1 //===-- ARMELFObjectWriter.cpp - ARM ELF Writer ---------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 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 "MCTargetDesc/ARMMCTargetDesc.h" 11 #include "MCTargetDesc/ARMFixupKinds.h" 12 #include "llvm/ADT/Statistic.h" 13 #include "llvm/ADT/StringSwitch.h" 14 #include "llvm/MC/MCELFObjectWriter.h" 15 #include "llvm/MC/MCExpr.h" 16 #include "llvm/MC/MCSectionELF.h" 17 #include "llvm/MC/MCValue.h" 18 #include "llvm/Support/Debug.h" 19 #include "llvm/Support/ErrorHandling.h" 20 #include "llvm/Support/raw_ostream.h" 21 22 using namespace llvm; 23 24 namespace { 25 class ARMELFObjectWriter : public MCELFObjectTargetWriter { 26 enum { DefaultEABIVersion = 0x05000000U }; 27 unsigned GetRelocTypeInner(const MCValue &Target, 28 const MCFixup &Fixup, 29 bool IsPCRel) const; 30 31 32 public: 33 ARMELFObjectWriter(uint8_t OSABI); 34 35 ~ARMELFObjectWriter() override; 36 37 unsigned getRelocType(MCContext &Ctx, const MCValue &Target, 38 const MCFixup &Fixup, bool IsPCRel) const override; 39 40 bool needsRelocateWithSymbol(const MCSymbol &Sym, 41 unsigned Type) const override; 42 }; 43 } 44 45 ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI) 46 : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI, 47 ELF::EM_ARM, 48 /*HasRelocationAddend*/ false) {} 49 50 ARMELFObjectWriter::~ARMELFObjectWriter() {} 51 52 bool ARMELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym, 53 unsigned Type) const { 54 // FIXME: This is extremely conservative. This really needs to use a 55 // whitelist with a clear explanation for why each realocation needs to 56 // point to the symbol, not to the section. 57 switch (Type) { 58 default: 59 return true; 60 61 case ELF::R_ARM_PREL31: 62 case ELF::R_ARM_ABS32: 63 return false; 64 } 65 } 66 67 // Need to examine the Fixup when determining whether to 68 // emit the relocation as an explicit symbol or as a section relative 69 // offset 70 unsigned ARMELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target, 71 const MCFixup &Fixup, 72 bool IsPCRel) const { 73 return GetRelocTypeInner(Target, Fixup, IsPCRel); 74 } 75 76 unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target, 77 const MCFixup &Fixup, 78 bool IsPCRel) const { 79 MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant(); 80 81 unsigned Type = 0; 82 if (IsPCRel) { 83 switch ((unsigned)Fixup.getKind()) { 84 default: 85 report_fatal_error("unsupported relocation on symbol"); 86 return ELF::R_ARM_NONE; 87 case FK_Data_4: 88 switch (Modifier) { 89 default: llvm_unreachable("Unsupported Modifier"); 90 case MCSymbolRefExpr::VK_None: 91 Type = ELF::R_ARM_REL32; 92 break; 93 case MCSymbolRefExpr::VK_TLSGD: 94 llvm_unreachable("unimplemented"); 95 case MCSymbolRefExpr::VK_GOTTPOFF: 96 Type = ELF::R_ARM_TLS_IE32; 97 break; 98 case MCSymbolRefExpr::VK_ARM_GOT_PREL: 99 Type = ELF::R_ARM_GOT_PREL; 100 break; 101 case MCSymbolRefExpr::VK_ARM_PREL31: 102 Type = ELF::R_ARM_PREL31; 103 break; 104 } 105 break; 106 case ARM::fixup_arm_blx: 107 case ARM::fixup_arm_uncondbl: 108 switch (Modifier) { 109 case MCSymbolRefExpr::VK_PLT: 110 Type = ELF::R_ARM_CALL; 111 break; 112 case MCSymbolRefExpr::VK_TLSCALL: 113 Type = ELF::R_ARM_TLS_CALL; 114 break; 115 default: 116 Type = ELF::R_ARM_CALL; 117 break; 118 } 119 break; 120 case ARM::fixup_arm_condbl: 121 case ARM::fixup_arm_condbranch: 122 case ARM::fixup_arm_uncondbranch: 123 Type = ELF::R_ARM_JUMP24; 124 break; 125 case ARM::fixup_t2_condbranch: 126 Type = ELF::R_ARM_THM_JUMP19; 127 break; 128 case ARM::fixup_t2_uncondbranch: 129 Type = ELF::R_ARM_THM_JUMP24; 130 break; 131 case ARM::fixup_arm_movt_hi16: 132 Type = ELF::R_ARM_MOVT_PREL; 133 break; 134 case ARM::fixup_arm_movw_lo16: 135 Type = ELF::R_ARM_MOVW_PREL_NC; 136 break; 137 case ARM::fixup_t2_movt_hi16: 138 Type = ELF::R_ARM_THM_MOVT_PREL; 139 break; 140 case ARM::fixup_t2_movw_lo16: 141 Type = ELF::R_ARM_THM_MOVW_PREL_NC; 142 break; 143 case ARM::fixup_arm_thumb_bl: 144 case ARM::fixup_arm_thumb_blx: 145 switch (Modifier) { 146 case MCSymbolRefExpr::VK_TLSCALL: 147 Type = ELF::R_ARM_THM_TLS_CALL; 148 break; 149 default: 150 Type = ELF::R_ARM_THM_CALL; 151 break; 152 } 153 break; 154 } 155 } else { 156 switch ((unsigned)Fixup.getKind()) { 157 default: 158 report_fatal_error("unsupported relocation on symbol"); 159 return ELF::R_ARM_NONE; 160 case FK_Data_1: 161 switch (Modifier) { 162 default: llvm_unreachable("unsupported Modifier"); 163 case MCSymbolRefExpr::VK_None: 164 Type = ELF::R_ARM_ABS8; 165 break; 166 } 167 break; 168 case FK_Data_2: 169 switch (Modifier) { 170 default: llvm_unreachable("unsupported modifier"); 171 case MCSymbolRefExpr::VK_None: 172 Type = ELF::R_ARM_ABS16; 173 break; 174 } 175 break; 176 case FK_Data_4: 177 switch (Modifier) { 178 default: llvm_unreachable("Unsupported Modifier"); 179 case MCSymbolRefExpr::VK_ARM_NONE: 180 Type = ELF::R_ARM_NONE; 181 break; 182 case MCSymbolRefExpr::VK_GOT: 183 Type = ELF::R_ARM_GOT_BREL; 184 break; 185 case MCSymbolRefExpr::VK_TLSGD: 186 Type = ELF::R_ARM_TLS_GD32; 187 break; 188 case MCSymbolRefExpr::VK_TPOFF: 189 Type = ELF::R_ARM_TLS_LE32; 190 break; 191 case MCSymbolRefExpr::VK_GOTTPOFF: 192 Type = ELF::R_ARM_TLS_IE32; 193 break; 194 case MCSymbolRefExpr::VK_None: 195 Type = ELF::R_ARM_ABS32; 196 break; 197 case MCSymbolRefExpr::VK_GOTOFF: 198 Type = ELF::R_ARM_GOTOFF32; 199 break; 200 case MCSymbolRefExpr::VK_ARM_GOT_PREL: 201 Type = ELF::R_ARM_GOT_PREL; 202 break; 203 case MCSymbolRefExpr::VK_ARM_TARGET1: 204 Type = ELF::R_ARM_TARGET1; 205 break; 206 case MCSymbolRefExpr::VK_ARM_TARGET2: 207 Type = ELF::R_ARM_TARGET2; 208 break; 209 case MCSymbolRefExpr::VK_ARM_PREL31: 210 Type = ELF::R_ARM_PREL31; 211 break; 212 case MCSymbolRefExpr::VK_ARM_SBREL: 213 Type = ELF::R_ARM_SBREL32; 214 break; 215 case MCSymbolRefExpr::VK_ARM_TLSLDO: 216 Type = ELF::R_ARM_TLS_LDO32; 217 break; 218 case MCSymbolRefExpr::VK_TLSCALL: 219 Type = ELF::R_ARM_TLS_CALL; 220 break; 221 case MCSymbolRefExpr::VK_TLSDESC: 222 Type = ELF::R_ARM_TLS_GOTDESC; 223 break; 224 case MCSymbolRefExpr::VK_ARM_TLSDESCSEQ: 225 Type = ELF::R_ARM_TLS_DESCSEQ; 226 break; 227 } 228 break; 229 case ARM::fixup_arm_ldst_pcrel_12: 230 case ARM::fixup_arm_pcrel_10: 231 case ARM::fixup_arm_adr_pcrel_12: 232 case ARM::fixup_arm_thumb_bl: 233 case ARM::fixup_arm_thumb_cb: 234 case ARM::fixup_arm_thumb_cp: 235 case ARM::fixup_arm_thumb_br: 236 llvm_unreachable("Unimplemented"); 237 case ARM::fixup_arm_condbranch: 238 case ARM::fixup_arm_uncondbranch: 239 Type = ELF::R_ARM_JUMP24; 240 break; 241 case ARM::fixup_arm_movt_hi16: 242 Type = ELF::R_ARM_MOVT_ABS; 243 break; 244 case ARM::fixup_arm_movw_lo16: 245 Type = ELF::R_ARM_MOVW_ABS_NC; 246 break; 247 case ARM::fixup_t2_movt_hi16: 248 Type = ELF::R_ARM_THM_MOVT_ABS; 249 break; 250 case ARM::fixup_t2_movw_lo16: 251 Type = ELF::R_ARM_THM_MOVW_ABS_NC; 252 break; 253 } 254 } 255 256 return Type; 257 } 258 259 MCObjectWriter *llvm::createARMELFObjectWriter(raw_pwrite_stream &OS, 260 uint8_t OSABI, 261 bool IsLittleEndian) { 262 MCELFObjectTargetWriter *MOTW = new ARMELFObjectWriter(OSABI); 263 return createELFObjectWriter(MOTW, OS, IsLittleEndian); 264 } 265
