xref: /freebsd/contrib/llvm-project/llvm/tools/llvm-objdump/ELFDump.cpp (revision 2f513db72b034fd5ef7f080b11be5c711c15186a) 
1 //===-- ELFDump.cpp - ELF-specific dumper -----------------------*- C++ -*-===//
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 /// \file
10 /// This file implements the ELF-specific dumper for llvm-objdump.
11 ///
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm-objdump.h"
15 #include "llvm/Demangle/Demangle.h"
16 #include "llvm/Object/ELFObjectFile.h"
17 #include "llvm/Support/Format.h"
18 #include "llvm/Support/MathExtras.h"
19 #include "llvm/Support/raw_ostream.h"
20 
21 using namespace llvm::object;
22 
23 namespace llvm {
24 template <class ELFT>
25 static Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> *Elf) {
26   auto DynamicEntriesOrError = Elf->dynamicEntries();
27   if (!DynamicEntriesOrError)
28     return DynamicEntriesOrError.takeError();
29 
30   for (const typename ELFT::Dyn &Dyn : *DynamicEntriesOrError) {
31     if (Dyn.d_tag == ELF::DT_STRTAB) {
32       auto MappedAddrOrError = Elf->toMappedAddr(Dyn.getPtr());
33       if (!MappedAddrOrError)
34         consumeError(MappedAddrOrError.takeError());
35       return StringRef(reinterpret_cast<const char *>(*MappedAddrOrError));
36     }
37   }
38 
39   // If the dynamic segment is not present, we fall back on the sections.
40   auto SectionsOrError = Elf->sections();
41   if (!SectionsOrError)
42     return SectionsOrError.takeError();
43 
44   for (const typename ELFT::Shdr &Sec : *SectionsOrError) {
45     if (Sec.sh_type == ELF::SHT_DYNSYM)
46       return Elf->getStringTableForSymtab(Sec);
47   }
48 
49   return createError("dynamic string table not found");
50 }
51 
52 template <class ELFT>
53 static Error getRelocationValueString(const ELFObjectFile<ELFT> *Obj,
54                                       const RelocationRef &RelRef,
55                                       SmallVectorImpl<char> &Result) {
56   const ELFFile<ELFT> &EF = *Obj->getELFFile();
57   DataRefImpl Rel = RelRef.getRawDataRefImpl();
58   auto SecOrErr = EF.getSection(Rel.d.a);
59   if (!SecOrErr)
60     return SecOrErr.takeError();
61 
62   int64_t Addend = 0;
63   // If there is no Symbol associated with the relocation, we set the undef
64   // boolean value to 'true'. This will prevent us from calling functions that
65   // requires the relocation to be associated with a symbol.
66   //
67   // In SHT_REL case we would need to read the addend from section data.
68   // GNU objdump does not do that and we just follow for simplicity atm.
69   bool Undef = false;
70   if ((*SecOrErr)->sh_type == ELF::SHT_RELA) {
71     const typename ELFT::Rela *ERela = Obj->getRela(Rel);
72     Addend = ERela->r_addend;
73     Undef = ERela->getSymbol(false) == 0;
74   } else if ((*SecOrErr)->sh_type != ELF::SHT_REL) {
75     return make_error<BinaryError>();
76   }
77 
78   // Default scheme is to print Target, as well as "+ <addend>" for nonzero
79   // addend. Should be acceptable for all normal purposes.
80   std::string FmtBuf;
81   raw_string_ostream Fmt(FmtBuf);
82 
83   if (!Undef) {
84     symbol_iterator SI = RelRef.getSymbol();
85     const typename ELFT::Sym *Sym = Obj->getSymbol(SI->getRawDataRefImpl());
86     if (Sym->getType() == ELF::STT_SECTION) {
87       Expected<section_iterator> SymSI = SI->getSection();
88       if (!SymSI)
89         return SymSI.takeError();
90       const typename ELFT::Shdr *SymSec =
91           Obj->getSection((*SymSI)->getRawDataRefImpl());
92       auto SecName = EF.getSectionName(SymSec);
93       if (!SecName)
94         return SecName.takeError();
95       Fmt << *SecName;
96     } else {
97       Expected<StringRef> SymName = SI->getName();
98       if (!SymName)
99         return SymName.takeError();
100       if (Demangle)
101         Fmt << demangle(*SymName);
102       else
103         Fmt << *SymName;
104     }
105   } else {
106     Fmt << "*ABS*";
107   }
108 
109   if (Addend != 0)
110     Fmt << (Addend < 0 ? "" : "+") << Addend;
111   Fmt.flush();
112   Result.append(FmtBuf.begin(), FmtBuf.end());
113   return Error::success();
114 }
115 
116 Error getELFRelocationValueString(const ELFObjectFileBase *Obj,
117                                   const RelocationRef &Rel,
118                                   SmallVectorImpl<char> &Result) {
119   if (auto *ELF32LE = dyn_cast<ELF32LEObjectFile>(Obj))
120     return getRelocationValueString(ELF32LE, Rel, Result);
121   if (auto *ELF64LE = dyn_cast<ELF64LEObjectFile>(Obj))
122     return getRelocationValueString(ELF64LE, Rel, Result);
123   if (auto *ELF32BE = dyn_cast<ELF32BEObjectFile>(Obj))
124     return getRelocationValueString(ELF32BE, Rel, Result);
125   auto *ELF64BE = cast<ELF64BEObjectFile>(Obj);
126   return getRelocationValueString(ELF64BE, Rel, Result);
127 }
128 
129 template <class ELFT>
130 static uint64_t getSectionLMA(const ELFFile<ELFT> *Obj,
131                               const object::ELFSectionRef &Sec) {
132   auto PhdrRangeOrErr = Obj->program_headers();
133   if (!PhdrRangeOrErr)
134     report_fatal_error(toString(PhdrRangeOrErr.takeError()));
135 
136   // Search for a PT_LOAD segment containing the requested section. Use this
137   // segment's p_addr to calculate the section's LMA.
138   for (const typename ELFT::Phdr &Phdr : *PhdrRangeOrErr)
139     if ((Phdr.p_type == ELF::PT_LOAD) && (Phdr.p_vaddr <= Sec.getAddress()) &&
140         (Phdr.p_vaddr + Phdr.p_memsz > Sec.getAddress()))
141       return Sec.getAddress() - Phdr.p_vaddr + Phdr.p_paddr;
142 
143   // Return section's VMA if it isn't in a PT_LOAD segment.
144   return Sec.getAddress();
145 }
146 
147 uint64_t getELFSectionLMA(const object::ELFSectionRef &Sec) {
148   if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Sec.getObject()))
149     return getSectionLMA(ELFObj->getELFFile(), Sec);
150   else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Sec.getObject()))
151     return getSectionLMA(ELFObj->getELFFile(), Sec);
152   else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Sec.getObject()))
153     return getSectionLMA(ELFObj->getELFFile(), Sec);
154   const auto *ELFObj = cast<ELF64BEObjectFile>(Sec.getObject());
155   return getSectionLMA(ELFObj->getELFFile(), Sec);
156 }
157 
158 template <class ELFT>
159 void printDynamicSection(const ELFFile<ELFT> *Elf, StringRef Filename) {
160   ArrayRef<typename ELFT::Dyn> DynamicEntries =
161       unwrapOrError(Elf->dynamicEntries(), Filename);
162   outs() << "Dynamic Section:\n";
163   for (const typename ELFT::Dyn &Dyn : DynamicEntries) {
164     if (Dyn.d_tag == ELF::DT_NULL)
165       continue;
166 
167     std::string Str = Elf->getDynamicTagAsString(Dyn.d_tag);
168     outs() << format("  %-21s", Str.c_str());
169 
170     const char *Fmt =
171         ELFT::Is64Bits ? "0x%016" PRIx64 "\n" : "0x%08" PRIx64 "\n";
172     if (Dyn.d_tag == ELF::DT_NEEDED || Dyn.d_tag == ELF::DT_RPATH ||
173         Dyn.d_tag == ELF::DT_RUNPATH || Dyn.d_tag == ELF::DT_SONAME ||
174         Dyn.d_tag == ELF::DT_AUXILIARY || Dyn.d_tag == ELF::DT_FILTER) {
175       Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf);
176       if (StrTabOrErr) {
177         const char *Data = StrTabOrErr.get().data();
178         outs() << (Data + Dyn.d_un.d_val) << "\n";
179         continue;
180       }
181       warn(toString(StrTabOrErr.takeError()));
182       consumeError(StrTabOrErr.takeError());
183     }
184     outs() << format(Fmt, (uint64_t)Dyn.d_un.d_val);
185   }
186 }
187 
188 template <class ELFT> void printProgramHeaders(const ELFFile<ELFT> *o) {
189   outs() << "Program Header:\n";
190   auto ProgramHeaderOrError = o->program_headers();
191   if (!ProgramHeaderOrError)
192     report_fatal_error(toString(ProgramHeaderOrError.takeError()));
193   for (const typename ELFT::Phdr &Phdr : *ProgramHeaderOrError) {
194     switch (Phdr.p_type) {
195     case ELF::PT_DYNAMIC:
196       outs() << " DYNAMIC ";
197       break;
198     case ELF::PT_GNU_EH_FRAME:
199       outs() << "EH_FRAME ";
200       break;
201     case ELF::PT_GNU_RELRO:
202       outs() << "   RELRO ";
203       break;
204     case ELF::PT_GNU_STACK:
205       outs() << "   STACK ";
206       break;
207     case ELF::PT_INTERP:
208       outs() << "  INTERP ";
209       break;
210     case ELF::PT_LOAD:
211       outs() << "    LOAD ";
212       break;
213     case ELF::PT_NOTE:
214       outs() << "    NOTE ";
215       break;
216     case ELF::PT_OPENBSD_BOOTDATA:
217       outs() << "    OPENBSD_BOOTDATA ";
218       break;
219     case ELF::PT_OPENBSD_RANDOMIZE:
220       outs() << "    OPENBSD_RANDOMIZE ";
221       break;
222     case ELF::PT_OPENBSD_WXNEEDED:
223       outs() << "    OPENBSD_WXNEEDED ";
224       break;
225     case ELF::PT_PHDR:
226       outs() << "    PHDR ";
227       break;
228     case ELF::PT_TLS:
229       outs() << "    TLS ";
230       break;
231     default:
232       outs() << " UNKNOWN ";
233     }
234 
235     const char *Fmt = ELFT::Is64Bits ? "0x%016" PRIx64 " " : "0x%08" PRIx64 " ";
236 
237     outs() << "off    " << format(Fmt, (uint64_t)Phdr.p_offset) << "vaddr "
238            << format(Fmt, (uint64_t)Phdr.p_vaddr) << "paddr "
239            << format(Fmt, (uint64_t)Phdr.p_paddr)
240            << format("align 2**%u\n",
241                      countTrailingZeros<uint64_t>(Phdr.p_align))
242            << "         filesz " << format(Fmt, (uint64_t)Phdr.p_filesz)
243            << "memsz " << format(Fmt, (uint64_t)Phdr.p_memsz) << "flags "
244            << ((Phdr.p_flags & ELF::PF_R) ? "r" : "-")
245            << ((Phdr.p_flags & ELF::PF_W) ? "w" : "-")
246            << ((Phdr.p_flags & ELF::PF_X) ? "x" : "-") << "\n";
247   }
248   outs() << "\n";
249 }
250 
251 template <class ELFT>
252 void printSymbolVersionDependency(ArrayRef<uint8_t> Contents,
253                                   StringRef StrTab) {
254   outs() << "Version References:\n";
255 
256   const uint8_t *Buf = Contents.data();
257   while (Buf) {
258     auto *Verneed = reinterpret_cast<const typename ELFT::Verneed *>(Buf);
259     outs() << "  required from "
260            << StringRef(StrTab.drop_front(Verneed->vn_file).data()) << ":\n";
261 
262     const uint8_t *BufAux = Buf + Verneed->vn_aux;
263     while (BufAux) {
264       auto *Vernaux = reinterpret_cast<const typename ELFT::Vernaux *>(BufAux);
265       outs() << "    "
266              << format("0x%08" PRIx32 " ", (uint32_t)Vernaux->vna_hash)
267              << format("0x%02" PRIx16 " ", (uint16_t)Vernaux->vna_flags)
268              << format("%02" PRIu16 " ", (uint16_t)Vernaux->vna_other)
269              << StringRef(StrTab.drop_front(Vernaux->vna_name).data()) << '\n';
270       BufAux = Vernaux->vna_next ? BufAux + Vernaux->vna_next : nullptr;
271     }
272     Buf = Verneed->vn_next ? Buf + Verneed->vn_next : nullptr;
273   }
274 }
275 
276 template <class ELFT>
277 void printSymbolVersionDefinition(const typename ELFT::Shdr &Shdr,
278                                   ArrayRef<uint8_t> Contents,
279                                   StringRef StrTab) {
280   outs() << "Version definitions:\n";
281 
282   const uint8_t *Buf = Contents.data();
283   uint32_t VerdefIndex = 1;
284   // sh_info contains the number of entries in the SHT_GNU_verdef section. To
285   // make the index column have consistent width, we should insert blank spaces
286   // according to sh_info.
287   uint16_t VerdefIndexWidth = std::to_string(Shdr.sh_info).size();
288   while (Buf) {
289     auto *Verdef = reinterpret_cast<const typename ELFT::Verdef *>(Buf);
290     outs() << format_decimal(VerdefIndex++, VerdefIndexWidth) << " "
291            << format("0x%02" PRIx16 " ", (uint16_t)Verdef->vd_flags)
292            << format("0x%08" PRIx32 " ", (uint32_t)Verdef->vd_hash);
293 
294     const uint8_t *BufAux = Buf + Verdef->vd_aux;
295     uint16_t VerdauxIndex = 0;
296     while (BufAux) {
297       auto *Verdaux = reinterpret_cast<const typename ELFT::Verdaux *>(BufAux);
298       if (VerdauxIndex)
299         outs() << std::string(VerdefIndexWidth + 17, ' ');
300       outs() << StringRef(StrTab.drop_front(Verdaux->vda_name).data()) << '\n';
301       BufAux = Verdaux->vda_next ? BufAux + Verdaux->vda_next : nullptr;
302       ++VerdauxIndex;
303     }
304     Buf = Verdef->vd_next ? Buf + Verdef->vd_next : nullptr;
305   }
306 }
307 
308 template <class ELFT>
309 void printSymbolVersionInfo(const ELFFile<ELFT> *Elf, StringRef FileName) {
310   ArrayRef<typename ELFT::Shdr> Sections =
311       unwrapOrError(Elf->sections(), FileName);
312   for (const typename ELFT::Shdr &Shdr : Sections) {
313     if (Shdr.sh_type != ELF::SHT_GNU_verneed &&
314         Shdr.sh_type != ELF::SHT_GNU_verdef)
315       continue;
316 
317     ArrayRef<uint8_t> Contents =
318         unwrapOrError(Elf->getSectionContents(&Shdr), FileName);
319     const typename ELFT::Shdr *StrTabSec =
320         unwrapOrError(Elf->getSection(Shdr.sh_link), FileName);
321     StringRef StrTab = unwrapOrError(Elf->getStringTable(StrTabSec), FileName);
322 
323     if (Shdr.sh_type == ELF::SHT_GNU_verneed)
324       printSymbolVersionDependency<ELFT>(Contents, StrTab);
325     else
326       printSymbolVersionDefinition<ELFT>(Shdr, Contents, StrTab);
327   }
328 }
329 
330 void printELFFileHeader(const object::ObjectFile *Obj) {
331   if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
332     printProgramHeaders(ELFObj->getELFFile());
333   else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
334     printProgramHeaders(ELFObj->getELFFile());
335   else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
336     printProgramHeaders(ELFObj->getELFFile());
337   else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
338     printProgramHeaders(ELFObj->getELFFile());
339 }
340 
341 void printELFDynamicSection(const object::ObjectFile *Obj) {
342   if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
343     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
344   else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
345     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
346   else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
347     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
348   else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
349     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
350 }
351 
352 void printELFSymbolVersionInfo(const object::ObjectFile *Obj) {
353   if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
354     printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
355   else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
356     printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
357   else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
358     printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
359   else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
360     printSymbolVersionInfo(ELFObj->getELFFile(), Obj->getFileName());
361 }
362 } // namespace llvm
363