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
GetMaxU64(const lldb_private::DataExtractor & data,lldb::offset_t * offset,uint64_t * value,uint32_t byte_size)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
GetMaxU64(const lldb_private::DataExtractor & data,lldb::offset_t * offset,uint64_t * value,uint32_t byte_size,uint32_t count)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
GetMaxS64(const lldb_private::DataExtractor & data,lldb::offset_t * offset,int64_t * value,uint32_t byte_size)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
GetMaxS64(const lldb_private::DataExtractor & data,lldb::offset_t * offset,int64_t * value,uint32_t byte_size,uint32_t count)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
ELFHeader()92 ELFHeader::ELFHeader()
93 {
94 memset(this, 0, sizeof(ELFHeader));
95 }
96
97 ByteOrder
GetByteOrder() const98 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
Parse(lldb_private::DataExtractor & data,lldb::offset_t * offset)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
MagicBytesMatch(const uint8_t * magic)143 ELFHeader::MagicBytesMatch(const uint8_t *magic)
144 {
145 return memcmp(magic, ElfMagic, strlen(ElfMagic)) == 0;
146 }
147
148 unsigned
AddressSizeInBytes(const uint8_t * magic)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
GetRelocationJumpSlotType() const167 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_386:
177 case EM_486:
178 slot = R_386_JUMP_SLOT;
179 break;
180 case EM_X86_64:
181 slot = R_X86_64_JUMP_SLOT;
182 break;
183 case EM_ARM:
184 slot = R_ARM_JUMP_SLOT;
185 break;
186 }
187
188 return slot;
189 }
190
191 //------------------------------------------------------------------------------
192 // ELFSectionHeader
193
ELFSectionHeader()194 ELFSectionHeader::ELFSectionHeader()
195 {
196 memset(this, 0, sizeof(ELFSectionHeader));
197 }
198
199 bool
Parse(const lldb_private::DataExtractor & data,lldb::offset_t * offset)200 ELFSectionHeader::Parse(const lldb_private::DataExtractor &data,
201 lldb::offset_t *offset)
202 {
203 const unsigned byte_size = data.GetAddressByteSize();
204
205 // Read sh_name and sh_type.
206 if (data.GetU32(offset, &sh_name, 2) == NULL)
207 return false;
208
209 // Read sh_flags.
210 if (GetMaxU64(data, offset, &sh_flags, byte_size) == false)
211 return false;
212
213 // Read sh_addr, sh_off and sh_size.
214 if (GetMaxU64(data, offset, &sh_addr, byte_size, 3) == false)
215 return false;
216
217 // Read sh_link and sh_info.
218 if (data.GetU32(offset, &sh_link, 2) == NULL)
219 return false;
220
221 // Read sh_addralign and sh_entsize.
222 if (GetMaxU64(data, offset, &sh_addralign, byte_size, 2) == false)
223 return false;
224
225 return true;
226 }
227
228 //------------------------------------------------------------------------------
229 // ELFSymbol
230
ELFSymbol()231 ELFSymbol::ELFSymbol()
232 {
233 memset(this, 0, sizeof(ELFSymbol));
234 }
235
236 #define ENUM_TO_CSTR(e) case e: return #e
237
238 const char *
bindingToCString(unsigned char binding)239 ELFSymbol::bindingToCString(unsigned char binding)
240 {
241 switch (binding)
242 {
243 ENUM_TO_CSTR(STB_LOCAL);
244 ENUM_TO_CSTR(STB_GLOBAL);
245 ENUM_TO_CSTR(STB_WEAK);
246 ENUM_TO_CSTR(STB_LOOS);
247 ENUM_TO_CSTR(STB_HIOS);
248 ENUM_TO_CSTR(STB_LOPROC);
249 ENUM_TO_CSTR(STB_HIPROC);
250 }
251 return "";
252 }
253
254 const char *
typeToCString(unsigned char type)255 ELFSymbol::typeToCString(unsigned char type)
256 {
257 switch (type)
258 {
259 ENUM_TO_CSTR(STT_NOTYPE);
260 ENUM_TO_CSTR(STT_OBJECT);
261 ENUM_TO_CSTR(STT_FUNC);
262 ENUM_TO_CSTR(STT_SECTION);
263 ENUM_TO_CSTR(STT_FILE);
264 ENUM_TO_CSTR(STT_COMMON);
265 ENUM_TO_CSTR(STT_TLS);
266 ENUM_TO_CSTR(STT_LOOS);
267 ENUM_TO_CSTR(STT_HIOS);
268 ENUM_TO_CSTR(STT_GNU_IFUNC);
269 ENUM_TO_CSTR(STT_LOPROC);
270 ENUM_TO_CSTR(STT_HIPROC);
271 }
272 return "";
273 }
274
275 const char *
sectionIndexToCString(elf_half shndx,const lldb_private::SectionList * section_list)276 ELFSymbol::sectionIndexToCString (elf_half shndx,
277 const lldb_private::SectionList *section_list)
278 {
279 switch (shndx)
280 {
281 ENUM_TO_CSTR(SHN_UNDEF);
282 ENUM_TO_CSTR(SHN_LOPROC);
283 ENUM_TO_CSTR(SHN_HIPROC);
284 ENUM_TO_CSTR(SHN_LOOS);
285 ENUM_TO_CSTR(SHN_HIOS);
286 ENUM_TO_CSTR(SHN_ABS);
287 ENUM_TO_CSTR(SHN_COMMON);
288 ENUM_TO_CSTR(SHN_XINDEX);
289 default:
290 {
291 const lldb_private::Section *section = section_list->GetSectionAtIndex(shndx).get();
292 if (section)
293 return section->GetName().AsCString("");
294 }
295 break;
296 }
297 return "";
298 }
299
300 void
Dump(lldb_private::Stream * s,uint32_t idx,const lldb_private::DataExtractor * strtab_data,const lldb_private::SectionList * section_list)301 ELFSymbol::Dump (lldb_private::Stream *s,
302 uint32_t idx,
303 const lldb_private::DataExtractor *strtab_data,
304 const lldb_private::SectionList *section_list)
305 {
306 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",
307 idx,
308 st_value,
309 st_size,
310 st_name,
311 st_info,
312 bindingToCString (getBinding()),
313 typeToCString (getType()),
314 st_other,
315 st_shndx,
316 sectionIndexToCString (st_shndx, section_list),
317 strtab_data ? strtab_data->PeekCStr(st_name) : "");
318 }
319
320 bool
Parse(const lldb_private::DataExtractor & data,lldb::offset_t * offset)321 ELFSymbol::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
322 {
323 const unsigned byte_size = data.GetAddressByteSize();
324 const bool parsing_32 = byte_size == 4;
325
326 // Read st_name.
327 if (data.GetU32(offset, &st_name, 1) == NULL)
328 return false;
329
330 if (parsing_32)
331 {
332 // Read st_value and st_size.
333 if (GetMaxU64(data, offset, &st_value, byte_size, 2) == false)
334 return false;
335
336 // Read st_info and st_other.
337 if (data.GetU8(offset, &st_info, 2) == NULL)
338 return false;
339
340 // Read st_shndx.
341 if (data.GetU16(offset, &st_shndx, 1) == NULL)
342 return false;
343 }
344 else
345 {
346 // Read st_info and st_other.
347 if (data.GetU8(offset, &st_info, 2) == NULL)
348 return false;
349
350 // Read st_shndx.
351 if (data.GetU16(offset, &st_shndx, 1) == NULL)
352 return false;
353
354 // Read st_value and st_size.
355 if (data.GetU64(offset, &st_value, 2) == NULL)
356 return false;
357 }
358 return true;
359 }
360
361 //------------------------------------------------------------------------------
362 // ELFProgramHeader
363
ELFProgramHeader()364 ELFProgramHeader::ELFProgramHeader()
365 {
366 memset(this, 0, sizeof(ELFProgramHeader));
367 }
368
369 bool
Parse(const lldb_private::DataExtractor & data,lldb::offset_t * offset)370 ELFProgramHeader::Parse(const lldb_private::DataExtractor &data,
371 lldb::offset_t *offset)
372 {
373 const uint32_t byte_size = data.GetAddressByteSize();
374 const bool parsing_32 = byte_size == 4;
375
376 // Read p_type;
377 if (data.GetU32(offset, &p_type, 1) == NULL)
378 return false;
379
380 if (parsing_32) {
381 // Read p_offset, p_vaddr, p_paddr, p_filesz and p_memsz.
382 if (GetMaxU64(data, offset, &p_offset, byte_size, 5) == false)
383 return false;
384
385 // Read p_flags.
386 if (data.GetU32(offset, &p_flags, 1) == NULL)
387 return false;
388
389 // Read p_align.
390 if (GetMaxU64(data, offset, &p_align, byte_size) == false)
391 return false;
392 }
393 else {
394 // Read p_flags.
395 if (data.GetU32(offset, &p_flags, 1) == NULL)
396 return false;
397
398 // Read p_offset, p_vaddr, p_paddr, p_filesz, p_memsz and p_align.
399 if (GetMaxU64(data, offset, &p_offset, byte_size, 6) == false)
400 return false;
401 }
402
403 return true;
404 }
405
406 //------------------------------------------------------------------------------
407 // ELFDynamic
408
ELFDynamic()409 ELFDynamic::ELFDynamic()
410 {
411 memset(this, 0, sizeof(ELFDynamic));
412 }
413
414 bool
Parse(const lldb_private::DataExtractor & data,lldb::offset_t * offset)415 ELFDynamic::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
416 {
417 const unsigned byte_size = data.GetAddressByteSize();
418 return GetMaxS64(data, offset, &d_tag, byte_size, 2);
419 }
420
421 //------------------------------------------------------------------------------
422 // ELFRel
423
ELFRel()424 ELFRel::ELFRel()
425 {
426 memset(this, 0, sizeof(ELFRel));
427 }
428
429 bool
Parse(const lldb_private::DataExtractor & data,lldb::offset_t * offset)430 ELFRel::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
431 {
432 const unsigned byte_size = data.GetAddressByteSize();
433
434 // Read r_offset and r_info.
435 if (GetMaxU64(data, offset, &r_offset, byte_size, 2) == false)
436 return false;
437
438 return true;
439 }
440
441 //------------------------------------------------------------------------------
442 // ELFRela
443
ELFRela()444 ELFRela::ELFRela()
445 {
446 memset(this, 0, sizeof(ELFRela));
447 }
448
449 bool
Parse(const lldb_private::DataExtractor & data,lldb::offset_t * offset)450 ELFRela::Parse(const lldb_private::DataExtractor &data, lldb::offset_t *offset)
451 {
452 const unsigned byte_size = data.GetAddressByteSize();
453
454 // Read r_offset and r_info.
455 if (GetMaxU64(data, offset, &r_offset, byte_size, 2) == false)
456 return false;
457
458 // Read r_addend;
459 if (GetMaxS64(data, offset, &r_addend, byte_size) == false)
460 return false;
461
462 return true;
463 }
464
465
466