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 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 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 68 THMToARMStub::~THMToARMStub() 69 { 70 } 71 72 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 } 111 112 const std::string& THMToARMStub::name() const 113 { 114 return m_Name; 115 } 116 117 const uint8_t* THMToARMStub::getContent() const 118 { 119 return reinterpret_cast<const uint8_t*>(m_pData); 120 } 121 122 size_t THMToARMStub::size() const 123 { 124 return m_Size; 125 } 126 127 size_t THMToARMStub::alignment() const 128 { 129 return 4u; 130 } 131 132 // for T bit of this stub 133 uint64_t THMToARMStub::initSymValue() const 134 { 135 return 0x1; 136 } 137 138 Stub* THMToARMStub::doClone() 139 { 140 return new THMToARMStub(m_pData, 141 m_Size, 142 fixup_begin(), 143 fixup_end(), 144 m_bUsingThumb2); 145 } 146
