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      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_SECTION_REL_TABLE_HXX
     18 #define ELF_SECTION_REL_TABLE_HXX
     19 
     20 #include "ELF.h"
     21 #include "ELFHeader.h"
     22 #include "ELFObject.h"
     23 #include "ELFReloc.h"
     24 #include "ELFTypes.h"
     25 
     26 #include <set>
     27 
     28 template <unsigned Bitwidth>
     29 ELFSectionRelTable<Bitwidth>::~ELFSectionRelTable() {
     30   using namespace std;
     31   for (size_t i = 0; i < table.size(); ++i) {
     32     delete table[i];
     33   }
     34 }
     35 
     36 template <unsigned Bitwidth>
     37 void ELFSectionRelTable<Bitwidth>::print() const {
     38   using namespace llvm;
     39 
     40   out() << '\n' << fillformat('=', 79) << '\n';
     41   out().changeColor(raw_ostream::WHITE, true);
     42   out() << "Relocation Table" << '\n';
     43   out().resetColor();
     44 
     45   for (size_t i = 0; i < this->size(); ++i) {
     46     (*this)[i]->print();
     47   }
     48 
     49   out() << fillformat('=', 79) << '\n';
     50 }
     51 
     52 template <unsigned Bitwidth>
     53 template <typename Archiver>
     54 ELFSectionRelTable<Bitwidth> *
     55 ELFSectionRelTable<Bitwidth>::read(Archiver &AR,
     56                                    ELFSectionHeaderTy const *sh) {
     57 
     58   rsl_assert(sh->getType() == SHT_REL || sh->getType() == SHT_RELA);
     59 
     60   llvm::OwningPtr<ELFSectionRelTable> rt(new ELFSectionRelTable());
     61 
     62   // Seek to the start of the table
     63   AR.seek(sh->getOffset(), true);
     64 
     65   // Count the relocation entries
     66   size_t size = sh->getSize() / sh->getEntrySize();
     67 
     68   // Read every relocation entries
     69   if (sh->getType() == SHT_REL) {
     70     rsl_assert(sh->getEntrySize() == TypeTraits<ELFRelocRelTy>::size);
     71     for (size_t i = 0; i < size; ++i) {
     72       rt->table.push_back(ELFRelocTy::readRel(AR, i));
     73     }
     74 
     75   } else {
     76     rsl_assert(sh->getEntrySize() == TypeTraits<ELFRelocRelaTy>::size);
     77     for (size_t i = 0; i < size; ++i) {
     78       rt->table.push_back(ELFRelocTy::readRela(AR, i));
     79     }
     80   }
     81 
     82   if (!AR) {
     83     // Unable to read the table.
     84     return 0;
     85   }
     86 
     87   return rt.take();
     88 }
     89 
     90 template <unsigned Bitwidth>
     91 size_t ELFSectionRelTable<Bitwidth>::
     92 getMaxNumStubs(ELFObjectTy const *obj) const {
     93   switch (obj->getHeader()->getMachine()) {
     94   case EM_ARM:
     95     {
     96       std::set<uint32_t> sym_index_set;
     97 
     98       for (size_t i = 0; i < size(); ++i) {
     99         ELFRelocTy *rel = table[i];
    100 
    101         if (rel->getType() == R_ARM_CALL ||
    102             rel->getType() == R_ARM_THM_CALL) {
    103           sym_index_set.insert(rel->getSymTabIndex());
    104         }
    105       }
    106 
    107       return sym_index_set.size();
    108     }
    109 
    110   case EM_MIPS:
    111     {
    112       std::set<uint32_t> sym_index_set;
    113 
    114       for (size_t i = 0; i < size(); ++i) {
    115         ELFRelocTy *rel = table[i];
    116 
    117         if (rel->getType() == R_MIPS_26) {
    118           sym_index_set.insert(rel->getSymTabIndex());
    119         }
    120       }
    121 
    122       return sym_index_set.size();
    123     }
    124 
    125   case EM_386:
    126   case EM_X86_64:
    127     return 0;
    128 
    129   default:
    130     rsl_assert(0 && "Only support ARM, MIPS, X86, and X86_64 relocation.");
    131     return 0;
    132   }
    133 }
    134 
    135 #endif // ELF_SECTION_REL_TABLE_HXX
    136