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 : m_pData(NULL), m_Name("A2T_prototype"), 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 : m_pData(pData), m_Name("A2T_veneer"), 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_PC24:
87      case llvm::ELF::R_ARM_JUMP24:
88      case llvm::ELF::R_ARM_PLT32: {
89        // always need a stub to switch mode
90        result = true;
91        break;
92      }
93      default:
94        break;
95    }
96  }
97  return result;
98}
99
100const std::string& ARMToTHMStub::name() const
101{
102  return m_Name;
103}
104
105const uint8_t* ARMToTHMStub::getContent() const
106{
107  return reinterpret_cast<const uint8_t*>(m_pData);
108}
109
110size_t ARMToTHMStub::size() const
111{
112  return m_Size;
113}
114
115size_t ARMToTHMStub::alignment() const
116{
117  return 4u;
118}
119
120Stub* ARMToTHMStub::doClone()
121{
122  return new ARMToTHMStub(m_pData, m_Size, fixup_begin(), fixup_end());
123}
124