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 // Other libraries and framework includes
20 // Project includes
21 #include "lldb/Core/ArchSpec.h"
22 #include "lldb/Symbol/ObjectFile.h"
23 #include "lldb/Utility/FileSpec.h"
24 #include "lldb/Utility/UUID.h"
25 #include "lldb/lldb-private.h"
26 
27 #include "ELFHeader.h"
28 
29 struct ELFNote {
30   elf::elf_word n_namesz;
31   elf::elf_word n_descsz;
32   elf::elf_word n_type;
33 
34   std::string n_name;
35 
36   ELFNote() : n_namesz(0), n_descsz(0), n_type(0) {}
37 
38   /// Parse an ELFNote entry from the given DataExtractor starting at position
39   /// \p offset.
40   ///
41   /// @param[in] data
42   ///    The DataExtractor to read from.
43   ///
44   /// @param[in,out] offset
45   ///    Pointer to an offset in the data.  On return the offset will be
46   ///    advanced by the number of bytes read.
47   ///
48   /// @return
49   ///    True if the ELFRel entry was successfully read and false otherwise.
50   bool Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset);
51 
52   size_t GetByteSize() const {
53     return 12 + llvm::alignTo(n_namesz, 4) + llvm::alignTo(n_descsz, 4);
54   }
55 };
56 
57 //------------------------------------------------------------------------------
58 /// @class ObjectFileELF
59 /// @brief Generic ELF object file reader.
60 ///
61 /// This class provides a generic ELF (32/64 bit) reader plugin implementing the
62 /// ObjectFile protocol.
63 class ObjectFileELF : public lldb_private::ObjectFile {
64 public:
65   ~ObjectFileELF() override;
66 
67   //------------------------------------------------------------------
68   // Static Functions
69   //------------------------------------------------------------------
70   static void Initialize();
71 
72   static void Terminate();
73 
74   static lldb_private::ConstString GetPluginNameStatic();
75 
76   static const char *GetPluginDescriptionStatic();
77 
78   static lldb_private::ObjectFile *
79   CreateInstance(const lldb::ModuleSP &module_sp, lldb::DataBufferSP &data_sp,
80                  lldb::offset_t data_offset, const lldb_private::FileSpec *file,
81                  lldb::offset_t file_offset, lldb::offset_t length);
82 
83   static lldb_private::ObjectFile *CreateMemoryInstance(
84       const lldb::ModuleSP &module_sp, lldb::DataBufferSP &data_sp,
85       const lldb::ProcessSP &process_sp, lldb::addr_t header_addr);
86 
87   static size_t GetModuleSpecifications(const lldb_private::FileSpec &file,
88                                         lldb::DataBufferSP &data_sp,
89                                         lldb::offset_t data_offset,
90                                         lldb::offset_t file_offset,
91                                         lldb::offset_t length,
92                                         lldb_private::ModuleSpecList &specs);
93 
94   static bool MagicBytesMatch(lldb::DataBufferSP &data_sp, lldb::addr_t offset,
95                               lldb::addr_t length);
96 
97   //------------------------------------------------------------------
98   // PluginInterface protocol
99   //------------------------------------------------------------------
100   lldb_private::ConstString GetPluginName() override;
101 
102   uint32_t GetPluginVersion() override;
103 
104   //------------------------------------------------------------------
105   // ObjectFile Protocol.
106   //------------------------------------------------------------------
107   bool ParseHeader() override;
108 
109   bool SetLoadAddress(lldb_private::Target &target, lldb::addr_t value,
110                       bool value_is_offset) override;
111 
112   lldb::ByteOrder GetByteOrder() const override;
113 
114   bool IsExecutable() const override;
115 
116   uint32_t GetAddressByteSize() const override;
117 
118   lldb::AddressClass GetAddressClass(lldb::addr_t file_addr) override;
119 
120   lldb_private::Symtab *GetSymtab() override;
121 
122   bool IsStripped() override;
123 
124   void CreateSections(lldb_private::SectionList &unified_section_list) override;
125 
126   void Dump(lldb_private::Stream *s) override;
127 
128   bool GetArchitecture(lldb_private::ArchSpec &arch) override;
129 
130   bool GetUUID(lldb_private::UUID *uuid) override;
131 
132   lldb_private::FileSpecList GetDebugSymbolFilePaths() override;
133 
134   uint32_t GetDependentModules(lldb_private::FileSpecList &files) override;
135 
136   lldb_private::Address
137   GetImageInfoAddress(lldb_private::Target *target) override;
138 
139   lldb_private::Address GetEntryPointAddress() override;
140 
141   ObjectFile::Type CalculateType() override;
142 
143   ObjectFile::Strata CalculateStrata() override;
144 
145   // Returns number of program headers found in the ELF file.
146   size_t GetProgramHeaderCount();
147 
148   // Returns the program header with the given index.
149   const elf::ELFProgramHeader *GetProgramHeaderByIndex(lldb::user_id_t id);
150 
151   // Returns segment data for the given index.
152   lldb_private::DataExtractor GetSegmentDataByIndex(lldb::user_id_t id);
153 
154   llvm::StringRef
155   StripLinkerSymbolAnnotations(llvm::StringRef symbol_name) const 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 
301   unsigned RelocateSection(lldb_private::Symtab *symtab,
302                            const elf::ELFHeader *hdr,
303                            const elf::ELFSectionHeader *rel_hdr,
304                            const elf::ELFSectionHeader *symtab_hdr,
305                            const elf::ELFSectionHeader *debug_hdr,
306                            lldb_private::DataExtractor &rel_data,
307                            lldb_private::DataExtractor &symtab_data,
308                            lldb_private::DataExtractor &debug_data,
309                            lldb_private::Section *rel_section);
310 
311   /// Loads the section name string table into m_shstr_data.  Returns the
312   /// number of bytes constituting the table.
313   size_t GetSectionHeaderStringTable();
314 
315   /// Utility method for looking up a section given its name.  Returns the
316   /// index of the corresponding section or zero if no section with the given
317   /// name can be found (note that section indices are always 1 based, and so
318   /// section index 0 is never valid).
319   lldb::user_id_t GetSectionIndexByName(const char *name);
320 
321   // Returns the ID of the first section that has the given type.
322   lldb::user_id_t GetSectionIndexByType(unsigned type);
323 
324   /// Returns the section header with the given id or NULL.
325   const ELFSectionHeaderInfo *GetSectionHeaderByIndex(lldb::user_id_t id);
326 
327   /// @name  ELF header dump routines
328   //@{
329   static void DumpELFHeader(lldb_private::Stream *s,
330                             const elf::ELFHeader &header);
331 
332   static void DumpELFHeader_e_ident_EI_DATA(lldb_private::Stream *s,
333                                             unsigned char ei_data);
334 
335   static void DumpELFHeader_e_type(lldb_private::Stream *s,
336                                    elf::elf_half e_type);
337   //@}
338 
339   /// @name ELF program header dump routines
340   //@{
341   void DumpELFProgramHeaders(lldb_private::Stream *s);
342 
343   static void DumpELFProgramHeader(lldb_private::Stream *s,
344                                    const elf::ELFProgramHeader &ph);
345 
346   static void DumpELFProgramHeader_p_type(lldb_private::Stream *s,
347                                           elf::elf_word p_type);
348 
349   static void DumpELFProgramHeader_p_flags(lldb_private::Stream *s,
350                                            elf::elf_word p_flags);
351   //@}
352 
353   /// @name ELF section header dump routines
354   //@{
355   void DumpELFSectionHeaders(lldb_private::Stream *s);
356 
357   static void DumpELFSectionHeader(lldb_private::Stream *s,
358                                    const ELFSectionHeaderInfo &sh);
359 
360   static void DumpELFSectionHeader_sh_type(lldb_private::Stream *s,
361                                            elf::elf_word sh_type);
362 
363   static void DumpELFSectionHeader_sh_flags(lldb_private::Stream *s,
364                                             elf::elf_xword sh_flags);
365   //@}
366 
367   /// ELF dependent module dump routine.
368   void DumpDependentModules(lldb_private::Stream *s);
369 
370   const elf::ELFDynamic *FindDynamicSymbol(unsigned tag);
371 
372   unsigned PLTRelocationType();
373 
374   static lldb_private::Status
375   RefineModuleDetailsFromNote(lldb_private::DataExtractor &data,
376                               lldb_private::ArchSpec &arch_spec,
377                               lldb_private::UUID &uuid);
378 };
379 
380 #endif // liblldb_ObjectFileELF_h_
381