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
DWARFCallFrameInfo(ObjectFile & objfile,SectionSP & section_sp,lldb::RegisterKind reg_kind,bool is_eh_frame)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
~DWARFCallFrameInfo()45 DWARFCallFrameInfo::~DWARFCallFrameInfo()
46 {
47 }
48
49
50 bool
GetUnwindPlan(Address addr,UnwindPlan & unwind_plan)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
GetAddressRange(Address addr,AddressRange & range)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
GetFDEEntryByFileAddress(addr_t file_addr,FDEEntryMap::Entry & fde_entry)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
GetFunctionAddressAndSizeVector(FunctionAddressAndSizeVector & function_info)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*
GetCIE(dw_offset_t cie_offset)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
ParseCIE(const dw_offset_t cie_offset)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
GetCFIData()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
GetFDEIndex()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
FDEToUnwindPlan(dw_offset_t dwarf_offset,Address startaddr,UnwindPlan & unwind_plan)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