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      1 //===- ARMToARMStub.cpp ---------------------------------------------------===//
      2 //
      3 //                     The MCLinker Project
      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 "ARMToARMStub.h"
     11 #include "ARMLDBackend.h"
     12 
     13 #include "mcld/Fragment/Relocation.h"
     14 #include "mcld/LD/LDSymbol.h"
     15 #include "mcld/LD/ResolveInfo.h"
     16 
     17 #include <llvm/Support/ELF.h>
     18 
     19 namespace mcld {
     20 
     21 //===----------------------------------------------------------------------===//
     22 // ARMToARMStub
     23 //===----------------------------------------------------------------------===//
     24 const uint32_t ARMToARMStub::PIC_TEMPLATE[] = {
     25     0xe59fc000,  // ldr   r12, [pc]
     26     0xe08ff00c,  // add   pc, pc, ip
     27     0x0          // dcd   R_ARM_REL32(X-4)
     28 };
     29 
     30 const uint32_t ARMToARMStub::TEMPLATE[] = {
     31     0xe51ff004,  // ldr   pc, [pc, #-4]
     32     0x0          // dcd   R_ARM_ABS32(X)
     33 };
     34 
     35 ARMToARMStub::ARMToARMStub(bool pIsOutputPIC)
     36     : m_pData(NULL), m_Name("A2A_prototype"), m_Size(0x0) {
     37   if (pIsOutputPIC) {
     38     m_pData = PIC_TEMPLATE;
     39     m_Size = sizeof(PIC_TEMPLATE);
     40     addFixup(8u, -4, llvm::ELF::R_ARM_REL32);
     41   } else {
     42     m_pData = TEMPLATE;
     43     m_Size = sizeof(TEMPLATE);
     44     addFixup(4u, 0x0, llvm::ELF::R_ARM_ABS32);
     45   }
     46 }
     47 
     48 /// for doClone
     49 ARMToARMStub::ARMToARMStub(const uint32_t* pData,
     50                            size_t pSize,
     51                            const_fixup_iterator pBegin,
     52                            const_fixup_iterator pEnd)
     53     : m_pData(pData), m_Name("A2A_veneer"), m_Size(pSize) {
     54   for (const_fixup_iterator it = pBegin, ie = pEnd; it != ie; ++it)
     55     addFixup(**it);
     56 }
     57 
     58 ARMToARMStub::~ARMToARMStub() {
     59 }
     60 
     61 bool ARMToARMStub::isMyDuty(const class Relocation& pReloc,
     62                             uint64_t pSource,
     63                             uint64_t pTargetSymValue) const {
     64   bool result = false;
     65   // Check if the branch target is ARM
     66   if ((pTargetSymValue & 0x1) == 0x0) {
     67     switch (pReloc.type()) {
     68       case llvm::ELF::R_ARM_PC24:
     69       case llvm::ELF::R_ARM_CALL:
     70       case llvm::ELF::R_ARM_JUMP24:
     71       case llvm::ELF::R_ARM_PLT32: {
     72         // Check if the branch target is too far
     73         uint64_t dest = pTargetSymValue + pReloc.addend() + 8u;
     74         int64_t branch_offset = static_cast<int64_t>(dest) - pSource;
     75         if ((branch_offset > ARMGNULDBackend::ARM_MAX_FWD_BRANCH_OFFSET) ||
     76             (branch_offset < ARMGNULDBackend::ARM_MAX_BWD_BRANCH_OFFSET)) {
     77           result = true;
     78         }
     79         break;
     80       }
     81       default:
     82         break;
     83     }
     84   }
     85   return result;
     86 }
     87 
     88 const std::string& ARMToARMStub::name() const {
     89   return m_Name;
     90 }
     91 
     92 const uint8_t* ARMToARMStub::getContent() const {
     93   return reinterpret_cast<const uint8_t*>(m_pData);
     94 }
     95 
     96 size_t ARMToARMStub::size() const {
     97   return m_Size;
     98 }
     99 
    100 size_t ARMToARMStub::alignment() const {
    101   return 4u;
    102 }
    103 
    104 Stub* ARMToARMStub::doClone() {
    105   return new ARMToARMStub(m_pData, m_Size, fixup_begin(), fixup_end());
    106 }
    107 
    108 }  // namespace mcld
    109