ARMToTHMStub.cpp revision 22add6ff3426df1a85089fe6a6e1597ee3b6f300 
1//===- ARMToTHMStub.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 "ARMToTHMStub.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// ARMToTHMStub
22//===----------------------------------------------------------------------===//
23const uint32_t ARMToTHMStub::PIC_TEMPLATE[] = {
24  0xe59fc004, // ldr   r12, [pc, #4]
25  0xe08fc00c, // add   ip, pc, ip
26  0xe12fff1c, // bx    ip
27  0x0         // dcd   R_ARM_REL32(X)
28};
29
30const uint32_t ARMToTHMStub::TEMPLATE[] = {
31  0xe59fc000, // ldr   ip, [pc, #0]
32  0xe12fff1c, // bx    ip
33  0x0         // dcd   R_ARM_ABS32(X)
34};
35
36ARMToTHMStub::ARMToTHMStub(bool pIsOutputPIC)
37 : Stub(), m_Name("A2T_prototype"), m_pData(NULL), m_Size(0x0)
38{
39  if (pIsOutputPIC) {
40    m_pData = PIC_TEMPLATE;
41    m_Size = sizeof(PIC_TEMPLATE);
42    addFixup(12u, 0x0, llvm::ELF::R_ARM_REL32);
43  }
44  else {
45    m_pData = TEMPLATE;
46    m_Size = sizeof(TEMPLATE);
47    addFixup(8u, 0x0, llvm::ELF::R_ARM_ABS32);
48  }
49}
50
51/// for doClone
52ARMToTHMStub::ARMToTHMStub(const uint32_t* pData,
53                           size_t pSize,
54                           const_fixup_iterator pBegin,
55                           const_fixup_iterator pEnd)
56 : Stub(), m_Name("A2T_veneer"), m_pData(pData), m_Size(pSize)
57{
58  for (const_fixup_iterator it = pBegin, ie = pEnd; it != ie; ++it)
59    addFixup(**it);
60}
61
62ARMToTHMStub::~ARMToTHMStub()
63{
64}
65
66bool ARMToTHMStub::isMyDuty(const class Relocation& pReloc,
67                            uint64_t pSource,
68                            uint64_t pTargetSymValue) const
69{
70  bool result = false;
71  // Check if the branch target is THUMB
72  if ((pTargetSymValue & 0x1) != 0x0) {
73    switch (pReloc.type()) {
74      case llvm::ELF::R_ARM_CALL: {
75        // FIXME: Assuming blx is available (i.e., target is armv5 or above!)
76        // then, we do not need a stub unless 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          break;
83        }
84        break;
85      }
86      case llvm::ELF::R_ARM_JUMP24:
87      case llvm::ELF::R_ARM_PLT32: {
88        // always need a stub to switch mode
89        result = true;
90        break;
91      }
92      default:
93        break;
94    }
95  }
96  return result;
97}
98
99const std::string& ARMToTHMStub::name() const
100{
101  return m_Name;
102}
103
104const uint8_t* ARMToTHMStub::getContent() const
105{
106  return reinterpret_cast<const uint8_t*>(m_pData);
107}
108
109size_t ARMToTHMStub::size() const
110{
111  return m_Size;
112}
113
114size_t ARMToTHMStub::alignment() const
115{
116  return 4u;
117}
118
119Stub* ARMToTHMStub::doClone()
120{
121  return new ARMToTHMStub(m_pData, m_Size, fixup_begin(), fixup_end());
122}
123
124