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