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/Symbol/DWARFCallFrameInfo.h" 18 #include "lldb/Core/ArchSpec.h" 19 #include "lldb/Core/Module.h" 20 #include "lldb/Symbol/ObjectFile.h" 21 #include "lldb/Target/RegisterContext.h" 22 #include "lldb/Core/Section.h" 23 #include "lldb/Target/Thread.h" 24 #include "lldb/Symbol/UnwindPlan.h" 25 26 using namespace lldb; 27 using namespace lldb_private; 28 29 DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile& objfile, SectionSP& section, uint32_t reg_kind, bool is_eh_frame) : 30 m_objfile (objfile), 31 m_section (section), 32 m_reg_kind (reg_kind), // The flavor of registers that the CFI data uses (enum RegisterKind) 33 m_flags (), 34 m_cie_map (), 35 m_cfi_data (), 36 m_cfi_data_initialized (false), 37 m_fde_index (), 38 m_fde_index_initialized (false), 39 m_is_eh_frame (is_eh_frame) 40 { 41 } 42 43 DWARFCallFrameInfo::~DWARFCallFrameInfo() 44 { 45 } 46 47 48 bool 49 DWARFCallFrameInfo::GetAddressRange (Address addr, AddressRange &range) 50 { 51 FDEEntry fde_entry; 52 if (GetFDEEntryByAddress (addr, fde_entry) == false) 53 return false; 54 range = fde_entry.bounds; 55 return true; 56 } 57 58 bool 59 DWARFCallFrameInfo::GetUnwindPlan (Address addr, UnwindPlan& unwind_plan) 60 { 61 FDEEntry fde_entry; 62 if (GetFDEEntryByAddress (addr, fde_entry) == false) 63 return false; 64 return FDEToUnwindPlan (fde_entry.offset, addr, unwind_plan); 65 } 66 67 bool 68 DWARFCallFrameInfo::GetFDEEntryByAddress (Address addr, FDEEntry& fde_entry) 69 { 70 if (m_section.get() == NULL || m_section->IsEncrypted()) 71 return false; 72 GetFDEIndex(); 73 74 struct FDEEntry searchfde; 75 searchfde.bounds = AddressRange (addr, 1); 76 77 std::vector<FDEEntry>::const_iterator idx; 78 if (m_fde_index.size() == 0) 79 return false; 80 81 idx = std::lower_bound (m_fde_index.begin(), m_fde_index.end(), searchfde); 82 if (idx == m_fde_index.end()) 83 { 84 --idx; 85 } 86 if (idx != m_fde_index.begin() && idx->bounds.GetBaseAddress().GetOffset() != addr.GetOffset()) 87 { 88 --idx; 89 } 90 if (idx->bounds.ContainsFileAddress (addr)) 91 { 92 fde_entry = *idx; 93 return true; 94 } 95 96 return false; 97 } 98 99 const DWARFCallFrameInfo::CIE* 100 DWARFCallFrameInfo::GetCIE(dw_offset_t cie_offset) 101 { 102 cie_map_t::iterator pos = m_cie_map.find(cie_offset); 103 104 if (pos != m_cie_map.end()) 105 { 106 // Parse and cache the CIE 107 if (pos->second.get() == NULL) 108 pos->second = ParseCIE (cie_offset); 109 110 return pos->second.get(); 111 } 112 return NULL; 113 } 114 115 DWARFCallFrameInfo::CIESP 116 DWARFCallFrameInfo::ParseCIE (const dw_offset_t cie_offset) 117 { 118 CIESP cie_sp(new CIE(cie_offset)); 119 dw_offset_t offset = cie_offset; 120 if (m_cfi_data_initialized == false) 121 { 122 m_section->ReadSectionDataFromObjectFile (&m_objfile, m_cfi_data); 123 m_cfi_data_initialized = true; 124 } 125 const uint32_t length = m_cfi_data.GetU32(&offset); 126 const dw_offset_t cie_id = m_cfi_data.GetU32(&offset); 127 const dw_offset_t end_offset = cie_offset + length + 4; 128 if (length > 0 && ((!m_is_eh_frame && cie_id == 0xfffffffful) || (m_is_eh_frame && cie_id == 0ul))) 129 { 130 size_t i; 131 // cie.offset = cie_offset; 132 // cie.length = length; 133 // cie.cieID = cieID; 134 cie_sp->ptr_encoding = DW_EH_PE_absptr; 135 cie_sp->version = m_cfi_data.GetU8(&offset); 136 137 for (i=0; i<CFI_AUG_MAX_SIZE; ++i) 138 { 139 cie_sp->augmentation[i] = m_cfi_data.GetU8(&offset); 140 if (cie_sp->augmentation[i] == '\0') 141 { 142 // Zero out remaining bytes in augmentation string 143 for (size_t j = i+1; j<CFI_AUG_MAX_SIZE; ++j) 144 cie_sp->augmentation[j] = '\0'; 145 146 break; 147 } 148 } 149 150 if (i == CFI_AUG_MAX_SIZE && cie_sp->augmentation[CFI_AUG_MAX_SIZE-1] != '\0') 151 { 152 fprintf(stderr, "CIE parse error: CIE augmentation string was too large for the fixed sized buffer of %d bytes.\n", CFI_AUG_MAX_SIZE); 153 return cie_sp; 154 } 155 cie_sp->code_align = (uint32_t)m_cfi_data.GetULEB128(&offset); 156 cie_sp->data_align = (int32_t)m_cfi_data.GetSLEB128(&offset); 157 cie_sp->return_addr_reg_num = m_cfi_data.GetU8(&offset); 158 159 if (cie_sp->augmentation[0]) 160 { 161 // Get the length of the eh_frame augmentation data 162 // which starts with a ULEB128 length in bytes 163 const size_t aug_data_len = (size_t)m_cfi_data.GetULEB128(&offset); 164 const size_t aug_data_end = offset + aug_data_len; 165 const size_t aug_str_len = strlen(cie_sp->augmentation); 166 // A 'z' may be present as the first character of the string. 167 // If present, the Augmentation Data field shall be present. 168 // The contents of the Augmentation Data shall be intepreted 169 // according to other characters in the Augmentation String. 170 if (cie_sp->augmentation[0] == 'z') 171 { 172 // Extract the Augmentation Data 173 size_t aug_str_idx = 0; 174 for (aug_str_idx = 1; aug_str_idx < aug_str_len; aug_str_idx++) 175 { 176 char aug = cie_sp->augmentation[aug_str_idx]; 177 switch (aug) 178 { 179 case 'L': 180 // Indicates the presence of one argument in the 181 // Augmentation Data of the CIE, and a corresponding 182 // argument in the Augmentation Data of the FDE. The 183 // argument in the Augmentation Data of the CIE is 184 // 1-byte and represents the pointer encoding used 185 // for the argument in the Augmentation Data of the 186 // FDE, which is the address of a language-specific 187 // data area (LSDA). The size of the LSDA pointer is 188 // specified by the pointer encoding used. 189 m_cfi_data.GetU8(&offset); 190 break; 191 192 case 'P': 193 // Indicates the presence of two arguments in the 194 // Augmentation Data of the cie_sp-> The first argument 195 // is 1-byte and represents the pointer encoding 196 // used for the second argument, which is the 197 // address of a personality routine handler. The 198 // size of the personality routine pointer is 199 // specified by the pointer encoding used. 200 { 201 uint8_t arg_ptr_encoding = m_cfi_data.GetU8(&offset); 202 m_cfi_data.GetGNUEHPointer(&offset, arg_ptr_encoding, LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS); 203 } 204 break; 205 206 case 'R': 207 // A 'R' may be present at any position after the 208 // first character of the string. The Augmentation 209 // Data shall include a 1 byte argument that 210 // represents the pointer encoding for the address 211 // pointers used in the FDE. 212 cie_sp->ptr_encoding = m_cfi_data.GetU8(&offset); 213 break; 214 } 215 } 216 } 217 else if (strcmp(cie_sp->augmentation, "eh") == 0) 218 { 219 // If the Augmentation string has the value "eh", then 220 // the EH Data field shall be present 221 } 222 223 // Set the offset to be the end of the augmentation data just in case 224 // we didn't understand any of the data. 225 offset = (uint32_t)aug_data_end; 226 } 227 228 if (end_offset > offset) 229 { 230 cie_sp->inst_offset = offset; 231 cie_sp->inst_length = end_offset - offset; 232 } 233 while (offset < end_offset) 234 { 235 uint8_t inst = m_cfi_data.GetU8(&offset); 236 uint8_t primary_opcode = inst & 0xC0; 237 uint8_t extended_opcode = inst & 0x3F; 238 239 if (extended_opcode == DW_CFA_def_cfa) 240 { 241 // Takes two unsigned LEB128 operands representing a register 242 // number and a (non-factored) offset. The required action 243 // is to define the current CFA rule to use the provided 244 // register and offset. 245 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 246 int op_offset = (int32_t)m_cfi_data.GetULEB128(&offset); 247 cie_sp->initial_row.SetCFARegister (reg_num); 248 cie_sp->initial_row.SetCFAOffset (op_offset); 249 continue; 250 } 251 if (primary_opcode == DW_CFA_offset) 252 { 253 // 0x80 - high 2 bits are 0x2, lower 6 bits are register. 254 // Takes two arguments: an unsigned LEB128 constant representing a 255 // factored offset and a register number. The required action is to 256 // change the rule for the register indicated by the register number 257 // to be an offset(N) rule with a value of 258 // (N = factored offset * data_align). 259 uint32_t reg_num = extended_opcode; 260 int op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * cie_sp->data_align; 261 UnwindPlan::Row::RegisterLocation reg_location; 262 reg_location.SetAtCFAPlusOffset(op_offset); 263 cie_sp->initial_row.SetRegisterInfo (reg_num, reg_location); 264 continue; 265 } 266 if (extended_opcode == DW_CFA_nop) 267 { 268 continue; 269 } 270 break; // Stop if we hit an unrecognized opcode 271 } 272 } 273 274 return cie_sp; 275 } 276 277 // Scan through the eh_frame or debug_frame section looking for FDEs and noting the start/end addresses 278 // of the functions and a pointer back to the function's FDE for later expansion. 279 // Internalize CIEs as we come across them. 280 281 void 282 DWARFCallFrameInfo::GetFDEIndex () 283 { 284 if (m_section.get() == NULL || m_section->IsEncrypted()) 285 return; 286 if (m_fde_index_initialized) 287 return; 288 289 290 dw_offset_t offset = 0; 291 if (m_cfi_data_initialized == false) 292 { 293 LogSP log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND)); 294 if (log) 295 { 296 log->Printf ("Reading eh_frame information for %s", m_objfile.GetFileSpec().GetFilename().GetCString()); 297 } 298 m_section->ReadSectionDataFromObjectFile (&m_objfile, m_cfi_data); 299 m_cfi_data_initialized = true; 300 } 301 while (m_cfi_data.ValidOffsetForDataOfSize (offset, 8)) 302 { 303 dw_offset_t current_entry = offset; 304 uint32_t len = m_cfi_data.GetU32 (&offset); 305 dw_offset_t next_entry = current_entry + len + 4; 306 dw_offset_t cie_id = m_cfi_data.GetU32 (&offset); 307 308 if (cie_id == 0 || cie_id == UINT32_MAX) 309 { 310 m_cie_map[current_entry] = ParseCIE (current_entry); 311 offset = next_entry; 312 continue; 313 } 314 315 const CIE *cie = GetCIE (current_entry + 4 - cie_id); 316 assert (cie != NULL); 317 318 const lldb::addr_t pc_rel_addr = m_section->GetFileAddress(); 319 const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS; 320 const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS; 321 322 lldb::addr_t addr = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding, pc_rel_addr, text_addr, data_addr); 323 lldb::addr_t length = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding & DW_EH_PE_MASK_ENCODING, pc_rel_addr, text_addr, data_addr); 324 FDEEntry fde; 325 fde.bounds = AddressRange (addr, length, m_objfile.GetSectionList()); 326 fde.offset = current_entry; 327 m_fde_index.push_back(fde); 328 329 offset = next_entry; 330 } 331 std::sort (m_fde_index.begin(), m_fde_index.end()); 332 m_fde_index_initialized = true; 333 } 334 335 bool 336 DWARFCallFrameInfo::FDEToUnwindPlan (dw_offset_t offset, Address startaddr, UnwindPlan& unwind_plan) 337 { 338 dw_offset_t current_entry = offset; 339 340 if (m_section.get() == NULL || m_section->IsEncrypted()) 341 return false; 342 343 if (m_cfi_data_initialized == false) 344 { 345 m_section->ReadSectionDataFromObjectFile (&m_objfile, m_cfi_data); 346 m_cfi_data_initialized = true; 347 } 348 349 uint32_t length = m_cfi_data.GetU32 (&offset); 350 dw_offset_t cie_offset = m_cfi_data.GetU32 (&offset); 351 352 assert (cie_offset != 0 && cie_offset != UINT32_MAX); 353 354 // Translate the CIE_id from the eh_frame format, which 355 // is relative to the FDE offset, into a __eh_frame section 356 // offset 357 if (m_is_eh_frame) 358 { 359 unwind_plan.SetSourceName ("eh_frame CFI"); 360 cie_offset = current_entry + 4 - cie_offset; 361 } 362 else 363 { 364 unwind_plan.SetSourceName ("DWARF CFI"); 365 } 366 367 const CIE *cie = GetCIE (cie_offset); 368 assert (cie != NULL); 369 370 const dw_offset_t end_offset = current_entry + length + 4; 371 372 const lldb::addr_t pc_rel_addr = m_section->GetFileAddress(); 373 const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS; 374 const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS; 375 lldb::addr_t range_base = m_cfi_data.GetGNUEHPointer(&offset, cie->ptr_encoding, pc_rel_addr, text_addr, data_addr); 376 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); 377 AddressRange range (range_base, m_objfile.GetAddressByteSize(), m_objfile.GetSectionList()); 378 range.SetByteSize (range_len); 379 380 if (cie->augmentation[0] == 'z') 381 { 382 uint32_t aug_data_len = (uint32_t)m_cfi_data.GetULEB128(&offset); 383 offset += aug_data_len; 384 } 385 386 uint32_t reg_num = 0; 387 int32_t op_offset = 0; 388 uint32_t tmp_uval32; 389 uint32_t code_align = cie->code_align; 390 int32_t data_align = cie->data_align; 391 392 unwind_plan.SetPlanValidAddressRange (range); 393 UnwindPlan::Row row = cie->initial_row; 394 395 unwind_plan.SetRegisterKind (m_reg_kind); 396 397 UnwindPlan::Row::RegisterLocation reg_location; 398 while (m_cfi_data.ValidOffset(offset) && offset < end_offset) 399 { 400 uint8_t inst = m_cfi_data.GetU8(&offset); 401 uint8_t primary_opcode = inst & 0xC0; 402 uint8_t extended_opcode = inst & 0x3F; 403 404 if (primary_opcode) 405 { 406 switch (primary_opcode) 407 { 408 case DW_CFA_advance_loc : // (Row Creation Instruction) 409 { // 0x40 - high 2 bits are 0x1, lower 6 bits are delta 410 // takes a single argument that represents a constant delta. The 411 // required action is to create a new table row with a location 412 // value that is computed by taking the current entry's location 413 // value and adding (delta * code_align). All other 414 // values in the new row are initially identical to the current row. 415 unwind_plan.AppendRow(row); 416 row.SlideOffset(extended_opcode * code_align); 417 } 418 break; 419 420 case DW_CFA_offset : 421 { // 0x80 - high 2 bits are 0x2, lower 6 bits are register 422 // takes two arguments: an unsigned LEB128 constant representing a 423 // factored offset and a register number. The required action is to 424 // change the rule for the register indicated by the register number 425 // to be an offset(N) rule with a value of 426 // (N = factored offset * data_align). 427 reg_num = extended_opcode; 428 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align; 429 reg_location.SetAtCFAPlusOffset(op_offset); 430 row.SetRegisterInfo (reg_num, reg_location); 431 } 432 break; 433 434 case DW_CFA_restore : 435 { // 0xC0 - high 2 bits are 0x3, lower 6 bits are register 436 // takes a single argument that represents a register number. The 437 // required action is to change the rule for the indicated register 438 // to the rule assigned it by the initial_instructions in the CIE. 439 reg_num = extended_opcode; 440 // We only keep enough register locations around to 441 // unwind what is in our thread, and these are organized 442 // by the register index in that state, so we need to convert our 443 // GCC register number from the EH frame info, to a register index 444 445 if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0).GetRegisterInfo(reg_num, reg_location)) 446 row.SetRegisterInfo (reg_num, reg_location); 447 } 448 break; 449 } 450 } 451 else 452 { 453 switch (extended_opcode) 454 { 455 case DW_CFA_nop : // 0x0 456 break; 457 458 case DW_CFA_set_loc : // 0x1 (Row Creation Instruction) 459 { 460 // DW_CFA_set_loc takes a single argument that represents an address. 461 // The required action is to create a new table row using the 462 // specified address as the location. All other values in the new row 463 // are initially identical to the current row. The new location value 464 // should always be greater than the current one. 465 unwind_plan.AppendRow(row); 466 row.SetOffset(m_cfi_data.GetPointer(&offset) - startaddr.GetFileAddress()); 467 } 468 break; 469 470 case DW_CFA_advance_loc1 : // 0x2 (Row Creation Instruction) 471 { 472 // takes a single uword argument that represents a constant delta. 473 // This instruction is identical to DW_CFA_advance_loc except for the 474 // encoding and size of the delta argument. 475 unwind_plan.AppendRow(row); 476 row.SlideOffset (m_cfi_data.GetU8(&offset) * code_align); 477 } 478 break; 479 480 case DW_CFA_advance_loc2 : // 0x3 (Row Creation Instruction) 481 { 482 // takes a single uword argument that represents a constant delta. 483 // This instruction is identical to DW_CFA_advance_loc except for the 484 // encoding and size of the delta argument. 485 unwind_plan.AppendRow(row); 486 row.SlideOffset (m_cfi_data.GetU16(&offset) * code_align); 487 } 488 break; 489 490 case DW_CFA_advance_loc4 : // 0x4 (Row Creation Instruction) 491 { 492 // takes a single uword argument that represents a constant delta. 493 // This instruction is identical to DW_CFA_advance_loc except for the 494 // encoding and size of the delta argument. 495 unwind_plan.AppendRow(row); 496 row.SlideOffset (m_cfi_data.GetU32(&offset) * code_align); 497 } 498 break; 499 500 case DW_CFA_offset_extended : // 0x5 501 { 502 // takes two unsigned LEB128 arguments representing a register number 503 // and a factored offset. This instruction is identical to DW_CFA_offset 504 // except for the encoding and size of the register argument. 505 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 506 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset) * data_align; 507 reg_location.SetAtCFAPlusOffset(op_offset); 508 row.SetRegisterInfo (reg_num, reg_location); 509 } 510 break; 511 512 case DW_CFA_restore_extended : // 0x6 513 { 514 // takes a single unsigned LEB128 argument that represents a register 515 // number. This instruction is identical to DW_CFA_restore except for 516 // the encoding and size of the register argument. 517 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 518 if (unwind_plan.IsValidRowIndex(0) && unwind_plan.GetRowAtIndex(0).GetRegisterInfo(reg_num, reg_location)) 519 row.SetRegisterInfo (reg_num, reg_location); 520 } 521 break; 522 523 case DW_CFA_undefined : // 0x7 524 { 525 // takes a single unsigned LEB128 argument that represents a register 526 // number. The required action is to set the rule for the specified 527 // register to undefined. 528 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 529 reg_location.SetUndefined(); 530 row.SetRegisterInfo (reg_num, reg_location); 531 } 532 break; 533 534 case DW_CFA_same_value : // 0x8 535 { 536 // takes a single unsigned LEB128 argument that represents a register 537 // number. The required action is to set the rule for the specified 538 // register to same value. 539 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 540 reg_location.SetSame(); 541 row.SetRegisterInfo (reg_num, reg_location); 542 } 543 break; 544 545 case DW_CFA_register : // 0x9 546 { 547 // takes two unsigned LEB128 arguments representing register numbers. 548 // The required action is to set the rule for the first register to be 549 // the second register. 550 551 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 552 uint32_t other_reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 553 reg_location.SetInRegister(other_reg_num); 554 row.SetRegisterInfo (reg_num, reg_location); 555 } 556 break; 557 558 case DW_CFA_remember_state : // 0xA 559 // These instructions define a stack of information. Encountering the 560 // DW_CFA_remember_state instruction means to save the rules for every 561 // register on the current row on the stack. Encountering the 562 // DW_CFA_restore_state instruction means to pop the set of rules off 563 // the stack and place them in the current row. (This operation is 564 // useful for compilers that move epilogue code into the body of a 565 // function.) 566 unwind_plan.AppendRow (row); 567 break; 568 569 case DW_CFA_restore_state : // 0xB 570 // These instructions define a stack of information. Encountering the 571 // DW_CFA_remember_state instruction means to save the rules for every 572 // register on the current row on the stack. Encountering the 573 // DW_CFA_restore_state instruction means to pop the set of rules off 574 // the stack and place them in the current row. (This operation is 575 // useful for compilers that move epilogue code into the body of a 576 // function.) 577 { 578 row = unwind_plan.GetRowAtIndex(unwind_plan.GetRowCount() - 1); 579 } 580 break; 581 582 case DW_CFA_def_cfa : // 0xC (CFA Definition Instruction) 583 { 584 // Takes two unsigned LEB128 operands representing a register 585 // number and a (non-factored) offset. The required action 586 // is to define the current CFA rule to use the provided 587 // register and offset. 588 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 589 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset); 590 row.SetCFARegister (reg_num); 591 row.SetCFAOffset (op_offset); 592 } 593 break; 594 595 case DW_CFA_def_cfa_register : // 0xD (CFA Definition Instruction) 596 { 597 // takes a single unsigned LEB128 argument representing a register 598 // number. The required action is to define the current CFA rule to 599 // use the provided register (but to keep the old offset). 600 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 601 row.SetCFARegister (reg_num); 602 } 603 break; 604 605 case DW_CFA_def_cfa_offset : // 0xE (CFA Definition Instruction) 606 { 607 // Takes a single unsigned LEB128 operand representing a 608 // (non-factored) offset. The required action is to define 609 // the current CFA rule to use the provided offset (but 610 // to keep the old register). 611 op_offset = (int32_t)m_cfi_data.GetULEB128(&offset); 612 row.SetCFAOffset (op_offset); 613 } 614 break; 615 616 case DW_CFA_def_cfa_expression : // 0xF (CFA Definition Instruction) 617 { 618 size_t block_len = (size_t)m_cfi_data.GetULEB128(&offset); 619 offset += (uint32_t)block_len; 620 } 621 break; 622 623 case DW_CFA_expression : // 0x10 624 { 625 // Takes two operands: an unsigned LEB128 value representing 626 // a register number, and a DW_FORM_block value representing a DWARF 627 // expression. The required action is to change the rule for the 628 // register indicated by the register number to be an expression(E) 629 // rule where E is the DWARF expression. That is, the DWARF 630 // expression computes the address. The value of the CFA is 631 // pushed on the DWARF evaluation stack prior to execution of 632 // the DWARF expression. 633 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 634 uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset); 635 const uint8_t *block_data = (uint8_t *)m_cfi_data.GetData(&offset, block_len); 636 637 reg_location.SetAtDWARFExpression(block_data, block_len); 638 row.SetRegisterInfo (reg_num, reg_location); 639 } 640 break; 641 642 case DW_CFA_offset_extended_sf : // 0x11 643 { 644 // takes two operands: an unsigned LEB128 value representing a 645 // register number and a signed LEB128 factored offset. This 646 // instruction is identical to DW_CFA_offset_extended except 647 //that the second operand is signed and factored. 648 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 649 op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align; 650 reg_location.SetAtCFAPlusOffset(op_offset); 651 row.SetRegisterInfo (reg_num, reg_location); 652 } 653 break; 654 655 case DW_CFA_def_cfa_sf : // 0x12 (CFA Definition Instruction) 656 { 657 // Takes two operands: an unsigned LEB128 value representing 658 // a register number and a signed LEB128 factored offset. 659 // This instruction is identical to DW_CFA_def_cfa except 660 // that the second operand is signed and factored. 661 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 662 op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align; 663 row.SetCFARegister (reg_num); 664 row.SetCFAOffset (op_offset); 665 } 666 break; 667 668 case DW_CFA_def_cfa_offset_sf : // 0x13 (CFA Definition Instruction) 669 { 670 // takes a signed LEB128 operand representing a factored 671 // offset. This instruction is identical to DW_CFA_def_cfa_offset 672 // except that the operand is signed and factored. 673 op_offset = (int32_t)m_cfi_data.GetSLEB128(&offset) * data_align; 674 row.SetCFAOffset (op_offset); 675 } 676 break; 677 678 case DW_CFA_val_expression : // 0x16 679 { 680 // takes two operands: an unsigned LEB128 value representing a register 681 // number, and a DW_FORM_block value representing a DWARF expression. 682 // The required action is to change the rule for the register indicated 683 // by the register number to be a val_expression(E) rule where E is the 684 // DWARF expression. That is, the DWARF expression computes the value of 685 // the given register. The value of the CFA is pushed on the DWARF 686 // evaluation stack prior to execution of the DWARF expression. 687 reg_num = (uint32_t)m_cfi_data.GetULEB128(&offset); 688 uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(&offset); 689 const uint8_t* block_data = (uint8_t*)m_cfi_data.GetData(&offset, block_len); 690 //#if defined(__i386__) || defined(__x86_64__) 691 // // The EH frame info for EIP and RIP contains code that looks for traps to 692 // // be a specific type and increments the PC. 693 // // For i386: 694 // // DW_CFA_val_expression where: 695 // // eip = DW_OP_breg6(+28), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x34), 696 // // DW_OP_deref, DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref, 697 // // DW_OP_dup, DW_OP_lit3, DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne, 698 // // DW_OP_and, DW_OP_plus 699 // // This basically does a: 700 // // eip = ucontenxt.mcontext32->gpr.eip; 701 // // if (ucontenxt.mcontext32->exc.trapno != 3 && ucontenxt.mcontext32->exc.trapno != 4) 702 // // eip++; 703 // // 704 // // For x86_64: 705 // // DW_CFA_val_expression where: 706 // // rip = DW_OP_breg3(+48), DW_OP_deref, DW_OP_dup, DW_OP_plus_uconst(0x90), DW_OP_deref, 707 // // DW_OP_swap, DW_OP_plus_uconst(0), DW_OP_deref_size(4), DW_OP_dup, DW_OP_lit3, 708 // // DW_OP_ne, DW_OP_swap, DW_OP_lit4, DW_OP_ne, DW_OP_and, DW_OP_plus 709 // // This basically does a: 710 // // rip = ucontenxt.mcontext64->gpr.rip; 711 // // if (ucontenxt.mcontext64->exc.trapno != 3 && ucontenxt.mcontext64->exc.trapno != 4) 712 // // rip++; 713 // // The trap comparisons and increments are not needed as it hoses up the unwound PC which 714 // // is expected to point at least past the instruction that causes the fault/trap. So we 715 // // take it out by trimming the expression right at the first "DW_OP_swap" opcodes 716 // if (block_data != NULL && thread->GetPCRegNum(Thread::GCC) == reg_num) 717 // { 718 // if (thread->Is64Bit()) 719 // { 720 // if (block_len > 9 && block_data[8] == DW_OP_swap && block_data[9] == DW_OP_plus_uconst) 721 // block_len = 8; 722 // } 723 // else 724 // { 725 // if (block_len > 8 && block_data[7] == DW_OP_swap && block_data[8] == DW_OP_plus_uconst) 726 // block_len = 7; 727 // } 728 // } 729 //#endif 730 reg_location.SetIsDWARFExpression(block_data, block_len); 731 row.SetRegisterInfo (reg_num, reg_location); 732 } 733 break; 734 735 case DW_CFA_val_offset : // 0x14 736 case DW_CFA_val_offset_sf : // 0x15 737 default: 738 tmp_uval32 = extended_opcode; 739 break; 740 } 741 } 742 } 743 unwind_plan.AppendRow(row); 744 745 return true; 746 } 747