1//===- THMToARMStub.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 "THMToARMStub.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
19namespace mcld {
20
21//===----------------------------------------------------------------------===//
22// THMToARMStub
23//===----------------------------------------------------------------------===//
24const uint32_t THMToARMStub::PIC_TEMPLATE[] = {
25    0x46c04778,  // bx    pc ... nop
26    0xe59fc000,  // ldr   ip, [pc, #0]
27    0xe08cf00f,  // add   pc, ip, pc
28    0x0          // dcd   R_ARM_REL32(X)
29};
30
31const uint32_t THMToARMStub::TEMPLATE[] = {
32    0x46c04778,  // bx    pc ... nop
33    0xe51ff004,  // ldr   pc, [pc, #-4]
34    0x0          // dcd   R_ARM_ABS32(X)
35};
36
37THMToARMStub::THMToARMStub(bool pIsOutputPIC, bool pUsingThumb2)
38    : m_pData(NULL),
39      m_Name("T2A_prototype"),
40      m_Size(0x0),
41      m_bUsingThumb2(pUsingThumb2) {
42  if (pIsOutputPIC) {
43    m_pData = PIC_TEMPLATE;
44    m_Size = sizeof(PIC_TEMPLATE);
45    addFixup(12u, -4, llvm::ELF::R_ARM_REL32);
46  } else {
47    m_pData = TEMPLATE;
48    m_Size = sizeof(TEMPLATE);
49    addFixup(8u, 0x0, llvm::ELF::R_ARM_ABS32);
50  }
51}
52
53/// for doClone
54THMToARMStub::THMToARMStub(const uint32_t* pData,
55                           size_t pSize,
56                           const_fixup_iterator pBegin,
57                           const_fixup_iterator pEnd,
58                           bool pUsingThumb2)
59    : m_pData(pData),
60      m_Name("T2A_veneer"),
61      m_Size(pSize),
62      m_bUsingThumb2(pUsingThumb2) {
63  for (const_fixup_iterator it = pBegin, ie = pEnd; it != ie; ++it)
64    addFixup(**it);
65}
66
67THMToARMStub::~THMToARMStub() {
68}
69
70bool THMToARMStub::isMyDuty(const class Relocation& pReloc,
71                            uint64_t pSource,
72                            uint64_t pTargetSymValue) const {
73  bool result = false;
74  // Check if the branch target is ARM
75  if ((pTargetSymValue & 0x1) == 0x0) {
76    switch (pReloc.type()) {
77      case llvm::ELF::R_ARM_THM_CALL: {
78        // FIXME: Assuming blx is available (i.e., target is armv5 or above!)
79        // then, we do not need a stub unless the branch target is too far.
80        uint64_t dest = pTargetSymValue + pReloc.addend() + 4u;
81        int64_t branch_offset = static_cast<int64_t>(dest) - pSource;
82        if (m_bUsingThumb2) {
83          if ((branch_offset > ARMGNULDBackend::THM2_MAX_FWD_BRANCH_OFFSET) ||
84              (branch_offset < ARMGNULDBackend::THM2_MAX_BWD_BRANCH_OFFSET)) {
85            result = true;
86            break;
87          }
88        } else {
89          if ((branch_offset > ARMGNULDBackend::THM_MAX_FWD_BRANCH_OFFSET) ||
90              (branch_offset < ARMGNULDBackend::THM_MAX_BWD_BRANCH_OFFSET)) {
91            result = true;
92            break;
93          }
94        }
95        break;
96      }
97      case llvm::ELF::R_ARM_THM_JUMP24: {
98        // always need a stub to switch mode
99        result = true;
100        break;
101      }
102      default:
103        break;
104    }
105  }
106  return result;
107}
108
109const std::string& THMToARMStub::name() const {
110  return m_Name;
111}
112
113const uint8_t* THMToARMStub::getContent() const {
114  return reinterpret_cast<const uint8_t*>(m_pData);
115}
116
117size_t THMToARMStub::size() const {
118  return m_Size;
119}
120
121size_t THMToARMStub::alignment() const {
122  return 4u;
123}
124
125// for T bit of this stub
126uint64_t THMToARMStub::initSymValue() const {
127  return 0x1;
128}
129
130Stub* THMToARMStub::doClone() {
131  return new THMToARMStub(
132      m_pData, m_Size, fixup_begin(), fixup_end(), m_bUsingThumb2);
133}
134
135}  // namespace mcld
136