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