_CFA_undefined : // 0x7 589 { 590 // takes a single unsigned LEB128 argument that represents a register 591 // number. The required action is to set the rule for the specified 592 // register to undefined. 593 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 594 reg_location.SetUndefined(); 595 row->SetRegisterInfo (reg_num, reg_location); 596 } 597 break; 598 599 case DW_CFA_same_value : // 0x8 600 { 601 // takes a single unsigned LEB128 argument that represents a register 602 // number. The required action is to set the rule for the specified 603 // register to same value. 604 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 605 reg_location.SetSame(); 606 row->SetRegisterInfo (reg_num, reg_location); 607 } 608 break; 609 610 case DW_CFA_register : // 0x9 611 { 612 // takes two unsigned LEB128 arguments representing register numbers. 613 // The required action is to set the rule for the first register to be 614 // the second register. 615 616 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 617 uint32_t other_reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 618 reg_location.SetInRegister(other_reg_num); 619 row->SetRegisterInfo (reg_num, reg_location); 620 } 621 break; 622 623 case DW_CFA_remember_state : // 0xA 624 { 625 // These instructions define a stack of information. Encountering the 626 // DW_CFA_remember_state instruction means to save the rules for every 627 // register on the current row on the stack. Encountering the 628 // DW_CFA_restore_state instruction means to pop the set of rules off 629 // the stack and place them in the current row. (This operation is 630 // useful for compilers that move epilogue code into the body of a 631 // function.) 632 unwind_plan.AppendRow (row); 633 UnwindPlan::Row *newrow = new UnwindPlan::Row; 634 *newrow = *row.get(); 635 row.reset (newrow); 636 } 637 break; 638 639 case DW_CFA_restore_state : // 0xB 640 // These instructions define a stack of information. Encountering the 641 // DW_CFA_remember_state instruction means to save the rules for every 642 // register on the current row on the stack. Encountering the 643 // DW_CFA_restore_state instruction means to pop the set of rules off 644 // the stack and place them in the current row. (This operation is 645 // useful for compilers that move epilogue code into the body of a 646 // function.) 647 { 648 row = unwind_plan.GetRowAtIndex(unwind_plan.GetRowCount() - 1); 649 } 650 break; 651 652 case DW_CFA_def_cfa : // 0xC (CFA Definition Instruction) 653 { 654 // Takes two unsigned LEB128 operands representing a register 655 // number and a (non-factored) offset. The required action 656 // is to define the current CFA rule to use the provided 657 // register and offset. 658 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 659 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset); 660 row->SetCFARegister (reg_num); 661 row->SetCFAOffset (op_offset); 662 } 663 break; 664 665 case DW_CFA_def_cfa_register : // 0xD (CFA Definition Instruction) 666 { 667 // takes a single unsigned LEB128 argument representing a register 668 // number. The required action is to define the current CFA rule to 669 // use the provided register (but to keep the old offset). 670 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 671 row->SetCFARegister (reg_num); 672 } 673 break; 674 675 case DW_CFA_def_cfa_offset : // 0xE (CFA Definition Instruction) 676 { 677 // Takes a single unsigned LEB128 operand representing a 678 // (non-factored) offset. The required action is to define 679 // the current CFA rule to use the provided offset (but 680 // to keep the old register). 681 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset); 682 row->SetCFAOffset (op_offset); 683 } 684 break; 685 686 case DW_CFA_def_cfa_expression : // 0xF (CFA Definition Instruction) 687 { 688 size_t block_len = (size_t)m_cfi_data.GetULEB128(&offset); 689 offset += (uint32_t)block_len; 690 } 691 break; 692 693 case DW_CFA_expression : // 0x10 694 { 695 // Takes two operands: an unsigned LEB128 value representing 696 // a register number, and a DW_FORM_block value representing a DWARF 697 // expression. The required action is to change the rule for the 698 // register indicated by the register number to be an expression(E) 699 // rule where E is the DWARF expression. That is, the DWARF 700 // expression computes the address. The value of the CFA is 701 // pushed on the DWARF evaluation stack prior to execution of 702 // the DWARF expression. 703 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 704 uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset); 705 const uint8_t *block_data = (uint8_t *)m_cfi_data.GetData(&offset, block_len); 706 707 reg_location.SetAtDWARFExpression(block_data, block_len); 708 row->SetRegisterInfo (reg_num, reg_location); 709 } 710 break; 711 712 case DW_CFA_offset_extended_sf : // 0x11 713 { 714 // takes two operands: an unsigned LEB128 value representing a 715 // register number and a signed LEB128 factored offset. This 716 // instruction is identical to DW_CFA_offset_extended except 717 //that the second operand is signed and factored. 718 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 719 op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align; 720 reg_location.SetAtCFAPlusOffset(op_offset); 721 row->SetRegisterInfo (reg_num, reg_location); 722 } 723 break; 724 725 case DW_CFA_def_cfa_sf : // 0x12 (CFA Definition Instruction) 726 { 727 // Takes two operands: an unsigned LEB128 value representing 728 // a register number and a signed LEB128 factored offset. 729 // This instruction is identical to DW_CFA_def_cfa except 730 // that the second operand is signed and factored. 731 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 732 op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align; 733 row->SetCFARegister (reg_num); 734 row->SetCFAOffset (op_offset); 735 } 736 break; 737 738 case DW_CFA_def_cfa_offset_sf : // 0x13 (CFA Definition Instruction) 739 { 740 // takes a signed LEB128 operand representing a factored 741 // offset. This instruction is identical to DW_CFA_def_cfa_offset 742 // except that the operand is signed and factored. 743 op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align; 744 row->SetCFAOffset (op_offset); 745 } 746 break; 747 748 case DW_CFA_val_expression : // 0x16 749 { 750 // takes two operands: an unsigned LEB128 value representing a register 751 // number, and a DW_FORM_block value representing a DWARF expression. 752 // The required action is to change the rule for the register indicated 753 // by the register number to be a val_expression(E) rule where E is the 754 // DWARF expression. That is, the DWARF expression computes the value of 755 // the given register. The value of the CFA is pushed on the DWARF 756 // evaluation stack prior to execution of the DWARF expression. 757 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 758 uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset); 759 const uint8_t* block_data = (uint8_t*)m_cfi_data.GetData(&offset, block_len); 760 //#if defined(__i386__) || defined(__x86_64__) 761 // // The EH frame info for EIP and RIP contains code that looks for traps to 762 // // be a specific type and increments the PC. 763 // // For i386: 764 // // DW_CFA_val_expression where: 765 // // eip = DW_OP_breg6(+28), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x34), 766 // // DW_OP_deref, DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref, 767 // // DW_OP_dup, DW_OP_lit3, DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne, 768 // // DW_OP_and, DW_OP_plus 769 // // This basically does a: 770 // // eip = ucontenxt.mcontext32->gpr.eip; 771 // // if (ucontenxt.mcontext32->exc.trapno != 3 && ucontenxt.mcontext32->exc.trapno != 4) 772 // // eip++; 773 // // 774 // // For x86_64: 775 // // DW_CFA_val_expression where: 776 // // rip = DW_OP_breg3(+48), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x90), DW_OP_deref, 777 // // DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref_size(4), DW_OP_dup, DW_OP_lit3, 778 // // DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne, DW_OP_and, DW_OP_plus 779 // // This basically does a: 780 // // rip = ucontenxt.mcontext64->gpr.rip; 781 // // if (ucontenxt.mcontext64->exc.trapno != 3 && ucontenxt.mcontext64->exc.trapno != 4) 782 // // rip++; 783 // // The trap comparisons and increments are not needed as it hoses up the unwound PC which 784 // // is expected to point at least past the instruction that causes the fault/trap. So we 785 // // take it out by trimming the expression right at the first "DW_OP_swap" opcodes 786 // if (block_data != NULL && thread->GetPCRegNum(Thread::GCC) == reg_num) 787 // { 788 // if (thread->Is64Bit()) 789 // { 790 // if (block_len > 9 && block_data[8] == DW_OP_swap && block_data[9] == DW_OP_plus_uconst) 791 // block_len = 8; 792 // } 793 // else 794 // { 795 // if (block_len > 8 && block_data[7] == DW_OP_swap && block_data[8] == DW_OP_plus_uconst) 796 // block_len = 7; 797 // } 798 // } 799 //#endif 800 reg_location.SetIsDWARFExpression(block_data, block_len); 801 row->SetRegisterInfo (reg_num, reg_location); 802 } 803 break; 804 805 case DW_CFA_val_offset : // 0x14 806 case DW_CFA_val_offset_sf : // 0x15 807 default: 808 break; 809 } 810 } 811 } 812 unwind_plan.AppendRow(row); 813 814 return true; 815 } 816
