1 //===-- ELFHeader.cpp ----------------------------------------- -*- 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 #include <cstring>
11 
12 #include "lldb/Core/DataExtractor.h"
13 #include "lldb/Core/Section.h"
14 #include "lldb/Core/Stream.h"
15 
16 #include "ELFHeader.h"
17 
18 using namespace elf;
19 using namespace lldb;
20 using namespace llvm::ELF;
21 
22 //------------------------------------------------------------------------------
23 // Static utility functions.
24 //
25 // GetMaxU64 and GetMaxS64 wrap the similarly named methods from DataExtractor
26 // with error handling code and provide for parsing a sequence of values.
27 static bool
28 GetMaxU64(const lldb_private::DataExtractor &data,
29           lldb::offset_t *offset,
30           uint64_t *value,
31           uint32_t byte_size)
32 {
33     const lldb::offset_t saved_offset = *offset;
34     *value = data.GetMaxU64(offset, byte_size);
35     return *offset != saved_offset;
36 }
37 
38 static bool
39 GetMaxU64(const lldb_private::DataExtractor &data,
40           lldb::offset_t *offset,
41           uint64_t *value,
42           uint32_t byte_size,
43           uint32_t count)
44 {
45     lldb::offset_t saved_offset = *offset;
46 
47     for (uint32_t i = 0; i < count; ++i, ++value)
48     {
49         if (GetMaxU64(data, offset, value, byte_size) == false)
50         {
51             *offset = saved_offset;
52             return false;
53         }
54     }
55     return true;
56 }
57 
58 static bool
59 GetMaxS64(const lldb_private::DataExtractor &data,
60           lldb::offset_t *offset,
61           int64_t *value,
62           uint32_t byte_size)
63 {
64     const lldb::offset_t saved_offset = *offset;
65     *value = data.GetMaxS64(offset, byte_size);
66     return *offset != saved_offset;
67 }
68 
69 static bool
70 GetMaxS64(const lldb_private::DataExtractor &data,
71           lldb::offset_t *offset,
72           int64_t *value,
73           uint32_t byte_size,
74           uint32_t count)
75 {
76     lldb::offset_t saved_offset = *offset;
77 
78     for (uint32_t i = 0; i < count; ++i, ++value)
79     {
80         if (GetMaxS64(data, offset, value, byte_size) == false)
81         {
82             *offset = saved_offset;
83             return false;
84         }
85     }
86     return true;
87 }
88 
89 //------------------------------------------------------------------------------
90 // ELFHeader
91 
92 ELFHeader::ELFHeader()
93 {
94     memset(this, 0, sizeof(ELFHeader));
95 }
96 
97 ByteOrder
98 ELFHeader::GetByteOrder() const
99 {
100     if (e_ident[EI_DATA] == ELFDATA2MSB)
101         return eByteOrderBig;
102     if (e_ident[EI_DATA] == ELFDATA2LSB)
103         return eByteOrderLittle;
104     return eByteOrderInvalid;
105 }
106 
107 bool
108 ELFHeader::Parse(lldb_private::DataExtractor &data, lldb::offset_t *offset)
109 {
110     // Read e_ident.  This provides byte order and address size info.
111     if (data.GetU8(offset, &e_ident, EI_NIDENT) == NULL)
112         return false;
113 
114     const unsigned byte_size = Is32Bit() ? 4 : 8;
115     data.SetByteOrder(GetByteOrder());
116     data.SetAddressByteSize(byte_size);
117 
118     // Read e_type and e_machine.
119     if (data.GetU16(offset, &e_type, 2) == NULL)
120         return false;
121 
122     // Read e_version.
123     if (data.GetU32(offset, &e_version, 1) == NULL)
124         return false;
125 
126     // Read e_entry, e_phoff and e_shoff.
127     if (GetMaxU64(data, offset, &e_entry, byte_size, 3) == false)
128         return false;
129 
130     // Read e_flags.
131     if (data.GetU32(offset, &e_flags, 1) == NULL)
132         return false;
133 
134     // Read e_ehsize, e_phentsize, e_phnum, e_shentsize, e_shnum and
135     // e_shstrndx.
136     if (data.GetU16(offset, &e_ehsize, 6) == NULL)
137         return false;
138 
139     return true;
140 }
141 
142 bool
143 ELFHeader::MagicBytesMatch(const uint8_t *magic)
144 {
145     return memcmp(magic, ElfMagic, strlen(ElfMagic)) == 0;
146 }
147 
148 unsigned
149 ELFHeader::AddressSizeInBytes(const uint8_t *magic)
150 {
151     unsigned address_size = 0;
152 
153     switch (magic[EI_CLASS])
154     {
155     case ELFCLASS32:
156         address_size = 4;
157         break;
158 
159     case ELFCLASS64:
160         address_size = 8;
161         break;
162     }
163     return address_size;
164 }
165 
166 unsigned
167 ELFHeader::GetRelocationJumpSlotType() const
168 {
169     unsigned slot = 0;
170 
171     switch (e_machine)
172     {
173     default:
174         assert(false && "architecture not supported");
175         break;
176     case EM_PPC:
177         slot = R_PPC_JMP_SLOT;
178         break;
179     case EM_PPC64:
180         slot = R_PPC64_JMP_SLOT;
181         break;
182     case EM_386:
183     case EM_486:
184         slot = R_386_JUMP_SLOT;
185         break;
186     case EM_X86_64:
187         slot = R_X86_64_JUMP_SLOT;
188         break;
189     case EM_ARM:
190         slot = R_ARM_JUMP_SLOT;
191         break;
192     case EM_HEXAGON:
193         slot = R_HEX_JMP_SLOT;
194         break;
195     case EM_AARCH64:
196         slot = R_AARCH64_JUMP_SLOT;
197         break;
198     }
199 
200     return slot;
201 }
202 
203 //------------------------------------------------------------------------------
204 // ELFSectionHeader
205 
206 ELFSectionHeader::ELFSectionHeader()
207 {
208     memset(this, 0, sizeof(ELFSectionHeader));
209 }
210 
211 bool
212 ELFSectionHeader::Parse(const lldb_private::DataExtractor &data,
213                         lldb::offset_t *offset)
214 {
215     const unsigned byte_size = data.GetAddressByteSize();
216 
217     // Read sh_name and sh_type.
218     if (data.GetU32(offset, &sh_name, 2) == NULL)
219         return false;
220 
221     // Read sh_flags.
222     if (GetMaxU64(data, offset, &sh_flags, byte_size) == false)
223         return false;
224 
225     // Read sh_addr, sh_off and sh_size.
226     if (GetMaxU64(data, offset, &sh_addr, byte_size, 3) == false)
227         return false;
228 
229     // Read sh_link and sh_info.
230     if (data.GetU32(offset, &sh_link, 2) == NULL)
231         return false;
232 
233     // Read sh_addralign and sh_entsize.
234     if (GetMaxU64(data, offset, &sh_addralign, byte_size, 2) == false)
235         return false;
236 
237     return true;
238 }
239 
240 //------------------------------------------------------------------------------
241 // ELFSymbol
242 
243 ELFSymbol::ELFSymbol()
244 {
245     memset(this, 0, sizeof(ELFSymbol));
246 }
247 
248 #define ENUM_TO_CSTR(e) case e: return #e
249 
250 const char *
251 ELFSymbol::bindingToCString(unsigned char binding)
252 {
253     switch (binding)
254     {
255     ENUM_TO_CSTR(STB_LOCAL);
256     ENUM_TO_CSTR(STB_GLOBAL);
257     ENUM_TO_CSTR(STB_WEAK);
258     ENUM_TO_CSTR(STB_LOOS);
259     ENUM_TO_CSTR(STB_HIOS);
260     ENUM_TO_CSTR(STB_LOPROC);
261     ENUM_TO_CSTR(STB_HIPROC);
262     }
263     return "";
264 }
265 
266 const char *
267 ELFSymbol::typeToCString(unsigned char type)
268 {
269     switch (type)
270     {
271     ENUM_TO_CSTR(STT_NOTYPE);
272     ENUM_TO_CSTR(STT_OBJECT);
273     ENUM_TO_CSTR(STT_FUNC);
274     ENUM_TO_CSTR(STT_SECTION);
275     ENUM_TO_CSTR(STT_FILE);
276     ENUM_TO_CSTR(STT_COMMON);
277     ENUM_TO_CSTR(STT_TLS);
278     ENUM_TO_CSTR(STT_LOOS);
279     ENUM_TO_CSTR(STT_HIOS);
280     ENUM_TO_CSTR(STT_GNU_IFUNC);
281     ENUM_TO_CSTR(STT_LOPROC);
282     ENUM_TO_CSTR(STT_HIPROC);
283     }
284     return "";
285 }
286 
287 const char *
288 ELFSymbol::sectionIndexToCString (elf_half shndx,
289                                   const lldb_private::SectionList *section_list)
290 {
291     switch (shndx)
292     {
293     ENUM_TO_CSTR(SHN_UNDEF);
294     ENUM_TO_CSTR(SHN_LOPROC);
295     ENUM_TO_CSTR(SHN_HIPROC);
296     ENUM_TO_CSTR(SHN_LOOS);
297     ENUM_TO_CSTR(SHN_HIOS);
298     ENUM_TO_CSTR(SHN_ABS);
299     ENUM_TO_CSTR(SHN_COMMON);
300     ENUM_TO_CSTR(SHN_XINDEX);
301     default:
302         {
303             const lldb_private::Section *section = section_list->GetSectionAtIndex(shndx).get();
304             if (section)
305                 return section->GetName().AsCString("");
306         }
307         break;
308     }
309     return "";
310 }
311 
312 void
313 ELFSymbol::Dump (lldb_private::Stream *s,
314                  uint32_t idx,
315                  const lldb_private::DataExtractor *strtab_data,
316                  const lldb_private::SectionList *section_list)
317 {
318     s->Printf("[%3u] 0x%16.16" PRIx64 " 0x%16.16" PRIx64 " 0x%8.8x 0x%2.2x (%-10s %-13s) 0x%2.2x 0x%4.4x (%-10s) %s\n",
319               idx,
320               st_value,
321               st_size,
322               st_name,
323               st_info,
324               bindingToCString (getBinding()),
325               typeToCString (getType()),
326               st_other,
327               st_shndx,
328               sectionIndexToCString (st_shndx, section_list),
329               strtab_data ? strtab_data->PeekCStr(st_name) : "");
330 }
331 
332 bool
333 ELFSymbol::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
334 {
335     const unsigned byte_size = data.GetAddressByteSize();
336     const bool parsing_32 = byte_size == 4;
337 
338     // Read st_name.
339     if (data.GetU32(offset, &st_name, 1) == NULL)
340         return false;
341 
342     if (parsing_32)
343     {
344         // Read st_value and st_size.
345         if (GetMaxU64(data, offset, &st_value, byte_size, 2) == false)
346             return false;
347 
348         // Read st_info and st_other.
349         if (data.GetU8(offset, &st_info, 2) == NULL)
350             return false;
351 
352         // Read st_shndx.
353         if (data.GetU16(offset, &st_shndx, 1) == NULL)
354             return false;
355     }
356     else
357     {
358         // Read st_info and st_other.
359         if (data.GetU8(offset, &st_info, 2) == NULL)
360             return false;
361 
362         // Read st_shndx.
363         if (data.GetU16(offset, &st_shndx, 1) == NULL)
364             return false;
365 
366         // Read st_value and st_size.
367         if (data.GetU64(offset, &st_value, 2) == NULL)
368             return false;
369     }
370     return true;
371 }
372 
373 //------------------------------------------------------------------------------
374 // ELFProgramHeader
375 
376 ELFProgramHeader::ELFProgramHeader()
377 {
378     memset(this, 0, sizeof(ELFProgramHeader));
379 }
380 
381 bool
382 ELFProgramHeader::Parse(const lldb_private::DataExtractor &data,
383                         lldb::offset_t *offset)
384 {
385     const uint32_t byte_size = data.GetAddressByteSize();
386     const bool parsing_32 = byte_size == 4;
387 
388     // Read p_type;
389     if (data.GetU32(offset, &p_type, 1) == NULL)
390         return false;
391 
392     if (parsing_32) {
393         // Read p_offset, p_vaddr, p_paddr, p_filesz and p_memsz.
394         if (GetMaxU64(data, offset, &p_offset, byte_size, 5) == false)
395             return false;
396 
397         // Read p_flags.
398         if (data.GetU32(offset, &p_flags, 1) == NULL)
399             return false;
400 
401         // Read p_align.
402         if (GetMaxU64(data, offset, &p_align, byte_size) == false)
403             return false;
404     }
405     else {
406         // Read p_flags.
407         if (data.GetU32(offset, &p_flags, 1) == NULL)
408             return false;
409 
410         // Read p_offset, p_vaddr, p_paddr, p_filesz, p_memsz and p_align.
411         if (GetMaxU64(data, offset, &p_offset, byte_size, 6) == false)
412             return false;
413     }
414 
415     return true;
416 }
417 
418 //------------------------------------------------------------------------------
419 // ELFDynamic
420 
421 ELFDynamic::ELFDynamic()
422 {
423     memset(this, 0, sizeof(ELFDynamic));
424 }
425 
426 bool
427 ELFDynamic::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
428 {
429     const unsigned byte_size = data.GetAddressByteSize();
430     return GetMaxS64(data, offset, &d_tag, byte_size, 2);
431 }
432 
433 //------------------------------------------------------------------------------
434 // ELFRel
435 
436 ELFRel::ELFRel()
437 {
438     memset(this, 0, sizeof(ELFRel));
439 }
440 
441 bool
442 ELFRel::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
443 {
444     const unsigned byte_size = data.GetAddressByteSize();
445 
446     // Read r_offset and r_info.
447     if (GetMaxU64(data, offset, &r_offset, byte_size, 2) == false)
448         return false;
449 
450     return true;
451 }
452 
453 //------------------------------------------------------------------------------
454 // ELFRela
455 
456 ELFRela::ELFRela()
457 {
458     memset(this, 0, sizeof(ELFRela));
459 }
460 
461 bool
462 ELFRela::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
463 {
464     const unsigned byte_size = data.GetAddressByteSize();
465 
466     // Read r_offset and r_info.
467     if (GetMaxU64(data, offset, &r_offset, byte_size, 2) == false)
468         return false;
469 
470     // Read r_addend;
471     if (GetMaxS64(data, offset, &r_addend, byte_size) == false)
472         return false;
473 
474     return true;
475 }
476 
477 
478