1//===- DWARFDebugLoc.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 "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
10#include "llvm/ADT/StringRef.h"
11#include "llvm/BinaryFormat/Dwarf.h"
12#include "llvm/DebugInfo/DWARF/DWARFContext.h"
13#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
14#include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
15#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
16#include "llvm/Support/Compiler.h"
17#include "llvm/Support/Format.h"
18#include "llvm/Support/WithColor.h"
19#include "llvm/Support/raw_ostream.h"
20#include <algorithm>
21#include <cinttypes>
22#include <cstdint>
23
24using namespace llvm;
25using object::SectionedAddress;
26
27namespace {
28class DWARFLocationInterpreter {
29  Optional<object::SectionedAddress> Base;
30  std::function<Optional<object::SectionedAddress>(uint32_t)> LookupAddr;
31
32public:
33  DWARFLocationInterpreter(
34      Optional<object::SectionedAddress> Base,
35      std::function<Optional<object::SectionedAddress>(uint32_t)> LookupAddr)
36      : Base(Base), LookupAddr(std::move(LookupAddr)) {}
37
38  Expected<Optional<DWARFLocationExpression>>
39  Interpret(const DWARFLocationEntry &E);
40};
41} // namespace
42
43static Error createResolverError(uint32_t Index, unsigned Kind) {
44  return createStringError(errc::invalid_argument,
45                           "Unable to resolve indirect address %u for: %s",
46                           Index, dwarf::LocListEncodingString(Kind).data());
47}
48
49Expected<Optional<DWARFLocationExpression>>
50DWARFLocationInterpreter::Interpret(const DWARFLocationEntry &E) {
51  switch (E.Kind) {
52  case dwarf::DW_LLE_end_of_list:
53    return None;
54  case dwarf::DW_LLE_base_addressx: {
55    Base = LookupAddr(E.Value0);
56    if (!Base)
57      return createResolverError(E.Value0, E.Kind);
58    return None;
59  }
60  case dwarf::DW_LLE_startx_endx: {
61    Optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
62    if (!LowPC)
63      return createResolverError(E.Value0, E.Kind);
64    Optional<SectionedAddress> HighPC = LookupAddr(E.Value1);
65    if (!HighPC)
66      return createResolverError(E.Value1, E.Kind);
67    return DWARFLocationExpression{
68        DWARFAddressRange{LowPC->Address, HighPC->Address, LowPC->SectionIndex},
69        E.Loc};
70  }
71  case dwarf::DW_LLE_startx_length: {
72    Optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
73    if (!LowPC)
74      return createResolverError(E.Value0, E.Kind);
75    return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
76                                                     LowPC->Address + E.Value1,
77                                                     LowPC->SectionIndex},
78                                   E.Loc};
79  }
80  case dwarf::DW_LLE_offset_pair: {
81    if (!Base) {
82      return createStringError(inconvertibleErrorCode(),
83                               "Unable to resolve location list offset pair: "
84                               "Base address not defined");
85    }
86    DWARFAddressRange Range{Base->Address + E.Value0, Base->Address + E.Value1,
87                            Base->SectionIndex};
88    if (Range.SectionIndex == SectionedAddress::UndefSection)
89      Range.SectionIndex = E.SectionIndex;
90    return DWARFLocationExpression{Range, E.Loc};
91  }
92  case dwarf::DW_LLE_default_location:
93    return DWARFLocationExpression{None, E.Loc};
94  case dwarf::DW_LLE_base_address:
95    Base = SectionedAddress{E.Value0, E.SectionIndex};
96    return None;
97  case dwarf::DW_LLE_start_end:
98    return DWARFLocationExpression{
99        DWARFAddressRange{E.Value0, E.Value1, E.SectionIndex}, E.Loc};
100  case dwarf::DW_LLE_start_length:
101    return DWARFLocationExpression{
102        DWARFAddressRange{E.Value0, E.Value0 + E.Value1, E.SectionIndex},
103        E.Loc};
104  default:
105    llvm_unreachable("unreachable locations list kind");
106  }
107}
108
109static void dumpExpression(raw_ostream &OS, ArrayRef<uint8_t> Data,
110                           bool IsLittleEndian, unsigned AddressSize,
111                           const MCRegisterInfo *MRI, DWARFUnit *U) {
112  DWARFDataExtractor Extractor(Data, IsLittleEndian, AddressSize);
113  // Note. We do not pass any format to DWARFExpression, even if the
114  // corresponding unit is known. For now, there is only one operation,
115  // DW_OP_call_ref, which depends on the format; it is rarely used, and
116  // is unexpected in location tables.
117  DWARFExpression(Extractor, AddressSize).print(OS, MRI, U);
118}
119
120bool DWARFLocationTable::dumpLocationList(uint64_t *Offset, raw_ostream &OS,
121                                          Optional<SectionedAddress> BaseAddr,
122                                          const MCRegisterInfo *MRI,
123                                          const DWARFObject &Obj, DWARFUnit *U,
124                                          DIDumpOptions DumpOpts,
125                                          unsigned Indent) const {
126  DWARFLocationInterpreter Interp(
127      BaseAddr, [U](uint32_t Index) -> Optional<SectionedAddress> {
128        if (U)
129          return U->getAddrOffsetSectionItem(Index);
130        return None;
131      });
132  OS << format("0x%8.8" PRIx64 ": ", *Offset);
133  Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
134    Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
135    if (!Loc || DumpOpts.DisplayRawContents)
136      dumpRawEntry(E, OS, Indent, DumpOpts, Obj);
137    if (Loc && *Loc) {
138      OS << "\n";
139      OS.indent(Indent);
140      if (DumpOpts.DisplayRawContents)
141        OS << "          => ";
142
143      DIDumpOptions RangeDumpOpts(DumpOpts);
144      RangeDumpOpts.DisplayRawContents = false;
145      if (Loc.get()->Range)
146        Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, &Obj);
147      else
148        OS << "<default>";
149    }
150    if (!Loc)
151      consumeError(Loc.takeError());
152
153    if (E.Kind != dwarf::DW_LLE_base_address &&
154        E.Kind != dwarf::DW_LLE_base_addressx &&
155        E.Kind != dwarf::DW_LLE_end_of_list) {
156      OS << ": ";
157      dumpExpression(OS, E.Loc, Data.isLittleEndian(), Data.getAddressSize(),
158                     MRI, U);
159    }
160    return true;
161  });
162  if (E) {
163    DumpOpts.RecoverableErrorHandler(std::move(E));
164    return false;
165  }
166  return true;
167}
168
169Error DWARFLocationTable::visitAbsoluteLocationList(
170    uint64_t Offset, Optional<SectionedAddress> BaseAddr,
171    std::function<Optional<SectionedAddress>(uint32_t)> LookupAddr,
172    function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
173  DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
174  return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
175    Expected<Optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
176    if (!Loc)
177      return Callback(Loc.takeError());
178    if (*Loc)
179      return Callback(**Loc);
180    return true;
181  });
182}
183
184void DWARFDebugLoc::dump(raw_ostream &OS, const MCRegisterInfo *MRI,
185                         const DWARFObject &Obj, DIDumpOptions DumpOpts,
186                         Optional<uint64_t> DumpOffset) const {
187  auto BaseAddr = None;
188  unsigned Indent = 12;
189  if (DumpOffset) {
190    dumpLocationList(&*DumpOffset, OS, BaseAddr, MRI, Obj, nullptr, DumpOpts,
191                     Indent);
192  } else {
193    uint64_t Offset = 0;
194    StringRef Separator;
195    bool CanContinue = true;
196    while (CanContinue && Data.isValidOffset(Offset)) {
197      OS << Separator;
198      Separator = "\n";
199
200      CanContinue = dumpLocationList(&Offset, OS, BaseAddr, MRI, Obj, nullptr,
201                                     DumpOpts, Indent);
202      OS << '\n';
203    }
204  }
205}
206
207Error DWARFDebugLoc::visitLocationList(
208    uint64_t *Offset,
209    function_ref<bool(const DWARFLocationEntry &)> Callback) const {
210  DataExtractor::Cursor C(*Offset);
211  while (true) {
212    uint64_t SectionIndex;
213    uint64_t Value0 = Data.getRelocatedAddress(C);
214    uint64_t Value1 = Data.getRelocatedAddress(C, &SectionIndex);
215
216    DWARFLocationEntry E;
217
218    // The end of any given location list is marked by an end of list entry,
219    // which consists of a 0 for the beginning address offset and a 0 for the
220    // ending address offset. A beginning offset of 0xff...f marks the base
221    // address selection entry.
222    if (Value0 == 0 && Value1 == 0) {
223      E.Kind = dwarf::DW_LLE_end_of_list;
224    } else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
225      E.Kind = dwarf::DW_LLE_base_address;
226      E.Value0 = Value1;
227      E.SectionIndex = SectionIndex;
228    } else {
229      E.Kind = dwarf::DW_LLE_offset_pair;
230      E.Value0 = Value0;
231      E.Value1 = Value1;
232      E.SectionIndex = SectionIndex;
233      unsigned Bytes = Data.getU16(C);
234      // A single location description describing the location of the object...
235      Data.getU8(C, E.Loc, Bytes);
236    }
237
238    if (!C)
239      return C.takeError();
240    if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
241      break;
242  }
243  *Offset = C.tell();
244  return Error::success();
245}
246
247void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
248                                 raw_ostream &OS, unsigned Indent,
249                                 DIDumpOptions DumpOpts,
250                                 const DWARFObject &Obj) const {
251  uint64_t Value0, Value1;
252  switch (Entry.Kind) {
253  case dwarf::DW_LLE_base_address:
254    Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
255    Value1 = Entry.Value0;
256    break;
257  case dwarf::DW_LLE_offset_pair:
258    Value0 = Entry.Value0;
259    Value1 = Entry.Value1;
260    break;
261  case dwarf::DW_LLE_end_of_list:
262    Value0 = Value1 = 0;
263    return;
264  default:
265    llvm_unreachable("Not possible in DWARF4!");
266  }
267  OS << '\n';
268  OS.indent(Indent);
269  OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
270     << format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
271  DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
272}
273
274Error DWARFDebugLoclists::visitLocationList(
275    uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
276
277  DataExtractor::Cursor C(*Offset);
278  bool Continue = true;
279  while (Continue) {
280    DWARFLocationEntry E;
281    E.Kind = Data.getU8(C);
282    switch (E.Kind) {
283    case dwarf::DW_LLE_end_of_list:
284      break;
285    case dwarf::DW_LLE_base_addressx:
286      E.Value0 = Data.getULEB128(C);
287      break;
288    case dwarf::DW_LLE_startx_endx:
289      E.Value0 = Data.getULEB128(C);
290      E.Value1 = Data.getULEB128(C);
291      break;
292    case dwarf::DW_LLE_startx_length:
293      E.Value0 = Data.getULEB128(C);
294      // Pre-DWARF 5 has different interpretation of the length field. We have
295      // to support both pre- and standartized styles for the compatibility.
296      if (Version < 5)
297        E.Value1 = Data.getU32(C);
298      else
299        E.Value1 = Data.getULEB128(C);
300      break;
301    case dwarf::DW_LLE_offset_pair:
302      E.Value0 = Data.getULEB128(C);
303      E.Value1 = Data.getULEB128(C);
304      E.SectionIndex = SectionedAddress::UndefSection;
305      break;
306    case dwarf::DW_LLE_default_location:
307      break;
308    case dwarf::DW_LLE_base_address:
309      E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
310      break;
311    case dwarf::DW_LLE_start_end:
312      E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
313      E.Value1 = Data.getRelocatedAddress(C);
314      break;
315    case dwarf::DW_LLE_start_length:
316      E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
317      E.Value1 = Data.getULEB128(C);
318      break;
319    default:
320      cantFail(C.takeError());
321      return createStringError(errc::illegal_byte_sequence,
322                               "LLE of kind %x not supported", (int)E.Kind);
323    }
324
325    if (E.Kind != dwarf::DW_LLE_base_address &&
326        E.Kind != dwarf::DW_LLE_base_addressx &&
327        E.Kind != dwarf::DW_LLE_end_of_list) {
328      unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
329      // A single location description describing the location of the object...
330      Data.getU8(C, E.Loc, Bytes);
331    }
332
333    if (!C)
334      return C.takeError();
335    Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
336  }
337  *Offset = C.tell();
338  return Error::success();
339}
340
341void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
342                                      raw_ostream &OS, unsigned Indent,
343                                      DIDumpOptions DumpOpts,
344                                      const DWARFObject &Obj) const {
345  size_t MaxEncodingStringLength = 0;
346#define HANDLE_DW_LLE(ID, NAME)                                                \
347  MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
348                                     dwarf::LocListEncodingString(ID).size());
349#include "llvm/BinaryFormat/Dwarf.def"
350
351  OS << "\n";
352  OS.indent(Indent);
353  StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
354  // Unsupported encodings should have been reported during parsing.
355  assert(!EncodingString.empty() && "Unknown loclist entry encoding");
356  OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
357  unsigned FieldSize = 2 + 2 * Data.getAddressSize();
358  switch (Entry.Kind) {
359  case dwarf::DW_LLE_end_of_list:
360  case dwarf::DW_LLE_default_location:
361    break;
362  case dwarf::DW_LLE_startx_endx:
363  case dwarf::DW_LLE_startx_length:
364  case dwarf::DW_LLE_offset_pair:
365  case dwarf::DW_LLE_start_end:
366  case dwarf::DW_LLE_start_length:
367    OS << format_hex(Entry.Value0, FieldSize) << ", "
368       << format_hex(Entry.Value1, FieldSize);
369    break;
370  case dwarf::DW_LLE_base_addressx:
371  case dwarf::DW_LLE_base_address:
372    OS << format_hex(Entry.Value0, FieldSize);
373    break;
374  }
375  OS << ')';
376  switch (Entry.Kind) {
377  case dwarf::DW_LLE_base_address:
378  case dwarf::DW_LLE_start_end:
379  case dwarf::DW_LLE_start_length:
380    DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
381    break;
382  default:
383    break;
384  }
385}
386
387void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
388                                   raw_ostream &OS, const MCRegisterInfo *MRI,
389                                   const DWARFObject &Obj,
390                                   DIDumpOptions DumpOpts) {
391  if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
392    OS << "Invalid dump range\n";
393    return;
394  }
395  uint64_t Offset = StartOffset;
396  StringRef Separator;
397  bool CanContinue = true;
398  while (CanContinue && Offset < StartOffset + Size) {
399    OS << Separator;
400    Separator = "\n";
401
402    CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/None, MRI, Obj,
403                                   nullptr, DumpOpts, /*Indent=*/12);
404    OS << '\n';
405  }
406}
407