ARMToARMStub.cpp revision a790f0a8f3175183bea088389b3e4ae41813e192 
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 <llvm/Support/ELF.h>
14#include <mcld/LD/ResolveInfo.h>
15#include <mcld/LD/LDSymbol.h>
16#include <mcld/Fragment/Relocation.h>
17
18using namespace mcld;
19
20//===----------------------------------------------------------------------===//
21// ARMToARMStub
22//===----------------------------------------------------------------------===//
23const uint32_t ARMToARMStub::PIC_TEMPLATE[] = {
24  0xe59fc000, // ldr   r12, [pc]
25  0xe08ff00c, // add   pc, pc, ip
26  0x0         // dcd   R_ARM_REL32(X-4)
27};
28
29const uint32_t ARMToARMStub::TEMPLATE[] = {
30  0xe51ff004, // ldr   pc, [pc, #-4]
31  0x0         // dcd   R_ARM_ABS32(X)
32};
33
34ARMToARMStub::ARMToARMStub(bool pIsOutputPIC)
35 : m_pData(NULL), m_Name("A2A_prototype"), m_Size(0x0)
36{
37  if (pIsOutputPIC) {
38    m_pData = PIC_TEMPLATE;
39    m_Size = sizeof(PIC_TEMPLATE);
40    addFixup(8u, -4, llvm::ELF::R_ARM_REL32);
41  }
42  else {
43    m_pData = TEMPLATE;
44    m_Size = sizeof(TEMPLATE);
45    addFixup(4u, 0x0, llvm::ELF::R_ARM_ABS32);
46  }
47}
48
49/// for doClone
50ARMToARMStub::ARMToARMStub(const uint32_t* pData,
51                           size_t pSize,
52                           const_fixup_iterator pBegin,
53                           const_fixup_iterator pEnd)
54 : m_pData(pData), m_Name("A2A_veneer"), m_Size(pSize)
55{
56  for (const_fixup_iterator it = pBegin, ie = pEnd; it != ie; ++it)
57    addFixup(**it);
58}
59
60ARMToARMStub::~ARMToARMStub()
61{
62}
63
64bool ARMToARMStub::isMyDuty(const class Relocation& pReloc,
65                            uint64_t pSource,
66                            uint64_t pTargetSymValue) const
67{
68  bool result = false;
69  // Check if the branch target is ARM
70  if ((pTargetSymValue & 0x1) == 0x0) {
71    switch (pReloc.type()) {
72      case llvm::ELF::R_ARM_PC24:
73      case llvm::ELF::R_ARM_CALL:
74      case llvm::ELF::R_ARM_JUMP24:
75      case llvm::ELF::R_ARM_PLT32: {
76        // Check if the branch target is too far
77        uint64_t dest = pTargetSymValue + pReloc.addend() + 8u;
78        int64_t branch_offset = static_cast<int64_t>(dest) - pSource;
79        if ((branch_offset > ARMGNULDBackend::ARM_MAX_FWD_BRANCH_OFFSET) ||
80            (branch_offset < ARMGNULDBackend::ARM_MAX_BWD_BRANCH_OFFSET)) {
81          result =  true;
82        }
83        break;
84      }
85      default:
86        break;
87    }
88  }
89  return result;
90}
91
92const std::string& ARMToARMStub::name() const
93{
94  return m_Name;
95}
96
97const uint8_t* ARMToARMStub::getContent() const
98{
99  return reinterpret_cast<const uint8_t*>(m_pData);
100}
101
102size_t ARMToARMStub::size() const
103{
104  return m_Size;
105}
106
107size_t ARMToARMStub::alignment() const
108{
109  return 4u;
110}
111
112Stub* ARMToARMStub::doClone()
113{
114  return new ARMToARMStub(m_pData, m_Size, fixup_begin(), fixup_end());
115}
116