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 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 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 67 THMToARMStub::~THMToARMStub() { 68 } 69 70 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 } 108 109 const std::string& THMToARMStub::name() const { 110 return m_Name; 111 } 112 113 const uint8_t* THMToARMStub::getContent() const { 114 return reinterpret_cast<const uint8_t*>(m_pData); 115 } 116 117 size_t THMToARMStub::size() const { 118 return m_Size; 119 } 120 121 size_t THMToARMStub::alignment() const { 122 return 4u; 123 } 124 125 // for T bit of this stub 126 uint64_t THMToARMStub::initSymValue() const { 127 return 0x1; 128 } 129 130 Stub* THMToARMStub::doClone() { 131 return new THMToARMStub( 132 m_pData, m_Size, fixup_begin(), fixup_end(), m_bUsingThumb2); 133 } 134 135 } // namespace mcld 136
