1 //===- ELF.cpp - ELF object file implementation ---------------------------===//
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/Object/ELF.h"
10 #include "llvm/BinaryFormat/ELF.h"
11 #include "llvm/Support/DataExtractor.h"
12 
13 using namespace llvm;
14 using namespace object;
15 
16 #define STRINGIFY_ENUM_CASE(ns, name)                                          \
17   case ns::name:                                                               \
18     return #name;
19 
20 #define ELF_RELOC(name, value) STRINGIFY_ENUM_CASE(ELF, name)
21 
22 StringRef llvm::object::getELFRelocationTypeName(uint32_t Machine,
23                                                  uint32_t Type) {
24   switch (Machine) {
25   case ELF::EM_68K:
26     switch (Type) {
27 #include "llvm/BinaryFormat/ELFRelocs/M68k.def"
28     default:
29       break;
30     }
31     break;
32   case ELF::EM_X86_64:
33     switch (Type) {
34 #include "llvm/BinaryFormat/ELFRelocs/x86_64.def"
35     default:
36       break;
37     }
38     break;
39   case ELF::EM_386:
40   case ELF::EM_IAMCU:
41     switch (Type) {
42 #include "llvm/BinaryFormat/ELFRelocs/i386.def"
43     default:
44       break;
45     }
46     break;
47   case ELF::EM_MIPS:
48     switch (Type) {
49 #include "llvm/BinaryFormat/ELFRelocs/Mips.def"
50     default:
51       break;
52     }
53     break;
54   case ELF::EM_AARCH64:
55     switch (Type) {
56 #include "llvm/BinaryFormat/ELFRelocs/AArch64.def"
57     default:
58       break;
59     }
60     break;
61   case ELF::EM_ARM:
62     switch (Type) {
63 #include "llvm/BinaryFormat/ELFRelocs/ARM.def"
64     default:
65       break;
66     }
67     break;
68   case ELF::EM_ARC_COMPACT:
69   case ELF::EM_ARC_COMPACT2:
70     switch (Type) {
71 #include "llvm/BinaryFormat/ELFRelocs/ARC.def"
72     default:
73       break;
74     }
75     break;
76   case ELF::EM_AVR:
77     switch (Type) {
78 #include "llvm/BinaryFormat/ELFRelocs/AVR.def"
79     default:
80       break;
81     }
82     break;
83   case ELF::EM_HEXAGON:
84     switch (Type) {
85 #include "llvm/BinaryFormat/ELFRelocs/Hexagon.def"
86     default:
87       break;
88     }
89     break;
90   case ELF::EM_LANAI:
91     switch (Type) {
92 #include "llvm/BinaryFormat/ELFRelocs/Lanai.def"
93     default:
94       break;
95     }
96     break;
97   case ELF::EM_PPC:
98     switch (Type) {
99 #include "llvm/BinaryFormat/ELFRelocs/PowerPC.def"
100     default:
101       break;
102     }
103     break;
104   case ELF::EM_PPC64:
105     switch (Type) {
106 #include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def"
107     default:
108       break;
109     }
110     break;
111   case ELF::EM_RISCV:
112     switch (Type) {
113 #include "llvm/BinaryFormat/ELFRelocs/RISCV.def"
114     default:
115       break;
116     }
117     break;
118   case ELF::EM_S390:
119     switch (Type) {
120 #include "llvm/BinaryFormat/ELFRelocs/SystemZ.def"
121     default:
122       break;
123     }
124     break;
125   case ELF::EM_SPARC:
126   case ELF::EM_SPARC32PLUS:
127   case ELF::EM_SPARCV9:
128     switch (Type) {
129 #include "llvm/BinaryFormat/ELFRelocs/Sparc.def"
130     default:
131       break;
132     }
133     break;
134   case ELF::EM_AMDGPU:
135     switch (Type) {
136 #include "llvm/BinaryFormat/ELFRelocs/AMDGPU.def"
137     default:
138       break;
139     }
140     break;
141   case ELF::EM_BPF:
142     switch (Type) {
143 #include "llvm/BinaryFormat/ELFRelocs/BPF.def"
144     default:
145       break;
146     }
147     break;
148   case ELF::EM_MSP430:
149     switch (Type) {
150 #include "llvm/BinaryFormat/ELFRelocs/MSP430.def"
151     default:
152       break;
153     }
154     break;
155   case ELF::EM_VE:
156     switch (Type) {
157 #include "llvm/BinaryFormat/ELFRelocs/VE.def"
158     default:
159       break;
160     }
161     break;
162   case ELF::EM_CSKY:
163     switch (Type) {
164 #include "llvm/BinaryFormat/ELFRelocs/CSKY.def"
165     default:
166       break;
167     }
168     break;
169   case ELF::EM_LOONGARCH:
170     switch (Type) {
171 #include "llvm/BinaryFormat/ELFRelocs/LoongArch.def"
172     default:
173       break;
174     }
175     break;
176   case ELF::EM_XTENSA:
177     switch (Type) {
178 #include "llvm/BinaryFormat/ELFRelocs/Xtensa.def"
179     default:
180       break;
181     }
182     break;
183   default:
184     break;
185   }
186   return "Unknown";
187 }
188 
189 #undef ELF_RELOC
190 
191 uint32_t llvm::object::getELFRelativeRelocationType(uint32_t Machine) {
192   switch (Machine) {
193   case ELF::EM_X86_64:
194     return ELF::R_X86_64_RELATIVE;
195   case ELF::EM_386:
196   case ELF::EM_IAMCU:
197     return ELF::R_386_RELATIVE;
198   case ELF::EM_MIPS:
199     break;
200   case ELF::EM_AARCH64:
201     return ELF::R_AARCH64_RELATIVE;
202   case ELF::EM_ARM:
203     return ELF::R_ARM_RELATIVE;
204   case ELF::EM_ARC_COMPACT:
205   case ELF::EM_ARC_COMPACT2:
206     return ELF::R_ARC_RELATIVE;
207   case ELF::EM_AVR:
208     break;
209   case ELF::EM_HEXAGON:
210     return ELF::R_HEX_RELATIVE;
211   case ELF::EM_LANAI:
212     break;
213   case ELF::EM_PPC:
214     break;
215   case ELF::EM_PPC64:
216     return ELF::R_PPC64_RELATIVE;
217   case ELF::EM_RISCV:
218     return ELF::R_RISCV_RELATIVE;
219   case ELF::EM_S390:
220     return ELF::R_390_RELATIVE;
221   case ELF::EM_SPARC:
222   case ELF::EM_SPARC32PLUS:
223   case ELF::EM_SPARCV9:
224     return ELF::R_SPARC_RELATIVE;
225   case ELF::EM_CSKY:
226     return ELF::R_CKCORE_RELATIVE;
227   case ELF::EM_VE:
228     return ELF::R_VE_RELATIVE;
229   case ELF::EM_AMDGPU:
230     break;
231   case ELF::EM_BPF:
232     break;
233   case ELF::EM_LOONGARCH:
234     return ELF::R_LARCH_RELATIVE;
235   default:
236     break;
237   }
238   return 0;
239 }
240 
241 StringRef llvm::object::getELFSectionTypeName(uint32_t Machine, unsigned Type) {
242   switch (Machine) {
243   case ELF::EM_ARM:
244     switch (Type) {
245       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_EXIDX);
246       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_PREEMPTMAP);
247       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_ATTRIBUTES);
248       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_DEBUGOVERLAY);
249       STRINGIFY_ENUM_CASE(ELF, SHT_ARM_OVERLAYSECTION);
250     }
251     break;
252   case ELF::EM_HEXAGON:
253     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_HEX_ORDERED); }
254     break;
255   case ELF::EM_X86_64:
256     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_X86_64_UNWIND); }
257     break;
258   case ELF::EM_MIPS:
259   case ELF::EM_MIPS_RS3_LE:
260     switch (Type) {
261       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_REGINFO);
262       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_OPTIONS);
263       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_DWARF);
264       STRINGIFY_ENUM_CASE(ELF, SHT_MIPS_ABIFLAGS);
265     }
266     break;
267   case ELF::EM_MSP430:
268     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_MSP430_ATTRIBUTES); }
269     break;
270   case ELF::EM_RISCV:
271     switch (Type) { STRINGIFY_ENUM_CASE(ELF, SHT_RISCV_ATTRIBUTES); }
272     break;
273   default:
274     break;
275   }
276 
277   switch (Type) {
278     STRINGIFY_ENUM_CASE(ELF, SHT_NULL);
279     STRINGIFY_ENUM_CASE(ELF, SHT_PROGBITS);
280     STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB);
281     STRINGIFY_ENUM_CASE(ELF, SHT_STRTAB);
282     STRINGIFY_ENUM_CASE(ELF, SHT_RELA);
283     STRINGIFY_ENUM_CASE(ELF, SHT_HASH);
284     STRINGIFY_ENUM_CASE(ELF, SHT_DYNAMIC);
285     STRINGIFY_ENUM_CASE(ELF, SHT_NOTE);
286     STRINGIFY_ENUM_CASE(ELF, SHT_NOBITS);
287     STRINGIFY_ENUM_CASE(ELF, SHT_REL);
288     STRINGIFY_ENUM_CASE(ELF, SHT_SHLIB);
289     STRINGIFY_ENUM_CASE(ELF, SHT_DYNSYM);
290     STRINGIFY_ENUM_CASE(ELF, SHT_INIT_ARRAY);
291     STRINGIFY_ENUM_CASE(ELF, SHT_FINI_ARRAY);
292     STRINGIFY_ENUM_CASE(ELF, SHT_PREINIT_ARRAY);
293     STRINGIFY_ENUM_CASE(ELF, SHT_GROUP);
294     STRINGIFY_ENUM_CASE(ELF, SHT_SYMTAB_SHNDX);
295     STRINGIFY_ENUM_CASE(ELF, SHT_RELR);
296     STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_REL);
297     STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELA);
298     STRINGIFY_ENUM_CASE(ELF, SHT_ANDROID_RELR);
299     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ODRTAB);
300     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_LINKER_OPTIONS);
301     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_CALL_GRAPH_PROFILE);
302     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_ADDRSIG);
303     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_DEPENDENT_LIBRARIES);
304     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_SYMPART);
305     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_EHDR);
306     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_PART_PHDR);
307     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP_V0);
308     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_BB_ADDR_MAP);
309     STRINGIFY_ENUM_CASE(ELF, SHT_LLVM_OFFLOADING);
310     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_ATTRIBUTES);
311     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_HASH);
312     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verdef);
313     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_verneed);
314     STRINGIFY_ENUM_CASE(ELF, SHT_GNU_versym);
315   default:
316     return "Unknown";
317   }
318 }
319 
320 template <class ELFT>
321 std::vector<typename ELFT::Rel>
322 ELFFile<ELFT>::decode_relrs(Elf_Relr_Range relrs) const {
323   // This function decodes the contents of an SHT_RELR packed relocation
324   // section.
325   //
326   // Proposal for adding SHT_RELR sections to generic-abi is here:
327   //   https://groups.google.com/forum/#!topic/generic-abi/bX460iggiKg
328   //
329   // The encoded sequence of Elf64_Relr entries in a SHT_RELR section looks
330   // like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ]
331   //
332   // i.e. start with an address, followed by any number of bitmaps. The address
333   // entry encodes 1 relocation. The subsequent bitmap entries encode up to 63
334   // relocations each, at subsequent offsets following the last address entry.
335   //
336   // The bitmap entries must have 1 in the least significant bit. The assumption
337   // here is that an address cannot have 1 in lsb. Odd addresses are not
338   // supported.
339   //
340   // Excluding the least significant bit in the bitmap, each non-zero bit in
341   // the bitmap represents a relocation to be applied to a corresponding machine
342   // word that follows the base address word. The second least significant bit
343   // represents the machine word immediately following the initial address, and
344   // each bit that follows represents the next word, in linear order. As such,
345   // a single bitmap can encode up to 31 relocations in a 32-bit object, and
346   // 63 relocations in a 64-bit object.
347   //
348   // This encoding has a couple of interesting properties:
349   // 1. Looking at any entry, it is clear whether it's an address or a bitmap:
350   //    even means address, odd means bitmap.
351   // 2. Just a simple list of addresses is a valid encoding.
352 
353   Elf_Rel Rel;
354   Rel.r_info = 0;
355   Rel.setType(getRelativeRelocationType(), false);
356   std::vector<Elf_Rel> Relocs;
357 
358   // Word type: uint32_t for Elf32, and uint64_t for Elf64.
359   using Addr = typename ELFT::uint;
360 
361   Addr Base = 0;
362   for (Elf_Relr R : relrs) {
363     typename ELFT::uint Entry = R;
364     if ((Entry & 1) == 0) {
365       // Even entry: encodes the offset for next relocation.
366       Rel.r_offset = Entry;
367       Relocs.push_back(Rel);
368       // Set base offset for subsequent bitmap entries.
369       Base = Entry + sizeof(Addr);
370     } else {
371       // Odd entry: encodes bitmap for relocations starting at base.
372       for (Addr Offset = Base; (Entry >>= 1) != 0; Offset += sizeof(Addr))
373         if ((Entry & 1) != 0) {
374           Rel.r_offset = Offset;
375           Relocs.push_back(Rel);
376         }
377       Base += (CHAR_BIT * sizeof(Entry) - 1) * sizeof(Addr);
378     }
379   }
380 
381   return Relocs;
382 }
383 
384 template <class ELFT>
385 Expected<std::vector<typename ELFT::Rela>>
386 ELFFile<ELFT>::android_relas(const Elf_Shdr &Sec) const {
387   // This function reads relocations in Android's packed relocation format,
388   // which is based on SLEB128 and delta encoding.
389   Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
390   if (!ContentsOrErr)
391     return ContentsOrErr.takeError();
392   ArrayRef<uint8_t> Content = *ContentsOrErr;
393   if (Content.size() < 4 || Content[0] != 'A' || Content[1] != 'P' ||
394       Content[2] != 'S' || Content[3] != '2')
395     return createError("invalid packed relocation header");
396   DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4);
397   DataExtractor::Cursor Cur(/*Offset=*/4);
398 
399   uint64_t NumRelocs = Data.getSLEB128(Cur);
400   uint64_t Offset = Data.getSLEB128(Cur);
401   uint64_t Addend = 0;
402 
403   if (!Cur)
404     return std::move(Cur.takeError());
405 
406   std::vector<Elf_Rela> Relocs;
407   Relocs.reserve(NumRelocs);
408   while (NumRelocs) {
409     uint64_t NumRelocsInGroup = Data.getSLEB128(Cur);
410     if (!Cur)
411       return std::move(Cur.takeError());
412     if (NumRelocsInGroup > NumRelocs)
413       return createError("relocation group unexpectedly large");
414     NumRelocs -= NumRelocsInGroup;
415 
416     uint64_t GroupFlags = Data.getSLEB128(Cur);
417     bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG;
418     bool GroupedByOffsetDelta = GroupFlags & ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG;
419     bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG;
420     bool GroupHasAddend = GroupFlags & ELF::RELOCATION_GROUP_HAS_ADDEND_FLAG;
421 
422     uint64_t GroupOffsetDelta;
423     if (GroupedByOffsetDelta)
424       GroupOffsetDelta = Data.getSLEB128(Cur);
425 
426     uint64_t GroupRInfo;
427     if (GroupedByInfo)
428       GroupRInfo = Data.getSLEB128(Cur);
429 
430     if (GroupedByAddend && GroupHasAddend)
431       Addend += Data.getSLEB128(Cur);
432 
433     if (!GroupHasAddend)
434       Addend = 0;
435 
436     for (uint64_t I = 0; Cur && I != NumRelocsInGroup; ++I) {
437       Elf_Rela R;
438       Offset += GroupedByOffsetDelta ? GroupOffsetDelta : Data.getSLEB128(Cur);
439       R.r_offset = Offset;
440       R.r_info = GroupedByInfo ? GroupRInfo : Data.getSLEB128(Cur);
441       if (GroupHasAddend && !GroupedByAddend)
442         Addend += Data.getSLEB128(Cur);
443       R.r_addend = Addend;
444       Relocs.push_back(R);
445     }
446     if (!Cur)
447       return std::move(Cur.takeError());
448   }
449 
450   return Relocs;
451 }
452 
453 template <class ELFT>
454 std::string ELFFile<ELFT>::getDynamicTagAsString(unsigned Arch,
455                                                  uint64_t Type) const {
456 #define DYNAMIC_STRINGIFY_ENUM(tag, value)                                     \
457   case value:                                                                  \
458     return #tag;
459 
460 #define DYNAMIC_TAG(n, v)
461   switch (Arch) {
462   case ELF::EM_AARCH64:
463     switch (Type) {
464 #define AARCH64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
465 #include "llvm/BinaryFormat/DynamicTags.def"
466 #undef AARCH64_DYNAMIC_TAG
467     }
468     break;
469 
470   case ELF::EM_HEXAGON:
471     switch (Type) {
472 #define HEXAGON_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
473 #include "llvm/BinaryFormat/DynamicTags.def"
474 #undef HEXAGON_DYNAMIC_TAG
475     }
476     break;
477 
478   case ELF::EM_MIPS:
479     switch (Type) {
480 #define MIPS_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
481 #include "llvm/BinaryFormat/DynamicTags.def"
482 #undef MIPS_DYNAMIC_TAG
483     }
484     break;
485 
486   case ELF::EM_PPC:
487     switch (Type) {
488 #define PPC_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
489 #include "llvm/BinaryFormat/DynamicTags.def"
490 #undef PPC_DYNAMIC_TAG
491     }
492     break;
493 
494   case ELF::EM_PPC64:
495     switch (Type) {
496 #define PPC64_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
497 #include "llvm/BinaryFormat/DynamicTags.def"
498 #undef PPC64_DYNAMIC_TAG
499     }
500     break;
501 
502   case ELF::EM_RISCV:
503     switch (Type) {
504 #define RISCV_DYNAMIC_TAG(name, value) DYNAMIC_STRINGIFY_ENUM(name, value)
505 #include "llvm/BinaryFormat/DynamicTags.def"
506 #undef RISCV_DYNAMIC_TAG
507     }
508     break;
509   }
510 #undef DYNAMIC_TAG
511   switch (Type) {
512 // Now handle all dynamic tags except the architecture specific ones
513 #define AARCH64_DYNAMIC_TAG(name, value)
514 #define MIPS_DYNAMIC_TAG(name, value)
515 #define HEXAGON_DYNAMIC_TAG(name, value)
516 #define PPC_DYNAMIC_TAG(name, value)
517 #define PPC64_DYNAMIC_TAG(name, value)
518 #define RISCV_DYNAMIC_TAG(name, value)
519 // Also ignore marker tags such as DT_HIOS (maps to DT_VERNEEDNUM), etc.
520 #define DYNAMIC_TAG_MARKER(name, value)
521 #define DYNAMIC_TAG(name, value) case value: return #name;
522 #include "llvm/BinaryFormat/DynamicTags.def"
523 #undef DYNAMIC_TAG
524 #undef AARCH64_DYNAMIC_TAG
525 #undef MIPS_DYNAMIC_TAG
526 #undef HEXAGON_DYNAMIC_TAG
527 #undef PPC_DYNAMIC_TAG
528 #undef PPC64_DYNAMIC_TAG
529 #undef RISCV_DYNAMIC_TAG
530 #undef DYNAMIC_TAG_MARKER
531 #undef DYNAMIC_STRINGIFY_ENUM
532   default:
533     return "<unknown:>0x" + utohexstr(Type, true);
534   }
535 }
536 
537 template <class ELFT>
538 std::string ELFFile<ELFT>::getDynamicTagAsString(uint64_t Type) const {
539   return getDynamicTagAsString(getHeader().e_machine, Type);
540 }
541 
542 template <class ELFT>
543 Expected<typename ELFT::DynRange> ELFFile<ELFT>::dynamicEntries() const {
544   ArrayRef<Elf_Dyn> Dyn;
545 
546   auto ProgramHeadersOrError = program_headers();
547   if (!ProgramHeadersOrError)
548     return ProgramHeadersOrError.takeError();
549 
550   for (const Elf_Phdr &Phdr : *ProgramHeadersOrError) {
551     if (Phdr.p_type == ELF::PT_DYNAMIC) {
552       Dyn = ArrayRef(reinterpret_cast<const Elf_Dyn *>(base() + Phdr.p_offset),
553                      Phdr.p_filesz / sizeof(Elf_Dyn));
554       break;
555     }
556   }
557 
558   // If we can't find the dynamic section in the program headers, we just fall
559   // back on the sections.
560   if (Dyn.empty()) {
561     auto SectionsOrError = sections();
562     if (!SectionsOrError)
563       return SectionsOrError.takeError();
564 
565     for (const Elf_Shdr &Sec : *SectionsOrError) {
566       if (Sec.sh_type == ELF::SHT_DYNAMIC) {
567         Expected<ArrayRef<Elf_Dyn>> DynOrError =
568             getSectionContentsAsArray<Elf_Dyn>(Sec);
569         if (!DynOrError)
570           return DynOrError.takeError();
571         Dyn = *DynOrError;
572         break;
573       }
574     }
575 
576     if (!Dyn.data())
577       return ArrayRef<Elf_Dyn>();
578   }
579 
580   if (Dyn.empty())
581     return createError("invalid empty dynamic section");
582 
583   if (Dyn.back().d_tag != ELF::DT_NULL)
584     return createError("dynamic sections must be DT_NULL terminated");
585 
586   return Dyn;
587 }
588 
589 template <class ELFT>
590 Expected<const uint8_t *>
591 ELFFile<ELFT>::toMappedAddr(uint64_t VAddr, WarningHandler WarnHandler) const {
592   auto ProgramHeadersOrError = program_headers();
593   if (!ProgramHeadersOrError)
594     return ProgramHeadersOrError.takeError();
595 
596   llvm::SmallVector<Elf_Phdr *, 4> LoadSegments;
597 
598   for (const Elf_Phdr &Phdr : *ProgramHeadersOrError)
599     if (Phdr.p_type == ELF::PT_LOAD)
600       LoadSegments.push_back(const_cast<Elf_Phdr *>(&Phdr));
601 
602   auto SortPred = [](const Elf_Phdr_Impl<ELFT> *A,
603                      const Elf_Phdr_Impl<ELFT> *B) {
604     return A->p_vaddr < B->p_vaddr;
605   };
606   if (!llvm::is_sorted(LoadSegments, SortPred)) {
607     if (Error E =
608             WarnHandler("loadable segments are unsorted by virtual address"))
609       return std::move(E);
610     llvm::stable_sort(LoadSegments, SortPred);
611   }
612 
613   const Elf_Phdr *const *I = llvm::upper_bound(
614       LoadSegments, VAddr, [](uint64_t VAddr, const Elf_Phdr_Impl<ELFT> *Phdr) {
615         return VAddr < Phdr->p_vaddr;
616       });
617 
618   if (I == LoadSegments.begin())
619     return createError("virtual address is not in any segment: 0x" +
620                        Twine::utohexstr(VAddr));
621   --I;
622   const Elf_Phdr &Phdr = **I;
623   uint64_t Delta = VAddr - Phdr.p_vaddr;
624   if (Delta >= Phdr.p_filesz)
625     return createError("virtual address is not in any segment: 0x" +
626                        Twine::utohexstr(VAddr));
627 
628   uint64_t Offset = Phdr.p_offset + Delta;
629   if (Offset >= getBufSize())
630     return createError("can't map virtual address 0x" +
631                        Twine::utohexstr(VAddr) + " to the segment with index " +
632                        Twine(&Phdr - (*ProgramHeadersOrError).data() + 1) +
633                        ": the segment ends at 0x" +
634                        Twine::utohexstr(Phdr.p_offset + Phdr.p_filesz) +
635                        ", which is greater than the file size (0x" +
636                        Twine::utohexstr(getBufSize()) + ")");
637 
638   return base() + Offset;
639 }
640 
641 template <class ELFT>
642 Expected<std::vector<BBAddrMap>>
643 ELFFile<ELFT>::decodeBBAddrMap(const Elf_Shdr &Sec) const {
644   Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
645   if (!ContentsOrErr)
646     return ContentsOrErr.takeError();
647   ArrayRef<uint8_t> Content = *ContentsOrErr;
648   DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4);
649   std::vector<BBAddrMap> FunctionEntries;
650 
651   DataExtractor::Cursor Cur(0);
652   Error ULEBSizeErr = Error::success();
653   // Helper to extract and decode the next ULEB128 value as uint32_t.
654   // Returns zero and sets ULEBSizeErr if the ULEB128 value exceeds the uint32_t
655   // limit.
656   // Also returns zero if ULEBSizeErr is already in an error state.
657   auto ReadULEB128AsUInt32 = [&Data, &Cur, &ULEBSizeErr]() -> uint32_t {
658     // Bail out and do not extract data if ULEBSizeErr is already set.
659     if (ULEBSizeErr)
660       return 0;
661     uint64_t Offset = Cur.tell();
662     uint64_t Value = Data.getULEB128(Cur);
663     if (Value > UINT32_MAX) {
664       ULEBSizeErr = createError(
665           "ULEB128 value at offset 0x" + Twine::utohexstr(Offset) +
666           " exceeds UINT32_MAX (0x" + Twine::utohexstr(Value) + ")");
667       return 0;
668     }
669     return static_cast<uint32_t>(Value);
670   };
671 
672   uint8_t Version = 0;
673   while (!ULEBSizeErr && Cur && Cur.tell() < Content.size()) {
674     if (Sec.sh_type == ELF::SHT_LLVM_BB_ADDR_MAP) {
675       Version = Data.getU8(Cur);
676       if (!Cur)
677         break;
678       if (Version > 2)
679         return createError("unsupported SHT_LLVM_BB_ADDR_MAP version: " +
680                            Twine(static_cast<int>(Version)));
681       Data.getU8(Cur); // Feature byte
682     }
683     uintX_t Address = static_cast<uintX_t>(Data.getAddress(Cur));
684     uint32_t NumBlocks = ReadULEB128AsUInt32();
685     std::vector<BBAddrMap::BBEntry> BBEntries;
686     uint32_t PrevBBEndOffset = 0;
687     for (uint32_t BlockIndex = 0;
688          !ULEBSizeErr && Cur && (BlockIndex < NumBlocks); ++BlockIndex) {
689       uint32_t ID = Version >= 2 ? ReadULEB128AsUInt32() : BlockIndex;
690       uint32_t Offset = ReadULEB128AsUInt32();
691       uint32_t Size = ReadULEB128AsUInt32();
692       uint32_t Metadata = ReadULEB128AsUInt32();
693       if (Version >= 1) {
694         // Offset is calculated relative to the end of the previous BB.
695         Offset += PrevBBEndOffset;
696         PrevBBEndOffset = Offset + Size;
697       }
698       BBEntries.push_back({ID, Offset, Size, Metadata});
699     }
700     FunctionEntries.push_back({Address, std::move(BBEntries)});
701   }
702   // Either Cur is in the error state, or ULEBSizeError is set (not both), but
703   // we join the two errors here to be safe.
704   if (!Cur || ULEBSizeErr)
705     return joinErrors(Cur.takeError(), std::move(ULEBSizeErr));
706   return FunctionEntries;
707 }
708 
709 template class llvm::object::ELFFile<ELF32LE>;
710 template class llvm::object::ELFFile<ELF32BE>;
711 template class llvm::object::ELFFile<ELF64LE>;
712 template class llvm::object::ELFFile<ELF64BE>;
713