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 ~X86ELFObjectWriter() override;
26
27 protected:
28 unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
29 bool IsPCRel) const override;
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
42 enum X86_64RelType { RT64_64, RT64_32, RT64_32S, RT64_16, RT64_8 };
43
getType64(unsigned Kind,MCSymbolRefExpr::VariantKind & Modifier,bool & IsPCRel)44 static X86_64RelType getType64(unsigned Kind,
45 MCSymbolRefExpr::VariantKind &Modifier,
46 bool &IsPCRel) {
47 switch (Kind) {
48 default:
49 llvm_unreachable("Unimplemented");
50 case X86::reloc_global_offset_table8:
51 Modifier = MCSymbolRefExpr::VK_GOT;
52 IsPCRel = true;
53 return RT64_64;
54 case FK_Data_8:
55 return RT64_64;
56 case X86::reloc_signed_4byte:
57 if (Modifier == MCSymbolRefExpr::VK_None && !IsPCRel)
58 return RT64_32S;
59 return RT64_32;
60 case X86::reloc_global_offset_table:
61 Modifier = MCSymbolRefExpr::VK_GOT;
62 IsPCRel = true;
63 return RT64_32;
64 case FK_Data_4:
65 case FK_PCRel_4:
66 case X86::reloc_riprel_4byte:
67 case X86::reloc_riprel_4byte_movq_load:
68 return RT64_32;
69 case FK_PCRel_2:
70 case FK_Data_2:
71 return RT64_16;
72 case FK_PCRel_1:
73 case FK_Data_1:
74 return RT64_8;
75 }
76 }
77
getRelocType64(MCSymbolRefExpr::VariantKind Modifier,X86_64RelType Type,bool IsPCRel)78 static unsigned getRelocType64(MCSymbolRefExpr::VariantKind Modifier,
79 X86_64RelType Type, bool IsPCRel) {
80 switch (Modifier) {
81 default:
82 llvm_unreachable("Unimplemented");
83 case MCSymbolRefExpr::VK_None:
84 switch (Type) {
85 case RT64_64:
86 return IsPCRel ? ELF::R_X86_64_PC64 : ELF::R_X86_64_64;
87 case RT64_32:
88 return IsPCRel ? ELF::R_X86_64_PC32 : ELF::R_X86_64_32;
89 case RT64_32S:
90 return ELF::R_X86_64_32S;
91 case RT64_16:
92 return IsPCRel ? ELF::R_X86_64_PC16 : ELF::R_X86_64_16;
93 case RT64_8:
94 return IsPCRel ? ELF::R_X86_64_PC8 : ELF::R_X86_64_8;
95 }
96 case MCSymbolRefExpr::VK_GOT:
97 switch (Type) {
98 case RT64_64:
99 return IsPCRel ? ELF::R_X86_64_GOTPC64 : ELF::R_X86_64_GOT64;
100 case RT64_32:
101 return IsPCRel ? ELF::R_X86_64_GOTPC32 : ELF::R_X86_64_GOT32;
102 case RT64_32S:
103 case RT64_16:
104 case RT64_8:
105 llvm_unreachable("Unimplemented");
106 }
107 case MCSymbolRefExpr::VK_GOTOFF:
108 assert(Type == RT64_64);
109 assert(!IsPCRel);
110 return ELF::R_X86_64_GOTOFF64;
111 case MCSymbolRefExpr::VK_TPOFF:
112 assert(!IsPCRel);
113 switch (Type) {
114 case RT64_64:
115 return ELF::R_X86_64_TPOFF64;
116 case RT64_32:
117 return ELF::R_X86_64_TPOFF32;
118 case RT64_32S:
119 case RT64_16:
120 case RT64_8:
121 llvm_unreachable("Unimplemented");
122 }
123 case MCSymbolRefExpr::VK_DTPOFF:
124 assert(!IsPCRel);
125 switch (Type) {
126 case RT64_64:
127 return ELF::R_X86_64_DTPOFF64;
128 case RT64_32:
129 return ELF::R_X86_64_DTPOFF32;
130 case RT64_32S:
131 case RT64_16:
132 case RT64_8:
133 llvm_unreachable("Unimplemented");
134 }
135 case MCSymbolRefExpr::VK_SIZE:
136 assert(!IsPCRel);
137 switch (Type) {
138 case RT64_64:
139 return ELF::R_X86_64_SIZE64;
140 case RT64_32:
141 return ELF::R_X86_64_SIZE32;
142 case RT64_32S:
143 case RT64_16:
144 case RT64_8:
145 llvm_unreachable("Unimplemented");
146 }
147 case MCSymbolRefExpr::VK_TLSGD:
148 assert(Type == RT64_32);
149 return ELF::R_X86_64_TLSGD;
150 case MCSymbolRefExpr::VK_GOTTPOFF:
151 assert(Type == RT64_32);
152 return ELF::R_X86_64_GOTTPOFF;
153 case MCSymbolRefExpr::VK_TLSLD:
154 assert(Type == RT64_32);
155 return ELF::R_X86_64_TLSLD;
156 case MCSymbolRefExpr::VK_PLT:
157 assert(Type == RT64_32);
158 return ELF::R_X86_64_PLT32;
159 case MCSymbolRefExpr::VK_GOTPCREL:
160 assert(Type == RT64_32);
161 return ELF::R_X86_64_GOTPCREL;
162 }
163 }
164
165 enum X86_32RelType { RT32_32, RT32_16, RT32_8 };
166
getType32(X86_64RelType T)167 static X86_32RelType getType32(X86_64RelType T) {
168 switch (T) {
169 case RT64_64:
170 llvm_unreachable("Unimplemented");
171 case RT64_32:
172 case RT64_32S:
173 return RT32_32;
174 case RT64_16:
175 return RT32_16;
176 case RT64_8:
177 return RT32_8;
178 }
179 llvm_unreachable("unexpected relocation type!");
180 }
181
getRelocType32(MCSymbolRefExpr::VariantKind Modifier,X86_32RelType Type,bool IsPCRel)182 static unsigned getRelocType32(MCSymbolRefExpr::VariantKind Modifier,
183 X86_32RelType Type, bool IsPCRel) {
184 switch (Modifier) {
185 default:
186 llvm_unreachable("Unimplemented");
187 case MCSymbolRefExpr::VK_None:
188 switch (Type) {
189 case RT32_32:
190 return IsPCRel ? ELF::R_386_PC32 : ELF::R_386_32;
191 case RT32_16:
192 return IsPCRel ? ELF::R_386_PC16 : ELF::R_386_16;
193 case RT32_8:
194 return IsPCRel ? ELF::R_386_PC8 : ELF::R_386_8;
195 }
196 case MCSymbolRefExpr::VK_GOT:
197 assert(Type == RT32_32);
198 return IsPCRel ? ELF::R_386_GOTPC : ELF::R_386_GOT32;
199 case MCSymbolRefExpr::VK_GOTOFF:
200 assert(Type == RT32_32);
201 assert(!IsPCRel);
202 return ELF::R_386_GOTOFF;
203 case MCSymbolRefExpr::VK_TPOFF:
204 assert(Type == RT32_32);
205 assert(!IsPCRel);
206 return ELF::R_386_TLS_LE_32;
207 case MCSymbolRefExpr::VK_DTPOFF:
208 assert(Type == RT32_32);
209 assert(!IsPCRel);
210 return ELF::R_386_TLS_LDO_32;
211 case MCSymbolRefExpr::VK_TLSGD:
212 assert(Type == RT32_32);
213 assert(!IsPCRel);
214 return ELF::R_386_TLS_GD;
215 case MCSymbolRefExpr::VK_GOTTPOFF:
216 assert(Type == RT32_32);
217 assert(!IsPCRel);
218 return ELF::R_386_TLS_IE_32;
219 case MCSymbolRefExpr::VK_PLT:
220 assert(Type == RT32_32);
221 return ELF::R_386_PLT32;
222 case MCSymbolRefExpr::VK_INDNTPOFF:
223 assert(Type == RT32_32);
224 assert(!IsPCRel);
225 return ELF::R_386_TLS_IE;
226 case MCSymbolRefExpr::VK_NTPOFF:
227 assert(Type == RT32_32);
228 assert(!IsPCRel);
229 return ELF::R_386_TLS_LE;
230 case MCSymbolRefExpr::VK_GOTNTPOFF:
231 assert(Type == RT32_32);
232 assert(!IsPCRel);
233 return ELF::R_386_TLS_GOTIE;
234 case MCSymbolRefExpr::VK_TLSLDM:
235 assert(Type == RT32_32);
236 assert(!IsPCRel);
237 return ELF::R_386_TLS_LDM;
238 }
239 }
240
GetRelocType(const MCValue & Target,const MCFixup & Fixup,bool IsPCRel) const241 unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
242 const MCFixup &Fixup,
243 bool IsPCRel) const {
244 MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
245 X86_64RelType Type = getType64(Fixup.getKind(), Modifier, IsPCRel);
246 if (getEMachine() == ELF::EM_X86_64)
247 return getRelocType64(Modifier, Type, IsPCRel);
248
249 assert(getEMachine() == ELF::EM_386 && "Unsupported ELF machine type.");
250 return getRelocType32(Modifier, getType32(Type), IsPCRel);
251 }
252
createX86ELFObjectWriter(raw_pwrite_stream & OS,bool IsELF64,uint8_t OSABI,uint16_t EMachine)253 MCObjectWriter *llvm::createX86ELFObjectWriter(raw_pwrite_stream &OS,
254 bool IsELF64, uint8_t OSABI,
255 uint16_t EMachine) {
256 MCELFObjectTargetWriter *MOTW =
257 new X86ELFObjectWriter(IsELF64, OSABI, EMachine);
258 return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);
259 }
260