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
19 namespace mcld {
20
21 //===----------------------------------------------------------------------===//
22 // THMToARMStub
23 //===----------------------------------------------------------------------===//
24 const 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
31 const uint32_t THMToARMStub::TEMPLATE[] = {
32 0x46c04778, // bx pc ... nop
33 0xe51ff004, // ldr pc, [pc, #-4]
34 0x0 // dcd R_ARM_ABS32(X)
35 };
36
THMToARMStub(bool pIsOutputPIC,bool pUsingThumb2)37 THMToARMStub::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
THMToARMStub(const uint32_t * pData,size_t pSize,const_fixup_iterator pBegin,const_fixup_iterator pEnd,bool pUsingThumb2)54 THMToARMStub::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
~THMToARMStub()67 THMToARMStub::~THMToARMStub() {
68 }
69
isMyDuty(const class Relocation & pReloc,uint64_t pSource,uint64_t pTargetSymValue) const70 bool 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
name() const109 const std::string& THMToARMStub::name() const {
110 return m_Name;
111 }
112
getContent() const113 const uint8_t* THMToARMStub::getContent() const {
114 return reinterpret_cast<const uint8_t*>(m_pData);
115 }
116
size() const117 size_t THMToARMStub::size() const {
118 return m_Size;
119 }
120
alignment() const121 size_t THMToARMStub::alignment() const {
122 return 4u;
123 }
124
125 // for T bit of this stub
initSymValue() const126 uint64_t THMToARMStub::initSymValue() const {
127 return 0x1;
128 }
129
doClone()130 Stub* THMToARMStub::doClone() {
131 return new THMToARMStub(
132 m_pData, m_Size, fixup_begin(), fixup_end(), m_bUsingThumb2);
133 }
134
135 } // namespace mcld
136