1 //===- DWARFDebugRnglists.cpp ---------------------------------------------===//
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 #include "llvm/DebugInfo/DWARF/DWARFDebugRnglists.h"
11 #include "llvm/BinaryFormat/Dwarf.h"
12 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
13 #include "llvm/Support/Error.h"
14 #include "llvm/Support/Format.h"
15 #include "llvm/Support/raw_ostream.h"
16 
17 using namespace llvm;
18 
19 void DWARFDebugRnglistTable::clear() {
20   HeaderData = {};
21   Offsets.clear();
22   Ranges.clear();
23 }
24 
25 template <typename... Ts>
26 static Error createError(char const *Fmt, const Ts &... Vals) {
27   std::string Buffer;
28   raw_string_ostream Stream(Buffer);
29   Stream << format(Fmt, Vals...);
30   return make_error<StringError>(Stream.str(), inconvertibleErrorCode());
31 }
32 
33 Error DWARFDebugRnglistTable::extractHeaderAndOffsets(DWARFDataExtractor Data,
34                                                       uint32_t *OffsetPtr) {
35   HeaderOffset = *OffsetPtr;
36   // Read and verify the length field.
37   if (!Data.isValidOffsetForDataOfSize(*OffsetPtr, sizeof(uint32_t)))
38     return createError("section is not large enough to contain a "
39                        ".debug_rnglists table length at offset 0x%" PRIx32,
40                        *OffsetPtr);
41   // TODO: Add support for DWARF64.
42   HeaderData.Length = Data.getU32(OffsetPtr);
43   if (HeaderData.Length == 0xffffffffu)
44     return createError(
45         "DWARF64 is not supported in .debug_rnglists at offset 0x%" PRIx32,
46         HeaderOffset);
47   Format = dwarf::DwarfFormat::DWARF32;
48   if (HeaderData.Length + sizeof(uint32_t) < sizeof(Header))
49     return createError(".debug_rnglists table at offset 0x%" PRIx32
50                        " has too small length (0x%" PRIx32
51                        ") to contain a complete header",
52                        HeaderOffset, length());
53   uint32_t End = HeaderOffset + length();
54   if (!Data.isValidOffsetForDataOfSize(HeaderOffset, End - HeaderOffset))
55     return createError(
56         "section is not large enough to contain a .debug_rnglists table "
57         "of length 0x%" PRIx32 " at offset 0x%" PRIx32,
58         length(), HeaderOffset);
59 
60   HeaderData.Version = Data.getU16(OffsetPtr);
61   HeaderData.AddrSize = Data.getU8(OffsetPtr);
62   HeaderData.SegSize = Data.getU8(OffsetPtr);
63   HeaderData.OffsetEntryCount = Data.getU32(OffsetPtr);
64 
65   // Perform basic validation of the remaining header fields.
66   if (HeaderData.Version != 5)
67     return createError("unrecognised .debug_rnglists table version %" PRIu16
68                        " in table at offset 0x%" PRIx32,
69                        HeaderData.Version, HeaderOffset);
70   if (HeaderData.AddrSize != 4 && HeaderData.AddrSize != 8)
71     return createError(".debug_rnglists table at offset 0x%" PRIx32
72                        " has unsupported address size %hhu",
73                        HeaderOffset, HeaderData.AddrSize);
74   if (HeaderData.SegSize != 0)
75     return createError(".debug_rnglists table at offset 0x%" PRIx32
76                        " has unsupported segment selector size %" PRIu8,
77                        HeaderOffset, HeaderData.SegSize);
78   if (End < HeaderOffset + sizeof(HeaderData) +
79                 HeaderData.OffsetEntryCount * sizeof(uint32_t))
80     return createError(".debug_rnglists table at offset 0x%" PRIx32
81                        " has more offset entries (%" PRIu32
82                        ") than there is space for",
83                        HeaderOffset, HeaderData.OffsetEntryCount);
84   Data.setAddressSize(HeaderData.AddrSize);
85   for (uint32_t I = 0; I < HeaderData.OffsetEntryCount; ++I)
86     Offsets.push_back(Data.getU32(OffsetPtr));
87   return Error::success();
88 }
89 
90 Error DWARFDebugRnglist::RangeListEntry::extract(DWARFDataExtractor Data,
91                                                  uint32_t End,
92                                                  uint32_t *OffsetPtr) {
93   Offset = *OffsetPtr;
94   SectionIndex = -1ULL;
95   // The caller should guarantee that we have at least 1 byte available, so
96   // we just assert instead of revalidate.
97   assert(*OffsetPtr < End &&
98          "not enough space to extract a rangelist encoding");
99   uint8_t Encoding = Data.getU8(OffsetPtr);
100 
101   switch (Encoding) {
102   case dwarf::DW_RLE_end_of_list:
103     Value0 = Value1 = 0;
104     break;
105   // TODO: Support other encodings.
106   case dwarf::DW_RLE_base_addressx:
107     return createError("unsupported rnglists encoding DW_RLE_base_addressx "
108                        "at offset 0x%" PRIx32,
109                        *OffsetPtr - 1);
110   case dwarf::DW_RLE_startx_endx:
111     return createError("unsupported rnglists encoding DW_RLE_startx_endx at "
112                        "offset 0x%" PRIx32,
113                        *OffsetPtr - 1);
114   case dwarf::DW_RLE_startx_length:
115     return createError("unsupported rnglists encoding DW_RLE_startx_length "
116                        "at offset 0x%" PRIx32,
117                        *OffsetPtr - 1);
118   case dwarf::DW_RLE_offset_pair: {
119     uint32_t PreviousOffset = *OffsetPtr - 1;
120     Value0 = Data.getULEB128(OffsetPtr);
121     Value1 = Data.getULEB128(OffsetPtr);
122     if (End < *OffsetPtr)
123       return createError("read past end of table when reading "
124                          "DW_RLE_offset_pair encoding at offset 0x%" PRIx32,
125                          PreviousOffset);
126     break;
127   }
128   case dwarf::DW_RLE_base_address: {
129     if ((End - *OffsetPtr) < Data.getAddressSize())
130       return createError("insufficient space remaining in table for "
131                          "DW_RLE_base_address encoding at offset 0x%" PRIx32,
132                          *OffsetPtr - 1);
133     Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
134     break;
135   }
136   case dwarf::DW_RLE_start_end: {
137     if ((End - *OffsetPtr) < unsigned(Data.getAddressSize() * 2))
138       return createError("insufficient space remaining in table for "
139                          "DW_RLE_start_end encoding "
140                          "at offset 0x%" PRIx32,
141                          *OffsetPtr - 1);
142     Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
143     Value1 = Data.getRelocatedAddress(OffsetPtr);
144     break;
145   }
146   case dwarf::DW_RLE_start_length: {
147     uint32_t PreviousOffset = *OffsetPtr - 1;
148     Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
149     Value1 = Data.getULEB128(OffsetPtr);
150     if (End < *OffsetPtr)
151       return createError("read past end of table when reading "
152                          "DW_RLE_start_length encoding at offset 0x%" PRIx32,
153                          PreviousOffset);
154     break;
155   }
156   default:
157     return createError("unknown rnglists encoding 0x%" PRIx32
158                        " at offset 0x%" PRIx32,
159                        uint32_t(Encoding), *OffsetPtr - 1);
160   }
161 
162   EntryKind = Encoding;
163   return Error::success();
164 }
165 
166 DWARFAddressRangesVector DWARFDebugRnglist::getAbsoluteRanges(
167     llvm::Optional<BaseAddress> BaseAddr) const {
168   DWARFAddressRangesVector Res;
169   for (const RangeListEntry &RLE : Entries) {
170     if (RLE.EntryKind == dwarf::DW_RLE_end_of_list)
171       break;
172     if (RLE.EntryKind == dwarf::DW_RLE_base_address) {
173       BaseAddr = {RLE.Value0, RLE.SectionIndex};
174       continue;
175     }
176 
177     DWARFAddressRange E;
178     E.SectionIndex = RLE.SectionIndex;
179     if (BaseAddr && E.SectionIndex == -1ULL)
180       E.SectionIndex = BaseAddr->SectionIndex;
181 
182     switch (RLE.EntryKind) {
183     case dwarf::DW_RLE_offset_pair:
184       E.LowPC = RLE.Value0;
185       E.HighPC = RLE.Value1;
186       if (BaseAddr) {
187         E.LowPC += BaseAddr->Address;
188         E.HighPC += BaseAddr->Address;
189       }
190       break;
191     case dwarf::DW_RLE_start_end:
192       E.LowPC = RLE.Value0;
193       E.HighPC = RLE.Value1;
194       break;
195     case dwarf::DW_RLE_start_length:
196       E.LowPC = RLE.Value0;
197       E.HighPC = E.LowPC + RLE.Value1;
198       break;
199     default:
200       // Unsupported encodings should have been reported during extraction,
201       // so we should not run into any here.
202       llvm_unreachable("Unsupported range list encoding");
203     }
204     Res.push_back(E);
205   }
206   return Res;
207 }
208 
209 Error DWARFDebugRnglist::extract(DWARFDataExtractor Data, uint32_t HeaderOffset,
210                                  uint32_t End, uint32_t *OffsetPtr) {
211   Entries.clear();
212   while (*OffsetPtr < End) {
213     RangeListEntry Entry{0, 0, 0, 0, 0};
214     if (Error E = Entry.extract(Data, End, OffsetPtr))
215       return E;
216     Entries.push_back(Entry);
217     if (Entry.EntryKind == dwarf::DW_RLE_end_of_list)
218       return Error::success();
219   }
220   return createError(
221       "no end of list marker detected at end of .debug_rnglists table "
222       "starting at offset 0x%" PRIx32,
223       HeaderOffset);
224 }
225 
226 Error DWARFDebugRnglistTable::extract(DWARFDataExtractor Data,
227                                       uint32_t *OffsetPtr) {
228   clear();
229   if (Error E = extractHeaderAndOffsets(Data, OffsetPtr))
230     return E;
231 
232   Data.setAddressSize(HeaderData.AddrSize);
233   uint32_t End = HeaderOffset + length();
234   while (*OffsetPtr < End) {
235     DWARFDebugRnglist CurrentRangeList;
236     uint32_t Off = *OffsetPtr;
237     if (Error E = CurrentRangeList.extract(Data, HeaderOffset, End, OffsetPtr))
238       return E;
239     Ranges[Off] = CurrentRangeList;
240   }
241 
242   assert(*OffsetPtr == End &&
243          "mismatch between expected length of .debug_rnglists table and length "
244          "of extracted data");
245   return Error::success();
246 }
247 
248 static void dumpRangeEntry(raw_ostream &OS,
249                            DWARFDebugRnglist::RangeListEntry Entry,
250                            uint8_t AddrSize, uint8_t MaxEncodingStringLength,
251                            uint64_t &CurrentBase, DIDumpOptions DumpOpts) {
252   auto PrintRawEntry = [](raw_ostream &OS,
253                           DWARFDebugRnglist::RangeListEntry Entry,
254                           uint8_t AddrSize, DIDumpOptions DumpOpts) {
255     if (DumpOpts.Verbose) {
256       DumpOpts.DisplayRawContents = true;
257       DWARFAddressRange(Entry.Value0, Entry.Value1)
258           .dump(OS, AddrSize, DumpOpts);
259       OS << " => ";
260     }
261   };
262 
263   if (DumpOpts.Verbose) {
264     // Print the section offset in verbose mode.
265     OS << format("0x%8.8" PRIx32 ":", Entry.Offset);
266     auto EncodingString = dwarf::RangeListEncodingString(Entry.EntryKind);
267     // Unsupported encodings should have been reported during parsing.
268     assert(!EncodingString.empty() && "Unknown range entry encoding");
269     OS << format(" [%s%*c", EncodingString.data(),
270                  MaxEncodingStringLength - EncodingString.size() + 1, ']');
271     if (Entry.EntryKind != dwarf::DW_RLE_end_of_list)
272       OS << ": ";
273   }
274 
275   switch (Entry.EntryKind) {
276   case dwarf::DW_RLE_end_of_list:
277     OS << (DumpOpts.Verbose ? "" : "<End of list>");
278     break;
279   case dwarf::DW_RLE_base_address:
280     // In non-verbose mode we do not print anything for this entry.
281     CurrentBase = Entry.Value0;
282     if (!DumpOpts.Verbose)
283       return;
284     OS << format(" 0x%*.*" PRIx64, AddrSize * 2, AddrSize * 2, Entry.Value0);
285     break;
286   case dwarf::DW_RLE_start_length:
287     PrintRawEntry(OS, Entry, AddrSize, DumpOpts);
288     DWARFAddressRange(Entry.Value0, Entry.Value0 + Entry.Value1)
289         .dump(OS, AddrSize, DumpOpts);
290     break;
291   case dwarf::DW_RLE_offset_pair:
292     PrintRawEntry(OS, Entry, AddrSize, DumpOpts);
293     DWARFAddressRange(Entry.Value0 + CurrentBase, Entry.Value1 + CurrentBase)
294         .dump(OS, AddrSize, DumpOpts);
295     break;
296   case dwarf::DW_RLE_start_end:
297     DWARFAddressRange(Entry.Value0, Entry.Value1).dump(OS, AddrSize, DumpOpts);
298     break;
299   default:
300     llvm_unreachable("Unsupported range list encoding");
301   }
302   OS << "\n";
303 }
304 
305 void DWARFDebugRnglistTable::dump(raw_ostream &OS,
306                                   DIDumpOptions DumpOpts) const {
307   if (DumpOpts.Verbose)
308     OS << format("0x%8.8" PRIx32 ": ", HeaderOffset);
309   OS << format("Range List Header: length = 0x%8.8" PRIx32
310                ", version = 0x%4.4" PRIx16 ", "
311                "addr_size = 0x%2.2" PRIx8 ", seg_size = 0x%2.2" PRIx8
312                ", offset_entry_count = "
313                "0x%8.8" PRIx32 "\n",
314                HeaderData.Length, HeaderData.Version, HeaderData.AddrSize,
315                HeaderData.SegSize, HeaderData.OffsetEntryCount);
316 
317   if (HeaderData.OffsetEntryCount > 0) {
318     OS << "Offsets: [";
319     for (const auto &Off : Offsets) {
320       OS << format("\n0x%8.8" PRIx32, Off);
321       if (DumpOpts.Verbose)
322         OS << format(" => 0x%8.8" PRIx32,
323                      Off + HeaderOffset + sizeof(HeaderData));
324     }
325     OS << "\n]\n";
326   }
327   OS << "Ranges:\n";
328 
329   // Determine the length of the longest encoding string we have in the table,
330   // so we can align the output properly. We only need this in verbose mode.
331   size_t MaxEncodingStringLength = 0;
332   if (DumpOpts.Verbose) {
333     for (const auto &List : Ranges)
334       for (const auto &Entry : List.second.getEntries())
335         MaxEncodingStringLength =
336             std::max(MaxEncodingStringLength,
337                      dwarf::RangeListEncodingString(Entry.EntryKind).size());
338   }
339 
340   uint64_t CurrentBase = 0;
341   for (const auto &List : Ranges)
342     for (const auto &Entry : List.second.getEntries())
343       dumpRangeEntry(OS, Entry, HeaderData.AddrSize, MaxEncodingStringLength,
344                      CurrentBase, DumpOpts);
345 }
346 
347 uint32_t DWARFDebugRnglistTable::length() const {
348   if (HeaderData.Length == 0)
349     return 0;
350   // TODO: DWARF64 support.
351   return HeaderData.Length + sizeof(uint32_t);
352 }
353 
354 Optional<DWARFDebugRnglist>
355 DWARFDebugRnglistTable::findRangeList(DWARFDataExtractor Data,
356                                       uint32_t Offset) {
357   auto Entry = Ranges.find(Offset);
358   if (Entry != Ranges.end())
359     return Entry->second;
360 
361   // Extract the rangelist from the section and enter it into the ranges map.
362   DWARFDebugRnglist RngList;
363   uint32_t End = HeaderOffset + length();
364   uint32_t StartingOffset = Offset;
365   if (Error E = RngList.extract(Data, HeaderOffset, End, &Offset)) {
366     llvm::consumeError(std::move(E));
367     return None;
368   }
369   Ranges[StartingOffset] = RngList;
370   return RngList;
371 }
372