ELFObject.hxx revision 52b519a2d1b0a29b8e76230ee7f9625fd25dda2a 
1/*
2 * Copyright 2011, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ELF_OBJECT_HXX
18#define ELF_OBJECT_HXX
19
20#include "ELFHeader.h"
21#include "ELFReloc.h"
22#include "ELFSection.h"
23#include "ELFSectionHeaderTable.h"
24#include "StubLayout.h"
25#include "ELF.h"
26
27#include <llvm/ADT/SmallVector.h>
28
29#include "utils/rsl_assert.h"
30
31template <unsigned Bitwidth>
32template <typename Archiver>
33inline ELFObject<Bitwidth> *
34ELFObject<Bitwidth>::read(Archiver &AR) {
35  llvm::OwningPtr<ELFObjectTy> object(new ELFObjectTy());
36
37  // Read header
38  object->header.reset(ELFHeaderTy::read(AR));
39  if (!object->header) {
40    return 0;
41  }
42
43  // Read section table
44  object->shtab.reset(ELFSectionHeaderTableTy::read(AR, object.get()));
45  if (!object->shtab) {
46    return 0;
47  }
48
49  // Read each section
50  llvm::SmallVector<size_t, 4> progbits_ndx;
51  for (size_t i = 0; i < object->header->getSectionHeaderNum(); ++i) {
52    if ((*object->shtab)[i]->getType() == SHT_PROGBITS) {
53      object->stab.push_back(NULL);
54      progbits_ndx.push_back(i);
55    } else {
56      llvm::OwningPtr<ELFSectionTy> sec(
57        ELFSectionTy::read(AR, object.get(), (*object->shtab)[i]));
58      object->stab.push_back(sec.take());
59    }
60  }
61
62  object->shtab->buildNameMap();
63  ELFSectionSymTabTy *symtab =
64    static_cast<ELFSectionSymTabTy *>(object->getSectionByName(".symtab"));
65  rsl_assert(symtab && "Symtab is required.");
66  symtab->buildNameMap();
67
68  for (size_t i = 0; i < progbits_ndx.size(); ++i) {
69    size_t index = progbits_ndx[i];
70
71    llvm::OwningPtr<ELFSectionTy> sec(
72      ELFSectionTy::read(AR, object.get(), (*object->shtab)[index]));
73    object->stab[index] = sec.take();
74  }
75
76  return object.take();
77}
78
79template <unsigned Bitwidth>
80inline char const *ELFObject<Bitwidth>::getSectionName(size_t i) const {
81  ELFSectionTy const *sec = stab[header->getStringSectionIndex()];
82
83  if (sec) {
84    ELFSectionStrTabTy const &st =
85      static_cast<ELFSectionStrTabTy const &>(*sec);
86    return st[i];
87  }
88
89  return NULL;
90}
91
92template <unsigned Bitwidth>
93inline ELFSection<Bitwidth> const *
94ELFObject<Bitwidth>::getSectionByIndex(size_t i) const {
95  return stab[i];
96}
97
98template <unsigned Bitwidth>
99inline ELFSection<Bitwidth> *
100ELFObject<Bitwidth>::getSectionByIndex(size_t i) {
101  return stab[i];
102}
103
104template <unsigned Bitwidth>
105inline ELFSection<Bitwidth> const *
106ELFObject<Bitwidth>::getSectionByName(std::string const &str) const {
107  size_t idx = getSectionHeaderTable()->getByName(str)->getIndex();
108  return stab[idx];
109}
110
111template <unsigned Bitwidth>
112inline ELFSection<Bitwidth> *
113ELFObject<Bitwidth>::getSectionByName(std::string const &str) {
114  ELFObjectTy const *const_this = this;
115  ELFSectionTy const *sptr = const_this->getSectionByName(str);
116  // Const cast for the same API's const and non-const versions.
117  return const_cast<ELFSectionTy *>(sptr);
118}
119
120
121template <unsigned Bitwidth>
122inline void ELFObject<Bitwidth>::
123relocateARM(void *(*find_sym)(void *context, char const *name),
124            void *context,
125            ELFSectionRelTableTy *reltab,
126            ELFSectionProgBitsTy *text) {
127  // FIXME: Should be implement in independent files.
128  rsl_assert(Bitwidth == 32 && "ARM only have 32 bits.");
129
130  ELFSectionSymTabTy *symtab =
131    static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
132  rsl_assert(symtab && "Symtab is required.");
133
134  for (size_t i = 0; i < reltab->size(); ++i) {
135    // FIXME: Can not implement here, use Fixup!
136    ELFRelocTy *rel = (*reltab)[i];
137    ELFSymbolTy *sym = (*symtab)[rel->getSymTabIndex()];
138
139    // FIXME: May be not uint32_t *.
140    typedef int32_t Inst_t;
141    Inst_t *inst = (Inst_t *)&(*text)[rel->getOffset()];
142    Inst_t P = (Inst_t)(int64_t)inst;
143    Inst_t A = 0;
144    Inst_t S = (Inst_t)(int64_t)sym->getAddress();
145
146    switch (rel->getType()) {
147    default:
148      rsl_assert(0 && "Not implemented relocation type.");
149      break;
150
151    case R_ARM_ABS32:
152      {
153        A = *inst;
154        *inst = (S+A);
155      }
156      break;
157
158      // FIXME: Predefine relocation codes.
159    case R_ARM_CALL:
160      {
161#define SIGN_EXTEND(x, l) (((x)^(1<<((l)-1)))-(1<<(l-1)))
162        A = (Inst_t)(int64_t)SIGN_EXTEND(*inst & 0xFFFFFF, 24);
163#undef SIGN_EXTEND
164
165        switch (sym->getType()) {
166        default:
167          rsl_assert(0 && "Wrong type for R_ARM_CALL relocation.");
168          abort();
169          break;
170
171        case STT_FUNC:
172          if (S == 0) {
173            rsl_assert(0 && "We should get function address at previous "
174                   "sym->getAddress() function call.");
175            abort();
176          }
177          break;
178
179        case STT_NOTYPE:
180          if (S == 0) {
181            void *ext_func = find_sym(context, sym->getName());
182#ifdef SUPPORT_NEAR_JUMP_EVEN_IF_BLc2BLX_NEEDED
183            S = (Inst_t)(uintptr_t)ext_func;
184            sym->setAddress(ext_func);
185
186            uint32_t result = (S >> 2) - (P >> 2) + A;
187            if (result > 0x007fffff && result < 0xff800000) {
188#endif
189#ifndef __arm__
190              // We have not implement function stub in this runtime env
191              rsl_assert(0 && "Target address is far from call instruction");
192              abort();
193#else
194              void *stub = text->getStubLayout()->allocateStub(ext_func);
195              if (!stub) {
196                llvm::errs() << "unable to allocate stub." << "\n";
197                exit(EXIT_FAILURE);
198              }
199
200              //out() << "stub: for " << ext_func << " at " << stub << "\n";
201              sym->setAddress(stub);
202              S = (uint32_t)stub;
203#endif
204#ifdef SUPPORT_NEAR_JUMP_EVEN_IF_BLc2BLX_NEEDED
205            }
206#endif
207          }
208          break;
209        }
210
211        uint32_t result = (S >> 2) - (P >> 2) + A;
212
213        if (result > 0x007fffff && result < 0xff800000) {
214          rsl_assert(0 && "Stub is still too far");
215          abort();
216        }
217
218        *inst = ((result) & 0x00FFFFFF) | (*inst & 0xFF000000);
219      }
220      break;
221    case R_ARM_MOVT_ABS:
222    case R_ARM_MOVW_ABS_NC:
223      {
224        if (S==0 && sym->getType() == STT_NOTYPE)
225        {
226          void *ext_sym = find_sym(context, sym->getName());
227          S = (Inst_t)(uintptr_t)ext_sym;
228          sym->setAddress(ext_sym);
229        }
230        if (rel->getType() == R_ARM_MOVT_ABS) {
231          S >>= 16;
232        }
233
234        // No need sign extend.
235        A = ((*inst & 0xF0000) >> 4) | (*inst & 0xFFF);
236        uint32_t result = (S+A);
237        *inst = (((result) & 0xF000) << 4) |
238          ((result) & 0xFFF) |
239          (*inst & 0xFFF0F000);
240      }
241      break;
242    }
243    //llvm::errs() << "S:     " << (void *)S << '\n';
244    //llvm::errs() << "A:     " << (void *)A << '\n';
245    //llvm::errs() << "P:     " << (void *)P << '\n';
246    //llvm::errs() << "S+A:   " << (void *)(S+A) << '\n';
247    //llvm::errs() << "S+A-P: " << (void *)(S+A-P) << '\n';
248  }
249}
250
251template <unsigned Bitwidth>
252inline void ELFObject<Bitwidth>::
253relocateX86_64(void *(*find_sym)(void *context, char const *name),
254               void *context,
255               ELFSectionRelTableTy *reltab,
256               ELFSectionProgBitsTy *text) {
257  rsl_assert(Bitwidth == 64 && "Only support X86_64.");
258
259  ELFSectionSymTabTy *symtab =
260    static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
261  rsl_assert(symtab && "Symtab is required.");
262
263  for (size_t i = 0; i < reltab->size(); ++i) {
264    // FIXME: Can not implement here, use Fixup!
265    ELFRelocTy *rel = (*reltab)[i];
266    ELFSymbolTy *sym = (*symtab)[rel->getSymTabIndex()];
267
268    //typedef uint64_t Inst_t;
269    typedef int32_t Inst_t;
270    Inst_t *inst = (Inst_t *)&(*text)[rel->getOffset()];
271    Inst_t P = (Inst_t)(int64_t)inst;
272    Inst_t A = (Inst_t)(int64_t)rel->getAddend();
273    Inst_t S = (Inst_t)(int64_t)sym->getAddress();
274
275    if (S == 0) {
276      S = (Inst_t)(int64_t)find_sym(context, sym->getName());
277      sym->setAddress((void *)S);
278    }
279
280    switch (rel->getType()) {
281      default:
282        rsl_assert(0 && "Not implemented relocation type.");
283        break;
284
285      // FIXME: XXX: R_X86_64_64 is 64 bit, there is a big problem here.
286      case 1: // R_X86_64_64
287        *inst = (S+A);
288        break;
289
290      case 2: // R_X86_64_PC32
291        *inst = (S+A-P);
292        break;
293
294      case 10: // R_X86_64_32
295      case 11: // R_X86_64_32S
296        *inst = (S+A);
297        break;
298    }
299  }
300}
301
302template <unsigned Bitwidth>
303inline void ELFObject<Bitwidth>::
304relocateX86_32(void *(*find_sym)(void *context, char const *name),
305               void *context,
306               ELFSectionRelTableTy *reltab,
307               ELFSectionProgBitsTy *text) {
308  rsl_assert(Bitwidth == 32 && "Only support X86.");
309
310  ELFSectionSymTabTy *symtab =
311    static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
312  rsl_assert(symtab && "Symtab is required.");
313
314  for (size_t i = 0; i < reltab->size(); ++i) {
315    // FIXME: Can not implement here, use Fixup!
316    ELFRelocTy *rel = (*reltab)[i];
317    ELFSymbolTy *sym = (*symtab)[rel->getSymTabIndex()];
318
319    //typedef uint64_t Inst_t;
320    typedef int32_t Inst_t;
321    Inst_t *inst = (Inst_t *)&(*text)[rel->getOffset()];
322    Inst_t P = (Inst_t)(uintptr_t)inst;
323    Inst_t A = (Inst_t)(uintptr_t)*inst;
324    Inst_t S = (Inst_t)(uintptr_t)sym->getAddress();
325
326    if (S == 0) {
327      S = (Inst_t)(uintptr_t)find_sym(context, sym->getName());
328      sym->setAddress((void *)S);
329    }
330
331    switch (rel->getType()) {
332    default:
333      rsl_assert(0 && "Not implemented relocation type.");
334      break;
335
336    case R_386_PC32:
337      *inst = (S+A-P);
338      break;
339
340    case R_386_32:
341      *inst = (S+A);
342      break;
343    }
344  }
345}
346
347// TODO: Refactor all relocations.
348template <unsigned Bitwidth>
349inline void ELFObject<Bitwidth>::
350relocate(void *(*find_sym)(void *context, char const *name), void *context) {
351  // Init SHNCommonDataSize.
352  // Need refactoring
353  size_t SHNCommonDataSize = 0;
354
355  ELFSectionSymTabTy *symtab =
356    static_cast<ELFSectionSymTabTy *>(getSectionByName(".symtab"));
357  rsl_assert(symtab && "Symtab is required.");
358
359  for (size_t i = 0; i < symtab->size(); ++i) {
360    ELFSymbolTy *sym = (*symtab)[i];
361
362    if (sym->getType() != STT_OBJECT) {
363      continue;
364    }
365
366    size_t idx = (size_t)sym->getSectionIndex();
367    switch (idx) {
368    default:
369      if ((*shtab)[idx]->getType() == SHT_NOBITS) {
370        // FIXME(logan): This is a workaround for .lcomm directives
371        // bug of LLVM ARM MC code generator.  Remove this when the
372        // LLVM bug is fixed.
373
374        size_t align = 16;
375        SHNCommonDataSize += (size_t)sym->getSize() + align;
376      }
377      break;
378
379    case SHN_COMMON:
380      {
381        size_t align = (size_t)sym->getValue();
382        SHNCommonDataSize += (size_t)sym->getSize() + align;
383      }
384      break;
385
386    case SHN_ABS:
387    case SHN_UNDEF:
388    case SHN_XINDEX:
389      break;
390    }
391  }
392  if (!initSHNCommonDataSize(SHNCommonDataSize)) {
393    rsl_assert("Allocate memory for common variable fail!");
394  }
395
396  for (size_t i = 0; i < stab.size(); ++i) {
397    ELFSectionHeaderTy *sh = (*shtab)[i];
398    if (sh->getType() != SHT_REL && sh->getType() != SHT_RELA) {
399      continue;
400    }
401    ELFSectionRelTableTy *reltab =
402      static_cast<ELFSectionRelTableTy *>(stab[i]);
403    rsl_assert(reltab && "Relocation section can't be NULL.");
404
405    const char *reltab_name = sh->getName();
406    const char *need_rel_name;
407    if (sh->getType() == SHT_REL) {
408      need_rel_name = reltab_name + 4;
409      // ".rel.xxxx"
410      //      ^ start from here.
411    } else {
412      need_rel_name = reltab_name + 5;
413    }
414
415    ELFSectionProgBitsTy *need_rel =
416      static_cast<ELFSectionProgBitsTy *>(getSectionByName(need_rel_name));
417    rsl_assert(need_rel && "Need be relocated section can't be NULL.");
418
419    switch (getHeader()->getMachine()) {
420      case EM_ARM:
421        relocateARM(find_sym, context, reltab, need_rel);
422        break;
423      case EM_386:
424        relocateX86_32(find_sym, context, reltab, need_rel);
425        break;
426      case EM_X86_64:
427        relocateX86_64(find_sym, context, reltab, need_rel);
428        break;
429
430      default:
431        rsl_assert(0 && "Only support ARM, X86, and X86_64 relocation.");
432        break;
433    }
434  }
435
436  for (size_t i = 0; i < stab.size(); ++i) {
437    ELFSectionHeaderTy *sh = (*shtab)[i];
438    if (sh->getType() == SHT_PROGBITS || sh->getType() == SHT_NOBITS) {
439      if (stab[i]) {
440        static_cast<ELFSectionBitsTy *>(stab[i])->protect();
441      }
442    }
443  }
444}
445
446template <unsigned Bitwidth>
447inline void ELFObject<Bitwidth>::print() const {
448  header->print();
449  shtab->print();
450
451  for (size_t i = 0; i < stab.size(); ++i) {
452    ELFSectionTy *sec = stab[i];
453    if (sec) {
454      sec->print();
455    }
456  }
457}
458
459#endif // ELF_OBJECT_HXX
460