1 //===-- ELFDump.cpp - ELF-specific dumper -----------------------*- C++ -*-===//
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 /// \file
11 /// This file implements the ELF-specific dumper for llvm-objdump.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm-objdump.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;
22 using namespace llvm::object;
23 
24 template <class ELFT>
25 Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> *Elf) {
26   typedef ELFFile<ELFT> ELFO;
27 
28   auto DynamicEntriesOrError = Elf->dynamicEntries();
29   if (!DynamicEntriesOrError)
30     return DynamicEntriesOrError.takeError();
31 
32   for (const typename ELFO::Elf_Dyn &Dyn : *DynamicEntriesOrError) {
33     if (Dyn.d_tag == ELF::DT_STRTAB) {
34       auto MappedAddrOrError = Elf->toMappedAddr(Dyn.getPtr());
35       if (!MappedAddrOrError)
36         consumeError(MappedAddrOrError.takeError());
37       return StringRef(reinterpret_cast<const char *>(*MappedAddrOrError));
38     }
39   }
40 
41   // If the dynamic segment is not present, we fall back on the sections.
42   auto SectionsOrError = Elf->sections();
43   if (!SectionsOrError)
44     return SectionsOrError.takeError();
45 
46   for (const typename ELFO::Elf_Shdr &Sec : *SectionsOrError) {
47     if (Sec.sh_type == ELF::SHT_DYNSYM)
48       return Elf->getStringTableForSymtab(Sec);
49   }
50 
51   return createError("dynamic string table not found");
52 }
53 
54 template <class ELFT>
55 void printDynamicSection(const ELFFile<ELFT> *Elf, StringRef Filename) {
56   auto ProgramHeaderOrError = Elf->program_headers();
57   if (!ProgramHeaderOrError)
58     report_error(Filename, ProgramHeaderOrError.takeError());
59 
60   auto DynamicEntriesOrError = Elf->dynamicEntries();
61   if (!DynamicEntriesOrError)
62     report_error(Filename, DynamicEntriesOrError.takeError());
63 
64   outs() << "Dynamic Section:\n";
65   for (const auto &Dyn : *DynamicEntriesOrError) {
66     if (Dyn.d_tag == ELF::DT_NULL)
67       continue;
68 
69     StringRef Str = StringRef(Elf->getDynamicTagAsString(Dyn.d_tag));
70 
71     if (Str.empty()) {
72       std::string HexStr = utohexstr(static_cast<uint64_t>(Dyn.d_tag), true);
73       outs() << format("  0x%-19s", HexStr.c_str());
74     } else {
75       // We use "-21" in order to match GNU objdump's output.
76       outs() << format("  %-21s", Str.data());
77     }
78 
79     const char *Fmt =
80         ELFT::Is64Bits ? "0x%016" PRIx64 "\n" : "0x%08" PRIx64 "\n";
81     if (Dyn.d_tag == ELF::DT_NEEDED) {
82       Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf);
83       if (StrTabOrErr) {
84         const char *Data = StrTabOrErr.get().data();
85         outs() << (Data + Dyn.d_un.d_val) << "\n";
86         continue;
87       }
88       warn(errorToErrorCode(StrTabOrErr.takeError()).message());
89       consumeError(StrTabOrErr.takeError());
90     }
91     outs() << format(Fmt, (uint64_t)Dyn.d_un.d_val);
92   }
93 }
94 
95 template <class ELFT> void printProgramHeaders(const ELFFile<ELFT> *o) {
96   typedef ELFFile<ELFT> ELFO;
97   outs() << "Program Header:\n";
98   auto ProgramHeaderOrError = o->program_headers();
99   if (!ProgramHeaderOrError)
100     report_fatal_error(
101         errorToErrorCode(ProgramHeaderOrError.takeError()).message());
102   for (const typename ELFO::Elf_Phdr &Phdr : *ProgramHeaderOrError) {
103     switch (Phdr.p_type) {
104     case ELF::PT_DYNAMIC:
105       outs() << " DYNAMIC ";
106       break;
107     case ELF::PT_GNU_EH_FRAME:
108       outs() << "EH_FRAME ";
109       break;
110     case ELF::PT_GNU_RELRO:
111       outs() << "   RELRO ";
112       break;
113     case ELF::PT_GNU_STACK:
114       outs() << "   STACK ";
115       break;
116     case ELF::PT_INTERP:
117       outs() << "  INTERP ";
118       break;
119     case ELF::PT_LOAD:
120       outs() << "    LOAD ";
121       break;
122     case ELF::PT_NOTE:
123       outs() << "    NOTE ";
124       break;
125     case ELF::PT_OPENBSD_BOOTDATA:
126       outs() << "    OPENBSD_BOOTDATA ";
127       break;
128     case ELF::PT_OPENBSD_RANDOMIZE:
129       outs() << "    OPENBSD_RANDOMIZE ";
130       break;
131     case ELF::PT_OPENBSD_WXNEEDED:
132       outs() << "    OPENBSD_WXNEEDED ";
133       break;
134     case ELF::PT_PHDR:
135       outs() << "    PHDR ";
136       break;
137     case ELF::PT_TLS:
138       outs() << "    TLS ";
139       break;
140     default:
141       outs() << " UNKNOWN ";
142     }
143 
144     const char *Fmt = ELFT::Is64Bits ? "0x%016" PRIx64 " " : "0x%08" PRIx64 " ";
145 
146     outs() << "off    " << format(Fmt, (uint64_t)Phdr.p_offset) << "vaddr "
147            << format(Fmt, (uint64_t)Phdr.p_vaddr) << "paddr "
148            << format(Fmt, (uint64_t)Phdr.p_paddr)
149            << format("align 2**%u\n",
150                      countTrailingZeros<uint64_t>(Phdr.p_align))
151            << "         filesz " << format(Fmt, (uint64_t)Phdr.p_filesz)
152            << "memsz " << format(Fmt, (uint64_t)Phdr.p_memsz) << "flags "
153            << ((Phdr.p_flags & ELF::PF_R) ? "r" : "-")
154            << ((Phdr.p_flags & ELF::PF_W) ? "w" : "-")
155            << ((Phdr.p_flags & ELF::PF_X) ? "x" : "-") << "\n";
156   }
157   outs() << "\n";
158 }
159 
160 void llvm::printELFFileHeader(const object::ObjectFile *Obj) {
161   if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
162     printProgramHeaders(ELFObj->getELFFile());
163   else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
164     printProgramHeaders(ELFObj->getELFFile());
165   else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
166     printProgramHeaders(ELFObj->getELFFile());
167   else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
168     printProgramHeaders(ELFObj->getELFFile());
169 }
170 
171 void llvm::printELFDynamicSection(const object::ObjectFile *Obj) {
172   if (const auto *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
173     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
174   else if (const auto *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
175     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
176   else if (const auto *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
177     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
178   else if (const auto *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
179     printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
180 }
181