1 //===-- ARMELFObjectWriter.cpp - ARM ELF Writer ---------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "MCTargetDesc/ARMFixupKinds.h"
11 #include "MCTargetDesc/ARMMCTargetDesc.h"
12 #include "llvm/BinaryFormat/ELF.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCELFObjectWriter.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCFixup.h"
17 #include "llvm/MC/MCObjectFileInfo.h"
18 #include "llvm/MC/MCObjectWriter.h"
19 #include "llvm/MC/MCValue.h"
20 #include "llvm/Support/ErrorHandling.h"
21 #include "llvm/Support/raw_ostream.h"
28 class ARMELFObjectWriter : public MCELFObjectTargetWriter {
29 enum { DefaultEABIVersion = 0x05000000U };
31 unsigned GetRelocTypeInner(const MCValue &Target, const MCFixup &Fixup,
32 bool IsPCRel, MCContext &Ctx) const;
35 ARMELFObjectWriter(uint8_t OSABI);
37 ~ARMELFObjectWriter() override = default;
39 unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
40 const MCFixup &Fixup, bool IsPCRel) const override;
42 bool needsRelocateWithSymbol(const MCSymbol &Sym,
43 unsigned Type) const override;
45 void addTargetSectionFlags(MCContext &Ctx, MCSectionELF &Sec) override;
48 } // end anonymous namespace
50 ARMELFObjectWriter::ARMELFObjectWriter(uint8_t OSABI)
51 : MCELFObjectTargetWriter(/*Is64Bit*/ false, OSABI,
53 /*HasRelocationAddend*/ false) {}
55 bool ARMELFObjectWriter::needsRelocateWithSymbol(const MCSymbol &Sym,
56 unsigned Type) const {
57 // FIXME: This is extremely conservative. This really needs to use a
58 // whitelist with a clear explanation for why each realocation needs to
59 // point to the symbol, not to the section.
64 case ELF::R_ARM_PREL31:
65 case ELF::R_ARM_ABS32:
70 // Need to examine the Fixup when determining whether to
71 // emit the relocation as an explicit symbol or as a section relative
73 unsigned ARMELFObjectWriter::getRelocType(MCContext &Ctx, const MCValue &Target,
76 return GetRelocTypeInner(Target, Fixup, IsPCRel, Ctx);
79 unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
82 MCContext &Ctx) const {
83 MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
86 switch ((unsigned)Fixup.getKind()) {
88 Ctx.reportFatalError(Fixup.getLoc(), "unsupported relocation on symbol");
89 return ELF::R_ARM_NONE;
93 llvm_unreachable("Unsupported Modifier");
94 case MCSymbolRefExpr::VK_None:
95 return ELF::R_ARM_REL32;
96 case MCSymbolRefExpr::VK_GOTTPOFF:
97 return ELF::R_ARM_TLS_IE32;
98 case MCSymbolRefExpr::VK_ARM_GOT_PREL:
99 return ELF::R_ARM_GOT_PREL;
100 case MCSymbolRefExpr::VK_ARM_PREL31:
101 return ELF::R_ARM_PREL31;
103 case ARM::fixup_arm_blx:
104 case ARM::fixup_arm_uncondbl:
106 case MCSymbolRefExpr::VK_PLT:
107 return ELF::R_ARM_CALL;
108 case MCSymbolRefExpr::VK_TLSCALL:
109 return ELF::R_ARM_TLS_CALL;
111 return ELF::R_ARM_CALL;
113 case ARM::fixup_arm_condbl:
114 case ARM::fixup_arm_condbranch:
115 case ARM::fixup_arm_uncondbranch:
116 return ELF::R_ARM_JUMP24;
117 case ARM::fixup_t2_condbranch:
118 return ELF::R_ARM_THM_JUMP19;
119 case ARM::fixup_t2_uncondbranch:
120 return ELF::R_ARM_THM_JUMP24;
121 case ARM::fixup_arm_movt_hi16:
122 return ELF::R_ARM_MOVT_PREL;
123 case ARM::fixup_arm_movw_lo16:
124 return ELF::R_ARM_MOVW_PREL_NC;
125 case ARM::fixup_t2_movt_hi16:
126 return ELF::R_ARM_THM_MOVT_PREL;
127 case ARM::fixup_t2_movw_lo16:
128 return ELF::R_ARM_THM_MOVW_PREL_NC;
129 case ARM::fixup_arm_thumb_br:
130 return ELF::R_ARM_THM_JUMP11;
131 case ARM::fixup_arm_thumb_bcc:
132 return ELF::R_ARM_THM_JUMP8;
133 case ARM::fixup_arm_thumb_bl:
134 case ARM::fixup_arm_thumb_blx:
136 case MCSymbolRefExpr::VK_TLSCALL:
137 return ELF::R_ARM_THM_TLS_CALL;
139 return ELF::R_ARM_THM_CALL;
143 switch ((unsigned)Fixup.getKind()) {
145 Ctx.reportFatalError(Fixup.getLoc(), "unsupported relocation on symbol");
146 return ELF::R_ARM_NONE;
150 llvm_unreachable("unsupported Modifier");
151 case MCSymbolRefExpr::VK_None:
152 return ELF::R_ARM_ABS8;
157 llvm_unreachable("unsupported modifier");
158 case MCSymbolRefExpr::VK_None:
159 return ELF::R_ARM_ABS16;
164 llvm_unreachable("Unsupported Modifier");
165 case MCSymbolRefExpr::VK_ARM_NONE:
166 return ELF::R_ARM_NONE;
167 case MCSymbolRefExpr::VK_GOT:
168 return ELF::R_ARM_GOT_BREL;
169 case MCSymbolRefExpr::VK_TLSGD:
170 return ELF::R_ARM_TLS_GD32;
171 case MCSymbolRefExpr::VK_TPOFF:
172 return ELF::R_ARM_TLS_LE32;
173 case MCSymbolRefExpr::VK_GOTTPOFF:
174 return ELF::R_ARM_TLS_IE32;
175 case MCSymbolRefExpr::VK_None:
176 return ELF::R_ARM_ABS32;
177 case MCSymbolRefExpr::VK_GOTOFF:
178 return ELF::R_ARM_GOTOFF32;
179 case MCSymbolRefExpr::VK_ARM_GOT_PREL:
180 return ELF::R_ARM_GOT_PREL;
181 case MCSymbolRefExpr::VK_ARM_TARGET1:
182 return ELF::R_ARM_TARGET1;
183 case MCSymbolRefExpr::VK_ARM_TARGET2:
184 return ELF::R_ARM_TARGET2;
185 case MCSymbolRefExpr::VK_ARM_PREL31:
186 return ELF::R_ARM_PREL31;
187 case MCSymbolRefExpr::VK_ARM_SBREL:
188 return ELF::R_ARM_SBREL32;
189 case MCSymbolRefExpr::VK_ARM_TLSLDO:
190 return ELF::R_ARM_TLS_LDO32;
191 case MCSymbolRefExpr::VK_TLSCALL:
192 return ELF::R_ARM_TLS_CALL;
193 case MCSymbolRefExpr::VK_TLSDESC:
194 return ELF::R_ARM_TLS_GOTDESC;
195 case MCSymbolRefExpr::VK_TLSLDM:
196 return ELF::R_ARM_TLS_LDM32;
197 case MCSymbolRefExpr::VK_ARM_TLSDESCSEQ:
198 return ELF::R_ARM_TLS_DESCSEQ;
200 case ARM::fixup_arm_condbranch:
201 case ARM::fixup_arm_uncondbranch:
202 return ELF::R_ARM_JUMP24;
203 case ARM::fixup_arm_movt_hi16:
206 llvm_unreachable("Unsupported Modifier");
207 case MCSymbolRefExpr::VK_None:
208 return ELF::R_ARM_MOVT_ABS;
209 case MCSymbolRefExpr::VK_ARM_SBREL:
210 return ELF::R_ARM_MOVT_BREL;
212 case ARM::fixup_arm_movw_lo16:
215 llvm_unreachable("Unsupported Modifier");
216 case MCSymbolRefExpr::VK_None:
217 return ELF::R_ARM_MOVW_ABS_NC;
218 case MCSymbolRefExpr::VK_ARM_SBREL:
219 return ELF::R_ARM_MOVW_BREL_NC;
221 case ARM::fixup_t2_movt_hi16:
224 llvm_unreachable("Unsupported Modifier");
225 case MCSymbolRefExpr::VK_None:
226 return ELF::R_ARM_THM_MOVT_ABS;
227 case MCSymbolRefExpr::VK_ARM_SBREL:
228 return ELF::R_ARM_THM_MOVT_BREL;
230 case ARM::fixup_t2_movw_lo16:
233 llvm_unreachable("Unsupported Modifier");
234 case MCSymbolRefExpr::VK_None:
235 return ELF::R_ARM_THM_MOVW_ABS_NC;
236 case MCSymbolRefExpr::VK_ARM_SBREL:
237 return ELF::R_ARM_THM_MOVW_BREL_NC;
242 void ARMELFObjectWriter::addTargetSectionFlags(MCContext &Ctx,
244 // The mix of execute-only and non-execute-only at link time is
245 // non-execute-only. To avoid the empty implicitly created .text
246 // section from making the whole .text section non-execute-only, we
247 // mark it execute-only if it is empty and there is at least one
248 // execute-only section in the object.
249 MCSectionELF *TextSection =
250 static_cast<MCSectionELF *>(Ctx.getObjectFileInfo()->getTextSection());
251 if (Sec.getKind().isExecuteOnly() && !TextSection->hasInstructions() &&
252 !TextSection->hasData()) {
253 TextSection->setFlags(TextSection->getFlags() | ELF::SHF_ARM_PURECODE);
257 std::unique_ptr<MCObjectTargetWriter>
258 llvm::createARMELFObjectWriter(uint8_t OSABI) {
259 return llvm::make_unique<ARMELFObjectWriter>(OSABI);