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 <llvm/Support/ELF.h>
14 #include <mcld/LD/ResolveInfo.h>
15 #include <mcld/LD/LDSymbol.h>
16 #include <mcld/Fragment/Relocation.h>
17
18 using namespace mcld;
19
20 //===----------------------------------------------------------------------===//
21 // THMToARMStub
22 //===----------------------------------------------------------------------===//
23 const uint32_t THMToARMStub::PIC_TEMPLATE[] = {
24 0x46c04778, // bx pc ... nop
25 0xe59fc000, // ldr ip, [pc, #0]
26 0xe08cf00f, // add pc, ip, pc
27 0x0 // dcd R_ARM_REL32(X)
28 };
29
30 const uint32_t THMToARMStub::TEMPLATE[] = {
31 0x46c04778, // bx pc ... nop
32 0xe51ff004, // ldr pc, [pc, #-4]
33 0x0 // dcd R_ARM_ABS32(X)
34 };
35
THMToARMStub(bool pIsOutputPIC,bool pUsingThumb2)36 THMToARMStub::THMToARMStub(bool pIsOutputPIC, bool pUsingThumb2)
37 : m_pData(NULL),
38 m_Name("T2A_prototype"),
39 m_Size(0x0),
40 m_bUsingThumb2(pUsingThumb2)
41 {
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 {
64 for (const_fixup_iterator it = pBegin, ie = pEnd; it != ie; ++it)
65 addFixup(**it);
66 }
67
~THMToARMStub()68 THMToARMStub::~THMToARMStub()
69 {
70 }
71
isMyDuty(const class Relocation & pReloc,uint64_t pSource,uint64_t pTargetSymValue) const72 bool THMToARMStub::isMyDuty(const class Relocation& pReloc,
73 uint64_t pSource,
74 uint64_t pTargetSymValue) const
75 {
76 bool result = false;
77 // Check if the branch target is ARM
78 if ((pTargetSymValue & 0x1) == 0x0) {
79 switch (pReloc.type()) {
80 case llvm::ELF::R_ARM_THM_CALL: {
81 // FIXME: Assuming blx is available (i.e., target is armv5 or above!)
82 // then, we do not need a stub unless the branch target is too far.
83 uint64_t dest = pTargetSymValue + pReloc.addend() + 4u;
84 int64_t branch_offset = static_cast<int64_t>(dest) - pSource;
85 if (m_bUsingThumb2) {
86 if ((branch_offset > ARMGNULDBackend::THM2_MAX_FWD_BRANCH_OFFSET) ||
87 (branch_offset < ARMGNULDBackend::THM2_MAX_BWD_BRANCH_OFFSET)) {
88 result = true;
89 break;
90 }
91 } else {
92 if ((branch_offset > ARMGNULDBackend::THM_MAX_FWD_BRANCH_OFFSET) ||
93 (branch_offset < ARMGNULDBackend::THM_MAX_BWD_BRANCH_OFFSET)) {
94 result = true;
95 break;
96 }
97 }
98 break;
99 }
100 case llvm::ELF::R_ARM_THM_JUMP24: {
101 // always need a stub to switch mode
102 result = true;
103 break;
104 }
105 default:
106 break;
107 }
108 }
109 return result;
110 }
111
name() const112 const std::string& THMToARMStub::name() const
113 {
114 return m_Name;
115 }
116
getContent() const117 const uint8_t* THMToARMStub::getContent() const
118 {
119 return reinterpret_cast<const uint8_t*>(m_pData);
120 }
121
size() const122 size_t THMToARMStub::size() const
123 {
124 return m_Size;
125 }
126
alignment() const127 size_t THMToARMStub::alignment() const
128 {
129 return 4u;
130 }
131
132 // for T bit of this stub
initSymValue() const133 uint64_t THMToARMStub::initSymValue() const
134 {
135 return 0x1;
136 }
137
doClone()138 Stub* THMToARMStub::doClone()
139 {
140 return new THMToARMStub(m_pData,
141 m_Size,
142 fixup_begin(),
143 fixup_end(),
144 m_bUsingThumb2);
145 }
146