1 //===-- ObjectFileELF.h --------------------------------------- -*- 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 #ifndef liblldb_ObjectFileELF_h_
10 #define liblldb_ObjectFileELF_h_
11 
12 #include <stdint.h>
13 
14 #include <vector>
15 
16 #include "lldb/Symbol/ObjectFile.h"
17 #include "lldb/Utility/ArchSpec.h"
18 #include "lldb/Utility/FileSpec.h"
19 #include "lldb/Utility/UUID.h"
20 #include "lldb/lldb-private.h"
21 
22 #include "ELFHeader.h"
23 
24 struct ELFNote {
25   elf::elf_word n_namesz;
26   elf::elf_word n_descsz;
27   elf::elf_word n_type;
28 
29   std::string n_name;
30 
31   ELFNote() : n_namesz(0), n_descsz(0), n_type(0) {}
32 
33   /// Parse an ELFNote entry from the given DataExtractor starting at position
34   /// \p offset.
35   ///
36   /// \param[in] data
37   ///    The DataExtractor to read from.
38   ///
39   /// \param[in,out] offset
40   ///    Pointer to an offset in the data.  On return the offset will be
41   ///    advanced by the number of bytes read.
42   ///
43   /// \return
44   ///    True if the ELFRel entry was successfully read and false otherwise.
45   bool Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset);
46 
47   size_t GetByteSize() const {
48     return 12 + llvm::alignTo(n_namesz, 4) + llvm::alignTo(n_descsz, 4);
49   }
50 };
51 
52 /// \class ObjectFileELF
53 /// Generic ELF object file reader.
54 ///
55 /// This class provides a generic ELF (32/64 bit) reader plugin implementing
56 /// the ObjectFile protocol.
57 class ObjectFileELF : public lldb_private::ObjectFile {
58 public:
59   // Static Functions
60   static void Initialize();
61 
62   static void Terminate();
63 
64   static lldb_private::ConstString GetPluginNameStatic();
65 
66   static const char *GetPluginDescriptionStatic();
67 
68   static lldb_private::ObjectFile *
69   CreateInstance(const lldb::ModuleSP &module_sp, lldb::DataBufferSP &data_sp,
70                  lldb::offset_t data_offset, const lldb_private::FileSpec *file,
71                  lldb::offset_t file_offset, lldb::offset_t length);
72 
73   static lldb_private::ObjectFile *CreateMemoryInstance(
74       const lldb::ModuleSP &module_sp, lldb::DataBufferSP &data_sp,
75       const lldb::ProcessSP &process_sp, lldb::addr_t header_addr);
76 
77   static size_t GetModuleSpecifications(const lldb_private::FileSpec &file,
78                                         lldb::DataBufferSP &data_sp,
79                                         lldb::offset_t data_offset,
80                                         lldb::offset_t file_offset,
81                                         lldb::offset_t length,
82                                         lldb_private::ModuleSpecList &specs);
83 
84   static bool MagicBytesMatch(lldb::DataBufferSP &data_sp, lldb::addr_t offset,
85                               lldb::addr_t length);
86 
87   // PluginInterface protocol
88   lldb_private::ConstString GetPluginName() override;
89 
90   uint32_t GetPluginVersion() override;
91 
92   // LLVM RTTI support
93   static char ID;
94   bool isA(const void *ClassID) const override {
95     return ClassID == &ID || ObjectFile::isA(ClassID);
96   }
97   static bool classof(const ObjectFile *obj) { return obj->isA(&ID); }
98 
99   // ObjectFile Protocol.
100   bool ParseHeader() override;
101 
102   bool SetLoadAddress(lldb_private::Target &target, lldb::addr_t value,
103                       bool value_is_offset) override;
104 
105   lldb::ByteOrder GetByteOrder() const override;
106 
107   bool IsExecutable() const override;
108 
109   uint32_t GetAddressByteSize() const override;
110 
111   lldb_private::AddressClass GetAddressClass(lldb::addr_t file_addr) override;
112 
113   lldb_private::Symtab *GetSymtab() override;
114 
115   bool IsStripped() override;
116 
117   void CreateSections(lldb_private::SectionList &unified_section_list) override;
118 
119   void Dump(lldb_private::Stream *s) override;
120 
121   lldb_private::ArchSpec GetArchitecture() override;
122 
123   lldb_private::UUID GetUUID() override;
124 
125   lldb_private::FileSpecList GetDebugSymbolFilePaths() override;
126 
127   uint32_t GetDependentModules(lldb_private::FileSpecList &files) override;
128 
129   lldb_private::Address
130   GetImageInfoAddress(lldb_private::Target *target) override;
131 
132   lldb_private::Address GetEntryPointAddress() override;
133 
134   lldb_private::Address GetBaseAddress() override;
135 
136   ObjectFile::Type CalculateType() override;
137 
138   ObjectFile::Strata CalculateStrata() override;
139 
140   size_t ReadSectionData(lldb_private::Section *section,
141                          lldb::offset_t section_offset, void *dst,
142                          size_t dst_len) override;
143 
144   size_t ReadSectionData(lldb_private::Section *section,
145                          lldb_private::DataExtractor &section_data) override;
146 
147   llvm::ArrayRef<elf::ELFProgramHeader> ProgramHeaders();
148   lldb_private::DataExtractor GetSegmentData(const elf::ELFProgramHeader &H);
149 
150   llvm::StringRef
151   StripLinkerSymbolAnnotations(llvm::StringRef symbol_name) const override;
152 
153   void RelocateSection(lldb_private::Section *section) override;
154 
155 protected:
156 
157   std::vector<LoadableData>
158   GetLoadableData(lldb_private::Target &target) override;
159 
160 private:
161   ObjectFileELF(const lldb::ModuleSP &module_sp, lldb::DataBufferSP &data_sp,
162                 lldb::offset_t data_offset, const lldb_private::FileSpec *file,
163                 lldb::offset_t offset, lldb::offset_t length);
164 
165   ObjectFileELF(const lldb::ModuleSP &module_sp,
166                 lldb::DataBufferSP &header_data_sp,
167                 const lldb::ProcessSP &process_sp, lldb::addr_t header_addr);
168 
169   typedef std::vector<elf::ELFProgramHeader> ProgramHeaderColl;
170 
171   struct ELFSectionHeaderInfo : public elf::ELFSectionHeader {
172     lldb_private::ConstString section_name;
173   };
174 
175   typedef std::vector<ELFSectionHeaderInfo> SectionHeaderColl;
176   typedef SectionHeaderColl::iterator SectionHeaderCollIter;
177   typedef SectionHeaderColl::const_iterator SectionHeaderCollConstIter;
178 
179   typedef std::vector<elf::ELFDynamic> DynamicSymbolColl;
180   typedef DynamicSymbolColl::iterator DynamicSymbolCollIter;
181   typedef DynamicSymbolColl::const_iterator DynamicSymbolCollConstIter;
182 
183   typedef std::map<lldb::addr_t, lldb_private::AddressClass>
184       FileAddressToAddressClassMap;
185 
186   /// Version of this reader common to all plugins based on this class.
187   static const uint32_t m_plugin_version = 1;
188   static const uint32_t g_core_uuid_magic;
189 
190   /// ELF file header.
191   elf::ELFHeader m_header;
192 
193   /// ELF build ID.
194   lldb_private::UUID m_uuid;
195 
196   /// ELF .gnu_debuglink file and crc data if available.
197   std::string m_gnu_debuglink_file;
198   uint32_t m_gnu_debuglink_crc = 0;
199 
200   /// Collection of program headers.
201   ProgramHeaderColl m_program_headers;
202 
203   /// Collection of section headers.
204   SectionHeaderColl m_section_headers;
205 
206   /// Collection of symbols from the dynamic table.
207   DynamicSymbolColl m_dynamic_symbols;
208 
209   /// List of file specifications corresponding to the modules (shared
210   /// libraries) on which this object file depends.
211   mutable std::unique_ptr<lldb_private::FileSpecList> m_filespec_up;
212 
213   /// Cached value of the entry point for this module.
214   lldb_private::Address m_entry_point_address;
215 
216   /// The architecture detected from parsing elf file contents.
217   lldb_private::ArchSpec m_arch_spec;
218 
219   /// The address class for each symbol in the elf file
220   FileAddressToAddressClassMap m_address_class_map;
221 
222   /// Returns the index of the given section header.
223   size_t SectionIndex(const SectionHeaderCollIter &I);
224 
225   /// Returns the index of the given section header.
226   size_t SectionIndex(const SectionHeaderCollConstIter &I) const;
227 
228   // Parses the ELF program headers.
229   static size_t GetProgramHeaderInfo(ProgramHeaderColl &program_headers,
230                                      lldb_private::DataExtractor &object_data,
231                                      const elf::ELFHeader &header);
232 
233   // Finds PT_NOTE segments and calculates their crc sum.
234   static uint32_t
235   CalculateELFNotesSegmentsCRC32(const ProgramHeaderColl &program_headers,
236                                  lldb_private::DataExtractor &data);
237 
238   /// Parses all section headers present in this object file and populates
239   /// m_program_headers.  This method will compute the header list only once.
240   /// Returns true iff the headers have been successfully parsed.
241   bool ParseProgramHeaders();
242 
243   /// Parses all section headers present in this object file and populates
244   /// m_section_headers.  This method will compute the header list only once.
245   /// Returns the number of headers parsed.
246   size_t ParseSectionHeaders();
247 
248   lldb::SectionType GetSectionType(const ELFSectionHeaderInfo &H) const;
249 
250   static void ParseARMAttributes(lldb_private::DataExtractor &data,
251                                  uint64_t length,
252                                  lldb_private::ArchSpec &arch_spec);
253 
254   /// Parses the elf section headers and returns the uuid, debug link name,
255   /// crc, archspec.
256   static size_t GetSectionHeaderInfo(SectionHeaderColl &section_headers,
257                                      lldb_private::DataExtractor &object_data,
258                                      const elf::ELFHeader &header,
259                                      lldb_private::UUID &uuid,
260                                      std::string &gnu_debuglink_file,
261                                      uint32_t &gnu_debuglink_crc,
262                                      lldb_private::ArchSpec &arch_spec);
263 
264   /// Scans the dynamic section and locates all dependent modules (shared
265   /// libraries) populating m_filespec_up.  This method will compute the
266   /// dependent module list only once.  Returns the number of dependent
267   /// modules parsed.
268   size_t ParseDependentModules();
269 
270   /// Parses the dynamic symbol table and populates m_dynamic_symbols.  The
271   /// vector retains the order as found in the object file.  Returns the
272   /// number of dynamic symbols parsed.
273   size_t ParseDynamicSymbols();
274 
275   /// Populates m_symtab_up will all non-dynamic linker symbols.  This method
276   /// will parse the symbols only once.  Returns the number of symbols parsed.
277   unsigned ParseSymbolTable(lldb_private::Symtab *symbol_table,
278                             lldb::user_id_t start_id,
279                             lldb_private::Section *symtab);
280 
281   /// Helper routine for ParseSymbolTable().
282   unsigned ParseSymbols(lldb_private::Symtab *symbol_table,
283                         lldb::user_id_t start_id,
284                         lldb_private::SectionList *section_list,
285                         const size_t num_symbols,
286                         const lldb_private::DataExtractor &symtab_data,
287                         const lldb_private::DataExtractor &strtab_data);
288 
289   /// Scans the relocation entries and adds a set of artificial symbols to the
290   /// given symbol table for each PLT slot.  Returns the number of symbols
291   /// added.
292   unsigned ParseTrampolineSymbols(lldb_private::Symtab *symbol_table,
293                                   lldb::user_id_t start_id,
294                                   const ELFSectionHeaderInfo *rela_hdr,
295                                   lldb::user_id_t section_id);
296 
297   void ParseUnwindSymbols(lldb_private::Symtab *symbol_table,
298                           lldb_private::DWARFCallFrameInfo *eh_frame);
299 
300   /// Relocates debug sections
301   unsigned RelocateDebugSections(const elf::ELFSectionHeader *rel_hdr,
302                                  lldb::user_id_t rel_id,
303                                  lldb_private::Symtab *thetab);
304 
305   unsigned ApplyRelocations(lldb_private::Symtab *symtab,
306                             const elf::ELFHeader *hdr,
307                             const elf::ELFSectionHeader *rel_hdr,
308                             const elf::ELFSectionHeader *symtab_hdr,
309                             const elf::ELFSectionHeader *debug_hdr,
310                             lldb_private::DataExtractor &rel_data,
311                             lldb_private::DataExtractor &symtab_data,
312                             lldb_private::DataExtractor &debug_data,
313                             lldb_private::Section *rel_section);
314 
315   /// Loads the section name string table into m_shstr_data.  Returns the
316   /// number of bytes constituting the table.
317   size_t GetSectionHeaderStringTable();
318 
319   /// Utility method for looking up a section given its name.  Returns the
320   /// index of the corresponding section or zero if no section with the given
321   /// name can be found (note that section indices are always 1 based, and so
322   /// section index 0 is never valid).
323   lldb::user_id_t GetSectionIndexByName(const char *name);
324 
325   // Returns the ID of the first section that has the given type.
326   lldb::user_id_t GetSectionIndexByType(unsigned type);
327 
328   /// Returns the section header with the given id or NULL.
329   const ELFSectionHeaderInfo *GetSectionHeaderByIndex(lldb::user_id_t id);
330 
331   /// \name  ELF header dump routines
332   //@{
333   static void DumpELFHeader(lldb_private::Stream *s,
334                             const elf::ELFHeader &header);
335 
336   static void DumpELFHeader_e_ident_EI_DATA(lldb_private::Stream *s,
337                                             unsigned char ei_data);
338 
339   static void DumpELFHeader_e_type(lldb_private::Stream *s,
340                                    elf::elf_half e_type);
341   //@}
342 
343   /// \name ELF program header dump routines
344   //@{
345   void DumpELFProgramHeaders(lldb_private::Stream *s);
346 
347   static void DumpELFProgramHeader(lldb_private::Stream *s,
348                                    const elf::ELFProgramHeader &ph);
349 
350   static void DumpELFProgramHeader_p_type(lldb_private::Stream *s,
351                                           elf::elf_word p_type);
352 
353   static void DumpELFProgramHeader_p_flags(lldb_private::Stream *s,
354                                            elf::elf_word p_flags);
355   //@}
356 
357   /// \name ELF section header dump routines
358   //@{
359   void DumpELFSectionHeaders(lldb_private::Stream *s);
360 
361   static void DumpELFSectionHeader(lldb_private::Stream *s,
362                                    const ELFSectionHeaderInfo &sh);
363 
364   static void DumpELFSectionHeader_sh_type(lldb_private::Stream *s,
365                                            elf::elf_word sh_type);
366 
367   static void DumpELFSectionHeader_sh_flags(lldb_private::Stream *s,
368                                             elf::elf_xword sh_flags);
369   //@}
370 
371   /// ELF dependent module dump routine.
372   void DumpDependentModules(lldb_private::Stream *s);
373 
374   const elf::ELFDynamic *FindDynamicSymbol(unsigned tag);
375 
376   unsigned PLTRelocationType();
377 
378   static lldb_private::Status
379   RefineModuleDetailsFromNote(lldb_private::DataExtractor &data,
380                               lldb_private::ArchSpec &arch_spec,
381                               lldb_private::UUID &uuid);
382 
383   bool AnySegmentHasPhysicalAddress();
384 };
385 
386 #endif // liblldb_ObjectFileELF_h_
387