1 //===-- X86ELFObjectWriter.cpp - X86 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/X86FixupKinds.h"
11 #include "MCTargetDesc/X86MCTargetDesc.h"
12 #include "llvm/MC/MCELFObjectWriter.h"
13 #include "llvm/MC/MCExpr.h"
14 #include "llvm/MC/MCValue.h"
15 #include "llvm/Support/ELF.h"
16 #include "llvm/Support/ErrorHandling.h"
17
18 using namespace llvm;
19
20 namespace {
21 class X86ELFObjectWriter : public MCELFObjectTargetWriter {
22 public:
23 X86ELFObjectWriter(bool IsELF64, uint8_t OSABI, uint16_t EMachine);
24
25 virtual ~X86ELFObjectWriter();
26 protected:
27 virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
28 bool IsPCRel, bool IsRelocWithSymbol,
29 int64_t Addend) const;
30 };
31 }
32
X86ELFObjectWriter(bool IsELF64,uint8_t OSABI,uint16_t EMachine)33 X86ELFObjectWriter::X86ELFObjectWriter(bool IsELF64, uint8_t OSABI,
34 uint16_t EMachine)
35 : MCELFObjectTargetWriter(IsELF64, OSABI, EMachine,
36 // Only i386 uses Rel instead of RelA.
37 /*HasRelocationAddend*/ EMachine != ELF::EM_386) {}
38
~X86ELFObjectWriter()39 X86ELFObjectWriter::~X86ELFObjectWriter()
40 {}
41
GetRelocType(const MCValue & Target,const MCFixup & Fixup,bool IsPCRel,bool IsRelocWithSymbol,int64_t Addend) const42 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
43 const MCFixup &Fixup,
44 bool IsPCRel,
45 bool IsRelocWithSymbol,
46 int64_t Addend) const {
47 // determine the type of the relocation
48
49 MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
50 MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
51 unsigned Type;
52 if (getEMachine() == ELF::EM_X86_64) {
53 if (IsPCRel) {
54 switch ((unsigned)Fixup.getKind()) {
55 default: llvm_unreachable("invalid fixup kind!");
56
57 case FK_Data_8: Type = ELF::R_X86_64_PC64; break;
58 case FK_Data_4: Type = ELF::R_X86_64_PC32; break;
59 case FK_Data_2: Type = ELF::R_X86_64_PC16; break;
60
61 case FK_PCRel_8:
62 assert(Modifier == MCSymbolRefExpr::VK_None);
63 Type = ELF::R_X86_64_PC64;
64 break;
65 case X86::reloc_signed_4byte:
66 case X86::reloc_riprel_4byte_movq_load:
67 case X86::reloc_riprel_4byte:
68 case FK_PCRel_4:
69 switch (Modifier) {
70 default:
71 llvm_unreachable("Unimplemented");
72 case MCSymbolRefExpr::VK_None:
73 Type = ELF::R_X86_64_PC32;
74 break;
75 case MCSymbolRefExpr::VK_PLT:
76 Type = ELF::R_X86_64_PLT32;
77 break;
78 case MCSymbolRefExpr::VK_GOTPCREL:
79 Type = ELF::R_X86_64_GOTPCREL;
80 break;
81 case MCSymbolRefExpr::VK_GOTTPOFF:
82 Type = ELF::R_X86_64_GOTTPOFF;
83 break;
84 case MCSymbolRefExpr::VK_TLSGD:
85 Type = ELF::R_X86_64_TLSGD;
86 break;
87 case MCSymbolRefExpr::VK_TLSLD:
88 Type = ELF::R_X86_64_TLSLD;
89 break;
90 }
91 break;
92 case FK_PCRel_2:
93 assert(Modifier == MCSymbolRefExpr::VK_None);
94 Type = ELF::R_X86_64_PC16;
95 break;
96 case FK_PCRel_1:
97 assert(Modifier == MCSymbolRefExpr::VK_None);
98 Type = ELF::R_X86_64_PC8;
99 break;
100 }
101 } else {
102 switch ((unsigned)Fixup.getKind()) {
103 default: llvm_unreachable("invalid fixup kind!");
104 case FK_Data_8:
105 switch (Modifier) {
106 default:
107 llvm_unreachable("Unimplemented");
108 case MCSymbolRefExpr::VK_None:
109 Type = ELF::R_X86_64_64;
110 break;
111 case MCSymbolRefExpr::VK_DTPOFF:
112 Type = ELF::R_X86_64_DTPOFF64;
113 break;
114 }
115 break;
116 case X86::reloc_signed_4byte:
117 switch (Modifier) {
118 default:
119 llvm_unreachable("Unimplemented");
120 case MCSymbolRefExpr::VK_None:
121 Type = ELF::R_X86_64_32S;
122 break;
123 case MCSymbolRefExpr::VK_GOT:
124 Type = ELF::R_X86_64_GOT32;
125 break;
126 case MCSymbolRefExpr::VK_GOTPCREL:
127 Type = ELF::R_X86_64_GOTPCREL;
128 break;
129 case MCSymbolRefExpr::VK_TPOFF:
130 Type = ELF::R_X86_64_TPOFF32;
131 break;
132 case MCSymbolRefExpr::VK_DTPOFF:
133 Type = ELF::R_X86_64_DTPOFF32;
134 break;
135 }
136 break;
137 case FK_Data_4:
138 Type = ELF::R_X86_64_32;
139 break;
140 case FK_Data_2: Type = ELF::R_X86_64_16; break;
141 case FK_PCRel_1:
142 case FK_Data_1: Type = ELF::R_X86_64_8; break;
143 }
144 }
145 } else if (getEMachine() == ELF::EM_386) {
146 if (IsPCRel) {
147 switch ((unsigned)Fixup.getKind()) {
148 default: llvm_unreachable("invalid fixup kind!");
149
150 case X86::reloc_global_offset_table:
151 Type = ELF::R_386_GOTPC;
152 break;
153
154 case X86::reloc_signed_4byte:
155 case FK_PCRel_4:
156 case FK_Data_4:
157 switch (Modifier) {
158 default:
159 llvm_unreachable("Unimplemented");
160 case MCSymbolRefExpr::VK_None:
161 Type = ELF::R_386_PC32;
162 break;
163 case MCSymbolRefExpr::VK_PLT:
164 Type = ELF::R_386_PLT32;
165 break;
166 }
167 break;
168 }
169 } else {
170 switch ((unsigned)Fixup.getKind()) {
171 default: llvm_unreachable("invalid fixup kind!");
172
173 case X86::reloc_global_offset_table:
174 Type = ELF::R_386_GOTPC;
175 break;
176
177 // FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
178 // instead?
179 case X86::reloc_signed_4byte:
180 case FK_PCRel_4:
181 case FK_Data_4:
182 switch (Modifier) {
183 default:
184 llvm_unreachable("Unimplemented");
185 case MCSymbolRefExpr::VK_None:
186 Type = ELF::R_386_32;
187 break;
188 case MCSymbolRefExpr::VK_GOT:
189 Type = ELF::R_386_GOT32;
190 break;
191 case MCSymbolRefExpr::VK_GOTOFF:
192 Type = ELF::R_386_GOTOFF;
193 break;
194 case MCSymbolRefExpr::VK_TLSGD:
195 Type = ELF::R_386_TLS_GD;
196 break;
197 case MCSymbolRefExpr::VK_TPOFF:
198 Type = ELF::R_386_TLS_LE_32;
199 break;
200 case MCSymbolRefExpr::VK_INDNTPOFF:
201 Type = ELF::R_386_TLS_IE;
202 break;
203 case MCSymbolRefExpr::VK_NTPOFF:
204 Type = ELF::R_386_TLS_LE;
205 break;
206 case MCSymbolRefExpr::VK_GOTNTPOFF:
207 Type = ELF::R_386_TLS_GOTIE;
208 break;
209 case MCSymbolRefExpr::VK_TLSLDM:
210 Type = ELF::R_386_TLS_LDM;
211 break;
212 case MCSymbolRefExpr::VK_DTPOFF:
213 Type = ELF::R_386_TLS_LDO_32;
214 break;
215 case MCSymbolRefExpr::VK_GOTTPOFF:
216 Type = ELF::R_386_TLS_IE_32;
217 break;
218 }
219 break;
220 case FK_Data_2: Type = ELF::R_386_16; break;
221 case FK_PCRel_1:
222 case FK_Data_1: Type = ELF::R_386_8; break;
223 }
224 }
225 } else
226 llvm_unreachable("Unsupported ELF machine type.");
227
228 return Type;
229 }
230
createX86ELFObjectWriter(raw_ostream & OS,bool IsELF64,uint8_t OSABI,uint16_t EMachine)231 MCObjectWriter *llvm::createX86ELFObjectWriter(raw_ostream &OS,
232 bool IsELF64,
233 uint8_t OSABI,
234 uint16_t EMachine) {
235 MCELFObjectTargetWriter *MOTW =
236 new X86ELFObjectWriter(IsELF64, OSABI, EMachine);
237 return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);
238 }
239