1//===-- DWARFCallFrameInfo.cpp --------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "lldb/Symbol/DWARFCallFrameInfo.h"
10#include "lldb/Core/Debugger.h"
11#include "lldb/Core/Module.h"
12#include "lldb/Core/Section.h"
13#include "lldb/Core/dwarf.h"
14#include "lldb/Host/Host.h"
15#include "lldb/Symbol/ObjectFile.h"
16#include "lldb/Symbol/UnwindPlan.h"
17#include "lldb/Target/RegisterContext.h"
18#include "lldb/Target/Thread.h"
19#include "lldb/Utility/ArchSpec.h"
20#include "lldb/Utility/LLDBLog.h"
21#include "lldb/Utility/Log.h"
22#include "lldb/Utility/Timer.h"
23#include <cstring>
24#include <list>
25#include <optional>
26
27using namespace lldb;
28using namespace lldb_private;
29using namespace lldb_private::dwarf;
30
31// GetDwarfEHPtr
32//
33// Used for calls when the value type is specified by a DWARF EH Frame pointer
34// encoding.
35static uint64_t
36GetGNUEHPointer(const DataExtractor &DE, lldb::offset_t *offset_ptr,
37 uint32_t eh_ptr_enc, addr_t pc_rel_addr, addr_t text_addr,
38 addr_t data_addr) //, BSDRelocs *data_relocs) const
39{
40 if (eh_ptr_enc == DW_EH_PE_omit)
41 return ULLONG_MAX; // Value isn't in the buffer...
42
43 uint64_t baseAddress = 0;
44 uint64_t addressValue = 0;
45 const uint32_t addr_size = DE.GetAddressByteSize();
46 assert(addr_size == 4 || addr_size == 8);
47
48 bool signExtendValue = false;
49 // Decode the base part or adjust our offset
50 switch (eh_ptr_enc & 0x70) {
51 case DW_EH_PE_pcrel:
52 signExtendValue = true;
53 baseAddress = *offset_ptr;
54 if (pc_rel_addr != LLDB_INVALID_ADDRESS)
55 baseAddress += pc_rel_addr;
56 // else
57 // Log::GlobalWarning ("PC relative pointer encoding found with
58 // invalid pc relative address.");
59 break;
60
61 case DW_EH_PE_textrel:
62 signExtendValue = true;
63 if (text_addr != LLDB_INVALID_ADDRESS)
64 baseAddress = text_addr;
65 // else
66 // Log::GlobalWarning ("text relative pointer encoding being
67 // decoded with invalid text section address, setting base address
68 // to zero.");
69 break;
70
71 case DW_EH_PE_datarel:
72 signExtendValue = true;
73 if (data_addr != LLDB_INVALID_ADDRESS)
74 baseAddress = data_addr;
75 // else
76 // Log::GlobalWarning ("data relative pointer encoding being
77 // decoded with invalid data section address, setting base address
78 // to zero.");
79 break;
80
81 case DW_EH_PE_funcrel:
82 signExtendValue = true;
83 break;
84
85 case DW_EH_PE_aligned: {
86 // SetPointerSize should be called prior to extracting these so the pointer
87 // size is cached
88 assert(addr_size != 0);
89 if (addr_size) {
90 // Align to a address size boundary first
91 uint32_t alignOffset = *offset_ptr % addr_size;
92 if (alignOffset)
93 offset_ptr += addr_size - alignOffset;
94 }
95 } break;
96
97 default:
98 break;
99 }
100
101 // Decode the value part
102 switch (eh_ptr_enc & DW_EH_PE_MASK_ENCODING) {
103 case DW_EH_PE_absptr: {
104 addressValue = DE.GetAddress(offset_ptr);
105 // if (data_relocs)
106 // addressValue = data_relocs->Relocate(*offset_ptr -
107 // addr_size, *this, addressValue);
108 } break;
109 case DW_EH_PE_uleb128:
110 addressValue = DE.GetULEB128(offset_ptr);
111 break;
112 case DW_EH_PE_udata2:
113 addressValue = DE.GetU16(offset_ptr);
114 break;
115 case DW_EH_PE_udata4:
116 addressValue = DE.GetU32(offset_ptr);
117 break;
118 case DW_EH_PE_udata8:
119 addressValue = DE.GetU64(offset_ptr);
120 break;
121 case DW_EH_PE_sleb128:
122 addressValue = DE.GetSLEB128(offset_ptr);
123 break;
124 case DW_EH_PE_sdata2:
125 addressValue = (int16_t)DE.GetU16(offset_ptr);
126 break;
127 case DW_EH_PE_sdata4:
128 addressValue = (int32_t)DE.GetU32(offset_ptr);
129 break;
130 case DW_EH_PE_sdata8:
131 addressValue = (int64_t)DE.GetU64(offset_ptr);
132 break;
133 default:
134 // Unhandled encoding type
135 assert(eh_ptr_enc);
136 break;
137 }
138
139 // Since we promote everything to 64 bit, we may need to sign extend
140 if (signExtendValue && addr_size < sizeof(baseAddress)) {
141 uint64_t sign_bit = 1ull << ((addr_size * 8ull) - 1ull);
142 if (sign_bit & addressValue) {
143 uint64_t mask = ~sign_bit + 1;
144 addressValue |= mask;
145 }
146 }
147 return baseAddress + addressValue;
148}
149
150DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile &objfile,
151 SectionSP &section_sp, Type type)
152 : m_objfile(objfile), m_section_sp(section_sp), m_type(type) {}
153
154std::unique_ptr<UnwindPlan>
155DWARFCallFrameInfo::GetUnwindPlan(const Address &addr) {
156 return GetUnwindPlan(ranges: {AddressRange(addr, 1)}, addr);
157}
158
159std::unique_ptr<UnwindPlan>
160DWARFCallFrameInfo::GetUnwindPlan(llvm::ArrayRef<AddressRange> ranges,
161 const Address &addr) {
162 FDEEntryMap::Entry fde_entry;
163
164 // Make sure that the Address we're searching for is the same object file as
165 // this DWARFCallFrameInfo, we only store File offsets in m_fde_index.
166 ModuleSP module_sp = addr.GetModule();
167 if (module_sp.get() == nullptr || module_sp->GetObjectFile() == nullptr ||
168 module_sp->GetObjectFile() != &m_objfile)
169 return nullptr;
170
171 std::vector<AddressRange> valid_ranges;
172
173 auto result = std::make_unique<UnwindPlan>(args: GetRegisterKind());
174 result->SetSourceName(m_type == EH ? "eh_frame CFI" : "DWARF CFI");
175 // In theory the debug_frame info should be valid at all call sites
176 // ("asynchronous unwind info" as it is sometimes called) but in practice
177 // gcc et al all emit call frame info for the prologue and call sites, but
178 // not for the epilogue or all the other locations during the function
179 // reliably.
180 result->SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
181 result->SetSourcedFromCompiler(eLazyBoolYes);
182 result->SetUnwindPlanForSignalTrap(eLazyBoolNo);
183 for (const AddressRange &range : ranges) {
184 std::optional<FDEEntryMap::Entry> entry = GetFirstFDEEntryInRange(range);
185 if (!entry)
186 continue;
187 std::optional<FDE> fde = ParseFDE(offset: entry->data, startaddr: addr);
188 if (!fde)
189 continue;
190 int64_t slide =
191 fde->range.GetBaseAddress().GetFileAddress() - addr.GetFileAddress();
192 valid_ranges.push_back(x: std::move(fde->range));
193 if (fde->for_signal_trap)
194 result->SetUnwindPlanForSignalTrap(eLazyBoolYes);
195 result->SetReturnAddressRegister(fde->return_addr_reg_num);
196 for (UnwindPlan::Row &row : fde->rows) {
197 row.SlideOffset(offset: slide);
198 result->AppendRow(row: std::move(row));
199 }
200 }
201 result->SetPlanValidAddressRanges(std::move(valid_ranges));
202 if (result->GetRowCount() == 0)
203 return nullptr;
204 return result;
205}
206
207bool DWARFCallFrameInfo::GetAddressRange(Address addr, AddressRange &range) {
208
209 // Make sure that the Address we're searching for is the same object file as
210 // this DWARFCallFrameInfo, we only store File offsets in m_fde_index.
211 ModuleSP module_sp = addr.GetModule();
212 if (module_sp.get() == nullptr || module_sp->GetObjectFile() == nullptr ||
213 module_sp->GetObjectFile() != &m_objfile)
214 return false;
215
216 if (m_section_sp.get() == nullptr || m_section_sp->IsEncrypted())
217 return false;
218 GetFDEIndex();
219 FDEEntryMap::Entry *fde_entry =
220 m_fde_index.FindEntryThatContains(addr: addr.GetFileAddress());
221 if (!fde_entry)
222 return false;
223
224 range = AddressRange(fde_entry->base, fde_entry->size,
225 m_objfile.GetSectionList());
226 return true;
227}
228
229std::optional<DWARFCallFrameInfo::FDEEntryMap::Entry>
230DWARFCallFrameInfo::GetFirstFDEEntryInRange(const AddressRange &range) {
231 if (!m_section_sp || m_section_sp->IsEncrypted())
232 return std::nullopt;
233
234 GetFDEIndex();
235
236 addr_t start_file_addr = range.GetBaseAddress().GetFileAddress();
237 const FDEEntryMap::Entry *fde =
238 m_fde_index.FindEntryThatContainsOrFollows(addr: start_file_addr);
239 if (fde && fde->DoesIntersect(
240 rhs: FDEEntryMap::Range(start_file_addr, range.GetByteSize())))
241 return *fde;
242
243 return std::nullopt;
244}
245
246void DWARFCallFrameInfo::GetFunctionAddressAndSizeVector(
247 FunctionAddressAndSizeVector &function_info) {
248 GetFDEIndex();
249 const size_t count = m_fde_index.GetSize();
250 function_info.Clear();
251 if (count > 0)
252 function_info.Reserve(size: count);
253 for (size_t i = 0; i < count; ++i) {
254 const FDEEntryMap::Entry *func_offset_data_entry =
255 m_fde_index.GetEntryAtIndex(i);
256 if (func_offset_data_entry) {
257 FunctionAddressAndSizeVector::Entry function_offset_entry(
258 func_offset_data_entry->base, func_offset_data_entry->size);
259 function_info.Append(entry: function_offset_entry);
260 }
261 }
262}
263
264const DWARFCallFrameInfo::CIE *
265DWARFCallFrameInfo::GetCIE(dw_offset_t cie_offset) {
266 cie_map_t::iterator pos = m_cie_map.find(x: cie_offset);
267
268 if (pos != m_cie_map.end()) {
269 // Parse and cache the CIE
270 if (pos->second == nullptr)
271 pos->second = ParseCIE(cie_offset);
272
273 return pos->second.get();
274 }
275 return nullptr;
276}
277
278DWARFCallFrameInfo::CIESP
279DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
280 CIESP cie_sp(new CIE(cie_offset));
281 lldb::offset_t offset = cie_offset;
282 if (!m_cfi_data_initialized)
283 GetCFIData();
284 uint32_t length = m_cfi_data.GetU32(offset_ptr: &offset);
285 dw_offset_t cie_id, end_offset;
286 bool is_64bit = (length == UINT32_MAX);
287 if (is_64bit) {
288 length = m_cfi_data.GetU64(offset_ptr: &offset);
289 cie_id = m_cfi_data.GetU64(offset_ptr: &offset);
290 end_offset = cie_offset + length + 12;
291 } else {
292 cie_id = m_cfi_data.GetU32(offset_ptr: &offset);
293 end_offset = cie_offset + length + 4;
294 }
295 if (length > 0 && ((m_type == DWARF && cie_id == UINT32_MAX) ||
296 (m_type == EH && cie_id == 0ul))) {
297 size_t i;
298 // cie.offset = cie_offset;
299 // cie.length = length;
300 // cie.cieID = cieID;
301 cie_sp->ptr_encoding = DW_EH_PE_absptr; // default
302 cie_sp->version = m_cfi_data.GetU8(offset_ptr: &offset);
303 if (cie_sp->version > CFI_VERSION4) {
304 Debugger::ReportError(
305 message: llvm::formatv(Fmt: "CIE parse error: CFI version {0} is not supported",
306 Vals&: cie_sp->version));
307 return nullptr;
308 }
309
310 for (i = 0; i < CFI_AUG_MAX_SIZE; ++i) {
311 cie_sp->augmentation[i] = m_cfi_data.GetU8(offset_ptr: &offset);
312 if (cie_sp->augmentation[i] == '\0') {
313 // Zero out remaining bytes in augmentation string
314 for (size_t j = i + 1; j < CFI_AUG_MAX_SIZE; ++j)
315 cie_sp->augmentation[j] = '\0';
316
317 break;
318 }
319 }
320
321 if (i == CFI_AUG_MAX_SIZE &&
322 cie_sp->augmentation[CFI_AUG_MAX_SIZE - 1] != '\0') {
323 Debugger::ReportError(message: llvm::formatv(
324 Fmt: "CIE parse error: CIE augmentation string was too large "
325 "for the fixed sized buffer of {0} bytes.",
326 Vals: CFI_AUG_MAX_SIZE));
327 return nullptr;
328 }
329
330 // m_cfi_data uses address size from target architecture of the process may
331 // ignore these fields?
332 if (m_type == DWARF && cie_sp->version >= CFI_VERSION4) {
333 cie_sp->address_size = m_cfi_data.GetU8(offset_ptr: &offset);
334 cie_sp->segment_size = m_cfi_data.GetU8(offset_ptr: &offset);
335 }
336
337 cie_sp->code_align = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
338 cie_sp->data_align = (int32_t)m_cfi_data.GetSLEB128(offset_ptr: &offset);
339
340 cie_sp->return_addr_reg_num =
341 m_type == DWARF && cie_sp->version >= CFI_VERSION3
342 ? static_cast<uint32_t>(m_cfi_data.GetULEB128(offset_ptr: &offset))
343 : m_cfi_data.GetU8(offset_ptr: &offset);
344
345 if (cie_sp->augmentation[0]) {
346 // Get the length of the eh_frame augmentation data which starts with a
347 // ULEB128 length in bytes
348 const size_t aug_data_len = (size_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
349 const size_t aug_data_end = offset + aug_data_len;
350 const size_t aug_str_len = strlen(s: cie_sp->augmentation);
351 // A 'z' may be present as the first character of the string.
352 // If present, the Augmentation Data field shall be present. The contents
353 // of the Augmentation Data shall be interpreted according to other
354 // characters in the Augmentation String.
355 if (cie_sp->augmentation[0] == 'z') {
356 // Extract the Augmentation Data
357 size_t aug_str_idx = 0;
358 for (aug_str_idx = 1; aug_str_idx < aug_str_len; aug_str_idx++) {
359 char aug = cie_sp->augmentation[aug_str_idx];
360 switch (aug) {
361 case 'L':
362 // Indicates the presence of one argument in the Augmentation Data
363 // of the CIE, and a corresponding argument in the Augmentation
364 // Data of the FDE. The argument in the Augmentation Data of the
365 // CIE is 1-byte and represents the pointer encoding used for the
366 // argument in the Augmentation Data of the FDE, which is the
367 // address of a language-specific data area (LSDA). The size of the
368 // LSDA pointer is specified by the pointer encoding used.
369 cie_sp->lsda_addr_encoding = m_cfi_data.GetU8(offset_ptr: &offset);
370 break;
371
372 case 'P':
373 // Indicates the presence of two arguments in the Augmentation Data
374 // of the CIE. The first argument is 1-byte and represents the
375 // pointer encoding used for the second argument, which is the
376 // address of a personality routine handler. The size of the
377 // personality routine pointer is specified by the pointer encoding
378 // used.
379 //
380 // The address of the personality function will be stored at this
381 // location. Pre-execution, it will be all zero's so don't read it
382 // until we're trying to do an unwind & the reloc has been
383 // resolved.
384 {
385 uint8_t arg_ptr_encoding = m_cfi_data.GetU8(offset_ptr: &offset);
386 const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
387 cie_sp->personality_loc = GetGNUEHPointer(
388 DE: m_cfi_data, offset_ptr: &offset, eh_ptr_enc: arg_ptr_encoding, pc_rel_addr,
389 LLDB_INVALID_ADDRESS, LLDB_INVALID_ADDRESS);
390 }
391 break;
392
393 case 'R':
394 // A 'R' may be present at any position after the
395 // first character of the string. The Augmentation Data shall
396 // include a 1 byte argument that represents the pointer encoding
397 // for the address pointers used in the FDE. Example: 0x1B ==
398 // DW_EH_PE_pcrel | DW_EH_PE_sdata4
399 cie_sp->ptr_encoding = m_cfi_data.GetU8(offset_ptr: &offset);
400 break;
401 }
402 }
403 } else if (strcmp(s1: cie_sp->augmentation, s2: "eh") == 0) {
404 // If the Augmentation string has the value "eh", then the EH Data
405 // field shall be present
406 }
407
408 // Set the offset to be the end of the augmentation data just in case we
409 // didn't understand any of the data.
410 offset = (uint32_t)aug_data_end;
411 }
412
413 if (end_offset > offset) {
414 cie_sp->inst_offset = offset;
415 cie_sp->inst_length = end_offset - offset;
416 }
417 while (offset < end_offset) {
418 uint8_t inst = m_cfi_data.GetU8(offset_ptr: &offset);
419 uint8_t primary_opcode = inst & 0xC0;
420 uint8_t extended_opcode = inst & 0x3F;
421
422 if (!HandleCommonDwarfOpcode(primary_opcode, extended_opcode,
423 data_align: cie_sp->data_align, offset,
424 row&: cie_sp->initial_row))
425 break; // Stop if we hit an unrecognized opcode
426 }
427 }
428
429 return cie_sp;
430}
431
432void DWARFCallFrameInfo::GetCFIData() {
433 if (!m_cfi_data_initialized) {
434 Log *log = GetLog(mask: LLDBLog::Unwind);
435 if (log)
436 m_objfile.GetModule()->LogMessage(log, format: "Reading EH frame info");
437 m_objfile.ReadSectionData(section: m_section_sp.get(), section_data&: m_cfi_data);
438 m_cfi_data_initialized = true;
439 }
440}
441// Scan through the eh_frame or debug_frame section looking for FDEs and noting
442// the start/end addresses of the functions and a pointer back to the
443// function's FDE for later expansion. Internalize CIEs as we come across them.
444
445void DWARFCallFrameInfo::GetFDEIndex() {
446 if (m_section_sp.get() == nullptr || m_section_sp->IsEncrypted())
447 return;
448
449 if (m_fde_index_initialized)
450 return;
451
452 std::lock_guard<std::mutex> guard(m_fde_index_mutex);
453
454 if (m_fde_index_initialized) // if two threads hit the locker
455 return;
456
457 LLDB_SCOPED_TIMERF("%s", m_objfile.GetFileSpec().GetFilename().AsCString(""));
458
459 bool clear_address_zeroth_bit = false;
460 if (ArchSpec arch = m_objfile.GetArchitecture()) {
461 if (arch.GetTriple().getArch() == llvm::Triple::arm ||
462 arch.GetTriple().getArch() == llvm::Triple::thumb)
463 clear_address_zeroth_bit = true;
464 }
465
466 lldb::offset_t offset = 0;
467 if (!m_cfi_data_initialized)
468 GetCFIData();
469 while (m_cfi_data.ValidOffsetForDataOfSize(offset, length: 8)) {
470 const dw_offset_t current_entry = offset;
471 dw_offset_t cie_id, next_entry, cie_offset;
472 uint32_t len = m_cfi_data.GetU32(offset_ptr: &offset);
473 bool is_64bit = (len == UINT32_MAX);
474 if (is_64bit) {
475 len = m_cfi_data.GetU64(offset_ptr: &offset);
476 cie_id = m_cfi_data.GetU64(offset_ptr: &offset);
477 next_entry = current_entry + len + 12;
478 cie_offset = current_entry + 12 - cie_id;
479 } else {
480 cie_id = m_cfi_data.GetU32(offset_ptr: &offset);
481 next_entry = current_entry + len + 4;
482 cie_offset = current_entry + 4 - cie_id;
483 }
484
485 if (next_entry > m_cfi_data.GetByteSize() + 1) {
486 Debugger::ReportError(message: llvm::formatv(Fmt: "Invalid fde/cie next entry offset "
487 "of {0:x} found in cie/fde at {1:x}",
488 Vals&: next_entry, Vals: current_entry));
489 // Don't trust anything in this eh_frame section if we find blatantly
490 // invalid data.
491 m_fde_index.Clear();
492 m_fde_index_initialized = true;
493 return;
494 }
495
496 // An FDE entry contains CIE_pointer in debug_frame in same place as cie_id
497 // in eh_frame. CIE_pointer is an offset into the .debug_frame section. So,
498 // variable cie_offset should be equal to cie_id for debug_frame.
499 // FDE entries with cie_id == 0 shouldn't be ignored for it.
500 if ((cie_id == 0 && m_type == EH) || cie_id == UINT32_MAX || len == 0) {
501 auto cie_sp = ParseCIE(cie_offset: current_entry);
502 if (!cie_sp) {
503 // Cannot parse, the reason is already logged
504 m_fde_index.Clear();
505 m_fde_index_initialized = true;
506 return;
507 }
508
509 m_cie_map[current_entry] = std::move(cie_sp);
510 offset = next_entry;
511 continue;
512 }
513
514 if (m_type == DWARF)
515 cie_offset = cie_id;
516
517 if (cie_offset > m_cfi_data.GetByteSize()) {
518 Debugger::ReportError(message: llvm::formatv(Fmt: "Invalid cie offset of {0:x} "
519 "found in cie/fde at {1:x}",
520 Vals&: cie_offset, Vals: current_entry));
521 // Don't trust anything in this eh_frame section if we find blatantly
522 // invalid data.
523 m_fde_index.Clear();
524 m_fde_index_initialized = true;
525 return;
526 }
527
528 const CIE *cie = GetCIE(cie_offset);
529 if (cie) {
530 const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
531 const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS;
532 const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS;
533
534 lldb::addr_t addr =
535 GetGNUEHPointer(DE: m_cfi_data, offset_ptr: &offset, eh_ptr_enc: cie->ptr_encoding, pc_rel_addr,
536 text_addr, data_addr);
537 if (clear_address_zeroth_bit)
538 addr &= ~1ull;
539
540 lldb::addr_t length = GetGNUEHPointer(
541 DE: m_cfi_data, offset_ptr: &offset, eh_ptr_enc: cie->ptr_encoding & DW_EH_PE_MASK_ENCODING,
542 pc_rel_addr, text_addr, data_addr);
543 FDEEntryMap::Entry fde(addr, length, current_entry);
544 m_fde_index.Append(entry: fde);
545 } else {
546 Debugger::ReportError(message: llvm::formatv(
547 Fmt: "unable to find CIE at {0:x} for cie_id = {1:x} for entry at {2:x}.",
548 Vals&: cie_offset, Vals&: cie_id, Vals: current_entry));
549 }
550 offset = next_entry;
551 }
552 m_fde_index.Sort();
553 m_fde_index_initialized = true;
554}
555
556std::optional<DWARFCallFrameInfo::FDE>
557DWARFCallFrameInfo::ParseFDE(dw_offset_t dwarf_offset,
558 const Address &startaddr) {
559 Log *log = GetLog(mask: LLDBLog::Unwind);
560 lldb::offset_t offset = dwarf_offset;
561 lldb::offset_t current_entry = offset;
562
563 if (!m_section_sp || m_section_sp->IsEncrypted())
564 return std::nullopt;
565
566 if (!m_cfi_data_initialized)
567 GetCFIData();
568
569 uint32_t length = m_cfi_data.GetU32(offset_ptr: &offset);
570 dw_offset_t cie_offset;
571 bool is_64bit = (length == UINT32_MAX);
572 if (is_64bit) {
573 length = m_cfi_data.GetU64(offset_ptr: &offset);
574 cie_offset = m_cfi_data.GetU64(offset_ptr: &offset);
575 } else {
576 cie_offset = m_cfi_data.GetU32(offset_ptr: &offset);
577 }
578
579 // FDE entries with zeroth cie_offset may occur for debug_frame.
580 assert(!(m_type == EH && 0 == cie_offset) && cie_offset != UINT32_MAX);
581
582 // Translate the CIE_id from the eh_frame format, which is relative to the
583 // FDE offset, into a __eh_frame section offset
584 if (m_type == EH)
585 cie_offset = current_entry + (is_64bit ? 12 : 4) - cie_offset;
586
587 const CIE *cie = GetCIE(cie_offset);
588 assert(cie != nullptr);
589
590 const dw_offset_t end_offset = current_entry + length + (is_64bit ? 12 : 4);
591
592 const lldb::addr_t pc_rel_addr = m_section_sp->GetFileAddress();
593 const lldb::addr_t text_addr = LLDB_INVALID_ADDRESS;
594 const lldb::addr_t data_addr = LLDB_INVALID_ADDRESS;
595 lldb::addr_t range_base =
596 GetGNUEHPointer(DE: m_cfi_data, offset_ptr: &offset, eh_ptr_enc: cie->ptr_encoding, pc_rel_addr,
597 text_addr, data_addr);
598 lldb::addr_t range_len = GetGNUEHPointer(
599 DE: m_cfi_data, offset_ptr: &offset, eh_ptr_enc: cie->ptr_encoding & DW_EH_PE_MASK_ENCODING,
600 pc_rel_addr, text_addr, data_addr);
601 AddressRange range(range_base, m_objfile.GetAddressByteSize(),
602 m_objfile.GetSectionList());
603 range.SetByteSize(range_len);
604
605 // Skip the LSDA, if present.
606 if (cie->augmentation[0] == 'z')
607 offset += (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
608
609 FDE fde;
610 fde.for_signal_trap = strchr(s: cie->augmentation, c: 'S') != nullptr;
611 fde.range = range;
612 fde.return_addr_reg_num = cie->return_addr_reg_num;
613
614 uint32_t code_align = cie->code_align;
615 int32_t data_align = cie->data_align;
616
617 UnwindPlan::Row row = cie->initial_row;
618 std::vector<UnwindPlan::Row> stack;
619
620 UnwindPlan::Row::AbstractRegisterLocation reg_location;
621 while (m_cfi_data.ValidOffset(offset) && offset < end_offset) {
622 uint8_t inst = m_cfi_data.GetU8(offset_ptr: &offset);
623 uint8_t primary_opcode = inst & 0xC0;
624 uint8_t extended_opcode = inst & 0x3F;
625
626 if (!HandleCommonDwarfOpcode(primary_opcode, extended_opcode, data_align,
627 offset, row)) {
628 if (primary_opcode) {
629 switch (primary_opcode) {
630 case DW_CFA_advance_loc: // (Row Creation Instruction)
631 { // 0x40 - high 2 bits are 0x1, lower 6 bits are delta
632 // takes a single argument that represents a constant delta. The
633 // required action is to create a new table row with a location value
634 // that is computed by taking the current entry's location value and
635 // adding (delta * code_align). All other values in the new row are
636 // initially identical to the current row.
637 fde.rows.push_back(x: row);
638 row.SlideOffset(offset: extended_opcode * code_align);
639 break;
640 }
641
642 case DW_CFA_restore: { // 0xC0 - high 2 bits are 0x3, lower 6 bits are
643 // register
644 // takes a single argument that represents a register number. The
645 // required action is to change the rule for the indicated register
646 // to the rule assigned it by the initial_instructions in the CIE.
647 uint32_t reg_num = extended_opcode;
648 // We only keep enough register locations around to unwind what is in
649 // our thread, and these are organized by the register index in that
650 // state, so we need to convert our eh_frame register number from the
651 // EH frame info, to a register index
652
653 if (fde.rows[0].GetRegisterInfo(reg_num, register_location&: reg_location))
654 row.SetRegisterInfo(reg_num, register_location: reg_location);
655 else {
656 // If the register was not set in the first row, remove the
657 // register info to keep the unmodified value from the caller.
658 row.RemoveRegisterInfo(reg_num);
659 }
660 break;
661 }
662 }
663 } else {
664 switch (extended_opcode) {
665 case DW_CFA_set_loc: // 0x1 (Row Creation Instruction)
666 {
667 // DW_CFA_set_loc takes a single argument that represents an address.
668 // The required action is to create a new table row using the
669 // specified address as the location. All other values in the new row
670 // are initially identical to the current row. The new location value
671 // should always be greater than the current one.
672 fde.rows.push_back(x: row);
673 row.SetOffset(m_cfi_data.GetAddress(offset_ptr: &offset) -
674 startaddr.GetFileAddress());
675 break;
676 }
677
678 case DW_CFA_advance_loc1: // 0x2 (Row Creation Instruction)
679 {
680 // takes a single uword argument that represents a constant delta.
681 // This instruction is identical to DW_CFA_advance_loc except for the
682 // encoding and size of the delta argument.
683 fde.rows.push_back(x: row);
684 row.SlideOffset(offset: m_cfi_data.GetU8(offset_ptr: &offset) * code_align);
685 break;
686 }
687
688 case DW_CFA_advance_loc2: // 0x3 (Row Creation Instruction)
689 {
690 // takes a single uword argument that represents a constant delta.
691 // This instruction is identical to DW_CFA_advance_loc except for the
692 // encoding and size of the delta argument.
693 fde.rows.push_back(x: row);
694 row.SlideOffset(offset: m_cfi_data.GetU16(offset_ptr: &offset) * code_align);
695 break;
696 }
697
698 case DW_CFA_advance_loc4: // 0x4 (Row Creation Instruction)
699 {
700 // takes a single uword argument that represents a constant delta.
701 // This instruction is identical to DW_CFA_advance_loc except for the
702 // encoding and size of the delta argument.
703 fde.rows.push_back(x: row);
704 row.SlideOffset(offset: m_cfi_data.GetU32(offset_ptr: &offset) * code_align);
705 break;
706 }
707
708 case DW_CFA_restore_extended: // 0x6
709 {
710 // takes a single unsigned LEB128 argument that represents a register
711 // number. This instruction is identical to DW_CFA_restore except for
712 // the encoding and size of the register argument.
713 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
714 if (fde.rows[0].GetRegisterInfo(reg_num, register_location&: reg_location))
715 row.SetRegisterInfo(reg_num, register_location: reg_location);
716 break;
717 }
718
719 case DW_CFA_remember_state: // 0xA
720 {
721 // These instructions define a stack of information. Encountering the
722 // DW_CFA_remember_state instruction means to save the rules for
723 // every register on the current row on the stack. Encountering the
724 // DW_CFA_restore_state instruction means to pop the set of rules off
725 // the stack and place them in the current row. (This operation is
726 // useful for compilers that move epilogue code into the body of a
727 // function.)
728 stack.push_back(x: row);
729 break;
730 }
731
732 case DW_CFA_restore_state: // 0xB
733 {
734 // These instructions define a stack of information. Encountering the
735 // DW_CFA_remember_state instruction means to save the rules for
736 // every register on the current row on the stack. Encountering the
737 // DW_CFA_restore_state instruction means to pop the set of rules off
738 // the stack and place them in the current row. (This operation is
739 // useful for compilers that move epilogue code into the body of a
740 // function.)
741 if (stack.empty()) {
742 LLDB_LOG(log,
743 "DWARFCallFrameInfo::{0}(dwarf_offset: "
744 "{1:x16}, startaddr: [{2:x16}] encountered "
745 "DW_CFA_restore_state but state stack "
746 "is empty. Corrupt unwind info?",
747 __FUNCTION__, dwarf_offset, startaddr.GetFileAddress());
748 break;
749 }
750 int64_t offset = row.GetOffset();
751 row = std::move(stack.back());
752 stack.pop_back();
753 row.SetOffset(offset);
754 break;
755 }
756
757 case DW_CFA_GNU_args_size: // 0x2e
758 {
759 // The DW_CFA_GNU_args_size instruction takes an unsigned LEB128
760 // operand representing an argument size. This instruction specifies
761 // the total of the size of the arguments which have been pushed onto
762 // the stack.
763
764 // TODO: Figure out how we should handle this.
765 m_cfi_data.GetULEB128(offset_ptr: &offset);
766 break;
767 }
768
769 case DW_CFA_val_offset: // 0x14
770 case DW_CFA_val_offset_sf: // 0x15
771 default:
772 break;
773 }
774 }
775 }
776 }
777 fde.rows.push_back(x: row);
778 return fde;
779}
780
781bool DWARFCallFrameInfo::HandleCommonDwarfOpcode(uint8_t primary_opcode,
782 uint8_t extended_opcode,
783 int32_t data_align,
784 lldb::offset_t &offset,
785 UnwindPlan::Row &row) {
786 UnwindPlan::Row::AbstractRegisterLocation reg_location;
787
788 if (primary_opcode) {
789 switch (primary_opcode) {
790 case DW_CFA_offset: { // 0x80 - high 2 bits are 0x2, lower 6 bits are
791 // register
792 // takes two arguments: an unsigned LEB128 constant representing a
793 // factored offset and a register number. The required action is to
794 // change the rule for the register indicated by the register number to
795 // be an offset(N) rule with a value of (N = factored offset *
796 // data_align).
797 uint8_t reg_num = extended_opcode;
798 int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(offset_ptr: &offset) * data_align;
799 reg_location.SetAtCFAPlusOffset(op_offset);
800 row.SetRegisterInfo(reg_num, register_location: reg_location);
801 return true;
802 }
803 }
804 } else {
805 switch (extended_opcode) {
806 case DW_CFA_nop: // 0x0
807 return true;
808
809 case DW_CFA_offset_extended: // 0x5
810 {
811 // takes two unsigned LEB128 arguments representing a register number and
812 // a factored offset. This instruction is identical to DW_CFA_offset
813 // except for the encoding and size of the register argument.
814 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
815 int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(offset_ptr: &offset) * data_align;
816 UnwindPlan::Row::AbstractRegisterLocation reg_location;
817 reg_location.SetAtCFAPlusOffset(op_offset);
818 row.SetRegisterInfo(reg_num, register_location: reg_location);
819 return true;
820 }
821
822 case DW_CFA_undefined: // 0x7
823 {
824 // takes a single unsigned LEB128 argument that represents a register
825 // number. The required action is to set the rule for the specified
826 // register to undefined.
827 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
828 UnwindPlan::Row::AbstractRegisterLocation reg_location;
829 reg_location.SetUndefined();
830 row.SetRegisterInfo(reg_num, register_location: reg_location);
831 return true;
832 }
833
834 case DW_CFA_same_value: // 0x8
835 {
836 // takes a single unsigned LEB128 argument that represents a register
837 // number. The required action is to set the rule for the specified
838 // register to same value.
839 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
840 UnwindPlan::Row::AbstractRegisterLocation reg_location;
841 reg_location.SetSame();
842 row.SetRegisterInfo(reg_num, register_location: reg_location);
843 return true;
844 }
845
846 case DW_CFA_register: // 0x9
847 {
848 // takes two unsigned LEB128 arguments representing register numbers. The
849 // required action is to set the rule for the first register to be the
850 // second register.
851 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
852 uint32_t other_reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
853 UnwindPlan::Row::AbstractRegisterLocation reg_location;
854 reg_location.SetInRegister(other_reg_num);
855 row.SetRegisterInfo(reg_num, register_location: reg_location);
856 return true;
857 }
858
859 case DW_CFA_def_cfa: // 0xC (CFA Definition Instruction)
860 {
861 // Takes two unsigned LEB128 operands representing a register number and
862 // a (non-factored) offset. The required action is to define the current
863 // CFA rule to use the provided register and offset.
864 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
865 int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
866 row.GetCFAValue().SetIsRegisterPlusOffset(reg_num, offset: op_offset);
867 return true;
868 }
869
870 case DW_CFA_def_cfa_register: // 0xD (CFA Definition Instruction)
871 {
872 // takes a single unsigned LEB128 argument representing a register
873 // number. The required action is to define the current CFA rule to use
874 // the provided register (but to keep the old offset).
875 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
876 row.GetCFAValue().SetIsRegisterPlusOffset(reg_num,
877 offset: row.GetCFAValue().GetOffset());
878 return true;
879 }
880
881 case DW_CFA_def_cfa_offset: // 0xE (CFA Definition Instruction)
882 {
883 // Takes a single unsigned LEB128 operand representing a (non-factored)
884 // offset. The required action is to define the current CFA rule to use
885 // the provided offset (but to keep the old register).
886 int32_t op_offset = (int32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
887 row.GetCFAValue().SetIsRegisterPlusOffset(
888 reg_num: row.GetCFAValue().GetRegisterNumber(), offset: op_offset);
889 return true;
890 }
891
892 case DW_CFA_def_cfa_expression: // 0xF (CFA Definition Instruction)
893 {
894 size_t block_len = (size_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
895 const uint8_t *block_data =
896 static_cast<const uint8_t *>(m_cfi_data.GetData(offset_ptr: &offset, length: block_len));
897 row.GetCFAValue().SetIsDWARFExpression(opcodes: block_data, len: block_len);
898 return true;
899 }
900
901 case DW_CFA_expression: // 0x10
902 {
903 // Takes two operands: an unsigned LEB128 value representing a register
904 // number, and a DW_FORM_block value representing a DWARF expression. The
905 // required action is to change the rule for the register indicated by
906 // the register number to be an expression(E) rule where E is the DWARF
907 // expression. That is, the DWARF expression computes the address. The
908 // value of the CFA is pushed on the DWARF evaluation stack prior to
909 // execution of the DWARF expression.
910 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
911 uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
912 const uint8_t *block_data =
913 static_cast<const uint8_t *>(m_cfi_data.GetData(offset_ptr: &offset, length: block_len));
914 UnwindPlan::Row::AbstractRegisterLocation reg_location;
915 reg_location.SetAtDWARFExpression(opcodes: block_data, len: block_len);
916 row.SetRegisterInfo(reg_num, register_location: reg_location);
917 return true;
918 }
919
920 case DW_CFA_offset_extended_sf: // 0x11
921 {
922 // takes two operands: an unsigned LEB128 value representing a register
923 // number and a signed LEB128 factored offset. This instruction is
924 // identical to DW_CFA_offset_extended except that the second operand is
925 // signed and factored.
926 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
927 int32_t op_offset = (int32_t)m_cfi_data.GetSLEB128(offset_ptr: &offset) * data_align;
928 UnwindPlan::Row::AbstractRegisterLocation reg_location;
929 reg_location.SetAtCFAPlusOffset(op_offset);
930 row.SetRegisterInfo(reg_num, register_location: reg_location);
931 return true;
932 }
933
934 case DW_CFA_def_cfa_sf: // 0x12 (CFA Definition Instruction)
935 {
936 // Takes two operands: an unsigned LEB128 value representing a register
937 // number and a signed LEB128 factored offset. This instruction is
938 // identical to DW_CFA_def_cfa except that the second operand is signed
939 // and factored.
940 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
941 int32_t op_offset = (int32_t)m_cfi_data.GetSLEB128(offset_ptr: &offset) * data_align;
942 row.GetCFAValue().SetIsRegisterPlusOffset(reg_num, offset: op_offset);
943 return true;
944 }
945
946 case DW_CFA_def_cfa_offset_sf: // 0x13 (CFA Definition Instruction)
947 {
948 // takes a signed LEB128 operand representing a factored offset. This
949 // instruction is identical to DW_CFA_def_cfa_offset except that the
950 // operand is signed and factored.
951 int32_t op_offset = (int32_t)m_cfi_data.GetSLEB128(offset_ptr: &offset) * data_align;
952 uint32_t cfa_regnum = row.GetCFAValue().GetRegisterNumber();
953 row.GetCFAValue().SetIsRegisterPlusOffset(reg_num: cfa_regnum, offset: op_offset);
954 return true;
955 }
956
957 case DW_CFA_val_expression: // 0x16
958 {
959 // takes two operands: an unsigned LEB128 value representing a register
960 // number, and a DW_FORM_block value representing a DWARF expression. The
961 // required action is to change the rule for the register indicated by
962 // the register number to be a val_expression(E) rule where E is the
963 // DWARF expression. That is, the DWARF expression computes the value of
964 // the given register. The value of the CFA is pushed on the DWARF
965 // evaluation stack prior to execution of the DWARF expression.
966 uint32_t reg_num = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
967 uint32_t block_len = (uint32_t)m_cfi_data.GetULEB128(offset_ptr: &offset);
968 const uint8_t *block_data =
969 (const uint8_t *)m_cfi_data.GetData(offset_ptr: &offset, length: block_len);
970 reg_location.SetIsDWARFExpression(opcodes: block_data, len: block_len);
971 row.SetRegisterInfo(reg_num, register_location: reg_location);
972 return true;
973 }
974 }
975 }
976 return false;
977}
978
979void DWARFCallFrameInfo::ForEachFDEEntries(
980 const std::function<bool(lldb::addr_t, uint32_t, dw_offset_t)> &callback) {
981 GetFDEIndex();
982
983 for (size_t i = 0, c = m_fde_index.GetSize(); i < c; ++i) {
984 const FDEEntryMap::Entry &entry = m_fde_index.GetEntryRef(i);
985 if (!callback(entry.base, entry.size, entry.data))
986 break;
987 }
988}
989

source code of lldb/source/Symbol/DWARFCallFrameInfo.cpp